Petri net-based approach to short-term scheduling of crude oil operations with less tank requirement

Abstract

With the interaction of discrete-event and continuous processes, the short-term scheduling problem of crude oil operations is essentially combinatorial. Thus, it is preferred to develop computationally efficient techniques for a satisfactory solution other than an exactly optimal one. Based on this idea, such a scheduling issue is studied in the viewpoint of control theory. To do so, as charging tanks are a type of critical resources, it is crucial to determine how many charging tanks are required to obtain a feasible schedule. By using a hybrid Petri net to describe the behavior of crude oil operations, we show that a feasible schedule can be found for a system with two or more than two distillers if there are two charging tanks for each distiller, which is the least number of charging tanks for finding a feasible solution to reach the maximal productivity. Also, the requirements of the initial state for obtaining a feasible schedule are given and scheduling method is proposed. The scheduling method is simple and computationally efficient. An industrial case study is used to show how the proposed approach can be applied.