화학공학소재연구정보센터
Energy, Vol.137, 83-94, 2017
Superstructure based techno-economic optimization of the organic rankine cycle using LNG cryogenic energy
A process design of the organic Rankine cycle utilizing LNG cryogenic exergy is proposed using superstructure optimization. The superstructure imbeds about 1024 possible process alternatives, and the most profitable process configuration and the operating condition are decided simultaneously using a stochastic optimization solver and Aspen Plus-MATLAB interface. The optimum process configuration includes a multi stream cryogenic heat exchanger, a five-stage turbine with reheaters, three stage vapor re-condensation processes and direct contact heaters. In addition, the exergy transfer from the LNG to the working fluid is maximized by using a multi component mixture as working fluid. The 1st law efficiency of the proposed process reaches about 26.2% with 85 degrees C of waste heat source and it is about 42% higher than that of the conventional ORC. The annual profit of the optimum process is about 39 M$ and it can be interpreted as 24$ of profit per kg LNG evaporation. Sensitivity analysis is also presented to show the reliability of the stochastic solution found in this study. (C) 2017 Elsevier Ltd. All rights reserved.