The two types of impurities preset in crude oil. The impurities which can be removed by electrical desalting are called as “Oleophobic” means lacking an affinity for oil. Oleophobic constituents are insoluble in crude oil and are present as a second phase, being carried as discrete particles by the oil.
Examples of Oleophobic Impurities in crude oil are;
Salts, range 10~1000 PTB
Water, 0.1~2 vol %
Sediments,1~ 500 PTB.
The second class of impurity is known as “Oleophilic” impurity (having a strong affinity for oil). Oleophilic impurities are soluble in crude oil and cannot be effectively removed by electrical desalting methods. Typical constituents of this type may be listed as follows:
Sulfur Compounds 0.1~5 wt %
Organo-Metallic Compounds (Nickel, Vanadium, Iron, Arsenic, etc.), 5~500 ppm as metal.
Naphthenic Acids, 0.02~0.5 Vol.%
Nitrogen Compounds, 0.06~15 Vol.%
Non-Acidic Oxygen Compounds
(Resin, Cresols, etc.), 0 – 2 Wt.% as oxygen