CA1046950A - Apparatus for removing particles from a gas stream - Google Patents
Apparatus for removing particles from a gas streamInfo
- Publication number
- CA1046950A CA1046950A CA226,841A CA226841A CA1046950A CA 1046950 A CA1046950 A CA 1046950A CA 226841 A CA226841 A CA 226841A CA 1046950 A CA1046950 A CA 1046950A
- Authority
- CA
- Canada
- Prior art keywords
- electrodes
- gas stream
- fibres
- coating
- asbestos
- 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.)
- Expired
Links
- 239000002245 particle Substances 0.000 title claims abstract description 9
- 239000011248 coating agent Substances 0.000 claims abstract description 23
- 238000000576 coating method Methods 0.000 claims abstract description 23
- 239000010425 asbestos Substances 0.000 claims abstract description 7
- 229910052895 riebeckite Inorganic materials 0.000 claims abstract description 7
- 230000005684 electric field Effects 0.000 claims abstract description 6
- 239000002657 fibrous material Substances 0.000 claims abstract description 5
- 239000004744 fabric Substances 0.000 claims description 4
- 229920000914 Metallic fiber Polymers 0.000 claims description 3
- 239000004753 textile Substances 0.000 claims description 3
- 239000011521 glass Substances 0.000 claims description 2
- 238000004513 sizing Methods 0.000 claims description 2
- 229910001220 stainless steel Inorganic materials 0.000 claims description 2
- 239000010935 stainless steel Substances 0.000 claims description 2
- 239000000126 substance Substances 0.000 claims description 2
- 229920002994 synthetic fiber Polymers 0.000 claims description 2
- 238000001771 vacuum deposition Methods 0.000 claims description 2
- 239000007788 liquid Substances 0.000 abstract description 2
- 239000007787 solid Substances 0.000 abstract description 2
- 239000007789 gas Substances 0.000 description 13
- 230000000694 effects Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 239000000428 dust Substances 0.000 description 4
- 238000000926 separation method Methods 0.000 description 3
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000011111 cardboard Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 239000011087 paperboard Substances 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
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
- B03C3/06—Plant or installations having external electricity supply dry type characterised by presence of stationary tube electrodes
-
- 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
- B03C3/34—Constructional details or accessories or operation thereof
- B03C3/40—Electrode constructions
- B03C3/60—Use of special materials other than liquids
Landscapes
- Electrostatic Separation (AREA)
- Water Treatment By Electricity Or Magnetism (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A dipole separator, wherein solid or liquid particles are removed from a gas stream by an electric field generated between two electrodes and having a relatively low intensity so that no ionisation occurs in the gas stream. In order to increase the separating efficiency, at least one of the elec-trodes is provided with a coating consisting of a fibrous mat-erial with a limited electric conductivity having a large number of outwardly projecting fibres, such as asbestos.
A dipole separator, wherein solid or liquid particles are removed from a gas stream by an electric field generated between two electrodes and having a relatively low intensity so that no ionisation occurs in the gas stream. In order to increase the separating efficiency, at least one of the elec-trodes is provided with a coating consisting of a fibrous mat-erial with a limited electric conductivity having a large number of outwardly projecting fibres, such as asbestos.
Description
The present invention rela~es to an apparatus for removing solid or llquid particles Erom a gas stream, wherein the gas stream flows through a separating space bounded by two -electrodes arrar,ged opposite to each other, and wherein an electric field is generated between the electrodes with such an intensity that substantially no ionisation occurs in the gas stream.
~ An apparatus of this kind is indicated, in practice, .~ as a dipole separator. Due to the use of a relatively low field intensity in the separating space, there is no, or substantially no ionisation in the gas stream, so that the separation is mainly based on the phenomenon that dipole charges are generated in -the particles to be removed. In order to a-ttain this effect, the field intensity in the separating space must be lower than a .1 critical value which may amount to 10-20 kV/cm when the gas stream is an air stream. The theory of dipole separation has been explained in an article by Dr. Gunter Zebel, entitled:
"Ueber die Aggregatbildung zwischen kugelformigen Aerosolteilchen ,,"~ .
mit parallel ausgerichteten Dipolmomenten" in the German ; 20 periodical "Staub", Vol. 23, Nr. 5, May 1963, pages 263-268.
A suitable construction for a dipole separator is disclosed in ~ .
U.S. Patent application No. ~47,775 which has subsequently issued July 20, 1976 to Van Dieperbrock as U.S. Patent No~
3,970,437.
