(OTC 24127) A Simple Model for Estimating Leak Rates from Flashing Liquid Inventories, in Safety Studies of LNG FLNG Facilities

摘要

A key part of any hazard consequence assessment study is the estimation of the leak rate following failure of part of the process plant. This is the source term that drives the dispersion of the process material, and possibly the subsequent fire and/or explosion if the material is flammable. This estimation is made more complex for LNG facilities, since it is usual for parts of the plant to contain large inventories of pressurized liquefied gas that will flash strongly when the pressure is relieved. Unlike sub-cooled liquid or pressurized vapor, the behavior of a flashing inventory is complex, and requires careful treatment in order that an accurate estimation is made for the inventory release rate. There are a range of modeling approaches that exist in the literature, but these are generally too complex to use in a typical risk assessment study, and so a typical approach taken by the industry to date seems to be to treat the release as a sub-cooled liquid outflow. This paper shows that this is unduly conservative, and presents instead an alternate simple approach that allows a much better assessment of the consequences from these types of process leaks.