Abstract:
In order to reveal the characteristics and control mechanism of supercritical CO
2 (ScCO
2) adsorption in deep-seated coal seams, coal No.3 from Yuwu coal mine, Sihe coal mine and Chengzhuang coal mine was chosen as the research object, the isothermal adsorption experiments in different temperature(45℃, 62.5℃, 80℃)were conducted with the maximum pressure above the supercritical pressure of CO
2 by means of homemade isothermal adsorption instrument. The results show that the adsorption isotherm of ScCO
2 under the condition of high temperature and high pressure is different from the adsorption isotherm of CO
2 under normal temperature and pressure. The excess adsorption capacity of ScCO
2 had the variation of 4 sections, the absolute adsorption capacity of ScCO
2 had the variation of 3 sections. The pressure points matched with the maximum on excess adsorption capacity of ScCO
2 had the characteristics of drifting high pressure with increase of the formation temperature. The excess adsorption capacity of ScCO
2 was far below the absolute adsorption capacity of ScCO
2, they couldn't be explained ith the adsorption model of Langmuir. The temperature has an obvious inhibition to the adsorption of ScCO
2, the moisture content has no inhibition to the adsorption of ScCO
2, the high ash content has an obvious inhibition to the adsorption of ScCO
2, the high vitrinite and R
max have a relatively obvious promotion to the adsorption of ScCO
2. The adsorption capacity of ScCO
2 is controlled by micropore and transitional pore, is especially related to the amount of specific surface area from micropore, the decrease on the adsorption ability of ScCO
2 from high metamorphic coal may be caused by filling of the minerals in coal.