Integração energética da biorrefinaria de cana-de-açúcar para produção de etanol de primeira e segunda geração e energia elétrica

Abstract

The increase in demand for biofuels has driven the development of new technologies such as ethanol production from sugarcane bagasse hydrolysis. Given the importance of Brazil in the ethanol market, the inclusion of technology of second generation ethanol will intensify its production. Energy integration in a sugarcane biorefinery provides important advantages for industrial processes such as better energy management, environmental benefits and increased ethanol production. The last factor is due to lower steam consumption in plant with energy integration, so, less bagasse is needed for cogeneration and a fraction of the surplus can be made available for production of second generation ethanol. In this context, the present study conducted energy integration of a sugarcane biorefinery in order to reduce the consumption of utilities. The technique used was Pinch analysis, an established methodology in the area of energy integration. The biorefinery used in this work consists of process for first and second generation ethanol and electricity production simulated in EMSO software (Environment for Modeling, Simulation, and Optimization). Six different scenarios of biorefinery were evaluated, which differ by pretreatment for bagasse (hydrothermal, diluted acid and steam explosion) and by inclusion or not of pentoses fermentation step. Processes that consider pentoses fermentation step have higher ethanol production when compared to processes that do not make use of pentoses fraction, but steam consumption increases in the same order of magnitude of ethanol production. For the six scenarios evaluated energy integration demonstrated a reduction in energy consumption over 50% when compared to corresponding processes without energy integration and over 30% when compared to process with project integration, as commonly found in Brazilian plants. Besides the economic advantage due to decreased costs of hot and cold utilities, the energy integration provides better energy management, reduction in emission of gases and liquid effluents and increases the availability of bagasse for production of second generation ethanol and/or electricity.