Economic Optimization of Dual Mixed Refrigerant Liquefied Natural Gas Plant Considering Natural Gas Extraction Rate

This study mainly focuses on the profit optimization of the natural gas liquefaction process considering extraction rate. The target process is the dual mixed refrigerant (DMR) process with 1 million tons per annum (MTPA) capacity. The liquefaction ratio and the amount of boil-off gas (BOG) varies according to the natural gas extraction rate to meet the liquefaction capacity. Therefore, utilizing produced BOG and minimizing wasted BOG is key from an economic point of view. This study performed profit optimization with various extraction rates. Moreover, the energy and cost optimizations are performed to analyze the extraction rate effect. As results for the profit maximization, the total compression energy requirement and the plant cost show optimum values between the energy and cost optimization results. The profit increases by 22.5% with 93.2% liquefaction ratio through the optimization. The result shows that producing BOG as the amount of the fuel requirement for the compression energy supply is the optimal extraction rate. Resultingly, the optimal design of the profit max DMR process is also found through the profit optimization.