Boil-Off Gas Two-Stage Compression and Recondensation Process at a Liquefied Natural Gas Receiving Terminal

Due to ship unloading and the change of downstream gas consumption, the boil-off gas (BOG) and liquefied natural gas outputs fluctuate constantly, causing difficulties in both the design and operation of the BOG handling process. The high energy consumption, instability, and inflexibility of the original process affect the operation cost and running safety of the terminal to a large extent. To address these problems, a two-stage compression and recondensation process is designed and optimized, based on the original one. Compared with the original process through dynamic simulation, the design process has better stability, benefiting from lower operating pressure and smaller fluctuations of both the pressure and the liquid level in the recondenser. In addition, the power and BOG emission are remarkably reduced, which will soon bring great benefit and recovery of investment cost.