CA1102257A - Focusing electrodes for high-intensity ionizer stage of electrostatic precipitator - Google Patents
Focusing electrodes for high-intensity ionizer stage of electrostatic precipitatorInfo
- Publication number
- CA1102257A CA1102257A CA286,553A CA286553A CA1102257A CA 1102257 A CA1102257 A CA 1102257A CA 286553 A CA286553 A CA 286553A CA 1102257 A CA1102257 A CA 1102257A
- Authority
- CA
- Canada
- Prior art keywords
- discharge electrode
- venturi
- disc
- focusing electrodes
- electrode
- 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
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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
- B03C3/36—Controlling flow of gases or vapour
-
- 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
- B03C3/38—Particle charging or ionising stations, e.g. using electric discharge, radioactive radiation or flames
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- Electrostatic Separation (AREA)
- Elimination Of Static Electricity (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An improved electrode assembly for a high-inten-sity ionizer array utilized as the first stage in a two-stage electrostatic precipitator. Each ionizer unit employs a pair of co-axial electrodes to create a high-intensity electric field across the path of a particulate-laden gas stream. As the gas passes through the field, it is in tensely ionized and the particulate becomes highly charged.
The ionizer anode comprises a venturi diffuser through which the gas stream flows immediately prior to entry into a precipitator stage which removes the charged particles. The ionizer cathode is a disc co-axially mounted within the venturi throat and having an arcuate periphery. A high voltage power supply connected between the anode and cathode establishes a high-intensity corona discharge in the annular region formed between the edge of the cathode disc and the surrounding cylindrical anode surface. Focusing electrodes at cathode potential are positioned on either side of the cathode disc and intensify the electric field along the anode wall at the fringes of the current flux band upstream and downstream from the corona discharge plane. This substantially reduces the width of the anode surface sub-jected to corona current and minimizes anode cleaning requirements by reducing the particle deposition area.
An improved electrode assembly for a high-inten-sity ionizer array utilized as the first stage in a two-stage electrostatic precipitator. Each ionizer unit employs a pair of co-axial electrodes to create a high-intensity electric field across the path of a particulate-laden gas stream. As the gas passes through the field, it is in tensely ionized and the particulate becomes highly charged.
The ionizer anode comprises a venturi diffuser through which the gas stream flows immediately prior to entry into a precipitator stage which removes the charged particles. The ionizer cathode is a disc co-axially mounted within the venturi throat and having an arcuate periphery. A high voltage power supply connected between the anode and cathode establishes a high-intensity corona discharge in the annular region formed between the edge of the cathode disc and the surrounding cylindrical anode surface. Focusing electrodes at cathode potential are positioned on either side of the cathode disc and intensify the electric field along the anode wall at the fringes of the current flux band upstream and downstream from the corona discharge plane. This substantially reduces the width of the anode surface sub-jected to corona current and minimizes anode cleaning requirements by reducing the particle deposition area.
Description
llO;~Z57' l l 31 The present invention relates to high-intensit~ io-4l nizers which pre-char~e particulate matter entrain~ in a con-taminated cJas stream prior to removal o the charqed particles from the stre~n ~y electrostatic precipitation~ More specifi-7 ¦ cally, the invention is directed to an improved ele~trode con-8 figuration for a co-axial venturi ionizer ~Iherein focusing elec-9¦ trodes narrow the width of the curren~ flux band unstream and ¦ downstream of the ionizer discharge plane.
12 Stanards for emissions of particulate in flue gases ~3 ! issuing fror~ coal fired electrical power station stac~.s are 14 becorning incr~asingly mor~e stringentO Current air quality stan-151 daras require that more than 99~ of the fly ash produced by 161 burning cOal be rernoved prior to discharge o~ the co~bustior.
~7-¦ gases rom the stack. ~hus~ the efficienc~ of particulate col-18 lection ~ust increase in propor~ion ~o the ash con~ent of the 19 co~lO ~n adfiition, in an effort ~o reduce the e~ission of cer-tain gaseous pollutants, particularly ~he sulfur o~;ides, it has 21 beccme increasingly necessarv to use low sulfur co.~7 in elec-22 trical power generatir.g plantsO
23 Tha electrostatic precipitator is the ~ost co~nonly 24 used device for ~he removal of particulate matter from po~lex station stac3. gascS~ Because the size of an electrostat~c pre-26 cipitator is ~etermined by ~he e~ficiencv vf fly ash removal
12 Stanards for emissions of particulate in flue gases ~3 ! issuing fror~ coal fired electrical power station stac~.s are 14 becorning incr~asingly mor~e stringentO Current air quality stan-151 daras require that more than 99~ of the fly ash produced by 161 burning cOal be rernoved prior to discharge o~ the co~bustior.
~7-¦ gases rom the stack. ~hus~ the efficienc~ of particulate col-18 lection ~ust increase in propor~ion ~o the ash con~ent of the 19 co~lO ~n adfiition, in an effort ~o reduce the e~ission of cer-tain gaseous pollutants, particularly ~he sulfur o~;ides, it has 21 beccme increasingly necessarv to use low sulfur co.~7 in elec-22 trical power generatir.g plantsO
23 Tha electrostatic precipitator is the ~ost co~nonly 24 used device for ~he removal of particulate matter from po~lex station stac3. gascS~ Because the size of an electrostat~c pre-26 cipitator is ~etermined by ~he e~ficiencv vf fly ash removal
2? re~uired, an i~cr~ase in required f.ly ash collec~ion efflcienc~
28 reauires a corxesponding increase in equip~ent si~e and costO
29 Moreover, becauc;~ fly ash resi~tivity tencls to be ir.versely relatcd to ~he l~vel of cornbustible sulfux in th~ coal burned, 31 the use of lo~ sulfur coals ~o direc~ly r~duce iJaseous suleur ,, ., ".
.
... .
1 o:cide emissions~ produces highly resistive dusts. It has been 2 demonstra~ed that the size of the electros~atic pr~cipitator
28 reauires a corxesponding increase in equip~ent si~e and costO
29 Moreover, becauc;~ fly ash resi~tivity tencls to be ir.versely relatcd to ~he l~vel of cornbustible sulfux in th~ coal burned, 31 the use of lo~ sulfur coals ~o direc~ly r~duce iJaseous suleur ,, ., ".
.
... .
