Petroleum Desalting Utilizing Voltage Modulation

Abstract

A method of removing entrained salt containing water from an inlet crude oil stream includes the steps of applying an electrical energy to at least one electrode of a plurality of horizontally oriented, spaced-apart electrodes ( 12, 14, 16 ) housed within an elongated desalting vessel ( 10 ) and distributing an inlet crude oil stream between the electrodes. Each electrode in the plurality of electrodes is housed in an upper portion of the desalting vessel and may be in communication with a first, second and third transformer ( 42, 44, 46 ), respectively. The electrical energy may be at a single frequency and voltage or at a modulated voltage. Or, the electrical energy may be a modulated frequency at a single or modulated voltage. Fresh water may be mixed with the inlet crude oil stream either exteriorly or interiorly of the vessel.

What is claimed is: 
     
         1 . An elongated horizontal vessel comprising:
 a lower, an upper, and a middle electrode, each electrode oriented in a horizontal plane and sharing a same vertical plane;   at least one transformer in communication with at least one of the lower, upper and middle electrodes;   a vertically oriented pipe in communication with a crude oil stream inlet;   the at least one transformer providing an electrical energy having a frequency greater than 60 Hz;   the vertically oriented pipe having means for horizontally distributing a crude oil stream between the lower and middle electrode and the middle and upper electrode.   
     
     
         2 . An elongated horizontal vessel according to  claim 1  further comprising a fresh water inlet in communication with a crude oil stream inlet.