Process towers or columns are used in the distillation process. Distillation is widely used in the chemical process and refining industries. In petroleum refineries, crude oil is distilled to extract different monomers that are required for fuels and distillates. These distillates are used in many applications including the production of plastics.

Industrial distillation is typically performed in vertical cylindrical towers or columns known as "distillation towers" or "distillation columns". These columns are designed and operated to produce varying streams according to the output streams boiling point.

These columns are typically equipped with internal trays to deflect the upward flow of the boiling fluid. There are several types of trays designed to accomplish different flow characteristics. They include Bubble-cap trays, valve trays, and sieve trays.