1 o:cide emissions~ produces highly resistive dusts. It has been 2 demonstra~ed that the size of the electros~atic pr~cipitator
3 necessary to achieve a given level of collection efficienc~
4 increases with increasing electrical resistivity of the fly 6 ash. -~he use of low sulfur coals therefore ~urther increases 6 the size and cost of t~e precipitatorO
7 - ~ecently, high-intensity ioniæers have been developed 8 in which a unique electrode seometry produces a stable high-9 intensity corona discharge ~hrough which t~e part~culate-laden 10 sas is passea. The ionized flue gases producèd charge the 11 particulate matter ~o a much higher level than is achievable .
12 ~ith a con~entional electrostatic precipita~or. When the ionizex 13 is followed with an electrostatic precipitator, the higher pax-14 ticle charse results in a higher collection efficiency in the 15 precipita~or due to h~gher migration or particle drift velocity~ .
16 In sucn a two-stage arrangement, the ionizer ac~s as the charging 17 stage and ~he precipi~at~r serves as the collectina stageO
18 Such high-intensity ioni~ers utilize a co-axial pair :-1q1 or electrodes ~o generate a high-intensity field e:~panaing ra~ially 201 and axially parallel to the direction o~ gas flo~ The anode in 21 1 such an arrangemen~ typicallv takes the orm of a venturi di~fuser 22¦ thxoua,h which the StAC~ gases f1ow im~ediatelv prior to entering . .
231 the precipitator stage. The cathode is a ~isl~ co-a~ially mounted 24¦ within the venturi throat and is formed with a curved peripileral ¦ . i ! i ~ : , 25 ¦ edge h~ina a radiusi much s~,aller than the i~ner radius o ~he 26 ¦venturiO When a high v~ltage po~er supply isi connected between 27 ¦~he anode ana ca~hode " a high-intensity coxona discharge is ~81 establi~hed in an annular region he~ween the arcua~e periphery 29 of 'che ca~hode dis3c and lthe surrounding c:yl1ndrical anode sur-30 1~/ .
3'11 //~ ` ' , ,32 1 /// , , ~ , , ¦ ~ 3 ~ ~
l ; ! : ~ ~ l ~ ' '; . ' ,' ` : ' . .
i7 face near the disc. Because the field is relatively narrow in the direction of gas flow, a high intensity fieLd is achievable without prohibitive electrical power require-ments. The combination of high gas stream velocity through the venturi and the high intensity transverse electric field through which the gas stream passes produces intense ioniza-tion and very high levels of charge on the particles and results in increased collection efficiency notwithstanding the high resistivity of the particulate as in the case of fly ash from low sulfur coal.
One of the problems which has been encountered in connection with co-axial high intensity ionizers of the type described above results from the detrimental ~uild-up of charged particles on the cylindrical anode waIl near the corona discharge plane. Deposition of high resistivity particulate matter in this region results in the phenomena of back corona and excessive sparking with a resulting deterioration in the applied electric field and attendant degradation in particle charging efficiency~ Prior attempts to o~ercome this problem have involved "cleaning" the anode surface in the affected region to eliminate disturbances in the corona due to contaminant build-up on the outer elect-rode. One form of anode cleaning involves the injection of clean gas into the venturi in the corona discharge region to form a protective barrier between the anode wall and the charged particles 1n the gas stream. One particularl~
effect1ve clean gas injection system is described in U.S.
patent 4,108,615 issued August 22, 1978.
According to the present invention, anode cleaning requirements referred to above are reduced by substantially ?~ ~
~ .
,, , -: .,~' ',. .,', .':', ~' : ~ . ,. :, . .
. , ,: . . .
narrowing the width of the current flux band in the annular region between the cathode and anode.
More specifically the invention is a high-in-: tensity gas ionizer comprising: a venturi through which particulate laden gas may flow; a single discharge electrode mounted within the throat of the venturi and having a peri-pheral edge defining a maximum dimension transverse to -the direction of the gas flow; voltage means interconnecte~
between the discharge electrode and the venturi to establish a high-intensity electric field within the ~enturi across the gas flow, the peripheral edge of the discharge electrode having at least one profile-of sufficient curvature that the electric field establishes a corona current in a region between the discharge electrode and the venturi; and first and second cylindrical focusing electrodes mounted along the direction of the gas flow within the venturi, extending coaxially in the first and second directions away from the discharge electrode, being electrically coupled to the discharge electrode and maintained at approximately the same electrical potential as the discharge electrode, having respective diameters less than the maximum transverse dimension of the discharge electrode, and being sized so that corona discharge from the focusing electrodes is substantially non-existent; the first and second focusing electrodes being sized to increase the electric field strength at the fringes of the region of corona current to ~axially limit the region of corona current and thus reduce the surface area of the venturi subjected to collection of particulates in the gas.
;.'~. ' ` ~:
.
.
Desirably the discharge electrode comprises a cathode disc having an arcuate periphery and being co-axially mounted within said venturi and wherein said fo-cusing electrodes comprise cylindrical members on either side of said disc and co-axial therewith. The focusing electrodes on either side of the cathode disc create higher electric fields at the fringes of the current flux band upstream and downstream of the ionizer discharge plane and thus narrow the width of the current flux band in the above annular region. The higher electric fields drive the ions to the anode with higher velocity with a consequent reduc-tion of ion migration upstream and downstream by a mutual repulsion. The net effect is that the width of the band on the anode surface which is subject to particle deposition is reduc~d substantially along with cleaning gas requirements.
The focusing electrodes are sized to provide a high electric field near the anode surface at the fringes of the current flux band by extending circular electrodes on either side o~ the cathode disc a distance approximately equal to the inter-electrode gap between the cathode per-iphery and surrounding anode wall. The downstream focusing electrode cylinder can be terminated beyond that distance by a hemispherical cap. The diameter of the focusing electrode cylinders is preferably between 20% and 40% of the anode inside diameter but not larger than the cathode diameter.
In a further aspect the invention is a method of narrowing the current flux band in a coaxial electrode -5a-~... .
high-intensity gas ionizer including a central cathode element surrounded by a cylindrical anode surface comprising \ the step of generating an increased electrical field having ~ ~ a strength less than the strength required to initiate `~ 5 corona discharge, in a region on both sides of the cathode element extending coaxially away from the cathode element by a distance at least equal to the distance between the cathode element periphery and the cylindrical anode surface, to increase the velocity of ions travelling toward the anode surface~ thereby reducing the amount of ion migration in an axial direction.
