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Control of NO x

Control of NO x. Two distinct reduction methods Control over the reaction that produces the pollutant . (3T) Removal of the pollutant after its formation. Combustion control methods for NO x from Stationary Sources. Effect of excess air Effect of combustion air temperature

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Control of NO x

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  1. Control of NOx

  2. Twodistinctreductionmethods • Controloverthereactionthatproducesthepollutant. (3T) • Removal of thepollutantafteritsformation

  3. CombustioncontrolmethodsforNOxfromStationarySources • Effect of excessair • Effect of combustionairtemperature • Effect of combustion-zonecooling • Effect of furnace-burnerconfiguration • Fluegasrecirculation • Two-stageorOff-stochiometriccombustion • Status of combustionmodificationtechniques

  4. Effect of ExcessAir

  5. Effect of CombustionAirTemperature • Wasteheat is avaliabletohelppreheatairentering a combustionprocess. Theaddedgasincreasestheflametemperature. Thus, NOxemissionsincrease. • Significantformationoccursfrom 200 0C to 300 0C pre-heat (as 3-fold)

  6. Effect of Combustion-ZoneCooling

  7. Effect of Furnace-BurnerConfiguration

  8. Flue-GasRecirculation • A portion of cooledfluegas is injectedbackintothecombustionzone. • Overallcombustiontemperature is reduced. • Additionally O2amount is reduced. • Givestheoperator an additional element of control • Inamounts of upto 25 %, therecirculatedgasnegligibleeffect on flamedevelopment.

  9. Two-Stage of Off-StochiometricCombustion • Fuelandairareburntnearstochiometricconditions. • Firstfuel-richfeed • Secondfuel-leanfeed

  10. Status of CombustionModificationTechniques

  11. Flue-GasControlMethodsforNOx SelectiveCataliticReduction • Optimum reductionoccurred 300 to 400 0C • Platinum (Pt) orPalladium (Pd) optimum operationtemperature 175-290 0C • VnO5or TiO2 optimum operationtemperature 260-450 0C • 75 to 90 % removalefficiency is possible

  12. Ureaorammoniabasedchemicalareinjected • 900 to 1100 0C is neededforreaction • Catalyst is eliminated • 20 to 60 % reduction is possible • SelectiveNon-CataliticReduction

  13. Example : 50 ppm NO is goingto be reducedto 10 ppm. Determinethe NH3amountneededfor a planthavingflowrate of 10 Nm3/sec

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