Apparatus for concentrating water-soluble organic material

An apparatus for concentrating an aqueous solution of a water-soluble organic material which forms an azeotrope with water comprising:

• (a) a first distillation column for preliminarily concentrating said aqueous solution of a water-soluble organic material;
• (b) a second distillation column fed with the liquid preliminarily concentrated in said first distillation column;
• (c) a separator connected to the top of said second distillation column to receive a vapor from the top of the second distillation column and comprising a separation membrane for separating said vapor into water and said water-soluble organic material;
• (d) a condenser disposed at a downstream side of said separator for receiving the vapor in which a fraction of said water-soluble organic material is larger than that in said vapor from the top of the second distillation column;
• (e) means connected to said condenser for withdrawing part of the condensed liquid from said condenser as a product;
• (f) means for recycling the rest of said condensed liquid to the top of said second distillation column for refluxing;
• and (g) means for utilizing the condensation heat of said vapor discharged from the top of said first distillation column as a heat source for vaporizing liquid in the bottom of said second distillation column, further comprising (h) means for recycling the liquid from the bottom of the second distillation column to the first distillation column, and (i) means for condensing the vapor passing through a zeolite membrane and recycling said condensed vapor to the first distillation column.