The invention is illustrated, by way of example, in the drawings, in which:
Figure 1 is a schematic side elevational view ; 15 illustrating a multi-stage electrostatic precipitator incorporating a high-intensity ionizer according to the present invention;
Figure 2 is an enlarged side view of one ionizer : stage of the apparatus of Figure 1 partially broken away to show the ionizer array;
~ Figure 3 is an end elevational view of the ionizer stage of Figure 2 with the inlet partially broken away to show the ionizer array; .
Figure 4, on the first page of the drawings, is an enlarged partial sectional view of a single ionizer venturi illustrating the electrode arrangement.
' , -5b-.
i7 Turning now to the drawings, Figure 1 shows in schematic side elevational view an electrostatic preci-pitator system incorporating the invention. As seen in this Figure, the precipitator system includes a gas inlet 11 into which gases to be cleaned are directed as sugyested by arrow 12, a gas outlet 13 from which cleaned gases are supplied to appropriate downstream apparatus, e.g. an atmospheric discharge duct, as suggested by arrow 14, and typically a cascaded pair of ionizer-precipitator units generally designated by reference numerals 15, 15'. ~ach ionizer-precipitator unit 15, 15' includes an ionizer stage 16 (16') and typically a pair of conventional electrostatic precipi-tators 17, 18 (17', 18'). Each ionizer stage 16, 16' and precipitator stage 17, 17', 18, 18' is provided with a high voltage input connector 19 coupled to a suitable source of high voltage as described more full~ below and a collecting bin portion 20 for collecting particulate matter precipi-tated from the gas as the latter flows through units 15, 15'.
In operation, gases containing particulate matter enter the Figure 1 apparatus via inlet 11 and pass through the first ionizer stage 16 in which the particles in the gas are electrostatically charged. The gas bearing the elec-trostatically charged particles next flows into successive precipitatox stages 17, 18 in each of which the charged particles are deflected out of the flow path of the gas under the influence of an electrical field established across the flow path, the particles being deposited in the bin portions 20 of the precipitator stages 17, 18. The gas exiting from precipitator 18 is passed through ioni~er stage 16', and precipitator stages 17', 18', to provide additional --6~
X
cleaning therefor, and the cleaned gases emerging from precipitator stage 18' are conducted via gas outlet 13 to appropriate downstream apparatus.
Figures 2 and 3 typically illustrate the gas inlet 11 and the first ionizer stage 16 with more detail~ As seen in these Figures, gas inlet 11 comprises a hollow conduit of trapezoidal or other suitable geometric configuration which is coupled at the downstream side to a gas distributor portion 22. Distributor portion 22 is coupled to an entry chamber 23 formed within the housing of ionlzing unit 16 by the side and bottom walls thereof and a vertically arranged bulkhead 24.
Positioned within the ionizer stage 16 in a regular array are a plurality of venturi diffusers 27 and associated central electrode support members 28 each projecting into either end of the associated venturi 27 (shown here up-stream) and substantially coaxially therewith. Each member 28 is coupled to a bus bar network generally designated by reference numeral 29 and consisting of vertically arranged parallel bus bars (three shown here) interconnected at the upper ends thereof by a common bus bar element 31, the element 31 being connected to a single bus bar element 32 extending from the interior of ionizer stage 16 to an exter-nal conventional high voltage connector shroud 33 to which a high voltage is supplied from a suitable power source (not shown) via high voltage connector 34. The downstream end or outlet of each venturi 27 .is coupled to an exit chamber 36 which is in turn coupled to the inlet of electrostatic precipitator stage 17.
Storage bin 20 is provided with a removable door X
40 for purposes of inspection and cleaning, and a vibrator bracket 41 for permitting the use of an optional conven-tional vibxator to assist in settling any particulate matter collecting in bin 20 towards the bottom edge 42 thereof.
Bottom edge 42 is provided with suita~le apertures (not shown) for enabling the particulate matter to be removed ~rom the bin 20 in a conventional manner. Bins 20 o the remaining system elements 16', 17, 17', 18, and 18' are con~igured in a substantially identical manner.
Each venturi element 27 and associated coaxial member 28 generally comprises an electrode pair for generating a high intensity electric field across the path of gas ~low through the ionizer stage 16. For this purpose, an elec-trode (described below) is carried by each member 28 and is coupled to a source of relatively high negative potential, via bus bar network 29 while each venturi conduit 27 is coupled via the framework o~ the structure to ground poten-tial. Thus each venturi 27 serves as an anode and each - member 28 serves as a cathode support.
In operation, with high voltage applied between ` the cathode and anode, particles suspended in any gas flowing through the ioinzer stage 16 are electrostatically ; charged when passing through the throat of venturi 27. In order to ensure that substantially all charged particles remain suspended in the flowing gas until arriving at the ; downstream precipitator 17 or 18, and do not adhere to the ground potential anode su~face, the novel electrode con~i ;
guration shown in Figure 4 is employed.
With reference to Figure 4, each venturi element 27 is ~ormed with an inwardly tapering conical inlek section -~ :
~, .
X
, '' :, ':
45, a generally cylindrical central section or throat 46 and an outwardly tapering conical outlet portion 47. The cathode includes a conducting disc 50 having a curved peripheral edge which projects outwardly from the outer surface of member 28. Disc 50 is mounted substantially coaxially in the throat of venturi 27 and provides a highly constricted high-intensity electric ~ield in the form of a corona discharge between the curved periphery of disc 50 and the surrounding anode surface 52 when a high poten~ial is applied.
Mounted on either side of cathode disc 50 are focusing electrodes 53 and 54. These electrodes are pre-ferably of cylindrical cross-section and are co-axial with cathode disc 50. Electrodes 53 and 54 are mounted to be in electrical contact with cathode disc 50 and thus are at cathode potential. Upstream focusing electrode 53 may be formed by appropriately sizing electrode support member 28 and maintaining electrical continuity between cathode disc 50, member 28, and bus bar 29. In this case, the downstream end of support member 28 functions as the upstream focusing electrode 53. Downstream focusing electrode 54 may be formed as an extension of support member 28 which extends a sufficient distance downstream of cathode disc 50 and is preferably terminated by a hemispherically shaped end 25 surface 54a. Electrode 54 may be attached to electrode 53 by a threaded stud projecting Erom electrode 54 and passing through the center of cathode disc 50 into support member 28.
