O_2/CO_2气氛下氮反应机理的研究

Research on reaction mechanism of nitrogen in O_2/CO_2

选取CH4、O2、CO2、Ar、NO、NH3等气体,作为混合气和煤粉一起送入一维沉降炉内,以模拟O2CO2气氛下煤中燃料氮、循环NO以及二者的相互作用对NO排放的影响.结果显示,在还原性气氛下NH3、HCN、CH4、CO与循环NO间的反应是NO排放下降的主要因素,且煤焦与NO的异相反应、吸附反应对NO的降解效果要明显高于氧化性气氛,同时,CO2体积分数的增加使得燃料中氮的氧化率升高,循环NO的降解率下降;氧化性气氛下随CO2体积分数的增加,燃料中氮的氧化率也增加,但循环NO的降解率升高.当CO2体积分数不变时,其对NO降解的作用随循环NO体积分数的增加愈加明显,在循环NO也不变且CO2体积分数较低时,随过量空气系数的增加,循环NO的降解率下降,而CO2体积分数较高时则出现相反情况.

The experiment sends gases mixture, which includes CH4, O2 , CO2, Ar, NO, NH3, and coal into one dimension drop-tube furnace to simulate coal combustion in O2/CO2 . The effect of fuel nitrogen recycled NO concentration and their interactions on NO emission are discussed respectively. The experiment result shows in reducing mood the homogeneous reaction between NH3 , HCN, CH4, CO and recycled NO are major factors that can decrease NO emission when coal combusts in O2/CO2. And the heterogeneous reaction and adsorption reaction of carbon and NO have a better effect than in oxidization atmosphere. With the concentration of CO2 increasing, oxidization ratio of fuel nitrogen increase but the reduction ratio of recycled NO decrease in oxidization atmosphere and increase in reducing atmosphere. When concentration of CO2 keeps at a constant, the effect of NO deoxidization increase with the concentration of recycled NO increasing. When concentration of recycled NO keeps at a constant, with the excess air ratio increasing, low concentration of CO2 is more favorable for NO deoxidization, but high concentration of CO2 has negative effect on NO deoxidization.