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利用自行设计的自约束渗透装置,采用热导检测器在线跟踪穿透实验过程中CO2或He的渗透信号,在40℃条件下,对比研究了CO2和He在阳泉煤CH4饱和基质煤柱(φ6×13mm)中的渗透行为,讨论了煤对气体的吸附或吸取作用及孔隙气压对渗透率的影响。研究表明,有别于煤对He的作用,在CO2和CH4交替渗透时,不同的CH4吹扫时间,对应于不同的CO2初始穿透时间。CO2穿透后被CH4吹扫36h,在煤柱中仍有残留,表明煤对CO2具有相对较强的吸着作用。He在煤柱中穿透后没有明显残留,并且He在测试煤柱中渗透率明显大于CO2的渗透率。在测试条件下,气体交替渗透多次的稳定渗透率无明显变化,表明煤柱的结构没有发生显著变化。由于孔壁效应、煤基质膨胀、吸附边界层等因素的存在,使得气体渗透率随孔隙气体压力的增加而降低。
The self-designed self-confining infiltration device was used to track the permeation signal of CO2 or He during the experiment through the thermal conductivity detector. The effect of CO2 and He on the saturated matrix coal column of Yangquan coal (φ6 × 13mm). The effects of adsorption or absorption of coal on gas and the influence of pore pressure on permeability were discussed. Studies have shown that different from the effect of coal on He, different CH4 purge times correspond to different initial CO2 breakthrough times when CO2 and CH4 are alternately infiltrated. After the CO2 breakthrough, it was purged by CH4 for 36h and remained in the coal column, indicating that coal has a relatively strong sorption effect on CO2. He has no significant residue after it penetrates in the pillars, and He has significantly greater permeability in the test pillars than CO2. Under the test conditions, there is no obvious change in the steady permeability of the gas alternately infiltrated many times, indicating that the structure of the coal pillar has not changed significantly. Due to pore wall effect, coal matrix expansion, adsorption boundary layer and other factors, the gas permeability decreases with the increase of pore gas pressure.