Focusing electrodes 53 and 54 increase the strength of the electric field at the fringes of the discharge current _9_ , Z~i7 flux band (indicated at 56) upstream and downstream of the ionizer discharge plane. The increased electrical field in these areas drives the ions to the anode with higher velocity.
Therefore, the ions migrate less upstream and downstream in their expansion by mutual replusion. The net effect is that the width of the current flux band impinging on the anode surface is reduced substantially and the amount of anode surface which must be cleaned is similarly reduced. This in turn reduces cleaning gas requirements and results in an overall increase in particulate collection efficiency.
Focusing electrodes 53 and 54 extend upstream and downstream from cathode disc 50 a distance approximately equal to the inter-electrode separation between tha periphery of cathode disc 50 and the surrounding anode wall. For purposes of the invention, the focusing electrode cylinders can be terminated beyond tha~ distance if desired such as by hemispherically capping the downstream cylinder 54 as described above to prevent corona leakage there, however, extension of the electrode beyond that distance will still provide satisfactory results as indicated by the fact that the physical structure of eIectrode 53 is formed in the depicted embodiment by cathode support element 28 which extends out of the inlet side of venturi 27 terminating at bus bar 2g.
The diameter of the focusing electrode cylinders is preferably between 0.2 and 0.~ of the inside diameter of the anode surface surrounding cathode disc 50. If the diameter is larger or smaller the electric field at the focusing electrode surface is increased promoting surface corona leakage. Eowever, even outside the preferred range, focusing electrodes of the present invention provide improve---10-- ., Z~i~i7 d performance as compared with prior art devices not employ-ing such electrodes.
While a pre~erred embodiment of the present invention has been shown and described above, it will be readily apparent to those skilled in the art that numerous modifications and adaptations thereof may be made without departing from the spirit and scope of the invention as defined by the following claims.
.
7 - ~ecently, high-intensity ioniæers have been developed 8 in which a unique electrode seometry produces a stable high-9 intensity corona discharge ~hrough which t~e part~culate-laden 10 sas is passea. The ionized flue gases producèd charge the 11 particulate matter ~o a much higher level than is achievable .
12 ~ith a con~entional electrostatic precipita~or. When the ionizex 13 is followed with an electrostatic precipitator, the higher pax-14 ticle charse results in a higher collection efficiency in the 15 precipita~or due to h~gher migration or particle drift velocity~ .
16 In sucn a two-stage arrangement, the ionizer ac~s as the charging 17 stage and ~he precipi~at~r serves as the collectina stageO
18 Such high-intensity ioni~ers utilize a co-axial pair :-1q1 or electrodes ~o generate a high-intensity field e:~panaing ra~ially 201 and axially parallel to the direction o~ gas flo~ The anode in 21 1 such an arrangemen~ typicallv takes the orm of a venturi di~fuser 22¦ thxoua,h which the StAC~ gases f1ow im~ediatelv prior to entering . .
231 the precipitator stage. The cathode is a ~isl~ co-a~ially mounted 24¦ within the venturi throat and is formed with a curved peripileral ¦ . i ! i ~ : , 25 ¦ edge h~ina a radiusi much s~,aller than the i~ner radius o ~he 26 ¦venturiO When a high v~ltage po~er supply isi connected between 27 ¦~he anode ana ca~hode " a high-intensity coxona discharge is ~81 establi~hed in an annular region he~ween the arcua~e periphery 29 of 'che ca~hode dis3c and lthe surrounding c:yl1ndrical anode sur-30 1~/ .
3'11 //~ ` ' , ,32 1 /// , , ~ , , ¦ ~ 3 ~ ~
l ; ! : ~ ~ l ~ ' '; . ' ,' ` : ' . .
i7 face near the disc. Because the field is relatively narrow in the direction of gas flow, a high intensity fieLd is achievable without prohibitive electrical power require-ments. The combination of high gas stream velocity through the venturi and the high intensity transverse electric field through which the gas stream passes produces intense ioniza-tion and very high levels of charge on the particles and results in increased collection efficiency notwithstanding the high resistivity of the particulate as in the case of fly ash from low sulfur coal.
One of the problems which has been encountered in connection with co-axial high intensity ionizers of the type described above results from the detrimental ~uild-up of charged particles on the cylindrical anode waIl near the corona discharge plane. Deposition of high resistivity particulate matter in this region results in the phenomena of back corona and excessive sparking with a resulting deterioration in the applied electric field and attendant degradation in particle charging efficiency~ Prior attempts to o~ercome this problem have involved "cleaning" the anode surface in the affected region to eliminate disturbances in the corona due to contaminant build-up on the outer elect-rode. One form of anode cleaning involves the injection of clean gas into the venturi in the corona discharge region to form a protective barrier between the anode wall and the charged particles 1n the gas stream. One particularl~
effect1ve clean gas injection system is described in U.S.
patent 4,108,615 issued August 22, 1978.
According to the present invention, anode cleaning requirements referred to above are reduced by substantially ?~ ~
~ .
,, , -: .,~' ',. .,', .':', ~' : ~ . ,. :, . .
. , ,: . . .
narrowing the width of the current flux band in the annular region between the cathode and anode.
More specifically the invention is a high-in-: tensity gas ionizer comprising: a venturi through which particulate laden gas may flow; a single discharge electrode mounted within the throat of the venturi and having a peri-pheral edge defining a maximum dimension transverse to -the direction of the gas flow; voltage means interconnecte~
between the discharge electrode and the venturi to establish a high-intensity electric field within the ~enturi across the gas flow, the peripheral edge of the discharge electrode having at least one profile-of sufficient curvature that the electric field establishes a corona current in a region between the discharge electrode and the venturi; and first and second cylindrical focusing electrodes mounted along the direction of the gas flow within the venturi, extending coaxially in the first and second directions away from the discharge electrode, being electrically coupled to the discharge electrode and maintained at approximately the same electrical potential as the discharge electrode, having respective diameters less than the maximum transverse dimension of the discharge electrode, and being sized so that corona discharge from the focusing electrodes is substantially non-existent; the first and second focusing electrodes being sized to increase the electric field strength at the fringes of the region of corona current to ~axially limit the region of corona current and thus reduce the surface area of the venturi subjected to collection of particulates in the gas.
