Prefractionation is an optional distillation process to separate economic quantities of very light distillates from the crude oil. Lower temperatures and higher pressures are used than in atmospheric distillation. Some process water can be carried over to the prefractionation tower from the desalting process.
Atmospheric distillation breaks the heated crude oil as follows:
1. Light overhead (gaseous) products (C5 and lighter) are separated, as in the case of prefractionation.
Figure 2 Crude desalting (electrostatic desalting). A high-voltage electrostatic field acts to agglomerate dispersed oil droplets for water-oil separation after water wash desalting. (From Ref. 5.)
2. Sidestream distillate cuts of kerosene, heating oil, and gas oil can be separated in a single tower or in a series of topping towers, each tower yielding a successively heavier product stream.
3. Residual or reduced crude oil remains for further refining.
Was this article helpful?