Objective In the major systems of liquefied natural gas (LNG) receiving stations, the safe operation and energy saving of boil-off gas (BOG) treatment process systems are analyzed and studied.

Method The existing recondensation process and the second-order compression recondensation process of the receiving station were compared and analyzed. Based on the second-order compression recondensation process, the secondary precooling optimization was proposed. With the actual operation data of a domestic receiving station and the use of ASPEN-HYSYS software for model establishment and simulation analysis, different simulation models were established for different working conditions.

Result The improved second-order compression secondary precooling recondensation process could be effectively optimized for different working conditions. The research results were combined with the data of an actual receiving station for simulation verification. The data results showed that the total energy consumption of the optimized process was reduced by 606.2 kW compared with the original process, and the energy saving rate was 14.14%.

Conclusion The BOG temperature and the outlet pressure of the BOG compressor have the greatest influence on the recondensation process, and then the optimization method is obtained, that is, the specific enthalpy of the compressor outlet is decreased by reducing the outlet pressure of the compressor, and the pre-cooling process is used to offset the effect of the material ratio increase caused by reducing the outlet pressure of the compressor. Finally, the purpose of reducing the total energy consumption is achieved.