CA1076488A - Electrode means for wet wall electrostatic precipitators - Google Patents
Electrode means for wet wall electrostatic precipitatorsInfo
- Publication number
- CA1076488A CA1076488A CA246,817A CA246817A CA1076488A CA 1076488 A CA1076488 A CA 1076488A CA 246817 A CA246817 A CA 246817A CA 1076488 A CA1076488 A CA 1076488A
- Authority
- CA
- Canada
- Prior art keywords
- discharge
- screen
- bars
- discharge electrode
- 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
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
- B03C3/45—Collecting-electrodes
- B03C3/49—Collecting-electrodes tubular
-
- 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
- B03C3/16—Plant or installations having external electricity supply wet type
-
- 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)
Abstract
ABSTRACT OF THE DISCLOSURE
The disclosure relates to an electrode means for wet wall electrostatic precipitators wherein a generally cylindrical annular in cross section screen like discharge electrode is disposed concentrically between concentric spaced apart wet wall collector electrodes. The disclosure also relating to specific details of the screen like structure of the discharge electrode means and also specifically to the material of which the discharge electrode is made comprising stainless steel but preferably Titanium. Further the disclosure relates to specific details of the screen like structure of the discharge electrode which comprises points formed by clipping bars of the screen like structure to form projecting stubs which have ends and which ends form discharge points for the electrode means. Further the disclosure relates to a suspension means for the cylindrical discharge electrode in relation to the aforementioned concentric spaced apart wet wall collector electrodes between which the dis-charge electrode is positioned.
The disclosure relates to an electrode means for wet wall electrostatic precipitators wherein a generally cylindrical annular in cross section screen like discharge electrode is disposed concentrically between concentric spaced apart wet wall collector electrodes. The disclosure also relating to specific details of the screen like structure of the discharge electrode means and also specifically to the material of which the discharge electrode is made comprising stainless steel but preferably Titanium. Further the disclosure relates to specific details of the screen like structure of the discharge electrode which comprises points formed by clipping bars of the screen like structure to form projecting stubs which have ends and which ends form discharge points for the electrode means. Further the disclosure relates to a suspension means for the cylindrical discharge electrode in relation to the aforementioned concentric spaced apart wet wall collector electrodes between which the dis-charge electrode is positioned.
Description
PR [()R l~RT
~n e~ample o~ some o~ the patent6 in tne prlor art are the foLlowing Unlted States patents:
~n e~ample o~ some o~ the patent6 in tne prlor art are the foLlowing Unlted States patents:
2,937,709
3,053,029 3,7~2,681 3,785,125 3,856,476 BACKGROUND OF THE INVENTION
The aforementioned prior art patents disclose generally annular in cross section concentrically spaced wet wall collector electrodes with discharge electrodes disposed between the spaced apart wet wall electrodes. The discharge electrodes of the .' :~!
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; prior art have generally been composed of arrays of rods vertically suspended between the adJacent wet walls of the collector elec-trodes and many of these discharge electrode rodæ have been generally circular in cross section and generally axially parallel to the annular in cross section cylindrical structures of the wet wall collector electrodes.~ With such discharge electrode structure of the prior art, it has been difficult to obtain the desired corona field density in various areas of the passages between the collector walls and around the discharge electrodes.
With a group of suspended discharge electrode rods, it has been difficult to vary the corona field density as for example, the density of the corona field from one end of the rods to the opposite end thereof such as may be desirable in relation to the flow direction of particle laden air or gases which have hereto-` fore been directed around such rods in areas between wet wall surfaces of collector electrodes. Additionally, the inætallation and maintenance of large arrays of individually suspended rods ./ has been costly in installation and maintenance labor.
Furthermore, the aerodynamics related to the flow of gases longitudinally of rod like discharge electrodes has not ;~; ;
provided an optimum correlation between electrostatic charging - of particles and mechanical direction of particles in the gas by means of aerodynamically functional features of the discharge ' ~-electrode structures bf the prior art.
SUMMARY OF THE INVENTION
The invention relates to an electrode means for wet wall electrostatic precipitators including a discharge electrode and also its relationship to wet wall collector electrodes; more particularly the invention relates to a screen like or foraminous i 30 structure of the discharge electrode means of either annular in .' : .:
' cross section cylindrical form or flat configuration. The invention specifically relates to a screen like or foraminous " ;'~,~ ' - 2 - ~ ;
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1~76~8 structure oE the discharge electrode means wherein either screen or perforate structures are provided with point structures extending outward to provide points of electrical discharge for creating the well known corona effect Eor ionically charging particles of material passing between the electrodes so as to cause the particles to be attracted to the wet wall surfaces of collector electrodes. The preferred structure of the discharge electrode means of the invention comprises a hollow cylindrical annular in cross section electrode structure having screen like or foraminous wall means provided with discharge points extending from opposite sides thereof. The discharge electrode is pre-ferably made of Titanium although it may be made of stainless steel or the like. However, Titanium has been discovered to be considerably more durable in an electrostatic precipitator handling corrosive gases.
In the screen like structure of the discharge electrode of the invention, screen like material such as expanded metal ' has been found to perform extremely well and have substantial rigidity so as to maintain accurate spacing thereof relative to wet wall surfaces of adjacent collector electrodes.
Additionally, the screen like structure of expanded metal has been found to have particularly good performance characteristics in that the bars of the screen like structure are generally rectangular in cross section and are formed by shearing processes which leave very sharp corners forming points ~ for electrical discharge to provide for the well known corona ; effect.
Additionally, the generally diamond shaped mesh of the expanded metal comprises integral interconnecting bars, some of which are sheared to provide terminal ends of the bars ~ and each terminal end being substantially rectangularin cross sec-., :
,. .
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1~)764~8 tion and having four sharpcorners, all of which provide points for the emissions of electrical charges to provide for the desired corona effect. The clipping of the bars may be varied so as to provide more or less of the terminal ends of the bars to there-by predetermine the concentration of points and the related corona field density provided by discharge from these points.
The general cross section of the screen like means provided by expanded metal is undulating and has a substantial ~ .
section modulus quite greater than the sheet from which the expanded metal is formed. This extended section or structure when wrapped into a circular in cross section cylinder provides a very rigid cylinder and one which may be accurately spaced relative to adjacent collector electrode walls. It will be under-stood that the disposition of the expanded metal in a hollow cylindrical circular in cross section form~ due to the curvature thereof, provides a very rigid structure with a nominal amount -~
of material and weight.
The foregoing cylindrical structure is suspended from -suspension arms and hangs generally vertical with the central axis of the circular in cross section structure in a substantially vertical position with related hollow cylindrical collector electrodes in the same disposition and concentrically spaced relative thereto such that the discharge electrode i5 disposed between a pair of concentric wet wall surfaces of the collector electrodes. The specific structure of the discharge electrode `
hauing screen like or foraminous structure employs a circular frame element near the lower portion and another circular frame element near the upper portion to which suspension rods are attached and which are supported on candelabra arms above the -~
discharge and collector electrodes of the invention.
The use of the discharge electrode means having points
The aforementioned prior art patents disclose generally annular in cross section concentrically spaced wet wall collector electrodes with discharge electrodes disposed between the spaced apart wet wall electrodes. The discharge electrodes of the .' :~!
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.
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: . . : . ` ` . , : . , `, . : : . ....
