Abstract
Distillation is one of the most energy intensive process in the chemical industry. To efficiently utilize the energy supplied, various modifications can be made to the process. One of the demonstration of such modifications is the divided wall column (DWC). Presence of the additional wall partition in a DWC increases the design degree of freedom which affects the required energy consumption significantly. Liquid split can be easily controlled during operation and its implementation has been successfully demonstrated in many literatures. On the other hand, practical means of utilizing vapor split ratio is rather limited from the literature and it is often limited to the location of the partition wall. Considering hydrodynamic conditions, we shall investigate the possibility of dynamic energy minimization through indirect vapor split manipulation. To show its effectiveness, comparison with conventional control structures has been made. Indirect vapor split control is possible by floating the operating pressure of a DWC with upper partition (DWCU) in a controlled manner. In the case of a DWC with middle partition (DWCM), internal heat exchangers were added but it has little effect on changing vapor split ratio. For both DWCU and DWCM, our proposed modifications to the conventional control structures are able to reduce the reboiler demand without requiring major modifications made to the DWC system.