采空区遗煤自燃升温过程的数值模型及其应用

基于漏风渗流方程、氧浓度渗流-扩散-消耗方程和传热方程,建立了采空区自然发火非定常数值模型,并用迎风格式的有限元方法联立求解.结合实例,从理论上描绘了采空区漏风渗流、氧浓度分布和温度分布,以及它们随时间的加速变化过程,同时给出自燃的附产物CO的分布情况,重点给出了遗煤的自燃耗氧与升温的量化关系.结果表明,通常情况下采空区高温区偏在入风一侧,边界漏风对高温区有一定影响.与传统的采空区冷却带、自燃带和窒息带的三带划分相比,该模型能对自然发火问题给出更准确的解.模拟的自燃升温是加速的过程,同基于实验分析和实际观测得到的规律基本一致.

Numeral simulation model and application of temperature rise process caused by natural burn of lossed coal in goaf

The present paper aims to introduce the author's visual numerical simulation of temperature-rising process due to the spontaneous combustion in goaf. The simulation model has been established on the basis of the seepage equation of air leakage, the seepage flow-diffusion-consumption equation of oxygen concentration and heat transfer equation, as well as the non-steady numerical model of spontaneous combustion in goaf, all of which are combined and solved by the windward finite element based numerical simulation. As an example, air leakage seepage flow, oxygen concentration distribution, temperature distribution in goaf and their accelerated variation process with time are discussed first theoretically, and then quantitatively and emphatically as to the relation between the oxygen consumption of the losing coal during the spontaneous combustion and temperature rising. Thus, it can be concluded that usually high temperature zone appears at the inlet air side, where boundary air leakage has little influence. Therefore, it is necessary to point out that the traditional tri-zone division is ambiguous as to the cooled zone, the spontaneous combustion zone and the suffocating zone, while the mode presented in the paper will enable to solve the spontaneous combustion problem more ideally. The simulated result shows that the temperature rise during spontaneous combustion is an accelerated process and the conclusion would accord with the law obtained by the experimental analysis and actual observation.