US2588364A - Electrostatic precipitator - Google Patents

Description

March 11, 1952 Filed May 16, 1947 E. DEGIORGIQ ELECTROSTATIC'PRECIPITATOR 8 Sheets-Sheet l TIER A INVENTOR. EDI/AFB UIGIORGI.

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March 11, 1952 E. DEGIORGI 2,588,364

ELECTROSTATIC PRECIPITATOR Filed May 1947 8 Sheets-Sheet 2 Jcction fl Jectzbn B I 5 INVENTOR. 5000/90 0.2510261.

March 11, 1952 E. DEGIORGI ELECTROSTATIC PRECIPITATOR 8 Sheets-Sheet 3 Filed May 16, 1947 9- INVENTOR.

EDUHRO DiGIO/QG 4 TTOENEX' March 11, 1952 E. DEGIORGI 2,583,354

ELECTROSTATIC PRECIPITATOR Filed May 16, 1947 s Sheets-Sheet 5 92 Pm L wgg F g JNVEN TOR. ECU/7RD DEGIOEGI.

March 1952 E. DEGIQRGI ELECTROSTATIC PRECIPITATOR 8 Sheets-Sheet 6 Filed May 1947 N VEN roe, 504/990 2612.

/ ax l bis a 7' TO v x March 11, 1952 E. DEGIORGI ELECTROSTATIC PRECIPITATOR 8 Sheets-Sheet 7 Filed May 16, 1947 1 ms M NI m ND .w 1 e m r 5 5 M mm .w\ Q NH l I I I I I I I I I I I I l I I l I I I I I I I I l l I I I l l l l II WHIH H.HIII||||1|I|I|HH| |rll|||| llllll IIIIIIII lllll llllll l I l I r I lw m Patented Mar. 11, 1952.

ELECTROSTATIC PRECIPITATOR Eduard Degiorgi, Zurich, Switzerland, assignor to Koppers Company, Inc., Pittsburgh, Pa., a cor-' poration of Delaware Application May 16, 1947, Serial No. 748,482

19Claims. 1

This invention relates to electrostatic precipitators and is particularly directed to apparatus for electrostatically precipitating solid particles, such as dust, fume, fly ash and like particles hereinafter collectively referred to as dust, from gases at high temperatures.

The invention has for its objects to provide improved means for electrostatically removing dust from gases at high temperatures; to provide improved collecting electrodes for electrostatic'precipitators; to provide improved means for dislodgingaccumulated dust from collecting electrodes; to provide improved means for withdrawing dislodged dust from the gas stream; to minimize redispersion Iof dislodged dust; to minimize overall construction and maintenance cost; to avoid the disadvantages of the prior art and to obtain advantages as will bepointed out or as will become apparent as the description proceeds. Further objects will appear in the description of the invention.

A problem which has long confronted those skilled in the art of removing dust from high temperature gases by means of electrical precipitators and, heretofore, has not been satisfactorily solved, is that of removing the dust which accumulates on the collecting electrode. This problem is particularly acute where the dust is light and fluffy, such as, fly ash, which is carried in flue gas from boilers and the like. Thepresa ent invention is primarily directed to the solution of this problem.

It has been customary in the past to provide means for rapping the collecting electrodes to dislodge the 'dust particles which have accumu lated on them. It was difiicult, however, to prevent redispersionof the dust in the gas stream.

-It was necessary, therefore, that the precipitators be undesirably smaller that the flow of gas be interrupted during the rapping operation.

In order to overcome these difficulties it has been proposed, as set forth in U. S. Patents to locate the receiving means very close together thereby increasing the cost of construction and maintenance or to make the unit undesirably high in order to reduce the dust content of the gas stream to the desired low level. In these and other respects such apparatus failed to achieve the desired obj ectives.

