Modelling methanol recovery in wine distillation stills with packing columns

Abstract

Methanol is a well known toxic congener that contaminates many spirits. Chilean legislation indicates that methanol content in wine distillates should not exceed 1.5 g/L absolute alcohol (a. a.). To achieve this stringent limit, distillers need new tools to improve their operational policies since trial and error experiments are too slow. In this paper, a fast pseudo-stationary simulator for batch distillations in packed bed columns was developed. Packed bed columns are preferable for batch productions of fruit wine distillations since they have a wider range of stable hydraulic operations. The model was solved using orthogonal collocations and considers a liquid vapour equilibrium model of the ternary water-ethanol-methanol mixture, which accounts for most of the volatiles in wine. Simulations compared favourably with our own laboratory batch distillations of water-ethanol-methanol mixtures. In addition, our model simulations were able to qualitatively reproduce the results reported in the literature for methanol recovery in experimental batch distillations. Ethanol recovery errors were within measurement errors, while methanol simulations showed a 3% bias by the end of the distillation. Hence, the developed model is accurate and could be used to explore optimal operational policies in order to minimize methanol content in the heart cut used in the final product.