(295c) A Fundamental Convective-Diffusion Based Model to Explain Interfacial Mixing In Multiproduct Pipelines

Interfacial contamination of batches of refined petroleum products transported through multiproduct pipelines is a long standing problem in the petroleum industry.  Determination of the extent of mixing depends on various factors including the fluid properties, operating conditions and the flow regimes.  The convective-diffusion model along with a fictional parameter introduced by Sir G. I. Taylor, known as the axial dispersion coefficient is the commonly employed methodology to evaluate this system.  However, the system is formulated with a uniform turbulent or laminar flow across the entire flow field.  This study argues that the assumption of a uniform flow regime leads to inaccuracies in predicting the extent of contamination at the interface.  This study incorporates both the turbulent and the viscous effects in predicting the interfacial contamination volume.  Taylor’s analysis of dispersion coefficients has been reviewed and an improved model combining the weighted effects of the viscous boundary layer contributions and the turbulent core contributions to axial dispersion has been proposed.  A comparison of the present model with literature data reveals that considering the effect of both the turbulent and the viscous effects result in better overall prediction accuracy, while laying a foundation to explain the underlying physics.