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

Abstract

Coal and gas outburst is a dynamic phenomenon with violent eruptions of coal and gas from the working coal seam. It has been proved that the rapid desorption within a short period is necessary for the occurrence of an outburst. Due to limitation of the present test condition, gas desorption characterization for the first 60 s has not been researched sufficiently. In the present study, an experimental apparatus with the ability of high-frequency data collection was developed. Initial desorption characterization of methane and carbon dioxide in coal was experimentally studied. Both the initial desorption characterization of methane and carbon dioxide were experimentally studied with different equilibrium pressures. The desorbed gas pressure was measured at desorption time phase of 0-10 and 45-60 s, besides the initial amount of desorbed gas and initial diffusion velocity of coal gas were calculated to assess their risk of outburst. The results show that the gas pressure for both methane and carbon dioxide increases sharply in the initial time and then levels off, and the total amount of desorbed gas increases with the increasing desorption time. Although the amount of desorption methane is slightly larger than that of carbon dioxide at the beginning, the total amount of desorbed carbon dioxide is significantly larger than that of methane at the desorption process. Therefore, it can be concluded that the coal and carbon dioxide outburst is more dangerous than the coal and methane outburst based on the obtained experimental results.

Determination of initial velocity of gas diffusion under temperature control

“…The experiment was carried out strictly according to the technical standard of AQ 1080-2009 (Liang et al, 2018). In order to accurately describe the process of the experiment, this paper makes a schematic diagram of the determination system, as shown in Figure 4.…”

“…The initial velocity of gas diffusion of coal is an index that indicates how quickly the coal containing gas changes from adsorption state to free state under the condition of complete exposure. The greater the initial velocity of gas diffusion, the stronger the initial gas release capacity of coal body, and the greater the outburst risk of coal seam (Liu and Wang, 2013;Liang et al, 2018;Sun, 2018). This index has been used as one of the indexes to judge the danger degree of coal and gas outburst in most countries in the world, and has been widely used (AQ1080-2009(AQ1080- , 2009Wang and Shi, 1991;Lu, 1992).…”

Orthogonal Experimental Study on Multifactor Conditions for Gas Desorption in Coal

“…erefore, the gas desorption performance of coal was more profound. Studies have shown that as the gas adsorption pressure is increased, the initial velocity of coal gas desorption is signi cantly increased [32]. e corresponding cumulative gas desorption amount is greater for the same amount of time, and a higher gas pressure promotes the gas desorption of coal.…”

Data Mining Technology and Its Applications in Coal and Gas Outburst Prediction

“…The single-index method can easily predict coal and gas outbursts; however, its prediction accuracy is poor, and the critical value of the prediction index is difficult to determine. In each mine investigated, the most commonly used prediction methods are the number of drilling cuttings [16], initial gas emissions [17], initial gas desorption characteristics [15], debris index [18], and gas desorption index [19]. The outburst risk can be determined by collecting and comparing the corresponding indices during drilling operations.…”