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Publication numberUS3898060 A
Publication typeGrant
Publication dateAug 5, 1975
Filing dateJan 28, 1974
Priority dateJan 28, 1974
Publication numberUS 3898060 A, US 3898060A, US-A-3898060, US3898060 A, US3898060A
InventorsStarbuck Herman S
Original AssigneeStarbuck Herman S
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Electrostatic precipitator
US 3898060 A
An electrostatic precipitator drum comprises a plurality of duplicate precipitator cell sections which are enclosed by a housing having a first chamber which is in axial communication with certain of the cells and at least one other chamber which is in radial communication with certain other of the cells. Means are provided for generating an electrostatic field in the cells in communication with the first chamber and means are provided for deactivating and scrubbing the cells in communication with the second chamber.
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Description  (OCR text may contain errors)

0 United States Patent 1 1 1111 3,898,060 Starbuck Aug. 5, 1975 {54] ELECTROSTATIC PRECIPITATOR ZbULUf/l 9/[952 Hahn .1 SS/l l3 -5172.747 3/!965 Nodolf 55/124 5 3183,64) 5/1965 T6116: 1 .1 55/390 Remington cmcmnlm Ohm 3,500,614 3/1970 sec .1 55/145 4524?. 22 i d J 2 I74 PIi/HUI') lirumincrBernard NOZiCk Altar/10y, Agent or Firm.l. Warren Kinney, Jr, [2 l] Appl. No.: 437,338

[57] ABSTRACT [52] US. Cl. 55/110; 55/1 13; 55/1 [8; An electrostatic precipitator drum comprises a plural- 55/126; 55/138; 55MB); 55/]41; 55/l46; ity of duplicate precipitator cell sections which are en 55/ 149; 55/l50; 55/154; 55/290 Closed by a housing having a first chamber which is in {51] Int. Cl. 303C 3/09 axial communication with certain of the cells and at [58] Field of Search SS/l 3, l4. 1 l0, 1 13 1 l7, least one other chamber which is in radial communi- 55/l l8, l2() 123, l24 I26 I3% l3), l4], cation with certain other of the cells Means are pro- 140. I45, l46 149, [54. 290 vided for generating an electrostatic field in the cells in communication with the first chamber and means [561 References Cited are provided for deactivating and scrubbing the cells UNITED STATES PATENTS in COmmuniCatiOn with the second chamber. 2582133 1/1952 Karlsson 55/113 [5 Claims, 9 Drawing Figures PATENIEU AUG 5 ms SHEET FIG-l 5) S '51 1 U 6 O PATENTED RUB 51975 SHEET PAH N II Alli; 5 W5 FIVG-B ICRI ICRZ IP am 1 I- am if INS? ICRJ Y ZCRS IMS5

uaawan M w 7/ nus TIME HEM INDEX STOP "m mum omv Zwx z: V r A if m 7 our |T| mm C C C C C 0 I I I c c 0 c c c f, Um c c 0 c c c V06 cm: on on OFF on on on PM 2/0 2cn2 0 0 c 0 o o 2 G 2 I OFF OFF on OFF err on 7/2 HLL 2/4 3CR2 C C 0 0 C C i I F on on on on on 0 mve arr OFF on OFF on OFF m2 0 c o c c c 2 7 Y 0 on on OFF on on on 220 224 5on2 0 o c o o o 3 1 A, y c on OFF on on on 0FF VALVE om OPEN sum om om om IIISI my q l msz o c c c 0 0 INS! 0 o c o o 0 was 0 o c o o 0 cm on on on OFF OFF orr 2.72 20:15 0 q c o o L on OFF on err on r znsz 216 ms c c o c c c L L i, znsz c o o o o c Ill)! 0 o q 7 g c o g"; 215 M an on on on on on m m l 211 0 o c o o I h o m on on OFF OFF on OFF m2 0 c c c o 0 2 msa c c o p H c g 1 9E TA 0 FF 1 m a? -Q n T s m n 0 w T m 250 an o o c o o 0 {Q 2 -9- w on err on ort gr; or? 252 254 4n 0 o c o r q o u on OFF on err on on FL 'TTP OSTA TIC PRECIPITATOR BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is related to electrostatic precipitators for removing contaminants from flowing fluids, more particularly to that class of precipitators adapted for use in removing pollutants from a fluid medium by exciting the pollutants with an electric charge and collecting them at an oppositely charged cnllecting surface. The invention is directed to a precipitator hav ing means for cleaning the contaminant buildup from the collecting surface while continuously removing par ticulate matter from a fluid flowing therethrough.

2. Description of the Prior Art Electrostatic precipitators are known in the art and generally fall into one of two distinct categories. The first is a single-stage unit wherein solid particles in a flowing gas are ionized by passing the particle-laden gas through an electrostatic field set up between a spaced pair of charged electrodes which ionize each of the particles with a common charge. Where all of the particles are, for example, positively charged the flowing gas next passes through an electric field including a series of negatively charged collecting plates or electrodes. The negative charge attracts the positively charged particles, generating a precipitating action collecting and removing the particulate matter from a gas flowing therethrough.

