PURPOSE: To prepare absolute ethanol from dilute ethanol raw material, economically, by using a pair of concentration columns, heating the azeotropic distillation column and the pot of the solvent recovery column with the vapor from the top of the first concentration column operating under pressure, and heating the pot of the second concentration column with the vapor obtained from the top of the second column after compression.

CONSTITUTION: Absolute ethanol is prepared from dilute, slurry ethanol raw material by using a distillation apparatus composed of concentration columns, an azeotropic distillation column and a solvent recovery column. The concentration columns A and B are connected with each other in series, and the first concentration column A is operated under pressure. The vapor 2 obtained from the top of the first concentration column is used for the heating of the pots E-4 and E-6 of the azeotropic distillation column C and the solvent recovery column D each operated under normal pressure, and then supplied through the line 5 to the middle part of the second concentration column B operated under normal pressure. The vapor 7 obtained from the top of the second column B is compressed by the compressor G, and used for the heating of the pot E-3 of the second column B. A part 8 of the used vapor 7 is recycled to the column C, and the remaining part 8 of the vapor 7 is returned to the top of the column B. The bottom liquid 6 of the column B is recycled to the column A. Absolute ethanol 11 can be obtained directly from the raw material 1 with reduced energy consumption, by this process.