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:: . , , : . . : ` . : ` :
~`'', ' ` '`,' ' , ~ ` ' ' , , ':
. ~,' '" , . , ' ' . '' 1~7f~
; prior art have generally been composed of arrays of rods vertically suspended between the adJacent wet walls of the collector elec-trodes and many of these discharge electrode rodæ have been generally circular in cross section and generally axially parallel to the annular in cross section cylindrical structures of the wet wall collector electrodes.~ With such discharge electrode structure of the prior art, it has been difficult to obtain the desired corona field density in various areas of the passages between the collector walls and around the discharge electrodes.
With a group of suspended discharge electrode rods, it has been difficult to vary the corona field density as for example, the density of the corona field from one end of the rods to the opposite end thereof such as may be desirable in relation to the flow direction of particle laden air or gases which have hereto-` fore been directed around such rods in areas between wet wall surfaces of collector electrodes. Additionally, the inætallation and maintenance of large arrays of individually suspended rods ./ has been costly in installation and maintenance labor.
Furthermore, the aerodynamics related to the flow of gases longitudinally of rod like discharge electrodes has not ;~; ;
provided an optimum correlation between electrostatic charging - of particles and mechanical direction of particles in the gas by means of aerodynamically functional features of the discharge ' ~-electrode structures bf the prior art.
SUMMARY OF THE INVENTION
The invention relates to an electrode means for wet wall electrostatic precipitators including a discharge electrode and also its relationship to wet wall collector electrodes; more particularly the invention relates to a screen like or foraminous i 30 structure of the discharge electrode means of either annular in .' : .:
' cross section cylindrical form or flat configuration. The invention specifically relates to a screen like or foraminous " ;'~,~ ' - 2 - ~ ;
': :
i. , . , ... . :, . . :
. ': . , , . ~ , . ~ , .
1~76~8 structure oE the discharge electrode means wherein either screen or perforate structures are provided with point structures extending outward to provide points of electrical discharge for creating the well known corona effect Eor ionically charging particles of material passing between the electrodes so as to cause the particles to be attracted to the wet wall surfaces of collector electrodes. The preferred structure of the discharge electrode means of the invention comprises a hollow cylindrical annular in cross section electrode structure having screen like or foraminous wall means provided with discharge points extending from opposite sides thereof. The discharge electrode is pre-ferably made of Titanium although it may be made of stainless steel or the like. However, Titanium has been discovered to be considerably more durable in an electrostatic precipitator handling corrosive gases.
In the screen like structure of the discharge electrode of the invention, screen like material such as expanded metal ' has been found to perform extremely well and have substantial rigidity so as to maintain accurate spacing thereof relative to wet wall surfaces of adjacent collector electrodes.
Additionally, the screen like structure of expanded metal has been found to have particularly good performance characteristics in that the bars of the screen like structure are generally rectangular in cross section and are formed by shearing processes which leave very sharp corners forming points ~ for electrical discharge to provide for the well known corona ; effect.
Additionally, the generally diamond shaped mesh of the expanded metal comprises integral interconnecting bars, some of which are sheared to provide terminal ends of the bars ~ and each terminal end being substantially rectangularin cross sec-., :
,. .
. '~: . .
1~)764~8 tion and having four sharpcorners, all of which provide points for the emissions of electrical charges to provide for the desired corona effect. The clipping of the bars may be varied so as to provide more or less of the terminal ends of the bars to there-by predetermine the concentration of points and the related corona field density provided by discharge from these points.
The general cross section of the screen like means provided by expanded metal is undulating and has a substantial ~ .
section modulus quite greater than the sheet from which the expanded metal is formed. This extended section or structure when wrapped into a circular in cross section cylinder provides a very rigid cylinder and one which may be accurately spaced relative to adjacent collector electrode walls. It will be under-stood that the disposition of the expanded metal in a hollow cylindrical circular in cross section form~ due to the curvature thereof, provides a very rigid structure with a nominal amount -~
of material and weight.
The foregoing cylindrical structure is suspended from -suspension arms and hangs generally vertical with the central axis of the circular in cross section structure in a substantially vertical position with related hollow cylindrical collector electrodes in the same disposition and concentrically spaced relative thereto such that the discharge electrode i5 disposed between a pair of concentric wet wall surfaces of the collector electrodes. The specific structure of the discharge electrode `
hauing screen like or foraminous structure employs a circular frame element near the lower portion and another circular frame element near the upper portion to which suspension rods are attached and which are supported on candelabra arms above the -~
discharge and collector electrodes of the invention.
The use of the discharge electrode means having points
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lQ76~88 .:
on opposite sides is such that the concentration of these points may be varied in such a manner that the electrical discharge from the discharge electrode may afford a very high corona field density near the inlet of passages between the collector electrodes wherein air laden with foreign matter flows and is ionically charged so as to be driven or attracted to the wet wall surfaces of the collector electrodes.
The discharge electrode means of the invention also provides an aerodynamic effect which causes angular departure 10 of the fluids flowing adjacent to the discharge electrodes. such that the angular departure is directed toward the collector electrodes and thus the aerodynamic effect provided by the dis-charge electrode means of the invention assists the ionic function of the corona field to force the particles carried by : the air flow adjacent the electrodes into contact with the collector electrodes.
1 Further, the invention comprises a discharge electrode ~' means which is either screen like or foraminous so that the :~
aerodynamic function around the electrodes is e~ualized from a :
pressure standpoint to alleviate the possibility of creating a pressure differential at opposite sides of the discharge electrode ~
.i and to thereby change the flow characteristics adjacent to respect-ive collector electrodes at opposite sides of the discharge elect~
rode.
Accordingly, it will be appreciated that the perforate or screen like structure allows an even pressure or flow distri-bution to exist at opposite sides of the discharge electrode and to thereby permit substantially laminar flow of fluids adjacent ~
to the collector electrodes. `
~ 30 Accordingly, it is an object of the present invention to provide a novel screen like or foraminous discharge elec-trode .
' . . . .
'':~ ' ' ' ' , , , ' ' ' ' 1076~L88 means for cooperative functlon with wet wall collector electrodes of an electrostatic preclpitator.
Another object of the invention is to provide a novel screen like or foraminous dlscharge electrode having discharge points on opposite sides thereof which may be varied in concentra~
tion to vary the corona field density in a direction from the inlet to the outlet of an electrostatic precipitator in which the discharge electrode is positioned.
Another object of the invention is to provide a novel ~ -discharge electrode for electrostatic precipitators wherein a screen like electrode structure is formed of expanded metal or the like wherein the cross sectional shape of the bars of the screen like expanded metal are sheared and have rectangular cross section provided with sharp edges to provide for discharge points and further to provide such a structure in which some of ;
: the bars are clipped off to provide terminal stub portions which form discharge points, the stub portions having ends rectangular - in cross section with four corners, all of which are sharp and provide ideal electrostatic discharge teFminals.
Another object of the invention is to provide a screen like discharge electrode for electrostatic precipitators wherein a screen such as formed from expanded metal has an extended cross ;~ ;
section in proportion to its weight and is relatively rigid ; , thereby providing for integrity of the structure in its spaced relation with adjacent wet wall surfaces of the collector : electrodes thus maintaining or providing for efficient establish-`, ment of a corona field and minimizing the possibility of having .. , ~ .
. arcing from the discharge electrode to the collector electrodes. ;
Another object of the invention is to provide a novel discharge electrode for electrostatic precipitators which is made of Titanium and which has been found to be very durable and efficient in an electrostatic precipitator environment.
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Thus, and in accordance with the present teachings, a discharge electrode for wet wall electrostatic precipitators is provided. The discharge electrode is of hollow cylindrical shape and has annular in cross section foraminous screen like wall structure provided with upper and lower portions. The screen like wall structure comprises expanded metal which has interconnecting bars substantially rectangular in cross section and has corners forming electrostatic discharge points with some of the bars interconnecting each other at an angle. Ths bars are provided with stubs formed by clipping away portions of some of the bars to leave the stubs which have terminal ends forming electrode discharge points. The wall structure which is annular in cross section has opposite surfaces and a pluralityfor discharge points disposed at the opposite surfaces.
The bars of the screen like structure are all integral with each other and disposed in a group of parallelograms, each parallelogram having a pair of parallel bars constituting long sides of a respective parallelogram and also a pair of spaced apart parallel bars constituting short sides of each parallelo-gram. The stubs pro~ect at an angle to and in opposite directionsfrom the-intermediate portions of the long side, the stubs being the discharge points, and the discharge points in the lower portion being highly concentrated with the concentration gradually diminishing toward the upper portions.
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Another object o~ the invention is to provide a discharge electrode for electrostatlc precipitators having novel aerodynamic Eunctions which cooperate with the electrostatic functions to mechanically move foreign matter in an alr stream ; in addition to the ionic forces in attaining collection of the foreign particles on the collector electrodes.
Another object of the invention is to provide a dis- ;
charge electrode for electrostatic precipitators which, due to its aerodynamic function, causes foreign particles in an air stream to be aerodynamically projected toward the collector electrodes and while at the same time the discharge electrode ;~
structure does not upset the desired flow or pressure characteris-tics of the fluid at opposite sides thereof and ad~acent to respective wet wall surfaces of collector electrodes.
Another object of the invention is to provide a novel discharge electrode means for electrostatic precipitators ~hich may be directly applicable to either annular in cross section electrode assemblies or to the conventional flat electrode ~ :
assemblies.
` 20 Another object of the invention is to provide a ' variety of structures which may be adapted for use in collector electrodes of electrostatic precipitators and mainly structures , which are either screen like or foraminous with discharge points on opposite sides thereof and sufficient openings or perfora-tions so as to maintain even pressure and flow distribution :- .
at opposite sides of the discharge electrode so as to avoid : upsetting the desired laminar flow characteristics for efficient `;
aerodynamic and ionic collection of particles on the wet wall surfaces of the collector electrodes.
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.: : ' ~076488 Further ob~ects and advantages of the invention may be apparent from the following specification, appended claims and accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a fragmentary top or plan view of an electrode assembly of an electrostatic precipitator showing a discharge electrode means between a pair of collector electrodes and showing suspension means for the discharge electrode means;
Figure 2 is a side elevational view of the structure shown in Fig. 1 and showing portions broken away and in section to amplify the illustration.
Fig. 3 is an enlarged fragmentary sectional view of -~
the discharge electrode means taken from the line 3-3 of Fig. 2;
Fig. 4 is a fragmentary sectional view taken from the line 4-4 of Fig. 3 showing the suspension means for the dlscharge electrode;
Fig. 5 is an enlarged fragmentary view of screen like structure of the discharge electrode as shown in Fig. 4~
Fig. 6 is an enlarged fragmentary sectional view taken from the line 6-6 of Fig. 5 showing a cross section of the screen like electrode structure disclosed in Fig. 5;
Fig. 7 is an enlarged fragmentary view similar to Fige 5 showing a modified form of the discharge electrode screen structure;
Fig. 8 is an enlarged sectional view taken from the line 8-8 of Fig. 7 showing the cross sectional shape of the bars of -the screen like structure shown in Fig. 7;
Fig. 9 i8 an enlarged fragmentary sectional view taken from the line 9-9 of Fig. 7;
Fig. 10 is a fragmentary plan view taken in the same direction as Fig. 1 showing an end of a modified form of the , ~769~88 discharge electrode structure of the inventlon;
Fig. 11 is a view similar to Fig. 6 showing a further modified form oE the discharge electrode structure of the invention;
Fig. 12 is a fragmentary sectional view taken from the line 12-12 of Fig. ll;
Fig. 13 is a fragmentary sectional view taken from the line 13-13 of Fig. 12;
Fig. 14 is a view similar to Fig. 10 showing a further modified form of the discharge electrode structure of the inven-tion; and Fig. 15 is an enlarged fragmentary sectional view taken -~ ~
from the line 15-15 of Fig. 14. ~ -DESCRIPTION OF THE PREFERRED EMBODI~ENTS `
As shown in Figs. 1 and 2 of the drawings, the electrode means for wet wall electrostatic precipitators of the invention comprises a discharge electrode 20 and a pair of collector electrodes 22 and 24. The collector electrodes 22 and 24 are provided with respective wet wall collector surfaces 26 and 28. These surfaces are adapted to operate with a film of liquid flowing downward on them. ~
As shown in Fig. 2 of the drawings, the discharge -electrode 20 is suspended by a plurality of rods 30 which are ;
supported on candelabra arms 32 which are supported in ~uxta- ;
position by means not shown. The discharge electrode 20 is provided with a screen like or foraminous structure 34 having an annular ring like frame member 36 at its upper end to which the suspension rods 30 are secured by welding or other suitable means.
The screen like structure 34 is preferably welded or fused to the ring like frame 36 and this screen like structure 34 g , .. .. ~ ........................................................ .
., ,: , . :
~' ' , ' , 107~8 Of the discharge electrode 20 at its lower end is provided with a ring shaped frame member 38 to which the screen like structure 34 is preferably welded.
As shown in Fig. 4, it will be seen that the suspension rods 30 are provided with externally screw threaded portions 40 on which nuts 42 and 44 are screw threadably disposed. These nuts 42 and 44 are vertically screw threadably adjustable on the screw threaded portion 40 of each of the rods 30 and each screw threaded portion of each rod 30 passes through a respective horizontal member 32 which is preferably tubular in cross section.
The nut 44 on each rod 30 engages an upper side of the respective member 32 and each nut 42 on each suspension rod 30 engages a lower portion of the respective member 32 so that the suspension of the hollow cylindrical discharge electrode may be adjusted in order to attain alignment suspension of the discharge electrode concentrically between the respective wet wall surfaces 26 and 28 of the collector electrodes 22 and 24. The spacing is critical to provide efficient Eormation of a proper corona field and to avoid local and continuous arcing between the dis-charge electrode and the collector electrodes to thereby achieverandom sparking throughout the precipitator. Accordingly, the adjustability of the suspension rods 30 allows the collector electrode to be properly aligned in direct concentric and parallel-- ism with the respective wet wall surfaces 26 and 28 hereinbefore described.
As shown in Fig. 2 of the drawings, the electrode struc-ture when in operation receives air or gases flowing in the dir-ection of the arrows A in Fig. 2 of the drawings upwardly between the wet wall surfaces 26 and 28 and at opposite sides oE the discharge electrode 20, it being seen that the discharge elec-trode 20 and the collector electrodes 22 and 24 are annular in 107~88 cross section concentric structures.
Referring to Fig. 3 of the drawings, it will be seen ~ ~;
that the screen like structure 34 of the discharge electrode 20 comprises generally a diamond shaped arrangement of bars designated 46 which are all integral with each other. The screen like struc- ,, ture 34 as shown in Fig. 3 being an expanded metal structure initi-ally formed and sheared from a flat sheet of metal. Some of the 'i bars 46 are clipped off to form stubs 48 which form electrical . ;. ~, .
discharge points and, as shown in Fig. 3, a substantially greater ~ , , ' number of these discharge points 48 are provided near the lower or inlet end of the discharge electrode so as to provide a high -~
density corona field at the lower inlet end as indicated by the arrows A in Fig. 2 of the drawings. The lower edge of the '~
ring shaped frame member 38 being provided with a plurality of '' ~ ' points 50 similar to those provided by the stubs 48j it being noted that the clipping pattern may be varied in order to provide a greater or lesser number of these discharge points and thus the corona field density may be varied in the direction of flow of particle laden air or gas which passes between the discharge ~;~
electrode 20 and the adjacent wet wall surfaces 26 and 28 of the -collector electrodes 22 and 24.
The screen like structure 34 at the upper and lower ends ,~, thereof is maintained in a substantially accurate rigid annular form by the ring shaped frame members 36 and 38 and these members 36 and 38 as shown in Fig. 4 are preferably tubular members of flattened cross sectional shape.
The suspension rods 30 as well as the frame rings 36 ' ~ -~
and 38 and the screen like structure 34 may all be made of stainless steel or the like, however, Titanium is the preferred material from whlch these parts are to be made inasmuch as Titanium has been found to be very durable and efficient ",,, , , ,, , : , , 1 ~7f~
in an electrostatic precipitator handling corrosive gases.
The screen like structure 34 made of expanded metal such as shown in Fig. 5~ comprises integral, interconnecting parallel-ograms, each having four bars designated 52, 54, 56 and 58, the bars 52 and 54 being relatively short and the bars 56 and 58 being relatively long, the pattern being such that bars similar to the bars 52 and 54 are clipped to provide the stubs 48 also shown in Fig. 3 of the drawings, and these stubs project in opposite directions from intermediate portions of the long bars 56 and 58 of each parallelogram all of which are integral with each other and generally formed of expanded metal.
The cross sectional shape of each of the bars 52, 54, ~
56 and 58 is generally rectangular in cross section as shown in - ~ ; ;
Fig. 6 of the drawings and corresponds to the ends of the points 48 disclosed therein. All of the parallelogram portions of the screen pattern are integral at the areas designated 60, all of which is shown in Figs. 5 and 6 of the drawings. -As shown in Fig. 6 of the drawings, the expanded metal configuration is such that the bars generally designated 46 in Fig. 3 of the drawings are disposed in an undulating relationship such as to provide a substantially more rigid section than would be the case of the sheet of metal had it been left in flat condition. Accordingly, the increased section modulus of the structure as shown in Fig. 6 provides for substantial rigidity of the structure which is a relatively lightweight as-sembly of bars relative to the overall size and area thereof.
This undulating structure shown in Fig. 6 having a substantial section modulus is quite rigid and particularly so when formed into the circular in cross section structures shown in Figs. 1 and 2 and thus affords rigidity compatible with the accuracy of spacing required of the discharge electrode 20 relative to ~ ' ~
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10764~38 :
the adjacent wet wall surfaces 26 and 28 of the collector elec-trodes 22 and 24. ~`
In ~he modification of the screen structure 34 shown in Fig. 7 of the drawings, the expanded metal is arranged in a different clipped pattern to provide the point forming stubs 48.
This pattern comprises a plurality of parallelograms including ~-one generally V-shaped portion 62 and a second V-shaped portion 64. The V-shaped portion 62 having an apex 66 and the V-shaped ;~
portion 64 having an apex portion 68. These apex portions 66 , and 68 being opposed to each other and each of the parallelograms consisting of the V-shaped portions 62 and 64 being integral with each other at areas 70 which correspond with the area 60 ~
as shown in Fig. 5. ~ -The V-shaped portions 62 and 64 are provided with the clip- ~ -ped stubs 48 at areas intermediate the integral portions 70 and ~`
the apex portion 66. Thus the stubs 48 are disposed at inter- ~ ~-mediate portions between the apex portions and the portions 70 which are integral with adjacent parallelograms all generally formed by the hereinbefore mentioned bars 46 of the expanded metal and depending upon the clipping of these bars at particular areas to form the stubs 48 which act as discharge points for the discharge electrode 20 of which the screen like structure 34 is a primary part.
~s shown in Fig. 8 of the drawings, each bar 46 is pro- ~, vided with four corners 72. These corners being sharp due to the fact that the expanded metal is sheared in the initial forming and these corners 72 of the bars 46 are all capable of performing as discharge points. Thus due to the undulating structural ar-rangements as shown in Figs. 6 and 9 of the drawings, the corners of the intersections 60 and 70 all function as discharge points since they are at the lateral extremities of the screen structure .
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... .
1~7641~i18 34. Thus the screen like structure 34 of the discharge electrode 20 when Eormed of expanded metal is capable of providing for a great many electrical discharge points or sharp edgea to provide for a high density corona field and the open mesh of the structure also has aerodynamic functional characteristics which cause the Elow to depart away from the screen like structure 34 at an acute angle approximating an angle in the range of four to five degrees and thus the aerodynamic function causes gas flow and the flow of particulate matter to progress away from the screen like structure and toward the respective wet wall surfaces 26 and 28 of the collector electrodes 22 and 24, This aerodynamic ef- ~ -fect is cooperative with the ionic effect on the particles for forcing them toward the wet wall surfaces 26 and 28 of the collector electrodes 22 and 24.
It will be seen that each of the intersectiona 60 as shown in Fig. 6 is provided with four corner edges 74 which may ;~
serve as discharge points. These points 74 being at the lateral extremities of the screen structure 34 and the intersections 70 shown in Fig. 9 of the drawings are provided with sharp corner ~-edges 76 which are also at the lateral extremities of the screen structure 34 and thus they serve as discharge points for the dis-charge electrode 20.
~ dditionally, it will be seen that similar sections 78 as shown in Fig. 7 of the drawings are disposed between the stubs 48.
These sections 78 are provided with corners 80 similar to the -corners or edges 76 and they also provide substantial discharge points. Likewise portions 82 form intersections between the stubs 48 shown in Fig. 5 of the drawings, and these portions 82 have a similar cross section to the integral portion 60 shown in Fig. 6 and they also have similar corners structurally equiva-lent to the corners 74 which are at the lateral extremities of ,: . . . . . . . . ............... . .
' :' , ,: , ,.'' ~ ' ' :':
.
107~4t~
the screen like structure 34 and thus they also provide discharge point capabilities.
In ~he modification as shown in Fig, 10 of the drawings, a discharge electrode 88 is of annular form but shown ;
fragmentarily and Fig. 10 discloses the discharge elect~ode in the same plane as that shown in Fig. 1. This discharge electrode ;
: .
88 is formed of a sheet of metal having generally triangular taba ;; -~90 punched therefrom and extending in opposite directions at opposite sides oE the plate to form discharge points~ These tabs 90 being similar to the tab structures as will be hereinafter des~
cribed in connection with the disclosure of Fig. 11 and 12 of the drawings.
It will be seen that the plane of these tabs 90 may be at right angles to the direction of flow and the openings from which the tabs are punched out provide for equalization of pressure to maintain proper flow distribution as will be hereinafter des--cribed in connection with the disclosure of Figs. 11 and 12.
As shown in Fig. 11 a sheet of metal designated 92 is provided with a plurality of punched out openings 9~ from which tabs 96 are projected laterally of the plate~ These tabs being shown in Figs. 12 and 13 of the drawings and are generally triangular and disposed in opposite directions from the sheet 92.
The tabs 96 are each provided with an apex point 98 and thus provide discharge points of opposite sides o e the sheet 92.
As shown in Figs. 11 and 12 these tabs 96 are parallel to the axis of flow indicated by the arrow A which corres-pond with the arrows A in Figs. 2 and 3 of the drawings. The structure shown in Fig. 10 of the drawings has the tabs 90 dis-posed at right angles generally to the direction of flow or may have them at an angle to the flow if desired but depending upon certain requirements of electrostatic precipitators having .
