The processes of dehydration, desalting and the stabilization of oil are carried out at complex oil preparation unit.
Cold «crude» oil from the tanks is directed through the heat exchanger into the settler of continuous action by pump. Here the most part of the mineralized water settles on the bottom of the apparatus and is drained for further preparation in order to pump in the layer. Then fresh water is introduced into the flow to reduce the concentration of salt in the remaining mineralized water. The final water separation from oil takes place in the electrical dehydrator and dry oil is delivered through a heat exchanger to the rectifier. Due to the pumping oil from the bottom of the column through the furnace by pump its temperature is brought up to 240°С.
Light oil fractions are evaporated, rise to the top of the column and then come in the condenser-cooler. Here the propane-butane and pentane fractions are mainly condensed, forming the so-called wide spread and non-condensed components are removed for use as a fuel. The wide spread is pumped out by the pump for fractionation and is partially used for the reflux in the column .
There are some processes in the complex oil preparation unit: dehydration, desalting and oil stabilization. And as for dehydration, heating, settling and electrical action are used at the same time, i.e. a combination of several methods .