加大加强通风量对防止煤矿瓦斯爆炸的副作用

Negative influence due to increased air flow of ventilation on gas explosion prevention in coal mines

分析产生瓦斯爆炸的基本条件,指出在绝对瓦斯涌出量为5～75m3/min或更大的轻度瓦斯突出的异常情况下,风筒送入的风与突出的瓦斯混合,会在较长巷道内形成大量的瓦斯浓度处于爆炸上限与下限之间的可爆混气。风量越大,形成的可爆混气体积越大,如400m3/min的风量在2min内就可形成≥842m3的可爆混气。遇火源可发生强烈的爆炸甚至爆轰,造成较大的伤亡甚至整个矿井内大部分人员死亡。这表明,加大加强的风量对防止煤矿瓦斯爆炸起副(反)作用。这种副作用已在试验巷道用天然气爆炸试验中得到证明。目前煤炭界采取的各种措施不能有效地消除加大加强风量引起的副(反)作用。提出了2种消除副作用的措施,即瓦斯传感器断电与复电方法和抽吸方法,并经试验证明是有效的。

This paper is inclined to report the authors＇ investigation and research of negative influence due to the increased air flow of ventilation in the gas explosion prevention in coal mines. As is known, there has been existing a tendency of increasing the air flow ventilation in the coalmining tunnels over the past years, however, mining accidents and explosions fail to be made reduced. In our investigation, it was found that the air flow ventilation for some high gas mines had been increased to 400 m^3/min. The reason for so doing is that it was believed that the bigger the air flow of ventilation, the safer the coal excavation is. It was also thought that the gas explosion can be prevented by increasing the gas concentration of the monitor equipment. In China, though the death roll due to the mining explosion decreased in 2005, the rate of serious mining accidents remains high with over 100 death cases listed, Actually the accide,ts took place 15 times as often as from 1949 to 2000. The above facts prove that increased ventilation and more tight management and regulation fail to stop or reduce serious gas explosions. The research of this paper indicates that the air flow from the air feed pipe mixed with the gas ejected from the coal layer, is potential to lead a massive explosive mixture with the gas concentration between explosive lower limit and explosive higher limit under the condition of gas ejection flow of 5-75 m^3/min or more. Therefore, with the gas mixture volume increased in the ventilation, the air flow of 400 m^3/min is likely to form explosive mixture as high as 842 m^3. If a source ignites an explosion gas-air mixture, the serious gas explosion, even detonation can take place in any coal-mining tunnels. The above study results show that the stronger ventilation can have negative effect on preventing gas explosion, This negative effect has been proven by the explosion tests performed in ＂experiment tunnel＂ of 2.5 m height 3.1 m width and 20 m length. Therefore, the authors＇ conclusion is that the present explosion prevention measures go contrary to the desire and goal to eliminate the coahnine disasters. Rather, two measures should be taken to eliminate such negative effects, which have been put forward by the author in the last part of the paper.