CO2惰化抑制矿井伴生油型气燃爆特性与机理

    Characteristics and mechanism of mine-associated oil-type gas explosion suppressed by CO2 inerting

    • 摘要: 为揭示矿井伴生油型气燃爆危险性及其惰化特征,采用实验测试、数值计算和理论分析相结合的方法系统研究了CO2惰化抑制矿井伴生油型气燃爆特性与机理。利用20 L球形爆炸测试系统测量了油型气爆炸极限、爆炸压力以及CO2惰化下的爆炸压力特征和临界抑爆体积分数,并基于USC Mech 2.0模型分析了CO2惰化作用下油型气爆炸绝热火焰温度分布规律及反应动力学机理。研究结果表明:所测油型气的爆炸下限仅为4.55%,Le Chatelier模型可较为准确地预测油型气的可燃下限,但对于可燃上限的预测结果相较实验值减少了55.84%;所测爆炸极限范围内,油型气爆炸超压峰值和最大爆炸超压速率分别为0.79 MPa 和25 MPa/s,相对应的持续燃烧时间tc和快速燃爆时间tb分别为127.6 ms和93.2 ms;随着油型气当量比的增加,其完全惰化所需的CO2临界抑爆体积分数呈现下降趋势。当量比为1.4时,CO2临界抑爆体积分数为8%,较当量比为1.0时的临量抑爆体积分数(23%)减少了65.21%。CO2的添加对油型气层流燃烧速度和绝热火焰温度均有抑制作用,其降低了化学反应速率,导致宏观压力参数的降低,抑爆效果随着当量比的增加而增大。CO2体积分数的增加导致混合体系绝热火焰温度和关键基元反应热释放速率降低,同时也导致混合体系燃爆过程中H、O、OH等关键自由基浓度降低,从而产生惰化作用。

       

      Abstract: To reveal the explosion risk and inerting characteristics of mine-associated oil-type gas, this study systematically investigates the properties and mechanisms of carbon dioxide (CO2) in suppressing the explosion of mine-associated oil-type gas by combining experimental tests, numerical calculations and theoretical analysis. A 20 L spherical explosion test system was adopted to determine the explosion limits and explosion pressure of oil-type gas, as well as the variation of explosion pressure and critical inerting volume fraction under CO2 inerting. Based on the USC Mech 2.0 model, the distribution of adiabatic flame temperature and reaction kinetic mechanism of oil-type gas explosion under CO2 inerting were analyzed. The results show that the lower explosion limit of the tested oil-type gas is only 4.55%. The Le Chatelier model can accurately predict the lower flammability limit, while the predicted upper flammability limit is 55.84% lower than the experimental value. Within the measured explosion limit range, the peak overpressure and maximum overpressure rise rate of oil-type gas reach 0.79 MPa and 25 MPa/s, respectively. The corresponding total combustion duration tc and rapid explosion duration tb are 127.6 ms and 93.2 ms. With the increase of the equivalence ratio of oil-type gas, the critical inerting volume fraction of CO2 required for complete explosion suppression decreases. When the equivalence ratio is 1.4, the critical explosion-suppression volume fraction of CO2 is 8%, which is 65.21% lower than the value(the critical explosion-suppression volume fraction of 23%) at an equivalence ratio of 1.0. The addition of CO2 inhibits the laminar burning velocity and adiabatic flame temperature of oil-type gas, reduces the chemical reaction rate and macroscopic pressure parameters, and the explosion suppression effect is enhanced with the rise of equivalence ratio. Increasing CO2 concentration lowers the adiabatic flame temperature and heat release rate of key elementary reactions of the mixture, and also leads to a decrease in concentration of critical free radicals such as H, O and OH during explosion, thereby achieving the inerting effect.

       

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