The second category of precipitators is generally referred to as a two-stage unit and includes an ionizing zone similar to that of single-stage units. The collecting zone comprises a plurality of alternately spaced collect ing and accelerating electrodes. The collecting electrodes, as before, are charged at a polarity opposite the polarity of the charge carried by the particulate matter and serve to entrain the particles passing through the collecting zone. The accelerating electrodes are charged with a polarity identical to the polarity of the charge carried by the particulate matter and serve to accelerate the particles toward the collecting elec trodes by utilizing the repelling force generated by the similar charges.

While both types of precipitators are in common usage, the two-stage precipitator is more efficient, having shown in practice an ability to remove as much as 99 percent of the solid pollutants from a flowing gas when the collecting plates are clean. However, as particles build-up on the collecting electrodes the efficiency of both systems is drastically reduced, sometimes dropping as much as ten percent in a matter of a few hours. Therefore, in order to maintain an efficient operation, the electrodes must be periodically cleaned.

Heretofore the systems often required shut-down of the entire operation before the electrodes could be scrubbed. Later precipitators include an endless movable chain of collector plates wherein one portion of the chain is immersed in a body of oil or the like for soaking the accumulated particles from the plates so immersed, successive portions of the chain being thus periodically cleaned. More recent developments include a rotating drum precipitator having a plurality of like cells, each cell containing a series of collecting electrodes wherein certain of the cells are in a cleaning cycle while others are in an operating cycle, providing a precipitator that is always operable while periodically cleaning certain of the collecting electrodes. Certain of these systems utilize cleaning apparatus which includes means for simply rapping or causing a vibration in the collecting electrodes to shake the particles loose therefrom, as exemplified by US. Pat. Nos. 2,717,052 and 2,712,362. Certain other systems direct a stream of cleaning fluid into the collecting electrodes, for washing the collected particles into a suitable receptacle, as exemplified by U.S. Pat. Nos. 2,582,133 and 2,609,061. U.S. Pat. Nos. 2,609,061 and 3,049,848 disclose precipitators which include means for deactivat ing the electrodes during the cleaning cycle, whereas U.S. Pat. No. 2,887,175 discloses a system wherein the full normal charging voltage on the precipitator electrodes may he maintained during the entire cleaning cycle.

Generally, the electrodes of prior art systems comprise an outer hollow tube charged with a polarity op posite that of the ionized particles, herein referred to as an collecting electrode, and a thin wire component extending axially through the hollow tube and charged with a polarity identical to that of the ionized particles, herein referred to as a accelerating electrode. Certain of the prior art systems, as illustrated, for example, in FIG. 12 of U.S. Pat. No. 2,582,133 include parallel plate electrodes wherein the rotary drum includes radially extending support members forming a web or a support structure for holding a web-like series of concentric, arcuate or flat electrode plates, having a series of similarly or oppositely charged electrode plates inserted therebetween.

In each of these prior art systems, the cleaning solution as well as the gaseous medium is directed axially through the precipitating chamber, preventing the full force of a pressurized cleaning fluid from directly attacking the surface of the collecting electrodes. Further, each of these systems are costly to manufacture and assemble due to the rigidity required to assemble the bulky electrode configurations.

The present invention provides an improvement over known systems and includes a novel configuration for the accelerating and collecting electrodes, permitting inexpensive manufacture as well as easy assembly of the precipitator in an economical and efficient manner.

' The electrodes are designed and placed in a manner permitting axial flow of a fluid medium therethrough, while permitting a cleaning solution to be directed radially into the electrodes generating a more efficient and thorough cleaning operation by allowing a pressurized cleaning fluid to strike the collecting plates at an acute angle, rather than flowing in a path parallel to the sur face of the various plates. While the embodiment illustrated and described is a two-stage precipitator unit, it should be understood that the system disclosed is readily adapted to other units without departing from the scope and spirit of the invention.

SUMMARY OF THE INVENTION The present invention comprises a precipitator system having an inlet port adapted to be coupled to a conduit carrying contaminated fluid, generally in the form of a particle laden gaseous medium, wherein a transition section such as an intake plenum or the like reduces the velocity of the incoming gas and directs it through a pre-filter where large particulate matter is removed. The remaining particles in the gas are then excited with a common charge at an ionizing section,

the ionized particles flowing with the gas into a precipitator unit where they are attracted to and collected on a series of charged electrodes. Generally, the precipita tor section is of the two-stage type wherein electrodes bearing the same charge as the ionized particles serve to accelerate the precipitating process. The decontaminated gas is then drawn through an after-filter which removes remaining particles from the flowing gaseous medium. A second transition section, for example. an output plenum, increases the velocity of the gas and discharges it through an exhaust port into a clean gas conduit.

The precipitator is in the general configuration of a rotatable drum having a plurality of identical sectors each defining a precipitator cell comprising a plurality of parallel collecting electrodes interspersed with ac celerating electrodes, the drum enclosed by a housing having a first chamber in axial communication with certain of the cells and having inlet and outlet ports for axially directing a particleladen gas therethrough. The housing includes a second chamber which is in radial communication with certain other of the cells. Those cells in communication with the first chamber are activated with an electrical charge which generates an electrostatic field for entraining ionized particles carried by the gas passing therethrough. Those cells which are in communication with the second chamber are deactivated and isolated from the axial flow of gas.

A pneumatic seal is utilized to isolate the cells in communication with each of the various chambers from one another. The seal may be selectively inflated and deflated, permitting free rotation of the drum when the seal is in a deflated condition. The deactivated cells are cleaned and dried while sealed from the remainder of the precipitator unit, after which the pneumatic seal is deflated, the drum is rotated, indexing the cells with respect to the various chambers, displacing the newly cleaned cell with the dirtiest cell in the collecting sec tion.

