Experimental study on adsorption promotion and desorption restrain of gas-containing coal in low-temperature environment

Aiming at the problem that the coal seam temperature is high and the gas desorption rate is fast, the gas content loss is estimated to be biased, resulting in inaccurate measurement of coal seam gas content. This paper proposes a method for taking the coal samples at low temperature (below 0 °C) in order to improve the accuracy of gas content measurement by suppressing the release of gas. Based on the importance of gas adsorption desorption in the prediction of gas diffusion law in coal, this paper analyzes the gas adsorption/desorption characteristics of standard size raw coal in low-temperature environment with self-designed low-temperature environment gas adsorption/desorption test platform. Experimental study has been conducted on the gas adsorption promotion and desorption restrain of environmental coal. The results show that (1) the temperature increase promotes the adsorption of coal to gas. The lower the temperature is, the more obvious the adsorption effect will be; and the lower the temperature inhibits the gas desorption; likewise the lower the temperature is, the more obvious the restrain of desorption will be. (2) The gas desorption rate of coal can be divided into three significant stages. Among them, stage I has the shortest time, the desorption rate is the largest, and the gas desorption amount is the most; stage III is the longest, the gas desorption rate is the second, and the gas desorption amount is the middle; stage II desorption rate is the smallest, and the desorption amount is the least. (3) Lowering the temperature has different effects on the gas desorption rate of coal in three stages. The gas desorption rate of the coal in the first stage is mainly suppressed, and the gas desorption rate data has a quadratic function increasing with the increase of the adsorption equilibrium temperature. However, the gas desorption in the second and third stages of coal is a promoting effect, and the gas desorption rate data decreases with the increase of the adsorption equilibrium temperature. (4) The research on the gas desorption restrain effect of low temperature environment coal will provide theoretical basis for the development and application of underground cryo-coring technology.