;.'~. ' ` ~:
.
.
Desirably the discharge electrode comprises a cathode disc having an arcuate periphery and being co-axially mounted within said venturi and wherein said fo-cusing electrodes comprise cylindrical members on either side of said disc and co-axial therewith. The focusing electrodes on either side of the cathode disc create higher electric fields at the fringes of the current flux band upstream and downstream of the ionizer discharge plane and thus narrow the width of the current flux band in the above annular region. The higher electric fields drive the ions to the anode with higher velocity with a consequent reduc-tion of ion migration upstream and downstream by a mutual repulsion. The net effect is that the width of the band on the anode surface which is subject to particle deposition is reduc~d substantially along with cleaning gas requirements.
The focusing electrodes are sized to provide a high electric field near the anode surface at the fringes of the current flux band by extending circular electrodes on either side o~ the cathode disc a distance approximately equal to the inter-electrode gap between the cathode per-iphery and surrounding anode wall. The downstream focusing electrode cylinder can be terminated beyond that distance by a hemispherical cap. The diameter of the focusing electrode cylinders is preferably between 20% and 40% of the anode inside diameter but not larger than the cathode diameter.
In a further aspect the invention is a method of narrowing the current flux band in a coaxial electrode -5a-~... .
high-intensity gas ionizer including a central cathode element surrounded by a cylindrical anode surface comprising \ the step of generating an increased electrical field having ~ ~ a strength less than the strength required to initiate `~ 5 corona discharge, in a region on both sides of the cathode element extending coaxially away from the cathode element by a distance at least equal to the distance between the cathode element periphery and the cylindrical anode surface, to increase the velocity of ions travelling toward the anode surface~ thereby reducing the amount of ion migration in an axial direction.
The invention is illustrated, by way of example, in the drawings, in which:
Figure 1 is a schematic side elevational view ; 15 illustrating a multi-stage electrostatic precipitator incorporating a high-intensity ionizer according to the present invention;
Figure 2 is an enlarged side view of one ionizer : stage of the apparatus of Figure 1 partially broken away to show the ionizer array;
~ Figure 3 is an end elevational view of the ionizer stage of Figure 2 with the inlet partially broken away to show the ionizer array; .
Figure 4, on the first page of the drawings, is an enlarged partial sectional view of a single ionizer venturi illustrating the electrode arrangement.
' , -5b-.
i7 Turning now to the drawings, Figure 1 shows in schematic side elevational view an electrostatic preci-pitator system incorporating the invention. As seen in this Figure, the precipitator system includes a gas inlet 11 into which gases to be cleaned are directed as sugyested by arrow 12, a gas outlet 13 from which cleaned gases are supplied to appropriate downstream apparatus, e.g. an atmospheric discharge duct, as suggested by arrow 14, and typically a cascaded pair of ionizer-precipitator units generally designated by reference numerals 15, 15'. ~ach ionizer-precipitator unit 15, 15' includes an ionizer stage 16 (16') and typically a pair of conventional electrostatic precipi-tators 17, 18 (17', 18'). Each ionizer stage 16, 16' and precipitator stage 17, 17', 18, 18' is provided with a high voltage input connector 19 coupled to a suitable source of high voltage as described more full~ below and a collecting bin portion 20 for collecting particulate matter precipi-tated from the gas as the latter flows through units 15, 15'.
In operation, gases containing particulate matter enter the Figure 1 apparatus via inlet 11 and pass through the first ionizer stage 16 in which the particles in the gas are electrostatically charged. The gas bearing the elec-trostatically charged particles next flows into successive precipitatox stages 17, 18 in each of which the charged particles are deflected out of the flow path of the gas under the influence of an electrical field established across the flow path, the particles being deposited in the bin portions 20 of the precipitator stages 17, 18. The gas exiting from precipitator 18 is passed through ioni~er stage 16', and precipitator stages 17', 18', to provide additional --6~
X
cleaning therefor, and the cleaned gases emerging from precipitator stage 18' are conducted via gas outlet 13 to appropriate downstream apparatus.
Figures 2 and 3 typically illustrate the gas inlet 11 and the first ionizer stage 16 with more detail~ As seen in these Figures, gas inlet 11 comprises a hollow conduit of trapezoidal or other suitable geometric configuration which is coupled at the downstream side to a gas distributor portion 22. Distributor portion 22 is coupled to an entry chamber 23 formed within the housing of ionlzing unit 16 by the side and bottom walls thereof and a vertically arranged bulkhead 24.
Positioned within the ionizer stage 16 in a regular array are a plurality of venturi diffusers 27 and associated central electrode support members 28 each projecting into either end of the associated venturi 27 (shown here up-stream) and substantially coaxially therewith. Each member 28 is coupled to a bus bar network generally designated by reference numeral 29 and consisting of vertically arranged parallel bus bars (three shown here) interconnected at the upper ends thereof by a common bus bar element 31, the element 31 being connected to a single bus bar element 32 extending from the interior of ionizer stage 16 to an exter-nal conventional high voltage connector shroud 33 to which a high voltage is supplied from a suitable power source (not shown) via high voltage connector 34. The downstream end or outlet of each venturi 27 .is coupled to an exit chamber 36 which is in turn coupled to the inlet of electrostatic precipitator stage 17.
Storage bin 20 is provided with a removable door X
40 for purposes of inspection and cleaning, and a vibrator bracket 41 for permitting the use of an optional conven-tional vibxator to assist in settling any particulate matter collecting in bin 20 towards the bottom edge 42 thereof.
Bottom edge 42 is provided with suita~le apertures (not shown) for enabling the particulate matter to be removed ~rom the bin 20 in a conventional manner. Bins 20 o the remaining system elements 16', 17, 17', 18, and 18' are con~igured in a substantially identical manner.
Each venturi element 27 and associated coaxial member 28 generally comprises an electrode pair for generating a high intensity electric field across the path of gas ~low through the ionizer stage 16. For this purpose, an elec-trode (described below) is carried by each member 28 and is coupled to a source of relatively high negative potential, via bus bar network 29 while each venturi conduit 27 is coupled via the framework o~ the structure to ground poten-tial. Thus each venturi 27 serves as an anode and each - member 28 serves as a cathode support.