Each cell of the precipitator includes a pair of angularly spaced primary support electrodes radiating out ward from the center of the drum. the angular displacement between each adjacent pair of radial supports being equal, defining a drum comprising a plurality of duplicate cell sectors. A graduated series of electrode plates nested in each cell in a stacked, parallel arrange ment are each defined by a pair of substantially flat walls joined at a common apex. the dihedral angle so formed being equal to the included angle between each pair of adjacent primary support electrodes. The apices of the plates each fall on a common radius of the drum, bisecting the sector defined by two adjacent primary electrodes. The plates with the primary electrodes de fine both the accelerating and collecting electrodes of the precipitator chamber.

The outermost plate of each series is spaced from the sector-defining primary plates by a set of insulator spacers, thereby providing electrical isolation. The hub of the drum and the primary plates are excited with a charge of one polarity, i.e., grounded, and the outermost plate is excited with a charge of the opposite polarity. Successive plates are alternately electrically coupled to the primary plate or the outermost plate, providing an electrostatic field therebetween.

The successive plates in each series are properly spaced from one another by spacers which provide electrical links between alternate plates. This is achieved by utilizing conducting spacers of a length equal to the distance between two plates, each spacer passing through a clearance opening provided in an adjacent plate. The clearance opening is sufficient to preelude flashover or arcing between plates when the cell is activated. Therefore, only one plate of each polarity need be externally coupled to a power source in order to activate the entire electrostatic field provided by each cell. The plates are held in position by a retainer ring extending about the periphery of the drum, wherein the last plate of the series is held in compression thereagainst.

Therefore, it is an object of the present invention to provide a housing having a chamber in axial communication with and a chamber in radial communication with certain cells of a rotatable precipitator drum.

It is further an object of the present invention to provide an improved electrostatic precipitating system that is simultaneously in an operating and cleaning mode, wherein cells being cleaned are deactivated and sealed from those in an operating cycle.

It is further an object of the present invention to provide an electrostatic precipitator that is inexpensive to manufacture and which may be easily and efficiently assembled utilizing the minimum number of electrical couplings to affect an electrostatic field for precipitating ionized particles from flowing gases.

Other objects and features of the invention will be readily apparent from the accompanying drawings and description.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an elevation view of an electrostatic precipitator system incorporating the features of the present invention.

FIG. 2 is a section view taken on line 22 of FIG. I, illustrating in detail the features of the present invention.

FIG. 3 is a section view taken at line 3-3 of FIG. 2, illustrating in detail the pneumatic seal arrangement utilized in the preferred embodiment here illustrated.

FIG. 4 is a section view of the pneumatic seal in an inflated condition, taken at line 44 of FIG. 3.

FIG. 5 is a view similar to FIG. 4, illustrating the pneumatic seal in a deflated condition.

FIG. 6 is an exploded view of one cell of the electrostatic precipitator of FIG. 2, enlarged for clarity of detail and understanding.

FIG. 7 is a schematic diagram ofa power and control circuit for ionizing the solid particles contained in a flowing gas and for activating the collector plates of the precipitator.

FIG. 8 is a schematic diagram of an electrical circuit for controlling the cleaning and drying apparatus of the present invention.

FIG. 9 is a diagrammatic illustration of one cell of the precipitator drum, showing the relationship of the various electrode plates.

DETAILED DESCRIPTION OF THE DRAWINGS The preferred embodiment of the present invention is shown generally in FIG. I and includes an intake plenum 10 adapted to draw particle laden gaseous medium 9 or other contaminated fluid through input port I l by means of blower 28. The intake plenum increases the volume of the entering gas, thereby reducing its velocity to a predetermined level and increasing the efficiency of the overall system by retaining the gas therein for a longer period of time. The gaseous medium is next drawn through pre-filter 12 where larger particulate matter is removed. The pre-filter may be one of any of many well-known, commercially available mechanical filters of common usage in the art, for example a wire screen mesh or fiber-fill filter generally adapted to collect particles of greater than fifteen microns in size. After the gas passes through the prefilter, particles too small to be there entrapped are drawn with the gas into ionizing chamber 14 where a high voltage source housed at 15 charges each particle flowing therethrough. An example of circuitry utilized to charge the particulate matter is illustrated in FIG. 7 and is hereinafter discussed in detail. After ionization, the particles will each be excited with a charge of like polarity and will flow with the carrier gas through collector cells 3545 contained in the electrostatic preeipitator chamber 16, see FIG. 2.

Each collector cell includes a plurality of collector plates S053 and 60, adjacent plates carrying charges of opposite polarity and alternate plates carrying charges of like polarity, see particularly FIG. 6. An exemplary circuit for charging the collector plates is illustrated in FIG. 7 and is herein discussed in detail. The particle laden gas passes through preeipitator 16 in the direction of arrow 8" and the ionized particles are either attracted or repelled by the various charged plates, depending upon the polarity of their respective charges, as is typical with two-stage preeipitator units.

