Comprehensive thermodynamic and economic analysis of an LNG cold energy recovery system using organic Rankine cycle and freezing-centrifugal desalination for power and water cogeneration

Abstract

In this study, the LNG cold energy recovery combined with a freezing-centrifugal desalination system is proposed. The thermodynamic and economic analysis is also carried out of the proposed system. To verify the results of sea ice centrifugation process, experimental analysis of sea ice centrifugal desalination is presented based on different types of sea ice: slurry and solid, which are prepared by the method of suspension crystallization method and progressive freezing method, respectively. The experimental outcomes demonstrated that higher rotation speeds and longer centrifugal times enhanced the desalination rate but resulted in decreased freshwater yield in both slurry and solid ice. For the slurry sea ice, achieving a rotation speed of 5000 rpm and a centrifugal time exceeding 3.0 min resulted in melted water with a salinity level below 0.05%, satisfying the standards of drinking water. Moreover, the unit product cost, payback period, and unit cost of CO2 emission reduction for the proposed system are 0.49 $/t, 3.25 years and 18.92 kg/$, respectively. While the unit product cost, payback period, and unit cost of CO2 emission reduction for the conventional system are about 0.84 $/t, 4.80 years, and 15.66 kg/$, respectively. Hence, the proposed system shows higher economic and environmental performance.