Part load operation of an integrated solar combined cycle using the brine heater of a MSF desalination unit as a steam condenser

Abstract

Hot-climate countries, like Egypt, have an energy surplus while suffering water scarcity. Energy surplus causes frequent part load operation of Integrated Solar Combined Cycle (ISCC) power plants. The present work proposes a cycle that combines an ISCC with a Multi Stage Flash (MSF) desalination unit. The brine heater of the MSF desalination unit acts as a steam condenser for the ISCC. The condenser pressure/top brine temperature of the MSF desalination unit controls the ISCC part load operation. A simulation model for an actual ISCC in Kuryamat-Egypt was developed and validated. A validated model for the MSF unit was integrated with the developed ISCC model. The proposed cycle (ISCC-MSF) was simulated under different operating and geometric conditions. The simulation results were used to optimize the MSF desalination unit and achieve a performance ratio of 11.65 and a 7.7% reduction in the stage area. Cost analysis was performed for the unit production cost of fresh water (UPCMSF), where a reduction of UPCMSF to 0.77$/m3 was achieved. Further reduction of UPCMSF down to 0.54$/m3 can be attained by reducing the interest rate from 5% to 1%. Detailed part load performance investigation of the proposed cycle is recommended for future work.