缓速酸对无烟煤中瓦斯放散初速度的影响研究

Study on the Effect of Retarded Acid on the Initial Velocity of Gas Emission in Anthracite

缓速酸对降低煤岩反应速率、提高煤层气采收率意义重大。以贵州某矿的无烟煤为研究对象,开展静态溶蚀、瓦斯放散初速度、低温CO_(2)吸附及红外光谱试验,分别从物理、化学角度分析试验煤样的孔隙结构和含氧官能团数量对煤中瓦斯放散初速度的影响机制。研究结果表明:乙酸质量浓度为5%时,酸化缓速效果最佳,缓速率为41.03%;与原煤样相比,氢氟酸酸化煤的瓦斯放散初速度增大,一方面氢氟酸改善了试验煤样的孔隙连通性,增加了过渡孔和大孔数量,减小了煤样的比表面积,另一方面,氢氟酸处理后试验煤样的含氧官能团数量增加,抑制了煤对瓦斯的吸附;对比原煤样,缓速酸酸化煤的瓦斯放散初速度减小,这是因为缓速酸作用增加了试验煤样的微孔数量,增大了煤样的比表面积,减小了煤样的含氧官能团数量,使其表面结构更加复杂,促进了煤对瓦斯的吸附。研究成果为贵州某矿区煤层气酸化增产技术奠定了理论基础。

Retarded acid is of great significance to reduce the reaction rate of coal and improve the recovery rate of coalbed methane.Taking the anthracite of a mine in Guizhou as the research object,tests on static dissolution,initial velocity of gas emission,low-temperature CO_(2)adsorption and infrared spectroscopy were carried out.The influence mechanisms of pore structure and number of oxygen-containing functional groups of coal samples on the initial velocity of gas emission in coal were analyzed from physical and chemical perspectives.The results show that the acidification retarding effect is the best when the mass concentration of acetic acid is 5%,and the retarding rate is 41.03%.Compared with the original coal sample,the initial velocity of gas emission of hydrofluoric acid acidified coal increases.On one hand,hydrofluoric acid improves the pore connectivity of the coal samples,increases the number of transition pores and large pores,and reduces the specific surface area of the coal samples.On the other hand,the number of oxygen-containing functional groups in the coal samples increases after hydrofluoric acid treatment,which inhibits the adsorption of gas by coal.Compared with the original coal samples,the initial velocity of gas emission of retarded acid acidified coal decreases.This is because the action of retarded acid increases the number of micropores of the coal samples,increases the specific surface area of the coal samples,and reduces the number of oxygen-containing functional groups of the coal samples.Therefore,the surface structure is more complex,which promotes the adsorption of coal to gas.The research results have laid a theoretical foundation for the acidizing stimulation technology of coalbed methane in this mining area of Guizhou.