Control structure selection for four-product Kaibel column

• The proposed three control structures for the four-product Kaibel column are all able to handle the disturbances.
• The feasibility of the proposed process is tested by rigorous simulation.
• Traditional PID control is able to handle disturbances inserted into dividing wall columns.

Dividing wall column configurations have a large savings potential in terms of capital and energy. This paper uses dynamic simulation to investigate three alternative control structures for one of these configurations, namely the Kaibel column. Four components, here selected as methanol, ethanol, n-propanol and n-butanol, are separated into pure products within a single column shell. Control structure 1 (CS1) uses only temperature controllers and is therefore particularly interesting from an industrial point of view. Since the control objective is to control the four product compositions, the two other control structures use also composition controllers. Surprisingly, for composition control, the simple temperature control scheme (CS1) is almost as good at steady-state and much better from a dynamic point of view than the two other more complex control structures.