Optimization and analysis of natural gas liquefaction process in mixed fluid cascade
The mixed fluid cascade(MFC)process is one of the most competitive processes for large-scale base-loaded natural gas liquefaction process,which consists of three mixed refrigeration cycles of natural gas pre-cooling,liquefaction,and subcooling,which involves key parameters such as refrigerant ratios,refrigeration temperatures,and pressures,which makes the process complex and sensitive.For the MFC liquefaction process,an optimization function with specific power consumption as the objective is established,and with the help of Aspen HYSYS process simulation and physical property calculation,the sequential quadratic programming(SQP)optimization algorithm is used to globally optimize the MFC process and conduct energy efficient analysis of the process.The optimization results show that after the global optimization,the specific power consumption of the MFC liquefaction process is 899.36 kJ/kg,which is 7.38％lower.The cold-heat composite curve of the multi-strand flow heat exchanger is better matched.Through the effective energy analysis,it is found that the effective energy loss of the refrigeration compressor unit accounts for the largest proportion,and the effective energy loss of the multi-strand flow heat exchanger is significantly reduced after the optimization,and the effective energy efficiency of the liquefaction process is increased from 38.17％to 41.21％,and the energy utilization efficiency is improved obviously.
natural gas liquefactionunit power consumptionoptimizationeffective energy analysis
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