粒径对地下煤炭正向阴燃蔓延速率影响试验研究

Experimental Study on the Influence of Particle Size on Forward Smoldering Spread Rate of Underground Coal

针对地下煤炭阴燃火灾特点,研究了粒径为0.15~1.70mm的3种不同变质程度煤样水平正向阴燃传播规律。试验结果表明:粒径减小导致>10nm孔隙的比例最高增加了34.0%,比表面积最高增加了30.0%,孔体积最高增加了78.8%,粒径减小促进了煤的阴燃;不同煤种在25.0~800.0℃之间呈现4个差异化燃烧阶段,随着粒径减小燃烧失重阶段的活化能降低了5.7%~16.1%;维持单位质量煤体阴燃的最低供气流量为0.13~0.20m^(3)·h^(-1)·kg^(-1),且粒径越小数据越低;平均阴燃峰值温度分别为427.0~489.7℃(云南褐煤),543.1~675℃(山西无烟煤),608.0~696.0℃(山西烟煤),这3种煤的平均阴燃蔓延速率大小依次升高,且主要受炭氧化温度影响;平均阴燃峰值温度和平均阴燃蔓延速率均与粒径呈现显著负相关关系。

According to the characteristics of underground coal smoldering fire, the horizontal spread laws of forward smoldering were investigated on three types of coals(particle sizes of 0.15~1.70 mm) with different ranks. The results show that, with the decrease of particle size, the proportion of coal with pores larger than 10 nm increases by 34.0% at the maximum, the specific surface area increases by 30.0% at a maximum, and the pore volume increases by 78.8% at the maximum. It is indicated that reducing the particle size can promote the smoldering of coal. Different types of coal samples show four distinct combustion stages between 25.0℃ and 800.0℃. With the decrease of particle size, the activation energy decreases by 5.7%~16.1% in the combustion weightlessness stage. The minimum air-supply to maintain smoldering of unit mass coal is 0.13~0.20 m^(3)·h^(-1)·kg^(-1), and the smaller the particle size, the lower the value. The average smoldering peak temperatures are at 427.0~489.7℃ for Yunnan lignite, at 543.1~675℃ for Shanxi anthracite, and at 608.0~696.0℃ for Shanxi bituminous coal. The average smoldering spread rates of above three types of coal increase in turn, and are mainly affected by the char-oxidation temperature. The average smoldering peak temperatures and average smoldering spread rates are negatively correlated with particle size.