The decontaminated gas is next drawn from the electrostatic preeipitator and into after-filter 26. Generally. the after-filter 26 is simliar to pre-filter 12 in that it serves to mechanically remove particles from the gas, in the event such particles escape through the precipitator chamber. However, various other after filters are often incorporated in precipitating systems, and the after-filter is often held at ground potential to remove any ionized particles which escape through chamber l6, combining mechanical and electrostatic filtering actions. Generally, electrostatic precipitators are con structed to collect particles of less than fifteen microns in size, larger particles being easily collected by mechanical apparatus. A blower 28 draws the gas into output plenum 30, which reduces the volume and thereby increases the velocity of the gas to its input level for ex iting through exhaust port 32 where it is discharged as decontaminated gas 34.

It should be noted that the blower may be placed anywhere in the circulating system and need not be inte gral with the precipitating system as shown, said disclosure being merely for convenience of the present description. Further, the preeipitator chamber 16 may be manufactured separate from or as an item of the complete unit illustrated in FIG. 1 without departing from the scope of the present invention.

The unique configuration of the preeipitator housing and the electrode plates housed therein is illustrated particularly in FIGS. 2 and 6. This configuration permits continuous radial cleaning of a portion of the collector plates while the remaining plates continue to function, continuously decontaminating the gaseous medium without interruption. The housing includes a preeipitator chamber 16, a cleaning chamber 18 and an indexing mechanism 17. The indexing mechanism periodically moves dirty or clogged collector plates into the cleaning chamber where the collector plates are scrubbed, dried and then returned to the gas stream.

The collector plates collectively form a rotatable drum 35 having hollow core 57. Primary support electrodes 60 extend radially outward from hub 56 and form support members defining a plurality of sector shaped cells 36-47, see FIG. 6. The primary electrodes 60 support the remainder of the electrode plates and provide a base-charged ground plate for each cell. Each electrode plate 5053 is formed by two walls a and 17' joined at apex c, the resulting dihedral angle being equal to the angular displacement between each pair of adjacent primary plates 60. The walls of successive plates decrease sequentially in length defining a graduated series of electrodes adapted to be mounted in each cell in the stacked, spaced, parallel arrange ment of FIG. 6, wherein their apices each fall on a com mon radius of the drum bisecting the sector defined by each pair of primary electrodes 60. The plates are maintained in proper spaced relationship, and parallel to one another by spacers 78 and/or 82, being secured within each cell by a pair of insulator retaining rings 58 extending about the periphery of drum 35. This ar rangement permits wide variation in the number and size of the collector plates without requiring substantial modification of the overall design. It should be understood the number of cells may be varied by changing the included angle between each pair of adjacent pri mary plates 60, and likewise the angle between walls a and b of each plate 50-53. Where the angular displace ment of each cell is 30 as illustrated, the drum contains twelve duplicate cells, and the included angle between walls a and b of each plate 50-53 is likewise 30.

Spacers 78 provide spacing between each plate 50 and a pair of adjacent electrodes 60. The spacers are of an insulating material such as glazed porcelain or the like, and maintain electrical isolation between primary electrodes 60 and plate 50, thus permitting plate 50 to carry a charge ofa polarity opposite the charge polarity of plates 60. The next plate in succession, plate Sl, is excited with the same charge as the primary plate by utilizing conducting spacers 82 which are integral with plate 51 and extend outward therefrom. The spacers are of a length equal to the distance between plate 51 and plates 60 and are disposed in contacting relationship therewith. Clearance openings 80 in plate 50 provide open, non-contacting passage for spacers 82 therethrough, thereby maintaining electrical isolation between adjacent plates. The clearance openings are suf ficient to preclude flashover or arcing between oppositely charged plates. Thus, conducting spacers 82 maintain correct spacing and electrical isolation of plates 50 and 51 while providing electrical communica tion between primary electrode plates 60 and plate 51. Plate 52 is likewise inserted inside the included angle between walls a and b of plate 51, conducting spacers 82 pass through clearance openings 80 of plate 51 and are disposed in contacting relationship with plate 50, thereby conducting the charge of plate 50 to plate 52. Plate 53 is inserted in a like manner. Thus, plates 60, 5l and 53 are maintained in electrical communication and bear an identical charge, for example a positive ground charge as illustrated in FIG. 6, and plates 50 and 52 are maintained at the opposite charge, here neg ative.

FIG. 9 diagrammatically illustrates the relationship between the various plates, the drum structure, and re- 3 .XUtHlbll port for the various plates nested in each cell. Retaining rings 58 are rigid y secured to edge of each primary electrode and extend about the periphery of drum 35. see FIG. 2. Each primary electrode 60 is of width h and is large relatiw to the remaining plates, each of width I1 This r-it-.urcs clearance and electrical isolation between retaining rings 58 and plates 5l)53. Each wall a and b of the various plates 50, 5] and 52 extend from the respective apices c to a common end line 63, and beyond edge 65 of each retaining ring 58, ensuring that the flowing gas is directed into the electrostatic field region between oppositely charged plates. End 6] of plate 53 extends beyond plates 50, 51 and 52 but does not contact rings 58. Springs 48 are inserted between rings 58 and end 61 to hold the entire assembly of plates 5053 in compression. generating the primary supportive force for holding the nested assembly of plates 5053 within the cell defined by an adjacent pair of primary electrodes 60.

To ensure that gas flowing in direction of arrow B passes only through an electrostatic field provided between oppositely charged plates. a barrier plate 62 is inserted between walls a and b of plate 53, and caps 84 are provided for the open ends of core 57, see FIG. 9. Caps 84 may be secured to hub 56. such as, by way of example means of a snug fit provided by plug 83.

