As BOG(boil-off gas) production and LNG downstream load fluctuate frequently and sharply at LNG receiving terminal

BOG recondensation process operates with high energy consumption and instability.Through thermodynamics-based analysis of BOG processing system

a BOG multi-stage compression and recondensation process model was established

aiming at lowing energy-consumption as well as improving flexibility and operability of the BOG recondensation process.The model parameters of number of stages and single stage compression ratio were optimized by minimizing the objective function of total energy.The result showed that for a specific BOG and LNG load

the more the stages of the multi-stage compression and recondensation process system

the less the energy consumed(correspondingly

a smaller total compression ratio and a larger processing capacity of BOG); however

the energy-saving effect became more and more insignificant as the system number of system stages increased.Compared with the current one-stage system

operating flexibility of the two-stage system was improved by 12%

and compression energy was saved by more than 33% when the mass ratio of LNG and BOG was less than 10.Two-stage system was recommended for processing BOG at LNG receiving terminal.