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雷红艳. 真空充He法测定吸附罐剩余体积试验研究[J]. 煤炭科学技术,2024,52(S1):1−8. doi: 10.12438/cst.2024-0517
引用本文: 雷红艳. 真空充He法测定吸附罐剩余体积试验研究[J]. 煤炭科学技术,2024,52(S1):1−8. doi: 10.12438/cst.2024-0517
LEI Hongyan. Experimental study on determination of residual space volume of adsorption tank by vacuum filled He method[J]. Coal Science and Technology,2024,52(S1):1−8. doi: 10.12438/cst.2024-0517
Citation: LEI Hongyan. Experimental study on determination of residual space volume of adsorption tank by vacuum filled He method[J]. Coal Science and Technology,2024,52(S1):1−8. doi: 10.12438/cst.2024-0517

真空充He法测定吸附罐剩余体积试验研究

Experimental study on determination of residual space volume of adsorption tank by vacuum filled He method

  • 摘要: 为研究真空充He法测定吸附罐剩余体积对瓦斯吸附量的影响,以10个煤样为研究对象,采用容量法在低压及高压下进行真空充He测定、瓦斯吸附常数测定、真密度测定等试验。研究表明:① 高压下煤几乎不吸附He,负压状态下由于He分子动力学直径小于CH4分子动力学直径,容易持续不断地被负压差吸入更小的纳米级煤孔隙内,导致剩余体积随着充入He时间延长而不断增大,形成一种煤吸附He的假象。② 相对于真密度计算法,真空充He法在5、30、60、90、120 min读数时的吸附罐剩余体积基本偏大,5 min读数时绝对值误差最大为9.58%,最小为1.52%;采用真空充He法读数时间可设定为5 min,与吸附罐空罐体积读数时间相同。③ 采用真空充He法计算的瓦斯吸附常数a值一般偏小,b值一般偏大。5 min读数时a值绝对值误差最大为17.69%,最小为4.24%,b值绝对值误差最大为33.59%,最小为7.51%,远大于低压瓦斯吸附量误差0.45%~5.64%。真空充He法对0.1 MPa压力下瓦斯吸附量影响较小,对高压吸附量影响较大,剩余体积误差是煤样出现“负吸附”的根本原因,吸附罐剩余体积是影响煤的气体吸附量的主控因素。④ 通过试验得出煤吸附不同气体采用真空充He法“一刀切”测定剩余体积不科学,理论上应采用与被测气体分子动力学直径相等的惰性气体标定,而实际上很难选择到与被测气体分子直径相等的惰性气体。⑤ 建立剩余体积偏差量与瓦斯吸附常数偏差量的修正模型,通过此模型可对采用真空充He法测定的ab值进行修正,提高ab值的准确性和可靠性,对矿井瓦斯灾害精准防治及煤层注CO2驱替CH4等科学研究提供参考与指导。

     

    Abstract: In order to study the effect of measuring the residual volume of adsorption tank with vacuum filling He method on the gas adsorption capacity, 10 coal samples were taken as research objects, and experiments such as vacuum filling He measurement, gas adsorption constant measurement and true density measurement were carried out with capacity method under low pressure and high pressure. The research shows that: ① coal hardly adsorbed He under high pressure; under negative pressure, He molecular dynamics diameter is smaller than CH4 molecular dynamics diameter, and it is easy to be continuously sucked into smaller nanoscale coal pores by negative pressure difference, resulting in the remaining volume increasing with the extension of He filling time, forming an illusion of coal adsorbed He. ② Compared with the true densitometer algorithm, the residual volume of the adsorption tank of the vacuum filling He method is basically larger at 5, 30, 60, 90 and 120 min reading, and the absolute error at 5 min reading is 9.58% at the maximum and 1.52% at the minimum; The reading time of vacuum filling He method can be set to 5 min, which is the same as the reading time of the empty tank volume of the adsorption tank. ③ The value a of the gas adsorption constant calculated by the vacuum He method is generally small, and the value b is generally large. In the 5 min reading, the absolute error of a value is the maximum 17.69% and the minimum 4.24%, and the absolute error of b value is the maximum 33.59% and the minimum 7.51%, which is much larger than the error of low pressure gas adsorption capacity 0.45%~5.64%. Vacuum He filling method has little influence on gas adsorption capacity under 0.1 MPa pressure, but has a greater influence on the adsorption capacity at high pressure. The residual volume error is the root cause of “negative adsorption” of coal sample, and the residual volume of adsorption tank is the main factor affecting the gas adsorption capacity of coal. ④ The experiment shows that it is not scientific to use vacuum filling He method to determine the residual volume of different gases adsorbed by coal. In theory, the inert gas with the same molecular kinetic diameter as the measured gas should be used for calibration, but in practice it is difficult to select the inert gas with the same molecular diameter as the measured gas. ⑤ Establish a correction model of residual volume deviation and gas adsorption constant deviation, through which the a and b values determined by vacuum filling He method can be corrected, improve the accuracy and reliability of A and b values, and provide guidance and reference for the accurate prevention and control of mine gas disasters and the scientific research of coal seam CO2 injection for CH4 displacement.

     

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