中高阶煤孔隙结构的演化规律研究

Study on Evolution of Pore Structure of Medium and High Rank Coals

为研究中高阶煤的孔隙结构特征的演化规律,采用低温液氮吸附法,结合FHH分形理论模型,探讨不同煤阶煤的孔隙结构特征和分形规律特性。结果表明:随着煤级的增高,煤的BET比表面积先增加后减小,BJH孔体积逐渐减小,孔径分布特征为微孔先减少后增多,小孔和中孔先增多后减少;FHH分形维数D1值可量化表征煤体表面的粗糙程度,随着煤级的增高而增加,其中气肥煤至贫煤阶段变化较小,无烟煤阶段增加较多,范围为2.2562~2.4613;分形维数D2值可量化表征煤的孔隙结构的复杂性,D2值先减小后增大,范围为2.4591~2.8065。

In order to study the evolution characteristics of the pore structure of medium and high rank coals,the low-temperature nitrogen adsorption method and the FHH fractal theory model were used to explore the regularity of pore structure characteristics and fractal characteristics of different rank coals.The results show that as the coal rank increases,the BET specific surface area of the coal increases first and then decreases,the BJH pore volume gradually decreases.As for the coal pore size distribution,the number of micro-pores decreases first and then increases,and the number of small and mesopores increases first and then decreases;the value of the FHH fractal dimension D1 can quantify the roughness of the coal surface,which increases with the increase of coal rank.The change of D1 value of the gas-fat coal and lean coal is small,and anthracite stage increases more,the range is 2.2562 to 2.4613;the D2 value can quantify the complexity of the pore structure of coal.The D2 value decreases first and then increases with the increase of coal rank,ranging from 2.4591 to 2.8065.