含瓦斯煤低温取芯过程煤芯温度变化规律实验研究

Experimental study on change laws of coal core temperature during low temperature coring process of coal containing gas

为避免现有的煤层瓦斯含量井下测定方法在取样过程中出现瓦斯损失量较多的情况,提出了低温(0℃及以下)取芯的方法。煤芯温度是影响取芯过程瓦斯损失量的主要因素,使用自制模拟装置,对含瓦斯煤低温环境取芯过程温度变化规律进行了实验研究。研究结果表明:在定量冷冻剂的条件下,保持初始吸附平衡压力不变,随着外加热源热量输出强度的增加,煤芯在低温环境(0℃及以下)持续时间和升温时间均减小,降到所需低温环境的速度很快,均在8 min以内;保持外加热源热量输出强度不变,改变初始吸附平衡压力,煤芯温度降至所需低温环境时间在8 min以内,且低温环境持续时间都能稳定在130 min以上。在实验过程中,煤芯温度呈"U"形变化,经历快速下降、低温维持、温度回升3个阶段。

In view of the situation that there is more gas loss during the sampling process when using the existing underground measurement methods of gas content in the coal seam, a method of low temperature coring （0℃ and below） was proposed. The coal core temperature is the main factor affecting the gas loss during the coring process, and the experimental study was carried out on the change laws of temperature during the coring process of coal containing gas in the low temperature environ- ment by using the self-made simulation device. The results showed that when the quantity of refrigerant was fixed and keeping the initial adsorption equilibrium pressure unchanged, both the duration of low- temperature environment and the temperature rise time of coal core decreased with the increase of heat output intensity of the external heat source, and the speeds of decreasing to the required low temperature environment were very fast, all within 8 minutes. When keeping the heat output intensity of the external heat source unchanged and the initial adsorption equilibrium pressure changed, the time of coal core temperature decreasing to the required low temperature environment were within 8 minutes, and the duration of low- temperature environment were stable for more than 130 minutes. The coal core temperature presented a ＂U＂ shape change during the experiment process, and experienced three stages including rapid decrease, low temperature maintenance and temperature recovery.