' . ' ' ' , , ~ , , ~ ' . ' , . , ... . ~, .
~0769L8~
varying configurations which may be desired. ~, It will be seen that each of the tabs 96 when punched ~;
out of the plate 92 leaves a respective opening 100 and these openings 100 may approximate twenty percent of the overall area of the plate 92 so as to provide for equalization oE preasure and flow characteristics at opposite sides oE a discharge electrode formed of such structure as shown in Fig. 11 and 12 and also , -that shown in Fig. 10.
It will be seen that the structure shown in Fig. 11 is a perfect structure and may be defined as a foraminous, structure ,~' ' but not necessarily as a screen atructure.
As shown in Fig. 14, a modified discharge electrode ~ -structure shown on the same plane aa that shown in Fig, 1 and this structure comprises a sheet metal plate 102 to which have been spot welded or otherwise aecured bara having generally L-shaped configuration, these bars being designated 104. Th,ese bars 104 are provided with edges 106, each h,aving a plurality of triangu- -lar points 108. These points 108 may be spaced apart as shown in Fig. 15 to vary the flow density in the dîrection of the air flow as indicated by the arrow A in Fig. 15 which corresponds with that of Figs. 2 and 3 of the drawings. The L-shaped bars 104 project from oppoaite sides of the plate lQ2 and all have the triangular points 108 projecting therefrom to provide dia~
charge points. Additionally the plate 102 as shown in Fig. 15 ~ ' is provided with openings 110 thereth,rough, These openings 110 may constitute substantially twenty percent of the area of the plate 102 so as to provide for preasure and flow equalization at opposite sides of the plate and to thereby maintain even flow characteristics adjacent to the wet wall surfaces 26 and 28 of the collector electrodes 22 and 24. ~ ;
It will be seen that th,e concentration of the points - 16 - , ~ ',. ' : . . .
;
~07~;4~38 108 may vary in a direction of the flow A and thereby provide -for a high dènsity corona field ad~acent the inlet between the collector elec- - :
trodes 22 and 24 as described in connection with Fig. 2 of the drawings, the inlet being at the lower ends of the electrodes and thus the plate 102 may be a foraminous plate provided with points extending from opposite sides thereof toward the respective ;
collector electrodes. The structures shown in Figs. 10 to 15 of the drawings are preferably made of Titanium due to the fact that it has been discovered that Titanium provides an unexpected result; namely, that it is very durable in the environment of an electrostatic precipitator.
Heretofore, such discharge electrodes have been made of stainless steel or the like and have eroded away ~uite rapidly, The environmental conditions in an electrostatic precipitator comprise high voltage discharge from the discharge electrodes as well as various viscous and vapor conditions which has heretofore caused erosion of discharge electrodes and which has not been particularly predictable and in accordance with the present invention or discovery, Titanium has been found to be extremely durable under these environmental conditions.
It will be obvious to those skilled in the art that various modifications may be resorted to without departing from the spirit of the invention, ..
: . , . . . , :
- . . .
: . . .. . .
. ~ , ~ " .
lQ76~88 .:
on opposite sides is such that the concentration of these points may be varied in such a manner that the electrical discharge from the discharge electrode may afford a very high corona field density near the inlet of passages between the collector electrodes wherein air laden with foreign matter flows and is ionically charged so as to be driven or attracted to the wet wall surfaces of the collector electrodes.
The discharge electrode means of the invention also provides an aerodynamic effect which causes angular departure 10 of the fluids flowing adjacent to the discharge electrodes. such that the angular departure is directed toward the collector electrodes and thus the aerodynamic effect provided by the dis-charge electrode means of the invention assists the ionic function of the corona field to force the particles carried by : the air flow adjacent the electrodes into contact with the collector electrodes.
1 Further, the invention comprises a discharge electrode ~' means which is either screen like or foraminous so that the :~
aerodynamic function around the electrodes is e~ualized from a :
pressure standpoint to alleviate the possibility of creating a pressure differential at opposite sides of the discharge electrode ~
.i and to thereby change the flow characteristics adjacent to respect-ive collector electrodes at opposite sides of the discharge elect~
rode.
Accordingly, it will be appreciated that the perforate or screen like structure allows an even pressure or flow distri-bution to exist at opposite sides of the discharge electrode and to thereby permit substantially laminar flow of fluids adjacent ~
to the collector electrodes. `
~ 30 Accordingly, it is an object of the present invention to provide a novel screen like or foraminous discharge elec-trode .
' . . . .
'':~ ' ' ' ' , , , ' ' ' ' 1076~L88 means for cooperative functlon with wet wall collector electrodes of an electrostatic preclpitator.
Another object of the invention is to provide a novel screen like or foraminous dlscharge electrode having discharge points on opposite sides thereof which may be varied in concentra~
tion to vary the corona field density in a direction from the inlet to the outlet of an electrostatic precipitator in which the discharge electrode is positioned.
Another object of the invention is to provide a novel ~ -discharge electrode for electrostatic precipitators wherein a screen like electrode structure is formed of expanded metal or the like wherein the cross sectional shape of the bars of the screen like expanded metal are sheared and have rectangular cross section provided with sharp edges to provide for discharge points and further to provide such a structure in which some of ;
: the bars are clipped off to provide terminal stub portions which form discharge points, the stub portions having ends rectangular - in cross section with four corners, all of which are sharp and provide ideal electrostatic discharge teFminals.
Another object of the invention is to provide a screen like discharge electrode for electrostatic precipitators wherein a screen such as formed from expanded metal has an extended cross ;~ ;
section in proportion to its weight and is relatively rigid ; , thereby providing for integrity of the structure in its spaced relation with adjacent wet wall surfaces of the collector : electrodes thus maintaining or providing for efficient establish-`, ment of a corona field and minimizing the possibility of having .. , ~ .
. arcing from the discharge electrode to the collector electrodes. ;
Another object of the invention is to provide a novel discharge electrode for electrostatic precipitators which is made of Titanium and which has been found to be very durable and efficient in an electrostatic precipitator environment.
: iX7 ,:
, ~ ,..... ...... .
.~...... .
. - :.
..... ..
,' . ' 1t)76~
Thus, and in accordance with the present teachings, a discharge electrode for wet wall electrostatic precipitators is provided. The discharge electrode is of hollow cylindrical shape and has annular in cross section foraminous screen like wall structure provided with upper and lower portions. The screen like wall structure comprises expanded metal which has interconnecting bars substantially rectangular in cross section and has corners forming electrostatic discharge points with some of the bars interconnecting each other at an angle. Ths bars are provided with stubs formed by clipping away portions of some of the bars to leave the stubs which have terminal ends forming electrode discharge points. The wall structure which is annular in cross section has opposite surfaces and a pluralityfor discharge points disposed at the opposite surfaces.
The bars of the screen like structure are all integral with each other and disposed in a group of parallelograms, each parallelogram having a pair of parallel bars constituting long sides of a respective parallelogram and also a pair of spaced apart parallel bars constituting short sides of each parallelo-gram. The stubs pro~ect at an angle to and in opposite directionsfrom the-intermediate portions of the long side, the stubs being the discharge points, and the discharge points in the lower portion being highly concentrated with the concentration gradually diminishing toward the upper portions.
.
~ 6a-~ `.
-, . ~
11~)76~8~
Another object o~ the invention is to provide a discharge electrode for electrostatlc precipitators having novel aerodynamic Eunctions which cooperate with the electrostatic functions to mechanically move foreign matter in an alr stream ; in addition to the ionic forces in attaining collection of the foreign particles on the collector electrodes.
