High-quality blend scheduling solution for sizing, selecting, sequencing, slotting and spotting in the processing industries

High-quality process system engineering (PSE) solutions for production scheduling evolve to a wider scope and scale when moving from simulation- to optimization-based approaches, generally by using mixed-integer programming (MIP) in discrete-time formulations. To reach as we state in this paper as the spotting level of service, into the scheduling operational details and time-step within a time-horizon of planning, the novel aspect of these types of PSE solutions is to integrate automated logistics or blend logistics decisions regarding: (1) sizing the future blend volumes for blending (or throughputs of unit-operations for processing); (2) selecting a product tank for the blends (or modes of operation for the process units); (3) sequencing the blended product grades (i.e., regular before premium, etc.) in multi-product blender (or the sequence of modes of operation for units/tanks); (4) slotting the start-times of the blends (or processing-time of units) into time-periods; and (5) spotting the future product shipments to steward to the plan. Examples of scheduling optimization effectively implemented are: (1) the production of lubes and asphalts with sequence-dependent switchovers between modes of operation; and (2) the gasoline blend scheduling operations using decomposition strategies and cuts based on nominal qualities. Faster results are obtained by tailored solutions of decomposing these industrial problems.