West German Patent Application 594,681 ln-~e name of Prof. Dr.-Ing. Paul Denzel, published on April 29, 1971, discloses an apparatus for removing sulfur dioxide fro~ smoke gases by means of an electric field generated between two electrodes, wherein the electrodes are provided with metallic points. West-German 30 Patent Application 2,000,768 in the name of Karl Simon, published on July 2, 1971, discloses an apparatus for separating kitchen odours from an air stream, by means of an electric field . ~ .
' ~ , , ., . ' : - ' ~
.
41~9~
generated between two electrodes, wherein one of the electrodes is made of a hygroscopic material, such as paper or cardboard, impregnated with a conductive liquid.
Conventional dipole separators have the disadvantage that the separating efficiency is rather low.
The invention improves the efficiency of a dipole , separator in such a sense that a larger percentage of the particles suspended in the gas stream is removed.
According to the present invention there is provided apparatus for removing particles from a gas stream, comprising two oppositely arranged electrodes defining a separating space between them, means for leading the gas stream through said separatiny space, means for generating an electric field between ~ the said electrodes having a relatively low intensity so that `~1 substantially no ionisation occurs in the gas stream, and a -`j coating on at least one of the said electrodes, consisting ofa fibrous material with a limited electric conductivity, having a large number of outwardly projecting thin fibres.
~ The apparatus according to the present invention `~ 20 thus has at least one of the electrodes provided with a coating consisting of a fibrous material with a limited electric conductivity, having a large number of outwardly extending thin fibres.
` If the electrodes are constructed, in known manner, `;~ as coaxial cylinders, it is generally sufficient for the required effect to provide the coating exclusively on the inner electrode.
In many cases, the effect of the invention is readily ; obtained to a sufficient extent when the coating only extends~ ~ -through a portion of the length of the separating space~ the -~ said portion being situated on the inlet side of the gas stream.
~ The expression "limited electric conductivity", as ' 2 -S~
used herein means that the fihrous material used for the eoatinc~
is neither a good conduetor, nor an insulator. The use of a hic~hl~ eonduetive coating only leads to a reduction of the dis--tanee between the eleetrodes, which has little or no influenee on the efficiency. If the coating consists of an insulating material, the field is exclusively determined by the electrodes, I so that the desired effect is not obtained either.
¦ A coating material naturally satisfying the required eonditions is asbestos. Asbestos is a fibrous material having j 10 a large number of outwardly projecting thin fibres, and it is .~
. somewhat, but not too strongly conductive. If the electrodes are cylindrieal, it is preferred to use a ribbon woven from asbestos fibres, which is wound on the inner electrode.
:. ~
.j J
.~' '. ., , ~.
.
, '~ ~
-' _ .
~ ".
. , .
, .
Another coating material that may be successfully used is a glass fabric of which the fibres ha~e been rendered sliyhtly conductive by the application of a conductive sizing substance.
Furthermore, good results are obtained with a coating materi~l consisting of fine metallic fibres embedded in a carrier made of a synthetic material; the met llic fibres are preferably made of stainless steel. A material o~ this kind is commercially avail-able under the trade mark "Needlona".
Finally, good results may also be obtained with a coating consis1;ing o~ a textile fabric of which the fibres have been provided with a conductive layer by vacuum deposition. Although the effec~
of the coating cannot be conclusi~ely explained, it may be presumed that an impact ionisation occurs at the beginnine f the operation of the apparatus due to the activity of the flne ou~wardly directed fibres~ and that this impact ionisation leads to B spray discharge.
When the operation of the apparatus is observed by means of a ~indow, it may be seen that a dust layer is formed on the fibres at the beginning of the separation. It may be presumed that this -dust layer forms a good base for the attachment o~ ~urther dust particles, and that the increased efficiency is due to this impro~ed attachment.
` ' Brief description Or the drawnn~ ~
~' ' .
The drawl~g sho~s ~chemAtic~1ly a preferred embodi-ment of the apparatus according to the invention.
: ', ',.
, .
. . .
`.
5~
Detailed Description.
The apparatus shown in the drawing comprises a separating space 1 bo~mded by two coaxial cylindrical electrodes, namely an outer electrode 2 and an inner-electrode 3. The gas stream to be puri~ied is supplied to the separating space 1 through an inclined inlet ~9 and leaves this space through an outlet 5 likewise placed i~
an inclined position. At the bottom, the separating space communicates with a funnel 6 for catching the separated particles, which is closed of~ by means oi an outlet member 7 to be opened from time to time to remove the separated dust.
