EXERGETIC ANALYSIS OF A COMBINED CYCLE OF THERMOELECTRIC PLANT
Magali Petry1; Kelly R. Valadares1; Angela Beatrice Dewes Moura1
1 Universidade Feevale
doi:10.20906/CPS/COB-2015-1522
Resumo
According to the national energy balance report of 2013, approximately 76% of the electricity produced in Brazil comes from hydroelectric plants, but this type of generation is very dependent on rainfall. Faced with this difficulty, the government is investing in the diversification of energy sources in order to avoid the occurrence of a new power rationing as there was in 2001. In this context, one of the alternatives that emerged as the second largest supply in the country is the thermal generation, from natural gas, coal, biomass, oil products and others. Thermal power plants are fairly compact, quick construction, low cost and can be inserted close to large consumer centers. Taking into account the importance of thermal energy in the present scenario, it is essential to obtain this energy as efficiently as possible, because the fuel has high cost. Thus the aim of this paper is to perform an exergy analysis of a thermal power plant in operation in the city of Canoas, State of Rio Grande do Sul. This plant has the peculiarity of been dual fuel, i.e., can operate with natural gas or light diesel oil. This is a combined cycle Brayton-Rankine plant, with a gas turbine, heat recovery steam generator with three pressure levels and a condensing steam turbine with reheating. The performance of each component of the thermal cycle was evaluated in order to get results for major losses in efficiency with each fuel. These results open up opportunities for cycle optimization initiatives, as well as a source of research for similar processes development. The modeling used for the exergy analysis of the individual components is based on the methodology proposed by the author Kotas, TJ, where the necessary considerations are done for each component and set the plots of resources, products and losses to be considered in the exergetic efficiency of each part. Calculations were performed in the EES software (Engineering Equation Solver) due to its resources for libraries of thermodynamic properties. Results obtained indicat
Palavras-chave: exergy ; heat transfer; combined cycle