Electrostatically enhanced separator (EES)

• US 5,591,253 A
• Filed: 03/07/1995
• Issued: 01/07/1997
• Est. Priority Date: 03/07/1995
• Status: Expired due to Term

• Current Assignee: Electrical Power Research Institute
• Original Assignee: Electric Power Research Institute Incorporated
• Inventors: Smolensky, Leo A., Easom, Bruce H., Wysk, S. Ronald, Altman, Ralph F.
• Primary Examiner(s): Chiesa, Richard L.
• Application Number:
  US08/399,732
• Time in Patent Office: 672 Days
• Field of Search: 96/61, 96/55, 96/57, 95/78, 95/63, 95/69, 95/70, 55/454, 55/460, 55/459.1
• US Class Current: 96/61
• CPC Class Codes: B01D 45/16 generated by the winding course of the gas stream , the centrifugal forces being generated solely or partly by mechanical means, e.g. fixed swirl vanes
• CPC Class Codes: B03C 3/15 Centrifugal forces
• CPC Class Codes: B04C 11/00 Accessories, e.g. safety or control devices, not otherwise provided for , e.g. regulators, valves in inlet or overflow ductingwith electrostatic precipitating arrangements B03C3/14
• CPC Class Codes: B04C 2009/001 with means for electrostatic separation
• CPC Class Codes: B04C 3/06 Construction of inlets or outlets to the vortex chamber
• CPC Class Codes: B04C 5/04 Tangential inlets
• CPC Class Codes: B04C 5/14 Construction of the underflow ducting; Apex constructions; Discharge arrangements ; discharge through sidewall provided with a few slits or perforations provided with a great number of slits or perforations B04C5/10
• CPC Class Codes: B07B 7/086 generated by the winding course of the gas stream

Abstract

An electrostatically enhanced separator (EES) provides mechanical and electrostatic separation of particles from gas stream to yield a compact and highly efficient separation system. The EES (10) may be incorporated in a collection system as well using a conventional collection device such as a cyclone collector (32), bag filter (37) or electrostatic precipitator (38). The EES (10) includes a cylindrical-walled separation chamber (12) with an inlet passage (13), a clean flow outlet (21), and a particle outlet passage (15). The inlet passage (13) and particle outlet passage (15) are both thin elongated slits which open tangentially to the cylindrical wall of the chamber for providing a substantially flush incoming flow path dispersed lengthwise along the wall.

Claims

1. An apparatus for separating particles from a gas stream comprising:

a separation vessel including a cylindrical-walled separation chamber bound at opposing ends, an inlet passage for admitting a particulate laden gas stream into said separation chamber and a particle outlet passage for expelling a concentrated stream of particles disentrained from said gas stream, said inlet passage and particle outlet passage both further comprising a thin elongated slit opening tangentially to cylindrical walls of said separation chamber and providing a substantially flush incoming flow path dispersed lengthwise along said wall;

two vortex finders suspended centrally within the separation vessel between the ends thereof and establishing an end-to-end outgoing clean flow path through the separation vessel and out from the ends thereof;

an elongated discharge electrode suspended centrally within the separation vessel between the ends thereof; and

a power supply connected between the cylindrical walls of the separation chamber of the separation vessel and the discharge electrode for establishing an electric potential therebetween which serves to charge the particles entrained in said incoming gas stream and repel charged particles in said separation vessel toward the wall of said separation chamber,

wherein a gas stream flowing into said inlet passage, through said separation chamber, and out from said particle outlet passage creates a vortex in said separation chamber which imparts a centrifugal force on the entrained particles toward the wall of said separation chamber, and said centrifugal force is augmented by said electrostatic force to propel said particles away from the entrance of the vortex finders and out through said outlet passage.

2. The apparatus for separating particles from a gas stream according to claim 1, wherein said discharge electrode comprises a cylindrical arrangement of louvers.

3. The apparatus for separating particles from a gas stream according to claim 2, wherein said louvers are involute about a central axis.

4. The apparatus for separating particles from a gas stream according to claim 2, wherein said louvers are directed outward from said central axis and are curved in a direction opposite to said vortex.

5. The apparatus for separating particles from a gas stream according to claim 2, wherein said louvers are connected to said power supply for electrostatically preventing said particles from permeating therethrough into said clean flow passage.

6. The apparatus for separating particles from a gas stream according to claim 1, wherein said inlet passage and outlet passage are directed along two parallel planes.

7. An apparatus for separating particles from a gas stream comprising a walled separation vessel having a length and respective ends and further having a substantially cylindrical separation chamber formed therein, respective spaced-apart inlet and outlet passage means formed in the separation vessel along the length thereof and communicating with the separation chamber therein, the inlet and outlet passage means being shaped as narrow slits extending said length of the separation vessel, such that a particulate-laden gas stream is received through the inlet passage means into the separation chamber tangentially to the walls thereof, and such that a particulate-concentrated gas stream is expelled from the separation chamber tangentially to the wall therof through the outlet passage means, a permeable core separator mounted within the separation vessel substantially concentrically of the separation chamber therein, means for directing a clean gas stream axially through the separation vessel and through the permeable core separator therein from one end of the separation vessel and through the other end thereof, thereby creating a vortex in the separation chamber which imparts a centrifugal force on the particles towards the wall of the separation vessel, means for pre-charging the particles in the particulate-laden gas stream upstream of the outlet passage means and at a given polarity, and means for establishing an electrostatic field between the permeable core separator and the walls of the separation vessel at the same polarity as the charge imparted on the particles, thereby repelling the particles from entering into the permeable core separator and propelling the particles towards the wall of the separation vessel, and thereby augmenting the centrifugal force to propel particles against the wall and outwardly through the outlet passage means.

8. An apparatus for separating particles from a gas stream, comprising:

a walled separation vessel having a length and opposite ends and further having a substantiality cylindrical separation chamber formed therein;

respective spaced-apart inlet and outlet passages formed in the separation vessel as narrow slits extending along the full length thereof and communicating with the separation chamber therein, such that a particulate laden gas stream is received through the inlet passage into the separation chamber tangentially to the walls of the separation vessel, such that a particulate concentrated gas stream is expelled from the separation chamber through the outlet passage tangentially to the walls of the separation vessel, and such that said particulate laden gas stream and said particulate concentrated gas stream create a vortex in the separation chamber which imparts a centrifugal force on the particles towards the walls of the separation vessel;

vortex finders longitudinally mounted within the separation vessel and defining an outgoing clean air path through said opposite ends thereof, wherein an inlet gap for the clean air from the separation chamber into said outgoing clean air path is maintained between said vortex finders;

a discharge electrode mounted within the separation vessel for imparting a charge of a certain polarity on the particles within the separation chamber; and

a power supply establishing an electrostatic field between the discharge electrode and the walls of the separation vessel, such that the established electrostatic field repels the charged particles towards the walls of the separation vessel, thereby preventing entrance of the charged particles into the outgoing clean air path.