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基于热力学原理及物理吸附机理,建立煤体吸附液氮的吸附层厚度理论,数值计算分析了孔径及吸附平衡压力对吸附层厚度(吸附层数)的影响。研究结果表明:在液氮吸附过程中,相对压力较小时,吸附层厚度随压力增大缓慢增厚,而相对压力约为0.9时,吸附层厚度出现拐点,吸附层厚度随相对压力迅速增大。同一吸附压力下,吸附层厚度(吸附层数)随孔径增大迅速减小至某一定值。相对吸附压力增大时,较大孔半径中(约大于50 nm),液氮吸附层厚度增量基本一样;但在小孔径中,液氮吸附层厚度变化较大,且孔径越小,吸附层厚度增量越大。而低温液氮吸附过程中,随吸附压力的变化吸附量与吸附层厚度具有相同的规律。
Based on the principle of thermodynamics and physical adsorption mechanism, the theory of adsorption layer thickness for liquid nitrogen adsorbed on coal was established. The influence of pore size and adsorption equilibrium pressure on the adsorption layer thickness (adsorption layer number) was numerically calculated. The results show that when the relative pressure is small, the thickness of adsorption layer slowly increases with the increase of pressure, while the relative pressure is about 0.9, the thickness of adsorption layer shows an inflection point, and the thickness of adsorption layer increases rapidly with the relative pressure . Under the same adsorption pressure, the thickness of adsorption layer (adsorption layer) decreases rapidly with the increase of pore diameter to a certain value. When the relative adsorption pressure is increased, the increase of the thickness of liquid nitrogen adsorption layer is basically the same in the larger pore radius (more than about 50 nm); however, in the small pore diameter, the thickness of the liquid nitrogen adsorption layer changes greatly and the smaller the pore size is, The greater the increase in layer thickness. In the process of cryogenic liquid nitrogen adsorption, the adsorption amount and adsorption layer thickness have the same rule with the change of adsorption pressure.