The present invention comprises a novel and advantageous construction and arrangement, particularly with reference to the collecting electrodes, whereby the above'mentioned objectives may be accomplished and the disadvantages of the prior art avoided. The invention may be best understood by reference to the accompanying drawing in which:

Figure 1 is a view looking in the direction of gas flow taken partly as a transverse section, section A beingtaken along line IA- IA, Figure 2 and section B being taken along IB-IB, Figure 2;

Figure 2 is a longitudinal section on planes parallel to the gas now, section A being taken along IIAIIA, Figure 3, and section B bein taken along I IBIIB, Figure 3;

Figure 3 is a detailed view of part of Figure 1 taken in section along line III--III of Figure 5;

Figure 4 is a detailed view-of a like part of Figure 1 taken in section along line IV--IV, Figure 5;

Figure 5 is a detailed view taken along V-V, Figure 3;

Figure 6 is a detailed view of across beam of Figure 2 taken along line VI--VI, Figure 3;

Figure '7 is a section taken along line VIIVII,

Figure 4;

Figure 8 is a cross-section of the horizontal beam shown in Figure 7;

Figure!) is an isometric view of a similar beam;

Figure 10 is a side elevation view of a collecting electrode plate;

Figure 11 is an end elevation of Figure 10;

Figure 12 is a cross section view of Figure 10;

Figure 13 is a detail of a holding plate seen in Figure 10 Figure 14 is a section taken along line XIV-XIV, Figure 13 Figure 15 is a detail of the lifting bar showing one of the pins displaced;

Figure 16 is a detailed View of the upper left hand portion of Figure 2, and

Figures 17 and 18 are detailed views of the cam lifting mechanism.

Referringnow to the drawing and more particularly to the Figures 1 and 2, the precipitator is shown in transverse and longitudinal sections. The precipitator. GIGIIlBIIES WhlCh will be more particularly described, are enclosed in a horizontally extending housing 2 of generally rectangular transverse and longitudinal sections. This casing constitutes a part of a flue or conduit for conducting dust-laden gases to and from the precipitator elements. The open ends of the housing 2 are united by means of suitable joint 4 with the inlet and outlet flues or conduits B and 8. The housing 2 and precipitator elements therein are supported by a framework of steel beams comprising upright steel beams l0, transverse beams l2 and longitudinal beams M and longitudinal cross-beams I6. This framework is suitably lined with steel plates or sheets as required to form the desired closure (housing 2). Details of the construction of the framework and housing are not shown because it is within the skill of the art to provide a suitable supporting structure and housing for the precipitator elements of the invention.

The precipitator elements are arranged in two or more tiers. Three such tiers, designated as A, B and C are shown in the drawing as more particularly seen in Figure 1. In each tier there is provided a plurality of parallel precipitating units 18 each of which comprises spaced parallel collecting electrodes 20 extending longitudinally of the housing 2 with intermediate discharge electrode assemblies 22 operatively associated therewith. Each pair of such collecting electrodes, with the exception of those in the top tier is provided with a cover member 24 which is convex in cross-section; i. e. shaped like an inverted U, V or semicircle. A like member 26 is located at the bottom of the precipitating units it! of the bottom tier A. These members act as tops and bottoms to the precipitating units making them into parallelly disposed longitudinal channels 28 through which the incoming dust laden gas passes in travelling from the inlet flue 6 to the outlet flue 8.

As best seen in Figure 1 it will be observed that each of the precipitator units is shaped like an inverted U, or shall we say, like a hair-pin, and are disposed side by side, but spaced suificiently to provide a narrow channel 36 between adjacent collecting electrodes. The collecting electrodes 28 extend downwardly into the V formed by each pair of units l3 and are spaced sufficiently from the top members 24 to provide horizontal slot-like passageways 32 leading from the channels 28 of the precipitating units 18 into the narrow passages 30 between them. As dust is dislodged from-the collecting electrodes 28 it tends to fall down along the surface of said electrodes to the bottom of each tier where it is defiectedthrough the slot like passages 32 by the sloping sides of the convex cover members 24 into the narrow-channels 3!! through which it falls into one or more hoppers 34 at the bottom of the structure.

In order to simplify construction and operation of large capacity precipitators two or more units such as described above may be included in a single housing as illustrated by section A and B of Figure 1. It will be observed that in these figures the detail of the precipitator unit [8 have not been completed throughout since it is purely repetitious. It should be noted, however, that adjacent the outside walls 36 of the housing 2 the passageways are defined by the outside walls 36 and the collecting electrode 20 of the adjacent precipitating unit l8. Between the sec- (not shown) limiting the Width of the channel.

may be provided.

The collecting electrodes 20 of each tier are supported on horizontal supporting beams 38 and 39 parallelly disposed with reference one to the other and extending longitudinally of the housing 2. The ends of these beams are supported by the transverse beams 52. In order to simplify construction and operation of large size precipitators the precipitating units may be divided longitudinally into two or more sections as illustrated by sections A and B of Figure 2. In such case the inner ends of the supporting beams 33 are supported by cross-beams so located between said sections. These supporting beams are con structed so as to provide rigid immobile supports for the collecting electrodes.

