Hereby, if the high-pressurized step, in particular, is "repeated" after its feed tank is filled with the additional charge, a more complex pattern is for the optimal control structure. In the second step, ie. high-pressurized process, as supposed the initial arc match with zero distillate rate (total reflux condition-stripper), but the final with maximal distillate rate. Further, it is observed that the optimal control trajectory is composed of almost all bang-bang arcs, with three consecutive singular arcs preceding the final maximal distillate arc. There are 30 commutations between different types of control, since the three instantaneous piques achieving maximum distillate rate, are not taken into the consideration due to the extremely short period of duration. An interesting fact is that the singular arc(s) are 'positioned' again in the penultimate period, whereas here it lasts approximately 7% of the total operation time or 8 times shorter than in an LP step. The initial zero arcs is of the longest duration, as it takes almost 40% of the operation time. In summary, the optimal control has 15 bang arcs, 15 zero arcs, and three singular arcs (Figure ). The working conditions, and, optimal costs with recoveries, are tabulated in Table , respectively. All the more, keeping the first/second vacuum pressure constant, and increasing the higher pressure in the second part of the process for not more than 10%, brings an improvement of 16%/17.37%, respectively, in the yield. From the aspect of profit, one should consider the first option as a more profitable one. All optimal control policy patterns are "near-BB" or "BB" (one short and pre-ultimate singular arc). It is to note that all the calculations are done for the "single period" duration of the high-pressurized step, ie total batch time is set to a "single-period" of time.