Patent ID: 7264696

Claim:
A process for separating by distillation mixtures of substances, which comprises conducting the separation in a dividing-wall column having a dividing wall which is essentially disposed along the long direction of the column, which divides the column interior into a feed part, a take off part, an upper shared column part and a lower shared column part, with feed in whole or in part in the vaporous state of a mixture to be separated between an upper region of the feed part and a lower region of the feed part and/or side stream take off in whole or in part in the vaporous state between an upper region of the take off part and a lower region of the take off part, in which, when the feed is in whole or in part in the vaporous state the cross-sectional area of the upper region of the feed part is increased by plane-parallel displacement of the dividing wall toward the upper region of the take off part and/or when the side stream take off is in whole or in part in the vaporous state, the cross-sectional area of the lower region of the take off part is increased by displacement of the dividing wall toward the lower region of the feed part, in such a manner that the F factor is substantially the same in all column regions and which comprises, to compensate for interference in the feed rate and/or the feed concentration, controlling a division of liquid at the upper end of the dividing wall and at the side stream take off point or points in such a manner that the flow rates of the liquids at the upper region of the feed part and/or the lower region of the take off part or the lowest region of the take off part do not fall below 30% of their usual value.