(518d) Computational Studies of Flushing Dynamics during Product Changeovers in Multi-Product Pipelines

Product integrity is crucial in the management of multiproduct pipelines in the oil and petrochemical industries. These pipelines, characterized by a complex network of interconnected pipes, are employed for the processing of a wide range of oil products with varying physical properties. A significant challenge in the operation of such pipelines is the changeover process, where residual oils from previous batches must be flushed out before introducing a new product [1]. This process is complicated by the formation of a three-layered zone within the pipeline, consisting of the leaving residual oils, a mixed section of blended oils, and the flushing oil entering the system [2]. The presence of these zones necessitates the use of large volumes of flush oil to effectively displace the residual and mixed oils, thereby impacting the efficiency and economics of the operation.

This study presents a comprehensive experimental and numerical investigation of the flushing process in miscible but dissimilar oil systems using a scaled-down pilot plant that mimics the industrial multiproduct packaging lines. We have developed a numerical model that simulates the flushing process through mass and momentum balances, incorporating the effects of dispersion and diffusion of residual oils from the pipeline walls into the core of the flushing fluid. The model aims to estimate the volume of residual oil entrapped prior to each product changeover and to determine the length of the mixed sections. By accurately estimating the length of the mixed section, we can achieve precise control over process variables, thereby enhancing the efficiency of the flushing operation and reducing the amount of flush oil required.

Our experimental approach utilizes targeted experimentation in the pilot plant for each product changeover category, which is devoid of sampling, due to the installation of an inline viscometer for real-time measurement of oil viscosity. This setup allows for continuous monitoring of the flushing process and provides valuable data for validating and refining the numerical model. By combining experimental insights with the predictive capabilities of the model, we aim to develop an optimized flushing operation that minimizes the formation of mixed sections and reduces the volume of flushing oil (new product) needed for each product changeover.

The significance of this work lies in its potential to improve the operational efficiency and sustainability of multiproduct pipeline systems. By reducing the volume of flushing oil required, we can decrease operational costs and minimize environmental impact. Furthermore, the enhanced control over the flushing process ensures better product integrity and quality, which is paramount in the oil and petrochemical industries. Our study provides a holistic approach to addressing the challenges of product changeover operations in multiproduct pipelines, combining experimental investigation with advanced numerical modeling to offer practical solutions to industry practitioners.

References

[1] 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.

[2] 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.