Distillation columns is one of the most energy intensive equipment in chemical and petroleum industries.

The separation of ternary mixtures usually is accomplished by the classical sequence of two distillation columns. Interestingly, according to Ling e Luyben (2009), the Divided-Wall Columns (DWC) can reduce the energy costs in up to 30%. Besides lower operational costs, this configuration can also reduce capital costs.

In the iiSE process simulator, DWCs can be simulated and optimized using both two columns (a prefractionator and a main column) and four columns. Check the example “BTX Divided Wall” for a simulation case using four different columns to simulate this process:

Using the DWC configuration, according to the above simulation, the reboiling duty is around 38 MW. The classical sequence requires around 54 MW heat duty total: