Avaliação da viabilidade energética e exergética de um sistema de cogeração em uma usina sucroalcooeira no estado de Pernambuco

Abstract

The demand on the consumption of electricity in various sectors and the concerns about the environmental impacts of exploration and use of fossil fuel, has encouraged the study of various alternative energy sources, including wind, photovoltaic, biomass and hydropower. The use of biomass such as sugarcane bagasse in Brazil is a technically viable option that can reduce the emission of greenhouse gases. Thus, the study consists of an energy and exergetic analysis for a simplified configuration of a sugarcane plant, located in the state of Pernambuco, with an electric power generation capacity of 11.8 MWh by burning sugarcane bagasse with 50% of moisture. Thus, for the analysis, equipment data, plant parameters and references found in the literature for similar cases were considered. The analysis of the combustion process in the set of boilers determined the high heat value of 10,299 MJ/kg for a molar mass of 14.26 kg/kmol of bagasse, with the thermal efficiency of the set of boilers being 61.5%. The energy analysis of the generating turbine set and the drive turbine set resulted in 8974 kW and 1980 kW, respectively, for the shaft powers. Through the exergetic analysis it was found that the largest portion of exergy destroyed is in the set of boilers (85.34%), in the condenser (8.59%) and in the set of generation turbines (4.66%). The plant's exergetic efficiency (5%) demonstrates the need for performance improvement projects.