The small-scale skid-mounted natural gas liquefaction plant can recover natural gas economically and conveniently without pipeline transportation. The mixed refrigerant liquefaction process is widely used in small plants currently. However, the liquefaction process is very energy–intensive. In this paper, We simulated the propane precooled mixed refrigerant liquefaction process and found that increasing the pressure and lowering the feed gas temperature can reduce the liquefaction energy consumption. Moreover, parameters such as refrigerant composition, flow rate, and heat exchangers outlet temperature are also related to energy consumption. The genetic algorithm (GA) was used to optimize the process, and the minimum specific energy consumption of liquefaction process ?????? was 0.3821kW·h/kg, which was 37.9% lower than the base case. In addition, the results also suggest that when the C4H10 mass fraction exceeds 35%, the compressor inlet has liquid phase component. When the CH4 and N2 components are less than 20%, the cryogenic heat exchanger has insufficient heat exchange capacity.
Keywords small-scale skid-mounted liquefaction plant, propane pre-cooling liquefaction, mixed refrigerant, genetic algorithm, specific energy consumption