METHOD FOR CONCENTRATING AND PURIFYING ALCOHOL AND APPARATUS THEREFOR

摘要

PURPOSE:To improve alcohol concentration degree and economical efficiency by using propylene solvent in a super- or pseudocritical state and simultaneously effectively utilizing compression heat, etc., of a gas in concentrating and recovering an alcohol from an aqueous solution thereof with the above-mentioned solvent. CONSTITUTION:An aqueous solution of a raw material alcohol is fed from an intermediate raw material feed line 2 of a countercurrent contact apparatus 1 and propylene solvent is fed from a disperser 9 in the bottom thereof. The above-mentioned solvent is kept in a super- or pseudocritical state in an alcohol recovering part 7 below the raw material feed line 2 and in a liquid state in a part 6 above the raw material feed line 2 to take out a propylene solvent phase containing the concentrated alcohol separated from water from a taking out line 5 in the upper part. The taken out phase is then introduced into a pressurizing distillation column 11 to recover propylene liquid containing the alcohol without any water from the column bottom 13 and column top 12 and propylene vapor containing water without any alcohol in the reverse. Furthermore, the latter is pressurized in a booster 14 to utilize compression heat as a heat source 15 for the distillation column 11 and part in a propylene solvent return line 17 is returned to the distillation column 11. The remainder in the propylene solvent feed line 18 is subjected to indirect heat exchange with the upper fluid 6 in the apparatus 1 in a heat exchanger 8 and then recycled to the apparatus 1 to concentrate and purify the alcohol in the aforementioned raw material in high purity with saved energy.