After this first run we dropped the additional inequalities and optimized again starting from the solution found so far. The algorithm terminated after 16 additional iterations which took 4.27 seconds. The results are also shown in Table . As removing an additional inequality increases the size of the search space, a better solution is found in the second step. One can see in the table that the flow rate at the top stream becomes a little bit smaller and the purity of the head-product increases. The split ratios differ slightly, the difference in the heat duty is almost negligible. This means that both solutions differ not too much and the solution found in the first step is a good starting point for the second step in which the full search space is explored.