Another object of the invention is to provide a dis- ;
charge electrode for electrostatic precipitators which, due to its aerodynamic function, causes foreign particles in an air stream to be aerodynamically projected toward the collector electrodes and while at the same time the discharge electrode ;~
structure does not upset the desired flow or pressure characteris-tics of the fluid at opposite sides thereof and ad~acent to respective wet wall surfaces of collector electrodes.
Another object of the invention is to provide a novel discharge electrode means for electrostatic precipitators ~hich may be directly applicable to either annular in cross section electrode assemblies or to the conventional flat electrode ~ :
assemblies.
` 20 Another object of the invention is to provide a ' variety of structures which may be adapted for use in collector electrodes of electrostatic precipitators and mainly structures , which are either screen like or foraminous with discharge points on opposite sides thereof and sufficient openings or perfora-tions so as to maintain even pressure and flow distribution :- .
at opposite sides of the discharge electrode so as to avoid : upsetting the desired laminar flow characteristics for efficient `;
aerodynamic and ionic collection of particles on the wet wall surfaces of the collector electrodes.
":; ' ,.
, . .
.: : ' ~076488 Further ob~ects and advantages of the invention may be apparent from the following specification, appended claims and accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a fragmentary top or plan view of an electrode assembly of an electrostatic precipitator showing a discharge electrode means between a pair of collector electrodes and showing suspension means for the discharge electrode means;
Figure 2 is a side elevational view of the structure shown in Fig. 1 and showing portions broken away and in section to amplify the illustration.
Fig. 3 is an enlarged fragmentary sectional view of -~
the discharge electrode means taken from the line 3-3 of Fig. 2;
Fig. 4 is a fragmentary sectional view taken from the line 4-4 of Fig. 3 showing the suspension means for the dlscharge electrode;
Fig. 5 is an enlarged fragmentary view of screen like structure of the discharge electrode as shown in Fig. 4~
Fig. 6 is an enlarged fragmentary sectional view taken from the line 6-6 of Fig. 5 showing a cross section of the screen like electrode structure disclosed in Fig. 5;
Fig. 7 is an enlarged fragmentary view similar to Fige 5 showing a modified form of the discharge electrode screen structure;
Fig. 8 is an enlarged sectional view taken from the line 8-8 of Fig. 7 showing the cross sectional shape of the bars of -the screen like structure shown in Fig. 7;
Fig. 9 i8 an enlarged fragmentary sectional view taken from the line 9-9 of Fig. 7;
Fig. 10 is a fragmentary plan view taken in the same direction as Fig. 1 showing an end of a modified form of the , ~769~88 discharge electrode structure of the inventlon;
Fig. 11 is a view similar to Fig. 6 showing a further modified form oE the discharge electrode structure of the invention;
Fig. 12 is a fragmentary sectional view taken from the line 12-12 of Fig. ll;
Fig. 13 is a fragmentary sectional view taken from the line 13-13 of Fig. 12;
Fig. 14 is a view similar to Fig. 10 showing a further modified form of the discharge electrode structure of the inven-tion; and Fig. 15 is an enlarged fragmentary sectional view taken -~ ~
from the line 15-15 of Fig. 14. ~ -DESCRIPTION OF THE PREFERRED EMBODI~ENTS `
As shown in Figs. 1 and 2 of the drawings, the electrode means for wet wall electrostatic precipitators of the invention comprises a discharge electrode 20 and a pair of collector electrodes 22 and 24. The collector electrodes 22 and 24 are provided with respective wet wall collector surfaces 26 and 28. These surfaces are adapted to operate with a film of liquid flowing downward on them. ~
As shown in Fig. 2 of the drawings, the discharge -electrode 20 is suspended by a plurality of rods 30 which are ;
supported on candelabra arms 32 which are supported in ~uxta- ;
position by means not shown. The discharge electrode 20 is provided with a screen like or foraminous structure 34 having an annular ring like frame member 36 at its upper end to which the suspension rods 30 are secured by welding or other suitable means.
The screen like structure 34 is preferably welded or fused to the ring like frame 36 and this screen like structure 34 g , .. .. ~ ........................................................ .
., ,: , . :
~' ' , ' , 107~8 Of the discharge electrode 20 at its lower end is provided with a ring shaped frame member 38 to which the screen like structure 34 is preferably welded.
As shown in Fig. 4, it will be seen that the suspension rods 30 are provided with externally screw threaded portions 40 on which nuts 42 and 44 are screw threadably disposed. These nuts 42 and 44 are vertically screw threadably adjustable on the screw threaded portion 40 of each of the rods 30 and each screw threaded portion of each rod 30 passes through a respective horizontal member 32 which is preferably tubular in cross section.
The nut 44 on each rod 30 engages an upper side of the respective member 32 and each nut 42 on each suspension rod 30 engages a lower portion of the respective member 32 so that the suspension of the hollow cylindrical discharge electrode may be adjusted in order to attain alignment suspension of the discharge electrode concentrically between the respective wet wall surfaces 26 and 28 of the collector electrodes 22 and 24. The spacing is critical to provide efficient Eormation of a proper corona field and to avoid local and continuous arcing between the dis-charge electrode and the collector electrodes to thereby achieverandom sparking throughout the precipitator. Accordingly, the adjustability of the suspension rods 30 allows the collector electrode to be properly aligned in direct concentric and parallel-- ism with the respective wet wall surfaces 26 and 28 hereinbefore described.
As shown in Fig. 2 of the drawings, the electrode struc-ture when in operation receives air or gases flowing in the dir-ection of the arrows A in Fig. 2 of the drawings upwardly between the wet wall surfaces 26 and 28 and at opposite sides oE the discharge electrode 20, it being seen that the discharge elec-trode 20 and the collector electrodes 22 and 24 are annular in 107~88 cross section concentric structures.
Referring to Fig. 3 of the drawings, it will be seen ~ ~;
that the screen like structure 34 of the discharge electrode 20 comprises generally a diamond shaped arrangement of bars designated 46 which are all integral with each other. The screen like struc- ,, ture 34 as shown in Fig. 3 being an expanded metal structure initi-ally formed and sheared from a flat sheet of metal. Some of the 'i bars 46 are clipped off to form stubs 48 which form electrical . ;. ~, .
discharge points and, as shown in Fig. 3, a substantially greater ~ , , ' number of these discharge points 48 are provided near the lower or inlet end of the discharge electrode so as to provide a high -~
density corona field at the lower inlet end as indicated by the arrows A in Fig. 2 of the drawings. The lower edge of the '~
ring shaped frame member 38 being provided with a plurality of '' ~ ' points 50 similar to those provided by the stubs 48j it being noted that the clipping pattern may be varied in order to provide a greater or lesser number of these discharge points and thus the corona field density may be varied in the direction of flow of particle laden air or gas which passes between the discharge ~;~
electrode 20 and the adjacent wet wall surfaces 26 and 28 of the -collector electrodes 22 and 24.
The screen like structure 34 at the upper and lower ends ,~, thereof is maintained in a substantially accurate rigid annular form by the ring shaped frame members 36 and 38 and these members 36 and 38 as shown in Fig. 4 are preferably tubular members of flattened cross sectional shape.
The suspension rods 30 as well as the frame rings 36 ' ~ -~
and 38 and the screen like structure 34 may all be made of stainless steel or the like, however, Titanium is the preferred material from whlch these parts are to be made inasmuch as Titanium has been found to be very durable and efficient ",,, , , ,, , : , , 1 ~7f~
in an electrostatic precipitator handling corrosive gases.
