Optimization and analysis of mixed refrigerant composition for the PRICO natural gas liquefaction process

•The optimal energy solution of the PRICO process was searched by Genetic algorithm.•The heat transfer process in the cold box was divided into 3 regions.•The effect of the MR composition on the shaft work requirement was analyzed.•Principles were proposed to judge the fitness of the MR composition of PRICO.

In this paper, the energy optimization of the PRICO natural gas liquefaction (LNG) process was performed with the genetic algorithm (GA) and the process simulation software Aspen Plus. Then the characteristics of the heat transfer composite curves of the cold box were obtained and analyzed. Based on it, the heat exchange process in the cold box was divided into three regions. At last, in order to find the relationship between the energy consumption and the composition of the mixed refrigerant, the effects of the refrigerant flow composition on the temperature difference and the pinch point location were deeply investigated, which would be useful to guide the refrigerant charging.