Integrated process and apparatus for control of pollutants in coal-fired boilers

摘要

A method and apparatus for reducing SOx and NOx levels in flue gases generated by the combustion of coal in a boiler in which low NOx burners and air staging ports are utilized to inhibit the amount of NOx initially produced in the combustion of the coal, a selected concentration of urea is introduced downstream of the combustion zone after the temperature has been reduced to the range of 1300 DEG F. to 2000 DEG F., and a sodium-based reagent is introduced into the flue gas stream after further reducing the temperature of the stream to the range of 200 DEG F. to 900 DEG F. Under certain conditions, calcium injection may be employed along with humidification of the flue gas stream for selective reduction of the pollutants.