The particular construction of the supporting beams 36 is best seen in Figures 8 and 9. Each such beam comprises parallel side plates 42, each provided at the top with a unitary outwardly flaring plate a l. It will be understood, of course, that where the supporting beam is adjacent the side wall of the housing 2 only one such outwardly flaring plate 44 will be provided as best shown in Figure 9. At each end there is provided a tubular section lit which is formed as a unitary structure with the side plates 52. These tubular supporting sections extend from the collecting electrode 29 t0 the transverse beams l2 and cross-beams 49.

At spaced intervals along the length of the sup porting beams are provided vertical cross-plates 48. These plates extend into said supporting beams between side plates t2 and have outwardly flaring shoulders 5ft resting on the outwardly flaring plates 4d and conforming to the slope thereof as best seen in Figure 8. These plates are welded or otherwise united with contiguous portions of supporting beam to form a unitary structure. At the inner end of the tubular portion 45 of these beams there is provided an end plate 52 which has a shape similar to that of the cross-plates 68 but preferably has longer shoulders 54, preferably substantially of the same length as the outwardly flaring side 44. These plates are welded or otherwise united to the contiguous parts of the supporting beam to form a unitary rigid structure.

The cross-plates 48 are each provided with a verticalslot 56 aligned with each side plate lf. These vertical slots are adapted to receive the collecting electrodes as will be more particularly described. In the bottom of each slot 56 there is welded or otherwise secured an anvil or striking bar which may be a separate member 57 for each cross-plate as shown in Figure 9 or a continuous bar 58 as shown in Figures 5 and 6.

The supporting beams 39 are required to give lateral support only and do not need the supporting cross-plates and striking bars required for beams 38. outwardly flaring plates as. It is sufficient, therefore, for them to be constructed simply of the parallel plates d2.

The arrangement of the above described supporting beams and the disposition of the various elements of the precipitating units It with respect thereto are best illustrated in Figures 3 and 4, the details of which may be best understood after the collecting electrodes 28 have been described in further detail. It is sufiicient to note here that the outwardly flaring side plates 44 of the supporting beams 38 together with the cover plates (it constitute the convex cover member 2 t previously described.

As best seen Figures 2, 6 and 7 the collect Likewise, they do not need the ing electrodes 20 of each tier are made up of a plurality of vertical section plates 62 arranged in a common vertical plane with their vertical edges in juxtaposition. Each of plates 62 have upstanding ribs 64 along their vertical edges which function to reinforce the section plate and to impede the flow of gas along the surface of the collecting electrodes as will be described in greater detail later. They also provide an overlapping joint which permits each section plate to move vertically independently of the others. Thus, there is provided an articulated collecting electrode of which the section plates 52 constitute the articles and the ribs 64 the joints.

The construction of the section plates 52 is best shown in Figures through 14. Each is made of an elongated flat plate provided along one edge with an inwardly turned rib 66 and along the other edge with the outwardly turned reinforcing rib 64 comprising an outwardly turned portion i0 and an inwardly turned portion l2. It is noted that the inwardly turned portion 12 terminates substantially at the plane of the outer surface of the plate 52. The two reinforcing ribs 64 and Gil extend substantially the full length of the plate 62 and impart rigidity thereto. The inturned rib '58 preferably terminates short of the upper edge M of the plate 62 to facilitate insertion and removal of the plate as it will be presently described. The outstanding rib 64 similarly may be cut away both at the top and the bottom as best shown at it and 18 in Figures 10 and 5 to provide clearance with respect to adjacent parts and to facilitate insertion and removal.

To the back of plate '52 near the top 14 there is welded on or otherwise fastened a small plate 8|] which is embossed at 82 and slotted at 84 so as to form a slot with undercut channels 85 between the embossed portion 82 and the plate 62, as best shown in Figure 14. The undercut slot 84 is open at the bottom and closed at the upper end (Figure 13) for purposes which will presently be described. At the bottom of plate 62 a sheet of steel 88 bent on itself and about plate 62 is welded thereto to provide a reinforced striking surface. This reinforcing plate extends substantially the width of plate 62 and in assembled position rests on the anvils or striking bar 58 as best seen in Figures 3 and 4.

