A fully coupled hydro-thermo-mechanical model for the spontaneous combustion of underground coal seams
A fully coupled hydro-thermo-mechanical model for the spontaneous combustion of underground coal seams
复制标题
DOI：
10.1016/j.fuel.2014.02.023
复制
发表时间：
2014-06-01
期刊：
影响因子：
7.4
通讯作者：
Gao, Feng
中科院分区：
文献类型：
--
作者：
Xia, Tongqiang;Zhou, Fubao;Gao, Feng
地下煤层自燃过程涉及多孔煤介质中地质力学效应、氧输运和能量输运的复杂相互作用。以往的研究通常忽略了由于煤的自热引起的气体和煤的膨胀等热力学效应，并且没有将这些复杂的相互作用完全实现到他们的模拟中。在本研究中，建立了煤的力学变形、气体流动和输运以及热输运的完全耦合模型，并通过一套煤的性质模型和状态方程定义了它们之间复杂的相互作用。包括(1)煤孔隙度模型；(2)煤层渗透率模型；(3)气体状态方程；(4)自热模式。应用该模型定量预测了东滩煤矿地下采空区巷道自燃的时间和位置，结果与现场实测结果吻合较好。此外，通过与其他模型的对比，发现煤的自热过程中存在由气体热膨胀和随后的气体压力梯度增大引起的显著的自加速加热效应[图形]。利用验证的模型，获得了煤渗透率、压差、耗氧速率和煤氧化反应热等外在因素和内在因素对采空区自热敏感性的影响，发现自热速率和气速与上述因素呈正相关，呈“s”型上升趋势，而氧浓度呈“s”型下降趋势。模拟结果可以为如何控制变量或参数以延缓或抑制多孔煤介质自燃提供一些建议。(C) 2014 Elsevier Ltd.版权所有。
The spontaneous combustion of underground coal seams involves complex interactions between geomechanical effects, oxygen transport and flow, and energy transport in the porous coal media. Prior studies normally ignore the thermo-mechanical effects such as gas and coal expansion due to the self-heating of coal, and have not implemented these complex interactions fully into their simulations. In this study, a fully coupled model of coal mechanical deformation, gas flow and transport, and heat transport is developed and their complex interactions are defined through a suite of coal property models and equation-of-states. These include (1) coal porosity model; (2) coal permeability model; (3) gas equation-of-state; and (4) self-heating model.Applying the model to quantitatively predict the time and locations of spontaneous combustion of underground gob-side entry in the Dongtan coal mine, the results are in good agreement with the in situ measurements. Besides, a significant self-accelerating-heating effect induced by the gas thermal expansion and subsequent gas pressure gradient increase is found in the self-heating process of coal[GRAPHICS]through the comparison results from our model with other models. Furthermore, the self-heating susceptibilities of gob-side entry associated with extrinsic and intrinsic factors, incorporating coal permeability, pressure difference, oxygen-consumption rate, and reaction heat of coal oxidation, are gained insight using the verified model, which suggests the self-heating rate and gas velocity are positively correlated with above factors showing "S-type" upward trends, whereas the oxygen concentration has an "S-type" downward trend. The simulated results can provide some suggestions as to how to control the variables or parameters to retard or suppress the spontaneous combustion of porous coal media. (C) 2014 Elsevier Ltd. All rights reserved.