Hazard analysis by leakage and diffusion in Liquefied Natural Gas ships during emergency transfer operations on coastal waters

With global warming and 2050 carbon reduction targets, the demand for Liquefied Natural Gas (LNG) marine transportation continues to increase. LNG carriers that experience emergency unseaworthy accidents at sea have the need for emergency transfer rescue, which brings many safety management issues for ships and coastal waters due to high risk of LNG leakage. This paper investigates the impacts on the ship and marine safety caused by the LNG leakage and diffusion from ship-to-ship (STS) emergency transfer operations on coastal waters. Firstly, the computational fluid dynamics (CFD) method is used to establish an LNG STS transfer leakage diffusion model. Then, LNG dispersion characteristics and the range of the vapour cloud in transfer operating waters under accident conditions with different wind speeds and wind angles are calculated and simulated. The results show that the diffusion of LNG vapour cloud is significantly influenced by wind speed and hull restrictions, and the flammable volume fraction and 1% volume fraction of the LNG vapour cloud spread to different distances through transport effect, mixing and dilution effect of wind. In addition, an LNG cryogenic hazard zone exists in the vicinity of the leakage point. This study can provide the guidance to authorities to formulate disaster prevention, mitigation regulations, and emergency response measures, which can benefit marine safety management in coastal waters.