The size and number of plates within each cell 36-47 may be varied, since by changing the included angle between each pair of primary plates 60 and likewise changing the angular displacement ofeach plate 50-53 the number of cells in precipitator drum 35 is easily varied. Only one set of insulating spacers 78 is required. since each plate in the graduated series of plates is spaced from a plate of like charge and is in isolated electrical communication therewith.

The housing enclosing drum 35 includes a precipitating chamber 16 having suitable openings for axially directing a gaseous medium through cells 3645 in communication therewith. and a cleaning chamber 18 comprising a washing compartment 74 and drying compartment 72 in radial communication with cells 47 and 46 respectively. The cells in communication with compartments 72 and 74 are closed to flow of the gaseous medium by a barrier. The unique configuration of the collecting plates permits radial introduction ofa cleaning fluid into each cell in chamber 74. Therefore, the solution is not directed along a path parallel to the surface of each plate, but strikes the plate at an acute angle, affecting a more efficient cleaning operation.

The cells in chamber 16 are charged or activated. alternate plates therein having like charges and adjacent plates having opposite charges as illustrated in FIG. 6, for attracting and collecting the charged particles from the gas circulating therethrough in a manner typical of two-stage electrostatic precipitator units. Cells 46 and 47 are deactivated and-cleaned during this period.

When two cells are in the deactivated position. pneumatic seal 64, see particularly FIG. 4, is inflated to effectively isolate the deactivated cells from one another and from the remainder of the other cells of the system. During this period cell 47 is sprayed via nozzle 76 with a suitable cleaning solution supplied under pressure through tube 24, washing the plates clean, the cleaning solution carrying the collected particles into washing compartment 74 and draining therefrom through drain 22 from which the solution may be disposed of or recycled. It should be understood other cleaning media could be introduced into chamber 74, as well. Walls 66 and 67 engage seal 64 to thereby completely enclose the washing compartment 74, where the contaminants are collected in a container substantially isolated from the precipitator chamber 16. Simultaneously therewith, cell 46 is dried in drying compartment 72. Blower 70 distributes not air as other drying media through tube 20 and nozzle 71 into the suitably vented drying compartment, drying all traces of the cleaning media from the plates of the cell. after which the dried cell is ready for return to the operating portion of the cycle. Where desired. it is possible to intermix an oil or similar dielectric fluid with the drying air of compartment 72, thereby coating each plate with a dielectric film, aiding in the particle collection process.

After cell 47 has been washed and cell 46 has been dried, pneumatic seal 64 is deflated as illustrated in FIG. 5, allowing drum 35 to be indexed in the direction of arrow A. advancing cell 47 into drying compartment 72, and returning cell 46 to an operative position, in chamber 16, while advancing cell 36 into compartment 74. Seal 64 is reinflated, again sealing the now acti vated cells 37-46 from the now deactivated cells 36 and 47, and the cycle is repeated. Since drum 35 always indexes in the same direction, for example clockwise as indicated by arrow A, the cleanest cell is always removed from drying compartment 72 and returned to an operative position while the dirtiest cell, having been in operation for the longest duration is the first cell to enter cleaning compartment 74.

It should be understood that the indexing movement is dictated by the number of cells contained in a particular precipitator drum. This indexing can be achieved by a suitable mechanism denoted generally by the numeral 17. For example, uniformly satisfactory results have been obtained by utilizing an indexing motor controlled by the timer circuit illustrated in FlG. 8, advancing the drum 30 at the end of each timed interval. The indexing control could also be designed to respond to cell condition by measuring the resistance the system encounters in charging the plates. When the resistance reaches a certain level due to particle collection and build-up, the indexing mechanism is activated to index a cell into the cleaning chamber.

The particular configuration of the pneumatic seal 64 as utilized in the preferred embodiment is illustrated in detail in FIGS. 3, 4 and 5, and provides means for isolating the cells to be cleaned from the cells maintained in an operating mode. As illustrated in FIG. 3, a pneumatic, expandible tube 64 extends about the entire periphery of one primary electrode 60, i.e., from hub 56 along one side edge of electrode 60 to a first insulator rim 58, across front edge 59, and over the other insulator rim 58, back along the other side edge of plate 60 to hub 56, and from there across hub 56 to another, adjacent electrode 60, about the periphery thereof. again across hub 56 and about a third electrode 60.

The pneumatic seal is normally in a deflated condition as shown in FIG. 5, allowing drum 35 to index to position. Once a cell has entered cleaning compartment 74 the indexing mechanism stops, the cell is deactivated. and seal 64 is inflated by supplying air or other fluid media under pressure. thereby forming an effective fluid and gas tight seal around the periphery of each deactivated cell. The cleaning cycle and drying cvcle i r orme as described, after which the seal is deflated by exhausting the contents therefrom after "which dtni is advanced, in the prelpn', example, through thirty degrees. The seal is then einflated and the cycle repeated.

