Applying consistent technology for fuel ethanol production

Abstract

Anhydrous fuel ethanol starting from molasses can be produced through several combined routes by application of different technologies for fermentation, distillation and dehydration processes. Indeed, they constitute chains of processes that must be driven by a specific objective, such as minimising power consumption, steam consumption, losses, improving product quality or plant robustness, among others. The technology applied, however, has an initial investment, which can result in a less competitive plant, if that chain was not constructed under a strict sense of consistency and focused on real results. The present work shows a cross link among the main technologies pointing out their main features, and consistency in chains of production, in order to reach some specific purpose as described above, involving 1-fermentation: continuous, batch, with or without yeast or vinasse recirculation, using centrifuges or floculant yeast; 2-distillation: vacuum, pressurised, in cascade, with side streams or not; 3-Dehydration: mol sieves, extractive and azeotropic distillation and vapour permeation through membranes, with liquid or vapour phase feed. The study concluded that each technology has its optimum in performance for each application in a different chain of technology for the whole process. For instance, some applications of vacuum distillation, fermentation under high yeast stress or with very special yeasts, dehydration under unsuitable route, etc. may be useless for some purposes and may have higher costs in maintenance, product quality control, high process sensitivity etc., despite their higher initial investments. On the other hand, neglecting these technologies may lead the project to a poor approach and consequently to a plant or process unbalanced and inefficient. It is very important to note that both pictures represent a business of lower competitiveness, especially in the case where the chosen technology chain is not robust enough.