Abstract Three-staged combustion was experimented by Steinmuller (Germany)on a 15MW test boiler to reduce NO x formation.The reduction of NO x was reached mainly by changing coefficient of excess air
proportion between main fule and reducing fuel
velocity of staged air
feeding velocity of reducing fuel
length of reducing zone and pulverized coal fineness
etc.The results of this experiment were then applied to a 500MW boiler with a NO x emission within 400mg/m 3.