Exemplary electric circuitry for charging the precipitator unit is diagrammatically illustrated in FIG. 7. The drum 35 provides the ground surface of the precipitator and usually includes a hub 56 and support electrodes 60 of unitary construction. A single power source 91 provides power for both ionizing chamber 14 and drum 35. Transformer 88, attached to leads 112 and 114, is utilized to obtain the proper voltage levels for each section. A typical full wave rectifier 122 is at tached to lead from transformer 88 and to ground lead to convert the alternating current from ac. source 91 to direct current for charging the various ionizing and collecting electrodes. Positive lead 92, con nected to one side of the rectifier via lead 95, is coupled to hub 56in any suitable manner for providing an electrical link to primary electrodes 60 and like charged electrode plates 51 and 53. The remaining plates are charged by use of hub 56 as a commutator having a plurality of insulated conducting pads spaced thereabout, one for each cell 3647. Each pad is in electrical communication with one plate 50 and associated like charged plates 52 and 54 via lead 101, an insulating liner isolating each pad from hub 56. Brush holder ring 99 extends arcuately about the commutator hub and is in contacting relationship with each pad 100 for cells in operative position, here cells 36-45. Lead 93, from the negative side of rectifier 122, supplies the necessary electrical link and is attached to ring 99 in any suitable manner. Therefore, each operative cell 36-45 has positive lead 92 and negative lead 93 in electrical communication therewith, negatively charging electrodes 50 and 52 and positively charging electrodes 60, 51 and 53, generating an electrostatic field in the spaces therebetween for collecting ionized particles passing therethrough. Cells 46 and 47 are deactivated, since only lead 92 is coupled thereto, the commutator ring 99 not being in communication with either cell, thereby providing an OPEN switch or OPEN circuit condition.

Thus, each cell in an operative position is activated, and each cell in an inoperative position deactivated. As drum 35 rotates in the direction of arrow A, cell 36 will be deactivated when pad 100 associated therewith moves beyond commutator ring 99. Likewise, cell 46 will be transformed from a deactivated state to an activated state as soon as the pad associated therewith comes in contact with ring 99.

Negative lead 90 provides electrical communication between transformer 88 and charging electrodes 98 of the ionizing chamber 15. Grounded plates 96 are supplied by positive lead 89, setting up an electric field for charging the particles moving with the gas flowing through ionizing chamber 14. The particles are then attracted and collected by collecting plates bearing an opposite charge as the gas flows through precipitator chamber 16. Generally, the field set up in the ionizing section is substantially greater than that in the precipitator, exemplary charging potentials being 15,000 volts and 6,000 volts respectively.

Where desired, a switch 116 may be inserted in one of the leads from source 91, for selectively connecting and disconnecting the source and associated electrical circuitry. Further, for safety, the circuit may be com monly grounded at 94.

A suitable circuit for controlling the sequence of operation is illustrated in FIG. 8. A Time Sequence Chart is there included, showing the condition of each circuit element at each step of one entire cycle. Power to leads 200 and 201 may be provided from any d.c. power source, including but not limited to independent source 118 as shown. Leads 204, 210, 214, 218, 224, 228, 232, 236, 240, 244, 250 and 254 are always connected with lead 201 and are continuously LlVE or in a conducting state.

Each contact has two states. OPEN and CLOSED, and when CLOSED, completes an electrical link thereacross. Further, each contact has a normal state and a biased state, the normal state being the state of the contact when not activated. Each of the contacts illustrated in FIG. 8 are shown in the normal or inactivated state. The contacts are controlled either by electrical elements, for example control relays, or by mechanical elements, for example micro-switches or limit switches. The state of each contact for each cycle stage is illus trated in the accompanying Sequence Chart as C, CLOSED, or 0, OPEN.

Leads 202 and 204, connected to leads 200 and 201, respectively, are attached to opposite sides of control relay CR2. The control relay is ON or in an operating state when both leads 202 and 204 are LIVE, i.e., a closed circuit exists between lead 200 and lead 202. When switch 116 of FIG. 7 is closed and the electrical circuit therein is activated by source 91, both sides of transformer 88 are LIVE and control relay CR1 inserted in lead 95 is ON or activated. This shifts contacts lCRl from the normal OPEN state to the biased CLOSED state, and since contact 1T1 is normally CLOSED, relay CR2 is switched ON. This CLOSES contact 1CR2 in bypass loop 206, bypassing contact 1CR1. Therefore, in the event relay CR] is switched OFF during the operation of a sequential cycle, one cycle will continue to completion before the circuit of FIG. 8 is rendered inoperative.

Contacts 2CR2 and 3CR2 are associated with a solenoid operated fill valve for supplying air or like fluid to pneumatic seal 64. When solenoid T is ON, and solenoid F is OFF, the valve is switched ON, and air enters and inflates the seal. When the state of each solenoid is reversed, no air will enter the seal. Therefore, air cn ters the seal only when contacts 2CR2 and 3CR2 are in the normal (as illustrated) state. Since CR2 is ON, both contacts 2CR2 and 3CR2 are transformed to the biased state, breaking lead 208 and closing lead 212, turning the fill valve OFF.

Solenoids O and C are associated with a solenoid operated emptying valve for controlling the flow of air from seal 64. Therefore, the empty and fill valves must work in conjunction with one another and are controlled by the same control relay, here relay CR2. When solenoid O is ON and solenoid C is OFF the empty valve is OPEN and any air in seal 64 is exhausted therefrom, deflating the seal. When solenoid O is OFF and solenoid C is ON, the valve is SHUT, retaining air in seal 64, allowing the seal to inflate. Thus, when the fill valve is ON and the empty valve is SHUT the seal is inflated, and conversely when the fill valve is OFF and the empty valve is OPEN the seal is deflated. The empty valve is controlled by contacts 4CR2 and 5CR2, shown in the normal state. Since relay CR2 is ON,

contacts 4CR2 and SCRZ are transformed to the biased state, completing lead 216 and breaking lead 220, switching solenoid ON and solenoid C OFF, OPEN ING the empty valve and deflating seal 64.

