Abstract:

Liquefied natural gas(LNG)jet release is common in LNG leakage accidents.It is very difficult to judge the leakage diffusion area through the senses for natural gas is colorless and odorless.While jet release can make the water vapor in the surrounding air into a visible cloud of steam due to its low temperature.Through the establishment of LNG jet release computational fluid dynamics(CFD)model,numerical simulations under different environmental conditions and jet velocity have been carried out,and the temperature field and species concentration field at different conditions are obtained.According to the environmental conditions and the temperature field distribution,the visible vapor cloud area can be ranged.The relationship between the distances at the lower flammability limit(LFL)concentration occurs and that corresponding to the visible contour of LNG vapor clouds has been summed up.During an emergency,the work can be a helpful to indicate the danger of cloud ignition and exclusion distances forecast.

Key words: LNG, jet release, visible vapor cloud, diffusion, LFL, CFD, numerical simulation

摘要：

喷射泄漏在LNG泄漏事故中比较常见,由于其蒸汽本身无色无味,难从感观上判断其泄漏扩散范围。但由于其温度低,喷射泄漏会使周边环境空气中水蒸气液化成可见蒸汽云。通过建立LNG喷射泄漏计算流体力学模型,对不同环境条件和喷射速度下的扩散情形进行数值模拟,得到了LNG泄漏扩散区域的温度场和浓度场。根据环境条件和温度场分布,得到了可见蒸汽云区域范围,并总结出可见蒸汽云区域范围与爆炸下限区域范围的关系。喷射泄漏发生时,可以为预测爆炸下限区域范围,划定安全隔离范围和消防救援提供帮助。

关键词: 液化天然气, 喷射泄漏, 可见蒸汽云, 扩散, 爆炸下限, 计算流体力学, 数值模拟