Schedulability analysis of short-term schedule for crude oil operations using Petri nets

The feasibility of a schedule is essential to the operation of a complex system involving both discrete and continuous processes. This paper studies the short-term scheduling problem for crude oil operations in a control theory perspective. A short-term schedule is composed of a series of operation decisions, each of which can be seen as control. Their execution transfers the system from one state to another. To guarantee a schedule´s feasibility, the system must always be kept in safe states. It is modeled by a Petri net that is under the control of operation decisions. With this model, safeness or schedulability conditions are presented. They reveal the relationship among the number of charging tanks, oil transportation flow rate of the pipeline, and production rate. Based on them, if a refining schedule is found schedulable, a detailed short-term schedule is created as well.