CA1124188A - Electrostatic precipitator and discharge electrode therefor - Google Patents
Electrostatic precipitator and discharge electrode thereforInfo
- Publication number
- CA1124188A CA1124188A CA317,380A CA317380A CA1124188A CA 1124188 A CA1124188 A CA 1124188A CA 317380 A CA317380 A CA 317380A CA 1124188 A CA1124188 A CA 1124188A
- Authority
- CA
- Canada
- Prior art keywords
- discharge electrode
- protrusions
- generally
- electrode according
- elongated member
- 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
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
- B03C3/34—Constructional details or accessories or operation thereof
- B03C3/40—Electrode constructions
- B03C3/41—Ionising-electrodes
Landscapes
- Electrostatic Separation (AREA)
Abstract
ABSTRACT An improved discharge electrode for ion emission in an electrostatic precipitator comprising a generally rigid tubular member having a plurality of rounded protrusions em-bossed thereon and extending outwardly therefrom to disperse the ion emission provided by the member. In a preferred em-bodiment, the protrusions are embossed on the tubular member.
Description
~ DISCHARGE ELECTRODE THEREFOR
`~, TECHNICAL FIELD
~, The present invention relates to electrostatic ! precipitators which operate with high potential ionization ' rj impulses and in particular,to ionization and discharge j electrode members utilized therein, each in the form of a tube constituting a rigid structure having integrally formed rounded protrusions extending therefrom.
BACKGROUND ART
Ionization and discharge electrodes for electro-static precipitators for removal of suspended particles, , such as dispersed fluids, fly ash, mineral dust particles, etc., from a gas medium are well known. 5uch electrodes us~ally comprises structures in the form of wires, strips, or tubes, with corona discharge tips from which electrons migrate out into the gas to charge the particles.
..ij ,~
Electrode structures comprising rows of wires have ~een used ~raditionally, but often give rise to failure due to corrosion, fatigue, and electrical burning.
7a The burning is caused by arcing between the discharge elec-trodes and the collecting electrodes in the precipitator which results from the high potential difference therebe-tween. One well-known electrode construction of this type `30 includes a barbed wire electrode structure while another ;has a band electrode structure having discharge tips.
"`
A significant drawback to these types of electrodes is that they have no great mechanical stability and, at least in connection with the wire and thin rod type electrodes, it is often difficult to obtain a correct tension in the support-ing framework. Thus, when the electrodes are installed in .;
d L~
_ -2-1 large electrostatic precipitators, -they tend to sag or sway.
Such undesirable conditions are due to deformations and distortions which occur in the fixing of the frames, in par-ticular, when exposed to hot gases or when dust that 6 has accumulated on the electrodes are dislodged. The latter process is carried out at regular intervals by mechanical agitation of the electrodes, for example, by rapping the elec-trodes with mechanically actuated har~ers.
High mechanical stability can be obtained, however, by using another known construction which comprises a tubular carrier with a number of discharge arms having corona dis-charge tips. The discharge arms are attached to the tubular carrier, for instance by welding, and the tips are oEten 1~ spli-t to foxm a multiplicity of sharp corona discharge points.
These discharge electrodes have a significant drawback in that they give rise to frequent formation of 20 arcs between the discharge points and the collecting elec-trodes. This condition is disadvantageous in that it contributes to an irregular distribution of the powerful electrical field necessary to effect collection of the solid dust particles. The excessive arcing also results in burning 25 ~he discharge points and the discharge arms which reduces their lifetime and also gradually reduces the efficiency of the precipitator. The manufacture of such discharge elec-trodes is a time consuming and costly process particularly since a great number of discharge arms have to be mechanically 30 connected rigidly to each tubular carrier.
DISCLOSURE OF THE INVENTION
According to the present invention the above disadvantages are overcome by using a discharge electrode for ion emission in an electrostatic precipitator which r 1 comprlses a generally rigid elongated member having a plural-ity of spaced apart embossed protrusions extending outwardly therefrom to disperse the ion emission provided by -the member.
In a preferred emgodiment the elongated member is generally tubular. The protrusions form part of the tubular member and arc preferably made in a continuous embossing process. The embossing process improves the strength of the electrode and increases its mechanical stability. The protru-sions are rounded at their apices so as to avoid corrosion and electrostatic erosion. Thus they retain their relative dimen-sions and configurations.
Such a discharge electrode construction has a simple and sturdy design. It is especially suitable for an electro-static precipitator having a unidirectional collecting field and an impulse ionization field.
