Gao Tao, Han Qing, Deng Cunbao, Zhang Hao
College of Safety and Emergency Management and Engineering, Taiyuan University of Technology, Jinzhong 030600, China.
ACS Omega. 2023 Mar 8;8(11):10618-10628. doi: 10.1021/acsomega.3c00716. eCollection 2023 Mar 21.
A kind of closed mining and nonventilation working face is proposed, which provides a possibility for eliminating coal mine accidents and extracting high-purity gas. During mining, a confined space above normal pressure is formed in the face. Geological conditions cause significant differences in the physicochemical properties of coal and affect the occurrence and migration of gas in coal seams. The pore structures of five coal samples were obtained by mercury injection and low-temperature nitrogen adsorption. The self-made positive pressure desorption experimental device was used to conduct isothermal desorption experiments under different environmental pressures. An extended Langmuir model was proposed to carry out regression analysis on the curve of positive pressure desorption with time. The effect of coal pore structure on gas diffusion properties was discussed. The results indicate that the development degree of micropores in coal determines the amount of gas adsorption. With the increase of coal rank, both the ultimate desorption quantity and desorption rate first decrease and then increase. The positive pressure enhances the concentration of methane outside the coal and inhibits methane diffusion. With an increase of positive pressure, the desorption capacity of the high-rank ZG was significantly inhibited, and the desorption limit and initial desorption rate decreased by 15.80-44.54 and 16.92-47.93%, respectively. The diffusion coefficient of the middle-rank XS has the greatest decrease rate of 1.56-18.05%. The pore structure of coal is the essential reason that affects methane diffusion.
提出了一种封闭开采且无通风的工作面，这为消除煤矿事故及提取高纯度瓦斯提供了可能。开采过程中，工作面内形成常压以上的受限空间。地质条件导致煤的物理化学性质存在显著差异，影响煤层瓦斯的赋存与运移。通过压汞法和低温氮吸附法获得了5个煤样的孔隙结构。利用自制的正压解吸实验装置在不同环境压力下进行等温解吸实验。提出扩展朗缪尔模型对正压解吸随时间的曲线进行回归分析。探讨了煤孔隙结构对瓦斯扩散特性的影响。结果表明，煤中微孔的发育程度决定了瓦斯吸附量。随着煤阶的升高，极限解吸量和解吸速率均先降低后升高。正压提高了煤体外甲烷的浓度，抑制了甲烷扩散。随着正压的增加，高阶煤ZG的解吸能力受到显著抑制，解吸极限和初始解吸速率分别降低了15.80 - 44.54%和16.92 - 47.93%。中阶煤XS的扩散系数下降速率最大，为1.56 - 18.05%。煤的孔隙结构是影响甲烷扩散的根本原因。
