Techno-Economic and Sensitivity Analysis of Natural Gas Liquefaction Using the Propane Pre-Cooled Mixed Refrigerant (C3MR) Cycle

Liquefied natural gas (LNG) is essential in the global energy transition because it allows for long-distance transportation of natural gas with reduced emissions. Improving the energy efficiency and economic feasibility of LNG liquefaction processes is therefore important. This study offers a comprehensive techno-economic analysis and sensitivity evaluation of natural gas liquefaction using the Propane Pre-Cooled Mixed Refrigerant (C3MR) cycle. A steady-state simulation was developed in Aspen HYSYS V12, utilizing the Peng–Robinson equation of state to accurately model the cryogenic behavior of multicomponent streams. The process was segmented into two integrated subsystems: propane precooling and mixed refrigerant subcooling, with performance measured through key indicators such as energy use, power requirements, and indirect CO2 emissions.

The results show that although the MR cycle uses slightly more electrical power than the propane precooling stage, it leads to lower overall energy use, less cooling water requirement, and significantly fewer environmental emissions. From an economic standpoint, cost estimates based on updated CEPCI indices indicate that these technical improvements result in strong financial performance, marked by high profitability and a quick payback period under typical LNG market conditions. Sensitivity analysis also indicates that higher natural gas feed rates, moderate refrigerant flow rates, and an inlet pressure near 65 bar best balance energy efficiency with economic return. Overall, the findings confirm that the C3MR cycle is a solid and practical option for large-scale LNG production, effectively connecting better thermodynamic performance with positive economic results.