Adsorption characteristics of lignite in China

Abstract

To help in ascertaining methane content of lignite reservoir in China, the isothermal adsorption measurements of methane have been performed on moisture-equilibrated coals of some typical lignite-bearing basins, which comprise maximum reflectance of vitrinite (R _{o, max}) ranging from 0.24% to 0.50%. Related to other coal properties, our analysis shows that methane adsorption of lignite is mainly affected by coalification, as well as by maceral composition, moisture content, and seam temperature. Maximum methane capacities of moisture-equilibrated lignite coals show a continuously increasing (and reasonably exponential) trend with increasing R _{o, max}. Methane adsorption capacity decreases with maceral composition besides the range 40%–60%, respectively. Moisture content shows discretely correspondence with methane capacity. Methane capacity also decreases as seam temperature increases, and its reduction increases with pressure under a certain temperature.

Keywords

lignite / methane adsorption / characteristics / influencing factor

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