US Complex refining capacity leads the world and US Gulf Coast refineries are enjoying an export led boom. As lower cost crude starts to become available to these refineries they should be in a strong position to compete even more efficiently in global markets. What makes these complex refineries competitive? Today we conclude our two part refining tutorial by explaining refinery upgrading processes.
If you haven’t already read the first part of this tutorial then you can review it here. In Part 1 we provided an overview of the refining process described the fractions that make up crude oil and ran through the refined product outputs of a complex refinery. We looked at the first refinery process – atmospheric distillation that breaks crude down into its component fractions. Today we turn to the processes refiners use to upgrade the heavier residual fuel oil outputs from atmospheric distillation.
Refinery Upgrade Processes
The first refinery upgrade process after atmospheric distillation involves reprocessing the residual oil (a.k.a. resid or bottoms) that comes out of atmospheric distillation. In a simple refinery, this residual oil would be sold as heavy fuel oil – perhaps to a shipping company or a power generator. The value of such heavy oil is often lower than the crude oil it was made from. Some overseas refineries sell their fuel oil to complex refineries that can then put the oil through the upgrading process we are describing here. That fuel oil is known as “straight run” fuel oil – because it just ran straight through atmospheric distillation.
The first upgrade process is to run the residual oil through a vacuum distillation unit (see diagram below).