(184aa) Simultaneous Scheduling of Refinery Manufacturing and Pipeline-Based Multi-Oil Product Distribution

Refinery manufacturing and product distribution systems are highly correlated in the entire refinery supply chain. If they were handled separately, it may cause imbalances or discrepancies between the production and distribution sectors, and thus the loss of the profit margin across the refinery supply chain. On the contrary, the optimal coordination between these two systems could benefit not only the industrial profitability, but also the reduction of both management risks. For instances, based on stable oil products from refineries, inventories of distribution center could be kept in a reasonable lower level to reduce the distribution cost; meanwhile, based on a reliable demand from distribution center, the refinery could conduct a need-based production to avoid unnecessary overproduction. Therefore, refinery manufacturing and product distribution should be and could be optimally integrated if at any possibility. Certainly, such simultaneous scheduling work present a grand challenge to refiners.

Many published studies have addressed refinery production and pipeline distribution system separately, while only a few works have addressed two sectors simultaneously. Existing publications either focused on the strategic and tactical decision level for the upstream and midstream (Azadeh et al., 2017), or sequentially and 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 a detailed continuous-time and continuous-slot scheduling with long-distance pipeline system. In this work, a continuous-time based integrated MINLP model is developed to optimize the scheduling of both refinery manufacturing operation and multi-oil product distribution. The general objective is to maximize the total profit; meanwhile, operation and product specifications, inventory limits, transportation constraints and production demands have to be satisfied. The scope of this work includes two main parts: refinery and long-distance pipeline distribution system. The refinery includes crude distillation, reforming, cracking, hydrotreating, blending, gas processing, and sulfur recovering facilities. The long-distance pipeline distribution system connecting the refinery plant and multiple depots, which transport multi-oil product to different marketing areas. Each depot contains various oil-product storage tanks and mixing tanks dedicated to hold pure products and mixtures respectively. A lot of realistic features such as feed and product blending, multiple depots receiving oil product simultaneously, brine settling time, and interface mixing between two kinds of products inside pipeline have been modelled or constrained. Overall, the simultaneous scheduling model could provide optimal solutions such as processing stream property and flowrate for unit operations, yield and inventory of various petrochemical products, product movements inside pipeline, as well as oil product discharging rate to multiple depot tanks based on consumer demands. The efficacy of the developed integrated scheduling model is demonstrated by a detailed case study.

References

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

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

Tong, K., Feng, Y., Rong, G., 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.