This paper deals with optimal operation of a three-product dividing-wall column (DWC). The main idea is to design a control structure, through a systematic procedure for plantwide control, with an objective to achieve desired product purities with the minimum use of energy. Exact local method is used to find the best controlled variables as single measurement or combination of measurements based on the idea of self-optimizing control. It concluded that it is possible to have better self-optimizing properties by controlling linear combinations of measurements than by controlling conventional individual measurements. Dynamic validation showed that the proposed control structure with the aid of low-complexity simple PI controller stabilized the plant, rejected the effect of disturbances and made DWC to produce product with desired specifications.

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