Abstract: The boil-off gas （BOG） of LNG in an unloaded state is calculated. Based on the opening of the BOG gas-phase outlet valve,LNG loading temperature,and component dimensions,the BOG production is compared by using HYSYS software,and the variation rules of cabin pressure and temperature under different boundary conditions are obtained. According to the rules,suggestions for equipment configuration and operation are proposed.

Key words: FSRU, BOG calculation, BOG dynamic simulation, LNG loading