EP0585054A1 - Electrostatic air filter - Google Patents
Electrostatic air filter Download PDFInfo
- Publication number
- EP0585054A1 EP0585054A1 EP93306564A EP93306564A EP0585054A1 EP 0585054 A1 EP0585054 A1 EP 0585054A1 EP 93306564 A EP93306564 A EP 93306564A EP 93306564 A EP93306564 A EP 93306564A EP 0585054 A1 EP0585054 A1 EP 0585054A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- filter
- inner screen
- frame
- outer screens
- screens
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
- B03C3/02—Plant or installations having external electricity supply
- B03C3/04—Plant or installations having external electricity supply dry type
- B03C3/14—Plant or installations having external electricity supply dry type characterised by the additional use of mechanical effects, e.g. gravity
- B03C3/155—Filtration
Definitions
- This invention relates to a filter for filtering air of the type which includes an electrically conductive inner screen, a pair of electrically conductive outer screens locatable parallel to the inner screen, and a dielectric filter medium disposed between the inner screen and each of the outer screens.
- the filter In use, the filter is connected to an electrical power source with the outer screens held at ground potential and the inner screen held at a potential difference relative to the ground screens in the range 5-10 kV.
- the resultant electrostatic field polarises the filter media which attracts to the media any particles such as dust or smoke which are suspended in the air caused to flow through the filter.
- the efficiency of the filter is increased by this polarisation. Once the filter media are fully contaminated with particles they can be replaced.
- FIG. 1 An example of a known electrostatic air filter is disclosed in US patent 4,886,526 published on the 12th December 1989 and is illustrated at Figure 1.
- the filter comprises a filter cartridge 2 containing a pair of fibre dielectric filters 4 between which is sandwiched an inner screen 6.
- the filter pads 4 and screen 6 are contained within a cardboard container 8 having holes in the top and bottom surfaces to allow air to enter and flow through the filter.
- the container 8 is placed in a wire mesh frame whose sides form outer ground screens (not shown).
- the inner screen 6 is connectable to a high tension voltage source via an external electrical connector 10.
- ground screens are parallel to the inner screen and kept at ground potential whereby the filter pads 4 are polarised as described above.
- an air filter for filtering air including an electrically conductive inner screen, a pair of electrically conductive outer screens locatable parallel to the inner screen and a dielectric filter medium disposed between the inner screen and each outer screens is characterised in that the inner screen is supported by a frame so as to channel all air passing through the filter through the inner screen.
- the frame is configured so as to channel the air passing through the filter through the inner screen, the air will tend to flow in the region where there is an electrostatic field of the desired level with a very much reduced possibility of the air leaking around the side of the screen through filter material which is operating at less than optimum efficiency.
- the filter of the present invention is arranged so that the regions of the inner screen and outer screens adjacent the fibre media are substantially co-extensive.
- This structure provides that the electric field between the inner screen and outer screens is substantially constant over the whole of the dielectric medium. This allows the electrical potential applied to the screens to be set at the most efficient level, which level will provide optimum efficiency, throughout the filter. This is in contrast to prior art electrostatic filters where field distortion at the ends of the filter reduces the efficiency of the filter in those regions.
- the frame may be provided with recesses into which the edges of the filter media are removably insertable to retain the filter media in position adjacent the inner screen.
- removable filter media may be used with the filter yet be retained in position during use. This allows the filter media to be replaced independently of the inner screen as they become contaminated as well as allowing access to the inner screen for cleaning thereby obviating the need to discard the inner screen once it becomes contaminated.
- a convenient arrangement for use with removable filter media is one in which the outer screens are each hinged to the frame so as to be movable between a first, closed position, parallel to the inner screen and a second, open position, to allow removal of one of the filter media. This allows each filter medium to be removed without scraping and possibly snagging the ground screens.
- the filter includes latches for releasably retaining the outer screens in the closed position and a releasable retaining means for holding the outer screens in the open position for removal of the filter media.
- the outer screens may be connected by an electrical conductor external to the frame to help ensure that they are at a common ground potential. This can be achieved, for example, by a metal band seated on the hinges of the ground screens in the embodiment where the ground screens are hinged for access to the filter media.
- the present invention is also applicable to arrangements in which the inner screen, outer screens, and filter media are all formed into a single, disposable unit if it is not desired to replace the filters or clean the inner screen but rather to provide a readily replaceable cartridge-type unit for insertion into an air filter installation.
