Investigation on effects of water vapor on selective non-catalytic reduction of NOx

Experimental study on the influences of water vapor content on selective non-catalytic reduction (SNCR) using ammonia gas was carried out in a quartz tube reactor. The experimental results show that when the water vapor content increases: the optimum NOx reduction temperature and the NOx reduction temperature window both shift towards a higher temperature, the width of NOx reduction temperature window is widened and the optimal NOx reduction efficiency increases. The slip curves of NH3 shift little to a higher temperature and the emission curves of N2O would be somewhat higher. While there is the same water vapor content: Within temperature region lower than 900°C, the promotive effect of water vapor on NOx reduction is more notable as the ratio of NH3 to NOx is smaller. When temperature is about 1100°C, the promotive effect of water vapor on NOx reduction is more effective as the ratio of NH3 to NOx is larger. The promotive effect of water vapor on NOx reduction is more evident as the oxygen content is larger around temperature region which is between 1 000°C and 1100°C. © 2010 Chin.Soc.for Elec.Eng.