Simulation of the desorption process of methane adsorbed in a coal rock, taking into account intermolecular sorption interactions in the system “methane-coal”

Abstract

Based on the analysis of the stages of the desorption of methane adsorbed in the coal rock, the simulation of this process was based on its consideration as an activation process of diffusion. It was found that the intermolecular sorption interactions in the “methane-coal” system should be described by the Lennard-Jones potential, taking into account the polymeric nature of the molecular structure of coal. Therefore, an analysis of the modern theories of the kinetics of nonequilibrium sorption processes in high-molecular materials was performed. This analysis showed that the complex of the main molecular factors in the system “methane – coal” can be taken into account most correctly using the Pace – Deutiner molecular parameters. The diffusion coefficient in the equation takes into account the activation energy of the diffusion process, intermolecular sorption interactions in the “methane-coal” system, the parameters of the microstructure of coal, the physical properties of methane and the magnitude of its diffusion jump. The analytical calculation of the diffusion equation is carried out. It allows determining the patterns of the desorption process in various geological conditions of mining operations.