Performance analysis of a gas turbine unit combined with MED-TVC and RO desalination systems

Abstract

The present work deals with a theoretical study on the performance of a combined power and desalination plant. The power is a simple gas turbine unit (GT) while the desalination is composed of thermal and membrane systems. The thermal desalination consists of a multiple effect distillation (MED) with thermal vapor compression (TVC), and the membrane plant is a reverse osmosis (RO) with an energy recovery device (pressure exchanger system). The modeling is based on appropriate evaluation of the sea water properties including that of flow exergy and the solution of mass, energy, and exergy balances for the main components of the power and desalination plant. The simulations include typical data on actual GT units. The effect of the main controlling parameters of the GT plant mainly the pressure ratio and the turbine inlet temperature on the total production rates of fresh water is presented and discussed. An exergy analysis showing the destruction rates of the overall system as well as its main components is also presented. Besides, equations describing the variations of the power output with the air and the distillate mass flow rates are given.