页岩与煤岩等温吸附模型对比分析

Comparative Analysis of Isothermal Adsorption Models for Shales and Coals

采用Freundlich经验公式、Langmuir模型、扩展的Langmuir模型、Toth吸附模型和Langmuir-Freundlich吸附模型等5种单组分模型对煤与页岩CH4吸附实验数据进行拟合,分别检验了实验数据的拟合程度。结果表明,无论是煤岩还是页岩,三参模型拟合度均高于二参模型。二参模型中,Langmuir模型对煤岩与页岩拟合精度较高,约是Freundlich经验公式模型的8倍以上。三参模型拟合精度都很高,其中对于页岩来说,Langmuir-Freundlich模型在平均温度下的拟合度最好,扩展的Langmuir模型拟合度较差;对于煤岩来说恰恰相反,扩展的Langmuir模型拟合度最好,而Langmuir-Freundlich模型拟合度较差。总体来看,页岩与煤岩分别对Langmuir-Freundlich模型、扩展的Langmuir模型拟合最好,Freundlich经验公式拟合最差。研究结果对煤岩与页岩等温吸附模型的精确选择具有一定的指导意义。

The experimental data of CH4 adsorption on coals and shales are fitted by using Freundlich empirical formula, Langmuir model, extended Langmuir model, Toth adsorption model and Langmuir-Freundlich adsorption model. The fitting degrees is also examined. The results show that both the coal and the shale, the fitting precision of three-parameter model is higher than that of two-parameter model. For the twoarameter models, the fitting degrees of Langmuir model on coal and shale is much higher than the Freundlich empirical formula model by more than 8 times. For the three-parameter models, their fitting degrees are all higher, of which Toth model is the highest in fitting degree than E-F and L-F models at an averge temperature for shales, but for coals, it is lower than the other two. On the whole, Toth model and L-F model are better for fitting of coals and shales rather than Freundlich empirical formula. The study results are of guiding significance in proper selection of isothermal adsorption model for coals and shales.