The screen like structure 34 made of expanded metal such as shown in Fig. 5~ comprises integral, interconnecting parallel-ograms, each having four bars designated 52, 54, 56 and 58, the bars 52 and 54 being relatively short and the bars 56 and 58 being relatively long, the pattern being such that bars similar to the bars 52 and 54 are clipped to provide the stubs 48 also shown in Fig. 3 of the drawings, and these stubs project in opposite directions from intermediate portions of the long bars 56 and 58 of each parallelogram all of which are integral with each other and generally formed of expanded metal.
The cross sectional shape of each of the bars 52, 54, ~
56 and 58 is generally rectangular in cross section as shown in - ~ ; ;
Fig. 6 of the drawings and corresponds to the ends of the points 48 disclosed therein. All of the parallelogram portions of the screen pattern are integral at the areas designated 60, all of which is shown in Figs. 5 and 6 of the drawings. -As shown in Fig. 6 of the drawings, the expanded metal configuration is such that the bars generally designated 46 in Fig. 3 of the drawings are disposed in an undulating relationship such as to provide a substantially more rigid section than would be the case of the sheet of metal had it been left in flat condition. Accordingly, the increased section modulus of the structure as shown in Fig. 6 provides for substantial rigidity of the structure which is a relatively lightweight as-sembly of bars relative to the overall size and area thereof.
This undulating structure shown in Fig. 6 having a substantial section modulus is quite rigid and particularly so when formed into the circular in cross section structures shown in Figs. 1 and 2 and thus affords rigidity compatible with the accuracy of spacing required of the discharge electrode 20 relative to ~ ' ~
, . . , . ~ ~: , :
10764~38 :
the adjacent wet wall surfaces 26 and 28 of the collector elec-trodes 22 and 24. ~`
In ~he modification of the screen structure 34 shown in Fig. 7 of the drawings, the expanded metal is arranged in a different clipped pattern to provide the point forming stubs 48.
This pattern comprises a plurality of parallelograms including ~-one generally V-shaped portion 62 and a second V-shaped portion 64. The V-shaped portion 62 having an apex 66 and the V-shaped ;~
portion 64 having an apex portion 68. These apex portions 66 , and 68 being opposed to each other and each of the parallelograms consisting of the V-shaped portions 62 and 64 being integral with each other at areas 70 which correspond with the area 60 ~
as shown in Fig. 5. ~ -The V-shaped portions 62 and 64 are provided with the clip- ~ -ped stubs 48 at areas intermediate the integral portions 70 and ~`
the apex portion 66. Thus the stubs 48 are disposed at inter- ~ ~-mediate portions between the apex portions and the portions 70 which are integral with adjacent parallelograms all generally formed by the hereinbefore mentioned bars 46 of the expanded metal and depending upon the clipping of these bars at particular areas to form the stubs 48 which act as discharge points for the discharge electrode 20 of which the screen like structure 34 is a primary part.
~s shown in Fig. 8 of the drawings, each bar 46 is pro- ~, vided with four corners 72. These corners being sharp due to the fact that the expanded metal is sheared in the initial forming and these corners 72 of the bars 46 are all capable of performing as discharge points. Thus due to the undulating structural ar-rangements as shown in Figs. 6 and 9 of the drawings, the corners of the intersections 60 and 70 all function as discharge points since they are at the lateral extremities of the screen structure .
,.': . - , . . .
... .
1~7641~i18 34. Thus the screen like structure 34 of the discharge electrode 20 when Eormed of expanded metal is capable of providing for a great many electrical discharge points or sharp edgea to provide for a high density corona field and the open mesh of the structure also has aerodynamic functional characteristics which cause the Elow to depart away from the screen like structure 34 at an acute angle approximating an angle in the range of four to five degrees and thus the aerodynamic function causes gas flow and the flow of particulate matter to progress away from the screen like structure and toward the respective wet wall surfaces 26 and 28 of the collector electrodes 22 and 24, This aerodynamic ef- ~ -fect is cooperative with the ionic effect on the particles for forcing them toward the wet wall surfaces 26 and 28 of the collector electrodes 22 and 24.
It will be seen that each of the intersectiona 60 as shown in Fig. 6 is provided with four corner edges 74 which may ;~
serve as discharge points. These points 74 being at the lateral extremities of the screen structure 34 and the intersections 70 shown in Fig. 9 of the drawings are provided with sharp corner ~-edges 76 which are also at the lateral extremities of the screen structure 34 and thus they serve as discharge points for the dis-charge electrode 20.
~ dditionally, it will be seen that similar sections 78 as shown in Fig. 7 of the drawings are disposed between the stubs 48.
These sections 78 are provided with corners 80 similar to the -corners or edges 76 and they also provide substantial discharge points. Likewise portions 82 form intersections between the stubs 48 shown in Fig. 5 of the drawings, and these portions 82 have a similar cross section to the integral portion 60 shown in Fig. 6 and they also have similar corners structurally equiva-lent to the corners 74 which are at the lateral extremities of ,: . . . . . . . . ............... . .
' :' , ,: , ,.'' ~ ' ' :':
.
107~4t~
the screen like structure 34 and thus they also provide discharge point capabilities.
In ~he modification as shown in Fig, 10 of the drawings, a discharge electrode 88 is of annular form but shown ;
fragmentarily and Fig. 10 discloses the discharge elect~ode in the same plane as that shown in Fig. 1. This discharge electrode ;
: .
88 is formed of a sheet of metal having generally triangular taba ;; -~90 punched therefrom and extending in opposite directions at opposite sides oE the plate to form discharge points~ These tabs 90 being similar to the tab structures as will be hereinafter des~
cribed in connection with the disclosure of Fig. 11 and 12 of the drawings.
It will be seen that the plane of these tabs 90 may be at right angles to the direction of flow and the openings from which the tabs are punched out provide for equalization of pressure to maintain proper flow distribution as will be hereinafter des--cribed in connection with the disclosure of Figs. 11 and 12.
As shown in Fig. 11 a sheet of metal designated 92 is provided with a plurality of punched out openings 9~ from which tabs 96 are projected laterally of the plate~ These tabs being shown in Figs. 12 and 13 of the drawings and are generally triangular and disposed in opposite directions from the sheet 92.
The tabs 96 are each provided with an apex point 98 and thus provide discharge points of opposite sides o e the sheet 92.
As shown in Figs. 11 and 12 these tabs 96 are parallel to the axis of flow indicated by the arrow A which corres-pond with the arrows A in Figs. 2 and 3 of the drawings. The structure shown in Fig. 10 of the drawings has the tabs 90 dis-posed at right angles generally to the direction of flow or may have them at an angle to the flow if desired but depending upon certain requirements of electrostatic precipitators having .
' . ' ' ' , , ~ , , ~ ' . ' , . , ... . ~, .
~0769L8~
varying configurations which may be desired. ~, It will be seen that each of the tabs 96 when punched ~;
out of the plate 92 leaves a respective opening 100 and these openings 100 may approximate twenty percent of the overall area of the plate 92 so as to provide for equalization oE preasure and flow characteristics at opposite sides oE a discharge electrode formed of such structure as shown in Fig. 11 and 12 and also , -that shown in Fig. 10.
It will be seen that the structure shown in Fig. 11 is a perfect structure and may be defined as a foraminous, structure ,~' ' but not necessarily as a screen atructure.
