Conceptual design and analysis of a novel process for BOG re-liquefaction combined with absorption refrigeration cycle

Abstract

Little attention has been paid to the boil-off gas (BOG) re-liquefaction using the absorption refrigeration cycle (ARC), so a novel process for BOG re-liquefaction combined with the ARC is designed and compared with the traditional parallel nitrogen expansion process. The working fluid of the ARC is ammonia-water solution, and the heat of the reboiler comes from the hot steam heated by the solar energy. Several performance parameters such as specific energy consumption (SEC), exergy efficiency (EXE), coefficient of performance (COP), cold and hot composite curves of the heat exchangers and exergy losses are compared and analyzed. The optimization results show that the process with the ARC performs better. The SEC of the process with the ARC is 0.7878 kWh/kgLNG, which is 11.0% lower than that of the traditional parallel nitrogen expansion process. Meanwhile, the EXE and COP of the process with the ARC are 0.3657 and 0.2636, which are 12.6% and 11.8% higher than that of the traditional parallel nitrogen expansion process. Therefore, this study demonstrates that the process combined the ARC with the traditional processes can improve the system performance. Finally, the cost analysis is given for the two processes.