- the filter media may include electrically conductive surfaces at least over the regions of the filter media in contact with the outer screen when in the closed position.
- the frame may be of an extruded plastics material and can be provided with means for connecting the inner and outer screens to the electrical supply.
- a filter in accordance with this invention comprising a plastics frame 20.
- the sides of the frame are E-shaped in section.
- An inner screen 22 of wire mesh is supported by central arms 24 of the plastics frame 20.
- a pair of outer screens 26, 28, also of wire mesh, are hinged to the opposite faces of the frame 20 by way of hinges 30. Latches 27 secure the outer screens 26 and 28 in the closed position.
- Filter media in the form of fibreglass filter pads 32, 34 fit between the respective outer wire mesh screens 26, 28 and the inner screen 22.
- the sides of the filter pads 26, 28 are coated with an electrically conductive coating 36.
- An electrical terminal 38 is connected to the inner wire mesh screen 22.
- the outer mesh screens 26, 28 are connected to earth via a filter installation (not shown) into which the filter is insertable and to each other by a metal band 40. In use, an HT potential difference is applied between the inner screen 22 and outer wire mesh screens 26 and 28.
- the filter operates in the same way as the prior art filter. However, because the thickness of the filter pads 21, 24 is uniform across the width of the screens producing the electric field, the operating potential of the filter can be optimised over the whole of the filter media 32, 34.
- the production costs of the filter can be reduced because the inner wire mesh screen 22 does not have to be fabricated as part of a filter media-inner screen unit.
- the cost of replacing the filter when it has become contaminated is reduced because only the two filter pads 32, 34 need to be replaced.
- the frame assembly can be removed from an installation so that the inner screen 22 can be washed.
- a locking arrangement 40 formed of like arms 42 and 44 pivotally joined to respective outer screens 26 and 28 at pivots 46 and 48 and to each other at the ends distant from the outer screens 26 and 28 at pivot 50 having a pivot pin 52 extending from the pivot 50 towards the frame 20.
- the locked arms hold the outer screens 26 and 28 apart in the open position to allow removal of the filter media 32 and 34 with reduced chance of snagging the outer screens 26 and 28 by positioning the pivot pin 52 between a pair of ledges 54 protruding from the frame 20. It will be appreciated other means can be readily devised to hold the hinged outer screens 26, 28 in their open position.
- the inner screen may be a sheet of polyester impregnated with carbon which can provide an electrically conductive screen whilst providing additional filtering particularly effective at reducing odours in the air flow.
- Such sheets are readily available from a number of manufacturers, and simple trial and error will determine which grade provides an acceptable porosity to the air filter in a given air filter design.
Abstract
An electrostatic air filter has an insulating plastics frame (20) supporting an inner wire mesh screen (22), a pair of disposable fibreglass filter pads (32, 34) and a pair of outer wire mesh screens (26, 28) hinged to frame (20). The frame (20) supports the inner screen (22) so as to channel all the air flow through the filter through the inner screen (22). Co-extensive outer screens provide a more even electric field over the fibre pads (32, 34). The filter consequently can operate at nearer optimum efficiency with reduced leakage of the air flow through regions of the fibre pads (32, 34) exposed to a sub-optimum electric field. The inner screen may comprise a sheet of polyester impregnated with carbon.
Description
- This invention relates to a filter for filtering air of the type which includes an electrically conductive inner screen, a pair of electrically conductive outer screens locatable parallel to the inner screen, and a dielectric filter medium disposed between the inner screen and each of the outer screens.
- In use, the filter is connected to an electrical power source with the outer screens held at ground potential and the inner screen held at a potential difference relative to the ground screens in the range 5-10 kV. The resultant electrostatic field polarises the filter media which attracts to the media any particles such as dust or smoke which are suspended in the air caused to flow through the filter. The efficiency of the filter is increased by this polarisation. Once the filter media are fully contaminated with particles they can be replaced.
- An example of a known electrostatic air filter is disclosed in US patent 4,886,526 published on the 12th December 1989 and is illustrated at Figure 1. The filter comprises a
filter cartridge 2 containing a pair of fibre dielectric filters 4 between which is sandwiched aninner screen 6. The filter pads 4 andscreen 6 are contained within a cardboard container 8 having holes in the top and bottom surfaces to allow air to enter and flow through the filter. The container 8 is placed in a wire mesh frame whose sides form outer ground screens (not shown). Theinner screen 6 is connectable to a high tension voltage source via an externalelectrical connector 10. - In use the ground screens are parallel to the inner screen and kept at ground potential whereby the filter pads 4 are polarised as described above.
