Simulação do processo de destilação com recompressão mecânica do vapor para a produção de etanol.

Abstract

The distillation consumes great percentagem of energy used in the industry and consequently, an improvement of the energy efficiency is the way to decrease the final cost of the product. The separation of system ethanol-water is the main problem in the production of the alcohol for fermentation; because the feeding is diluted, needing great amount of energy for its recovery, until close of its azeotrope composition, for conventional distillation. The object of the present work to decrease the energy consumption in the phase of concentration of the ethanol. This study was divided in two parts: conventional distillation and vapor recompression distillation. The first one, simulates the conventional unit, seeking to establish great conditions of operation with the objective of reducing the amount of necessary energy to the reboiler. After that, the flexibility of the system is evaluated, in terms of variation of the feeding temperature, compositions of the feeding and of the distilled. The second part simulates two distillation models with mechanical vapor recompression: RMVL and RMVH; the model RMVL operates with low pressure in to reflux vase, it means that the system works the pressure of the column, while RMVH operates with high pressure in to reflux vase, in means that the pressure of discharge of the compressor. The main objective is to evaluate the efficiency in energy terms of those models and comparing the results with those obtained from the conventional distillation. The results shown that the model RMVL presented better performance than RMVH and also the recompression system shown great economy of energy. As the system ethanol-water presents a behavior of non ideal in the liquid phase, the model UNIFAC was used for the correction of that phase.