Intensified process for aromatics separation powered by Kaibel and dividing-wall columns

Abstract Process intensification in distillation led to major developments, such as reactive distillation, heat-integrated distillation, cyclic distillation, as well as Kaibel and dividing-wall column. Still, the separation of aromatics at industrial scale is carried out typically in a series of conventional distillation columns, with severe penalties on the associated plant footprint, investment and operating costs. To solve this problem, this study investigates novel separation alternatives powered by dividing-wall column (DWC) and Kaibel distillation column. The new sequences using process intensification are able to separate five products (lights, benzene, toluene, xylene and heavies) at high purity levels, in only two distillation columns. AspenTech Aspen Plus ® was used as a computer aided process engineering tool to perform the rigorous simulation and optimization of the new separation alternatives, applied to a simplified industrial case study. In order to allow a fair comparison, all design alternatives were optimized using the sequential quadratic programming (SQP) method. Notably, the novel design with two consecutive DWC units reduces the energy demand by 14%, while the alternative combining a conventional stripper with a Kaibel column leads to over 17% energy savings as compared to the conventional direct distillation sequence. Moreover, the new separation schemes require less equipment and a reduced plant footprint.