Exergetic and sustainability analysis of an intercooled gas turbine cogeneration plant with reverse osmosis desalination system

Abstract

In this study, an advanced cogeneration plant based on a 100-MW aeroderivative intercooled gas turbine (ICGT) engine and large two-pass reverse osmosis (RO) desalination system is analyzed thermodynamically. The proposed model has been developed using specialized software and validated with manufacturers’ published data. Saline water is simulated using the latest physical properties available in the literature and treated as a real mixture. Combined energetic and exergetic performance criteria for the design of a cogeneration plant is presented as being, today, the most efficient method for accurate assessment of performance, which also permits quantification of system deficiencies. The performance of the proposed plant was investigated using different loads, ambient temperatures, pressure ratios, and feed water temperatures. The results show an intercooler system improves cogeneration plant performance despite having a negative impact on the combustion chamber performance because of its reduction of compressed air temperature. The ICGT engine is considered the best available choice to integrate with a RO unit because of its high pressure ratio and low power consumption in the compressors. From an operational perspective, full load and low ambient and high feed-water temperatures are highly recommended. The exergetic efficiency of the ICGT engine, RO system, and cogeneration plant are shown to be 44.3, 32.83, and 47.6%, respectively. From a sustainability perspective, the exergetic-environmental efficiency is slightly affected by ambient temperature, whereas it is highly affected by load variation. Based upon the obtained results, numerous possibilities are presented to improve the performance of cogeneration plants.