Dielectric anisotropy effects on the microwave-induced thermodynamic response of coal: Numerical simulations and experiments

Zhao, Yue; Gao, Yirui; Sun, Zhuang; Gao, Sen; Sun, Chuncheng

doi:10.1016/j.fuel.2022.125038

Cited by 12 publications

(3 citation statements)

References 54 publications

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“…8,9 The response of the medium to microwave depends on its own dielectric characteristics. 10,11 In the study of the microwave removal of organic sulfur in coal, the microwave absorption performance of organic sulfur in coal needs to be determined first.…”

Section: Introductionmentioning

confidence: 99%

“…By taking advantage of the difference in microwave absorption capacity between coal matrix and organic sulfur compounds, the organic sulfur compounds in coal can generate local high temperature and dissociate reaction through microwave radiation within a very short time before the coal matrix is decomposed 8,9 . The response of the medium to microwave depends on its own dielectric characteristics 10,11 . In the study of the microwave removal of organic sulfur in coal, the microwave absorption performance of organic sulfur in coal needs to be determined first.…”

Section: Introductionmentioning

confidence: 99%

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Microwave absorption properties and quantum chemistry of organic sulfur compounds in coal

Tao

Wang

et al. 2023

Asia-Pacific J Chem Eng

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The microwave absorption properties of dielectrics determine the promotion degree of microwave energy to chemical reaction. The wave‐absorbing characteristics of organic sulfur compounds in high‐sulfur coking coal need to be studied to improve the efficiency of microwave desulfurization of coal. In this study, the imaginary part of complex dielectric constants (ε′′) and dielectric loss tangent (tan σ) of benzene mercaptan, difurfuryl disulfide, and benzothiophene were characterized. The dipole moment, molecular configuration, and frontier molecular orbital energy of organic sulfur compounds were simulated and calculated under the different external energy fields. The migration law of mercaptan, sulfide, and thiophene in coal in microwave field were analyzed. The results show that the ε'′ and tan σ of benzothiophene slightly changed with the change in microwave frequency in the frequency range of 500–2500 MHz, and the microwave absorption properties are weaker than those of benzene mercaptan and difurfuryl disulfide. Therefore, difurfuryl disulfide and benzene mercaptan molecules are more active in the microwave field than benzothiophene. The sulfur components in benzene mercaptan and difurfuryl disulfide can dissociate in the form of small inorganic sulfur molecules of carbon sulfides and disulfides, respectively. After microwave irradiation, the relative content of mercaptan and thioether in coal was decreased, whereas the relative content of thiophene remained almost unchanged.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Microwave absorption properties and quantum chemistry of organic sulfur compounds in coal

Tao

Wang

et al. 2023

Asia-Pacific J Chem Eng

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“…In the field of microwave radiation of coal, microwave is heated in the form of coal sample as a whole, and the temperature and stress are concentrated. The internal of coal sample is dominated by compressive stress failure, and the external edge of coal sample is dominated by tensile stress failure [19]. After microwave irradiation, wave velocity and other physical and mechanical parameters of the specimen in different directions deteriorated to different degrees.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on mechanical damage characteristics of water-bearing tar-rich coal under microwave radiation

Yang

Shan

Chen

et al. 2023

Preprint

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As a recognized special resource, tar-rich coal can extract the country 's scarce oil and gas resources and generate semi-coke that can replace anthracite and coking coal. The tar-rich coal in northern Shaanxi is prominent, but due to the dense structure and high strength of tar-rich coal, it is easy to cause frequent dynamic disasters in coal mining. Therefore, the realization of pressure relief and disaster reduction has become the primary problem in mining tar-rich coal. There are many shortcomings in conventional pressure relief methods, so a new method of microwave weakening coal is proposed. Through different water saturation treatment of tar-rich coal samples, the longitudinal wave velocity degradation trend and surface crack expansion law of water-bearing coal after microwave irradiation were analyzed, and the strength softening characterization and energy evolution relationship under the combined action of microwave and water were studied. Fractal dimension and its internal correlation based on the equivalent side length-mass of coal sample fragments. The experimental results show that : (1) Under the same microwave radiation condition, with the increase of water saturation, the deterioration trend of physical and mechanical parameters such as longitudinal wave velocity and peak strength is obvious. (2) After microwave radiation, the uniaxial compression results show that the coal sample is damaged by load, there is still a high residual strength, the ratio of elastic energy to dissipation energy decreases, and the possibility of rockburst of coal sample decreases. The strength softening degree of coal specimen under the codegradation of microwave and water is the highest, followed by microwave and water. (3) The fractal dimension is inversely proportional to the moisture content and microwave radiation intensity, and the fractal dimension has a significant positive correlation with the peak intensity and longitudinal wave velocity. The mechanical damage law of water-bearing tar-rich coal under microwave action is revealed, which aims to solve the problem of weakening and reducing impact of hard coal on site to a certain extent, ensure the safety of working face and improve the mining efficiency of tar-rich coal. It provides basic theoretical support for microwave-assisted hydraulic fracturing technology and effective weakening measures for hard roof treatment.

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Loaded Failure Characteristics of Anthracite Derived from Microwave Irradiation: Acoustic Emission Evaluation

Gao,

Zhao,

Wang

et al. 2023

Rock Mech Rock Eng

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Dielectric anisotropy effects on the microwave-induced thermodynamic response of coal: Numerical simulations and experiments

Cited by 12 publications

References 54 publications

Microwave absorption properties and quantum chemistry of organic sulfur compounds in coal

Microwave absorption properties and quantum chemistry of organic sulfur compounds in coal

Experimental study on mechanical damage characteristics of water-bearing tar-rich coal under microwave radiation

Loaded Failure Characteristics of Anthracite Derived from Microwave Irradiation: Acoustic Emission Evaluation

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