Removal Of Glycerin From Biodiesel Using An Electrostatic Process

Abstract

A vertical electrostatic coalescer comprises a first and second electrode surface and a horizontally disposed foraminous surface. The first electrode surface and horizontally disposed foraminous surface are at ground potential. The first and second electrode surfaces share the same planar orientation relative to the central longitudinal axis of the vessel. The unique arrangement of the vessel and opposing pairs of first and second electrode surfaces provides for a substantially uniform voltage field around a perimeter of the vessel and an effective voltage field for coalescence within a center of the vessel. A circular-shaped distributor pipe or a distributor housing serves to absorb momentum of the incoming emulsion stream and distribute the stream into an interior of the vessel.

What is claimed is: 
     
         1 . A method for promoting glycerin coalescence in a biodiesel stream comprising the steps of:
 passing the biodiesel stream into vertically elongated, closed vessel through a fluid inlet located at a lower portion of said vessel;   establishing a voltage field around a perimeter portion of said vessel and in a center portion of said vessel, said voltage field established by a set of grounded first electrodes located in an upper portion of said vessel and arranged as a horizontal planar grid lying perpendicular to a central vertical axis of said vessel and having supports which connect the grid to the vessel; and a first and a second set of charged second electrodes located in the upper portion of said vessel, the first and second sets arranged as horizontally oriented parallel rods lying perpendicular to the central vertical axis of said vessel, the first set lying entirely above and the second set lying entirely below the horizontal planar grid of grounded first electrodes;   coalescing glycerin in the biodiesel stream as the biodiesel stream flows upwardly through the voltage field, augmenting separation thereof from the biodiesel stream;   collecting the coalesced glycerin in a glycerin phase at a bottom of said vessel;   removing said glycerin phase from said vessel through a first fluid outlet located at a lower portion of said vessel; and   removing a remaining portion of the biodiesel stream from said vessel though a second fluid outlet located at a top portion of said vessel.   
     
     
         2 . A method according to  claim 1  wherein a horizontally disposed foraminous surface is located in a lower portion of said vessel and is in communication with an interior surface of said vessel to ground the foraminous surface. 
     
     
         3 . A method according to  claim 1  wherein one or more connector passageways are located on an interior surface of said horizontal planar grid and allow for one or more connectors connectable to said first and second sets of second electrodes to pass therethrough. 
     
     
         4 . A method according to  claim 1  wherein a voltage between each opposing pair of first and second electrodes is in a range of 2 kV/inch to 8 kV/inch. 
     
     
         5 . A method according to  claim 1  wherein a distributor housing is connected to said fluid inlet and has an array of ports located at an upper portion of said distributor housing. 
     
     
         6 . A method according to  claim 1  further comprising the step of regulating the level of the glycerin phase in said vessel with a level control located in a lower portion of said vessel.