In operation, with high voltage applied between ` the cathode and anode, particles suspended in any gas flowing through the ioinzer stage 16 are electrostatically ; charged when passing through the throat of venturi 27. In order to ensure that substantially all charged particles remain suspended in the flowing gas until arriving at the ; downstream precipitator 17 or 18, and do not adhere to the ground potential anode su~face, the novel electrode con~i ;
guration shown in Figure 4 is employed.
With reference to Figure 4, each venturi element 27 is ~ormed with an inwardly tapering conical inlek section -~ :
~, .
X
, '' :, ':
45, a generally cylindrical central section or throat 46 and an outwardly tapering conical outlet portion 47. The cathode includes a conducting disc 50 having a curved peripheral edge which projects outwardly from the outer surface of member 28. Disc 50 is mounted substantially coaxially in the throat of venturi 27 and provides a highly constricted high-intensity electric ~ield in the form of a corona discharge between the curved periphery of disc 50 and the surrounding anode surface 52 when a high poten~ial is applied.
Mounted on either side of cathode disc 50 are focusing electrodes 53 and 54. These electrodes are pre-ferably of cylindrical cross-section and are co-axial with cathode disc 50. Electrodes 53 and 54 are mounted to be in electrical contact with cathode disc 50 and thus are at cathode potential. Upstream focusing electrode 53 may be formed by appropriately sizing electrode support member 28 and maintaining electrical continuity between cathode disc 50, member 28, and bus bar 29. In this case, the downstream end of support member 28 functions as the upstream focusing electrode 53. Downstream focusing electrode 54 may be formed as an extension of support member 28 which extends a sufficient distance downstream of cathode disc 50 and is preferably terminated by a hemispherically shaped end 25 surface 54a. Electrode 54 may be attached to electrode 53 by a threaded stud projecting Erom electrode 54 and passing through the center of cathode disc 50 into support member 28.
Focusing electrodes 53 and 54 increase the strength of the electric field at the fringes of the discharge current _9_ , Z~i7 flux band (indicated at 56) upstream and downstream of the ionizer discharge plane. The increased electrical field in these areas drives the ions to the anode with higher velocity.
Therefore, the ions migrate less upstream and downstream in their expansion by mutual replusion. The net effect is that the width of the current flux band impinging on the anode surface is reduced substantially and the amount of anode surface which must be cleaned is similarly reduced. This in turn reduces cleaning gas requirements and results in an overall increase in particulate collection efficiency.
Focusing electrodes 53 and 54 extend upstream and downstream from cathode disc 50 a distance approximately equal to the inter-electrode separation between tha periphery of cathode disc 50 and the surrounding anode wall. For purposes of the invention, the focusing electrode cylinders can be terminated beyond tha~ distance if desired such as by hemispherically capping the downstream cylinder 54 as described above to prevent corona leakage there, however, extension of the electrode beyond that distance will still provide satisfactory results as indicated by the fact that the physical structure of eIectrode 53 is formed in the depicted embodiment by cathode support element 28 which extends out of the inlet side of venturi 27 terminating at bus bar 2g.
The diameter of the focusing electrode cylinders is preferably between 0.2 and 0.~ of the inside diameter of the anode surface surrounding cathode disc 50. If the diameter is larger or smaller the electric field at the focusing electrode surface is increased promoting surface corona leakage. Eowever, even outside the preferred range, focusing electrodes of the present invention provide improve---10-- ., Z~i~i7 d performance as compared with prior art devices not employ-ing such electrodes.
While a pre~erred embodiment of the present invention has been shown and described above, it will be readily apparent to those skilled in the art that numerous modifications and adaptations thereof may be made without departing from the spirit and scope of the invention as defined by the following claims.
.
Claims (17)
1. A high-intensity gas ionizer for an electro-static precipitator comprising:
venturi means for connecting a source of par-ticulate laden gases with the electrostatic precipitator wherein a gas flow occurs through the venturi means;
a discharge electrode mounted within the throat of the venturi means and having a peripheral edge defining a maximum dimension transverse to the direction of the gas flow;
voltage means interconnected between the discharge electrode and the venturi means to establish a high-in-tensity electric field within the venturi means across the gas flow, the peripheral edge of the discharge electrode having at least one profile of sufficient curvature that the electric field establishes a corona current in a region between the discharge electrode and the venturi means; and first and second cylindrical focusing electrodes mounted along the direction of the gas flow within the venturi means, extending coaxially in the first and second directions away from the discharge electrode, being electri-cally coupled to the discharge electrode and maintained at approximately the same electrical potential as the discharge electrode, having respective diameters less than the maximum transverse dimension of the discharge electrode, and being sized so that corona discharge from the focusing electrodes is substantially non-existent; the first and second focusing electrodes being sized to increase the electric field strength at the fringes of the region of corona current to axially limit the region of corona current and thus reduce the surface area of said venturi means subjected to collec-ting of particulates in the gases.
venturi means for connecting a source of par-ticulate laden gases with the electrostatic precipitator wherein a gas flow occurs through the venturi means;
a discharge electrode mounted within the throat of the venturi means and having a peripheral edge defining a maximum dimension transverse to the direction of the gas flow;
voltage means interconnected between the discharge electrode and the venturi means to establish a high-in-tensity electric field within the venturi means across the gas flow, the peripheral edge of the discharge electrode having at least one profile of sufficient curvature that the electric field establishes a corona current in a region between the discharge electrode and the venturi means; and first and second cylindrical focusing electrodes mounted along the direction of the gas flow within the venturi means, extending coaxially in the first and second directions away from the discharge electrode, being electri-cally coupled to the discharge electrode and maintained at approximately the same electrical potential as the discharge electrode, having respective diameters less than the maximum transverse dimension of the discharge electrode, and being sized so that corona discharge from the focusing electrodes is substantially non-existent; the first and second focusing electrodes being sized to increase the electric field strength at the fringes of the region of corona current to axially limit the region of corona current and thus reduce the surface area of said venturi means subjected to collec-ting of particulates in the gases.
2. The invention of claim 1 wherein the dis-charge electrode comprises a disc, wherein the first focus-ing electrode extends upstream from the discharge electrode disc beyond the venturi means, and wherein the second focusing electrode extends downstream from the discharge electrode disc and terminates in a hemispherical cap.
