Fractal characteristics of pore structures in 13 coal specimens: Relationship among fractal dimension, pore structure parameter, and slurry ability of coal

Zhu, Jiachen; Liu, Jianzhong; Yang, Yongrong; Cheng, Jun; Zhou, Junhu; Cen, Kefa

doi:10.1016/j.fuproc.2016.04.026

Cited by 107 publications

(66 citation statements)

References 46 publications

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“…Furthermore, multilayer adsorption occurred at a relative pressure of 0.5 < P/P 0 < 0.95 (region 2), when the adsorption curves gradually increased. The adsorption curves then increased sharply as the relative pressure exceeded 0.95, indicating that capillary condensation occurred in accordance with the Kelvin equation, increasing the quantity of adsorbed nitrogen [39].…”

Section: Lp-n 2 -Ad Isotherms and Pore Structure Parameters Analysis mentioning

confidence: 75%

Damage Effects and Fractal Characteristics of Coal Pore Structure during Liquid CO2 Injection into a Coal Bed for E-CBM

Wei

et al. 2018

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Pore structure has a significant influence on coal-bed methane (CBM) enhancement. Injecting liquid CO 2 into coal seams is an effective way to increase CBM recovery. However, there has been insufficient research regarding the damage effects and fractal characteristics of pore structure at low temperature induced by injecting liquid CO 2 into coal samples. Therefore, the methods of low-pressure nitrogen adsorption-desorption (LP-N 2 -Ad) and mercury intrusion porosimetry (MIP) were used to investigate the damage effects and fractal characteristics of pore structure with full aperture as the specimens were frozen by liquid CO 2 . The adsorption isotherms revealed that the tested coal samples belonged to type B, indicating that they contained many bottle and narrow-slit shaped pores. The average pore diameter (APD; average growth rate of 18.20%), specific surface area (SSA; average growth rate of 7.38%), and total pore volume (TPV; average growth rate of 18.26%) increased after the specimens were infiltrated by liquid CO 2 , which indicated the generation of new pores and the transformation of original pores. Fractal dimensions D 1 (average of 2.58) and D 2 (average of 2.90) of treated coal samples were both larger the raw coal (D 1 , average of 2.55 and D 2 , average of 2.87), which indicated that the treated specimens had more rough pore surfaces and complex internal pore structures than the raw coal samples. The seepage capacity was increased because D 4 (average of 2.91) of the treated specimens was also higher than the raw specimens (D 4 , average of 2.86). The grey relational coefficient between the fractal dimension and pore structure parameters demonstrated that the SSA, APD, and porosity positively influenced the fractal features of the coal samples, whereas the TPV and permeability exerted negative influences.

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Section: Lp-n 2 -Ad Isotherms and Pore Structure Parameters Analysis mentioning

confidence: 75%

Damage Effects and Fractal Characteristics of Coal Pore Structure during Liquid CO2 Injection into a Coal Bed for E-CBM

Wei

et al. 2018

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“…A rule is adopted to remove a part of these small cubes and the number of the remaining small cubes is N b1 . After undergoing k such operations, the side length of the remaining cubes is a k = R/m k and the total number is calculated using Equation 1 [54,55].…”

Section: Mercury Intrusion Methodsmentioning

confidence: 99%

Characterization of Pores and Fractures in Soft Coal from the No. 5 Soft Coalbed in the Chenghe Mining Area

et al. 2018

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The characteristics of the pore structure and gas migration in soft coalbeds are the premise of evaluating gas discharge in soft coalbeds. To explore the pore structure characteristics of soft coal masses, the No. 5 soft coalbed in the eastern zone of Chenghe Mining Area, was investigated and compared with the No. 5 hard coalbed in the western zone. By using a mercury intrusion method, low-temperature liquid nitrogen adsorption, and scanning electron microscopy (SEM), the pore structure characteristics of the No. 5 coalbed were explored. Moreover, based on fractal theory, the pore structure of coal was characterized. The results showed the pores in soft coal mainly appeared as small pores and micropores in which the small pores accounted for nearly half of the total pore volume. Mesopores and macropores were also distributed throughout the soft coal. The mercury-injection and mercury-ejection curves of soft coal showed significant hysteresis loops, implying that pores in coal samples were mainly open while the mercury-injection curve of hard coal was consistent with its mercury-ejection curve, showing no hysteresis loop while having an even segment, which indicated that closed pores occupied the majority of the pore volume in the coal samples. The curves of low-temperature nitrogen adsorption of soft coal all follow an IV-class isotherm. Moreover, the fractal dimensions of soft coal are respectively larger than the fractal dimensions of hard coal. It can be seen that the characterization of pores and fractures of the soft coal was different from the hard coal in the western distinct of the old mining area. The gas prevention and control measures of soft coal should be formulated according to local conditions.

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“…As illustrated in Figure 7d, the adsorption process is divided into three stages. This is because the coking coal pore size is mainly distributed in the mesoporous range and the macroporous range and there are almost no micropores [21]. The first stage reflected that the organic matter was directly adsorbed on the surface active sites of coking coal and its macropores and the large slope indicated that the reaction was rapid at this stage.…”

Section: Adsorption Isothermsmentioning

confidence: 99%

Adsorption of Organic Constituents from Reverse Osmosis Concentrate in Coal Chemical Industry by Coking Coal

Qin

Zhang

et al. 2019

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To solve the unwieldy problem of coal chemical wastewater reverse osmosis concentrate (ROC), a novel treatment method in which coking coal was used to adsorb the organic from ROC and the adsorption mechanism involved was investigated. The results showed that the organic components in the ROC of coal chemical industry can be effectively absorbed by the coking coal and the total organic carbon, UV254 and chromaticity of treated ROC reduced by 70.18%, 70.15% and 59.55%, respectively, at the coking coal dosage of 80 g/L. The isothermal adsorption data were fitted to the Langmuir model well. The kinetics were expressed well by the quasi-second-order kinetic model. The intragranular diffusion model and the BET (Acronym for three scientists: Brunauer–Emmett–Teller) test showed that the adsorption occurred mainly on the surface of the coking coal and its macropores and mesopores. When the pollutants further diffused to the mesopores and micropores, the adsorption rate decreased. The result of X-ray photoelectron spectroscopy and fourier transform infrared spectroscopy spectra showed that the coking coal mainly adsorbed the nitrogen and oxygen species and the halogenated hydrocarbon organic compounds in the ROC. The chlorinated hydrocarbons and heterocyclic organics in ROC are adsorbed on the surface of coking coal.

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Fractal characteristics of pore structures in 13 coal specimens: Relationship among fractal dimension, pore structure parameter, and slurry ability of coal

Cited by 107 publications

References 46 publications

Damage Effects and Fractal Characteristics of Coal Pore Structure during Liquid CO2 Injection into a Coal Bed for E-CBM

Damage Effects and Fractal Characteristics of Coal Pore Structure during Liquid CO2 Injection into a Coal Bed for E-CBM

Characterization of Pores and Fractures in Soft Coal from the No. 5 Soft Coalbed in the Chenghe Mining Area

Adsorption of Organic Constituents from Reverse Osmosis Concentrate in Coal Chemical Industry by Coking Coal

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