(195b) Multi-Oil Product Pipeline Scheduling with Appropriate Handling of Oil Mixing Interface

Pipeline is more efficient and reliable to transfer large amounts of petroleum products than other ways via road, railroad, and vessel. To save capital and operating costs, one pipeline needs to transfer different types of oil products to different oil depots according to their ordinary demands. As two different consecutive oil products inside a pipeline will not be separated by a physical divider, the product mixing is inevitable near the interface of two oil products. To guarantee the oil quality adopted by storage tanks at depots, a considerable amount of mixing oil product from the pipeline needs to be dealt with properly at depots. In practice, three kinds of methods are used. The first one is to blend mixture oils into pure product, which might have some oil quality problems; the second one is to separate the oil mixture into pure oil products through distillation; and the third one is the hybrid method coupling the former two methods together. Conceivably, the multiproduct pipeline scheduling problem with consideration of dealing with oil mixing inside the pipeline present a very challenging problem to industries. There are few works reported in this area (e.g., Rejowski et al. (2003); Cafaro and Cerdá (2004 and 2010)). However, they still lack studies on dealing with the oil mixture product.

In this work, a continuous-time based MILP model is developed to optimize the transportation and distribution of multi oil products, which includes a long-distance pipeline, several depots with storage tanks and mixing tanks dedicated to hold pure product and mixture respectively. The oil mixing interface inside the pipeline is modeled as three parts: two product-rich mixing parts on both sides of the mixing interface and one well mixing part in the middle. The hybrid method for blending product-rich mixture into the pure product and refining the well mixing mixture has been adopted. Overall, the scheduling model could provide optimal solutions including product feeding into pipeline, product movements inside pipeline, discharging product to multiple depot tanks, as well as sending out oil product based on consumer demands in the continuous time formulation base. The efficacy of the developed scheduling model is demonstrated by multiple case studies.

Keywords: Multiproduct Scheduling, Pipeline, Mixing Product Management, MILP

References:

Cafaro, D., & Cerdá, J. (2004). Optimal scheduling of multiproduct pipeline systems using a non-discrete MILP formulation. Computers and Chemical Engineer- ing, 28, 2053–2068. ISSN 0098-1354.

Cafaro, D., & Cerdá, J. (2010). Operational scheduling of refined products pipeline networks with simultaneous batch injections. Computers and Chemical Engineer- ing, 34, 1687–1704 .

Rejowski, R., & Pinto, J. (2003). Scheduling of a multiproduct pipeline system. Com- puters and Chemical Engineering, 27, 1229–1268 .