Study On Gas Adsorption Of Anthracite Using A Low-field NMR Relaxation Method

In this article,Henan Jiaozuo Zhaogu and Shanxi Jincheng Wangtaipu Coalmine anthracite were used as the research object.The influence of different low-field NMR;and moisture contents on anthracite gas adsorption was studied with low-field NMR technique.The NMR spectra of gas adsorption in coal samples under different gas pressures and moisture contents were obtained.The relationships between T₂ spectra nuclear magnetic signal and anthracite gas adsorption results was established with the low-field NMR technique experiment.The research shows that:With the increase of adsorption time,the total gas adsorption of anthracite coal samples at different gas pressure points increases and then stabilizes.When adsorption time increases,the amount of gas adsorbed in the micropores of Jiaozuo anthracite increases and then stabilizes in the saturated anthracite samples.As for Jincheng saturated anthracite samples,water and gas in the the mesopores and macropores are moved into micropores under the action of gas pressure.The greater the gas pressure point,the faster the moisture and gas move from the mesopores and macropores to the micropores.When the gas pressure increases,the time of adsorption equilibrium increases.At the beginning of the increase of gas pressure,the increase of the amount of gas adsorbed by coal sample is larger and then gradually decreases.When the gas pressure increases,the increase of gas adsorption capacity of saturated anthracite samples is smaller than dry coal samples.Compared with dry coal samples,the increase of gas pressure has less effect on the adsorption of saturated coal samples.The moisture distribution in different water content coal samples are different.And water is mainly distributed in the micropores in coal samples with less moisture content.The gas adsorption amount decreases with the increase of moisture content,that means the moisture content has an inhibitory effect on the coal gas adsorption.But the inhibitory effects are different.The inhibitory effect caused by water in micropores is more apparent.With the increase of moisture content,the velocity of gas adsorption decreases and the time of adsorption equilibrium increases.