Numerical investigation of stratification and rollover characteristics for LNG tanks

Abstract

In the full-volume LNG tank, the leakage of the external heat will increase the internal LNG temperature and aggravate the evaporation of the low-temperature liquid, which may cause delamination and rollover of the LNG in the storage tank, resulting in significant safety hazards. Therefore, this paper analyzes the mechanism of LNG stratification and rollover in storage tanks, establishes the mathematical model of LNG storage tanks, and uses CFD technology, adding the phase change model of LEE by multi-phase flow VOF model. The 2-dimensional transient simulation calculation was carried out in the evolution process of stratification and rollover in LNG storage tanks. The calculation results show that the time of rollover in the LNG storage tank under different working conditions (density difference and heat leakage) is different. Increasing the heat leakage strength of the tank will cause the rollover phenomenon to occur in advance; under the same leakage heat intensity, the LNG of different initial density differences in the tank, the higher the density difference, the easier it is to roll, and the less time is required. Natural convection due to heat leakage is the direct driving force of the rollover phenomenon.