A New Re-Liquefaction System for Dynamic Boil-Off Recovery Based on Single Mixed Refrigerant

The single cycle mixed-fluid LNG (PRICO) process is the most widely used for natural gas liquefaction. But the optimized energy consumption of single mixed refrigerant (SMR) liquefaction process was still high using the existing energy saving optimization method. The main purpose of this study was to propose an optimization method to combine with the combination optimization of important parameters to improve the system energy efficiency for the SMR structure. The liquefaction process with an initial investment increase of only 6% was designed, by adding initial investment including separator, valve, mixer, etc. The genetic algorithm and liquefaction simulation were used to analyxze the combination optimization of multiple parameters, such as the component ratio of the mixed refrigerant and the pressure of the liquefaction circulation node. Finally, by comparing the similar liquefaction process, it can be found that the optimized heat exchanger internal hot and cold complex curve was better matched, thus reducing the energy Irreversible loss. It indicated that operation energy consumption of the improved SMR process, of which the specific energy consumption could reach 0.247kW·h/kg, was 10.24% lower than PRICO, and the total energy consumption was decreased by 2%. It is thus clear that the optimization method of liquefaction process design and parameter combination has great energy saving efficiency.