Free volume correction method of adsorbing capacity in volumetric isothermal adsorption experiment

Abstract

The invention discloses a free volume correction method of the adsorbing capacity in a volumetric isothermal adsorption experiment. The free volume correction method of the adsorbing capacity in the volumetric isothermal adsorption experiment comprises the steps of: performing an isothermal adsorption experiment on a test sample, wherein the adsorbate is helium, and obtaining the helium free spacevolumes of various helium equilibrium pressure points by calculation when the temperature T is obtained; performing piecewise linear fitting on the various helium equilibrium pressure points and thecorresponding helium free space volumes, so that a free space volume fitting equation is obtained; performing the isothermal adsorption experiment on the test sample, wherein the adsorbate is test gas; when a sample cylinder is at the temperature T, substituting various test gas equilibrium pressure points in the free space volume fitting equation, so that the test gas free space volumes of the sample cylinder at the various test gas equilibrium pressure points are obtained; and obtaining the adsorption increment and the accumulative adsorbing capacity of the test gas at the various equilibrium pressure points by calculation. According to the free volume correction method of the adsorbing capacity in the volumetric isothermal adsorption experiment in the invention, due to correction of thetest gas free space volume, the adsorption increment and the accumulative adsorbing capacity of the test gas at the various adsorption equilibrium pressure points are corrected; and thus, the relatively accurate adsorbing capacity is obtained.

Description

technical field [0001] The invention belongs to the technical field of coal-measure gas exploration and development, and specifically refers to a method for correcting the free volume of the adsorption amount in the volumetric isothermal adsorption experiment. Background technique [0002] Isothermal adsorption is an important means to measure the amount of adsorption. The volumetric method is widely used at home and abroad to calculate the amount of adsorption under different pressure conditions. In isothermal adsorption, various abnormal phenomena that do not conform to the Lange equation are often found. [0003] Abnormality 1: There is a phenomenon of maximum adsorption value, which often occurs in anthracite and activated carbon, that is, the isothermal adsorption capacity reaches the maximum value at a certain pressure, and the adsorption capacity decreases as the pressure further increases. This may be due to compressed coal. However, this phenomenon is not common; an...

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Problems solved by technology

[0008] Huang Meixin and others published "The correction of free volume and its influence on the isothermal adsorption of coal and shale" in the journal "Chinese Science and Technology Papers" (Volume 12, Issue 3, Page 279-282+289). The article is based on more For the purpose of accurately calculating the adsorption capacity of coal and shale in the volumetric isothermal adsorption experiment and improving the reliability of the evaluation of the adsorption capacity of coal and shale, based on the law of conservation of mass, the calculation formula of free volume was re-derived, and It was applied to the calculation of the adsorption capacity of coal and shale, and the influence of free volume on the isothermal adsorption capacity of coal and shale was quantitatively analyzed, but the correction method of free body during the test process was not explored. In addition, the article considers that the volume of free space is a fixed value

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