富氧燃烧条件下煤焦的燃尽特性

Burnout Characteristic of Coal Chars Under Oxyfuel Combustion Conditions

本文利用平面火焰携带流反应器研究了DT烟煤在富氧燃烧条件下的燃烧实验。采用灰示踪法分析煤焦的燃尽和元素释放特性,并采用等密度模型计算了基于氧化反应C+0.5O_2→CO的表观反应动力学参数。研究结果表明;煤粉在富氧燃烧条件下的燃尽慢于空气燃烧;富氧燃烧条件下,煤焦与CO_2的气化反应会导致煤焦表面对O的化学吸附,进而导致氧元素释放速率减慢;高氧浓度条件下,高浓度CO_2对煤焦燃尽的抑制作用大于CO_2气化反应对煤焦燃尽的促进作用,降低环境氧浓度可以逐步提高CO_2气化反应对煤焦燃尽的贡献。

Burnout experiments of DT bituminous coal in oxyfuel combustion conditions were conducted in the flat-flame assisted entrained flow reactor.Ash tracer method was used to analysis the char burnout and element release behaviors.And the apparent reaction kinetic parameters based on the char oxidation reaction(C+0.5O_2 →CO) solved from the burnout curves using the shrinking core model.The results indicated that the reaction rate of pulverized coal under oxyfuel combustion condition was slower than that under air combustion condition.The oxygen atoms chemically adsorbed on char surface,resulted by the char-CO_2 gasification reaction,leads the reduction of release rate of oxygen element.The suppression effect of high content CO_2 on char burnout is more than promotion effect of CO_2 gasification reaction on char consumption at the high oxygen condition.The contribution of CO_2 gasification reaction on char consumption can be enhanced through reducing the oxygen concentration.