Structural, operational and economic optimization of cryogenic natural gas plant using NSGAII two-objective genetic algorithm

Combined pinch and exergy analysis is herein employed to design and optimize a complex integrated structure of cryogenic natural gas plant based on the dual mixed refrigerant refrigeration cycle. Exergy composite curves are applied to reveal possible process improvement. Process intensification can reduce the number of required equipment as well as energy consumption. This integrated structure has specific power of 0.339 (kWh/kg LNG) and exergy efficiency of 66.14%. Sensitivity analysis is used to identify the important parameters affecting on the integrated processes and study behavior of the integrated structure against plant disturbances as well. After identifying important parameters, two single-objective and a NSGAII two-objective genetic algorithms are used to minimize thermodynamic properties and economic values of the integrated structure, simultaneously. Optimization procedure is conducted by structural and operational methods. The amounts of specific power and period of return are decreased by 6.68% and 5.65% by implementing the NSGAII two-objective genetic algorithm.