ABSTRACT
The primary sections of a modern refinery—separation, conversion, and finishing—are described along with the basic process units in a general overview highlighting US and world capacity levels circa 2018. Most of the treatment and conversion processes employ catalysts to enhance the speed of chemical reactions and enhance conversion rates. A refinery performs processes that are often described in simple terms as follows: separation based on molecular size and boiling point; changing the molecular size of components; changing the molecular shape of components; removal of contaminants. Thermal cracking processes such as visbreaking and coking were used to convert heavy fractions into gasoline by thermal decomposition. The purpose of coking is to process heavy residuum to produce distillates that may be catalytically upgraded. By far the most common finishing process in the US and worldwide is hydrotreating, but processes that rearrange and reshape molecules such as reforming, alkylation, and isomerization are also considered finishing operations and are important in refinery economics.
