瓦斯含量测定中取心管管壁温度变化特性研究

Study on characteristics of temperature variation of coring tube wall during gas content determination process

为确定煤矿冷冻取心过程所需合理冷冻剂量,对取心管取心过程管壁温度变化特性研究是解决此问题的关键。使用自主研发的取心管自动测温装置,分别进行了取心深度为5、20、40 m下取心管管壁温度测试(下管阶段、切削阶段和退钻阶段)。通过建立取心管管壁传热模型,基于顺序函数法求解二维非稳态导热反问题,验证并分析了取心过程管壁温度变化规律。研究结果表明:在下管阶段,取心深度较大(40 m)时,存在取心管快速升温的现象;在切削阶段,不同取心深度下,取心管温度均在切削进行一段时间后开始迅速升高,切削结束时升至最高值;在退钻阶段,取心管温降速度基本相同,处于一个缓慢降温的状态;利用顺序函数法求解重构的取心管管壁模拟温度与现场实测温度吻合良好,误差小。研究结果可为煤层瓦斯含量测定低温冷冻取心装置的开发提供参考。

In order to determine the reasonable dosage of freezing required in the process of coal mine freezing and coring,the key to solve the problem is to study the temperature characteristics of the tube wall during the coring process.Based on the self-developed automatic temperature measuring device for coring tube,the coring tube wall temperature test was carried out at the coring depth of 5,20 and 40 m(lower tube stage,cutting stage,and retraction stage).By establishing the heat transfer model of the tube wall of the coring tube,the inverse problem of two-dimensional unsteady heat conduction was solved based on the sequential function method,and the temperature change law of the tube wall during the coring process was verified and analyzed.The results showed that in the tube lowering stage,when the coring depth was larger(40 m),the temperature of coring tube rose rapidly.In the cutting stage,at different coring depths,the temperature of the coring tube began to rise rapidly after a period of cutting,and reached the highest value at the end of the cutting.In the withdrawal stage,the temperature drop rate of coring tube was basically the same,and it was in a slow cooling state.The simulated temperature of the reconstructed core tube wall by using sequential function specification method was in good agreement with the field measured temperature,and the error was small.The research results can provide a reference for the development of low-temperature freezing and coring device for the determination of coal seam gas content.