(117d) Integrated Scheduling for Midstream and Downstream of Oil Refinery Supply Chain

Crude oil uploading, transfer, manufacturing, and oil-product distribution systems are critical operations and highly correlated in the entire oil refinery supply chain. However, very few efforts have focused on the integrated scheduling for the midstream and downstream of oil refinery supply chain. If they were scheduled separately, imbalances or discrepancies between the crude transfer, production and distribution sectors may happen, thus the loss of the profit margin across the refinery supply chain. On the contrary, the optimal coordination of these three systems could benefit not only the industrial profitability, but also the reduction of both management risks. Many published studies have addressed crude transfer, refinery production and pipeline distribution systems separately, while only a few works have addressed two or three sectors simultaneously. Existing publications either focused on the strategic and tactical decision level for the upstream and midstream of crude oil supply chain (Azadeh et al., 2017), or simply considered the scheduling problem with a discrete framework (Guyonnet et al., 2009, Tong et al., 2012). However, there is still lack of the systematic and integrated study dealing with the continuous-time and continuous-slug based extremely large-scale refinery supply chain problem.

In this work, a new continuous-time based integrated MINLP model is developed to optimize the scheduling of crude unloading and transfer, refinery manufacturing operation and multi-product pipeline distribution. The scheduling objective is to minimize the total operating cost; meanwhile, operating rules and product specifications, inventory limits, delivery constraints and oil product demands must be satisfied. The scope of this work contains crude unloading and transfer, refinery processing and multi-product pipeline distribution system. The crude unloading and transfer system includes vessels, storage tanks and charging tanks. The refinery includes crude distillation, reforming, cracking, hydrotreating, blending, gas processing, and sulfur recovering facilities. The long-distance pipeline distribution system connecting the refinery tank farm and multiple depots, which transport oil products to different local markets. Overall, the integrated simultaneously scheduling model could provide optimal solutions such as crude vessels unloading, crude transfer profiles, processing stream property and flowrate for unit operations, yield and inventory of various petrochemical products, injection sequence and volume of new batches, oil slugs movement inside pipeline, as well as oil product discharging to multiple depot tanks based on consumer demands. The efficacy of the developed integrated scheduling model is demonstrated by an industrial scale study.

Keywords: Simultaneous scheduling, Crude unloading, Crude transfer, Refinery manufacturing, Multi-product, Pipeline distribution, MINLP

References

Azadeh, A., Shafiee, F., Yazdanparast, R., Heydari J., and Keshvarparast, A. (2017). Optimum Integrated Design of Crude Oil Supply Chain by a Unique Mixed Integer Nonlinear Programming Model. Industrial & Engineering Chemistry Research, 56: 5734−5746.

Guyonnet, P., Grant, F.H., Bagajewicz, M.J. (2009). Integrated Model for Refinery Planning, Oil Procuring, and Product Distribution. Industrial & Engineering Chemistry Research, 48: 463–482

Tong, K., Feng, Y., Rong, G. (2012). Integrated Model for Refinery Production and Pipeline System Scheduling. Proceedings of the 22nd European Symposium on Computer Aided Process Engineering, 17 - 20 June 2012, London.