煤体纳米级孔隙低温氮吸附特征及分形性研究

Study on adsorption characteristics and fractal properties of nano-scale pores at low temperature coal

为了研究不同煤级煤体纳米级孔隙结构特性,通过低温氮吸附法对宿州邹庄矿、平顶山八矿、鹤壁九矿的8组煤样进行对比实验,分析了煤孔隙结构特性,并运用孔隙分形几何学理论基础建立FHH模型,揭示了煤的变质程度和破坏程度对煤孔隙结构差异的影响。结果表明:(1)不同变质程度的煤,其吸附能力与变质程度并不呈线性关系,与共生原生结构煤相比,构造煤的平均孔径普遍较小,但其孔比表面积较大,且构造煤吸附能力明显强于原生结构煤。(2)不同煤级煤的分形维数D大小并不随着煤化程度的升高而呈规律性的线性变化,构造变形作用促使构造煤孔隙结构复杂化。(3)分形维数D越大,表明煤体孔隙结构越复杂,煤体孔比表面积及其吸附量也较大。(4)分形维数与平均孔径呈反比。

In order to study the nanoscale pore structure characteristics of different rank coal body structure,low-temperature nitrogen adsorption method was used to make contrast experiment on eight groups of coal samples which came from Suzhou Zouzhuang mine,Pingdingshan 8th mine and Hebi 9th mine,then the characteristics of coal pore structure were analyzed successfully; meanwhile,by using pore FHH model basis of fractal geometry theory,the impact was revealed on the coal pore structure difference of the coal metamorphic degree and extent of damage. The results show that：（ 1） for different metamorphic degree of coal,the link of adsorption capacity and metamorphic degree is not a linear relationship; compared with the symbiotic native structure of coal,the average aperture of tectonic coal is generally small,but the pore specific surface area is larger,and the adsorption capacity of tectonic coal is significantly stronger than the original structure of coal.（ 2） for different rank coal,its fractal dimension D of doesn＇t increase linearly with the degree of coalification; tectonic deformation effect prompts tectonic coal pore structure to be more complicated.（ 3） the bigger fractal dimension D is,the more complex the pore structure of coal shows,and the greater the coal pore specific surface area and adsorption capacity.（ 4） fractal dimension is inversely proportional with the average pore diameter.