甲烷/石松子粉尘混合体系爆炸下限的变化规律

Experimental investigation of the lower explosion limit of hybrid mixtures of methane and lycopodium dust

基于标准20 L球形爆炸装置,在相同测试条件下,分别测量了石松子粉尘、甲烷和不同浓度配比的甲烷/石松子粉尘混合体系爆炸下限,并将测试结果与Le Chatelier’s law、Bartknecht curve、Jiang method等混合体系爆炸下限预测结果进行了对比。结果表明:低于爆炸下限的甲烷和低于爆炸下限的石松子粉尘混合后仍具有爆炸危险性。石松子粉尘爆炸下限随混合体系中甲烷体积分数的增高而减小。Le Chatelier’s law、Bartknecht curve、Jiang method均不能准确预测甲烷/石松子粉尘混合体系爆炸下限。Le Chatelier’s law对甲烷体积分数φ与甲烷爆炸下限φ_L之比φ/φ_L<0.5的混合体系爆炸下限的预测值偏小,而对φ/φ_L>0.5的混合体系预测值偏大;Bartknecht curve在预测φ/φ_L>0.5的混合体系爆炸下限时适用性较好,而对于φ/φ_L<0.5的混合体系预测值偏小;Jiang method不适用于预测甲烷/石松子粉尘混合体系爆炸下限。

In this work,lower explosion limits of methane,lycopodium dust and methane-lycopodium dust hybrid mixtures were determined under the same testing conditions based on the 20 L sphere vessel. The measured results were compared with the values calculated by the Le Chatelier’s law,the Bartknecht curve and the Jiang method. The results showed that the combination of methane prepared in concentrations below its lower explosion limit and the lycopodium dust in concentrations below its minimum explosion concentration rate was still a mixture with a hazard of explosion. The minimum explosion concentration of lycopodium dust decreased with the increase of methane concentration in the hybrid mixtures. The lower explosion limit of methane-lycopodium dust hybrid mixtures couldn’t be accurately calculated by the Le Chatelier’s law,the Bartknecht curve or the Jiang method. The lower explosion limit of hybrid mixtures of methane and lycopodium dust calculated by the Le Chatelier’s law were smaller than the measured values for the mixtures with the methane concentration φ/φ_L〈0.5,but bigger for the mixtures with the methane concentration φ/φ_L〉 0.5. The Bartknecht curve was suitable for predicting the lower explosion limit of the hybrid mixtures with the methane concentration φ/φ_L〉0.5. But for the hybrid mixtures with a methane concentration φ/φ_L〈0.5,the calculated values were smaller than the measured ones,whereas the Jiang method was unsuitable for predicting the lower explosion limit of the hybrid mixtures of methane and lycopodium dust.