采空区开区注氮灭火温度场冷却过程的数值模拟

为研究开区注氮条件下,采空区遗煤自燃被抑制和熄灭作用复杂力学过程(原理),由非均质多孔介质中的渗流连续性方程、气体弥散方程和综合传热方程的联立,建立了注氮采空区煤自燃的非定常数值模型。结合实例,用迎风格式有限元方法求解。计算在不同情况下采空区自燃高温点熄灭过程,以图形方式给出了采空区的漏风流态、氮气流态,描绘灭火降温过程中,采空区氧、CO和温度分布的动态变化过程。提出了对自燃早期火灾施行开区注氮灭火的方法和适用的判定准则。理论计算得到开区注氮灭火分为两个阶段过程,即原火源熄灭和新自燃氧化区形成并自燃。指出实施开区注氮灭火应准确把握注氮时机和防止新自燃氧化区形成的工作面开采推进时机;并配合降低漏风措施条件下进行注氮。

Numerical Simulation of Rise Process in Temperature Field Causedby Nitrogen Injection into Goaf

Based on seepage equation of air leakage, seepage flow-diffusion-consumption equation of oxygen concentration and heat transfer equation, a non-steady numerical model of spontaneous combustion in goaf is established; these equations are combined and solved by windward finite element based numerical simulation. Referring to a practical example, air leakage seepage flow, oxygen concentration distribution, temperature distribution in goaf and the accelerating variation process of them with time are described theoretically. The quantitative relationship between the oxygen consumption of losing coal during spontaneous combustion and temperature rise is discussed emphatically. It could be conclude that high temperature zone appears usually at the inlet air side, and boundary air leakage has a little influence on it. It is pointed out that the traditional tri-zone division of the cooled zone, spontaneous combustion zone and suffocating zone of goaf is obscure, while the mode in the paper can solve more exactly the spontaneous combustion problem.