This transition typically results in the formation of a three-layered zone: (i) the leading residual zone, which consists of the leftover oil from previous batch; (ii) the commingled zone, which is a blend of the residual oil and the new oil; and lastly (iii) the flush oil zone, which is at the forefront of the pipeline [3]. Managing these zones effectively is crucial to prevent compromising product integrity. The commingling results in downgraded oil, which is of limited value and use, hence, industry wants to minimize the commingled oil formation, which in our work translates to minimizing the commingled zone. However, current practices relies on trial and error, based on prior experience and operator discretion leading to higher volumes of flush, product downgrade, economic losses, and environmental concerns.
This study presents a systematic experimental investigation of the flushing operation in a pilot plant that we designed and constructed to mimic the industrial plant. We investigate two flushing strategies: (i) direct oil-to-oil flushing, in which a plug of fresh oil is introduced to displace the residual oil, and (ii) air-blowing followed by flushing, where compressed air is initially introduced to remove most of the residual oil before introducing the fresh oil. The key performance metric is the product viscosity, which is continuously monitored using an inline viscometer and a real-time data acquisition system. By tracking the viscosity changes from the residual oil through the commingled phase to the final product phase, we can determine the precise moment when desired product specifications are met. The same oils products are tested for both flushing strategies. The volume of oil required to achieve desired product purity within a of the flush oil viscosity is used as a metric to assess the effectiveness of these flushing strategies.
Additionally, we investigate and develop correlations for flushing time by normalizing viscosity readings over time. Our experiments span multiple oils categorized by their viscosity ranges, allowing us to analyze different fluid interactions. This research addresses the inefficiencies of traditional flushing processes and provides data-driven guidelines for minimizing oil usage while maintaining product integrity. By refining the flushing process, we aim to reduce oil usage for flushing, lower operational cost, enhance environmental sustainability and improve overall operational efficiency. These improvements will ultimately lead to better control over multiproduct pipeline operations, ensuring both economic and environmental benefits for the petroleum and petrochemical industries.
References
[1] B. Gao et al., “Improved Design of Flushing Process for Multi-Product Pipelines,” presented at the Foundations of Computer-Aided Process Design, Breckenridge, Colorado, USA, Jul. 2024, pp. 137–144. doi: 10.69997/sct.171679.
[2] S. S. Jerpoth, R. Hesketh, C. S. Slater, M. J. Savelski, and K. M. Yenkie, “Strategic Optimization of the Flushing Operations in Lubricant Manufacturing and Packaging Facilities,” ACS Omega, vol. 8, no. 41, pp. 38288–38300, Oct. 2023, doi: 10.1021/acsomega.3c04668.
[3] G. He, N. Yang, K. Liao, B. Wang, and L. Sun, “A Novel Numerical Model for Simulating the Quantity of Tailing Oil in the Mixed Segment between Two Batches in Product Pipelines,” Math. Probl. Eng., vol. 2019, pp. 1–14, Aug. 2019, doi: 10.1155/2019/6892915.