Minimization of Commingled Product in Pipeline Flushing Operations

When petroleum-based lubricants are packaged, it is necessary to separate products based on their physical properties and customer requirements to avoid cross contamination. This complicated network of pipes cannot be cleared using traditional methods such as using a piping inspection gauge (PIG). The most simplistic method for clearing out these sections of pipe is to flush finished product through the lines. This solution is effective in preparing the pipeline for the next product, but it generates large quantities of downgraded products (commingled oils) that must be sold at a lower price. The goal of this work is to reduce the overall quantity of oil flushed through a pipeline, while still maintaining product integrity. Our project highlights different ways that production plants can reduce the volume of oil flushed through procedural changes, hardware changes, and predictive modeling. These changes can be implemented in a variety of circumstances such as packaging plants that prioritize reducing capital costs, plants that are willing to invest in production line upgrades, and plants that are currently being designed. Potential solutions include introducing procedural changes in packaging operations, retrofitting existing pipelines with filters that trap less residual product, and designing pipeline systems with oleophobic coatings, reduced size filters, and improved pipe pathing. Procedural changes have been shown to reduce the quantity of commingled product generated at both a lab scale, and at production scale. By mimicking the piping and instrumentation of production plants at a lab scale, our group has gained insights into how changes in piping and instrumentation affects the required flushing volume. A critical component of this project is modeling a system to predict the mass fraction of a residual product in a pipeline after flushing for a set time. This model will allow operators to reduce the quantity of lubricant product that becomes downgraded. In this work, we were able to predict and justify procedural changes that can lead to significant volume and cost savings by improvement in flushing practices at these facilities.