防护堤对LNG扩散的抑制作用

Inhibitory effect of fending groin on LNG diffusion

除有效容积外,设置高度也是LNG储罐区防护堤设计的关键参数。采用数值模拟技术,对半地下LNG罐池,在不同防护堤高度作用下的LNG液池扩展和LNG低温蒸气扩散行为进行数值模拟,对比分析防护堤高度和罐池底面积对LNG低温蒸气扩散速度、可燃气云隔离距离和云团尺寸的影响。结果表明:增加防护堤高度可以有效减小LNG泄漏后产生的可燃气云体积、尺寸及最大扩散距离,但同时延长了可燃气云的滞留时间,增加燃爆和窒息发生的危险。对于同一种罐池,在液池充分扩展前,可燃气云最大扩散距离与罐池底面积成正比。对于LNG储罐区,可通过提升罐池的防护堤高度减小LNG扩散的安全距离。

In addition to effective capacity, height is a key parameter to design the fending groin for LNG tankfarrn. The liquid pool extension and diffusion behavior in low temperature of semi-underground LNG tank pool are simulated by numerical simulation technique. The impacts of the height of fending groin and the basal area of tank pool on the vapor diffusion velocity at low temperature, the isolation distance of combustible gas clouds and the size of cloud cluster are compared and analyzed. Results have shown that higher fending groin can effectively reduce the volume, size and maximum diffusion distance of combustible gas cloud produced after the LNG leakage while it prolongs the residence time of flammable gas clouds and increases the risk of combustion and suffocation. For the same kind of tank pool, the maximum diffusion distance of the combustible gas cloud is proportional to the basal area of tank pool before the full extension of liquid pool. For the LNG tank farm, it can reduce the safe distance of LNG diffusion by increasing the fending groin height of tank pool.