Risk control of overtopping phenomenon after a catastrophic tank failure through optimized bund design

Abstract

Liquid fuels are stored in the large tanks, e.g., LNG (Liquefied Natural Gas). A catastrophic tank failure can suddenly release a huge volume of flammable materials, and cause severe incidents. The Cleveland Natural Gas Explosion resulted in more than 130 fatalities, which was caused by LNG tank failures. Currently, bunds are required by regulations to control the risk of tank failures, e.g., NFPA 59 A; however, there is no specific guideline to design effective bund systems, and overtopping can still occur to undermine the risk control effectiveness of bund systems. This study aims to optimize the bund design for a better risk control of a catastrophic tank failure incident. An experimental apparatus was constructed to simulate the catastrophic tank failure incident, and key parameters of bund design were investigated for their effect to control the overtopping risk, i.e., bund shape, height/radius, inclination angle of bund wall, and breakwater. The experimental data were analyzed to propose a predictive model of bund overtopping fraction. Also, CFD (Computational Fluid Dynamic) models were developed using RNG k-e and LES (Large Eddy Simulation) methods, which were validated against experimental data. The study reveals key parameters of bund design for the overtopping risk control, and contributes to providing a scientific guideline for optimizing the bund design based on both experimental findings and CFD models.