循环流化床富氧燃烧NO和N_2O的排放特性

NO and N_2O Emission Characteristics of Oxy-Fuel Circulating Fluidized Bed Combustion

在50kW循环流化床燃烧试验台上对大同煤和神木半焦进行了O2／CO2气氛的富氧燃烧试验，试验的进口氧气体积分数为25％～50％，燃烧温度为800～950℃．试验研究的目标是获得燃烧温度、进口氧气体积分数和过量氧气系数等因素对循环流化床富氧燃烧过程中NO和N2O的排放特性以及燃料N转化率的影响．研究结果表明，与空气气氛相比，O2／CO2气氛下的燃料N转化率明显降低；随着进口氧气体积分数增加，NO的排放下降，而N2O的排放则升高；随着过量氧气系数的增加，NO、N2O的排放以及燃料N转化率均呈增加趋势．在循环流化床富氧燃烧中，提高燃烧温度、进口氧气体积分数以及降低过量氧气系数都能有效降低燃料N转化率，抑制氮氧化物的排放．

Experiments were carried out in a 50 kW circulating fluidized bed （CFB） combustor under the O2/CO2 at- mosphere. The combustion temperature was within the range of 800--950 ℃, and the inlet oxygen concentration was within the range of 25%--50%. The effects of combustion temperature, inlet oxygen concentration and excess oxy- gen coefficient on NO and N20 emission characteristics were studied. The results show that the N conversion rate un- der the O2/CO2 firing mode is much lower than that under the air firing mode. As the inlet oxygen concentration in- creases, the NO emission increases and while N2O emission decreases. With the increase of excess oxygen coefficient, both NO and N2O emissions and N conversion rate increase. It can be concluded that increasing tempera- ture and inlet oxygen concentration and decreasing excess oxygen coefficient are both beneficial to the decrease of N conversion rate oxy-fuel CFB combustion.