Furthermore, the electrode design improves the function of the precipitator in that the unidirectional poten-tial of the tube proper in relation to collecting electrodes creates a uniform field, whereas the impulse potential across the discharge electrode and the collecting electrodes via the rounded surface of the protrusions creates uniformly distri-buted clouds of ions at predetermined intervals.
In a preferred embodiment the rounded apex has aminimum radius of curvature equal to or less than the overall height of the protrusion. The rounded apex may in one form according to the invention be substantially a spherical surface.
By this relationship between the curvatures of the tube and the protrusion an advantageous distribution of the carrying field and the ionization is achieved. Furthermore~
harmful burning of the protrusions is avoided and the tendency towards the rise of flashing is largely eliminated.
., 1 In one embodiment of the invention the tube is a profiled tube composed of two or more sections joined longitudinal:Ly.
The tube may thus be comprised of a plurality of metal bands each embossed with the protrusions and then flanged or welded together in a continuous process. The joints actually improve the mechanical stability of the electrode.
In a preferred embodiment the tube is generally cylindrical, that is, a cross séction ther~of is circular.
In another preferred embodiment a cross sèction of the tube is elliptical.
In yet another preferred embodiment the tube has an angular configuration, such as square, rectangular~ etc., and is provided with protrusions along at least two of the edges. This electrode-may ba made from a single band em-bossed with rounded protrusions and bent into the required shape. Altexnatively, the electrode may be constructed by joining two or more bands together and may be shaped to ob~ain a preferred distribution of the field and the ionization.
The invention also relates to an electrostatic pre~ipitator adapted to provide high potential ionization impulses ~o create a generally unidirectional electrostatic field for removal of particulates suspended in gases directed therethrough of the type having a discharge electrode or ion 30 emission, the improvement wherein the e~ectrode is in the form of a generally rigid tubular member and having a plurality of spaced apart rounded protrusions embossed thereon and ex-tending outwardly therefrom for emitting ionization impulses into a gas stream passing thereby so as to charge particulates suspended in the gas stream for removal from the stream, the protrusions being arranged in spaced relation. The rounded configurations of the protrusions and the spacing thereof .
' r .... , ~
L~
__ -5-1 are such as to provide dispersion of the ionic emission provided by the member.
BRIEF DESCRIPTION OF THE DRAWINGS
~ 5 ~ xamples of discharge electrodes of the invention will now be described with reference to the accompanying drawings, in which:
Fig. l is a side elevation of a first discharge 10 electrode;
Fig. 2 is a section o~ the discharge electrode taken along lines 2-2 of Fig. l;
Fig. 3 is a side elevation of another discharge electrode having an elliptical configuration;
15 Fig. 4 is a section view taken along lines 4-4 of Fig. 3;
Fig. 5 is a side elevation of a third discharge electrode having an angular configuration; and Fig. 6 is a section ta]cen along lines 6 6 of Fig.
`: BEST MODE FOR CARRYING OUT THE INVENTION
The discharge electrodes according to the examples 25 illustrated in the drawings comprise a tubular carrier lhaving a number of protrusions 2 with a rounded apex 3, out-wardly directed from the tu~ular carrier. Ordinarily such discharge electrodes are suspended from a common frame (not shown) in parallel rows between plate-like collection elec-30 trodes in a known manner. The suspension of the electrodeson the precipitator housing has thereforenot been illustrated.
Referring to Figs. l and 2, the tubular carrier l has a rigid construction, which is able to withstand mech-35 anic~l vibrations and may carry any suitable number ofprotrusions 2. These protrusions 2 are embossed in the tube wall proper and are thus integral with the tube.
_ -6-1 The tube can have various cross-sections as illustrated in the examples shown in the drawings and may be formed in one slngle section or in a number of sections flanged or welded together longitudinally.
The embodiment illustrated in Figs. 3 and 4 shows a tubular carrier 11 having an elliptical cross-section and protrusions 12 each with rounded apex 13 arranged along opposite lines intersecting the major axis of the ellipse.
1~ The protrusions 12 may be oriented in a plane which may be parallel or perpendicular to the direction of the collecting electrodes in order to obtain a preferred directional dis-tribution of ionization.
The embodiment illustrated in Figs. 5 and 6 shows one form of an angular tubular carrier 21 having protrusions 22 each with rounded apex 23.
