Análise termodinâmica e econômica de diferentes sistemas de cogeração: um estudo de caso de uma usina sucroenergética do interior paulista

Abstract

This paper aims to assess three different cogeneration systems suggested for applying in a sugarcane mill in São Paulo state in order to expand the power generation at the plant. Thermodynamic and economic analyzes were done . The performance indixes of the current configuration and the proposals, called as case 1, case 2 and case 3 consecutively. The analyzes were based on the first and second law of thermodynamics. The economic viability has considered the variation of the selling price of the generated power, implementation costs of the new systems and fuel charges. The current configuration of the sugarcane plant consists of a 63kgf/cm2 boiler, one of 21kgf/cm2 and a back pressure turbine. The first case consists of two 63 kgf/cm2 boilers and two back pressure turbines. The case 2 is composed of two 63 kgf/cm2 boilers and a 21 kgf/cm2 boiler with a back pressure turbine and a condensing turbine. The case 3 comprises a 63 kgf/cm2 boiler and two 21 kgf/cm2 boilers with a back pressure turbine and a condensing turbine. The analysis have been found that the current configuration have shown the best thermodynamic results, however the case 1 and case 3 show themselves attractive economically for minimum amounts of initial investment and average selling prices of electricity.