Thermal properties and microstructural evolution of coal spontaneous combustion

Pan, Rongkun; Liu, Cong; Chao, Jiangkun; Hu, Daimin; Jia, Hailin

doi:10.1016/j.energy.2022.125400

Cited by 63 publications

(11 citation statements)

References 18 publications

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“…Coal has long been the ballast stone for China’s energy security and a stabilizing agent that supports energy-structure adjustment and transformation development, and in 2022, China’s coal production reached its highest level. − However, with increase in coal mining, the reservoir characteristics of “high ground stress, high gas content, high temperature, and low permeability” have become more serious. − In addition, the extraction of coalbed methane (CBM) is becoming increasingly difficult, and gas disasters have become more dangerous. − Therefore, measures need to be taken to transform the properties of seams to enhance the extraction of methane and provide security for coal mines.…”

Section: Introductionmentioning

confidence: 99%

Construction of Macromolecular Structural Models of Coal and Simulation of Adsorption under Acidification

He,

Yuan,

et al. 2024

Ind. Eng. Chem. Res.

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We explored the influence of acidification on the structure, wettability, and adsorption capacity of coal based on Xray diffraction, water adsorption tests, elemental analysis, 13 C nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, isothermal adsorption tests, and molecular simulations. The results indicated that the silicate content in the experimental coal samples was high and the optimal acidification condition for improving wettability was 4% hydrofluoric acid with a 6 h reaction time. Under acidification, the aromatic structure in coal changed slightly, while the aliphatic structure and functional groups were significantly altered. In addition, the aliphatic chains were broken to form shorter chains, and the carbon structures changed from methylene and hypomethylene to methyl. Moreover, acidification removed nitrogen atoms and generated a greater number and variety of oxygen-containing groups. The macromolecular structural models of the coal samples and the acidified samples were constructed according to the above tests, and adsorption simulations were subsequently performed by using the models. In the CH 4 adsorption simulation, the adsorption capacity decreased after acidification, and the changing trend was highly consistent with the isothermal adsorption tests. In the simulation of the adsorption of H 2 O molecules and gas−water binary components, the macromolecular model of acidified coal exhibited better performance in absorbing H 2 O, and the improved wettability further inhibited its adsorption capacity for CH 4 . Our findings are crucial for exploring the mechanisms underlying the acid modification of wettability and adsorption capacity of coal at the microscopic level.

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Section: Introductionmentioning

confidence: 99%

Construction of Macromolecular Structural Models of Coal and Simulation of Adsorption under Acidification

He,

Yuan,

et al. 2024

Ind. Eng. Chem. Res.

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“…As an important energy source in the world, coal plays an important role in the chemical industry, steel, and power generation. − Coal spontaneous combustion, which occurs during coal mining, storage, and transportation, is considered one of the most dangerous natural disasters encountered in the coal industry. − To inhibit spontaneous combustion in coal mines, various methods have been proposed by scholars, including grouting, injection of inert gases, foams, inhibitors, and gels. − However, these techniques still suffer from many drawbacks, such as the gully phenomenon of grouting, the strict underground environmental conditions for inert gases, and the limited diffusion range of gels and inhibitors. − Therefore, development of efficient coal mine fire prevention and extinguishing technology is crucial for prevention and control of coal spontaneous combustion.…”

Section: Introductionmentioning

confidence: 99%

Inhibition Effect of Coal Spontaneous Combustion by Composite Inhibitory Foam Based on CaCl₂–Melatonin Inhibitor

Zhang,

Zhao,

Wang

et al. 2024

ACS Omega

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Inhibitory foam technology plays an important role in inhibiting coal spontaneous combustion. To enhance the stability and inhibitory performance of inhibitory foam for coal spontaneous combustion, a novel physicochemical composite inhibitor was developed in this work. CaCl2 was chosen as an inorganic salt physical inhibitor to compound with the chemical inhibitor melatonin (MLT) due to its corresponding good foam stability. When the mass ratio of CaCl2 to MLT was 4:1, the lowest CO release concentration of 7337.06 ppm at 200 °C was observed in the composite inhibitor-treated coal. Furthermore, the addition of 20 wt % of the composite inhibitor resulted in a foam half-life of 3067 min, which was 5.89 times longer than that of the water-based foam. In comparison with the water-based foam, the inhibitory foam based on 20 wt % CaCl2–MLT composite inhibitor exhibited more excellent foam stability, wetting ability, and inhibition performance. The release of CO at 200 °C was 7854.6 ppm, showing a reduction of 63.2% compared to the raw coal. Moreover, the composite inhibitory foam could significantly delay the onset of the characteristic temperature and reduce the weight change during the decomposition stage by 12.8%.

