CHANGE OF THERMODYNAMIC CHARACTERISTICS OF THE CARBON ADSORBENT FAS-3 AT ADSORPTION OF BENZENE

Впервые проведены комплексные исследования адсорбционной деформации - сорбострикции микропористого углеродного адсорбента ФАС-3 при адсорбции паров бензола из потока газа-носителя - азота в неравновесных условиях. Изучены изотермы адсорбции паров бензола микропористым углеродным адсорбентом ФАС-3 в равновесных условиях. Были представлены формулы и проведены расчеты изменений энтропии и внутренней энергии адсорбента в адсорбционном процессе. For the first time, complex studies were carried out on adsorption deformation - sorbostriction of the microporous carbon adsorbent FAS-3 at adsorption of benzene vapors from the flow of carrier gas - nitrogen in non-equilibrium conditions. Adsorption isotherms of benzene vapors by the microporous carbon adsorbent FAS-3 under equilibrium conditions has been studied. Calculations of changes in the entropy and internal energy of the adsorbent in the adsorption process were performed.

Influence of gas migration on permeability of soft coalbed methane reservoirs under true triaxial stress conditions

The permeability of the coal body is the key parameter restricting the efficient extraction of coalbed methane, and scholars have analysed it from two angles of the change of stress state and porosity of the coal body. However, there is still a lack of study on the mechanism of gas migration and movement in soft coalbed methane reservoir under the coupling between the true triaxial stress field (maximum principal stress σ 1 > intermediate principal stress σ 2 > minimum principal stress σ 3 ) and the gas pressure field. In this paper, the coal gas adsorption and seepage experiments are conducted through the self-developed true triaxial ‘gas–solid’ coupled coal mass seepage system with gas as the adsorption and seepage medium and coal briquette taking the place of soft coalbed methane reservoirs. Furthermore, the coal gas adsorption deformation model and the permeability evolution model taking gas adsorption into account are developed. Through analysis of both experimental and theoretic results, the main conclusions are drawn as follows: (i) With the increase in gas pressure, the adsorption deformation variation of coal mass is divided into a slow growth zone, a stable growth zone and a rapid growth zone. (ii) The gas adsorption deformation model developed can predict the variation trend of coal mass adsorption volumetric strains for different types of soft coalbeds, and the fitting variance of experimental and theoretical volumetric strains is above 98%. (iii) With the increase in maximum principal stress difference, the coal permeability variation curve shows two obvious turning points, which can be divided into a slow reduction zone, a rapid reduction zone and a steady reduction zone. (iv) The permeability model of coal mass considering the gas adsorption effect can reflect the variation characteristics of permeability in the rapid reduction zone, and the overall fitting variance of experimental and theoretical permeabilities is above 91%. The above results could provide a reliable experimental and theoretical basis for improving coalbed methane extraction rates.

ADSORPTION DEFORMATION OF MICROPOROUS CARBON ADSORBENT FAS AT ADSORP-TION OF WATER AND ACETONE VAPORS

For the first time, complex studies were carried out on adsorption deformation – sorbostriction of microporous carbon adsorbent FAS at adsorption of water and acetone vapors from the flow of carrier gas – nitrogen in non-equilibrium conditions. The results of this phenomenon were analyzed and the laws of the sorption of the microporous carbon adsorbent FAS during the adsorption of substances of different classes and different purposes in non-equilibrium conditions are established. In work a microporous carbon adsorbent FAS, obtained on the basis of furfural was used. Active coals on the basis of thermosetting plastics grades of FAS are significantly better than commercially-produced carbon adsorbents based on coal and peat on their mechanical properties and low ash content at a much greater development of the volume of the adsorbent micropores. We used the facility for studies of adsorption deformation of a solid adsorbent, manufactured in the Institute of Physical Chemistry and Electrochemistry of RAS. For the measurements we used a flow dilatometer, allowing measuring the adsorption deformation of the adsorbent while passing through it portions of the test substance or mixture in the carrier gas flow. It is shown that exit time of curves of sorbostriction to the maximum is individually for each of the studied substances, which enables you to use the effect of sorbostriction to detect the presence of certain substances in the mixture. The results of the wave sorbostriction of microporous carbon adsorbent FAS at adsorption of water and acetone vapors from the flow of carrier gas - nitrogen allow to conclude on the high selectivity of adsorption and the possibility of using the adsorbent as a sensor to control the content of these substances in a flow of nitrogen.

Experimental study of the moisture content influence on CH4 adsorption and deformation characteristics of cylindrical bituminous coal core

Moisture content in coal is an important factor affecting the coal seam gas extraction. It directly affects the storage and flow of gas in bituminous coal. In this paper, the cylindrical bituminous coal cores of Xutuan coal mine in Huaibei coal mine group were studied as experimental objects, using the laboratory self-designed experimental device Gas Adsorption and Strain Testing Apparatus system. The influence of the bituminous coal moisture content on gas adsorption characteristics was studied. Drying experiments of coal samples showed that they lose the original moisture content following the exponential decay function of time. At wetting, the saturated moisture content in coal samples increased following the Exponential Association function of time. The experimental results show that the average original moisture content and average saturated moisture content of raw coal samples are 1.3 and 2.4%, respectively. On this basis, the gas adsorption experiments on samples with different moisture contents under different gas pressures were carried out. With the moisture content increase, the gas adsorption capacity and saturation value decreased and the decrease rate gradually reduced. The single exponential decay function describes the gas adsorption capacity dependence on moisture content. Moisture content also affects the adsorption deformation of bituminous coal. At high moisture content, the adsorption deformation of bituminous coal is less.

SORBOSTRICTION OF MICROPOROUS CARBON ADSORBENT FAS-3 AT ADSORPTION OF ORGANIC SUBSTANCES VAPORS FROM NITROGEN FLOW

For the first time, complex studies were carried out on adsorption deformation – sorbostriction of microporous carbon adsorbent FAS-3 at adsorption of hexane, benzene and carbon tetrachloride from the flow of carrier gas – nitrogen in non-equilibrium conditions. The results of this phenomenon were analyzed. In work a microporous carbon adsorbent FAS-3, obtained on the basis of furfural was used. Active coals on the basis of thermosetting plastics grades of FAS are significantly better than commercially-produced carbon adsorbents based on coal and peat on their mechanical properties and low ash content at a much greater development of the volume of the adsorbent micropores. We used the facility for studies of adsorption deformation of a solid adsorbent, manufactured in the Institute of Physical Chemistry and Electrochemistry of RAS. For the measurements we used a flow dilatometer, allowing measuring the adsorption deformation of the adsorbent while passing through it portions of the test substance or mixture in the carrier gas flow. It is shown that values of the maxima on the curves of deformation increase with increasing the concentrations of the components of the mixture. The area under the curve of barbastelle depends on the amount of injected material in a flow of carrier gas. Exit time curves of barbastelle to the maximum is individually for each of the studied substances, which enables you to use the effect of barbastelle to detect the presence of certain substances in the mixture. The results of the wave sorbostriction of microporous carbon adsorbent FAS-3 at adsorption of benzene, hexane, carbon tetrachloride from the flow of carrier gas - nitrogen allow to conclude on the high selectivity of adsorption and the possibility of using the adsorbent as a sensor to control the content of these substances in a flow of nitrogen.For citation:Zaytsev D.S., Tvardovskiy A.V., Shkolin A.V., Fomkin A.A. Sorbostriction of microporous carbon adsorbent FAS-3 at adsorption of organic substances vapors from nitrogen flow. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 4. P. 54-59.