Presentation on theme: "Control of NO x. Two distinct reduction methods 1.Control over the reaction that produces the pollutant. (3T) 2.Removal of the pollutant after its formation."— Presentation transcript:
Two distinct reduction methods 1.Control over the reaction that produces the pollutant. (3T) 2.Removal of the pollutant after its formation
Combustion control methods for NO x from Stationary Sources 1.Effect of excess air 2.Effect of combustion air temperature 3.Effect of combustion-zone cooling 4.Effect of furnace-burner configuration 5.Flue gas recirculation 6.Two-stage or Off-stochiometric combustion 7.Status of combustion modification techniques
Effect of Combustion Air Temperature Waste heat is avaliable to help preheat air entering a combustion process. The added gas increases the flame temperature. Thus, NOx emissions increase. Significant formation occurs from 200 0 C to 300 0 C pre-heat (as 3-fold)
Flue-Gas Recirculation A portion of cooled flue gas is injected back into the combustion zone. Overall combustion temperature is reduced. Additionally O 2 amount is reduced. Gives the operator an additional element of control In amounts of up to 25 %, the recirculated gas negligible effect on flame development.
Flue-Gas Control Methods for NOx Selective Catalitic Reduction Optimum reduction occurred 300 to 400 0 C Platinum (Pt) or Palladium (Pd) optimum operation temperature 175-290 0 C VnO 5 or TiO 2 optimum operation temperature 260-450 0 C 75 to 90 % removal efficiency is possible