The influence of the time of the feed introduction on the start-up time can be observed looking at Fig. (scenario ii, Section 2.3.1) and Fig. (scenario iii, Section 2.3.1), which show the temporal evolution of the temperatures inside the column and the product purities for the respective scenarios. For scenario ii (Fig. ), there is a small kink in the evolution TS2 at t = 21 min. Before this kink occurs, a part of the feed, which is at a boiling temperature of around 95 °C, already evaporates and moves to the lower side draw. This leads to an increase in the TS2 and when the vapor eventually arrives at the lower side draw, the slope of the temperature increase steepens. At t = 35 min, all product purities have reached a value of 98 mol%, but xS2 decreases below this value after 47 min, along with a slight decrease in temperature. A possible reason for this behavior is, that the earlier introduction of the feed stream leads to an accumulation of a small amount of middle and light boiling components in the lower part of the column, which needs to again be removed from this part of the column. It takes 166 min until S2 meets the purity specification again, which makes this scenario the one with the overall longest start-up time.