煤自燃灾害气体指标的阶段特征试验研究

为分析煤自燃早期气体指标变化特征规律,更好地解决煤矿现场灭火救灾决策问题,通过煤自燃程序升温试验,首先得到煤样气氛中O2,CO,CO2,CH4,C2H4和C2H6气体的体积分数随温度的变化规律。根据煤体温度,将煤自燃前期划分为5个阶段(潜伏、储热、蒸发、活跃和乏氧)。分析3种不同变质程度的煤样的气体指标在各阶段的变化特征。建立煤自燃气体指标与特征温度阶段区间的对应关系。结果表明:在自燃潜伏阶段,煤的变质程度越低,早期越易产生CO,越难产生CH4;在储热阶段,煤的变质程度越低,早期越易且越快产生C2H6;在蒸发阶段,煤内外在水分脱附,低变质煤的C2H4也随之产生;在活跃阶段,各种气体体积分数均有剧烈增高的趋势,较高变质煤的C2H4也随之产生;在乏氧阶段,O2体积分数低于15%,与O2体积分数相关指标(CO/ΔO2,CO/CO2等)趋势有所改变。

Temperature-programmed Experimental Study on Stage Characteristics of Coal Spontaneous Combustion Disaster Gas Indicators

In order to analyze the gas indicators variation in early phase of coal spontaneous combustion and make it better to solve the problem of mine site fire fighting and rescue decision-making,the relationships between the volume fractions of O2,CO,CO2,CH4,C2H4 or C2H6 and temperature were obtained by experiments on coal spontaneous combustion programmed heating.Based on coal temperature,the low temperature coal spontaneous combustion was divided into five stages (latent stage,the stage of thermal storage,evaporation stage,active stage,and the pan-oxygen stage).For three different ranks of coal samples,variations in indicator gases in the various stages were analyzed.The correspondence between coal spontaneous combustion indicator gas and the characteristic temperature interval was established.The results show that in the latent phase of the spontaneous combustion,the lower degree of metamorphism of coal,the easier to produce CO and the more difficult to produce methane in the early phase;in the heat storage stage,the lower degree of metamorphism of coal,the easier and faster to produce C2H6;in the evaporation stage,desorption of water in or on the coal takes place,and C2H4 was released consequently from lower rank coal;in the active stage,there is a strong trend towards a drametic increase in volume fractions of the gases,C2H4 was released from the higher metamorphic coal;in the hypoxic phase,oxygen volume fraction is lower than 15%,and the trend of the indicators (CO/ΔO2, CO/CO2,etc.) related with it will change.