湿烟气条件下丙烷在金属铁表面还原NO的特性

NO Reduction by Propane Over Iron in Wet Flue Gas

在N2气氛和模拟烟气气氛条件下,研究了水蒸气对丙烷在金属铁表面还原NO的影响.实验采用电加热的陶瓷管流动反应器进行,反应温度为3001 100℃.对反应后的铁样品的组分变化和表面微观结构变化进行了XRD和SEM分析.结果表明,水蒸气会使金属铁氧化,生成氧化铁.在N2氛围中,600850℃时水蒸气降低了丙烷在金属铁表面还原NO的效率.温度进一步升高后,铁被氧化后表面微观结构变得疏松多孔,从而使得NO气体能够进入孔隙内部进行反应,此时水蒸气对NO还原效率的削弱作用逐渐消失.在模拟烟气条件下,水蒸气有利于提高NO还原效率,特别是在贫燃料条件下.湿烟气条件下SO2对丙烷在金属铁表面还原NO的影响很小.在相同条件下丙烷在金属铁表面还原NO的效率与甲烷进行了比较.结果表明以丙烷为燃料在金属铁表面还原NO,不仅效率相对较高,而且可以节省燃料的体积流量.在富燃料条件下,如SR1=0.9时,在900℃时水蒸气体积含量为7.0%条件下,丙烷在金属铁表面还原NO的效率比甲烷高14%,而丙烷的用量只有甲烷的1/3.

The effect of water vapor on NO reduction by propane over iron was experimentally investigated in N2 and simulated flue gas atmosphere respectively.An electrically heated ceramic tubular flowing reactor was used to conduct the tests at 3001 100℃.The iron samples composition and surface microstructure changes were analyzed by XRD and SEM after the ractions.Results showed that water vapor oxidized iron to iron oxides.In N2 atmosphere,water vapor decreased the NO reduction efficiency at 600850℃.As the reaction temperature further increased,a porous surface was formed on the oxidized iron and NO could enter the pore to react with fresh iron,therefore,the negative effect of water vapor on NO reduction became weak.In simulated flue gas atmosphere,water vapor promoted NO reduction by propane over iron,especially in fuel-lean conditions.SO2 had very small effect on NO reduction in wet simulated flue gas atmosphere.NO reduction efficiencies by C3H8 over iron were compared to that by CH4 at the same conditions.Results showed that propane reduced NO at a higher efficiency and lower amount of the fuel,e.g.,at fuel rich condition,such as SR1=0.9,NO reduction by propane over iron was 14% higher than that by methane at 900℃,while the amount of propane was only 1/3 of that of methane when there was 7.0% water vapor.