Estimating contamination between batches in products lines

Liquid pipelines are frequently used to transport different products or different grades of the same product. This is achieved through batching the products in a particular sequence within a repeated cycle called the ''batching cycle.'' Factors that affect the overall scheme of batching include pipeline parameters such as flow rate, pipeline length, diameter, equipment, etc.; number of receiving stations along the line and products packages; batch duration and total cycle duration; batching sequence and arrangement; and operating procedure and shutdown periods. The factors also include interface contamination spread handling facilities at terminal points; and storage capacity, the availability of each product at the source end, and its demand at the receiving ends. The feasibility and economics of such operations depend upon the extent of the mixing that takes place between different batches in the pipeline. In this article, a rather general method is described to estimate the extent of the contamination (or mixing) spread, particularly in zones between batches that vary significantly in their physical properties.