- It is an object of the invention to provide an improved filter.
- According to the present invention an air filter for filtering air including an electrically conductive inner screen, a pair of electrically conductive outer screens locatable parallel to the inner screen and a dielectric filter medium disposed between the inner screen and each outer screens is characterised in that the inner screen is supported by a frame so as to channel all air passing through the filter through the inner screen.
- Because the frame is configured so as to channel the air passing through the filter through the inner screen, the air will tend to flow in the region where there is an electrostatic field of the desired level with a very much reduced possibility of the air leaking around the side of the screen through filter material which is operating at less than optimum efficiency.
- Preferably, the filter of the present invention is arranged so that the regions of the inner screen and outer screens adjacent the fibre media are substantially co-extensive. This structure provides that the electric field between the inner screen and outer screens is substantially constant over the whole of the dielectric medium. This allows the electrical potential applied to the screens to be set at the most efficient level, which level will provide optimum efficiency, throughout the filter. This is in contrast to prior art electrostatic filters where field distortion at the ends of the filter reduces the efficiency of the filter in those regions.
- The frame may be provided with recesses into which the edges of the filter media are removably insertable to retain the filter media in position adjacent the inner screen. With such an arrangement removable filter media may be used with the filter yet be retained in position during use. This allows the filter media to be replaced independently of the inner screen as they become contaminated as well as allowing access to the inner screen for cleaning thereby obviating the need to discard the inner screen once it becomes contaminated. A convenient arrangement for use with removable filter media is one in which the outer screens are each hinged to the frame so as to be movable between a first, closed position, parallel to the inner screen and a second, open position, to allow removal of one of the filter media. This allows each filter medium to be removed without scraping and possibly snagging the ground screens.
- In preferred arrangements the filter includes latches for releasably retaining the outer screens in the closed position and a releasable retaining means for holding the outer screens in the open position for removal of the filter media.
- The outer screens may be connected by an electrical conductor external to the frame to help ensure that they are at a common ground potential. This can be achieved, for example, by a metal band seated on the hinges of the ground screens in the embodiment where the ground screens are hinged for access to the filter media.
- It will be appreciated that the present invention is also applicable to arrangements in which the inner screen, outer screens, and filter media are all formed into a single, disposable unit if it is not desired to replace the filters or clean the inner screen but rather to provide a readily replaceable cartridge-type unit for insertion into an air filter installation.
- The filter media may include electrically conductive surfaces at least over the regions of the filter media in contact with the outer screen when in the closed position.
- The frame may be of an extruded plastics material and can be provided with means for connecting the inner and outer screens to the electrical supply.
- An embodiment of the present invention will now be described, by way of example only, and with reference to the accompanying drawings, of which:
- Figure 1 is a sectional view of a prior art air filter;
- Figure 2 is a sectional view of an air filter in accordance with the present invention; and
- Figures 3 and 4 are a side view and a plan view, respectively, of the air filter of Figure 2 showing means for holding the hinged outer screens in the open position.
- The prior art filter of Figure 1 has already been described.
- Referring now to Figures 2, 3 and 4 of the drawings, there is shown a filter in accordance with this invention comprising a
plastics frame 20. The sides of the frame are E-shaped in section. Aninner screen 22 of wire mesh is supported bycentral arms 24 of theplastics frame 20. A pair ofouter screens frame 20 by way ofhinges 30.Latches 27 secure theouter screens fibreglass filter pads wire mesh screens inner screen 22. The sides of thefilter pads conductive coating 36. - An
electrical terminal 38 is connected to the innerwire mesh screen 22. Theouter mesh screens metal band 40. In use, an HT potential difference is applied between theinner screen 22 and outerwire mesh screens - The filter operates in the same way as the prior art filter. However, because the thickness of the
filter pads 21, 24 is uniform across the width of the screens producing the electric field, the operating potential of the filter can be optimised over the whole of thefilter media - The production costs of the filter can be reduced because the inner
wire mesh screen 22 does not have to be fabricated as part of a filter media-inner screen unit. - The cost of replacing the filter when it has become contaminated is reduced because only the two
filter pads inner screen 22 can be washed. - Referring specifically to Figure 3, there is shown a
locking arrangement 40 formed oflike arms outer screens pivots outer screens pivot 50 having apivot pin 52 extending from thepivot 50 towards theframe 20. - The locked arms hold the
outer screens filter media outer screens pivot pin 52 between a pair ofledges 54 protruding from theframe 20. It will be appreciated other means can be readily devised to hold the hingedouter screens - The inner screen may be a sheet of polyester impregnated with carbon which can provide an electrically conductive screen whilst providing additional filtering particularly effective at reducing odours in the air flow. Such sheets are readily available from a number of manufacturers, and simple trial and error will determine which grade provides an acceptable porosity to the air filter in a given air filter design.
