Thermodynamic analysis of natural gas liquefaction process with propane pre-cooled mixed refrigerant process (C3MR)

Abstract

Liquefaction processes plays an important role for transmission of natural gas in long distances. Production of liquefied natural gas (LNG) is classified as an energy consuming process. LNG is a complicated thermodynamics process and the thermodynamics analysis for the key points of the system seems necessary. The goal of this study is to enhance the overall performance and heat recovery from outlet streams of LNG process by changing the process thermodynamics variables. Simulation and sensitivity analysis for two objective functions; specific energy and compressor power consumption were done by Aspen HYSYS process simulator. The investigated variables in this study are four pressure levels, inner and outlet pressures of main compressor and the flow rate of propane in precooling cycle. By considering the process limitations, the possible range for each variable was obtained and then sensitivity analysis was done for each parameter. The obtained results show more improvement on objective functions compared to the other investigations; specific energy for this process was obtained 845 kJ/kg, which shows 30% improvement compared to initial model and the total energy consumption reached to 62.7 MW while it was 71 MW for initial model.