超细水雾抑制受限空间煤燃烧的试验研究

Role of ultra-fine mist spray technology in restraining coal-mine combustion in a limited space

为了将超细水雾技术应用于抑制井下采空区遗煤自燃,通过搭建超细水雾抑制受限空间煤燃烧的小尺寸试验台,研究了超细水雾抑制受限空间煤燃烧的有效性及影响因素。研究表明,施加超细水雾后,煤的热释放速率下降速度和受限空间O_2体积分数的下降速度增大,CO_2的生成量逐渐减少,而CO的生成量在短时间内急剧增大后又减少,最终趋于稳定。这说明超细水雾可以有效降低煤的热释放速率和组分生成速率。超细水雾抑制煤燃烧的效果依赖于其雾通量、开始施加时刻和施加时间等因素。雾通量充足时,在煤燃烧初期施加超细水雾,熄灭煤火焰的效果较好,待煤充分燃烧时,再施加超细水雾,熄灭煤火焰的时间延长;雾通量不足时,超细水雾无法抑制煤的燃烧。对充分燃烧的煤施加超细水雾的时间越长,熄灭煤火焰的效果越好。

Based on the study of the environment-friendly and highly- efficient uhra-fine water mist spray technology, this paper is aimed to set up an experimental system for putting out the spontaneous coalmine fire. The experimental system here mentioned is mainly composed of a limited space, an ultra-fine mist fire-extinguishing equipment, an electronic weighing unit, a smoke analysis unit and a temperature regulation unit. In order to get the heat-release and the component-generating rate, the experiment can be done in the following procedures. At first, the coal sample was heated enough to produce open-fire flame in the furnace, then it was put into a burning container which was above the electronic scale. A few seconds later, the ultra-fine mist spray unit, the smoke analysis unit, and the temperature-regulating unit would be made to start, so that the mass loss rate and componentsenerating rate unit in the confined space may start with its recordings. And now the mass loss rate unit can now be convened into heat releasing rate through the related formula. The experiments we have done help us to find that with the decrease of the heat release rate and the increase of O2 volume, the production of CO2 tends to drop gradually, while the production of CO tends to increase dramatically in a short moment and then drop down, and finally, tends to get stable after discharging the ultra-fine mist. It means that the ultra-fine mist can effectively reduce the heat release of the coal and components-generating rate. It was also found that the restraining effect relies much on the mist flux, the discharge-starting moment, the discharge length of time, etc. Though plentiful mist flux is important for extinguishing the coal fire, the ultra-fine water mist still can not restrain the combustion of coal if the mist flux is not strong enough. With the same mist flux and discharging time, earlier discharging before sufficient coal combustion indicates a better effect than when the coal combustion goes sufficiently as compared to the mere discharge. For on the condition of sufficient coal combustion, when the mist flux and beginning discharging moment were fixed, the more the discharging time, the more it is likely to extinguish the coal flame .