Influence rules and mechanisms of mechanical vibration at different frequencies on dynamic process of gas diffusion from coal particles

Abstract

To study the influence of vibration on gas desorption and diffusion in particle coal, gas desorption experiments on soft coal with outburst risk under different frequency vibrations were carried out by using a self-designed gas adsorption and desorption platform under vibration conditions, and the influence of different frequency vibrations on the diffusion kinetic parameters was quantitatively analyzed by using a dynamic diffusion coefficient model. The influence mechanism of vibration on gas desorption and diffusion in coal was further analyzed from the three aspects of gas molecules, energy conversion and pore structure through theoretical analysis and mercury injection experiments. The results showed that with increasing vibration frequency, the gas desorption of the coal samples first increases and then decreases. The initial diffusion coefficient of gas in the coal samples increases linearly with increasing vibration frequency, but the attenuation coefficient of the diffusion coefficient decreases first and then increases with increasing vibration frequency. The "throwing effect" and thermal effect of vibration on the gas molecules are both conducive to the desorption of gas molecules. In addition, vibration causes changes in the pore structure in coal, increasing gas diffusion paths and reducing diffusion resistance.

Study on the gas outburst control effect of goaf on the neighboring working face: Case study of Pingmei No.4 Mine

“…17 From the free surface to the inside, it is pressure unloading zone, stress concentration zone, and original rock stress zone in order, and the risk of coal outburst within the pressure relief zone has been eliminated. [18][19][20][21] Zhang et al 22 studied the coal pillar failure mechanism; the results indicated that the coal pillar can be divided into broken zone, stable zone, and collapsed zone, in which the stabilized zone accounts for one-third of the coal pillar width and plays a decisive role in coal pillar failure. Shi et al 23 investigated the movement law, the failure mechanism and the fracture evolution law of goaf-side entry driving in thick coal seams through experiments and numerical simulations.…”

“…Mining pressure theory shows that, under the influence of mining operation, the roof stress will be redistributed 17 . From the free surface to the inside, it is pressure unloading zone, stress concentration zone, and original rock stress zone in order, and the risk of coal outburst within the pressure relief zone has been eliminated 18–21 . Zhang et al 22 studied the coal pillar failure mechanism; the results indicated that the coal pillar can be divided into broken zone, stable zone, and collapsed zone, in which the stabilized zone accounts for one‐third of the coal pillar width and plays a decisive role in coal pillar failure.…”

Natural Frequency of Coal: Mathematical Model, Test, and Analysis on Influencing Factors

“…In terms of gas desorption excited by vibration wave, Chen et al [18,19] studied the influence of vibration on gas desorption diffusion in granular coal and drew the following conclusions: (1) With the increase of vibration frequency, gas desorption of coal samples first increased and then decreased. (2) Mechanical vibration could generate shear force in adsorbed gas to promote its desorption.…”