Study on Adsorption Characteristics of Deep Coking Coal Based on Molecular Simulation and Experiments

To study the effect of high temperature and high pressure on the adsorption characteristics of coking coal, Liulin coking coal and Pingdingshan coking coal were selected as the research objects, and isotherm adsorption curves at different temperatures and pressures were obtained by combining isotherm adsorption experiments and molecular dynamics methods. The effect of high temperature and high pressure on the adsorption characteristics of coking coal was analyzed, and an isothermal adsorption model suitable for high-temperature and high-pressure conditions was studied. The results show that the adsorption characteristics of deep coking coal can be well characterized by the molecular dynamics method. Under a supercritical condition, the excess adsorption capacity of methane decreases with the increase of temperature. With the increase of pressure, the excess adsorption capacity rapidly increases in the early stage, temporarily stabilizes in the middle stage, and decreases in the later stage. Based on the classical adsorption model, the adsorption capacity of coking coal under high-temperature and high-pressure environments is fitted. The fitting degree ranges from good to poor. The order is D-R > D-A > L-F >BET > Langmuir, and combined with temperature gradient, pressure gradient, and the D-R adsorption model, it can be seen that after 800 m deep in Liulin Mine and 400 m deep in Pingdingshan Mine, the adsorption capacity of coking coal to methane decreases with the increase of depth.