The above described section plates are assembled in the precipitator with bottom edges resting in the slots 56 of cross-plates 48 of supporting beams 38 as best seen in Figures 3 and 4 and with top edges resting against the side plates 42 of the next higher supporting beam. The section plates are thus arranged side by side in a common plane as illustrated in Figure 7 with the upstanding joint or rib 5Q overlapping the juxtaposed edge or side of the adjacent plate. Suitable means, a suitable modification of which will be described presently, is provided to hold the plates in contact with the side plates 42 of the supporting beams 38. Thus supported, the section plates are adapted for a limited vertical movement and, by means of a suitable mechanism as will presently be described, the section plates may be raised off of the anvils or striking bars 58 and dropped thereon at suitable intervals and in suitable order to dislodge the dust it which accumulates on the collecting electrodes -20 in operation of the precipitator.

- the gas stream. These strips are provided with inturned edges 94 and 98 to impart rigidity thereto.

type of precipitator involved the flow of gas is horizontal; i. e., the gas flows longitudinally through the housing 2, and that any dust particles dislodged from the surface of the collecting electrodes and redispersed into the gas stream tend to be carried along with the gas stream to a point farther along the particular channel through which the gas is passing. Now, by raising the section plates 62 and dropping them on the striking bars 58 a shock is imparted to the collecting electrodes which has substantially no normal component. This means that the dust particles are removed or dislodged from the surface of the collecting electrodes by a shearing action, the impetus of which tends to project the dust particles on their downward path. If a rapping means were used which imgas stream to a point farther along in the channel 28, it is vitally important.

Now, if a plate is dropped on its edge on an anvil, the shock imparted thereto is dissipated in several ways among which are the bounce or rebound of the plate and the lateral vibrations set up therein. In order to minimize the latter, which as has been fully explained, are undesirable in the particular apparatus here involved, I have provided the vertical reinforcing ribs 84 and 68, previously described, which impart a degree of rigidity to the section plate which tends to in crease the rebound, and hence the shearing action and to dampen lateral vibration which tends to impel the dust particles into the gas stream. Furthermore, the outstanding ribs 64 tend to impede the flow of gas along the surface of: the collecting electrodes so that any redispersed dust has less tendency to migrate longitudinally in the precipitator. The net effect of the various features above described is this: when the section plates 62 are raised and dropped on the striking bars 58, the dust particles are sheared from the surface of the collectin electrodes 20 and given an impetus downwardly along the surface thereof. These particles therefore tend to drop straight down along the surface of the collecting electrodes without being redispersed into the gas stream. When they reach the bottom they fall onto the outwardly flared plates 44 of the supporting beams 38 and are deflected through the slot-like passages 32 into the narrow channels 30 whence they are conducted to the hoppers 34.

The mechanism for raising and lowering the section plate 62 comprises a cam actuated lifting bar'98 pivotally connected to each section plate 52 by means of the pins I08 projecting from the lifting bar 98 into the slot 84 of the plate 39 which is welded or otherwise fixed to the inner surface of the section plate 62 near the top thereof. The

pins I80 are provided with heads I02. The undercut slot 312 slips over the head H32 so that the head engages the embossed portions of the plate 82.

This arrangement constitutes the means above referred to for holdin the section plate 52 in position with the top edges against the side plates 42 of the supporting beam 38.

The head H32 of the pin suitably may be formed by machining an annular channel me on the pin. In such case the diameter of the pin will be substantially the width between the undercut channels 86 and the diameter of the neck me of the annular channel Hit will be substantially that of the slot 8-1. The pins I are journaled in holes I98 in the lifting bar as best illustrated in Figure 15. The pins may be welded in place if desired to form a unitary structure, but ordinarily where each end of the pin supports a section plate welding is not necessary. In fact, it is advantageous not to do so in view of the greater ease of replacing worn pins.

this purpose also to have the slot 56 equal in length to or longer than the slots 34. This facilitates inserting the section plate since it is easier in such case to effect engagement of the undercut slot 84 with head I02 of the pin.

