煤焦的微观结构对N_2O的生成与分解特性的影响

The Influence of Microscopic Structure Properties of Coal Char on N 2O Formation and Destruction

选取５种煤焦，在一个小型循环流化床上进行燃烧，研究Ｎ２Ｏ的生成，并就这几种煤焦对Ｎ２Ｏ的分解特性进行了实验，用液氮吸附法对５种煤焦的微观结构进行了分析，就Ｎ２Ｏ在煤焦内部的扩散机理、煤焦的微观特性对煤焦燃烧生成Ｎ２Ｏ或分解Ｎ２Ｏ的特性的影响进行了分析和讨论。研究表明，煤焦的比表面积和孔容积越大，煤焦燃烧生成Ｎ２Ｏ的氮转化率及煤焦分解Ｎ２Ｏ的能力都增大，影响煤焦反应能力的主要是小孔。Ｎ２Ｏ在煤焦内部的分子扩散通量大于努森扩散通量，大孔内的分子扩散是Ｎ２Ｏ在煤焦内部扩散的主要形式。化学反应比扩散对煤焦有关Ｎ２Ｏ的总反应特性的影响更大。

Five chars were used to investigate the formation of N 2O during combustion in a bench scale circulating fluidized bed.Reduction effects of these chars on N 2O were also studied.The microscopic structure properties of five chars were measured by means of liquid nitrogen absoption.The diffusion mechanism of N 2O inside char particles and the influence of coal char microscopic structure on N 2O formation and destruction were analyzed and discussed.The results showed that the larger the specific surface area and pore volume,the higher the fuel N conversion into N 2O and the stronger the ability of char to destruct N 2O during char combustion.It was the small pores which principally affected the reactivities of coal chars.The molecular diffusion flux of N 2O inside char particles was much greater than the Nusen diffusion flux of N 2O inside char particles.The diffusion of N 2O inside char particles was principally molecular diffusion inside large pores.Besides that,chemical reactions had stronger effects on the general reactivities of chars than diffusion did.