Comparative evaluation of processes for obtaining hydrated anhydrous bioethanol of the 1st and 2nd generations using the rate-based model

Author(s)

Michelli Fontana

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia Química
• Defense date: 2021-07-06

Examining board members

Maria Regina Wolf Maciel; Patrícia Fazzio Martins Martinez; Tassia Lopes Junqueira

• Advisor: Rubens Maciel Filho; Maria Regina Wolf Maciel

Abstract

Bioethanol is one of the most used renewable automotive biofuels from renewable source, with great potential for replacing fossil fuels such as gasoline or also to be used as its additive. To obtain anhydrous bioethanol in purity according to the legal parameters of application as a gasoline additive, it is necessary to apply more complex separation processes. This is necessary, as the mixture of bioethanol and water forms an azeotrope, which implies the difficulty of separating them through conventional distillation. In addition, conventional processes for separating hydrated bioethanol must also be improved to operate with high performance. Thus, the aim of this study was to evaluate the conventional and double effect distillation processes to produce hydrated bioethanol of the first and second generations and the extractive distillation and adsorption processes by molecular sieve to produce anhydrous bioethanol. The processes were evaluated through simulations using the equilibrium and rate-based models in the Aspen Plus® simulator. The analyzes focused on the energy demand of the processes, equipment sizing and, in the case of hydrated bioethanol, the production of the vinasse by-product was also evaluated. It was observed that the double effect distillation process provides energy savings compared to conventional distillation to produce hydrated bioethanol. In contrast, double effect distillation required columns with a larger diameter, which may result in a higher capital cost. In the case of anhydrous bioethanol production, the use of the deep eutectic solvent ChCl:Urea (1:2) in extractive distillation showed energy savings compared to the conventional ethylene glycol solvent. In addition, the operation with ChCl:Urea (1:2) required lower solvent content in the process than the operation with ethylene glycol. Comparing the extractive distillation with the molecular sieve adsorption, it was noticed that the molecular sieve adsorption provides low recovery of ethanol, however this process has the advantage of not requiring the addition of a solvent, which can be a positive factor for production of ethanol in applications that require high purity content. Regarding the models used in the simulations, it was observed that the analyzes conducted by the rate-based model required columns with more distillation stages than the columns evaluated by the equilibrium stage model and presented higher energy demand, which was already expected, since the rate-based model is able to provide a more realistic prediction of the process conditions (AU)

• FAPESP's process: 19/24071-0 - Comparative evaluation of processes for obtaining 1st and 2nd generation hydrated and anhydro bioethanol using models of non-equilibrium stages
• Grantee: Michelli Fontana
• Support Opportunities: Scholarships in Brazil - Master