Electrostatic separator

• US 4,588,423 A
• Filed: 07/25/1984
• Issued: 05/13/1986
• Est. Priority Date: 06/30/1982
• Status: Expired due to Term

• Current Assignee: Donaldson Company Incorporated
• Original Assignee: Donaldson Company Incorporated
• Inventors: Gillingham, Gary R., Rothman, James C.
• Primary Examiner(s): LACEY, DAVID LYNN
• Application Number:
  US06/634,652
• Time in Patent Office: 657 Days
• Field of Search: 55/117, 55/118, 55/120, 55/127, 55/135-138, 55/145, 55/146, 55/148, 55/150, 55/152, 55/154, 55/301, 55/348, 55/391, 55/396, 55/431, 55/435
• US Class Current: 96/43
• CPC Class Codes: B03C 3/011 Prefiltering; Flow controlling
• CPC Class Codes: B03C 3/12 characterised by separation of ionising and collecting stations
• CPC Class Codes: B03C 3/15 Centrifugal forces
• CPC Class Codes: B03C 3/80 by gas or solid particle blasting
• CPC Class Codes: F01N 2590/08 for heavy duty applications, e.g. trucks, buses, tractors, locomotives
• CPC Class Codes: F01N 3/01 by means of electric or electrostatic separators
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

An apparatus (10) for cleaning a flow of particulate-laden gas is disclosed. The apparatus (10) has a housing (11) having a gas inlet (15) and a gas outlet (16) to permit a flow of gas through the housing (11). Suspended inside the housing (11) is an electrode element (20) having a charging element (26) which defines with the housing (11) a charging chamber (31) adjacent the gas inlet (15) and having an electrostatic force element (25) which defines with the housing (11) a collecting chamber (32) adjacent the gas outlet (16). The electrode element (20) is maintained at a voltage differential from the housing (11) for charging particulate in the charging chamber (31) and subjecting charged particulate in the collecting chamber (32) to an electrostatic force, whereby charged particulate is forced outwardly toward the housing (11) and removed from the gas flow. In yet another embodiment, a helical vane structure (33) is mounted in the housing (11) at the gas inlet (15), whereby the particulate in gas is subjected to a centrifugal force and forced outwardly towards the housing (11), the centrifugal force cooperating with the electrostatic force to enable efficient removal of particulate from a flow of particulate-laden gas.

Claims

1. An apparatus for cleaning a flow of particulate-laden gas, comprising:

(a) a housing having a gas inlet for receiving particulate-laden gas and a gas outlet for discharging clean gas, said housing having an inner wall forming a passageway axially extending from said gas inlet to said gas outlet to permit a flow of gas therethrough;

(b) electrode means suspended axially in said passageway of said housing, said electrode means having a charging element adjacent to said gas inlet for charging particulate in said particulate-laden gas, said charging element defining with said inner wall of said housing a charging chamber in said housing, said electrode means further having an electrostatic force element adjacent to said gas outlet for subjecting said charged particulate to an electrostatic force, said electrostatic force element defining with said inner wall of said housing a collecting chamber in said housing, said inner wall of said housing being porous proximate said collecting chamber, said housing further including a nonporous outer wall spaced from said inner wall, said inner wall and said outer wall cooperating to form an enclosed cavity surrounding said collecting chamber, said electrostatic force element being constructed and arranged to inhibit formation of a corona when said electrode means and said housing are maintained at a voltage differential sufficient to cause a corona discharge from said charging element;

(c) voltage means electrically connected to said electrode means of said housing at a voltage differential sufficient to cause a corona discharge at said charging element for charging particulate located in said charging chamber and sufficient to subject particulate located in said collecting chamber to an electrostatic force, whereby the particulate is forced outwardly towards said housing, said voltage means including an electrical wire extending from a power supply externally located of said passageway to said electrode means;

(d) support means for supporting said electrode means in said housing, said support means including a dielectric member extending into said passageway of the housing, said electrical wire traveling within said dielectric member to said electrode means, said dielectric member extending through an aperture of larger diameter than said dielectric member in said inner wall so as to be separated from said inner wall by an air space surrounding said dielectric member at its intersection with said inner wall, said electrode means being secured to said dielectric member, said dielectric member being interconnected to said housing at a location along said dielectric member outside of said passageway;

