Patent ID: 8419903

Claim:
A method for manually or automatically controlling at least one of composition and quality of one or more products withdrawn from the top, bottom or side offtake of a distillation column with a built-in heat exchanger, wherein when the pressure in the column is changed in the region of product withdrawal, then the new boiling temperature of the product at this pressure is determined from the vapor-pressure curve of the product, and the temperature of the distillate withdrawal is set at this new boiling temperature, comprising: installing the heat exchanger in the distillation column; and setting the temperature of the distillate withdrawal at the new boiling temperature by means of a changed flow of a cooling medium through the heat exchangers, until the temperature in the column in the region of product withdrawal has reached the new setpoint as determined from the vapor-pressure curve, wherein the cooling medium outer is in the bottom of the distillation column, or the cooling medium is conducted through a bottom medium.