Patent ID: 7374736

Claim:
A method of decreasing the concentration of nitrogen oxides in a combustion flue gas comprising: a. forming a combustion flue gas in a combustion zone, the combustion flue gas comprising nitrogen oxides; b. introducing overfire air and the droplets of a solution or particles of a selective reducing agent in a burnout zone; c. mixing the overfire air and the selective reducing agent with the combustion flue gas in the burnout zone at a flue gas temperature above an optimal temperature range for reduction of the nitrogen oxides using the reducing agent, wherein the optional temperature range is above 1600° F.; d. heating with the combustion flue gas, the overfire air and the droplets or particles of the selective reducing agent to the optimal temperature range; e. reducing the nitrogen oxides with the selective reducing agent heated to the optimal temperature range, and f. continuing to increase the temperature of the overfire air and the selective reducing agent beyond the optimal temperature range with the flue gas.