A micro-switch MSI is associated with seal 64, see FIGS. 4 and 5. Arm I thereofindicates when the seal is inflated or deflated, the arm tripping the switch when the seal is inflated as illustrated in FIG. 4. The seal being presently in a deflated condition, micro-switch MSI is not tripped, and all contacts associated therewith remain in a normal state. Therefore contact IMSI remains OPEN, breaking lead 226 and maintaining control relay CR3 in an OFF condition. Thus the contacts associated with relay CR3 are presently in their normal state.

Solenoid L controls lock arm I06, see FIG. 7. When precipitator drum 35 is in proper position, two cells being inoperative and in cleaning chamber I8 comprising washing compartment 74 and drying compartment 72, lock arm I06 is extended into one of seats 104 provided for each cell in hub 56, locking the wheel in position. Since relay CR3 is presently OFF, contact 2CR3 remains OPEN, breaking lead 230, and maintaining lock solenoid L in an OFF condition,

When the cells are not in proper position, they must be rotated in direction of arrow A, It is desirable that only one cell move through the cleaning station each time drum 35 is rotated, therefore an indexing motor M is controlled by microswitch MS2 indicating the position of each cell as it enters the cleaning chamber. Arm I10 extends from micro-switch MS2 and is tripped by a pad I00 when a cell is in proper position for the cleaning and drying operation. As illustrated in FIGS. 7 and 8, cell 47 is not in proper position, switch MSI is not tripped, and the contacts associated there with are in the normal state. Therefore, contact 2MS2 remains CLOSED, and since relay CR3 is OFF, contact 3CR3 is CLOSED, completing lead 234, switching motor M ON, indexing drum 35. This condition is illustrated in the Index column of the Sequence Chart of FIG. 8.

When motor M rotates drum 35 into position, switch M82 is tripped, OPENING contact 2MS2 and turning motor M OFF by breaking lead 234. The system is now in the Stop stage, as illustrated in the Sequence Chart. As motor M stops, switch M82 is tripped, CLOSING contact 3MS2 and completing lead 242 thereby activating timer Tl, transforming the system to the Timed In state of the Sequence Chart. Timer TI remains ON for a fixed, predetermined period of time, then switches OFF without respect to the state of contact of 3MS2. When timer T1 is ON, contacts lTI are OPENED switching relay CR2 OFF, reversing state of each valve solenoid T, F, O and C, filling and inflating seal 64, and tripping arm 115 of switch MS]. Contact IMSI CLOSES completing lead 226 and switching relay CR3 ON to activate lock solenoid L by CLOSING contact 2CR3 and completing lead 230, extending arm 106 into seat 104. Tab 107 of arm I06 trips arm I08 of switch MS3, OPENING contact IMS3 in lead 246.

Contacts 2T1 are CLOSED, completing lead 238 and activating time delay circuit TDI. The time delay circuit remains OFF for a fixed period of time after being activated, switches ON momentarily, and returns to the deactivated state. Contacts 3T1 and 4T1 are also CLOSED by timer TI, completing leads 248 and 252 and activating wash cycle W and dry cycle D.

When timer TI times out and automatically switches OFF the system is transformed to the Time Out state of the Sequence Chart. Contacts 2T1, 3T1 and 4T1 return to normal, deactivating the time delay circuit and the wash and dry cycles. Contact lTI returns to normal, or CLOSED, activating relay CR2, reversing valve solenoids T, F, O and C, deflating seal 64, returning arm II5 of switch MS] to the unbiased state, switching contact IMSI to OPEN, breaking lead 226 and switching CR3 OFF. Contact 2CR3 is OPENED, deactivating lock solenoid L and retracting arm I06 from seat 104. Switch MS3 is returned to the unbiased state, returning contact IMS3 to the normal, CLOSED position, completing lead 246 and resetting timer Tl.

When contact 2T1 is OPENEd by switching timer TI OFF, time delay circuit TDI remains dormant momentarily, then is activated for a short duration before re turning to the normal condition, transforming the system to the Time Delay In stage of the Sequence Chart. Contact ITDI is CLOSED, completing bypass lead 235, and since contact 3CR3 is in the normal CLOSED state, lead 234 is completed, switching motor M ON, rotating drum 35. Contact ITDl OPENS after a short duration, but motion of drum 35 moves pad beyond arm IIO of switch MS2, returning arm I10 to normal, CLOSING contact 2MS2, allowing motor M to continue, returning the system to the Index State from where the cycle is repeated.

It should be understood the electrical circuitry herein described is merely illustrative and is not intended to limit the scope of the invention. While certain detail with respect to electrical-mechanical interconnections has not been specifically illustrated, such details will be readily apparent to the skilled electrician and may be accomplished in any manner well known to those who are conversant with electrical-mechanical control sys terns,

Further, it should be understood that the present invention is adapted for use in a vertical flow system as well as in the horizontal system as illustrated. While particular embodiments of the invention are described in detail, such are not intended to limit the scope and spirit of the invention as deflned by the appended claims, but serve only as an illustration of the various features and objects thereof.

