Análise exergética da produção de etanol de primeira geração a partir da cana-de-açúcar

Abstract

In the present work, energy and exergetic analyzes of plant of an autonomous distillery were carried out for the production of first generation ethanol. The standard plant was granted from bibliographical data of scientific works of the area and data collection in two distilleries of the Brazilian northeast. The final configuration considered consists of the following processes: extraction system, broth treatment, concentration by evaporation, alcoholic fermentation and distillation. Through the first and second laws of thermodynamics, it was possible to evaluate the efficiency and the generation of heat and power for each component that comprised the evaluated plants, as well as the global energy utilization of each of them. Through indexes based on the first law of thermodynamics, it was possible to collect the necessary to validate the plant, based on mass and energy balances. In addition, some indicators have also been calculated that are quite common in alcohol distilleries, such as specific steam consumption of steam turbines or specific consumption of process steam. After an exegetical analysis were found irreversibilities of each subsystem, in addition to the exegetical efficiency, such indexes are of crucial importance for the analysis of thermal processes, as was the case of the plant under study. The analyzes showed the great possibility of reduction of losses and possible utilization of unused flows during the system, such as the exhaust of the flash balloon during the broth treatment process, it was possible to identify the main points of irreversibility of the production process , which are mainly located in the stages of fermentation and distillation, the analysis still pointed to the need of the cogeneration system integrated to the system as a way to mainly meet the needs of the extraction process