Design and optimization of modified non-sharp column configurations for quaternary distillations

•The intensification of non-sharp distillation configuration was considered.•Thermal couplings and section recombination were used as synthesis tools.•Sequences with less than N − 1 columns and divided wall columns were presented.•Design and optimization were performed by means of Aspen Plus and stochastic optimization.•The best intensified configuration selected has 12% reduction in total annual cost.

The possible structural changes of a non-sharp quaternary distillation configuration are considered. For the reference configuration composed of four columns, different alternatives are generated following the process intensification principle to reduce the number of equipment units. The intensified systems with three or two columns are obtained, including the dividing wall columns. Simulator Aspen Plus V8.0 was used to design and simulate all the systems for a hydrocarbon mixture. The intensified structures showed relevant energy savings compared to the reference case. The most promising alternatives were optimized by means of the differential evolution (DE) method minimizing the total annual cost (TAC). It was observed that the intensified systems were able to reduce both the energy consumption and the number of equipment units. The best intensified system has a TAC of 11.98% lower than the optimized reference case.