Impacts of methane content on compound flame propagation characteristics of methane-coal dust

In order to explore impacts of methane content on coal explosion process and to master flame propagation law of coal ̄methane explosionꎬ particle size and pyrolysis process of two kinds of coal powder samples were studied by a particle size analyzer and a synchronous thermal analyzer. Thenꎬ a 1 500 mm× 80 mm× 80 mm semi ̄open vertical combustion pipe was used to analyze impacts of coal powder at median particle size of 65 and 25 μm for different methane volume fractions on structureꎬ temperature and velocity of methane ̄coal dust compound flame. The results show that coal flame for 25 μm is brighter than that for 65 μmꎬ and increase in methane volume fraction has a stronger promotion effect on 65 μm coal dust flame. When volume fraction approaches the equivalence ratioꎬ the more regular flame front isꎬ the greater flame velocity is. And as it increasesꎬ both flame temperature and velocity show a trend of increasing first and then decreasing. Flame temperature reaches the maximum value at the content of 9%ꎬ and the maximum 第 6 期 刘静等: 甲烷体积分数对甲烷-煤粉复合火焰传播特性的影响 flame velocity of 65 and 25 μm pulverized coal are 26􀆰 53 and 39􀆰 28 m / s when it is 8% and 10% respectively.