Optimization Analysis of Peakshaving Cycle to Liquefy the Natural Gas

Publisher Summary This chapter analyzes the optimization of three kinds of Peakshaving LNG cycles —namely, nitrogen–methane expansion liquefaction cycle, propane pre-cooled mixed refrigerant liquefaction cycle, and two stages mixed refrigerant liquefaction cycle. The specific power consumption of unit LNG production is used as the objective function. The results of optimization analysis indicate the power consumption of C 3 H 8 pre-cooling mixed refrigerant liquefaction cycle is the least and power consumption of N 2 -CH 4 expander liquefaction cycle is the largest. N 2 -CH 4 expansion liquefaction cycle is compact, flexible and with good applicability but its power consumption is large, so it's suitable for small and medium-sized LNG system, which is used to recycle natural gas resources of marginal gas field. C 3 H 8 pre-cooling mixed refrigerant liquefaction cycle has complicated equipments, its power consumption is low, so it is suitable for large-sized base load LNG system. The three kind cycles are optimized with specific power consumption of unit LNG product as objective function. The optimum results are the optimum value of the objective function and the corresponding process parameters.