PURPOSE: To enable the reduction in residual amount of chlorine in an atmospheric distillation step and, thereafter, prevent the corrosion and enable the stable operation of a crude oil refiner by mixing specific wash water with a crude oil, separating the resultant mixture into an oily layer and a water layer, recovering the crude oil and efficiently carrying out the desalting of the crude oil.
CONSTITUTION: Wash water containing an alkaline compound in an amount of-0.5-2.5 equiv. based on the amount obtained by subtracting the chlorine content equiv. corresponding to the total content of an alkali(ne earth) metal contained in a crude oil from the total chlorine content equiv. in the crude oil is mixed with the crude oil and the resultant mixture is then separated into an oily layer and a water layer to recover the crude oil. Thereby, the crude oil is desalted. Furthermore, the alkaline compound in the wash water is preferably an alkaline metallic hydroxide and the concentration thereof is preferably 0.001-0.01 N.
OHASHI MITSUHIRO
IWANAMI KIYOTAKA