Design, optimization and exergy analysis of new generation waste heat recovery and power systems to increase the overall efficiency of the system using exhaust gas heat of a gas turbine

In this study, firstly, the real system parameters (temperature, pressure, power generation and fuel consumption etc.) of the natural gas based gas turbine-based trigeneration system with waste heat of 500 ºC were recorded monthly for a year and the experimental data and theoretical calculations were compared with each other on a monthly basis. Then, three different combined cycle scenarios were designed, including Kalina and organic Rankine cycles, which are novel generation waste heat recovery systems, in which gas turbines are used as the main carrier. In the first scenario, the combined power cycle consisting of the gas turbine (GT), steam Rankine cycle (RC) and organic Rankine cycle (ORC) is analyzed. In the second scenario, the Kalina cycle (KC) system working with an ammonia-water mixture was integrated instead of the ORC system in the first scenario. In the third scenario, GT is used as main carrier and KC and ORC are used as subsystems, respectively. Finally, exergoeconomic analysis was carried out for three scenarios where the Specific Exergy Cost Method (SPECO) was applied. The economic parameters of each scenario were examined in detail and compared. As a result of the study, it has been revealed that the best combined power system in terms of both energy and exergy analysis and economic findings is GT-KC-ORC in which KC-ORC is integrated. Net power, thermal and exergy efficiencies of the GT-KC-ORC combined system were calculated as 2983.57 kW, 48.32% and 47.39%, respectively, while the payback period of the KC-ORC integrated into the system was found to be 1.99 years.