The lifting bar S8 is raised and dropped by means of the cam IIIl which is driven by shaft [I2 journaled in framework HQ. The cam is embraced by a stirrup I I6 slotted at I I 8 to permit it to reciprocate with respect to the shaft I I2. A

cam rider i2il is adjustably mounted in the top of the stirrup. The bottom of the stirrup is fastened to a connecting rod i22 which passes into the housing tube through gland I24. The bottom of connecting rod I22 is pivotally connected to strap hangers I25 by means of the pins I28 and cotters I36. These strap hangers extend down through the narrow channels 30 and each lifting bar (there is one for each tier) is pivotally connected to the strap hangers by pins I32 and cotters I34.

In the form of the invention shown as seen in Figure 2 each end of the supporting bars 98 are supporte by the strap hangers I25. There is thus provided a pair of cam actuated strap hangers for each set of lifting bars. The two cams of each pair may be operated alternately or in unison; preferably, they are operated so that first one end of the lifting bar 98 and then the other 88. As illustrated in Figure 1, section B, the cams are mounted in staggered relation one to the other. In this manner the several electrodes are raised and dropped at different times. It isparticularly important that the raising and dropping of the pair of electrodes forming a single precipi- 8 tating unit should be alternated one with the other so that the general efilciency of the precipitator may be maintained at a high level. Similarly, and for the same purpose, the'cams operating section B of Figure 2 should alternate with those operating section A of that figure.

The heaviest load of dust deposited on the collecting electrodes will be on those section plates nearest the inlet. The cams of section B, Figure 2, therefore may be rotated more slowly than those of section A in order to provide a longer interval between rappings. Similarly and for the same purpose, the second row of cams of each section may be operated more slowly, if desired, than the first row.

The discharged electrodes proper consist of a plurality of vertically disposed parallel rods I36 generally angular (square for example) in crosssection to provide edges to promote discharge. The rods I36 are mounted in a tubular frame structure I38 consisting of top and bottom tubes I46 and I42, end tubes I 14 and M5, and intermediate cross-tubes MS. The frames are suspended midway between the collecting electrodes by hanger rods 5% to which they are removably fastened by suitable fastening means I52. Two such frames are provided for each tier.

The rods I36 are so spaced as to provide a plurality of precipitating electrodes for each section plate 82 (3 are shown) and they should be spaced closely enough together to obtain substantially uniform deposition of dust over the surface of the section plate with which they are associated in accordance with principles well known in this art. It will be observed that the spacing between each group of three, as seen in Figure 2, is slightly larger than the spacing between the individual rods of each group. This wider spacing is provided to accommodate the outstanding ribs 84. Thus, the end rod of each group of three is spaced further from the outstanding rib 64 than it is from the section plate proper, a distance sufficient to prevent arcing over.

The hanger rods 556 are suspended from transverse angles I54, fastened as shown at I56 to longitudinal supporting bars I58. These longitudinal supporting bars are in turn supported by the hanger rods its which are supported from the insulators i622. The bar E58 is fastened to the hanger rod I65 by a clevis I543. The other end of the hanger rod Iiiii is fastened to a spider I66 which rests on the top of a pipe 553 of ceramic or other rigid insulating material which, in turn, rests on the top of housing 2. A cover I'EI) is provided for pipe I68 and the whole insulator assembly is enclosed in a housing I12. The hanger rod rec extends through GE top of housing 2 through a pipe 53% of suficient diameter to prevent arcing. The bottom edge of said pipe is beaded also to prevent arcing.

The space between the uppermost tier of collecting electrodes and the top of the housing 2 is provided with a plurality of transverse partitions I36 extending entirely across the precipitator to prevent the dust laden gas from bypassing the precipitator unit. Each such partition is provided with apertures I'll? through which the longitudinal supporting bars E58 project. The edges of these apertures are beaded and spaced sufficiently from said bars to prevent arcing over. Each of the bars is provided with baliie plates idi of somewhat larger diameter than the apertures I '58 and disposed on each side of the partitions I'M; a distance sufficient to prevent arcing over. These baffle plates are beaded at their edges for this purpose too. .The apertures I18 coupled with the-baiileplates lfillconstitute a path of high resistance to gas flow so thatvery little, if any, gasis by-passed to the precipitator unit. I

, The discharge electrode rods. I36 are electrically connected throughtheir supporting structure, above describedqto thepositive pole of a suitable rectifier, not shown.

