Recuperação de energia na destilação do sistema etanol-agua

AUTOR(ES)
DATA DE PUBLICAÇÃO

1983

RESUMO

Energy recovery is now days one the most important tasks that chemical engineeries face, specially when distillation is involved. Between the energy recovery techniques to be applied to distillation columns, vapour recompression has been pointed out as one of the most promissing. The application of this technique has been discussed in the literature and recomended for distillation systems with high latent heat of vaporization and presenting a low temperature profile across the column, although no detailed work has been published related with the operational conditions of distillation columns. Hence, the present work undertaken study the application of the heat-pump principles to the distillation of the ethanol-water system, obtaining the azeotrope under various operational conditions, as this systems thus not fallows the above recomendations. In order to compare energy recovery of distillation columns using the direct vapour recompression conventional distillation columns were simulated, using the Newton-Raphson generalized method together with the block tridiagonalization of Jacobian matrix. Equilibrium data was obtained using the UNIQUAC method, and a constant Murphree efficiency of 70% was assumed for all the distillation trays. The simulation included a minimization procedure technique for the total number of trays required to obtain the azeotrope, for each one of the operational conditions of the column. The results obtained from the conventional column simulation requeriments for the direct recompression technique, using polytropic compressors were the discharge pressure was minimized during the calculations. The effects of column feed temperature and composition, reflux ratio and polytropic efficiency of the compressor upon energy recovery are analysed. The results show that the use of vapour recompression to distillation of ethanol-water appear to be a good alternative to conventional distillation as energy recovery between 70 to 80% is obtained, specially when feed composition and temperature are low. The work WJS extended to the case when an inert gas (N2) is introduced in the recompression circuit. The results show that an increase in compressed, causes a decrease in the compression ratio, although nitrogene should be added only in quantities up to 200%, as higher amounts of nitrogene lead to low energy recovery

ASSUNTO(S)

destilação alcool

ACESSO AO ARTIGO

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