Abstract:

Before filling the liquefied natural gas(LNG)into the storage tank,a pre-cooling operation is needed to avoid the rapid dropping of temperature.In the present study,a numerical model of the pre-cooling of a LNG storage tank is presented in this paper.The heat and mass transfer during the pre-cooling process in the storage tank and the thermal conduction in the tank walls are taken into consideration in the current model.The simulation results show that the LNG droplets cannot cover the whole tank and there exists a maximum spray region.During the pre-cooling,the cool-down rate of the tank mainly depends on the LNG flow rate.The tank bottom part shows larger cool-down rate than the side wall.The maximum cool-down rate takes place at the center of the tank bottom.Due to backflow at the tank center,the wall temperature of this part will not decrease monotonically.

Key words: natural gas, vaporization, numerical simulation, storage tank, pre-cooling, spray

摘要：

建立了液化天然气(LNG)储罐喷淋预冷过程的流动传热与传质模型,对储罐内热物理场和储罐壁面温度的变化进行探讨。分析表明,喷淋进入储罐的LNG液滴并不能完全覆盖整个储罐,液滴进入储罐后,速度迅速衰减并转成垂直下落,同时液滴不断吸热汽化。预冷过程中,LNG的喷淋速度决定了储罐的冷却速度,温降最快的位置出现在储罐底部的中心区域,侧壁温降速度较慢。由于储罐的底部中心区域出现二次流动,阻碍了储罐底壁与内部低温气体的换热,同时由于混凝土对容器的导热,造成容器底部中心区域的温度不减反增的现象。

关键词: 天然气, 汽化, 数值模拟, 储罐, 预冷, 喷淋