正压密封方法数值模拟及其在矿井防灭火中的应用

Numerical simulation of positive pressure sealing method and its application in coal mine fire control

为控制采空区火灾和防止有毒有害气体外泄,基于矿井空气流动理论和均压防灭火方法,建立气室注氮正压控制密闭漏风数值模型。分析气室内氮气正压对采空区密闭漏风行为的控制规律,并以恒大煤矿2132工作面采空区火灾控制为实例进行验证。实例结果表明,在气室内连续注入的氮气的相对正压作用下,通风巷道向采空区漏风的速率迅速减小,并最终停止和反向,形成由气室向通风巷道微量漏氮状态;当采空区抽采负压在-300 Pa,瓦斯流量为30 m3/min,瓦斯体积分数为70%时,保持气室注氮流量0.2 m3/min、正压15 Pa,回风巷处采空区内O2体积分数在1天内降至5%以下,C2H2在3日内消失,C2H4在15日内消失,CO在26日内消失,温度在35日后降至30℃以下,采空区火灾得到控制。

To control goaf fire and harmful gas leakage,based on mine air flow theory and pressure balance fire control method,a numerical model was built for goaf sealing wall air leakage controlled by positive pressure in chamber injected with nitrogen. Then behavior of the air leakage through goaf sealing wall under the chamber nitrogen positive pressure was numerically analyzed. Finally,application effect of the positive pressure sealing method was verified by practice of fire control at the working face 2132 of Hengda coal mine. The results show that under the influence of the relative positive pressure of continuous injected nitrogen,the air leakage from ventilation roadway to goaf rapidly decreases,then stops sand reverses,and a state begins to exist in which the chamber nitrogen slightly leaks out to the ventilation roadway,and that under the condition that the goaf gas drainage pressure is negative 300 Pa,the gas drainage flow is30 m^3/ min and the CH4 volume fraction is 70%,the nitrogen injection flow is kept at 0. 2 m^3/ min,and the nitrogen positive pressure is kept at 15 Pa,the O2 reduces below 5% within 1 day,C2H2 disappears within 3 days,C2H4 disappears within 15 days,CO disappears within 26 days,and the temperature drops to 30 ℃ below within 35 days,and the goaf fire is successfully controlled.