取芯过程中煤芯温度分布特征模拟研究

Simulation study on temperature distribution characteristics of coal core in core-taking process

针对取芯过程瓦斯解吸受煤芯的温度影响不明,造成煤层瓦斯含量测不准的问题,开展对取芯过程煤芯温度分布特征研究。采用自主研制的取芯管自动测温装置在赵固二矿原生结构煤层(f=1.71)进行深度20 m的取芯试验,获得取芯管管壁温升变化规律,变化曲线分为4个阶段:缓慢上升、加速上升、减速上升、缓慢下降阶段;应用COMSOL建立含瓦斯煤传热模型,将管壁的温度变化设置为边界条件,模拟取芯过程煤芯与管壁之间的热交换。结果表明:在取芯时间30 min内,煤芯平均温度快速上升,之后上升速度趋于平稳;在煤芯内,相同时刻,等间距的轴向与径向距离,径向较轴向的温度梯度较大,径向传导快于轴向传导;取芯过程煤芯径向温度Ta与径向距离d、时间t满足指数函数关系。研究结果可为测定取芯过程煤芯的瓦斯损失量提供参考依据。

Based on the problem that the influence of coal core temperature on the gas desorption in the core-taking process is not clear,which leads to the inaccurate measurement of gas content in coal seam,the distribution characteristics of coal core temperature in the core-taking process were studied.Relying on the self-developed automatic temperature measuring device of core-taking pipe,the core-taking test with a depth of 20 m in the primary structure coal seam(f=1.71)of Zhaogu No.2 coal mine was carried out,and the variation laws of temperature rise on the core-taking pipe wall were obtained.The variation curve was divided into four stages,including the slow rise,accelerated rise,decelerated rise and slow decline.The COMSOL was applied to establish the heat transfer model of coal containing gas,and the temperature change of pipe wall was set as the boundary condition to simulate the heat exchange between coal core and pipe wall during the core-taking process.The results showed that the average temperature of coal core rose rapidly within 30 min of core-taking time,and then the rising speed tended to be stable.At the same time,the temperature gradient in coal core in the radial direction was larger than that of axial direction under the equally spaced axial and radial distances,and the radial conduction was faster than the axial conduction.The radial temperature of coal core in the core-taking process satisfied the exponential function relationship with the radial distance d and time t.The results provide a reference for the determination of gas loss in coal core during the core-taking process.