Effect of H2O Vapor on NO reduction by CO: experimental and kinetic modeling study

Abstract

The experiment and kinetic modeling prediction were conducted to investigate the effect of H2O vapor on NO reduction by CO. The experiment was performed in a 36-kW combustion reactor, and modeling prediction was done using the plug-flow reactor model. In the presence of H2O, the formation of free-radical H is conducive to NO reduction. H2O has a complex effect on NO emission: at T < 1100 degrees C, NO emission decreases with the increase of H2O content and temperature, the reaction pathway of NO reduction is NO -> HNO -> NH -> N2O -> N-2, and the controlling factors of NO reduction are temperature and H2O concentration;at 1100 degrees C < T < 1400 degrees C, NO emission decreases as the H2O content increases and remains constant with the change of temperature at [H2O] < 1.0%, NO reduction depends on H2O concentration rather than temperature, and increasing H2O concentration makes free-radical H reach high equilibrium concentration; at T > 1400 degrees C, the effects of H2O content and temperature on NO emission at [H2O] < 1.0% are similar to that at T < 1100 degrees C, NO emission increases with H2O content but decreases with temperature at [H2O] >1%, NO reduction depends on the combined effects of H and CO