A Langmuir-like desorption model for reflecting the inhomogeneous pore structure of coal and its experimental verification

Abstract

A Langmuir-like model was established to describe the desorption kinetics of methane in coal with inhomogeneous pore structure. Two Chinese coal samples were selected to study the initial CH₄ desorption rate in coals with the volumetric method under five equilibrium pressures. The results show that the pressure has a significant influence on desorption kinetics of methane in coal. At a constant temperature, the desorption volume increases with pressure. And at a given desorption time, the desorption volume appears to have a Langmuir-like relationship with pressure. Also, the relationship between the parameters in the Langmuir-like model and desorption time is a power function. Thus, we can obtain the changing law of desorption volume with the equilibrium pressure and the desorption time from a Langmuir-like model. This model is a valuable option to the prediction of lost gas content and identification of coal and gas outburst.