Method and apparatus for dehydrating mixtures of organic liquids and water

In a method of dehydrating a mixture of an organic liquid and water, which comprises subjecting the mixture to initial distillation to remove an initial quantity of water followed by membrane permeation to remove substantially the remaining water, the improvement which comprises withdrawing at least a portion of the material retained by the membrane separator, passing that material into indirect heat exchange relationship within the distillation column and recycling at least a portion of that withdrawn material back to the separator, the quantity of such recycle stream being such that substantially the whole of the heat required for the membrane permeation is transmitted to the recycle stream during said heat exchange within the distillation column.