(e) vortex means within said passageway of said housing intermediate of said collecting chamber and said gas inlet for imparting a rotating motion to the gas flow, whereby particulate is forced outwardly toward said inner wall;

(f) scavenge means within said passageway of said housing for separating particulate and agglomerated masses of particulate from the gas flow, said scavenge means comprising a generally frustoconical structure located in said collecting chamber proximate the end of said collecting chamber facing said gas outlet, said frustoconical structure having a base portion attached to said housing and further having an apex portion axially directed towards the gas inlet, said frustoconical structure further having an opening in said apex for allowing a flow of gas generally through the center of said frustoconical structure, said scavenge means further including an outlet extending from said passageway in said housing proximate said base portion of said frustoconical structure to the outside of said housing, said scavenge means outlet providing a secondary gas flow out of said housing from said passageway, said scavenge means outlet being positioned on the side of said base portion facing said gas inlet, said secondary gas flow including said separated particulate and agglomerated masses of particulate; and

(g) particulate removing means for removing particulate collected on the inside of said porous inner wall of said housing, said particulate removing means including means in communication with said enclosed cavity for introducing pressurized gas into said enclosed cavity surrounding said collecting chamber, whereby a radially inwardly flow of gas through said porous inner wall of said housing is caused thereby dislodging particulate and agglomerated masses of particulate from the inside of said porous inner wall of said housing.

2. An apparatus for cleaning a flow of particulate-laden gas in accordance with claim 1, wherein said inner wall of said housing includes a plurality of louvered inlets so as to form said vortex means and the gas inlet.

3. An apparatus for cleaning a flow of particular-laden gas in accordance with claim 1, wherein said vortex means comprises a helical vane-like structure positioned in said housing between said gas inlet and said electrostatic force element.

4. An apparatus in accordance with claim 1, including a secondary filtration apparatus in flow communication with said scavenge means outlet for further filtration of the particulate in said secondary gas flow.

5. An apparatus in accordance with claim 1, wherein said dielectric support member extends through said enclosed cavity, whereby pressurized gas is forced through said air space surrounding said dielectric member at its intersection with said inner wall thereby preventing the buildup of particulate on said dielectric support member.

6. An apparatus in accordance with claim 1, wherein said dielectric support member extends through a second enclosed cavity surrounding said housing and is fixedly attached to an outer wall of said second enclosed cavity, the second enclosed cavity being in communication with the particulate removing means;

said dielectric member passing through an aperture in said inner wall of said housing which is of larger diameter than said dielectric support member so as to define a space through which pressurized gas introduced into said second enclosed cavity is forced into said housing, thereby preventing the buildup of particulate on said dielectric support member.

7. An apparatus for cleaning a flow of particulate-laden gas, comprising:

(a) a housing having a gas inlet for receiving particulate-laden gas and a gas outlet for discharging clean gas in communication with each other to permit a flow of gas therethrough;

(b) a plurality of tubular members contained in said housing, each of said tubular members having a gas inlet and gas outlet, said tubular members each having an inner wall forming a passageway axially extending from said gas inlet thereof to said gas outlet thereof to permit a flow of gas therethrough, the gas inlet of said tubular members facing said gas inlet of said housing;

(c) first baffle means positioned within said housing and extending tranversely of said housing with openings therein to accommodate said tubular members and supporting said tubular members in said housing;

(d) an electrode element suspended axially in each passageway of said tubular members, said electrode element having a charging element adjacent to said gas inlet of said tubular member, said charging element defining with said inner wall of said tubular member a charging chamber, said electrode element further having an electrostatic force element adjacent to said gas outlet of said tubular member, said electrostatic force element defining with said inner wall of said tubular member a collecting chamber;

(e) means for supporting said electrode elements in said tubular members;

