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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。
Foam extinguishing agents play an important role in extinguishing liquid fires and research on the control of cryogenic liquid vapor cloud diffusion has also been gradually applied. Through the small-scale simulation test to verify the effectiveness of high-power foams in accelerating the diffusion of leaked LNG, two control experiments were designed and carried out, including natural evaporation of cryogenic liquid and high-temperature foam covered cryogenic liquid. The temperature at 10 vertical positions and the whole device Quality, which was obtained when the cryogenic liquid vapor reaches the top of the foam layer temperature and evaporation rate changes. The results show that compared with the case of no added foam, the high foam coverage reduced the leakage of cryogenic liquid by 6.4% within 1 800 s, and decreased more if the time was longer, and the evaporated cryogenic liquid After the foam layer vapor temperature up to about 0 ℃, without adding foam at the same height when the vapor temperature is about -75 ℃. 0 ℃, LNG vapor density has been significantly less than the air density, LNG vapor will rapidly spread upward at this temperature, not to accumulate on the surface, which proves that the high-speed foam can accelerate the leakage of low temperature liquid vapor up diffusion, reducing the low temperature liquid vapor The possibility of accumulating on the ground and triggering a fire and explosion event confirms the effectiveness of high power foams in accelerating the diffusion of leaked LNG.