COMPARATIVE ANALYSIS OF EXERGETIC BALANCE METHODS IN ALCOHOLIC DISTILLATION COLUMNS

Abstract

The comparison between three methods to calculate the exergy of the currents involved in the exergetic balance of alcoholic distillation columns is presented. Exergy of the currents was considered as: 1) flow exergies, 2) heat exergies and 3) the sum of flow exergy and chemical exergy. The implementation of the exergetic analysis was examined as a key point to improve the efficiency of the process. A case study, where the methods are applied for the evaluation of the exergy is analyzed; differences among the methods were obtained between the 15% and 30 %. The influence of the studied columns in total work capacity loss was determined, concluding that regardless of the method, the distillation column has shown the higher loss. An economic analysis was made applying the first method to the case study, where the percentage of ethanol in wine increases from 5.8 oGL to 9 oGL, which led to a decrease of vapor consumption of 23.66%, an exergetic yield increase of 28.02 % and a combustion gas flow reduction of 24 627 034.4 m 3 /year.