According to the invention, the inner electrode 3 is provided9 on the side facing the outer electrode 29 wnth a coating 8 consisting o~ 2 hairy ~ibrous m~teria] ha~ing a l;mited electric conduc-tivity and a laree numer of outwardly pro3ecting thin fibres. In the embodiment as showm~ the coating 8 extends through the entire leneth o~
the separating space 1. Experiments have sho~m~ however, that the same result may be obtained in many cases by means of a coating extending ..
only throu~h a portion of the length of the separating spa~e, the said portion being situated on the inlet side of the gas stream, i.e. at the bottom in the drawing.
During experiments, a highly increased separating e~iciency was observed with r~a~erialsof the above mentioned kind, n~me-ly asbestos~ glass fibres with a conductive layer, metallic ~ibres em-b edded in a carrier, and textile ~abrics rendered conductive by vacuum deposit;on. In certain cases, the efficiency increased by the use of the ~oating from about 80% to about 95%.
.. : .
! . . . ~ . , , ' , . . . ',, ' ,: . . ' 6~
The manner in which the electrodes are supported and fed are not shown in the drawing. The conventional means may be used for these purposes.
'`
' i '~: ` ' `' !
` 20 i " .
'.' ~ '.
1~ ' , '~ ' ,,.",.. .
~ :.
~ ` ' ' - Sa -~
.
,
~ An apparatus of this kind is indicated, in practice, .~ as a dipole separator. Due to the use of a relatively low field intensity in the separating space, there is no, or substantially no ionisation in the gas stream, so that the separation is mainly based on the phenomenon that dipole charges are generated in -the particles to be removed. In order to a-ttain this effect, the field intensity in the separating space must be lower than a .1 critical value which may amount to 10-20 kV/cm when the gas stream is an air stream. The theory of dipole separation has been explained in an article by Dr. Gunter Zebel, entitled:
"Ueber die Aggregatbildung zwischen kugelformigen Aerosolteilchen ,,"~ .
mit parallel ausgerichteten Dipolmomenten" in the German ; 20 periodical "Staub", Vol. 23, Nr. 5, May 1963, pages 263-268.
A suitable construction for a dipole separator is disclosed in ~ .
U.S. Patent application No. ~47,775 which has subsequently issued July 20, 1976 to Van Dieperbrock as U.S. Patent No~
3,970,437.
West German Patent Application 594,681 ln-~e name of Prof. Dr.-Ing. Paul Denzel, published on April 29, 1971, discloses an apparatus for removing sulfur dioxide fro~ smoke gases by means of an electric field generated between two electrodes, wherein the electrodes are provided with metallic points. West-German 30 Patent Application 2,000,768 in the name of Karl Simon, published on July 2, 1971, discloses an apparatus for separating kitchen odours from an air stream, by means of an electric field . ~ .
' ~ , , ., . ' : - ' ~
.
41~9~
generated between two electrodes, wherein one of the electrodes is made of a hygroscopic material, such as paper or cardboard, impregnated with a conductive liquid.
Conventional dipole separators have the disadvantage that the separating efficiency is rather low.
The invention improves the efficiency of a dipole , separator in such a sense that a larger percentage of the particles suspended in the gas stream is removed.
According to the present invention there is provided apparatus for removing particles from a gas stream, comprising two oppositely arranged electrodes defining a separating space between them, means for leading the gas stream through said separatiny space, means for generating an electric field between ~ the said electrodes having a relatively low intensity so that `~1 substantially no ionisation occurs in the gas stream, and a -`j coating on at least one of the said electrodes, consisting ofa fibrous material with a limited electric conductivity, having a large number of outwardly projecting thin fibres.
~ The apparatus according to the present invention `~ 20 thus has at least one of the electrodes provided with a coating consisting of a fibrous material with a limited electric conductivity, having a large number of outwardly extending thin fibres.
` If the electrodes are constructed, in known manner, `;~ as coaxial cylinders, it is generally sufficient for the required effect to provide the coating exclusively on the inner electrode.
In many cases, the effect of the invention is readily ; obtained to a sufficient extent when the coating only extends~ ~ -through a portion of the length of the separating space~ the -~ said portion being situated on the inlet side of the gas stream.
