The first processing step in a
refinery operation is Crude Distillation, wherein crude oil is distilled into
The terms commonly used for this operation are:
- CDU (Crude Distillation Unit)
- ADU (Atmospheric Distillation Unit)
In simple terms, the crude oil is normally pumped
through a series of heat exchangers, into a distillation column. The
distillation column splits the crude oil into "rough" fractions or cuts. A
typical set of cuts from this operation is:
- inerts, gas and light ends (naphtha)
- diesel (or gasoil)
To enhance the crude separation process, some
pre-conditioning of the crude oil is normally required.
of this are
- Desalting, where the salt (solids) content of the crude
oil stream is reduced
- Pre-Heating, which involves the use of heat exchangers
to increase the temperature of the crude oil stream, and
- Vaporising, which is typically done using a fired
heater, which is located directly in front of the distillation column.
Typically, crude oil distillation is performed at a
pressure of 0 - 5 barg. The temperature and pressure profile of the
distillation column is selected to ensure the maximum separation efficiency to
give the required products.
The resultant fractions or cuts are taken
as products from the crude distillation section for further processing in
downstream refinery units.