Abstract:

In order to study the influence of ignition delay time on the characteristics of CO₂-ultra-fine water mist suppression of gas/coal dust explosion, different concentrations of ultra-fine water mist and CO₂ were introduced into 20 L ball through a self-made ultra-fine water mist generator, and the explosion pressure, flame propagation velocity, flame structure and explosion flow field turbulence images of gas/coal dust under different ignition delay time were obtained. The research results show that compared with single explosion suppression, under the action of CO₂-ultra-fine water mist, with the extension of ignition delay time and the increase of water mist concentration, the explosion intensity of gas/coal dust is weakened and the flame propagation speed is reduced. For 10%CO₂ and 306 g/m³ ultra-fine water mist, the maximum explosion pressure and pressure rise rate at 1500 ms ignition delay are reduced by 6.79% and 16.14% respectively compared with those without water mist, and the arrival time of maximum explosion pressure is extended by 24.47%. Under 10%CO₂ and 204 g/m³ ultra-fine water mist, the maximum explosion pressure and average flame speed at 2000 ms ignition delay are reduced by 5.22% and 37.5% respectively compared with 1000 ms ignition delay, and the arrival time of maximum explosion pressure is extended by 24.66%. It can be seen from the explosion flame schlieren image and PIV test that with the increase of water mist concentration and the extension of ignition delay time, the flame brightness decreases and sinks, and the motion state of coal dust particles in the flame changes from centripetal motion to rotational motion. This is because the initial intensity of gas explosion under the action of CO₂ inerting decreases, while the concentration of water mist increases, the energy consumed by water mist endothermic evaporation increases during the explosion process, and the generated water vapor dilutes the oxygen concentration around the flame, further inhibiting the explosion reaction. Prolonging the ignition delay time strengthens the influence of water mist on the movement of pulverized coal, reduces the agglomeration and dispersion of coal dust, weakens the turbulent effect of coal dust cloud, suppresses the combustion and explosion of coal dust clouds, and finally reduces the explosion intensity of gas/coal dust. The research results provide technical guidance for the determination of control parameters of gas/coal dust explosion suppression by gas-liquid two-phase detonation inhibitor.

Key words: ignition delay time, CO₂, ultra-fine water mist, gas/coal dust, explosion suppression

摘要：

利用20 L球爆炸实验平台，系统研究了不同点火延迟时间对CO₂-超细水雾抑制瓦斯/煤尘爆炸特性的影响。结果表明：相比单一抑爆，在CO₂-超细水雾作用下，随着点火延迟时间延长和水雾浓度增大，瓦斯/煤尘爆炸强度削弱，火焰传播速度降低，火焰亮度降低且出现下沉现象，火焰内部煤尘粒子运动状态由向心运动向旋转运动转换。10%CO₂、306 g/m³超细水雾时，在1500 ms点火延迟时的最大爆炸压力和最大压力上升速率比无水雾时分别降低了6.79%和16.14%，最大爆炸压力来临时间延长了24.47%；10%CO₂、204 g/m³超细水雾下，在2000 ms点火延迟时的最大爆炸压力和火焰平均速度比1000 ms点火延迟时分别降低了5.22%和37.5%，最大爆炸压力来临时间延长24.66%。研究结果为气液两相抑爆剂抑制瓦斯/煤尘爆炸控制参数的确定提供了技术指导。

关键词: 点火延迟时间, CO₂, 超细水雾, 瓦斯/煤尘, 抑爆