Experimental and Theoretical Study on the Bund Overtopping Process after a Catastrophic Failure of LNG Storage Tanks

LNG is usually stored in large tanks, and the tank volume is up to 230,000 cubic meters. Regulations mandate the Liquefied Natural Gas (LNG) storage tanks to be equipped a bund to control the spilled liquid after a tank failure. The capacity of the bund is usually designed to be 110% of the tank volume, but the 110% rule has been proven to be ineffective to contain all the spilled liquid in the case of a catastrophic tank failure. Therefore, the spilled LNG will overtop the bund, resulting in severe consequences. Previous work mainly used water to study the effect of radius and height of circular bunds on overtopping fraction, other key design parameters of the bund system were barely studied, such as other bund shapes rather than circle, inclination angle of bund walls, and break water. The numerical studies developed Computational Fluid Dynamics (CFD) models of bund overtopping, but the boiling phenomena of LNG was ignored. In this work, the overtopping study was further enhanced by investigating the shape, the inclination angle, and the breakwater of the bund using an in-house apparatus. The numerical study integrated a boiling model into the validated CFD model, which can simulate the LNG boiling phenomena during the bund overtopping process. The findings of this work will help to prevent the bund overtopping of a catastrophic tank failure accident, and provide scientific recommendations on the bund design of the LNG storage tanks.

*Corresponding author: Bin Zhang, bzhang@njtech.edu.cn