Claims (10)
- A filter for filtering air including an electrically conductive inner screen (20), a pair of electrically conductive outer screens (23, 28) locatable parallel to the inner screen (20) and a dielectric filter medium (21, 29) disposed between the inner screen (20) and each outer screens (23, 28) characterised in that:
the inner screen is supported by a frame (24) so as to channel all air passing through the filter through the inner screen. - A filter as claimed in claim 1 in which the regions of the inner screen (22) and outer screens (26, 28) adjacent the fibre media (32, 34) are substantially co-extensive.
- A filter as claimed in either one of claims 1 and 2 in which the frame (20) has recesses into which the edges of filter media (32, 34) are removably insertable to retain the filter media (32, 34) in position adjacent the inner screen (20).
- A filter as claimed in claim 3 in which the outer screens (26, 28) are each hinged to the frame (20) so as to be moveable between a first, closed position parallel to the inner screen (20) and a second, open position to allow removal of one of the filter media.
- A filter as claimed in claim 4 and including latch means (27) for releasably retaining the outer screens (26, 28) in the closed position.
- A filter as claimed in either one of claims 4 and 5 and including means for releasably retaining the outer screens in the open position.
- A filter as claimed in any preceding claim in which the outer screens (26, 28)are electrically connected together by an electrical conductor (40) external to the frame (20).
- A filter as claimed in any preceding claim in which this filter media (32, 34)include electrically conductive surfaces (36) at least over regions of the filter media (32, 34) in contact with the outer screens (26, 28)when in the closed position.
- An air filter as claimed in any preceding claim in which the inner screen comprises a sheet of polyester impregnated with carbon.
- An air filter installation including a filter as claimed in any preceding claim and in which the filter is removable from the installation.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB929217666A GB9217666D0 (en) | 1992-08-20 | 1992-08-20 | Air filter |
GB9217666 | 1992-08-20 |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0585054A1 true EP0585054A1 (en) | 1994-03-02 |
Family
ID=10720634
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP93306564A Withdrawn EP0585054A1 (en) | 1992-08-20 | 1993-08-19 | Electrostatic air filter |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP0585054A1 (en) |
GB (1) | GB9217666D0 (en) |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1998020978A1 (en) * | 1996-11-08 | 1998-05-22 | Joannou Constantinos J | Ionizing and polarizing electronic air filter |
CN103041665A (en) * | 2013-01-08 | 2013-04-17 | 戴若夫 | High-efficiency and low-resistance electrostatic dust collection filter box |
US8814994B2 (en) | 2005-12-29 | 2014-08-26 | Environmental Management Confederation, Inc. | Active field polarized media air cleaner |
CN102500166B (en) * | 2005-12-29 | 2015-08-19 | 环境管理联合公司 | The active field polarized media air cleaner improved |
CN106091109A (en) * | 2016-06-05 | 2016-11-09 | 镇江市亿鑫电气设备有限责任公司 | Plasma air purifier defecator |
US9764331B2 (en) | 2005-12-29 | 2017-09-19 | Environmental Management Confederation, Inc. | Filter media for active field polarized media air cleaner |
US9789494B2 (en) | 2005-12-29 | 2017-10-17 | Environmental Management Confederation, Inc. | Active field polarized media air cleaner |
US11452960B2 (en) | 2015-04-14 | 2022-09-27 | Environmental Management Confederation, Inc. | Corrugated filtration media for polarizing air cleaner |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2124215A1 (en) * | 1971-02-09 | 1972-09-22 | Soltis Charles | |
EP0229857A1 (en) * | 1985-11-04 | 1987-07-29 | Engineering Dynamics Limited | Electrostatic air filter |
WO1991008368A2 (en) * | 1989-11-28 | 1991-06-13 | Pick William E | A construction for supporting a flexible sheet |