3. The invention of claim 2 wherein the diameters of the first and second focusing electrodes are equal, and are between 0.2 and 0.4 of the inside diameter of the surface of the venturi means surrounding the discharge electrode.
4. The invention of claim 3 wherein the focusing electrodes extend from either side of the discharge electro-de disc a distance at least equal to the distance between the disc periphery and the surrounding surface of the venturi means.
5. The invention of claim 4 wherein the voltage means maintains the discharge electrode at a negative potential relative to the venturi means.
6. A high-intensity gas ionizer for an electro-static precipitator comprising:
venturi means for establishing a flow of par-ticulate laden gas into the electrostatic precipitator;
a discharge electrode disc mounted coaxially within the throat of the venturi means and having an arcuate periphery defining a disc diameter;
voltage means interconnected between the discharge electrode disc and the venturi means to establish a high-intensity electric field therebetween across the path of the particulate laden gases, the discharge electrode disc having a profile of sufficient curvature such that the electric field establishes a corona current in a region between the arcuate periphery and the venturi means; and first and second cylindrical focusing electrodes mounted coaxially within the venturi means, extending coaxially in the first and second directions away from the discharge electrode disc, being electrically coupled to the discharge electrode disc and maintained at approximately the same electrical potential as the discharge electrode disc;
first and second cylindrical focusing electrodes having respective diameters that are less than the disc diameter, and being sized so that corona discharge from the cylindrical focusing electrodes is substantially non-exis-tent;
the first cylindrical focusing electrode extending upstream from the discharge electrode disc a distance at least equal to the distance between the disc periphery and the venturi means;
the second cylindrical focusing electrode ex-tending downstream from the discharge electrode disc a distance at least equal to the distance between the disc periphery and the surrounding surface of the venturi means and terminating un a hemispherical cap;
such that the first and second cylindrical fo-cusing electrodes increase the electric field strength at the fringes of the region of the corona current, whereby the inside surface area of the venturi means that is subjected to collection of the particulates in the gases is reduced.
venturi means for establishing a flow of par-ticulate laden gas into the electrostatic precipitator;
a discharge electrode disc mounted coaxially within the throat of the venturi means and having an arcuate periphery defining a disc diameter;
voltage means interconnected between the discharge electrode disc and the venturi means to establish a high-intensity electric field therebetween across the path of the particulate laden gases, the discharge electrode disc having a profile of sufficient curvature such that the electric field establishes a corona current in a region between the arcuate periphery and the venturi means; and first and second cylindrical focusing electrodes mounted coaxially within the venturi means, extending coaxially in the first and second directions away from the discharge electrode disc, being electrically coupled to the discharge electrode disc and maintained at approximately the same electrical potential as the discharge electrode disc;
first and second cylindrical focusing electrodes having respective diameters that are less than the disc diameter, and being sized so that corona discharge from the cylindrical focusing electrodes is substantially non-exis-tent;
the first cylindrical focusing electrode extending upstream from the discharge electrode disc a distance at least equal to the distance between the disc periphery and the venturi means;
the second cylindrical focusing electrode ex-tending downstream from the discharge electrode disc a distance at least equal to the distance between the disc periphery and the surrounding surface of the venturi means and terminating un a hemispherical cap;
such that the first and second cylindrical fo-cusing electrodes increase the electric field strength at the fringes of the region of the corona current, whereby the inside surface area of the venturi means that is subjected to collection of the particulates in the gases is reduced.
7. The invention of claim 6 wherein the diameters of the first and second focusing electrodes are equal and between 0.2 and 0.4 of the inside diameter of the surface of the venturi means surrounding the discharge electrode disc.
8. The invention of claim 6 wherein the first cylindrical focusing electrode extends beyond the venturi means.
9. The invention of claim 6 wherein the voltage means maintains the discharge electrode disc at a negative potential relative to the venturi means.
10. A high-intensity gas ionizer comprising:
a venturi through which particulate laden gas may flow;
a single discharge electrode mounted within the throat of the venturi and having a peripheral edge defining a maximum dimension transverse to the direction of the gas flow;
voltage means interconnected between the discharge electrode and the venturi to establish a high-intensity electric field within the venturi across the gas flow, the peripheral edge of the discharge electrode having at least one profile of sufficient curvature that the electric field establishes a corona current in a region between the dis-charge electrode and the venturi; and first and second cylindrical focusing electrodes mounted along the direction of the gas flow within the venturi, extending coaxially in first and second directions away from the discharge electrode, being electrically coupled to the discharge electrode and maintained at appro-ximately the same electrical potential as the discharge electrode, having respective diameters less than the maximum transverse dimension of the discharge electrode, and being sized so that corona discharge from the focusing electrodes is substantially non-existent; the first and second focusing electrodes being sized to increase the electric field strength at the fringes of the region of corona current to axially limit the region of corona current and thus reduce the surface area of the venturi subjected to collection of particulates in the gas.
a venturi through which particulate laden gas may flow;
a single discharge electrode mounted within the throat of the venturi and having a peripheral edge defining a maximum dimension transverse to the direction of the gas flow;
voltage means interconnected between the discharge electrode and the venturi to establish a high-intensity electric field within the venturi across the gas flow, the peripheral edge of the discharge electrode having at least one profile of sufficient curvature that the electric field establishes a corona current in a region between the dis-charge electrode and the venturi; and first and second cylindrical focusing electrodes mounted along the direction of the gas flow within the venturi, extending coaxially in first and second directions away from the discharge electrode, being electrically coupled to the discharge electrode and maintained at appro-ximately the same electrical potential as the discharge electrode, having respective diameters less than the maximum transverse dimension of the discharge electrode, and being sized so that corona discharge from the focusing electrodes is substantially non-existent; the first and second focusing electrodes being sized to increase the electric field strength at the fringes of the region of corona current to axially limit the region of corona current and thus reduce the surface area of the venturi subjected to collection of particulates in the gas.
11. The invention of claim 10 wherein the dis-charge electrode comprises a disc, wherein the first focus-ing electrode extends upstream from the discharge electrode disc beyond the venturi, and wherein the second focusing electrode extends downstream from the discharge electrode disc and terminates in a hemispherical cap.
12. The invention of claim 11 wherein the dia-meters of the first and second focusing electrodes are equal, and are between 0.2 and 0.4 of the inside diameter of the surface of the venturi surrounding the discharge electrode.
