关键词: 液化天然气, 连续泄漏, 垂直喷射源, 重气扩散, 被动扩散

Abstract: Leakage and explosion accidents are often caused by gasket aging,perforated corrosion of pipeline,weld crack,outside force bump,poor management and other reasons in applications of liquefied natural gas(LNG).Research on LNG leak diffusion process will greatly reduce personal and economic loss.A study on LNG diffusion process is conducted for continuous leakage.The diffusion process is divided into two stages,heavy gas diffusion in initial stage and passive diffusion in the following stage.The first stage is described by SLAB steady plume dispersion model and the second stage uses Gaussian plume model.The transformation of heavy gas diffusion and passive diffusion is indicated by a stage transformation criterion.For vertical jet source,the releasing gas rises because of its initial momentum before gravitational diffusion.The rising height of plume is calculated.The mathematical model of LNG diffusion process is set up and used to simulate the diffusion of vertical leakage LNG under two environmental conditions.The concentration profile,temperature profile and other characteristic parameters of mixing clouds after leaking are calculated.The heat and mass transfer between LNG and the environment is analyzed.The influence of heavy air on the diffusion process is explained.These results are helpful in determination of damage range of accident,evacuation of people and guidance of rescue work.

Key words: LNG, continuous leakage, vertical jet release, heavy gas diffusion, passive diffusion