低阶煤孔隙结构特征及其对瓦斯吸附的影响

Pore structure characteristics of low rank coal and their influence on gas adsorption

为分析低阶煤孔隙结构特征及其对瓦斯(甲烷)吸附特性的影响,采用高压容量吸附装置对3个低阶煤煤样和一个高阶煤煤样进行等温吸附试验和低温液氮吸附试验,并对比分析不同变质程度煤的吸附性能和孔隙结构。结果表明:低阶煤的吸附特性符合朗缪尔(Langmuir)方程;不同变质程度煤孔的结构存在明显差异,不同低阶煤的孔隙结构基本相近,在高压段均出现微小的滞后环,其孔形以两端开口的楔形孔为主,其对瓦斯的吸附主要集中于中孔和微孔中,中孔占比更大;煤体孔隙比表面积决定瓦斯吸附能力,中孔的比表面积与煤样的Langmuir体积线性相关,对吸附起决定性作用,而微孔的比表面积与Langmuir体积没有明显的正相关关系。

For the sake of analyzing pore structure characteristics of low rank coal and their influence on gas methane adsorption,gas adsorption experiments and low temperature liquid nitrogen adsorption experiments were done with three low and one high rank coal samples by using a high capacity adsorption device.Adsorption properties and pore structure characteristics of the samples were analyzed comparatively. Experimental results show that the adsorption capacity of low rank coal would increase quickly with the increase in gas pressure at lower pressure,but its increasing speed becomes flat at higher pressure,that the pore structure characteristics have important effects on gas adsorption that there are great differences among the pore structural characteristics of different low rank coal samples,that pore structure characteristics of different low rank coal samples are near to each other,that the wedges with opening at both ends are predominant shape of the pores,that the mesopores and microspores are the main carrier of low rank coal adsorbed gas and the mesopores have a bigger contribution,and that a linear correlation exists between mesopores surface area and coal Langmuir volume