Temperature and deformation changes in anthracite coal after methane adsorption

Abstract

Micropores are the primary sites of methane adsorption in coal, and the heterogeneous mesostructures of coal create the non-uniform distribution of the micropores in coal. Using a thermal infrared imager, the temperature distribution on the surface of an anthracite sample during methane adsorption/desorption was tested in this paper, and a new method is advanced to calculate methane adsorption capacity in coal based on its temperature increment. The results confirm the strongly non-uniform distribution of methane adsorption in coal. A X-ray CT scan test demonstrates that the volumetric zones of coal sample with a strong methane adsorption capacity have a lower average density. In these regions, the clay minerals with developed micropores also have a strong methane adsorption capacity. During the coal skeleton deformation of methane adsorption, the high density is hard to be squeezed, while low density areas are likely to be squeezed. Therefore, the complexity density distribution in coal leads to the incompatibility of deformation, which make the direct determination of regional uptake a challenge; From the SEM micrographs of the same coal sample with different densities determined by the X-ray CT scan, the mesostructures of cell cavity pores with non-compact packing of the clay minerals appear to be the primary sites of methane adsorption in coal, and the telocollinite with fewer pores has a lower methane adsorption capacity.