Vapor recompression-assisted
dividing wall columns (VRC-DWCs) with a middle partition have been
shown to have a higher energy efficiency compared to conventional
DWCs. However, the controllability of this highly integrated process
remains as a challenging issue since all of the benefits of a VRC-DWC
are reasonable only under good dynamic controllability. Compared to
the control of the vapor recompression-assisted dividing wall column
with an upper or a lower partition, the control for this kind of process
is more difficult since it has less degree of freedom. Hence, this
paper develops three novel and effective control structures for VRC-DWCs
with upper middle, lower middle, and center middle partitions, respectively.
In the proposed control structures, the compressor work is selected
to control the main column’s bottom purity and the flowrate
of vaporized bottom liquid is selected to control the temperature
of the outlet compressed vapor. The dynamic simulation results for
three separation cases reveal that the proposed structures can handle
disturbances in feed flowrate and compositions quite well with fairly
small integral absolute error (IAE) values. This work provides novel
control strategy of the VRC-assisted DWC processes and offers a choice
for the energy-efficient distillation applications from the standpoint
of dynamic controllabilities.