(f) vortex generating means mounted adjacent said gas inlets in said passageways of each of said tubular members for causing a rotating gas flow, whereby the particulate in said gas is subjected to a centrifugal force and thrown radially outwardly toward said inner walls of said tubular members;

(g) voltage means for maintaining said electrode elements and said tubular members at a voltage differential sufficient to cause corona discharge at said charging element for charging particulate located in said charging chamber and sufficient to subject particulate located in said collecting chamber to an electrostatic force, whereby the charged particulate is forced outwardly towards said inner walls of said tubular members, said voltage means including an electrical wire extending from a power supply into said housing;

(h) scavenge means within said housing for separating said particulate from the gas flow, said scavenge means including a frustoconical structure positioned at least partially within said passageway proximate the gas outlet end of each of said tubular members, each of said frustoconical structures having a base portion and an apex portion coaxially directed toward said gas inlet of its respective tubular member, said apex portion having an opening to permit the flow of gas therethrough, said scavenge means further including an outlet extending from said passageway of each of said tubular members proximate said base portion of said frustoconical structure to the outside of said housing, said scavenge means outlet being on the side of said base portion facing said gas inlet and providing a secondary flow of gas out of said housing; and

(i) said support means comprising an electrically conductive grid structure attached to said electrode elements so as to maintain said electrode elements at operating voltage, said grid structure including dielectric support members extending through apertures in an inner wall of said housing enclosing said tubular members so as to provide an air space surrounding said support members at the boundary of said inner wall of said housing, said electrical wire traveling within one of said dielectric support members to said electrically conductive grid.

8. A particle separator apparatus for cleaning a flow of particulate-laden gas, comprising:

(a) a housing having first and second ends, said housing having a gas inlet for receiving particulate-laden gas at said first end and a gas outlet for discharging clean gas at said second end, said housing having an inner wall forming a passageway axially extending from said gas inlet to said gas outlet to permit a flow of gas therethrough;

(b) charging means suspended in said passageway of said housing for charging particulate in the particulate-laden gas flow, said charging means providing a corona discharge upon the application of a predetermined voltage, said charging means being positioned in said housing so as to define with said inner wall of said housing a charging chamber wherein the particulate is provided with an electrical charge;

(c) electrostatic force means suspended in said passageway of said housing at a location between said electrostatic charging means and said gas outlet, said electrostatic force means providing an electrostatic force upon application of a predetermined voltage for forcing said charged particulate in said particulate-laden gas outwardly towards said housing, said electrostatic force means defining with said inner wall of said housing a collecting chamber wherein said particulate is collected proximate the periphery of said collecting chamber, said inner wall of said housing being porous proximate said collecting chamber, said housing further including a nonporous outer wall spaced from said inner wall, said inner wall and said outer wall cooperating to form an enclosed cavity surrounding said collecting chamber;

(d) power means electrically interconnected to said charging means and said electrostatic force means for providing said predetermined voltage;

(e) vortex generating means mounted in said passageway of said housing between said gas inlet and said electrostatic force means for imparting a rotating flow to said particulate-laden gas flow, whereby particulate is subjected to a centrifugal force and thrown radially outwardly towards said inner wall of said housing;

(f) means in communication with said enclosed cavity for introducing a surge of gas under pressure into said enclosed cavity defined between said inner porous wall of said housing substantially surrounding said collecting chamber and said nonporous outer wall of said housing surrounding and separated from said porous wall of said housing, whereby a generally radially inwardly flow of pressurized gas through said inner porous wall of said housing into said collecting chamber is caused thereby disloding particulate and agglomerated masses of particulate which might have become attached on said inner porous wall; and

(g) scavenge means positioned within said passageway of said housing proximate the end of said collecting chamber facing said gas outlet for separating said particulate and agglomerated masses of particulate proximate the perihpery of said housing from the gas flow, said scavenge means comprising a generally frustoconical structure located on the inside of said passageway of said housing in said collecting chamber, said frustoconical structure having a base attached to said housing and having an apex axially directed toward said gas inlet, said frustoconical structure further having an opening at said apex for allowing the flow of gas generally through the center of said frustoconical structure, said scavenge means further comprising an outlet extending from said passageway in said housing to the outside of said housing for removal of said particulate and agglomerated masses of particulate from said housing as a secondary gas flow, said scavenge means outlet being located adjacent to said base of said frustoconical structure on the side of said base facing said gas inlet.

