Relationship between desorption amount and temperature variation in the process of coal gas desorption

Ye, Qiusheng; Li, Chengwu; Yang, Tao; Wang, Yilin; Li, Zhenfei; Yin, Yifan

doi:10.1016/j.fuel.2022.126146

Cited by 20 publications

(12 citation statements)

References 31 publications

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“…The research shows that coal is a kind of porous medium with a highly complex pore structure, which contains a large number of pores of different pore sizes such as macropores, mesopores, and micropores, among which micropores provide a large enough adsorption surface area for coal adsorption of gas, which is the main place for gas adsorption and storage. ,, Coal can be considered an organic solid composed of carbon atoms (FC ad = 58.59%), and the carbon atoms within the coal are attracted by the surrounding carbon atoms to reach a state of force equilibrium. The coal body has an inner pore surface, and the carbon atoms on the side of the coal surface far from the coal body are in a suspended state, resulting in an unbalanced force and a tendency to move inward under the influence of the internal forces perpendicular to the coal body.…”

Section: Resultsmentioning

confidence: 99%

“…With the rapid development of the national economy, the total demand for coal energy is getting higher and higher, part of the coal mines have begun deep mining, and the coal seam is in the complex geological environment of “three highs and one disturbance”. − Coalbed methane (CBM), mainly composed of methane, is an associated gas generated by humic plants during the process of coal formation, which is reserved in the coal seam by adsorption and free. When the coal seam is affected by mining disturbance and high in situ stress, the dynamic adsorption equilibrium of gas is broken, and disasters such as coal and gas outburst and gas explosion are prone to occur during the mining process, which poses a serious threat to coal mine safety production. , …”

Section: Introductionmentioning

confidence: 99%

“…When the coal seam is affected by mining disturbance and high in situ stress, the dynamic adsorption equilibrium of gas is broken, and disasters such as coal and gas outburst and gas explosion are prone to occur during the mining process, which poses a serious threat to coal mine safety production. 5,6 To improve the utilization rate of CBM and reduce the disaster-causing degree of deep coal seam gas, it is necessary to precisely measure the reserve content of CBM. At present, the main methods commonly used to measure CBM content are direct and indirect.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Study on the Effect of the Degassing Vacuum Degree on the Adsorption Performance of Gas in Coal

Li,

Wang

et al. 2023

Energy Fuels

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To study the characteristics of the effect of the degassing vacuum degree on the gas adsorption performance of coal, gas adsorption experiments were performed on raw and particle coal under different degassing vacuum degree conditions. The degassing vacuum degree is measured in real time during the whole vacuum degassing experiment. The experimental results demonstrate that the higher the degassing vacuum degree, the greater the gas adsorption capacity of coal and the greater the growth rate of gas adsorption capacity. With the elevation of the degassing vacuum degree, the free energy of the pore surface in the coal body increases under vacuum conditions and the ability of the coal body to adsorb gas increases, which shows that the gas adsorption capacity rises. By comparing the difference in gas adsorption capacity of raw coal and particle coal under the identical degassing vacuum, it can be derived that the internal pore length of particle coal is shortened, the gas migration resistance reduces, and the adsorption potential of the micropore throat decreases. In the process of vacuum degassing, the binding capacity of coal pores to gas decreases and the residual gas capacity decreases. Therefore, compared with raw coal, the gas adsorption capacity of particle coal is significantly increased and the gas adsorption capacity of the coal sample is nearly doubled after the first crushing. The study of the effect of the degassing vacuum degree on the gas adsorption performance of coal is helpful to understanding the influence of residual gas in the coal before adsorption on the accuracy of gas adsorption capacity measurement so that the experimental measurement of gas adsorption is closer to the actual gas content of the coal seam.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Experimental Study on the Effect of the Degassing Vacuum Degree on the Adsorption Performance of Gas in Coal

Li,

Wang

et al. 2023

Energy Fuels

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“…Under an equilibrium adsorption pressure of 7 MPa, the amount of CH 4 adsorbed by coal can decrease by 60% when the temperature is increased from 22 to 102 °C . The gas adsorption/desorption experiments on raw coal specimens at different temperatures revealed that the thermal motion of methane molecules increased with increasing temperature, resulting in a decrease in the adsorption capacity. , …”

Section: Introductionmentioning

confidence: 99%

“…7 The gas adsorption/desorption experiments on raw coal specimens at different temperatures revealed that the thermal motion of methane molecules increased with increasing temperature, resulting in a decrease in the adsorption capacity. 8,9 The heat of adsorption can be divided into isosteric heat and ultimate heat, with isosteric heat referring to the instantaneous enthalpy change during the gas adsorption process and the heat released by an infinitely small number of gas molecules. 10 The ultimate heat of adsorption is the isosteric heat of adsorption as the pressure approaches zero.…”

Section: Introductionmentioning

confidence: 99%

Factors Influencing the Methane Adsorption Capacity of Coal and Adsorption Heat Variations

Wang,

Li,

Wang

et al. 2023

Energy Fuels

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Adsorption capacity is a key parameter to evaluate the underground storage capacity of natural gas and the reliability of CO2 sequestration. To explore the effects of temperature and pore structure and properties on adsorption capacity, the quantitative characterization of the effect of temperature on the adsorption capacity of coal and on changes in the heat of adsorption of coal samples during the adsorption process, nine coal samples with thermal maturities ranging from 0.47% to 5.16% vitrinite reflectance (R o) were analyzed by isothermal adsorption experiments at from 20 to 100 °C in 20 °C steps, and the pore structure was analyzed by low-temperature N2 and CO2 adsorption. Moreover, the isosteric heat based on a fixed amount of adsorption and the ultimate heat of CH4 adsorption in different rank coals were also analyzed. The results show that the adsorption capacity of all coals decreases with increasing temperatures, with the maximum volume adsorbed being 11.77–33.34 cm3/g at 20 °C and 9.87–28.99 cm3/g at 100 °C. The change in adsorption ranges from 1.90 to 14.18 cm3/g per 20 °C change, with the coals from 0.71% R o to 3.65% R o showing the least variability: 2.49 cm3/g for every 20 °C change. Coals are dominated by 0.3–0.8 nm micropores, and the isosteric heat of adsorption variation is influenced by the coal surface roughness and intermolecular forces during adsorption. With increasing coal rank, the ultimate heat of adsorption for coal follows the same trend as the adsorption capacity and is positively correlated with the volume and surface area of micropores. The adsorption capacity can be well predicted by the isosteric heat of adsorption only at temperatures ≥ 60 °C. The results can be beneficial for understanding the gas storage in deep reservoirs and promoting the efficient production of deep coalbed methane.

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Evolution of Thermodynamic Properties of Tectonic Coal with Mass Ratios Determined by Isothermal Adsorption Test

et al. 2023

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Relationship between desorption amount and temperature variation in the process of coal gas desorption

Cited by 20 publications

References 31 publications

Experimental Study on the Effect of the Degassing Vacuum Degree on the Adsorption Performance of Gas in Coal

Experimental Study on the Effect of the Degassing Vacuum Degree on the Adsorption Performance of Gas in Coal

Factors Influencing the Methane Adsorption Capacity of Coal and Adsorption Heat Variations

Evolution of Thermodynamic Properties of Tectonic Coal with Mass Ratios Determined by Isothermal Adsorption Test

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