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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.

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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:

1 Control of NO x

2 Two distinct reduction methods 1.Control over the reaction that produces the pollutant. (3T) 2.Removal of the pollutant after its formation

3 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

4 Effect of Excess Air

5 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 C to C pre-heat (as 3-fold)

6 Effect of Combustion-Zone Cooling

7 Effect of Furnace-Burner Configuration

8 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.

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10 Two-Stage of Off-Stochiometric Combustion Fuel and air are burnt near stochiometric conditions. First fuel-rich feed Second fuel-lean feed

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13 Status of Combustion Modification Techniques

14 Flue-Gas Control Methods for NOx Selective Catalitic Reduction Optimum reduction occurred 300 to C Platinum (Pt) or Palladium (Pd) optimum operation temperature C VnO 5 or TiO 2 optimum operation temperature C 75 to 90 % removal efficiency is possible

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16 Selective Non-Catalitic Reduction Urea or ammonia based chemical are injected 900 to C is needed for reaction Catalyst is eliminated 20 to 60 % reduction is possible

17 Example : 50 ppm NO is going to be reduced to 10 ppm. Determine the NH 3 amount needed for a plant having flowrate of 10 Nm 3 /sec


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