As shown in Fig. 14, a modified discharge electrode ~ -structure shown on the same plane aa that shown in Fig, 1 and this structure comprises a sheet metal plate 102 to which have been spot welded or otherwise aecured bara having generally L-shaped configuration, these bars being designated 104. Th,ese bars 104 are provided with edges 106, each h,aving a plurality of triangu- -lar points 108. These points 108 may be spaced apart as shown in Fig. 15 to vary the flow density in the dîrection of the air flow as indicated by the arrow A in Fig. 15 which corresponds with that of Figs. 2 and 3 of the drawings. The L-shaped bars 104 project from oppoaite sides of the plate lQ2 and all have the triangular points 108 projecting therefrom to provide dia~
charge points. Additionally the plate 102 as shown in Fig. 15 ~ ' is provided with openings 110 thereth,rough, These openings 110 may constitute substantially twenty percent of the area of the plate 102 so as to provide for preasure and flow equalization at opposite sides of the plate and to thereby maintain even flow characteristics adjacent to the wet wall surfaces 26 and 28 of the collector electrodes 22 and 24. ~ ;
It will be seen that th,e concentration of the points - 16 - , ~ ',. ' : . . .
;
~07~;4~38 108 may vary in a direction of the flow A and thereby provide -for a high dènsity corona field ad~acent the inlet between the collector elec- - :
trodes 22 and 24 as described in connection with Fig. 2 of the drawings, the inlet being at the lower ends of the electrodes and thus the plate 102 may be a foraminous plate provided with points extending from opposite sides thereof toward the respective ;
collector electrodes. The structures shown in Figs. 10 to 15 of the drawings are preferably made of Titanium due to the fact that it has been discovered that Titanium provides an unexpected result; namely, that it is very durable in the environment of an electrostatic precipitator.
Heretofore, such discharge electrodes have been made of stainless steel or the like and have eroded away ~uite rapidly, The environmental conditions in an electrostatic precipitator comprise high voltage discharge from the discharge electrodes as well as various viscous and vapor conditions which has heretofore caused erosion of discharge electrodes and which has not been particularly predictable and in accordance with the present invention or discovery, Titanium has been found to be extremely durable under these environmental conditions.
It will be obvious to those skilled in the art that various modifications may be resorted to without departing from the spirit of the invention, ..
Claims (3)
1. A discharge electrode for wet wall electrostatic precipitators; said discharge electrode being of hollow cylindrical shape and having annular in cross section foraminous screen like wall structure provided with upper and lower portions; said screen like wall structure com-prising expanded metal having interconnecting bars sub-stantially rectangular in cross section and having corners forming electrostatic discharge points; some of said bars interconnecting each other at an angle; said bars being pro-vided with stubs formed by clipping away portions of some of said bars to leave said stubs having terminal ends forming electrode discharge points; said annular in cross section wall structure having opposite surfaces and a plurality of discharge points disposed at said opposite surfaces; said bars of said screen like structure all integral with each other and disposed in a group of paral-lelograms; each parallelogram having a pair of parallel bars constituting long sides of a respective parallelogram and also a pair of spaced apart parallel bars constituting short sides of each parallelogram; and said stubs projecting at an angle to and in opposite directions from intermediate portions of said long sides;
said stubs being said discharge points, the discharge points in said lower portion being highly concentrated with the concentration gradually diminishing towards said upper portions.
said stubs being said discharge points, the discharge points in said lower portion being highly concentrated with the concentration gradually diminishing towards said upper portions.
2. The invention as defined in Claim 1, wherein said stubs of adjacent parallel long sides of said parallelograms being in substantially aligned relation to each other.
3. The discharge electrode of Claim 1, in which said bars are arranged in undulating relation to add rigidity to to the screen like wall structure and provide aerodynamic effects on gases moving upwardly between the discharge electrode and the wet walls of the precipitator.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US56569275A | 1975-04-07 | 1975-04-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1076488A true CA1076488A (en) | 1980-04-29 |
Family
ID=24259708
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA246,817A Expired CA1076488A (en) | 1975-04-07 | 1976-03-01 | Electrode means for wet wall electrostatic precipitators |
Country Status (12)
| Country | Link |
|---|---|
| JP (2) | JPS51126577A (en) |
| AU (1) | AU501227B2 (en) |
| BE (1) | BE840255A (en) |
| CA (1) | CA1076488A (en) |
| DD (1) | DD126044A5 (en) |
| DE (1) | DE2615135C2 (en) |
| ES (1) | ES446763A1 (en) |
| GB (1) | GB1538153A (en) |
| GR (1) | GR60056B (en) |
| NZ (1) | NZ180179A (en) |
| PT (1) | PT64949B (en) |
| ZA (1) | ZA761258B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3445407A1 (en) * | 1984-12-13 | 1986-06-19 | Robert Bosch Gmbh, 7000 Stuttgart | DEVICE FOR CLEANING GASES |
| US20230100405A1 (en) * | 2021-09-21 | 2023-03-30 | Nestec, Inc. | Electrostatic precipitator with rotary collecting walls |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB237282A (en) * | 1924-07-18 | 1926-03-18 | Maschb Ag Elsass | Improvements in coke-ovens and the method of operating the same |
| GB255490A (en) * | 1925-07-18 | 1926-12-09 | Siemens Schuckertwerke Gmbh | Improvements in or relating to electrodes for the electric purification of gas |
| US2064960A (en) * | 1932-03-05 | 1936-12-22 | Estelle T Thorne | Method of and apparatus for cleaning gases |
| DE1113444B (en) * | 1958-10-13 | 1961-09-07 | Bayer Ag | Electrostatic precipitator for the purification of chlorine gas produced during the electrolysis of aqueous alkali halide solutions |
| FR1544887A (en) * | 1967-09-29 | 1968-11-08 | Cit Alcatel | Improvements to smoke and gas purifiers |
-
1976
- 1976-03-01 CA CA246,817A patent/CA1076488A/en not_active Expired
- 1976-03-01 GR GR50212A patent/GR60056B/en unknown
- 1976-03-02 NZ NZ180179A patent/NZ180179A/en unknown
- 1976-03-02 ZA ZA761258A patent/ZA761258B/en unknown
- 1976-03-18 GB GB10999/76A patent/GB1538153A/en not_active Expired
- 1976-03-25 PT PT64949A patent/PT64949B/en unknown
- 1976-03-31 BE BE165743A patent/BE840255A/en unknown
- 1976-04-01 AU AU12556/76A patent/AU501227B2/en not_active Expired
- 1976-04-06 JP JP51038677A patent/JPS51126577A/en active Pending
- 1976-04-07 ES ES446763A patent/ES446763A1/en not_active Expired
- 1976-04-07 DD DD192250A patent/DD126044A5/xx unknown
- 1976-04-07 DE DE2615135A patent/DE2615135C2/en not_active Expired
-
1978
- 1978-10-31 JP JP1978150243U patent/JPS5639556Y2/ja not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| AU501227B2 (en) | 1979-06-14 |
| PT64949A (en) | 1976-04-01 |
| JPS54104575U (en) | 1979-07-23 |
| PT64949B (en) | 1977-08-25 |
| BE840255A (en) | 1976-07-16 |
| AU1255676A (en) | 1977-10-06 |
| GR60056B (en) | 1978-04-04 |
| DE2615135C2 (en) | 1984-07-19 |
| ZA761258B (en) | 1977-02-23 |
| DE2615135A1 (en) | 1976-10-21 |
| NZ180179A (en) | 1979-03-28 |
| GB1538153A (en) | 1979-01-10 |
| JPS51126577A (en) | 1976-11-04 |
| ES446763A1 (en) | 1977-06-01 |
| JPS5639556Y2 (en) | 1981-09-16 |
| DD126044A5 (en) | 1977-06-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |