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Oct. 15, 1946. *A. F. MESTON 2,409,579 COMPOSITE ELECTRODE Filed June 16, 1944 ' lI|1 Mzuj.wm?al.w 4 Sheets-Sheet 1 Oct. ‘15, 1946; A. F. MESTON 2,409,579 COMPOSITE ELECTRODE’ Filed‘June 16, 1944 i FM Y 4 Sheets-Sheet 2 0a. 15, 1946. \ l A. f'F. MESTON 2,409,579 COMPOSITE ELECTRODE Filed Ju‘ne‘ 16, 1944. 4 Sheets-Sheet‘ 3 _ Oct. 15,1946. _ - A, F, MEs'roN COMPOSITE ELECTRODE Filed June 16, 1944 'I 2,409,579 _ 4 Sheets-Sheet 4 r59. 1:. 2,409,579 Patented Oct. 15, 1946 UNITED STATES PATENT OFFICE I 2,409,579 COMPOSITE ELECTRODE Archibald F. Meston, Bound Brook, N. J ., assign or to Research Corporation, New York, N. Y., a corporation of New York Application June 16, 1944, Serial No. 540,609 11 Claims. (Cl. 183-7) , 1 2 ‘This invention relates to a system of electrodes useful in establishing an electric ?eld or electric tary electrodes arranged to provide discharge ?elds across a gas~?lled space for the purpose ing zones; one of the electrodes being a composite of ionizing the gas and electrically transporting particles suspended in the gas. It relates in par ticular to a composite electrode comprising one discharge electrode having extended non-dis charge surfaces with longitudinally spaced de or more attenuated elements from which corona 7 members in the depressions for initiating dis zones alternately with non-discharge precipitat pressions therein and a plurality of attenuated charges which will have low energy output due discharge can be caused to emanate and an ad to electric shading by the adjacent extended jacent element of extended surface upon which a strong non-discharging electric ?eld can be 10 surfaces. These and other objects and advantages are caused to terminate. obtained by the provision in an electrical pro In the following description and exposition, the cipitator of complementary electrodes including term “composite electrode” refers to an electrode a composite electrode comprising an extended which functions as a discharge electrode, but dif fers from the more usual types of discharge elec~ 15 surface portion free from surface elements of radius of curvature small enough to produce trodes in construction and in the electrical con corona discharge under operating conditions and ditions it provides, as will be pointed out here having grooves or depressed regions spaced lon inafter. More descriptively, it is sometimes re gitudinally therealong, and a plurality of at ferred to as a “discharge electrode” or “precipi tenuated members of very small radius of our tating electrode.” The term “collecting elec vature supported in the depressed regions for trode” will be used to designate those electrodes producing corona discharge when the appara which in common electrical precipitation practice tus is energized, no discharge producing portion provide surfaces for the reception or collection of said attenuated members extending outward of particles which have been'driven from a gas stream by an electric ?eld, andupon which a 25 ly toward a complementary electrode beyond the extended surface portion adjacent said discharge portion, at least, of the electric ?eld terminates. portion. ‘ The gas treating apparatus described in illustrat While the character of surface which will pro ing the present invention comprises one or more duce corona, discharge will vary with such con— composite electrodes and one or more comple mentary collecting electrodes. Electrodes are 30 ditions as potential difference, electrode space and character of the gas, theextended surface complementary to each other when they are member of the composite discharge electrode maintained, respectively, at different electrical should not, in general, include surface portions potentials and serve as the opposite terminals of having a radius of curvature substantially less the electric ?elds which exist in the medium or 35 than one-tenth inch while the attenuated dis space between them. charge members will include surface portions A principal object of the invention is to provide having very small radii of curvature. For ex electric treating means including a composite ample, in the preferred embodiment of the in discharge electrode which, when energized at a ventiondirected at applications where the pro complementary electrode of the so-called “col 40 duction-of ozone is to be held to low values, the radii of curvature of the discharge members are lecting” type, effects the formation of a charg of the order of ?ve-thousandths of an inch or ing ?eld, comprising an ionizing discharge, and less. a transporting or precipitation field, without dis The invention will be more particularly de charge, in closely adjacent zones. 