In the subsequent steps, both strategies differ. According to the discontinuous strategy, the column is operated at total reflux. As soon as the temperature profile inside the column is constant, first the distillate valve is opened to withdraw component A at the steady state flow rate. The withdrawal happens in intervals. An interval ends when the temperature at the top product draw starts to increase. Between each step of product withdrawal, the temperature profile inside the column needs to stabilize again. As component A is withdrawn at the top, component B can move up in the column. When the mole fraction of B at the upper side draw S1 reaches the specified purity, the withdrawal of A is complete, and the distillate valve is closed. Analogously to the withdrawal of A, component B is withdrawn as upper side product (S1), and component C is withdrawn as lower side product (S2).