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Rapid gas desorption and its impact on gas-coal outbursts as two-phase flows
Process Safety and Environmental Protection ( IF 6.9 ) Pub Date : 2021-04-29 , DOI: 10.1016/j.psep.2021.04.042
Aitao Zhou , Meng Zhang , Kai Wang , Derek Elsworth , Nan Deng , Jiaying Hu

Coal and gas outbursts are a violent release of energy in part driven by rapidly desorbing gas from the fragmenting coal. We present a coupled two-phase model of coal and gas outbursts to define the timing, rate and magnitude of gas desorption and its contribution to the resulting energetics. The model involves a fragmenting ejection of the outburst from an overpressurized coal that retreats omnidirectionally from a point and develops a deepening crater. This model is applied to represents both experiments and in situ observations. These results indicate that the outburst is initially driven by free gas before desorbing gas rate exceeds this free gas liberation rate early into the outburst (at ∼17 s in our model). The cumulative mass of desorbed gas only exceeds the free gas later into the event at approximately double this duration (at ∼29 s in our model). During the outburst, ∼55 % of the expansion energy is contributed by desorbing gas. Using the initial gas emission rates for both non-tectonic and tectonic coals defines a power-law relationship between the initial gas desorption rate and the desorption gas contribution (∼14 %–92 %), indicating that the desorbing gas plays a decisive role in outburst development. Furthermore, taking the gas emission model as a boundary conditions for numerical simulations, the gas pressure potential energy (GPPE) released in the first millisecond at the maximum gas emission rate is derived to characterize its effects on the dynamic characteristics of the outburst two-phase flow. The maximum energy release intensity considering gas desorption is ∼5 times that without gas desorption for non-tectonic coal. For tectonic (mylonitized) coals the energy release is a further ∼4 times greater than that of non-tectonic coals. This paper presents a novel quantitative study defining the role of gas desorption in outbursts and contributes to the understanding of causal mechanisms and precursory phenomena preceding catastrophic outbursts.



中文翻译:

两相流快速瓦斯解吸及其对瓦斯突出的影响

煤与瓦斯突出是能量的猛烈释放,部分原因是从破碎的煤中快速解吸瓦斯。我们提出了一个煤与瓦斯突出的耦合两阶段模型,以定义瓦斯解吸的时间,速率和幅度及其对产生的能量的贡献。该模型涉及从超压煤中喷出的碎屑碎片,该碎屑从一个点全方向撤退并形成一个加深的火山口。该模型适用于代表实验和现场观察。这些结果表明,在解吸气速率超过该游离气体释放速率之前,游离气体首先驱使了该突出气体进入到突出物中(在我们的模型中为约17 s)。解吸气体的累积质量仅在此事件的大约两倍(在我们的模型中约为29 s)之后才超过事件之后的游离气体。在突出过程中,约55%的膨胀能来自气体的解吸作用。使用非构造煤和构造煤的初始瓦斯排放率定义了初始瓦斯解吸率与解吸气贡献率之间的幂律关系(〜14%–92%),这表明解吸气在煤中起着决定性的作用。爆发发展。此外,以气体排放模型为数值模拟的边界条件,推导了在第一毫秒以最大气体排放速率释放的气压势能(GPPE),以表征其对突出两相动力特性的影响。流。对于非构造煤,考虑到气体解吸的最大能量释放强度约为不进行气体解吸的5倍。对于构造性(mylonitized)煤,能量释放比非构造性煤高约4倍。本文提出了一种新颖的定量研究,该研究定义了瓦斯解吸在突出中的作用,并有助于理解灾难性突出之前的原因机理和先兆现象。

更新日期:2021-05-03
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