根据LNG卸料臂管道中气液两相流以及多次实际接卸过程中的预冷参数分析可知,LNG卸料臂在卸货初期出现剧烈振动的主要原因是卸料臂管道中气液处于混合状态,卸货后出现气阻现象,由于前后压力不平衡,导致卸料臂振动.针对以上问题提出相应措施:在预冷结束与启动货泵期间,通过泄放阀继续对卸料管线泄放,将产生的BOG排放至BOG总管;船上卸货泵启动后,根据LNG流量对泄放阀进行多次开关,直至泄放阀过流为液体时结束泄放;开始卸货后,船方逐个启动货泵,保证流量稳定,同时及时与陆上操作人员沟通,做出相应操作.经实践,上述措施可有效预防卸料臂在卸货初期的振动,为顺利接卸LNG船提供了有力保障.%According to analysis of gas-liquid two-phase flow in pipelines of LNG unloading arms and pre-cooling parameters of several actual unloading processes, the main reason of the vibration of unloading arms at the beginning of unloading is got. Gas and liquid in unloading arms are in mixed state,so the air resistance phenomenon appears after unloading,which makes unbalance between pres-sures before and after and then leads to the vibration. Aiming at above problems, countermeasures are proposed: BOG is discharged into BOG manifold by continuing bleeding through the bleed valve from the end of the pre-cooling to the starting of cargo pump; after the ship unloading pump starts, the bleed valve should be switched for many times according to LNG flow until the overcurrent of the valve is liquid; cargo pumps should be started one by one by the ship to ensure flow stability,and at the same time to communicate with onshore operators in time and then make appropriate actions. Through the practice,the measures can successfully prevent the vibration of LNG unloading arms at the beginning of unloading,which provides strong guarantee for smoothly unloading LNG ship.
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