科研之友
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摘要
Methane adsorption capacity of coal is one of the major factors influencing total gas-in-place and it is linked to coal structure, while our knowledge of it is still limited. In this study, coal structures were classified into five categories, including integrated, blocky, cataclastic, granulated and mylonitized. The integrated and blocky coals are intact and the other three are deformed. To investigate the methane adsorption capacity, adsorption potential and surface free energy of different structure coals, four high rank coal samples were collected from No.3 coal seam of the Zhaozhuang coal mine in Southeastern Qinshui Basin China, and a series of methane isothermal adsorption experiments and pore distribution measurements were carried out in the laboratory, and then the adsorption potential and the surface free energy were analyzed. It turns out that, there are no obvious differences in the methane adsorption capacity for the various structure coals when the equilibrium pressure is below 2 MPa; while there are significant differences when the pressure is above 2 MPa. The higher the gas pressure is, the greater the difference is. Methane adsorption capacity of different structure coals can be arranged in a descending order: mylonitized > granulated > cataclastic > intact. That is, the methane adsorption capacity is higher for the deformed coal samples than for the intact ones. Both the specific surface area and the pore volume increase with the increase of deformation degree. Mesopores contribute most to the total pore volume; while the adsorption pores have the greatest contribution to the total specific surface area. The adsorption potential and surface free energy for different-structure coals under the same adsorption space volume increase with the increase of deformation degree. Adsorption potential decreases with the increase of adsorption space, and the adsorption potential of micropore is considerably higher than that of mesopore and macropore. As the temperature rises, the cumulative reduction of surface free energy decreases and the surface free energy decreases significantly at each equilibrium pressure. Methane adsorption in coal is dominated by adsorption potential and surface free energy.
- 出版日期2016-10
- 单位中国地质大学（北京）; 中国矿业大学（北京）; 三峡大学