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“…Wen et al 9 and Xiao et al 10 experimentally assessed the spontaneous combustion characteristics of coal under different oxygen volume fractions, and analyzed the characteristic temperature, mass loss, thermal effect, and thermal reaction kinetic parameters of coal sample oxidation. Pan et al [11][12][13] carried out in-depth research on the thermal and microstructure characteristics of coal in the process of oxidation spontaneous combustion, and concluded that the thermal properties of coal spontaneous combustion have obvious segmental characteristics, which are not affected by metamorphism degree and heating rate, and the thermal dynamic balance is an important reason for the change of microstructure. In the oxidation process, the spatial arrangement of the molecular structure evolution of coal is reversible, and the -OH group is conducive to the oxidation of coal.…”

Section: Introductionmentioning

confidence: 99%

Dependence evaluation of factors influencing coal spontaneous ignition

Wu,

Yao,

Chen

et al. 2023

Energy Science & Engineering

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Coal spontaneous combustion is determined by a variety of factors. Testing can describe the changes incoal spontaneous combustion with various factors, however, the dependence of spontaneous combustion on various factors is unclear. Therefore, reliability theory was used to deduce the functional relationship of the dependence of coal spontaneous combustion on various factors, and construct a model algorithm for predicting the probability of occurrence of coal spontaneous combustion, which is adopted to evaluate and rank the degree of influence of various factors on coal spontaneous combustion. Effective prevention methods are proposed by strengthening the role of the most important factors. The results show that, by taking the duration of coal heating to 150°C as the measurement standard of coal spontaneous combustion, the duration of the initial stage of coal heating increases linearly with the increase of specific heat capacity, thermal conductivity, and moisture content of coal. With the increase of oxygen concentration, oxidation rate, and initial temperature of the coal, the duration of the initial stage of coal heating decreases exponentially. With the increase of gas flow seepage velocity in the coal body, the duration of the initial heating stage changes in a parabolic manner. At the same time, the probability of spontaneous combustion decreases exponentially with the increase of specific heat capacity and moisture content of the coal. The probability of coal spontaneous combustion increases linearly with the increase of coal thermal conductivity, oxygen concentration, gas seepage velocity, and rate of oxidation. The dependence of coal spontaneous combustion probability on different factors can be expressed as follows: coal temperature > gas seepage velocity > specific heat capacity > oxidation rate > oxygen concentration > moisture content > thermal conductivity.

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Thermal properties and microstructural evolution of coal spontaneous combustion

Cited by 63 publications

References 18 publications

Construction of Macromolecular Structural Models of Coal and Simulation of Adsorption under Acidification

Construction of Macromolecular Structural Models of Coal and Simulation of Adsorption under Acidification

Inhibition Effect of Coal Spontaneous Combustion by Composite Inhibitory Foam Based on CaCl₂–Melatonin Inhibitor

Dependence evaluation of factors influencing coal spontaneous ignition

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Thermal properties and microstructural evolution of coal spontaneous combustion

Cited by 63 publications

References 18 publications

Construction of Macromolecular Structural Models of Coal and Simulation of Adsorption under Acidification

Construction of Macromolecular Structural Models of Coal and Simulation of Adsorption under Acidification

Inhibition Effect of Coal Spontaneous Combustion by Composite Inhibitory Foam Based on CaCl2–Melatonin Inhibitor

Dependence evaluation of factors influencing coal spontaneous ignition

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Product

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Inhibition Effect of Coal Spontaneous Combustion by Composite Inhibitory Foam Based on CaCl₂–Melatonin Inhibitor