473931 A Unified Planning and Scheduling Platform for Refining Operations
Traditionally the functions of refinery planning and scheduling are separated both in terms of business organization structure as well as processes and technologies employed. Planning is typically done using a commercial optimization tool (such as Aspen PIMS) and executed by the economics planning function. Scheduling on the other hand, is done using primarily simulation-based tools at the refinery level (such as Aspen Petroleum Scheduler) augmented by optimization tools at the product blending level (such as Aspen MBO). This practice creates a disconnected set of workflows that primarily create an overly optimistic plan that is not constraint by detailed scheduling considerations. As a result, there is a mismatch between the plan and the schedule constraints that leaves a significant set of benefits unrealized. This is known in the refining industry as a margin leak.
In this paper, we review the main challenges in unifying refinery planning and scheduling and propose a framework for addressing those challenges. We also show the necessary key attributes for the new modeling and analysis environment and demonstrate how they can be brought together to enable the combined optimization of planning and scheduling.