What is claimed is:

I. An electrostatic precipitator comprising a housing including a precipitator chamber and a cleaning chamber outwardly therefrom; a drum rotatably mounted in the housing and means physically isolating the precipitator chamber from the cleaning chamber the drum subdivided into a plurality of duplicate precipitating cells certain of which are in selective communication with the precipitator chamber and certain others of which are in selective communication with the cleaning chamber; means imparting an electrostatic field across those cells in communication with said precipitator chamber; an inlet port and an outlet port in said precipitation chamber for directing a fluid medium through said precipitator chamber and axially of said drum; means in the cleaning chamber for introducing a cleaning media into said cleaning chamber and radially of said drum; and means for rotating said drum relative to said housing in step-by-step manner to selectively index and advance the precipitating cells into and out of communication with one or the other of said chambers.

2. An electrostatic precipitator as called for in claim 1, which includes a mechanical pre-filter for removing particulate matter of a predetermined size from said fluid medium, and an ionizing chamber for exciting particulate matter remaining in said fluid medium with a common electrical charge, said prefilter and ionizing chamber disposed in advance of and in open communication with the housing.

3. An electrostatic precipitator as called for in claim 1, which includes an after-filter disposed to the rear of and in open communication with the housing for removing particulate matter remaining in the fluid medium leaving the housing.

4. An electrostatic precipitator as called for in claim 1, which includes means for inducing a flow of fluid medium through the precipitator chamber and axially of the drum.

5. An electrostatic precipitator as called for in claim 1, which includes an inflatable seal carried by the housing and adapted to selectively engage the periphery of the drum for isolating the precipitating cells which are in communication with said cleaning chamber from the precipitating chamber.

6. An electrostatic precipitator as called for in claim 5, which includes means for sequentially:

a. deflating the seal to terminate the sealing relationship between certain of the cells and an inner wall of the housing;

b. deactivating the electrostatic field across those cells in communication with the precipitator chamber;

c. rotating the drum to advance that cell of the precipitator chamber adjacent the cleaning chamber into the cleaning chamber while simultaneously advancing that cell of the cleaning chamber adjacent the precipitator chamber into the precipitator chamber;

cl. inflating the seal to effect a sealing relationship between certain other of the cells and an inner wall of the housing;

e. reactivating an electrostatic field across the cells in communication with the precipitator chamber; and

f. introducing a cleaning media into the cells in communication with the cleaning chamber.

7. An electrostatic precipitator as called for in claim 6, including means for introducing a drying media into the cells in said cleaning chamber prior to the advance ment thereof into said precipitator chamber.

8. An electrostatic precipitator as called for in claim I, wherein each cell comprises a series of electrodes disposed in nested, spaced, parallel relationship the individual electrodes comprising a pair of intersecting plates which diverge from respective apices located at spaced intervals along a common radius of the drum.

9. An electrostatic precipitator as called for in claim 8, wherein the plates of one electrode of each cell di verge from an apex located at the center of said drum. defining a sector thereof.

10. An electrostatic precipitator as called for in claim 9, which includes an insulating-spacer interposed between said sector-defining electrode and the other electrodes of each cell; and a plurality of conductingspacers disposed between the plates of the alternate electrodes of each cell, maintaining the plates of said alternate electrodes in proper spaced relationship and in electrical communication with one another.

11. An electrostatic precipitator as called for in claim 10, which includes a retaining ring extending about the periphery of the drum and rigidly secured to each of said sector-defining electrodes; and a flexible spacer interposed between said retaining ring and the other electrodes of each cell maintaining said electrodes in compression against said insulating spacer.

12. An electrostatic precipitator as called for in claim 10, wherein adjacent electrodes of each cell are adapted to be excited with electrical charges of opposite polarity.

13. An electrostatic precipitator as called for in claim 1, wherein said cleaning chamber includes a washing compartment and a drying compartment physically isolated from one another.

14. An electrostatic precipitator as called for in claim 13, which includes means for introducing drying media radially of said drum into cells in communication with said drying compartment.

15. An electrostatic precipitator as called for in claim 14, which includes means for introducing a dielectric fluid into said drying media.

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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4277258 *Dec 7, 1978Jul 7, 1981F. L. Smidth & Co.Electrostatic precipitator and discharge electrode therefor
US4846856 *Apr 25, 1988Jul 11, 1989Burger Thomas FCirculating air scrubber
US6398848Apr 26, 1999Jun 4, 2002American Electric Power ServiceChanging momentum of exhaust gas flow by drastically altering diameter of feed stream or deenergizing one or more static electric charging fields of electrostatic precipitator; fractionating coal exhaust gas
US6447580Jul 26, 2001Sep 10, 2002R. F. RidgewayElectrostatic precipitator
US7332019 *Aug 17, 2005Feb 19, 2008American Standard International Inc.Air filtration system
US7351274 *Aug 17, 2005Apr 1, 2008American Standard International Inc.Air filtration system control
US8414687 *Sep 23, 2010Apr 9, 2013Chevron U.S.A. Inc.Method to control particulate matter emissions
US20120073436 *Sep 23, 2010Mar 29, 2012Chevron U.S.A., Inc.Method to control particulate matter emissions
U.S. Classification96/31, 55/290, 96/57
International ClassificationB03C3/34, B03C3/74
Cooperative ClassificationB03C3/74
European ClassificationB03C3/74