The Influence of Pipeline Diameter Variation on the Mixing Volume in Batch Transfers

Presented in this paper is a new model for estimating mixing volumes arising in batch transfers in multiproduct pipelines, when variations of the line diameter as well as injection and/or withdrawal of products are present. Besides these novel features, the model incorporates the flow rate variation with time and the use of a more precise effective dispersion coefficient, which is considered to depend on the concentration. The governing equations of the model form a non-linear initial-value problem that is solved by using a predictor-corrector finite difference method. A comparison among several cases studied reveals that the pipeline diameter variation can effectively reduce the amount of mixing volume when compared to a similar transfer carried out in a constant diameter line.