LNG燃料船气罐连接处所内的泄漏试验及数值模拟研究

为明确现有液化天然气(LNG)燃料船气罐连接处所使用过程中需遵循的各项指标,对气罐连接处所内LNG泄漏进行了试验和数值模拟。试验以典型尺度等比不锈钢方盒为箱体,附带一个每小时换气30次的通风系统来模拟实际模型,LN2作为媒介,对气罐连接处所的安全性进行了测试,并基于挪威三维计算流体力学(CFD)软件FLACS对相关场景进行了仿真计算。试验发现在一般条件和恶劣条件泄漏时,现有的船用气罐连接处所内没有形成累积压力；当处所内低温液体液位达到0.3m时将气罐连接处所完全封闭,2分钟后处所内累积最大压力仅为0.0012MPa,不会对处所强度构成威胁,FLACS计算结果与试验结果完全吻合。采用FLACS软件对2分钟以后的场景进行了模拟分析,计算结果显示气罐连接处所在完全封堵下发生LNG泄漏的极限承载时间大约为4分钟。研究结果表明,现有的船用气罐连接处所设计时可忽略累积压力的影响,但考虑到极限条件存在,需对该处所进行评估,制定极限条件下的应急预案。

Experimental and Numerical Study of LNG Leakage in the Tank Connection Space Onboard

To find out the accumulated pressure in the tank connection space on liquefied natural gas fueled ship after a large amount of LNG spill, a set of experiments and numerical study was conducted. The tank connection space model is made of 304L stainless steel and with a dimension of 2m×2m×2m. Liquid nitrogen (LN2) was used as a safer analogue of LNG. Two pressure gauges were equipped on the top, a ventilation fan with a capacity of air change 30 times per hour was equipped to simulate the real ventilation situation, and numerical simulation for the related leakage scenario had been implemented. Experiments results showed that whether the ventilation fan works or not, there is no accumulated pressure in the tank connection space during the whole test. The results of the numerical simulation demonstrate that FLACS can be considered to accurately simulate the leakage of LNG in the tank connection space.