Effect of heat adsorption of gas desorption on the measurement of gas pressure and optimization of coal sample canister

Aiming at the abnormal case that gas desorption pressure increased first then decreased during underground measurement in Zhaozhuang coal mine in Jingcheng, through analysis and investigation of the possible problems of instruments and site environments, it was determined that the gas temperature reduction in the canister was induced by heat adsorption during gas desorption, thus resulting in the abnormal results of desorption pressure measurement. In order to solve this problem, good heat-conducting material was used to design and manufacture coal sample canister so as to achieve thermal balance inside and outside the canister. The desorption pressure of coal sample canister in air and water was studied. The study found that the desorption pressure in a canister in air increased first and then decreased, but the desorption pressure in a canister in water got back rapidly. According to the principle of water bath of gas desorption device of constant temperature in lab, the coal sample canisters with double walls filled with water were designed and manufactured, the adsorbed heat, the specific heat capacity and the water demand of methane were studied and analyzed quantitatively. In lab, the gas desorption law of coal samples of Zhaozhuang mine was measured and analyzed, verifying that the coal sample canister could meet the requirement of industrial application.