Thermodynamic models for swelling of unconfined coal due to adsorption of mixed gases

Liu, Jinfeng; Peach, C. J.; Zhou, Hongwei; Spiers, Christopher J.

doi:10.1016/j.fuel.2015.04.070

Cited by 19 publications

(7 citation statements)

References 36 publications

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“…They also agree with the predictions of thermodynamic models for the effects of stress state on sorption and on sorption-induced swelling presented by these authors for two-component sorbent-sorbate system such as coal plus CO 2 or CH 4 . (see also Liu et al, 2015 andLiu et al, 2016).…”

Section: Swelling Stress Development In the Presence Of Co 2 : Phenomenology And Mechanismmentioning

confidence: 98%

Swelling stress development in confined smectite clays through exposure to CO2

Zhang

Jong

Spiers

et al. 2018

International Journal of Greenhouse Gas Control

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Section: Swelling Stress Development In the Presence Of Co 2 : Phenomenology And Mechanismmentioning

confidence: 98%

Swelling stress development in confined smectite clays through exposure to CO2

Zhang

Jong

Spiers

et al. 2018

International Journal of Greenhouse Gas Control

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“…In the process of methane adsorption, after methane molecules are adsorbed on the pore surfaces of coal, the coal matrix will undergo a swelling deformation. The degree of swelling deformation increases with the increase of adsorption quantity, and the heat released in the adsorption process will aggravate the degree of swelling deformation (Gorucu et al, 2007;Wang et al, 2010;Liu et al, 2015;Pan et al, 2015). The swelling deformation of the coal matrix not only compresses the pore space but also causes the contact between particles inside the coal to become closer, which reduces the resistivity and enhances the conductivity of the coal (Liu, 2017).…”

Section: Matrix Swelling and Shrinkagementioning

confidence: 99%

An Experimental Study on the Conductivity Changes in Coal during Methane Adsorption‐Desorption and their Influencing Factors

Chen

Guo

et al. 2019

Acta Geologica Sinica (Eng)

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During the processes of methane adsorption and desorption, the internal structure of coal changes, accordingly leading to changes in electrical conductivity. In this paper, using low rank coal seams of the Yan'an Formation in the Dafosi field as the research subject, the relationship between coal resistivity, methane adsorption quantity, and equilibrium pressure is analyzed through proximate analysis, mercury injection tests, low temperature liquid nitrogen adsorption tests, and coal resistivity measurements during methane adsorption and desorption. The results show that during the process of pressure rise and methane adsorption, the conductivity of coal increases, resulting from heat release from methane adsorption, coal matrix swelling and adsorbed water molecules replaced by methane, but the resistivity reduction gradually decreases. The relationship between coal resistivity and methane adsorption quantity and equilibrium pressure can be described by a quadratic function. During the processes of depressurization and desorption, the resistivity of coal rebounds slightly, due to decalescence of methane desorption, coal matrix shrinkage and water-gas displacement, and the relationship coincides with a linear function. Methane adsorption leads to irreversible changes in coal internal structure and enhances the coal conductivity, and resistivity cannot be restored to the initial level even after methane desorption. The resistivity and reduction rate of durain are higher than those of vitrain, with relatively greater homogeneous pore throat structure and fewer charged particles in the double electric layer. In addition, moisture can enhance the conductivity of coal and makes it change more complexly during methane adsorption and desorption.

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“…According to Equation (4), the coal matrix deformation induced by nitrogen or methane is obtained. From Equations (7), (22), and (23), the model of nitrogen-induced shrinking deformation of the coal matrix is obtained.…”

Section: Shrinking Model In Methane and Nitrogen Desorptionmentioning

confidence: 99%

Coal Matrix Deformation and Pore Structure Change in High-Pressure Nitrogen Replacement of Methane

Song

et al. 2018

Energies

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Abstract:Coal matrix deformation is one of the main controlling factors for coal reservoir permeability changes in nitrogen foam fracturing. The characteristics and mechanism of coal matrix deformation during the process of adsorption/desorption were studied by isothermal adsorption/desorption experiments with methane and nitrogen. Based on the free-energy theories, the Langmuir equation, and elastic mechanics, mathematical models of coal matrix deformation were developed and the deformation characteristics in adsorption/desorption processes were examined. From the study, we deduced that the coal matrix swelling, caused by methane adsorption, was a Langmuir-type relationship with the gas pressure, and exponentially increased as the adsorption quantity increased. Then, the deformation rate and amplitude of the coal matrix decreased gradually with the increase of the pressure. At the following stage, where nitrogen replaces methane, the coal matrix swelling continued but the deformation amplitude decreased, which was only 19.60% of the methane adsorption stage. At the mixed gas desorption stage, the coal matrix shrank with the reduction of pressure and the shrinkage amount changed logarithmically with the pressure, which had the hysteresis effect when compared with the swelling in adsorption. The mechanism of coal matrix deformation was discussed through a comparison of the change of micropores, mesopores, and also part macropores in the adsorption process.

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Thermodynamic models for swelling of unconfined coal due to adsorption of mixed gases

Cited by 19 publications

References 36 publications

Swelling stress development in confined smectite clays through exposure to CO2

Swelling stress development in confined smectite clays through exposure to CO2

An Experimental Study on the Conductivity Changes in Coal during Methane Adsorption‐Desorption and their Influencing Factors

Coal Matrix Deformation and Pore Structure Change in High-Pressure Nitrogen Replacement of Methane

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