半封闭空间LNG泄漏安全性数值模拟研究

Numerical simulation and study of the safety of a semi-closed space where liquefied natural gas spilling

关键词:  液化天然气  泄漏  爆燃  数值模拟  安全 

Key words:  LNG  spill  deflagration  numerical simulation  safety

摘要:

为了定量评价液化天然气(LNG)加注船上“冷箱”内发生泄漏后的风险,利用计算流体力学软件Fluent对“冷箱”在有、无强制通风条件下发生LNG泄漏后扩散和爆燃的过程进行了模拟研究。结果 表明,在无强制通风时,“冷箱”内发生连续泄漏后,箱内可燃浓度区域随时间先变大后减小,在泄漏后60 s、90 s、120 s、150 s分别点燃时,达到的最大超压依次为29 kPa、89 kPa、76 kPa、70 kPa,会对箱体和人员造成严重伤害;在有强制通风时,泄漏后箱内甲烷浓度场在约100 s后达到稳定,在泄漏后60 s、90 s、120 s、150 s分别点燃时,达到的最大超压依次为1.8 kPa、1.9 kPa、3.0 kPa、3.1 kPa,超压损害很小,但在爆燃后继续燃烧,会对箱体及内部设备造成高温热辐射损害。计算方法和结果可应用于“冷箱”等半封闭空间泄压防爆的安全设计。 

Abstract:

To quantitatively evaluate the risk of the liquefied natural gas (LNG) bunkering vessel with a cold box where LNG spilling, this study simulated the diffusion and deflagrations occurred at different instants after LNG spillage with or without a forced venting by fluid dynamics software Fluent. The simulation results showed that the flammable area increased first and then decreased with time after LNG spilling in the cold box without a forced venting when ignited at 60 s, 90 s, 120 s and 150 s respectively, the maximum overpressures could reach 29 kPa, 89 kPa, 76 kPa and 70 kPa correspondingly, which would cause serious damage to the box and persons. While with a forced venting, the methane concentration field internal cold box became stable soon after spill and the flammable area increased to a constant level. When the gas mixture was ignited at the same time as above, the overpressures were much less than those without a forced venting, as 1.8 kPa, 1.9 kPa, 3.0 kPa, 3.1 kPa respectively. And a fire was predicted resulting from the deflagration, which might cause heat radiation damage to the cold box and carried equipment. The method and results of the calculations could be applied in safety design of the cold boxes or other confined spaces to prevent the explosions and fires.