高倍泡沫加速泄漏LNG扩散的有效性模拟试验

泡沫灭火剂在扑灭液体火灾中起到重要作用,关于低温液体蒸气云扩散控制的研究也逐渐得到应用。通过小尺寸模拟试验验证高倍泡沫加速泄漏LNG扩散的有效性,设计并进行了低温液体自然蒸发和高倍泡沫覆盖低温液体两个对照试验,测量了竖直方向上10个高度处的温度及装置整体质量,从而获取了低温液体蒸气到达泡沫层顶端时温度及蒸发速率的变化情况。结果表明,与未添加泡沫的情况对比,高倍泡沫的覆盖使泄漏低温液体在1 800 s内的蒸发量减少了6.4%,如果时间更长则减少的比例更多,且蒸发出的低温液体穿过泡沫层后蒸气温度可达0℃左右,而未添加泡沫时同等高度处蒸气温度为-75℃左右。0℃时,LNG蒸气密度已明显小于空气密度,此温度下LNG蒸气会迅速向上扩散,而不至在地表积聚,由此证明高倍泡沫能够加速泄漏低温液体蒸气向上扩散,减小了低温液体蒸气在地面积聚并引发火灾爆炸事故的可能性,从而证实了高倍泡沫加速泄漏LNG扩散的有效性。

Simulated experimental study for the effectiveness of the highly expandable foam via the accelerated leakage LNG dispersion

The paper is engaged in a simulated experimental study for the effectiveness of the highly expandable foam via the accelerated leakage LNG Dispersion.As a matter of fact,the foam extinguishing agent plays an important role in fighting against the liquid-resulted fire,which has also gradually been applied to the field of cryogenic liquid vapor cloud control.In hoping to study the effectiveness of such highly expandable foam,we have laid out a small simulation experiment to verify the effectiveness of the foam's leakage accelerate diffusion of LNG.For the purpose of comparison,we have designed two control experiments and carried out a so-called cryogenic liquid natural evaporation experiment.And,in contrast,we have also tested and measured the temperature changes at a variety of 10 heights in vertical direction with the quality change of the whole device intended to achieve the temperature of the cryogenic liquid vapor when it arrives at the top of the foam layer and the changes of the evaporation rate.In the said experiments,we have also done the other one with the high expansion foam covering cryogenic liquid.By observing the experimental Phenomena and comparing the data of the experiments with and without foam added,we have come to a conclusion that adding it has been proved possible to reduce the cryogenic liquid evaporation capacity by a rate of 6.4％ in a period of 1 800 seconds with the high expansion foam with the time extension and greater proportion reduction.Besides,the cryogenic liquid vapor temperature can be made so low as about 0 ℃ through the foam layer.Nevertheless,the steam temperature at the same height without foam added can be made to stay about-75 ℃.What is more,the LNG vapor density can be made to stay remarkably less than that of air at 0 ℃,whereas the LNG steam can be made spreading upwards promptly at such temperatures,with nothing being deposited on the ground surface.Thus,it can be concluded that the high expansion foam can actually be accelerated by way of cryogenic liquid leakage steam upward diffusion,and so can it be reduced by the accumulating the cryogenic liquid vapor on the ground,so as to reduce the probabilities of fire explosion accidents.Hence,it can be confirmed that high expansion foam can effectively accelerate the cryogenic liquid diffusion.