Multiphase Simulation of LNG Vapour Dispersion with Effect of Fog Formation

Abstract LNG vapour dispersion known as dense gas dispersion is one of the main hazards from accidental LNG spill and is of critical importance in risk assessment. Most of the previous studies on this topic were conducted in the single-phase framework which is incapable of considering the effect of fog formation. LNG importing and exporting terminals are typically located at coastal areas where there is a high chance of fog formation. In this study, a multiphase CFD model has been developed to investigate the dynamic mixing of cryogenic LNG vapour cloud and ambient air. The effect of fog formation on LNG vapour dispersion was studied. The model was validated by historical experiments conducted by LLNL, upon which good agreements were achieved. Case studies of different relative humidity were performed in order to investigate the LNG vapour dispersion behaviour affected by different fog concentrations. It was found that the affected area of the vapour dispersion is enlarged if the air relative humidity is increased. The findings in this study could improve the understanding of the mechanism of LNG vapour dispersion in humid environments, and help to provide more reliable risk assessments for LNG plants.