The electrode according to the invention may be 20 used in electrostatic precipitators having a unidirectional field generated by a unidirectional voltage and an ionization field generated by an impulse voltage. The unidirectional voltage is usually below the voltage limit causing flash-overs in the precipitator, whereas the impulse voltage 25 generally is above this limit.
sy means of the electrodes, the unidirectional ield which serves as a transport field for the suspended particles or dispersed fluid, is uniformly distributed over the surface 30 Of the tubular structure~ whereas the ionization field is directed outwards from the protrusions. Thus, the arrange-ment of the protrusions determines distribution of the ionization. The rounded form of the apex of the protrusions ensures that distribution of the ionization is from a sub-35 stan~ial part of the surface of each protrusion while ~3f~r~
1 confining the ionization to occur from particular areas of the discharge electrocle.
The duration of the impulses will be so short that 5 flashing is avoided, but effective charging of the dust particles is achieved.
.:
`~, TECHNICAL FIELD
~, The present invention relates to electrostatic ! precipitators which operate with high potential ionization ' rj impulses and in particular,to ionization and discharge j electrode members utilized therein, each in the form of a tube constituting a rigid structure having integrally formed rounded protrusions extending therefrom.
BACKGROUND ART
Ionization and discharge electrodes for electro-static precipitators for removal of suspended particles, , such as dispersed fluids, fly ash, mineral dust particles, etc., from a gas medium are well known. 5uch electrodes us~ally comprises structures in the form of wires, strips, or tubes, with corona discharge tips from which electrons migrate out into the gas to charge the particles.
..ij ,~
Electrode structures comprising rows of wires have ~een used ~raditionally, but often give rise to failure due to corrosion, fatigue, and electrical burning.
7a The burning is caused by arcing between the discharge elec-trodes and the collecting electrodes in the precipitator which results from the high potential difference therebe-tween. One well-known electrode construction of this type `30 includes a barbed wire electrode structure while another ;has a band electrode structure having discharge tips.
"`
A significant drawback to these types of electrodes is that they have no great mechanical stability and, at least in connection with the wire and thin rod type electrodes, it is often difficult to obtain a correct tension in the support-ing framework. Thus, when the electrodes are installed in .;
d L~
_ -2-1 large electrostatic precipitators, -they tend to sag or sway.
Such undesirable conditions are due to deformations and distortions which occur in the fixing of the frames, in par-ticular, when exposed to hot gases or when dust that 6 has accumulated on the electrodes are dislodged. The latter process is carried out at regular intervals by mechanical agitation of the electrodes, for example, by rapping the elec-trodes with mechanically actuated har~ers.
High mechanical stability can be obtained, however, by using another known construction which comprises a tubular carrier with a number of discharge arms having corona dis-charge tips. The discharge arms are attached to the tubular carrier, for instance by welding, and the tips are oEten 1~ spli-t to foxm a multiplicity of sharp corona discharge points.
These discharge electrodes have a significant drawback in that they give rise to frequent formation of 20 arcs between the discharge points and the collecting elec-trodes. This condition is disadvantageous in that it contributes to an irregular distribution of the powerful electrical field necessary to effect collection of the solid dust particles. The excessive arcing also results in burning 25 ~he discharge points and the discharge arms which reduces their lifetime and also gradually reduces the efficiency of the precipitator. The manufacture of such discharge elec-trodes is a time consuming and costly process particularly since a great number of discharge arms have to be mechanically 30 connected rigidly to each tubular carrier.
DISCLOSURE OF THE INVENTION
According to the present invention the above disadvantages are overcome by using a discharge electrode for ion emission in an electrostatic precipitator which r 1 comprlses a generally rigid elongated member having a plural-ity of spaced apart embossed protrusions extending outwardly therefrom to disperse the ion emission provided by -the member.
In a preferred emgodiment the elongated member is generally tubular. The protrusions form part of the tubular member and arc preferably made in a continuous embossing process. The embossing process improves the strength of the electrode and increases its mechanical stability. The protru-sions are rounded at their apices so as to avoid corrosion and electrostatic erosion. Thus they retain their relative dimen-sions and configurations.
Such a discharge electrode construction has a simple and sturdy design. It is especially suitable for an electro-static precipitator having a unidirectional collecting field and an impulse ionization field.
Furthermore, the electrode design improves the function of the precipitator in that the unidirectional poten-tial of the tube proper in relation to collecting electrodes creates a uniform field, whereas the impulse potential across the discharge electrode and the collecting electrodes via the rounded surface of the protrusions creates uniformly distri-buted clouds of ions at predetermined intervals.
