Experimental study on methane diffusion kinetics in three typical metamorphic coals

Song, Haoran; Lin, Baiquan; Zhong, Zheng; Liu, Ting

doi:10.1016/j.fuel.2021.122601

Cited by 13 publications

(12 citation statements)

References 46 publications

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“…The effective diffusion coefficient of PCB samples of varying particle size was also positively correlated with the pore parameters, but the diffusion coefficient displayed the opposite trend, with a specific trend of 0.215 > 0.075 > 0.013 > 0.0065 mm. In the study by Song and Liu, this effect of particle size on diffusion was attributed to the size effect. , The pore volume and specific surface area of PCB samples increased as particle size decreased, whereas the diffusion coefficient decreased, indicating that the effect of particle size on the diffusion coefficient is greater than that of pore parameters, such as pore volume and surface area in coal matrix characteristics. Variations in the gas composition also cause variations in the diffusion coefficient.…”

Section: Discussionmentioning

confidence: 96%

“…Song and Liu obtained similar results and agreed that the size effect is the driving force behind this phenomenon. 23,24 Figure 4b reveals that the diffusion coefficient of the SM 0.215 mm particle size sample is significantly greater than that of the 0.075 mm particle size sample; the diffusion coefficient of the PCB sample is the greatest for the 0.215 mm particle size sample and smallest for the 0.0065 mm particle size sample; the trend of the diffusion coefficient is 0.215 > 0.075 > 0.013 > 0.0065 mm. Combining the two sets of data, it can be concluded that the diffusion coefficient is positively correlated with the size of coal matrix particles, i.e., beginning with the column sample, the diffusion coefficient decreases as the size of the coal matrix particles decreases.…”

Section: Characteristics Of Gas Diffusion In Coalmentioning

confidence: 98%

“…22,25 However, there were studies that demonstrated that the effective diffusion coefficient was negatively correlated with the particle size as the sample size decreased. 23,24 Based on the previous studies, it is inferred that the effective diffusion coefficient may not be suitable for characterizing gas diffusion when the sample size is different. Therefore, in this paper, we further analyze the diffusion coefficients of different samples and the differences between the effective diffusion coefficients as well as the conditions for using the effective diffusion coefficients in depth.…”

Section: Introductionmentioning

confidence: 99%

“…The effective diffusion coefficient was proposed to characterize the diffusion process of the gas due to the difficulty in obtaining the exact diffusion distance during the calculation of the diffusion coefficient . As the difference between the two parameters depends only on whether the effective diffusion path is calculated or not, these two parameters have been widely used by scholars to characterize the gas diffusion behavior. − The porosity of coal samples with different degrees of metamorphism was found to be positively correlated with the diffusion coefficient in previous studies, while studies on samples with different particle sizes demonstrated that the pore development was higher as the sample size decreased. , However, there were studies that demonstrated that the effective diffusion coefficient was negatively correlated with the particle size as the sample size decreased. , Based on the previous studies, it is inferred that the effective diffusion coefficient may not be suitable for characterizing gas diffusion when the sample size is different. Therefore, in this paper, we further analyze the diffusion coefficients of different samples and the differences between the effective diffusion coefficients as well as the conditions for using the effective diffusion coefficients in depth.…”

Section: Introductionmentioning

confidence: 99%

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Gas Diffusion Characteristics and Size Effect in Coal Particles with Different Degrees of Metamorphism

