单颗粒煤挥发分火焰碳烟演化实验研究

Experimental Study on Soot Evolution of Single Coal Particle Volatile Flame

搭建单颗粒煤燃烧检测平台,进行了单颗粒煤挥发分火焰中碳烟生成的检测研究。基于高速摄像仪检测得到的碳烟体积分数分布,结合热泳探针技术和扫描电子显微镜对挥发分火焰中碳烟颗粒的形貌进行分析,探究了单颗粒煤挥发分火焰中碳烟分布特征及演化过程。结果表明:在稳定燃烧阶段,最大碳烟体积分数出现在尾焰低温区,且相同燃烧条件下烟煤的碳烟体积分数较高;挥发分火焰的初期碳烟分散在焦油中,伴随焦油被消耗,碳烟颗粒由簇状团聚为尺寸更大的链状;成熟碳烟颗粒团聚物中,大同烟煤和神华烟煤燃烧生成的碳烟形貌参数相近,印尼褐煤燃烧生成的碳烟平均主颗粒粒径小、分形前置因子最大,团聚结构更紧凑。

A single coal particle combustion platform was built and the detection of soot formation in the single coal particle volatile flame was experimentally investigated.The distribution of the soot volume fraction was obtained by using the high-speed camera and the morphology of the soot in the volatile flame was analyzed through the thermophoretic sampling technology and scanning electron microscope,which were used for exploring the soot distribution characteristics and the evolution process in the single coal particle volatile flame.Based on the results,it is found that the maximum soot volume fraction appears in the tail flame region where the temperature is relatively low during the stable combustion,and bituminous coals have the highest soot volume fraction under the same burning conditions.Furthermore,the initial soot disperses in the tar and then soot particles aggregate from the cluster-shaped to larger chain-shaped state as the tar is consumed.Besides,the morphology parameters of the soot produced by two kinds of bituminous coals are similar in the mature soot aggregates,and the agglomeration structure of the soot produced by Indonesia lignite combustion is more compact between the two bituminous coals,which has the smallest average primary particle diameter and the biggest fractal prefactor.