In a preferred embodiment the rounded apex has aminimum radius of curvature equal to or less than the overall height of the protrusion. The rounded apex may in one form according to the invention be substantially a spherical surface.
By this relationship between the curvatures of the tube and the protrusion an advantageous distribution of the carrying field and the ionization is achieved. Furthermore~
harmful burning of the protrusions is avoided and the tendency towards the rise of flashing is largely eliminated.
., 1 In one embodiment of the invention the tube is a profiled tube composed of two or more sections joined longitudinal:Ly.
The tube may thus be comprised of a plurality of metal bands each embossed with the protrusions and then flanged or welded together in a continuous process. The joints actually improve the mechanical stability of the electrode.
In a preferred embodiment the tube is generally cylindrical, that is, a cross séction ther~of is circular.
In another preferred embodiment a cross sèction of the tube is elliptical.
In yet another preferred embodiment the tube has an angular configuration, such as square, rectangular~ etc., and is provided with protrusions along at least two of the edges. This electrode-may ba made from a single band em-bossed with rounded protrusions and bent into the required shape. Altexnatively, the electrode may be constructed by joining two or more bands together and may be shaped to ob~ain a preferred distribution of the field and the ionization.
The invention also relates to an electrostatic pre~ipitator adapted to provide high potential ionization impulses ~o create a generally unidirectional electrostatic field for removal of particulates suspended in gases directed therethrough of the type having a discharge electrode or ion 30 emission, the improvement wherein the e~ectrode is in the form of a generally rigid tubular member and having a plurality of spaced apart rounded protrusions embossed thereon and ex-tending outwardly therefrom for emitting ionization impulses into a gas stream passing thereby so as to charge particulates suspended in the gas stream for removal from the stream, the protrusions being arranged in spaced relation. The rounded configurations of the protrusions and the spacing thereof .
' r .... , ~
L~
__ -5-1 are such as to provide dispersion of the ionic emission provided by the member.
BRIEF DESCRIPTION OF THE DRAWINGS
~ 5 ~ xamples of discharge electrodes of the invention will now be described with reference to the accompanying drawings, in which:
Fig. l is a side elevation of a first discharge 10 electrode;
Fig. 2 is a section o~ the discharge electrode taken along lines 2-2 of Fig. l;
Fig. 3 is a side elevation of another discharge electrode having an elliptical configuration;
15 Fig. 4 is a section view taken along lines 4-4 of Fig. 3;
Fig. 5 is a side elevation of a third discharge electrode having an angular configuration; and Fig. 6 is a section ta]cen along lines 6 6 of Fig.
`: BEST MODE FOR CARRYING OUT THE INVENTION
The discharge electrodes according to the examples 25 illustrated in the drawings comprise a tubular carrier lhaving a number of protrusions 2 with a rounded apex 3, out-wardly directed from the tu~ular carrier. Ordinarily such discharge electrodes are suspended from a common frame (not shown) in parallel rows between plate-like collection elec-30 trodes in a known manner. The suspension of the electrodeson the precipitator housing has thereforenot been illustrated.
Referring to Figs. l and 2, the tubular carrier l has a rigid construction, which is able to withstand mech-35 anic~l vibrations and may carry any suitable number ofprotrusions 2. These protrusions 2 are embossed in the tube wall proper and are thus integral with the tube.
_ -6-1 The tube can have various cross-sections as illustrated in the examples shown in the drawings and may be formed in one slngle section or in a number of sections flanged or welded together longitudinally.
The embodiment illustrated in Figs. 3 and 4 shows a tubular carrier 11 having an elliptical cross-section and protrusions 12 each with rounded apex 13 arranged along opposite lines intersecting the major axis of the ellipse.
1~ The protrusions 12 may be oriented in a plane which may be parallel or perpendicular to the direction of the collecting electrodes in order to obtain a preferred directional dis-tribution of ionization.
The embodiment illustrated in Figs. 5 and 6 shows one form of an angular tubular carrier 21 having protrusions 22 each with rounded apex 23.
The electrode according to the invention may be 20 used in electrostatic precipitators having a unidirectional field generated by a unidirectional voltage and an ionization field generated by an impulse voltage. The unidirectional voltage is usually below the voltage limit causing flash-overs in the precipitator, whereas the impulse voltage 25 generally is above this limit.
sy means of the electrodes, the unidirectional ield which serves as a transport field for the suspended particles or dispersed fluid, is uniformly distributed over the surface 30 Of the tubular structure~ whereas the ionization field is directed outwards from the protrusions. Thus, the arrange-ment of the protrusions determines distribution of the ionization. The rounded form of the apex of the protrusions ensures that distribution of the ionization is from a sub-35 stan~ial part of the surface of each protrusion while ~3f~r~
1 confining the ionization to occur from particular areas of the discharge electrocle.