Zhai

Song

et al. 2023

Energy Fuels

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Coalbed methane (CBM) is a green unconventional energy source where the gas diffusion efficiency in coal directly limits the production capacity. Therefore, different gas adsorption experiments were used to determine the diffusion characteristics of coal samples with varying degrees of metamorphism. The influence law based on the gas type, pore structure, and coal sample size on the gas diffusion coefficient was analyzed, and the synergistic control effect of various factors on diffusion was discussed. The results show that when the particle size is the same, the diffusion coefficient of different gases shows the change rule of CO2 > N2 > CH4, and the diffusion coefficient of different samples is positively correlated with the degree of pore development. When the particle size is different, the diffusion coefficient is negatively correlated with the pore development degree and positively correlated with the sample particle size. The effective diffusion coefficient is consistent with the diffusion coefficient when the particle size of the sample is the same, and the effective diffusion coefficient is opposite to the diffusion coefficient when the particle size decreases. The analysis reveals that the diffusion coefficients of different gas are limited by the diameter of gas molecular dynamics, and the diffusion coefficient is reduced with the decrease in the diameter of the gas molecular dynamics. The change of diffusion coefficient caused by particle size change is positively correlated with the change of diffusion cross section caused by size effect. The difference between the effective diffusion coefficient and the diffusion coefficient mainly comes from whether the effective diffusion path is calculated. Therefore, when the particle size is constant, the effective diffusion coefficient can replace the diffusion coefficient to characterize the diffusion behavior. When the particle size is different, it is more appropriate to use the diffusion coefficient to characterize the gas diffusion behavior. The significance of the research findings in revealing gas transport in the coal matrix and coalbed methane formation is substantial.

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Section: Discussionmentioning

confidence: 96%

Section: Characteristics Of Gas Diffusion In Coalmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Gas Diffusion Characteristics and Size Effect in Coal Particles with Different Degrees of Metamorphism

Zhai

Song

et al. 2023

Energy Fuels

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“…Domestic and foreign scholars have done a lot of research on the problem of loss compensation in the process of gas content determination (Qi et al, 2007;Liu et al, 2013;Song et al, 2021;Yi et al, 2022). The established empirical/semi- Coal sample irradiation velocity curve (modified from Fu et al, 2008).…”

Section: Determination Of Gas Content In Tectonic Coal Based On Compe...mentioning

confidence: 99%

The characteristics of methane adsorption capacity and behavior of tectonic coal

Zhang

Zhang²,

Zhang³

et al. 2023

Front. Earth Sci.

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The research of methane adsorption on tectonic coal is an important content to gas disaster prevention and coalbed methane (CBM) exploration in outburst coal seams. Many projects of methane adsorption capacity and behavior of tectonic coal, such as adsorption difference between tectonic coal and its untectonic coal, adsorption evaluation of tectonic coal, factors for adsorption capacity of tectonic coal, gas-solid coupling feature in tectonic coal and supercritical adsorption phenomena of tectonic coal, were carried out by scientists. Combined with a long-term study on organic matter structure and methane adsorption of tectonic coal, the author summarized recent-years’ researches on adsorption capacity and behavior of tectonic coal-methane at home and abroad from the dispute of adsorption ability determination, the thermodynamic characterization of methane adsorption capacity, and the methane adsorption behavior of quantum chemical calculation of the adsorption and the gas content calculation based on loss compensation, respectively. It is believed that the coal structure controls the methane adsorption capacity and behavior characteristics of different tectonic coals, and from the perspective of thermodynamics, the adsorption capacity of different types of coals can be better distinguished. In the future, a more scientific and complete quantum chemical calculation of methane adsorption by tectonic coal and a compensation method based on instantaneous emission loss should be established, so as to better reveal the methane adsorption behavior of tectonic coal and the mechanism of coal and gas outburst. The research has a reference to fine research of coal adsorption and CBM exploration practices.

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Relationship Between Micropore Structure of Different Coal Ranks and Methane Diffusion

Pan

Cheng

et al. 2022

Nat Resour Res

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Experimental study on methane diffusion kinetics in three typical metamorphic coals

Cited by 13 publications

References 46 publications

Gas Diffusion Characteristics and Size Effect in Coal Particles with Different Degrees of Metamorphism

Gas Diffusion Characteristics and Size Effect in Coal Particles with Different Degrees of Metamorphism

The characteristics of methane adsorption capacity and behavior of tectonic coal

Relationship Between Micropore Structure of Different Coal Ranks and Methane Diffusion

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