13. The invention of claim 12 wherein the focusing electrodes extend from either side of the discharge electrode disc a distance at least equal to the distance between the disc periphery and the surrounding surface of the venturi.
14. The invention of claim 10 wherein the venturi is one of a plurality of venturis arranged in an array with their axes aligned and their inlets in fluid communication with one another, each of the venturis having associated therewith a single discharge electrode and first and second focusing electrodes.
15. A method for narrowing the current flux band in a coaxial electrode high-intensity gas ionizer including a central cathode element surrounded by a cylindrical anode surface comprising the step of:
generating an increased electrical field having a strength less than the strength required to initiate corona discharge, in a region on both sides of the cathode element extending coaxially away from the cathode element by a distance at least equal to the distance between the cathode element periphery and the cylindrical anode surface, to increase the velocity of ions travelling toward the anode surface, thereby reducing the amount of ion migration in an axial direction.
generating an increased electrical field having a strength less than the strength required to initiate corona discharge, in a region on both sides of the cathode element extending coaxially away from the cathode element by a distance at least equal to the distance between the cathode element periphery and the cylindrical anode surface, to increase the velocity of ions travelling toward the anode surface, thereby reducing the amount of ion migration in an axial direction.
16. The method of claim 15 wherein the step of generating an increased electrical field includes the substeps of: providing first and second cylindrical focusing electrodes of a diameter less than that of the central cathode element and of a diameter that avoids surface corona leakage, the focusing electrodes extending coaxially away from each side of the cathode element; and applying an electrical potential to the focusing electrodes that is approximately the same as the electrical potential on the discharge electrode.
17. A method of narrowing the current flux band in a coaxial electrode high-intensity gas ionizer including a central discharge electrode disc surrounded by a cylin-drical venturi surface comprising the steps of:
providing first and second cylindrical focusing electrodes extending coaxially in first and second direc-tions away from the discharge electrode disc a distance at least equal to the distance between the disc periphery and the venturi surface, the focusing electrodes having a diameter less than that of the discharge electrode disc and further sized to avoid corona discharge from the focusing electrodes; and applying an electrical potential to the focusing electrodes that is approximately the same as the electrical potential on the discharge electrode disc; to thus generate an increased electric field in a region on either side of the discharge electrode disc, which field has a maximum strength that is below the field strength required to initiate a corona discharge, the field increasing the velocity of ions travelling toward the venturi surface, thereby reducing the amount of ion migration in an axial direction.
providing first and second cylindrical focusing electrodes extending coaxially in first and second direc-tions away from the discharge electrode disc a distance at least equal to the distance between the disc periphery and the venturi surface, the focusing electrodes having a diameter less than that of the discharge electrode disc and further sized to avoid corona discharge from the focusing electrodes; and applying an electrical potential to the focusing electrodes that is approximately the same as the electrical potential on the discharge electrode disc; to thus generate an increased electric field in a region on either side of the discharge electrode disc, which field has a maximum strength that is below the field strength required to initiate a corona discharge, the field increasing the velocity of ions travelling toward the venturi surface, thereby reducing the amount of ion migration in an axial direction.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US78547077A | 1977-04-07 | 1977-04-07 | |
| US785,470 | 1977-04-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1102257A true CA1102257A (en) | 1981-06-02 |
Family
ID=25135607
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA286,553A Expired CA1102257A (en) | 1977-04-07 | 1977-09-12 | Focusing electrodes for high-intensity ionizer stage of electrostatic precipitator |
Country Status (10)
| Country | Link |
|---|---|
| JP (1) | JPS53125675A (en) |
| AU (1) | AU511788B2 (en) |
| CA (1) | CA1102257A (en) |
| CH (1) | CH621492A5 (en) |
| DE (1) | DE2744557A1 (en) |
| FR (1) | FR2386353A1 (en) |
| GB (1) | GB1591826A (en) |
| IT (1) | IT1090921B (en) |
| SE (1) | SE7712050L (en) |
| SU (1) | SU820647A3 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108128854B (en) * | 2018-01-18 | 2023-07-18 | 昆明理工大学 | Method and device for recycling saline water based on corona discharge coupling electrodialysis |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1488717A (en) * | 1966-08-04 | 1967-07-13 | Gourdine Systems Inc | Method and device for precipitating particles, and their applications |
| FR2341215A1 (en) * | 1976-02-16 | 1977-09-09 | Air Pollution Syst | Electrostatic solid particle charging and gas flow ionisation - has twin cylindrical electrodes between which electrostatic field and gas flow pass |
| FR2365901A2 (en) * | 1976-02-16 | 1978-04-21 | Air Pollution Syst | High intensity ionising dust precipitator - has discharge electrode fitted concentrically inside duct-shaped outer electrode through which dust laden gas flows (NL 29.3.78) |
-
1977
- 1977-09-12 CA CA286,553A patent/CA1102257A/en not_active Expired
- 1977-09-28 AU AU29195/77A patent/AU511788B2/en not_active Expired
- 1977-09-29 JP JP11727677A patent/JPS53125675A/en active Pending
- 1977-10-04 DE DE19772744557 patent/DE2744557A1/en not_active Withdrawn
- 1977-10-12 CH CH1246377A patent/CH621492A5/en not_active IP Right Cessation
- 1977-10-25 GB GB4427677A patent/GB1591826A/en not_active Expired
- 1977-10-26 SE SE7712050A patent/SE7712050L/en not_active Application Discontinuation
- 1977-11-07 IT IT5171477A patent/IT1090921B/en active
-
1978
- 1978-01-26 FR FR7802183A patent/FR2386353A1/en active Granted
- 1978-01-31 SU SU782571847A patent/SU820647A3/en active
Also Published As
| Publication number | Publication date |
|---|---|
| SE7712050L (en) | 1978-10-08 |
| DE2744557A1 (en) | 1978-10-12 |
| GB1591826A (en) | 1981-06-24 |
| SU820647A3 (en) | 1981-04-07 |
| AU2919577A (en) | 1979-04-05 |
| FR2386353B1 (en) | 1982-03-12 |
| CH621492A5 (en) | 1981-02-13 |
| JPS53125675A (en) | 1978-11-02 |
| IT1090921B (en) | 1985-06-26 |
| FR2386353A1 (en) | 1978-11-03 |
| AU511788B2 (en) | 1980-09-04 |
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