Design and Control of a Separation Process for Bioethanol Purification by Reactive Distillation

Bioethanol is one of the most promising alternatives among sustainable biofuels. Methods such as extractive distillation columns are used for the production of bioethanol, because the binary azeotrope of ethanol-water mixture limits the ethanol purity achievable with conventional separation techniques. Since these methods comprise several disadvantages in terms of solvents usage, capital and energy costs, alternative methods are investigated in the industry. This study focuses on the steady-state design and dynamic controllability of a new configuration including a pre-concentrator column and a reactive distillation column to overcome these problems. Steady-state process is simulated using Aspen Plus and Aspen Dynamics is used for dynamic simulations. This configuration is capable to produce ethylene glycol with 99.4 mole% purity as a second product besides bioethanol with 99.7 mole% purity. Dynamic results show that a stable base-level regulatory control is possible for this configuration. Both product purities are held at their design specification against disturbances such as change in production rate handle and feed composition.