The dewatering process is based on the destabilization of water-in-crude oil emulsions.
Basic dewatering and desalting methods in use today can be provisionally divided into mechanical, chemical, and electrical. All these methods are aimed at different techniques promoting the growth of water droplets and their separation from crude.
The most efficient crude oil dewatering and desalting equipment is electric dehydrators. In a dehydrator, demulsification is performed in an AC electrical field.
An electric dehydrator of any type consists of a vessel in which electrodes are suspended on insulators, a device for emulsion introduction and distribution and discharge of oil and water after separation. The power is supplied to the electrodes from a dedicated HV transformer. In the inter-electrodes space, the high voltage electrical fields induces water droplets coalescence so that they can be separated by gravity and descend to the bottom of the vessel. The emulgator film, enveloping water droplets, is destroyed by the injection of a demulsifying agent into emulsion.
For a complete dewatering, oil emulsion passes through the electrodes system. In parallel, desalting of oil emulsion is performed.