~ The expression "limited electric conductivity", as ' 2 -S~
used herein means that the fihrous material used for the eoatinc~
is neither a good conduetor, nor an insulator. The use of a hic~hl~ eonduetive coating only leads to a reduction of the dis--tanee between the eleetrodes, which has little or no influenee on the efficiency. If the coating consists of an insulating material, the field is exclusively determined by the electrodes, I so that the desired effect is not obtained either.
¦ A coating material naturally satisfying the required eonditions is asbestos. Asbestos is a fibrous material having j 10 a large number of outwardly projecting thin fibres, and it is .~
. somewhat, but not too strongly conductive. If the electrodes are cylindrieal, it is preferred to use a ribbon woven from asbestos fibres, which is wound on the inner electrode.
:. ~
.j J
.~' '. ., , ~.
.
, '~ ~
-' _ .
~ ".
. , .
, .
Another coating material that may be successfully used is a glass fabric of which the fibres ha~e been rendered sliyhtly conductive by the application of a conductive sizing substance.
Furthermore, good results are obtained with a coating materi~l consisting of fine metallic fibres embedded in a carrier made of a synthetic material; the met llic fibres are preferably made of stainless steel. A material o~ this kind is commercially avail-able under the trade mark "Needlona".
Finally, good results may also be obtained with a coating consis1;ing o~ a textile fabric of which the fibres have been provided with a conductive layer by vacuum deposition. Although the effec~
of the coating cannot be conclusi~ely explained, it may be presumed that an impact ionisation occurs at the beginnine f the operation of the apparatus due to the activity of the flne ou~wardly directed fibres~ and that this impact ionisation leads to B spray discharge.
When the operation of the apparatus is observed by means of a ~indow, it may be seen that a dust layer is formed on the fibres at the beginning of the separation. It may be presumed that this -dust layer forms a good base for the attachment o~ ~urther dust particles, and that the increased efficiency is due to this impro~ed attachment.
` ' Brief description Or the drawnn~ ~
~' ' .
The drawl~g sho~s ~chemAtic~1ly a preferred embodi-ment of the apparatus according to the invention.
: ', ',.
, .
. . .
`.
5~
Detailed Description.
The apparatus shown in the drawing comprises a separating space 1 bo~mded by two coaxial cylindrical electrodes, namely an outer electrode 2 and an inner-electrode 3. The gas stream to be puri~ied is supplied to the separating space 1 through an inclined inlet ~9 and leaves this space through an outlet 5 likewise placed i~
an inclined position. At the bottom, the separating space communicates with a funnel 6 for catching the separated particles, which is closed of~ by means oi an outlet member 7 to be opened from time to time to remove the separated dust.
According to the invention, the inner electrode 3 is provided9 on the side facing the outer electrode 29 wnth a coating 8 consisting o~ 2 hairy ~ibrous m~teria] ha~ing a l;mited electric conduc-tivity and a laree numer of outwardly pro3ecting thin fibres. In the embodiment as showm~ the coating 8 extends through the entire leneth o~
the separating space 1. Experiments have sho~m~ however, that the same result may be obtained in many cases by means of a coating extending ..
only throu~h a portion of the length of the separating spa~e, the said portion being situated on the inlet side of the gas stream, i.e. at the bottom in the drawing.
During experiments, a highly increased separating e~iciency was observed with r~a~erialsof the above mentioned kind, n~me-ly asbestos~ glass fibres with a conductive layer, metallic ~ibres em-b edded in a carrier, and textile ~abrics rendered conductive by vacuum deposit;on. In certain cases, the efficiency increased by the use of the ~oating from about 80% to about 95%.
.. : .
! . . . ~ . , , ' , . . . ',, ' ,: . . ' 6~
The manner in which the electrodes are supported and fed are not shown in the drawing. The conventional means may be used for these purposes.
'`
' i '~: ` ' `' !
` 20 i " .
'.' ~ '.
1~ ' , '~ ' ,,.",.. .
~ :.
~ ` ' ' - Sa -~
.
,
Claims (9)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Apparatus for removing particles from a gas stream, comprising two oppositely arranged electrodes defining a separa-ting space between them, means for leading the gas stream through said separating space, means for generating an electric field between the said electrodes having a relatively low intensity so that substantially no ionisation occurs in the gas stream, and a coating on at least one of the said electrodes, consisting of a fibrous material with a limited electric conductivity, having a large number of outwardly projecting thin fibres.
