Anhydrous ethanol recovery from fermentation liq. - by distn. in series of columns at different pressures

摘要

Prodn. of anhydrous ethanol from fermented must of sugar-contg. material comprises supplying the preheated must in parallel to a series of distn. columns each operating at a different pressure. The first column operates at the lowest pressure, and pressure increases progressively up to the final column which is at elevated pressure. The latent heat of overhead prod. from each column is used to heat the column of lower pressure next to it, and only the highest pressure column is heated externally. Pref. heat in the aq. bottom prods. is used to preheat the feedstream. Aq. ethanol recovered from each column is azeotropically dried in a column, in presence of entraining agent, which is (partly) heated by the latent heat of column overheads. Ethanol (for use as a petrol additive) is now prod. with reduced energy consumption and without use of very high temp. and pressure.