基于CFD的半封闭空间内LNG泄漏后果研究

Study on consequence of LNG leakage in semi-confined space based on CFD

为定量分析半封闭空间内液化天然气（LNG）泄漏后果,利用计算流体力学（CFD）软件FLUENT,对不同条件下的＂冷箱＂内LNG泄漏后扩散与爆炸过程进行了模拟。结果表明：无论通风与否,危险区域（甲烷体积分数为5%-15%）一直存在,但通风时该区域比无通风时小;LNG泄漏后会导致箱内温度降低,且泄漏量越大温度下降越低,但通风在一定程度上能减小温降;当危险区域最大时,发生爆炸产生的超压最大,对于泄漏量小的情况,通风能减小爆炸压力;障碍物的存在会增大爆炸压力,研究中的最大爆炸超压为158 k Pa,可对设备与人员造成严重危害,故在设计＂冷箱＂时须提出相应的强度要求。研究方法与结果对于与＂冷箱＂类似的受限空间安全设计与风险评估有指导意义。

To quantitatively analyze the consequence of LNG leakage in semi- confined space,the diffusion and explosion after the leakage of LNG in a ＂ cold box＂ under different conditions were simulated by using the CFD software FLUENT. The results showed that the dangerous area with methane content of 5%- 15% by volume fraction always exists whether there is ventilation or not,but this area with ventilation is smaller than that without ventilation. The leakage of LNG will cause the temperature in the box decrease,the larger the leakage amount,the lower the temperature decrease,but the ventilation can reduce the temperature decrease to a certain extent. The biggest dangerous area produces the maximum explosion overpressure,and the ventilation can reduce the explosion pressure when the leakage amount is small. The existence of obstacles will increase the explosion pressure,the maximum explosion overpressure in this study was 158 k Pa,which can cause serious hazard to equipments and personnel,so the corresponding requirement of strength should be put forward when designing ＂ cold box＂. It has guiding significance for safety design and risk assessment of confined space similar to ＂ cold box＂.