甲烷体积分数对甲烷-煤粉复合火焰传播特性的影响

为探究甲烷体积分数对煤粉爆炸过程的影响,并掌握甲烷-煤粉爆炸火焰传播特征,通过粒度分析仪和同步热分析仪研究2种煤粉样品的粒径大小和热解过程。利用1500 mm×80 mm×80 mm的半开口竖直燃烧管道,探究不同甲烷体积分数下,中位粒径分别为65和25μm烟煤粉的火焰传播特性,分析甲烷体积分数对甲烷-煤粉复合火焰结构、温度和速度的影响。结果表明:25μm煤粉比65μm煤粉的火焰更加明亮,甲烷体积分数的增加对65μm煤粉火焰有更强的促进作用;当甲烷体积分数越接近当量比时,火焰锋面越规则,火焰速度也越快;随着甲烷体积分数的增加,火焰温度和火焰传播速度均呈现先增大后减小的趋势;甲烷体积分数为9%时,火焰温度达到最大值;甲烷体积分数为8%和10%时,65和25μm煤粉最大火焰速度为分别为26.53和39.28 m/s。

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 explosion,particle size and pyrolysis process of two kinds of coal powder samples were studied by a particle size analyzer and a synchronous thermal analyzer.Then,a 1500 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 25μm for different methane volume fractions on structure,temperature and velocity of methane-coal dust compound flame.The results show that coal flame for 25μm is brighter than that for65μm,and increase in methane volume fraction has a stronger promotion effect on 65μm coal dust flame.When volume fraction approaches the equivalence ratio,the more regular flame front is,the greater flame velocity is.And as it increases,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%,and the maximum flame velocity of 65 and 25μm pulverized coal are 26.53 and 39.28 m/s when it is 8%and 10%respectively.