The duration of the impulses will be so short that 5 flashing is avoided, but effective charging of the dust particles is achieved.
.:
Claims (12)
1. A discharge electrode for ion emission in an electrostatic precipitator which comprises a generally rigid tubular elongated member having a plurality of generally rounded protrusions embossed thereon and formed integrally therewith and extending outwardly therefrom for emitting ionization impulses into a gas stream passing thereby so as to charge particulates in said gas stream for removal there-from, said protrusions being arranged in spaced relation along said elongated member, said integral protrusions having a predetermined generally rounded configuration and being spaced apart so as to provide improved rigidity of the tubular member and uniform dispersion of the ionic emission provided by said member.
2. A discharge electrode according to Claim 1 wherein said elongated member has a generally circular cross sectional configuration.
3. A discharge electrode according to Claim 2 wherein said spaced apart protrusions are arranged at peri-pheral portions of said elongated member along two generally opposed axial lines of at least one plane, wherein said plane has a line generally coincident with the central axis of said elongated member.
4. A discharge electrode according to Claim 1 wherein said elongated member has a generally elliptical cross section configuration.
5. A discharge electrode according to Claim 4 wherein said protrusions are arranged along peripheral portions of said elongated member in intersecting relation to the major axis of the ellipse.
6. A discharge electrode according to Claim 1 wherein said elongated member has a generally polygonal cross sectional configuration.
7. A discharge electrode according to Claim 6 wherein said protrusions are provided along at least two edge portions of said elongated member.
8. A discharge electrode according to Claim 1 wherein said protrusion has a rounded apex.
9. A discharge electrode according to Claim 8 wherein the minimum radius of curvature of said apex is at least equal to the height of the protrusion.
10. A discharge electrode according to Claim 8 wherein said protrusion has a generally spherical cross sectional configuration.
11. A unitary discharge electrode for ion emission in an electrostatic precipitator adapted to provide high potential electrostatic impulses, which comprises a generally rigid tubular member having a plurality of spaced apart rounded protrusions embossed thereon and formed integrally therewith and extending outwardly therefrom for emitting ionization impulses into a gas stream passing thereby so as to charge particulates suspended in said gas stream for removal of said charged particulates from said stream, said integral protrusions having a predetermined generally rounded configuration and being spaced apart so as to provide improved rigidity of the tubular member and uniform dispersion of the ionic emission provided by said member.
12. In an electrostatic precipitator adapted to provide a substantially unidirectional electrostatic field generated by a high unidirectional voltage and an ionization field generated by an impulse voltage for removal of particulates suspended in gases directed therethrough of the type having at least one discharge electrode for ion emission, the improvement wherein said electrode is in the form of a generally rigid tubular member having a plurality of spaced apart rounded protrusions embossed thereon and formed integrally therewith and extending outwardly therefrom for emitting ionization impulses into a gas stream passing thereby so as to charge particulates suspended in said gas stream for removal of said charged particulates from said steam, said integral protrusions having a predetermined generally rounded configuration and being spaced apart so as to provide improved rigidity of the tubular member and uniform dispersion of the ionic emission provided by said member substantially from said protrusions.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB51321/77 | 1977-12-09 | ||
| GB5132177 | 1977-12-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1124188A true CA1124188A (en) | 1982-05-25 |
Family
ID=10459535
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA317,380A Expired CA1124188A (en) | 1977-12-09 | 1978-12-05 | Electrostatic precipitator and discharge electrode therefor |
Country Status (3)
| Country | Link |
|---|---|
| BE (1) | BE872628A (en) |
| CA (1) | CA1124188A (en) |
| ZA (1) | ZA786756B (en) |
-
1978
- 1978-12-01 ZA ZA00786756A patent/ZA786756B/en unknown
- 1978-12-05 CA CA317,380A patent/CA1124188A/en not_active Expired
- 1978-12-08 BE BE192214A patent/BE872628A/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| ZA786756B (en) | 1979-10-31 |
| BE872628A (en) | 1979-03-30 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry | ||
| MKEX | Expiry |
Effective date: 19990525 |