9. A particle separator apparatus in accordance with claim 8 wherein said vortex generating means comprises a helical vane structure mounted in said housing proximate said gas inlet.

10. An apparatus for cleaning a flow of particulate-laden gas in accordance with claim 8, wherein said inner wall of said housing has a generally tubular shape and wherein said vortex generating means includes a tangential inlet in said inner wall of said housing for causing a rotating gas flow.

11. An apparatus in accordance with claim 8, wherein said charging means includes a plurality of wires and plate-like members positioned in said housing between said vortex generating means and the gas inlet.

12. An apparatus for cleaning a flow of particulate-laden gas in accordance with claim 8, wherein said vortex generating means and the gas inlet include a plurality of louvered inlets in said inner wall of said housing.

13. An apparatus for cleaning a flow of particulate-laden gas, comprising:

(a) a housing having a gas inlet for receiving particulate-laden gas and a gas outlet for discharging clean gas, said gas inlet and said gas outlet being in communication so as to permit a flow of gas therethrough;

(b) a plurality of tubular members contained in said housing and generally aligned longitudinally therewith, each of said tubular members having a gas inlet and a gas outlet, said tubular members each having an inner wall forming a passageway axially extending from said gas inlet to said outlet to permit a flow of gas therethrough;

(c) first baffle means positioned within and extending transversely of said housing with openings therein to accomodate said tubular members and supporting said tubular members in said housing;

(d) charging means suspended in each of said passageways of said tubular members for charging particulate in said particulate-laden gas flow, said charging means providing a corona discharge upon the application of a predetermined voltage, said charging means being positioned in said tubular members so as to define with said inner wall of each of said tubular members a charging chamber wherein the particulate is provided with an electrical charge;

(e) electrostatic force means suspended in each of said passageways of said tubular members at a location between said electrostatic charging means and said gas outlet, said electrostatic force means providing an electrostatic force upon application of a predetermined voltage for forcing said charged particulate in said particulate-laden gas outwardly towards said inner wall of each of said tubular members, said electrostatic force means defining with said inner wall of each of said tubular members a collecting chamber wherein said particulate is generally collected proximate the periphery of said collecting chamber, said inner wall of said tubular members being porous proximate said collecting chamber, said inner wall of said tubular members cooperating with a nonporous inner wall of said housing spaced from said inner walls of said tubular members to form an enclosed cavity surrounding said collecting chambers of said tubular members;

(f) power means electrically interconnected to said charging means and said electrostatic force means for providing said predetermined voltage;

(g) vortex generating means mounted in said passageway adjacent said gas inlet of each of said tubular members for causing a rotating gas flow, whereby the particulate in said gas is subjected to centrifugal force and thrown radially outwardly toward said inner wall of each of said tubular members;

(h) means for introducing a surge of gas under pressure into said enclosed cavity whereby a flow of gas through said porour inner walls and into said collecting chambers is caused by the introduction of gas under pressure into said cavity, thereby dislodging particulate and agglomerated masses of particulate which might have become attached to said inner walls of said tubular members; and

(i) scavenge means positioned within said housing for separating said particulate and agglomerated masses of particulate from the gas flow so as to form a secondary gas flow, said scavenge means comprising a generally frustoconical structure located proximate the gas outlet of each of said tubular members, said frustoconical structure having a base portion interconnected to said housing and having an apex axially directed into said passageway of each of said tubular members toward the gas inlet of each of said tubular members, said frustoconical structures further having an opening at said apex for allowing the flow of gas generally through the center of said frustoconical structures, said scavenge means further including an outlet extending from said passageway of each of said tubular members to the outside of said housing for removal of said agglomerated masses of particulate from said housing in said secondary gas flow, said scavenge means outlet being located proximate the base portion of said frustoconical structure on the side of the base portion facing said gas inlet of each of said tubular members.