As described before in Section 3.2, the optimization was performed in two steps. First, we added the inequalities described by Equation ( ) and Equation ( ) as constraints to the optimization problem. The algorithm terminated after 41 iterations which took 9.48 seconds. The results are summarized in Table 2. In the table the flow rate ṅ and the concentrations of all product streams are given. Furthermore, we give the values for the heat duty and the liquid and vapor split ratios at the dividing wall l s , v s . The value l s denotes the ratio of liquid that flows to the right of the dividing wall on the top of the dividing wall. The value v s denotes the ratio of vapor that goes to the right side of the dividing wall on the bottom of the dividing wall. The results show that the initial values are a good guess for the optimized values. The initial heat duty is approximately 4% higher than the final heat duty. The vapor and liquid split are smaller than predicted. Which means that in an optimal solution a The smallest flow rate of a product stream is attained for the product stream B.