Experimental demonstration of NO reduction and ammonia slip  for diesel engine SCR system

Abstract

This paper aims to investigate the characteristics of selective catalytic reduction(SCR) in a V2O5-WO3/TiO2 catalyst by studying the key parameter, and obtain the control method of NH3 injection under sample test bench. Four parameters are defined and adopted to represent the NO-NH3 reaction characteristics. The effect of NH3/NO ratio(NSR), catalyst temperature and NH3 injection period on NO conversion efficiency and NH3 slip was investigated. The correlation between NH3 slip and ammonia saturation storage level was studied. The experimental results show that the ammonia saturation storage level has great effects on NO reduction and NH3 slip. The NO conversion efficiency and NH3 slip strongly depends on the ammonia saturation storage level. Under such condition, the NO conversion efficiency is best when the ammonia saturation storage level is 68.2%~73%, until the value reach to 75% before the NH3 slip. Pulse injection can improve the NO conversion efficiency and NH3 slip. The period of pulse injection has few influence on the mean value of NO at the outlet, however, it affects the peak value of NO and NH3 slip. Using varied period pulse injection can further improve NO conversion efficiency and restrain NH3 slip. The outlet NO is able to be reduced by adopting suitable NH3 pulse injection interval.