As a first example we consider the separation of the mixture Benzene, Toluene and p-Xylene. The vapor liquid equilibrium is modeled using the NRTL-model. The corresponding parameters are given in Appendix A. As there are three components this mixture can be separated with one dividing wall. We consider a column with a height of 40 theoretical stages. The dividing wall reaches from stage 11 to stage 30. The feed is located on stage 21, where the stages are again counted from bottom to top starting with 1. We consider a feed flow rate of 3 kmol/h and the concentration of each component is 1 3 mol/mol. We assume a constant pressure of 1 bar within the column. We try to minimize the heat duty QR and demand the purities of 0.95 mol/mol in the product streams. The corresponding Petlyuk sequence is shown in Figure . The product streams are denoted by A-C. The streams connecting the different sections of the column are numbered by 1 to 10. We will first present the results obtained with the new approach and then compare them to results obtained with Aspen Plus R as black box simulation software.