松散煤体内气体渗流特征研究

    Study on gas seepage characteristics of loose coal

    • 摘要: 为研究温度对采空区松散煤体内气体渗流规律的影响,利用自主研发的松散煤体温度−渗流综合实验平台,对不同温度条件下的无烟煤、烟煤、褐煤进行了气体渗流特性实验;采用COMSOL Multiphysics模拟了在恒温及连续升温状态下通过烟煤的气体渗流过程;通过研究采空区松散煤体中存在局部热源时的气体渗流规律,建立了基于温度的松散煤体气体渗流模型。结果表明:在30~80 ℃恒温条件下,空气以低于1.0 cm/s的速度通过松散破碎的无烟煤、烟煤及褐煤时均遵循线性达西渗流定律,压力梯度随比流量的增加逐渐增大;煤体渗透率随温度升高而降低,不同煤样的渗透率随温度升高的变化幅度不同,且褐煤>烟煤>无烟煤;随温度升高,煤柱内温度与渗透率分布可近似视为靠近出气端的“椭球形壳体”。

       

      Abstract: In order to study the influence of temperature on the gas seepage law in loose coal bodies in goaf, gas seepage characteristics experiments were conducted on three types of coal samples, namely anthracite, bituminous coal, and lignite, under different temperature conditions using a self-developed loose coal temperature seepage comprehensive experimental platform, and COMSOL Multiphysics was used to simulate the gas seepage process through bituminous coal under constant temperature and continuous heating conditions. By studying the gas seepage law when there is a local heat source in the loose coal body in the goaf, a temperature based on gas seepage model for the loose coal body was established. Under constant temperature conditions ranging from 30 ℃ to 80 ℃, when air passes through loose and broken anthracite, bituminous coal, and lignite at a speed of less than 1.0 cm/s, it follows the linear Darcy flow law, and the pressure gradient gradually increases with the increase of specific flow rate; the permeability of coal decreases with increasing temperature, and the permeability changes of different coal samples vary with increasing temperature, and brown coal>bituminous coal>anthracite; as the temperature increases, the temperature distribution and permeability distribution inside the coal pillar can be approximated as an “ellipsoidal shell” near the gas outlet.

       

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