基于封闭耗氧实验的窒熄带氧临界体积分数研究

为更准确划分采空区自燃带与窒熄带,提出根据不同煤质的耗氧特点,用封闭耗氧实验确定采空区窒熄带临界氧气体积分数的新方法。在采空区煤自燃氧化升温热平衡条件下,分析煤自燃的耗氧速度、氧气体积分数和氧化放热的一致性特征,利用研制的煤样封闭耗氧实验装置,采集煤氧化实验过程中氧气体积分数呈衰减变化的连续检测数据,由数据变化曲线求氧气体积分数变化差商,获得煤在不同氧气体积分数下的耗氧速度,建立耗氧速度与氧气体积分数的量化关系,即γ-c(τ)图,由此确定窒熄临界氧气体积分数。分别对不同煤样做实验测定,得出长平矿3号煤层(无烟煤)窒熄带临界氧气体积分数为14.2%,九道岭矿4号煤层(烟煤)的窒熄带临界氧气体积分数为6.8%,晓南矿7号煤层烟煤的窒熄带临界氧气体积分数为8.2%。新方法按不同的煤种和煤质,依据各自不同的耗氧特性,来确定自燃带与窒熄带的划界标准,且与工程实际相符合。

Critical oxygen volume fraction of smothering quenched zone based on closed oxygen consumption experiment

In order to accurately divide the goaf spontaneous three zones,a new method of determining the oxygen concentration of goaf with closed oxygen consumption experiment was put forward according to the oxygen consumption characteristics of different coals.The thermal equilibrium condition of coal oxidation temperature in goaf and its consistency with oxygen consumption rate and oxygen concentration at the lowest temperature were analyzed.Using the self-developed closed oxygen consumption experimental device,the data of attenuation characteristics of coal oxygen concentration in the device were collected,using the oxygen concentration changes of oxygen consumption rate of coal difference quotient obtained at different oxygen concentrations.The critical oxygen concentration was determined according to the quantitative relationship between oxygen consumption rate and oxygen concentration.The experiment was carried out on anthracite and spontaneous combustion bituminous coal.The critical oxygen concentration of anthracite in the No.3 coal seam of Changping Mine is 14.2%,the critical oxygen concentration of the bituminous coal in the No.4 coal seam of Jiudaoling Mine is 6.8%,and the critical oxygen concentration of bituminous coal in the No.7 coal seam of Xiaonan Mine is 8.2%.New method determines the demarcation criteria between the spontaneous zone and suffocation zone according to different coals and coal quality,and based on the different characteristics of oxygen consumption,which is in agreement with the practice in fire engineering.