2. Apparatus as claimed in claim 1, wherein the said electrodes are coaxial cylinders, and said coating is exclusively provided on the inner one of the said electrodes.
3. Apparatus as claimed in claim 1, wherein said coat-ing only extends through a portion of the length of said separa-ting space, said portion being situated on the inlet side of the gas stream.
4. Apparatus as claimed in claim 1, wherein said coating consists of asbestos.
5. Apparatus as claimed in claim 1, wherein said coating consists of a glass fabric of which the fibres have been treated with a conductive sizing substance.
6. Apparatus as claimed in claim 1, wherein said coating consits of fine metallic fibres embedded in a carrier made of a synthetic material.
7. Apparatus as claimed in claim 1, wherein said coating consists of a textile fabric of which the fibres have been provided with a conductive layer by vacuum deposition.
8. Apparatus as claimed in claim 4, wherein said coating consists of a ribbon woven from asbestos fibres and wound on at least one of the said electrodes.
9. Apparatus as claimed in claim 6, wherein the said metallic fibres consist of stainless steel.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL747406369A NL155199B (en) | 1974-05-13 | 1974-05-13 | DEVICE FOR THE REMOVAL OF SOLID OR LIQUID PARTICLES FROM A GAS FLOW. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1046950A true CA1046950A (en) | 1979-01-23 |
Family
ID=19821334
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA226,841A Expired CA1046950A (en) | 1974-05-13 | 1975-05-13 | Apparatus for removing particles from a gas stream |
Country Status (10)
| Country | Link |
|---|---|
| JP (1) | JPS50153367A (en) |
| CA (1) | CA1046950A (en) |
| DD (1) | DD120364A5 (en) |
| DE (1) | DE2518952A1 (en) |
| FR (1) | FR2270944B1 (en) |
| GB (1) | GB1458952A (en) |
| IT (1) | IT1032853B (en) |
| NL (1) | NL155199B (en) |
| PL (1) | PL96505B1 (en) |
| SE (1) | SE7504954L (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT377204B (en) * | 1980-11-05 | 1985-02-25 | Hans Oppitz | ELECTRODE FOR PREFERRED ELECTROSTATIC APPLICATIONS |
| DE3810910C1 (en) * | 1988-03-30 | 1989-08-10 | Johannes A. Dipl.-Wirtsch.-Ing. 7980 Ravensburg De Mueller | |
| DE4326895C1 (en) * | 1993-08-11 | 1994-08-25 | Metallgesellschaft Ag | Spray electrode for electrostatic separator, which consists of a support, on the outside of which a woven fabric is arranged, as well as use of the spray electrode |
| CA2605965C (en) | 2005-04-19 | 2012-01-03 | Ohio University | Composite discharge electrode |
| DE102009016380B4 (en) * | 2009-04-07 | 2022-08-11 | Haver & Boecker Ohg | tissue |
| US9114404B2 (en) | 2009-07-09 | 2015-08-25 | Ohio University | Carbon fiber composite discharge electrode |
-
1974
- 1974-05-13 NL NL747406369A patent/NL155199B/en not_active IP Right Cessation
-
1975
- 1975-04-29 DE DE19752518952 patent/DE2518952A1/en not_active Withdrawn
- 1975-04-29 SE SE7504954A patent/SE7504954L/en unknown
- 1975-05-05 GB GB1870475A patent/GB1458952A/en not_active Expired
- 1975-05-08 JP JP5432875A patent/JPS50153367A/ja active Pending
- 1975-05-08 DD DD185926A patent/DD120364A5/xx unknown
- 1975-05-12 PL PL1975180304A patent/PL96505B1/en unknown
- 1975-05-12 IT IT68198/75A patent/IT1032853B/en active
- 1975-05-12 FR FR7514750A patent/FR2270944B1/fr not_active Expired
- 1975-05-13 CA CA226,841A patent/CA1046950A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB1458952A (en) | 1976-12-22 |
| DE2518952A1 (en) | 1975-12-04 |
| PL96505B1 (en) | 1977-12-31 |
| JPS50153367A (en) | 1975-12-10 |
| DD120364A5 (en) | 1976-06-12 |
| FR2270944A1 (en) | 1975-12-12 |
| IT1032853B (en) | 1979-06-20 |
| NL155199B (en) | 1977-12-15 |
| SE7504954L (en) | 1975-11-14 |
| NL7406369A (en) | 1975-11-17 |
| FR2270944B1 (en) | 1979-05-18 |
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