As best shownin Figures 1 and -2, rapping means is provided for ,dislodging dust from the discharge electrodes. ,This. meanscomprises a striker rod I82 of sufficientlength to span the space between the two longitudinal supporting bars I53 and to rest freely thereon. The.striker I82. is linked to fixed pivots, liltbylinks 188 so that the ,striker rod lfizoconveniently may be lifted ofi of thelongitudinal supportingbars I58 and dropped thereon. Sufiicient shock is thereby.

imparted to the discharge electrodes to dislodge what little dust accumulates on them.

Striker rod I52 is lifted by hook I83 which is pivotally connected to hanger rod 19!! at I92, which inturn is supported through the insulator I94 by a cable leiirunning over sheave I93 to a crank 2%. The hanger rod I98 passes through the top of housing 2 through a beaded pipe 282 of sufiicient size toprevent arcing and is enclosed by housing 2% upon which is mounted the sheave support 255 and the gland 2% through which cable I96 passes through the housing.

The hook its is pivotally connected to fixed pivots 2lfi by links 2l,2 .pivctally connected to the hook and is provided with .a projection 2M adapted to engage the striker rod I82 when in the positionshownv inFigureZ, section A. It is also provided with a rigid member 21% projecting in the same direction as the projection 2M.

Above the rigid member, 2H5 and in the path of its vertic al ,,movement is located a tripping pin 218 adapted to the position in one of several holes 22!) arranged in verticalalignment in a suitable support. 222. When the. crank 208 is rotated the hook I88 islifted, lifting with it the striker rod I82. When, it reaches the elevation shown in Figure 2, section B, the. rigidmember 2H5 will have engaged the pin Zilland caused the hook I85 to pivot sumciently to release the striker rod 132, and permit it tofall backon the horizontal bars 53. The bottom edge of the projection 2! 4 is bevelled as shown at 224 so that when the hook is again lowered it will automatically reengage the striker rod.

While I have described my invention with reference to a particularembodiment thereof, it will be understood that variation may be made therefrom without departing from the spirit and scope of the invention as described in the specification and set forth in the appended claims.

I claim: i

1. In an electrostatic precipitator the combination which comprises a substantially rectangular horizontally disposed conduit through which a stream of dust laden gas may bepassed horizontally, a plurality of longitudinally parallel vertically disposed partitions extending from the top to the bottom'ofsaid conduit dividing said conduit into a plurality of narrow longitudinal passages, said partitions including at the opposed faces thereof tiers ofcollecting electrodes, electrostatic discharge meansoperatively associated with said collecting electrodes and adapted to precipitate dust thereon, said partition bein hollow from at least the bottom of the uppermost of said tiers of collecting electrodes to the bottom of said 10 conduit with the bottom open to the exterior of said conduit, means for closing at least the front end of said hollowpartition thereby forming a vertical passage through which dust may drop to theexterior of said conduit without being dis turbed by the gas streamfiowing therein, rapping means for imparting shock to said collecting electrodesto dislodge, dust therefrom and deflecting means located between said tiers of collecting electrodes for deflecting dislodged dust into said hollow partition.-,

'2. In an electrostatic precipitator the combination whichcomprises parallel vertically disposed flat collecting electrodes, electrostatic discharge means between saidcollecting electrode and operativelyassociated therewith to precipitate dust thereon, conduit means for directing a horizontal flow of gas between said electrode means, said collecting electrodes including a plurality of flat plates arranged substantially in a common plane with theiredges in juxtaposition with the juxtaposed edgesturned out in opposite directions to providereinforced ribs and one of the turned out edges being turned back-in and terminating on the'surface of the. juxtaposed plate to provide a. reinforced. lap-joint said rib and joint being disposed inthe vertical position, rapping means for applying impact in the vertical plane thereof whereby the shock imparted thereto has no substantial normal component and the dust is dislodgedfro'm the plates by a shearing action and tends to drop'along-the surface of said plates between said joints, and receiving means for receiving the dislodged dust.

3. In an electrostatic precipitator the combination which comprises parallel vertically disposed fiat collecting electrodes, electrostatic discharge means between said collecting electrode and operatively associated therewith to precipitate dust thereon; conduit means for directing a horizontal flow of gas between said electrode means, said collecting electrodes including a plurality of fiat plates arranged substantially in a common plane with their edgesin juxtapositionwith the juxtaposed edges turned out in opposite directions to provide reinforced ribs and oneof the turned out edges beingturned back in and terminating on the surface ,of the luxtaposedplate .tuprovide a reinforced lap, joint, said rib and joint being disposed in the vertical, position,- said plates resting on and beingmoyable vertically with respect, t0 a fixedbasea lifting, bar, meansfor supportingsaid lifting. bar, inja horizontal position parallel to and ladjacentto the outside of each of said collectingelectrodes, means pivotally connectingsaid lirting bantoeach of. said plates adjacent thereto and;.means.forlifting and dropping-at least one end, of said lifting bar.

