高倍泡沫抑制低温液体泄漏扩散试验研究

Experimental research on suppression of leakage diffusion of cryogenic liquid by high expansion foam

为提高液化天然气(LNG)接收站场的消防处理手段和应急处置能力,明确高倍泡沫抑制低温液体泄漏扩散的内在机制和环境影响,首先通过室内泡沫发生装置和小型风洞装置,试验研究高倍泡沫抑制液氮泄漏扩散的过程;然后采用控制变量法,分别测试不同环境风和热辐射条件下高倍泡沫的析液性能以及对低温液体蒸发速率的抑制效果。研究表明:在初始阶段泡沫的析液速率较快,随着泡沫体系内液体质量的不断减少,析液速率逐渐下降,泡沫的析液速率呈指数式下降趋势,而随着施加环境风和热辐射,析液速率提升;当高倍泡沫覆盖在液氮表面时,蒸发速率呈现动态变化趋势,且分为快速蒸发、稳定蒸发和快速下降等不同阶段;随着风速从0增加到3.5 m/s,热辐射强度从0增加到350 W/m 2,稳定阶段低温液体的蒸发速率呈线性增加趋势,最大平均蒸发速率分别增加了43.5%和69.9%,导致泡沫的抑制作用下降。

To improve the emergency management of the fire prevention and emergency response of the liquified natural gas(LNG)receiving station,and to clarify the essential mechanism and environmental effect of high expansion foam suppression on leakage and diffusion of cryogenic liquid,an experimental study of high expansion foam suppression on leakage and diffusion of liquid nitrogen through an indoor foam generator and wind tunnel device was conducted by control variable method.Then,the drainage behavior and suppression effect of high expansion foam on cryogenic liquid under different conditions between crosswinds and thermal radiations were also measured.The results show that at the initial stage,the drainage rate of foam is fast.The drainage rate of foam gradually decreases with the decrease of liquid quality in foam system,and the drainage rate of foam decreases exponentially.With the application of crosswinds and thermal radiations,the foam drainage rate rapidly increases.There are different stages of rapid increase,stable stage and rapid decline stage during the dynamic process of the evaporation rate for foam application on liquid nitrogen.The evaporation rate in stable stage shows a linear increase trend with a maximum value of the evaporation rate at 43.5%and 69.9%when the wind speeds increase from 0 to 3.5 m/s and thermal radiations increase from 0 to 350 W/m 2,resulting in a decrease effect of high expansion foam.