| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for controlling a plate distillation column, wherein, by the method, an effluent from the column bottom having a composition within a specified range can be surely obtained. SOLUTION: This method comprises feeding a raw material liquid to a plate distillation column having a plurality of plates 1 to N and, at the bottom of the column, provided with a reboiler 52, and performing fractionation. The raw material liquid comprises a low boiling component, a high boiling component and an azeotropic agent. The heat quantity for heating the reboiler is set based on the feed of the raw material liquid. The number of plates, on which the liquid is separated to two phases, is decided based on an impure high boiling component in the distillate and an impure low boiling component in the bottom product and, at the top of the column, the total reflux amount of the low boiling component and the azeotropic agent is controlled so as to keep the number of the plates. The ratio of the low boiling component to the azeotropic agent in the overhead reflux liquid is controlled by valves 32 and 42 based on the concentration ratio of the impurity low boiling component to the azeotropic agent in the bottom effluent.
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