Product mixing occurs often in batched liquid-phase pipelines. If not successfully mitigated, this can result in a product being assigned as a less valuable one at the terminal end, leading to a significant financial impact. There is also risk of contamination of one product with an impurity the other product is carrying, especially in cases where the product thermodynamic properties are very similar. Current methods for calculating interface volume, for example, Austin & Palfrey 1963, do not appear to scale-up accurately in a consistent manner from the lab to the pipeline. This paper presents a technique for determining the diffusion coefficient in the differential equation for diffusion transport in a pipeline, based on actual measured data. The transport equation was made non-dimensional and the Laplace Transform solution approach was applied; the inverse Laplace Transform was determined using an analytical method. The diffusion coefficient was then deduced from actual pipeline densitometer measurements by varying the coefficient to obtain an acceptable fit to the data. Continued application of this approach should result in a database of coefficients that can be applied to a particular flowing scenario.

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