Adsorptive Capacity of Coals and Its Affecting Factors

In order to research on the gas storage capacity of coal, a series of tests were carried out using 124 coal samples. These tests include: isothermal adsorption test, coal petrography analysis, proximate analysis, mercury intrusion test and cryogenic liquid nitrogen test. The research shows: (1) Coal metamorphism controls the adsorptive capacity. As R _max increases from 0.3% to 4.25%, the volume of Langmuir increases from 11.25 to 47.16 cm³/g. (2) The capacity rate of the coal processed with equilibrium moisture has a normal correlation to the vitrinite content and an inverse correlation to the inertinite content of the coal, and displays a normal correlation to the specific surface areas of pore and micropore, and micropore volume. (3) The moisture and temperature have inverse influence on coal adsorptive capacity. Coals at different metamorphic stages have different variation tendency of adsorption curves. The adsorptive capacity of gas coal increases with temperature and pressure, indicating the dominant role of pressure. The adsorptive capacity of anthracite increases with increasing temperature and pressure when the temperature is lower than 60 ℃ and the pressure lower than 15 MPa, which also indicates the dominant role of pressure. When the temperature is over 60 ℃ and the pressure higher than 15 MPa, the adsorptive capacity of the anthracite decreases, suggesting that the influence of temperature is stronger than that of pressure.