Thermodynamic Analysis-Based Improvement for the Boil-off Gas Reliquefaction Process of Liquefied Ethylene Vessels.

A new optimization design of the boil-off gas (BOG) reliquefaction process for liquefied ethylene (LEG) vessels is proposed in order to reduce the reliquefaction process energy cost and improve its cold exergy efficiency. The exergy loss of each component is calculated and the efficiency of the available energy utilization is evaluated on the basis of a detailed thermodynamic analysis. The exergy analysis results indicate that the exergy efficiency of the improved BOG reliquefaction process is about 19.0 % higher than that of the existing process, and the amount of refrigerant used in the improved process is reduced by about 44.9 % per hour. The power consumption could be decreased by 16 %. The circulation volumes of the refrigerant and BOG are both significantly reduced, thus lowering the equipment and operation costs of the BOG reliquefaction process. [ABSTRACT FROM AUTHOR]