Dynamic Scheduling Research And System Development On Oil Refining

With the technicalization, high-integration, management-complication and coordination of industry production, production scheduling system, as the command center of process control and management, is becoming more and more important. Production scheduling is to allocate resources reasonably in the given time, aimed to achieve the predetermined production target. Production scheduling problem has been shown to be a NP complete problem.To solve production scheduling problem, many methods are used, among which establishing mathematical model is in widespread use, and it is the best up to now. However, because of the complication of the objective production environment, the traditional method of establishing mathematical programming model is hard to meet the challenge with real-time requirement of dynamic scheduling, and this is also one of the main reasons why production scheduling system is seldom used in oil refineries.In this article, a new modeling method based on event logic is adopted to satisfy the real-time requirement of dynamic scheduling, and the steps are as follows:1) Analyze technics of refining process.2) Define and describe events.3) Generate event logics according to event descriptions.4) Establish a flow scheduling model and a event model based on the event logics.5) Construct the dynamic scheduling model by combining the flow scheduling model and event model together.This method can raise the rapidity and flexibility of establishing the dynamic scheduling model and the practicability of scheduling optimization theory, solve the tough work of rapid modeling in refineries to some extent and get a relatively better scheduling result.Based on the above-mentioned method, a dynamic scheduling model is constructed and a corresponding dynamic scheduling system is developed for oil refineries, and its functions are as follows:1) Graphically build the flow configuration model for an oil refinery.2) Create event definition and prediction scheme description for an emergency.3) Construct the dynamic scheduling model for the emergency based on the flow configuration model, and solve the model by use of Lindo API.4) According to the scheduling results obtained in step 3, conduct production simulation for the whole plant to verify the validity of the scheduling results.The successful simulation application of the dynamic scheduling system in oil refineries indicates that the modeling method based on event logic is effective and the dynamic scheduling model above-mentioned is reasonable.