METHODS AND SYSTEMS FOR OPERATING COMBUSTION SYSTEMS

摘要

Methods and systems for reducing nitrogen oxides in combustion flue gas is provided. The method includes combusting a fuel (22) in a main combustion zone (14) such that a flow of combustion flue gas is generated wherein the combustion flue gas includes at least one nitrogen oxide species, establishing a fuel-rich zone, forming a plurality of reduced N-containing species in the fuel rich zone, injecting over-fire air into the combustion flue gas downstream of fuel rich zone, and controlling process parameters to provide conditions for the reduced N- containing species to react with the nitrogen oxides in the OFA zone to produce elemental nitrogen such that a concentration of nitrogen oxides is reduced.