Experimental study on kinetic characteristics of gas adsorption of coal with different degrees of metamorphism

In order to further reveal the dynamic characteristics of coal with different degrees of metamorphism under different adsorption pressures, the self-developed TQY-2 precision adsorption instrument and infrared thermal imaging device were used to conduct macroscopic adsorption tests on lignite, coking coal and anthracite coal samples with a diameter of 8.5 mm at different pressures (0.2, 0.4, 0.6, 0.8, 1.0 MPa) and the adsorption test of the mesoscopic structure of the coal body with adsorption pressures of (0.3, 0.6, 0.9, 1.2, 1.5 MPa), using quasi-primary and quasi-secondary adsorption kinetic models such as intra-particle diffusion, Elovich and double constant analyze the law and mechanism of adsorption gas. The results show that compared with five adsorption kinetics models, the quasi-secondary adsorption kinetics model is suitable for characterizing the adsorption gas process of lignite and coking coal, while the optimal model for anthracite is the intra-particle diffusion model; with the increase of adsorption pressure, the quasi-secondary adsorption rate constant k2 of lignite and coking coal gradually increased, and the intra-particle diffusion rate constant kp of anthracite coal also gradually increased, all of which were positively correlated; adsorption pressure has little effect on the dynamic model suitable for coal samples; under the macroscopic adsorption experiment and the mesoscopic structure adsorption experiment of coal body based on infrared thermography, the dynamic models suitable for different degrees of metamorphism are consistent.