常压法测定煤层瓦斯含量的误差分析

Analysis on measurement error of gas content in coal seam by normal atmosphere method

为了校正脱气法和常压法测量瓦斯含量的误差。通过理论分析、模型计算和实验对比的方法,研究煤样气体自然成分含二元和三元混合气体时的误差来源。查明气体成分为N_2和CH_4时,该误差可通过系数法进行修正;气体成分含CO_2,CH_4和N_23种气体时,误差可通过扩展的langmuir模型修正。水分对测定误差的影响为:烟煤中含氧官能团与水优先结合后,影响煤孔网吸附点的可达性,导致水分与测定误差线性相关;无烟煤表面积大且表面官能团减少,水分的优先吸附使煤表面性质更均匀,水分与气体分子竞争煤表面的相同吸附点,水分与测定误差负相关。该结论对煤层瓦斯含量测定方法的选择和修正有重要意义。

In order to correct the measurement error of gas content by the degassing method and the normal atmosphere method,the error sources when the natural composition of coal sample gas contained the binary and ternary gas mixtures were studied through the methods of theoretical analysis,model calculation and experiment comparision.It was found that the error could be corrected by the coefficient method when the gas composition contained nitrogen and methane,and the error could be corrected by the extended langmuir model when the gas composition contained carbon dioxide,methane and nitrogen.The influence of moisture on the measurement error was that the preferential combination of oxygen-containing functional groups with water in the bituminous coal influenced the accessibility to the adsorption sites of coal borehole net,which caused the linear correlation of the moisture and the measurement error.The anthracite had a large surface area and less surface functional groups,and the preferential adsorption of moisture made the surface properties of coal more homogeneous,then the moisture and the gas molecules competed the same adsorption sites on the coal surface,so the moisture was negatively correlated with the measurement error.The results have important significance for the selection and correction for the measurement methods of gas content in coal seam.