A Demulsifier performs several functions. It can perform the functions of a free water
knockout, an electrostatic treater, a coalescer, a desalter, and a heater treater.
Produced gas is taken out of the liquid and discharged at the top of the vessel.
The vessel is divided into two sections. In the first section the free water can
be knocked out using coalescer plates. A Coalescer is a device that allows the
discontinuous phase of a liquid to attach itself and thus be separated out.
If there is very little free water and a tight emulsion the coalescer plates on the
entrance to the vessel can be replaced with heater tubes to heat the liquid.
In the inner section of the vessel there is an electrostatic probe that charges
the liquid, which causes the water to separate itself from the oil more rapidly, and
since in this section the liquid is moving downward, the water drops out more easily.
A water wash can be added to this section to reduce the salt concentration.
In the discharge section coalescer plates are used to continue to remove any water
left in the oil. It is less expensive than grids on the electrostatic section. Each
application requires customized design.