Techno-economic Analysis of the Potential for Additional Electricity Generation Using Low-Grade Waste Heat Recovery in Gas Turbines

Diego Luis Izidoro¹; Osvaldo José Venturini¹; José Carlos Escobar Palacio¹

¹ Universidade Federal de Itajubá

doi:10.20906/CPS/COB-2015-1174

Resumo

The search for more efficient processes has become a global necessity, due to the growing energy demand and the scarcity of nonrenewable energy sources. Combined cycle power plants are examples of how it is possible to increase the thermal efficiency of an electricity generation process. Despite this, there are heat dissipation points in these plants causing a decrease in efficiency, especially in gas turbines. As examples, one can mention the heat exchangers used for cooling the air extracted from the compressor for further cooling of the turbine vanes. In this way, this paper presents a technical economic evaluation of the potential for additional electricity generating through the utilization of an Organic Rankine Cycle (ORC) powered by these low-grade heat dissipation streams of a gas turbine system. First, Siemens SGT6-5000F gas turbine was modeled using GateCycle software. Then, the spots having the potential for waste heat recovery were identified and analyzed. After that, it was incorporated an ORC in the system. Finally, an economic evaluation was carried out. The results show that it is possible to recover the low-grade heat and generate more electricity while maintaining the same fuel consumption, thus increasing the efficiency and contributing to mitigate the environmental impacts of these systems. The costs associated to changes needed to modify the system are relative small in comparison with the advantages obtained with the additional power generated.

Palavras-chave: Low-grade energy recovery; efficiency; Organic Rankine Cycle; gas turbine; waste heat recovery