Efficient Decomposition Approach for Large-Scale Refinery Scheduling

This paper proposes a heuristic algorithm for integrated scheduling of refinery production unit operations and finished product blending and delivery operations. To apply the proposed iterative algorithm, the integrated oil-refinery scheduling problem is decomposed into a production unit scheduling problem and a finished product blending and delivery scheduling problem. The goal of the algorithm is to obtain a feasible solution that satisfies product demand commitments with minimum demurrage violations while minimizing run-mode changeover cost, inventory cost, and penalties subject to product and logistics giveaways. The proposed algorithm provides a feasible solution at the end of each iteration, and to obtain solution without demurrage violations, a set of integer cuts are generated at the end of an iteration to eliminate current task assignment sequence for a multipurpose blend unit. The applicability of the algorithm is illustrated by a realistic large-scale refinery case study producing diesel and jet fuel. Significant savings are realized in the computational effort.