基于低温氮吸附的煤孔隙分布多重分形表征

Multifractal Characterization of Low-temperature Nitrogen Adsorption for Pore Distribution of Coal

基于低温氮吸附曲线,采用多重分形理论分析了低挥发分烟煤孔隙分布的非均质性,探讨了显微组分对煤孔隙非均质性分布的影响。结果表明:广义分形维数Dq随着阶数q的增大而减小,说明煤的低温氮孔隙分布具多重分形特征,但不同显微组分含量的煤孔隙分布的多重分形程度存在差异;相比富镜质组煤,富惰质组煤的Dq谱左锋宽度D-5-D0变小,但信息维数D1和长程相关指数H增大。上述结果表明随着惰质组含量的升高,煤孔隙结构趋于简单,孔隙团聚特征减弱,孔隙连通性增强,导致孔隙分布非均质性减弱;对于同一煤阶,D1、H和D-5-D0是区分不同显微组分含量的煤孔隙非均质性差异演化的主要指标。

In this paper,multifractal analysis from low-temperature nitrogen adsorption isotherm was employed to analyze the heterogeneity of pore distribution of low-volatile bituminous coal,and the effect of macreal composition on the distribution of pore heterogeneity was discussed.The results show that the generalized dimension Dqdecrease as q increases,demonstrating a multifractal behavior of pore distribution of coal derived from low-temperature nitrogen adsorption.However,the degree of multifractality shows differences among coal with various maceral composition.In comparison of vitrinite-rich coals,the Dqvalues of the width of left side D-5-D0 of inertinite-rich coals decrease while the values of information dimension D1 and Hurst exponent H increase.The above results show that with the increasing inertinite,the pore structure becomes simple,the clustering of pores decreases,the pore connectivity increases,resulting in the reductionin heterogeneity of pore distribution.For the same rank coal,the D1,H and D-5-D0 are the major indexes to differentiate between heterogeneity of pore distribution of coal with different maceral composition.