Well Testing & EPF Equipments
Desalter or Electrostatic coalescers are used to coalescing of small water drops dispersed in the crude can be accomplishedby subjecting the water - in -oil emulsion to a high voltage electrical field. Desalter or Electro static coalescers separates a non-conductive liquid (oil) containing a dispersed conductive liquid (water) is subjected to an electrostatic field, the conductive particles or droplets are caused to combine by one of three physical phenomena are polarized droplets, droplets attracted to electrode due to an induced charge.
Droplet diameter is most important single parameter to control to aid in water settling since this term is squared in stokes law equation. Small increase in droplet size will create a much larger increase in settling velocity. In desalter or electrostatic coalescer it is necessary to predict droplet diameter, which must be separated from oil to meet a desired BS&W specification.
Field experience tends to indicate Desalter or Electrostatic treaters are effective at reducing water content in the crude to 0.2 to 0.5% level. Which helps to achieve desalter or electrostatic treater performance of 0.5 to 1.0% BS&W specification.