高压注入和等压扩散条件下N2置换煤中CH4的研究

为探究注气置换抽采煤层瓦斯的效果,揭示注弱吸附性气体N2在等压扩散和高压注入2种条件下置换煤中CH4的机理,采用自行搭建的含瓦斯煤多元气体置换试验装置,开展等压扩散和高压注入2种条件下注N2置换煤中CH4的试验研究.研究结果表明:在注N2量相同的条件下,等压扩散置换量始终高于高压注气置换量,在等压扩散下N2置换CH4效...

Study on replacement methane with nitrogen from coal by high pressure injection and equal pressure diffusion

To explore the effect of coal seam gas drainage by gas injection replacement,and reveal the mechanism of replacement of CH4 in coal by the injection of weak adsorption gas N2 under the two conditions of equal pressure diffusion and high pressure injection,a self-built test device of multi-element gas replacement for coal containing gas was used to carry out the experimental research on the replacement of CH4 in coal by N2 injection under the two conditions of equal pressure diffusion and high pressure injection.The results showed that the replacement amount of equal pressure diffusion was always higher than that of high pressure gas injection under the same amount of N2 injection.The efficiency of N2 replacement CH4 fluctuated at 21.32% under equal pressure diffusion,and the replacement efficiency under high pressure injection decreased with the increase of N2 injection amount.The CH4 in coal could be replaced by N2 injection under equal pressure diffusion was mainly because of the decrease of partial pressure of CH4 and competitive adsorption of gas.The CH4 in coal could be replaced by high pressure N2 injection was mainly because of the total pressure rise in the free phase and the competitive adsorption of gas.Under the same amount of N2 injection,both the CH4 desorption rate and N2 injection-replacement ratio under equal pressure diffusion were higher than those under high pressure injection,and the replacement effect of CH4 in coal by N2 injection with the equal pressure diffusion method was better.