Formation and reduction of NO from the oxidation of NH3/CH4 with high concentration of H2O.

Abstract This study investigated the homogeneous formation and reduction of NO from the oxidation of CH 4 /NH 3 to understand the effect of the high concentrations of H 2 O on NO emissions. The experimental results about the effects of excess oxygen ratio, gas compositions including H 2 O, CO 2 , NH 3 and recycled NO, on NO formation and reduction were presented. The mechanism about the effects of high concentration of H 2 O and combined effect of H 2 O/CO 2 on NO formation and reduction has been discussed. The results indicates that NO formation was markedly enhanced at high concentrations of H 2 O, which were mainly attributed to the increased OH radicals with steam addition at oxygen-rich conditions. By contrast, the radicals were consumed by reduction radicals, such as CO, H, and CH i radicals, under oxygen-lean conditions. NO concentrations followed the sequence of H 2 O/Ar > H 2 O/CO 2 > CO 2 /Ar under both the oxygen-rich and oxygen-lean conditions, which meant that the highest and lowest NO emissions were recorded in Ar/H 2 O and CO 2 /Ar respectively. The combined H 2 O/CO 2 concentration accordingly exerted an effective impact on NO reduction. The results about the effect of NH 3 concentration in fuel on NO emission showed that NO emission increased with increasing NH 3 concentration. Furthermore, NO reburning results implied that with increasing NO concentration, the total NO reduction increased, whereas the reduction ratio decreased. [ABSTRACT FROM AUTHOR]