Constitutive model for methane desorption and diffusion based on pore structure differences between soft and hard coal

Dynamic Characterization during Gas Initial Desorption of Coal Particles and Its Influence on the Initiation of Coal and Gas Outbursts

“…Therefore, between the two types of coals, Equation ( 2) is more likely to be met for the TD coal with initial failure under the same gas pressure and the same degree of damage, easily leading to the spallation of coal mass. The conditions leading to the instability of spallation coal mass are shown in Equation (3), and an outburst occurrence depends on whether the local gas pressure in the large crack can meet the instability conditions. Figures 6 and 7 indicate that the mass flow rate and initial desorption rate of gas of the TD coal are approximately two times of those of the PU coal mass.…”

“…The law of gas desorption in coal particles has always been the one breakthrough point to explore the issues of efficient coal-bed methane recovery and gas dynamic disaster prevention [1][2][3][4][5]. For the mechanism of gas dynamic disasters such as outburst, as an outburst process only takes a few ~tens of seconds with an average time of 20 s [6], the law of gas initial desorption in coal particles is a key point that needs to be explored.…”

“…At present, more attention has been paid to the evolution characterization of desorption rate and capacity and the establishment of theoretical models in the gas initial desorption process of coal particles [3,4,[10][11][12][13][14][15]. In the view of the fact that the outbursts mainly occur in the TD coal with low mechanical strength, the research shows that the capacity of gas desorption of the TD coal is better than the PU coal [16].…”

Calculation Model and Rapid Estimation Method for Coal Seam Gas Content

“…Li and Yang [19] calculated and compared the gas loss in the sampling process using the graphic method and least squares method. The "Direct Gas Content Measurement Device (DGC)" [20][21][22][23][24][25][26][27], which was developed based on an empirical equation, can determine the gas content of coal. The calculation of the gas content is based on the law of gas desorption.…”

Desorption characterization of methane and carbon dioxide in coal and its influence on outburst prediction

“…The coal and gas outburst is closely related to the coalbed gas reserved in the coal. Coalbed gas is an associated product in the coal formation process (Tahmasebi et al., 2012), which is deposited in coal seam in several forms: adsorbed in the pores surface of the coal, as part of the coal molecular structure, existing in the fissures and larger pores as free gas, and dissolved in the water (Liu et al., 2018; Zarębska and Ceglarska-Stefańska, 2008; Zou and Lin, 2018). The adsorbed and free gas take up the most of coal bed gas, which dominates the occurrence of coal and gas outburst.…”