Numerical study on spill and dispersion of large LNG tank

Based on Fluent's Eulerian multiphase model, combined with phase equilibrium and Gaussian diffusion principles, this study simulates LNG tank leakage and analyzes the effects of wind speed, spill rate, and surface roughness. Results show that the continuous gas cloud diffusion process comprises three stages: heavy-gas diffusion, passive diffusion, and dilution dissipation. As wind speed increases, the maximum \mathrm{CH_4} concentration (at 0.5% volume fraction) exhibits a decrease-increase-decrease trend; when wind speed exceeds 6 m/s, it promotes gas cloud dissipation. Higher spill rates enlarge the pool diameter, pool length, and downwind distance to 0.5 lower explosion limit, significantly expanding the explosion hazard zone. Greater surface roughness reduces horizontal spread but increases the accumulation height of combustible gas clouds. Wind speed and spill rate primarily affect horizontal diffusion, while roughness mainly influences vertical accumulation. These findings clarify large-tank leakage laws, supporting safety design and emergency management at LNG receiving stations. They help reduce explosion risks and improve accident response efficiency.