Performance Analysis of Combined Humidified Gas Turbine Power Generation and Multi-Effect Thermal Vapor Compression Desalination Systems

Abstract

Humidified gas turbines (HGT) have been identified as an promising way of producing power and their use in combined power and water desalination systems is analyzed, employing energy and exergy performance criteria. Based on two representative HGT cycles, the steam-injected gas turbine (STIG) cycle and evaporative gas turbine (EvGT) cycle, two combined systems are proposed. After analyzing the characteristic of desalination units, a multi-effect thermal vapor compression (METVC) unit run by the exhaust heat of the power cycle is chosen to produce fresh water from seawater for both general use and the HGT humidification. Some of the main results are: the fuel consumption of water production in a STIG-based combined system is about 45% of a water-only unit, and that in a EvGT-based system it is 31%~54%; compared with the individual power-only and water-only units, the fuel savings of the two combined system are 12%~28% and 10%~21%, respectively; a water production gain of more than 15% can be obtained by using a direct-contact seawater-gas heat exchanger to recover the stack heat; and the two combined systems are more flexible in their power-to-water ratio than currently used dual-purpose systems.