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Experimental Study of the Pore Structure and Gas Desorption Characteristics of a Low-Rank Coal: Impact of Moisture

[Image: see text] Coal–water interactions have a prominent impact on the prediction of coal mine gas disasters and coalbed methane extraction. The change of characteristics in the microscopic pores of coal caused by the existence of water is an important factor affecting the diffusion and migration...

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Autores principales: Chen, Mingyi, Chen, Xiaoyun, Zhang, Xuejie, Tian, Fuchao, Sun, Weili, Yang, Yumeng, Zhang, Tonghao
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2022
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9608427/
https://www.ncbi.nlm.nih.gov/pubmed/36312393
http://dx.doi.org/10.1021/acsomega.2c03805
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author Chen, Mingyi
Chen, Xiaoyun
Zhang, Xuejie
Tian, Fuchao
Sun, Weili
Yang, Yumeng
Zhang, Tonghao
author_facet Chen, Mingyi
Chen, Xiaoyun
Zhang, Xuejie
Tian, Fuchao
Sun, Weili
Yang, Yumeng
Zhang, Tonghao
author_sort Chen, Mingyi
collection PubMed
description [Image: see text] Coal–water interactions have a prominent impact on the prediction of coal mine gas disasters and coalbed methane extraction. The change of characteristics in the microscopic pores of coal caused by the existence of water is an important factor affecting the diffusion and migration of gas in coal. The low-pressure nitrogen adsorption experiments and gas desorption experiments of a low-rank coal with different equilibrium moisture contents were conducted. The results show that both the specific surface area and pore volume decrease significantly as the moisture content increases, and the micropores (pore diameter <10 nm) are most affected by the water adsorbed by coal. In particular, for a water-equilibrated coal sample at 98% relative humidity, micropores with pore sizes smaller than 4 nm as determined by the density functional theory model almost disappear, probably due to the blocking effects of water clusters and capillary water. In this case, micropores with a diameter less than 10 nm still contribute most of the specific surface area for gas adsorption in coal. Furthermore, the fractal dimensions at relative pressures of 0–0.5 (D(1)) and 0.5–1 (D(2)) calculated by the Frenkel–Halsey–Hill model indicate that when the moisture content is less than 4.74%, D(1) decreases rapidly, whereas D(2) shows a slight reduction as the moisture content increased. In contrast, when the moisture content exceeds 4.74%, further increases in the moisture content cause D(2) to decrease significantly, while there is nearly no change for D(1). The correlation analyses show that the ultimate desorption volume and initial desorption rate are closely related to the fractal dimension D(1), while the desorption constant (K(t)) mainly depends on the fractal dimension D(2). Therefore, the gas desorption performances of coal have a close association with the pore properties of coal under water-containing conditions, which indicate that the fluctuation in moisture content should be carefully considered in the evaluation of gas diffusion and migration performances of in situ coal seams.
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spelling pubmed-96084272022-10-28 Experimental Study of the Pore Structure and Gas Desorption Characteristics of a Low-Rank Coal: Impact of Moisture Chen, Mingyi Chen, Xiaoyun Zhang, Xuejie Tian, Fuchao Sun, Weili Yang, Yumeng Zhang, Tonghao ACS Omega [Image: see text] Coal–water interactions have a prominent impact on the prediction of coal mine gas disasters and coalbed methane extraction. The change of characteristics in the microscopic pores of coal caused by the existence of water is an important factor affecting the diffusion and migration of gas in coal. The low-pressure nitrogen adsorption experiments and gas desorption experiments of a low-rank coal with different equilibrium moisture contents were conducted. The results show that both the specific surface area and pore volume decrease significantly as the moisture content increases, and the micropores (pore diameter <10 nm) are most affected by the water adsorbed by coal. In particular, for a water-equilibrated coal sample at 98% relative humidity, micropores with pore sizes smaller than 4 nm as determined by the density functional theory model almost disappear, probably due to the blocking effects of water clusters and capillary water. In this case, micropores with a diameter less than 10 nm still contribute most of the specific surface area for gas adsorption in coal. Furthermore, the fractal dimensions at relative pressures of 0–0.5 (D(1)) and 0.5–1 (D(2)) calculated by the Frenkel–Halsey–Hill model indicate that when the moisture content is less than 4.74%, D(1) decreases rapidly, whereas D(2) shows a slight reduction as the moisture content increased. In contrast, when the moisture content exceeds 4.74%, further increases in the moisture content cause D(2) to decrease significantly, while there is nearly no change for D(1). The correlation analyses show that the ultimate desorption volume and initial desorption rate are closely related to the fractal dimension D(1), while the desorption constant (K(t)) mainly depends on the fractal dimension D(2). Therefore, the gas desorption performances of coal have a close association with the pore properties of coal under water-containing conditions, which indicate that the fluctuation in moisture content should be carefully considered in the evaluation of gas diffusion and migration performances of in situ coal seams. American Chemical Society 2022-10-14 /pmc/articles/PMC9608427/ /pubmed/36312393 http://dx.doi.org/10.1021/acsomega.2c03805 Text en © 2022 The Authors. Published by American Chemical Society https://creativecommons.org/licenses/by-nc-nd/4.0/Permits non-commercial access and re-use, provided that author attribution and integrity are maintained; but does not permit creation of adaptations or other derivative works (https://creativecommons.org/licenses/by-nc-nd/4.0/).
spellingShingle Chen, Mingyi
Chen, Xiaoyun
Zhang, Xuejie
Tian, Fuchao
Sun, Weili
Yang, Yumeng
Zhang, Tonghao
Experimental Study of the Pore Structure and Gas Desorption Characteristics of a Low-Rank Coal: Impact of Moisture
title Experimental Study of the Pore Structure and Gas Desorption Characteristics of a Low-Rank Coal: Impact of Moisture
title_full Experimental Study of the Pore Structure and Gas Desorption Characteristics of a Low-Rank Coal: Impact of Moisture
title_fullStr Experimental Study of the Pore Structure and Gas Desorption Characteristics of a Low-Rank Coal: Impact of Moisture
title_full_unstemmed Experimental Study of the Pore Structure and Gas Desorption Characteristics of a Low-Rank Coal: Impact of Moisture
title_short Experimental Study of the Pore Structure and Gas Desorption Characteristics of a Low-Rank Coal: Impact of Moisture
title_sort experimental study of the pore structure and gas desorption characteristics of a low-rank coal: impact of moisture
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9608427/
https://www.ncbi.nlm.nih.gov/pubmed/36312393
http://dx.doi.org/10.1021/acsomega.2c03805
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