大型液化天然气储罐内罐寿命计算分析

大型液化天然气(LNG)全容罐是LNG接收站项目中最重要的设备之一,在LNG低液位与高液位循环操作期间(卸船周期内)、大修时空液阶段、水压试验与试验水排空等循环使用中,受低温收缩、液位变化等影响,内罐壁-底连接大角焊接接头、壁板、锚固带等危险部位会产生材料使用疲劳,若按LNG储罐50a设计寿命考虑,需对内罐易疲劳关键部位进行材料疲劳校核分析。以国内某已建LNG储罐为例,针对储罐在预冷、水压试验、低-高液位循环使用等工况,对内罐底部大角焊接接头、罐壁板、锚固带等部位材料进行了材料疲劳失效风险分析,对内罐50a设计寿命进行了校核分析。

Calculation Analysis on Inner Tank Design Life of Large Liquefied Natural Gas Tank

Large liquefied natural gas （LNG） full containment tank is one of the most important equipments in LNG terminal project. During the inner tank operating from high operating level to low operating level （unloading cycle）, overhaul phase with no liquid, hydrostatic testing and emptying test water recycling operating conditions, as cryogenic shrinkage and liquid level changes, there is a large material fatigue damage in the inner tank shell and floor junction fillet welds, shell, anchor strap etc. If consider in the 50 years design life of LNG tank, it need checking the fatigue failure analysis for the key parts. Using the parameters of one built tank in domestic LNG projects, an analysis was made for the material fatigue of the inner tank shell and floor junction fillet welds, shell, anchor strap in commissioning, hydrostatic testing, low and high level recycling operating conditions. At last, the 50 years design life of LNG inner tank was checked.