软硬煤瓦斯解吸规律及影响因素的实验研究

Experimental study on gas desorption laws and influence factors of soft and hard coal

为了研究软硬煤瓦斯解吸规律,搭建了大质量瓦斯解吸实验系统,进行了不同变质程度软硬煤的瓦斯解吸实验,对比分析了软硬煤的孔隙结构特征,查明了软硬煤的瓦斯解吸规律及影响因素。研究结果表明:软煤相对于硬煤,具有更多的瓦斯解吸总量和更快的解吸速度,采用幂函数可以较好的描述软硬煤的解吸规律,煤的破坏类型和变质程度是影响瓦斯解吸量的主要因素;软硬煤瓦斯解吸规律的差异性主要受煤的孔隙结构影响,软煤总孔容是硬煤的1.18~2.14倍,且软煤中孔及大孔更为发育,这为瓦斯解吸提供了更优质的通道;软煤相对硬煤在同等条件下变质程度更高,煤吸附甲烷的能力更强,这有利于软煤瓦斯解吸量的增加及解吸速度的加快。研究成果为准确测试煤层瓦斯含量和钻屑解吸指标提供了理论依据。

In order to study the gas desorption laws of soft and hard coal,a large mass gas desorption experimental system was developed. The gas desorption experiments of soft and hard coal with different metamorphic degree were carried out,and the gas desorption laws and influence factors of soft and hard coal were found out through comparative analysis on the pore structure characteristics of soft and hard coal. The results showed that the soft coal has larger total gas desorption amount and faster desorption speed compared with hard coal. The power function can be used to describe the desorption laws of soft and hard coal better,and the damage type and metamorphic degree of cola are the main influence factors of gas desorption amount. The difference of gas desorption between soft and hard coal is mainly controlled by the pore structure of coal,the total pore volume of soft coal is 1. 18-2. 14 times of hard coal,and the middle pore and larger pore of soft coal are more developed,which provide a more excellent channel for gas desorption. Compared with the hard coal under the same conditions,the metamorphic degree of soft coal is higher,and the gas adsorption capacity is stronger,which is beneficial to increase the gas desorption amount and accelerate the desorption speed of soft coal. The results provide the theoretical basis for accurately measuring the gas content in coal seam and the desorption index of drill cuttings.