Experimental investigation on residual gas re-explosion behaviors following primary fuel-rich explosions of methane-bituminous coal powder mixtures

This study aims to identify the re-explosion hazard after a primary explosion of a fuel-rich methane and bituminous coal powder mixture. Primary and re-explosion experiments were conducted using a spherical explosion testing apparatus. The results reveal that once the mixture of methane and bituminous coal powder reaches a certain degree of fuel enrichment, an explosion can occur under the condition of reintroducing a certain volume of air and igniting. However, the pressure rise rate and explosion pressure of re-explosions are both lower than those recorded in the primary explosion. Nonetheless, the residual gas re-explosion exhibits a maximum pressure exceeding 0.3 MPa, with the maximum rate of pressure rise surpassing 1.8 MPa/s. The residual gas mixture with explosibility significantly reduces the lower explosion limit of methane and increases the risk of re-explosion. The re-explosion characteristics exhibited significant variations with the changing re-added methane concentration after a primary explosion. The premixed laminar burning velocity and flame temperature followed consistent trends with the explosion characteristic parameters. Furthermore, the key elementary reactions governing the combustion kinetics were identified. The results provide new insights into the re-explosion phenomenon and provide data support for assessing the hazards of a re-explosion accident in coal mines.

本研究旨在探明富燃料甲烷与烟煤粉混合物一次爆炸后的复爆（re-explosion）危险性。本研究采用球形爆炸测试装置，开展了一次爆炸与复爆实验。结果显示，当甲烷与烟煤粉混合物达到一定燃料富集程度时，重新引入一定体积的空气并实施点火，即可引发爆炸。但复爆的压力上升速率与爆炸压力均低于一次爆炸工况下的测试结果。尽管如此，残余气体复爆的最大压力仍可超过0.3 MPa，最大压力上升速率突破1.8 MPa/s。具备爆炸性的残余混合气体可显著降低甲烷的爆炸下限，提升复爆风险。一次爆炸后，随重新添加的甲烷浓度变化，复爆特性会出现显著差异。预混层流燃烧速度与火焰温度的变化趋势与爆炸特征参数保持一致。此外，本研究明确了控制燃烧动力学过程的关键基元反应。上述研究结果为复爆现象提供了全新的认知视角，并为煤矿复爆事故的危险性评估提供了数据支撑。