Experimental study on swelling characteristics of CO2 adsorption and storage in different coal rank

HE Wei; LIANG Weiguo; ZHANG Beining; LI Ziwen; LI Li

doi:10.13225/j.cnki.jccs.2017.1138

Abstract：Based on the gas isothermal adsorption device developed by ourselves and the TST3 827 dynamic and static strain test system,the isothermal adsorption test of CO2 was carried out under different adsorption pressure conditions at constant temperature (50 ℃) for four different coal samples to study the adsorption capacity of different coal rank samples in CO2 and the swelling caused by adsorption.The results show that the adsorption capacity of CO2 is closely related to the coal rank.Under the same adsorption pressure,the adsorption capacity of CO2 increases with the increase of coal rank.The isothermal adsorption curves of different coal rank samples are similar,and the excess adsorption capacity of coal samples increases first and then decreases with the adsorption pressure,and reaches the maximum at about 8 MPa.The deformation of the different rank coal due to adsorption in CO2 also has a similar trend,that is,with the increase of CO2 pressure,the volume strain increases first and then tends to be stable,and the volume strain can be described by DR model introducing CO2 density,and with the increase of coal rank,the volume strain gradually decreases.Due to the structural characteristics of the coal,the strain in the direction perpendicular to the bedding is about 1.8-2.3 times that of the parallel strain in the bedding direction.The volume strain and the absolute adsorption capacity of the coal are linearly increasing in the gaseous CO2,and when the CO2 reaches the supercritical state,the volume strain tends to be stable with the absolute adsorption capacity,and the volumetric strain of coal with the same adsorption amount of CO2 is reduced with the increase of coal rank.