4.. In an electrpstaticpnecipitator the combina- 5. In an electrostatic precipitator the combination which comprises a series of collecting electrode assemblies including an immobile base, a vertical collecting portion resting on said base and movable vertically with respect thereto, and electrostatic discharge means operatively associated with said vertical collecting portion; each of said vertical collecting portions being provided with lifting means having disengaging means operative when said vertical collecting portion is lifted a predetermined amount to allow said vertical collecting portion to drop back onto said immobile base and said disengaging means being operatively staggered in said series whereby to avoid dropping of said vertical collecting portions in unison; and dust receiving means located at the bottom of and in line with each of said vertical collecting portion whereby dust dislodged therefrom falls into said receiving means.

6. In an electrostatic precipitator the combination which comprises a series of collecting electrode assemblies including an immobile base and a plurality of collecting portions resting on and movable vertically with respect thereto, electrostatic discharge means operatively associated with said vertical collecting portions, means associated with each of said assemblies for lifting said collecting portions, said means being operative in each assembly to drop said collecting portions in each assembly in succession on said immobile base and being operatively staggered in said series whereby to avoid dropping of said vertical collecting portions of said assemblies in unison, and dust receiving means located in line with said vertical collecting portions whereby dust dislodged therefrom falls into said receiving means.

'7. In an electrostatic precipitator, a collecting electrode comprising an articulated plate including a plurality of vertical plates arranged substantially in a common plane with their edges in juxtaposition with the juxtaposed edges turned out in opposite directions to provide reinforcing ribs and one of the turned out edges being turned back in and terminating on the surface of the juxtaposed plate to provide a reinforced lap joint.

8. In an electrostatic precipitator, the combination which comprises an electrostatic disthe articles of which are separately, vertically movable with respect to said base, means on said base for holding said articulated plate, said means permitting vertical movement of said articles, means for lifting said articles and dropping them in succession onto said base and dust receiving means in alignment with said articles whereby dust dislodged from said articles falls into said dust receiving means.

9. In an electrostatic precipitator, a collecting electrode assembly which comprises a horizontally disposed beam, a second horizontally disposed beam above and in vertical alignment therewith, electrode supporting means adjacent one side of the first named beam, electrode supporting means adiacent the other side of the first named beam. collecting electrode units supported in said electrode supporting means with their upper edges resting freely against the sides of said second beam and means for holding said electrodes in contact with the sides of said second beam, said electrode supporting means and 12 said holding means beingso constructed as to permit vertical movement of said collectingelectrode units, and means for lifting and dropping said collecting electrode units. 7

10. Apparatus according to claim 3 in which the lifting means comprises a lifting bar horizontally disposed between and spanning aplurality of said articles, means for supporting said lifting bar in a horizontal position, means connecting said lifting bar to said spanned collecting electrode units, at least during upward movement of said bar, means for lifting and dropping one end of said bar whereby to cause the articles spanned by said bar to be elevated to progressively different elevations from which they progressively drop onto said base.

11. Apparatus according to claim 8 in which the lift means comprises a lifting bar horizontally disposed between and spanning a plurality of said articles, means for supporting said lifting bar in a horizontal position, means connecting said lifting bar to said spanned collecting electrode units, at least during upward movement of said bar, means for lifting and dropping one end of said bar whereby to cause the articles spanned by said bar to be elevated to progressively different elevations from which they progressively drop onto said base, and means for lifting the other end of said bar whereby to cause said articles to be elevated to progressively different elevations in the other direction from which they drop progressively onto said base.

12. In an electrostatic precipitator, an electrode assembly which comprises a discharge electrode frame mounted in vertical position, a plurality of discharge electrodes arranged vertically in said frame, a platelike collecting electrode arranged on each side of said frame and parallel thereto and having vertical reinforcing ribs projecting inwardly toward said frame and to each other thereby providing a plurality of vertical panels on said platelike electrodes, said discharge electrodes being arranged to provide a group of uniformly spaced electrodes for each of said panels the end electrodes of which are uniformly spaced with respect to said vertical ribs and spaced farther from the end electrode of the adjacent group than the distance between the group electrodes.

