Desenvolvimento e avaliação de partida de um sistema de colunas de destilação termicamente acopladas para a obtenção do etanol anidro.

Abstract

Preventive and/or corrective maintenance procedures in equipment’s process operations provoke periodically shut down in the plants. After the maintenance and commissioning step conclusions, initiate the equipment’s startup operation. The start-up operation of chemical processes, in particular distillation columns, is one of the most complex operations in industrial practice. The start-up procedure of a distillation column occurs in few hours or can to wait days to reach steady state. The longer the time required for the operation of the column reaches the steady state, the greater the amount of off-spec product and greater energy consumption. Therefore, the starting operation has a significant impact on operating costs. Although the startup operation is a step of great importance in chemical plants, still is little the number of researches performed with respect to this subject. Moreover, the literature focuses on startup conventional distillation columns. To fill this gap, this work focused startup distillation column thermally coupled. The system studied consists of two distillation columns. One of the columns is extractive distillation type used for separating the azeotropic mixture ethanol-water. The other is a solvent recovery column. The two column is interconnected by two streams. A stream is in vapor phase, and the another stream is in liquid phase. The dynamic behavior of the system was evaluated during the startup operation in a reference configuration. Then was studied the effect of varying the heating steam flow profile in the reboiler, the effect of the feed stream composition of the recovery column and the effect of the start solvent feed extraction column in the total startup time. From the results obtained, it was observed that the recovery column is responsible for most of the time required for completion of the starting. The smaller the amount of ethanol fed to the recovery column, the lower the total time of system startup. It was also observed that the solvent should be fed since the beginning of the start-up operation, because the later the feed of the solvent in the extractive column, the greater the total start-up time.