Experimental Study Of Volatile-N Conversion At O-2/Co2 Atmosphere In A Drop Tube Furnace

In coal combustion, NOx is largely formed from the oxidation of volatile nitrogen compounds such as HCN and NH3. The experiments on the volatile-N conversion to NO at O-2/CO2 atmosphere were carried out in a drop tube furnace. The effects of the excess oxygen ratio lambda (0.6-1.4), temperature (1000-1300 degrees C), O-2/CO2 ratio, and as well as CH4/NH3 mole ratio were investigated. To further understand the importance of NO reburn during volatile combustion, experiments were also performed with different concentrations of background NO (0-950 ppm). The results show that volatile-N conversion to NO is sensitive to excess oxygen ratio lambda at strongly oxidizing atmosphere. For volatile combustion, there is an optimal temperature and inlet O-2 concentration to minimize the volatile-N conversion to NO. The CH4/NH3 mole ratio plays an important role on the NO formation under oxidizing atmosphere. High levels of background NO prohibit the volatile-N conversion to NO significantly as the volatile-N conversion ratio decreases by 19-36%. The reburn fractions of recycle NO in fuel-rich and fuel-lean condition are 14.8% and 9.8% at 1200 degrees C, respectively.