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Crude Distillation

The first processing step in a refinery operation is Crude Distillation, wherein crude oil is distilled into "rough" fractions.

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)
  • kerosene
  • diesel (or gasoil)
  • residue
To enhance the crude separation process, some pre-conditioning of the crude oil is normally required.

Some examples 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.
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