Patent ID: 7261046

Claim:
A method of reducing nitrous oxide output and reducing pulverizer flammability in a coal-fired steam boiler system, the method comprising: receiving a primary air; heating a portion of the primary air to yield a heated air having a selected temperature; burning a first fuel mixture to produce a flue gas; cooling the flue gas; cleaning the flue gas utilizing a flue gas filter configured to remove particles from the flue gas to yield a cooled cleaned flue gas; recirculating a portion of the cooled cleaned flue gas from the output of the flue gas filter; admixing a selected amount of (i) the primary air, (ii) the heated air of the selected temperature, with (iii) the recirculated cooled cleaned flue gas, to form a control mixture with a controlled temperature according to a set of predetermined requirements; injecting the control mixture into a pulverizer, wherein the contents of the pulverizer include the first fuel air mixture; mixing the control mixture with the contents of the pulverizer, to produce a second fuel mixture; and burning the second fuel mixture in the boiler, wherein the second fuel mixture is less flammable than the first fuel mixture, and further wherein when the second fuel mixture is burned in the boiler, a reduced nitrous oxide output is achieved.