'13. In an electrostatic precipitator, an element of collecting electrode which comprises a flat plate having parallel edges, unitary reinforcing ribs along each edge so arranged that the rib of one edge pro ects substantially in the opposite direction to the rib of the other edge, one of said ribs being turned backwardly toward said plate away from the edge of said plate, said turned back portion extending substantially to the plane of said plate. 7

14. In an electrostatic precibitator the combination which comprises conduit means for conducting dust laden gases, a horizontally disposed housing forming part of said conduit means and having open ends communicating with said conduit means and forming inlet and outlet means to said housing, a plurality of longitudinal beams arranged within said housing in a plurality of uniformly spaced horizontal and uniformly spaced vertical rows and provided with vertical sides, the beams of at least all but the top of said horizontal rows being open at the top and bottom over at least a port on of their length, crossplates extending into the open tops of said beams and forming a unitary structure therewith and having an enlarged upper portion, alined vertical slots in said enlarged upper portion of said crossplates substantially in alinement with the innermost side of the outside beams and each side of the intermediate beams, a plurality of flat platelike collecting electrodes having their bottom edges disposed within the said slots and their upper edges resting against the sides of the corresponding longitudinal beam in the next higher row, electrostatic discharge means operatively associated with the collecting electrodes, cover means spanning the open topped longitudinal beams adjacent in the same horizontal row, said cover means extending from the top of one side of one beam to the top of the other side of the other beam and sloping downwardly to each of said sides, the vertical slots in said cross-pieces being so located with respect to said covers as to provide a passage leading into the vertical channel formed by the sides of the beam and means for raising and dropping said electrodes to dislodge any dust accumulated thereon.

15. The apparatus of claim 14 in which said collecting electrodes comprise a plurality of separate plates arranged substantially in a common plane with their edges in juxtaposition, and adapted for vertical movement with respect to each other and in which said electrode raising and dropping means comprises a plurality of horizontal lifting bars located in vertical alinement with said longitudinal beams and spanning a plurality of said plates, means for supporting each end of said lifting bar and means for lifting and dropping at least one end of said lifting bar and engaging means on said lifting bar for engaging the spanned plates at least during vertical movement of said lifting bar. 1

16. The apparatus of claim 15 in which said engaging means comprises a headed pin projecting laterally from said lifting bar and an undercut lot on the innerface of said plate, closed at the top and open at the bottom, and adapted to engage over the head of said pin.

17. The apparatus of claim 14 in which said juxtaposed plates have one of the juxtaposed edges turned inwardly to provide a reinforced rib and the other turned outwardly toward said electrostatic discharge means, and then inwardly and terminating on the surface of the juxtaposed plate to provide a reinforced lap joint.

18. In an electrostatic precipitator the combination which comprises a plurality of elongated inverted U-shaped collecting electrode units, arranged in spaced vertical and spaced horizontal rows, with the bottom edges of each unit in each horizontal row in the same horizontal plane, and the center line of each unit in each vertical row in the same vertical plane, the spaced between the vertical rows being such as to provide a long narrow opening between the bottom edges of the unit in one row and the bights of the units of the next lower row.

19. In an electrostatic precipitator the combination which comprises vertically disposed collecting means having dust receiving means at the bottom and intermediate the height thereof dividing said collecting means into separate electrode units each of which consists of a plurality of vertical panels, electrostatic means associated with each unit and having at least one vertical electrode associated with each of said panels, and means for dislodging dust from said collecting means.

EDUARD DEGIORGI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,433,266 Fisher Oct 24, 1922 1,463,352 Weiskopf July 31, 1923 1,495,363 Weiskopf May 27, 1924 1,541,704 Gies June 9, 1925 1,588,072 Weiskopf June 9, 1926 1,773,876 Seipp Aug. 26, 1930 2,040,378 Hedberg May 12, 1936 2,271,597 Lodge Feb. 3, 1942 FOREIGN PATENTS Number Country Date 505,795 Germany Feb. 27, 1926 677,102 Germany May 25, 1939 321,869 Great Gritain Nov. 21, 1929 445,258 Great Britain Apr. 6, 1936

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