Refinery Optimization Integrated with a Nonlinear Crude Distillation Unit Model

In this paper, the problem of optimal crude oil procurement combined with refinery operations is addressed to obtain an ɛ–global optimal solution. Rather than the traditional planning and scheduling methodologies relying on linear programming (LP), a nonlinear model using Geddes fractional index (FI) is employed to describe the behavior of the crude distillation unit (CDU) and integrated with the entire plant-wide model. Although this representation provides more accurate prediction of the real production of the refinery than the conventional fixed yield approach, its global optimization becomes more difficult owing to the existence of many nonlinear, non-convex terms. To overcome this challenge, advanced interval reduction techniques are developed and combined with state-of-the-art global optimization software to obtain an e–global optimal solution more efficiently. The optimization and comparison are conducted to show the effectiveness of the proposed approach.