Modeling an innovative low-temperature desalination system with integrated cogeneration in a concentrating solar power plant

Abstract

The thermal desalination systems like multi-effect distillation and multi-stage flush have gone through a strong development process to increase energy efficiency and to improve energy recovery. While these improvements have led to lowered energy consumption, different concepts could be necessary to adapt the thermal desalination systems to renewable energy sources. A specially designed low-temperature desalination driven by low-grade waste heat can be used to desalinate seawater and to clean polluted water with a higher conversion ratio than existing systems. The reason for this improvement is a drastically improved heat transfer of this system, using spray systems for evaporation, and condensation. It was tested in a demonstration plant in El Gouna, Egypt, in cogeneration with diesel generators which used 7 MWth to desalinate 500 m³/d. This paper introduces a model of the low-temperature desalination process, which is derived from experimental data and technical specifications. It required the development of energy, mass, and material balances of the media streams with respect to the measured data from the demonstration plant. The model is implemented using the energy process simulation software “Ebsilon Professional” and combined with a 10-MWth concentrating solar power (CSP) plant. The results show the cogeneration of 2.2 MWel power in the CSP plant and 520 m³/d fresh water in the desalination. Furthermore, the output depends on various process parameters like cogeneration fraction, temperature levels, and input salinity, which are analyzed and discussed.