关键词: LNG冷能, 朗肯循环, 目标函数, 最小温差, 优化

Abstract: The simulation model of LNG cold energy Rankine cycle power generation system is introduced, and its economy is analyzed. Using the ratio of system heat exchange area to net electric generation as the objective function to evaluate the investment efficiency, the cycle characteristics and process parameters of propane, propylene, ethane and trifluoromethane under different operating conditions are studied. The results show that the exergy efficiency of propylene system is higher than that of the other three, and the exergy efficiency of propane, ethane and trifluoromethane decreases in turn; the choice of medium has obvious influence on the value of objective function, and even in some cases, the difference of objective function caused by different circulating working medium can reach 1.3 times; taking the minimum objective function as the objective, the minimum temperature difference of condenser is 5 ℃, while the minimum temperature difference of superheater should be greater than 6 ℃; taking the objective function as the main evaluation index, ethane and trifluoromethane are more suitable as working medium of LNG cold energy Rankine cycle power generation system.    

Key words: LNG cold energy, Rankine cycle, objective function, the minimum temperature difference, optimization