US5108470A (en) * | 1988-11-01 | 1992-04-28 | William Pick | Charging element having odor and gas absorbing properties for an electrostatic air filter |
-
1992
- 1992-08-20 GB GB929217666A patent/GB9217666D0/en active Pending
-
1993
- 1993-08-19 EP EP93306564A patent/EP0585054A1/en not_active Withdrawn
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2124215A1 (en) * | 1971-02-09 | 1972-09-22 | Soltis Charles | |
EP0229857A1 (en) * | 1985-11-04 | 1987-07-29 | Engineering Dynamics Limited | Electrostatic air filter |
US5108470A (en) * | 1988-11-01 | 1992-04-28 | William Pick | Charging element having odor and gas absorbing properties for an electrostatic air filter |
WO1991008368A2 (en) * | 1989-11-28 | 1991-06-13 | Pick William E | A construction for supporting a flexible sheet |
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1998020978A1 (en) * | 1996-11-08 | 1998-05-22 | Joannou Constantinos J | Ionizing and polarizing electronic air filter |
US8814994B2 (en) | 2005-12-29 | 2014-08-26 | Environmental Management Confederation, Inc. | Active field polarized media air cleaner |
CN102500166B (en) * | 2005-12-29 | 2015-08-19 | 环境管理联合公司 | The active field polarized media air cleaner improved |
US9764331B2 (en) | 2005-12-29 | 2017-09-19 | Environmental Management Confederation, Inc. | Filter media for active field polarized media air cleaner |
US9789494B2 (en) | 2005-12-29 | 2017-10-17 | Environmental Management Confederation, Inc. | Active field polarized media air cleaner |
US11007537B2 (en) | 2005-12-29 | 2021-05-18 | Environmental Management Confederation, Inc. | Filter media for active field polarized media air cleaner |
CN103041665A (en) * | 2013-01-08 | 2013-04-17 | 戴若夫 | High-efficiency and low-resistance electrostatic dust collection filter box |
CN103041665B (en) * | 2013-01-08 | 2015-11-18 | 戴若夫 | Efficient low-resistance electrostatic dust removal filter case |
US11452960B2 (en) | 2015-04-14 | 2022-09-27 | Environmental Management Confederation, Inc. | Corrugated filtration media for polarizing air cleaner |
CN106091109A (en) * | 2016-06-05 | 2016-11-09 | 镇江市亿鑫电气设备有限责任公司 | Plasma air purifier defecator |
Also Published As
Publication number | Publication date |
---|---|
GB9217666D0 (en) | 1992-09-30 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
CA1314237C (en) | Charging element having odour absorbing properties for an electrostatic air filter | |
EP0337017B1 (en) | Cartridge type electrostatic air filter | |
CA1291520C (en) | Electronic air filtration system | |
US5330559A (en) | Method and apparatus for electrostatically cleaning particulates from air | |
EP0585054A1 (en) | Electrostatic air filter | |
US2908348A (en) | Electrostatic air filter | |
US4623365A (en) | Recirculating electric air filter | |
US5474599A (en) | Apparatus for electrostatically cleaning particulates from air | |
KR100355370B1 (en) | filter | |
CA2167054C (en) | Electrofilter | |
JPH05502278A (en) | Flexible seat support structure | |
CA2520848C (en) | Self ionizing pleated air filter system | |
MXPA02006171A (en) | Structures for electrostatic vbank air filters. | |
AU2006330440B2 (en) | Conductive bead for active field polarized media air cleaner | |
EP0512680B1 (en) | One-way guided filter pad assembly | |
CA2092256A1 (en) | Finite particle removal system | |
WO1987001301A1 (en) | Conductive filter cartridge and method for making same | |
EP0229857A1 (en) | Electrostatic air filter | |
CA2270976C (en) | Ionizing and polarizing electronic air filter | |
US11369976B2 (en) | Electrostatic filter corner latch | |
US4349511A (en) | Air purification apparatus | |
US20040093756A1 (en) | Filter device for a hair dryer | |
KR100270856B1 (en) | Filter system for removal of particle from hydrocarbon fluids | |
EP0033807A2 (en) | Electrode assembly | |
JPH0332712A (en) | Filter for air cleaner |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AT BE CH DE ES FR GB IE IT LI LU MC NL PT |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
18D | Application deemed to be withdrawn |
Effective date: 19940903 |