Compositional shift of residual gas during desorption from anthracite and its influencing factors

Chen, Yilin; Qin, Yong; Luo, Zheng; Yi, Tongsheng; Wei, Chongtao; Wu, Caifang; Li, Guozhang

doi:10.1016/j.fuel.2019.03.144

Cited by 4 publications

(2 citation statements)

References 56 publications

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“…The smaller the coal particle size is, the bigger the specific surface area will be. Then, the fine-particle coal will present a higher adsorption capacity and adsorption rate. , For primary coal, the adsorption capacity is mainly determined by the pores with apertures below 10 nm . However, the adsorption capacity of deformed coal is mainly contributed by pores with diameters less than 8 nm .…”

Section: Introductionmentioning

confidence: 99%

Particle Size Effect and Temperature Effect on the Pore Structure of Low-Rank Coal

Wang

et al. 2021

ACS Omega

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High moisture content and high volatile content are typical characteristics of low-rank coal. To acquire the pore structure characteristics of low-rank coal accurately, the particle sizes and the pretreatment temperatures are two key parameters that should be considered when the low-pressure liquid-nitrogen adsorption is used. In this study, a low-rank coal sample was collected from Ordos Basin, and it was polished into four different particle sizes, 40−80 mesh, 80−120 mesh, 120−160 mesh, and 160−200 mesh, respectively. Besides, the low-rank coal samples are handled under seven various pretreatment temperatures (ranging from 120 to 300 °C); then, the pore structure characteristics of low-rank coal under various particle sizes and pretreatment temperatures are acquired. The dynamic change of pore volume and pore-specific surface area for low-rank coal is coincident. Under the same pretreatment temperatures, the mesopores' volume continuously decreases. When the pretreatment temperature reaches 300 °C, a faint increase in their volume is observed. These results mean the mesopores are damaged during the progressive pulverization and heating procedures. When it comes to the same particle sizes, the mesopores' volume also decreased with the increased pretreatment temperatures. Contrarily, the macropore volume is stable. This is mainly due to the decomposition of volatile matters and collapse of mesopores under the high pretreatment temperatures. However, the enrichment of ash in the mesopores could maintain the coal skeleton. The particle size effect and temperature effect mainly relate to the mesopores in low-rank coal, and the pores with the aperture below 5 nm contribute predominantly, followed by the pores with the aperture ranging from 5 to 10 nm.

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Section: Introductionmentioning

confidence: 99%

Particle Size Effect and Temperature Effect on the Pore Structure of Low-Rank Coal

Wang

et al. 2021

ACS Omega

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“…Therefore, coal and gas outburst may be related to the gas existing in the closed pores of the coal seam. Furthermore, the total gas content of an experimental coal sample generally includes lost gas, desorbed gas and residual gas (Chen et al, 2019). The residual gas may initially be sealed in closed pores in coal.…”

Section: Introductionmentioning

confidence: 99%

The Characteristics of Closed Pores in Coals With Different Ranks

2021

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The closed pores in coal seams influence the storage of coalbed methane. The investigation of closed pores characteristics for coals is of great significance in improving the production of coalbed methane and revealing the mechanism of coal and gas outburst. However, due to limitations in analytical techniques, the characteristics and evolution mechanism of closed pores in coals with different ranks are not sufficiently understood. In this paper, eight coal samples with different ranks were collected and characterized by small-angle X-ray scattering (SAXS) and low-temperature nitrogen adsorption (LTNA). The open and closed pores of coals with various ranks were studied, and the mechanism for evolution of closed pores during coalification was proposed. The results show that among eight coal samples with different ranks, the closed porosity of low-metamorphic coals is relatively lower, the closed porosity of medium-metamorphic coals is in the middle, and the closed porosity of high-metamorphic coals is relatively higher. The change in closed porosity for coals with different ranks may be related to varieties of the molecular structure of coals. The low-metamorphic coals have more disordered arrangement of molecular structure and easily form connected pores. Therefore, the closed porosity in low-metamorphic coals is low. The aromatization of medium-metamorphic coals turns aliphatic chains into closed aromatic rings, and the closed porosity of these coals also increases. When coals reach a high degree of metamorphism, polycondensation compacts the coal macromolecular structure, providing for easy formation of closed pores between aromatic condensed rings, so the closed porosity is obviously increased in high-metamorphic coals. This study has dual significance in advancing the understanding of open and closed pores in coals and the mechanism of coal and gas outburst.

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Experimental study of coalbed methane thermal recovery

Cao

Chen

Yang

et al. 2020

Energy Science & Engineering

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Extracting coalbed methane is challenging due to the strong gas adsorption capacity and low matrix permeability of the coalbed. Recently, thermal recovery methods have been tested to promote methane recovery. In this study, anthracite samples were heated to different temperatures to investigate the internal pressure variation and microstructure changes. It was found that higher temperature resulted in higher internal pressure. At low temperatures, the increase in the internal pressure was mainly due to gas desorption. At 500°C, thermal cracking gases provided the main contribution to the high internal pressures, as more gaseous products were generated at the higher temperature. In addition, the microstructure of coal significantly changed after combustion, including the increased pore volume, the increased specific surface area, and the generation of microfractures. These changes could potentially increase the porosity and permeability of coal. Thus, high‐temperature thermal treatments not only provided energy for gas desorption and organic matter decomposition but also improved conditions for gas transport.

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Compositional shift of residual gas during desorption from anthracite and its influencing factors

Cited by 4 publications

References 56 publications

Particle Size Effect and Temperature Effect on the Pore Structure of Low-Rank Coal

Particle Size Effect and Temperature Effect on the Pore Structure of Low-Rank Coal

The Characteristics of Closed Pores in Coals With Different Ranks

Experimental study of coalbed methane thermal recovery

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