Study on the method of testing the adsorption and diffusion capacities of coal matrix and its influencing factors using the sliced coal samples

Abstract

ABSTRACT Through the reasonable design of experimental instrument, the experimental mechanism of adsorption-diffusion of thin sliced coal samples is explored, and a set of rigorous experimental procedures, data acquisition, and processing methods are formed. The method is to grind coal samples into rectangular samples with thickness less than 4 mm and place them in a sealed container. The adsorption and diffusion characteristics of the coal matrix are accurately reflected due to its original internal structure. The three-dimensional diffusion model of the Fick’s second law is simplified to one-dimensional diffusion model, and the diffusion coefficient is calculated. The accuracy of experimental parameters is improved by the instrument combination of sample diffusion test cylinder, pressure reference cylinder and differential pressure gauge. Meanwhile, a set of calculation methods for the adsorption amount and diffusion coefficient of coal slice is proposed. The experimental results indicate that the diffusion coefficient of coal matrix is sensitive to temperature and diffusion path, but insensitive to pressure and fixed carbon content of coal matrix. The adsorption amount is sensitive to the change of fixed carbon content. Meanwhile, the experimental results of different coal samples are basically consistent with the characteristics of the production wells in the mine.