An Overview of Models and Solution Methods for Pooling Problems

Network flow models, where the flow quality is given at the supply nodes and quality constraints are defined at the demand nodes, appear frequently when optimizing refinery operations, pipeline gas transportation, and other energy related operations. Tracing the quality of the flow from the supplier to the market implies that the quality must be updated at the nodes where different flow streams are mixed. This results in the well-known pooling problem, the non-linear nature of which makes it hard to solve. In this chapter, I give an overview of available methodology for solving the pooling problem. I distinguish between fast but possibly inexact methods aimed for medium and large scale instances, and more time-consuming exact methods that tackle small instances.