Rohöldestillation

Rohöldestillation is a foundational unit operation in petroleum refining in which crude oil is heated and separated into fractions according to boiling point. The process usually begins with pretreatment to remove water and inorganic contaminants, after which the crude is heated and fed to an atmospheric distillation column. Inside the column, vapors rise and cool, so components with lower boiling points condense higher in the column and are withdrawn as light products, while heavier fractions condense lower down. Typical top products include LPG and naphtha; mid-range cuts are kerosene and diesel; the bottom product is heavy residue.

The atmospheric distillation yields are subsequently split and routed to downstream units for further refinement. Heavy residues may be processed in a vacuum distillation unit, which operates at reduced pressure to allow distillation of heavier components at lower temperatures. This stage can produce additional gas oil and lubricating oil streams, while leaving a vacuum residue or asphalt.

The specific yields depend on the crude oil's composition, including API gravity, sulfur and metals content. Rohöldestillation is the first step of the refining process and largely determines the amounts of gasoline, diesel, jet fuel, and other products that a refinery can produce. After distillation, the fractions are usually subjected to further processing such as hydrotreating, reforming, cracking, or blending to meet product specifications.

Historically, atmospheric and vacuum distillation have been standard in refineries since the early 20th century, with improvements in column design, heat exchange, and control systems increasing efficiency and safety.