沁水盆地南部中高阶煤高压甲烷吸附行为

High pressure methane adsorption of medium and high-rank coal in southern Qinshui basin

煤层气吸附作用是发生在煤基质内表面的物理过程,而煤岩复杂孔裂隙网络为高压甲烷吸附提供了丰富的空间。开展沁水盆地南部高阶煤30℃高压甲烷等温吸附实验,结合煤岩煤质参数与孔隙特征参数,通过改进的D-R模型分析了煤岩性质、孔隙特征与吸附参数的相关性。煤岩性质对最大吸附能力和吸附热参数的影响是多因素叠加的综合效应,而最大吸附能力与微孔体积,吸附体积校正参数与大中孔比表面积呈较好的正相关性,表明甲烷分子在煤基质内表面会根据孔径尺度大小呈现不同的吸附方式。据此提出高压甲烷在煤基质微孔中呈紧密堆积状态而在大中孔中呈多层分子堆叠状态的新认识,为进一步研究煤层气吸附机理提供了新的思路。

Methane adsorption is a physical process occurring in the inner-surface of coal pores.The pore network in coals provides plenty of accommodation for medium and high-pressure methane adsorption.In this study,we conducted high-pressure methane adsorption on southern Qinshui medium and high rank coals.We further discuss the relationship between adsorption parameters obtained from modified D-R model and coal properties and porosity characters.The results indicate that the effect of coal properties on the maximum adsorption capacity and heat of adsorption is a multi-factor-related superimposition.There is a discernible positive correlation between the maximum adsorption capacity with micropore volume and the revised parameter of adsorption amount with specific surface area of macro-mesopore.Methane molecule may display different adsorption behavior according to the pore width on the coal inner surface.On the basis of above observations,a primary understanding of high-pressure methane adsorption in relation to different pore width was proposed,which may provide a new insight of methane adsorption mechanism.