Eventos Anais de eventos
COBEM 2017
24th ABCM International Congress of Mechanical Engineering
Exergy analysis of biogas production in ethanol distilleries
Submission Author:
Rafael Nogueira Nakashima , SP
Co-Authors:
Rafael Nogueira Nakashima, Silvio de Oliveira Junior
Presenter: Rafael Nogueira Nakashima
doi://10.26678/ABCM.COBEM2017.COB17-0185
Abstract
Vinasse is the main liquid effluent of ethanol distillation and, when incorrectly disposed, can cause damages in water and soil resources. Since this effluent has a high concentration of organic compounds, anaerobic digestion is a possible solution to reduce vinasse chemical organic demand (COD) while producing biogas, an alternative fuel. However, this technology has some challenges related to biogas economical devaluation and high investments costs, which demands models to analyze this systems performance. Thus, the focus of this study was to develop a biogas production model, combining Matlab® and Aspen Plus®, to evaluate the anaerobic treatment efficiency by using exergy analysis. The results show that a significant quantity of exergy can be partially retrieved (44-52%) from vinasse with biogas production. In general, increases in hydraulic retention times (HRT) and COD concentrations tend to slightly increment anaerobic digestion efficiency, while high sulfates concentrations have the opposite effect. However, the biogas plant exergy efficiency tends to increase at lower HRT due to higher biogas production and lower portion of untreated vinasse. On average, the main sources of irreversibilities are the cooling system (45%) and the anaerobic reactor (48%). Moreover, the biogas plant performance throughout the year is considerably affected by ethanol production seasonality, start-up times and number of reactors.
Keywords
Biogas, Exergy Analysis, Vinasse, Anaerobic digestion, Ethanol distilleries
