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为了从数学模型上深入了解煤层气在煤中吸附的物理机理,利用参数具有物理意义的吸附模型,如Langmuir、Freundlich、Toth、Langmuir-Freundlich、扩展的Langmuir、BET、D-R、D-A模型,分别对3个不同煤级样品的空气干燥基和干燥无灰基甲烷等温吸附数据进行拟合,对BET模型、D-R模型、D-A模型中涉及的p0,采用虚拟饱和蒸气压的概念,用3种方法计算。通过对模型参数拟合值的分析,比较了空气干燥基和干燥无灰基煤的吸附特征,对微观吸附机理进行了解释。比较了各模型对单煤级和3个煤级作为整体的拟合效果,认为B-BET-1模型、B-BET-2模型对于3个煤级样品均没有物理意义,D-R-3模型和D-A-3模型不能用于描述长焰煤的吸附特性,T-BET-3模型异常高的最大吸附量所反映的吸附机理尚待研究。综合分析,认为T、L-F、E-L、B-BET-3、TBET-1和T-BET-2模型用于描述煤中甲烷超临界吸附较为理想。
In order to understand the physical mechanism of CBM adsorption in coal from the mathematical model, the physical model of adsorption, such as Langmuir, Freundlich, Toth, Langmuir-Freundlich and extended Langmuir, BET, DR, Three different coal-level samples were air-dried and dry ash-free methane methane adsorption isotherm data fitting, for the BET model, DR model, DA model involved p0, the concept of virtual saturated vapor pressure, calculated by three methods . Through the analysis of fitting values of the model parameters, the adsorption characteristics of air-dried and dry ash-free coal are compared, and the microscopic adsorption mechanism is explained. Comparing the fitting results of each model with single coal grade and three coal grades as a whole, it is concluded that the B-BET-1 model and the B-BET-2 model have no physical meaning for the three coal grade samples. The DR-3 model and The DA-3 model can not be used to describe the adsorption characteristics of long-flame coal. The adsorption mechanism reflected by the abnormally high maximum adsorption capacity of T-BET-3 model is yet to be studied. The T, L-F, E-L, B-BET-3, TBET-1 and T-BET-2 models are all considered to be ideal for describing the supercritical methane adsorption in coal.