水分对无烟煤瓦斯吸附影响的低场核磁试验研究

为研究水分对无烟煤瓦斯吸附的影响,以山西晋城集团王台铺煤矿无烟煤为研究对象,利用低场核磁共振技术,研究了煤样在不同水分含量下的核磁共振T2谱图,分析了T2谱图核磁信号与瓦斯吸附量的关系。结果表明:煤中水分质量分数较大时,水分在微孔、小孔、中大孔内均有分布;水分含量较小时,水分主要存在于微孔内。瓦斯吸附量随水分增加而减少,但水分对煤瓦斯吸附的抑制程度不同,水分质量分数从0增加到1.92%,水分主要存在于微孔隙中,瓦斯吸附量显著降低;而水分质量分数从1.92%增加到3.09%时,水分主要在小孔隙及中大孔隙内增加,瓦斯吸附量降低幅度较小。微孔隙中水分对瓦斯吸附的抑制作用较明显,随含水量增加,瓦斯吸附速度逐渐降低,吸附平衡所需时间增大。

Experimental study of the impact of the moisture content on the coal gas adsorption through the low-field NMR relaxation method

This article is intended to take the Shanxi Jincheng Wangtaipu anthracite coalmine as the study objective so as to disclose the influence or impact of different moisture contents on the anthracite gas adsorption with the low-field NMR technique and gain the NMR spectrum of the gas adsorption in the coal samples at the presence of different moisture contents.The experiment we have done has explored the nuclear magnetic signals of T2 spectrum and analyzed the relation between the nuclear magnetic signals of T2 spectrum and the anthracite gas adsorption,which lead us to make a conclusion of the low-field NMR technique experiment.Furthermore,the distribution of the moisture in the coal samples of different moisture contents proves to be various.The results of the experimental study show that:as in a case study sample,when the coal samples contain greater moisture content,its water content tends to be distributed in the micropores,mesopores and macropores.And,in contrast,when the water content is mainly distributed in the micropores under the condition if the coal samples contain less moisture content,the said water content in the different coal samples may tend to change differently.For example,in the process of the gas adsorption,with the increase of the adsorption time,the water content in the mesopores tends to be reduced in the coal sample.However,the water in the micropores may gradually move into the tiny pores.And,if the water content in the mesopores is discharged due to the competitive nature of methane in the coal sample,the water moisture in the micropores may not change obviously with the increase of the ad sorption time,for in the coal samples there exists smaller water content.The gas adsorption amount may begin to decrease when the moisture content increases,which suggests that the moisture content has an inhibitory effect on the coal gas adsorption.But the inhibitory effects of the moisture content can also be various.Since the moisture is mainly existing in the micropores,the gas adsorption can be significantly reduced when the moisture content increases from 0 to 1.92％.Furthermore,when the moisture con tent increases from 1.92％ to 3.09％,the increase of the moisture content would be mainly distributed in the mesopores and macropores.And,in turn,there will be a weakening situation of the decreasing tendency of the gas adsorption.Thus,it would be more apparent to see the inhibitory effect caused by the moisture content change.That is to say,when the moisture content increa ses,the velocity of the gas adsorption tends to decrease,so as to reach a period of the gas adsorption equilibrium.