45 scribed with reference to the accompanying draw A particular object of the present invention is ings in which: to provide for gas treaters comprising comple Fig. ,1 is a fragmentary elevation in partial sec mentary electrodes, a discharge electrode of the tion of an electrical treater embodying the prin composite type having extended non-discharge ciples of the invention; surfaces including depressed portions, and at Fig, 2 is a section on line 2—2 of Fig. 1; tenuated discharge elements positioned in said 'Fig. 3 is an end view of the composite electrode depressions, no discharge portion of said elements of'Fig. 1; extending outwardly toward a complementary Fla. 4115 a fragmentary elevation of an embodi electrode beyond the adjacent extended surfaces. ment of the invention comprising electrodes in Another object of the invention is the provision ‘ of an electrical precipitate!‘ having complemen 55 the form of ?at plates; suitable potential difference with respect to a 2,409,579 3 4 Fig. 5 is a fragmentary longitudinal section through the precipitator illustrated in Fig. 4 on line 5-5 of Fig. 4; The position of prongs V differs from the po sition of prongs W in that the former are elec trically shaded or masked by extended surface on one side only. With equal lengths of prong, ending an equal distance from the surface of tu Fig. 6 is an enlarged sectional view of a de tail of the composite electrodes illustrated in Figs. 4 and 9; bular electrode 2|, greater discharge can be ex pected from prongs V than from prongs W, which Fig. 7 is a sectional elevation of a treater con structed in accordance with the present inven tion, and including a composite electrode with bulging portions and discharge elements sup 10 ported in grooves in the bulging portions; Fig. 8 is a plan view of a discharge element useful in the composite electrode shown in Fig. 7; Fig. 9 is a fragmentary sectional elevation' taken on line 9—9 in Fig. 10 of a treater With 15 electrodes comprising extended ?at plates and embodying bulging portions about the discharge is often desirable because the gas passing prongs V has not been subjected to prior ionizing dis charges. But the discharge from the V prongs can be diminished if desired by shortening them or otherwise varying the discharge distance to complementary electrode 2| or, by adjusting their position so as to vary the shading provided by surface I6. An effective treating apparatus of the form illustrated in Figs. 1, 2 and 3 may comprise ex elements; tended surface portions I0, I! approximately two Fig. 10 is a fragmentary longitudinal section on inches in diameter, with a groove 29 one-quarter inch deep and two-inch overall in width, the min imum radius of the surface of the groove being line I0—Ill in Fig. 9; Fig. 11 is a fragmentary view, partially in sec tion, of an alternate composite electrode which can be used in the treater illustrated in Fig. '7; Fig. 12 is a fragmentary plan view and Fig. 13 is a fragmentary end View of a treater with ex one-half inch. The collecting electrode tube 2| may, in such case, advantageously be about four inches inside diameter. Eight prongs W having a length of one-eighth inch and eight prongs V having a length of 136 inch made of .005 inch diameter tungsten wire tended plate collecting electrodes and comprising another embodiment of a composite electrode with bulging portions constructed in accordance with the present invention; and may be used, spaced about 91/2 inches apart along member Ill. Fig. 14 is an enlarged perspective view of a con 3O structional detail of the composite electrode of Figs. 12 and 13. Figs. 1, 2 and 3 illustrate the application of the principles of the invention to electrical treaters having a cylindrical or “pipe” collecting electrode. In this embodiment of the invention the com posite precipitating electrode consists of a piece of smooth straight tubing Iii joined to a similar piece of tubing II by two intermediate parts I2 With an apparatus of the form and dimensions described, effective precipitation of suspended particles from air, with no spark-over and little or no production of ozone, can be obtained with a voltage of 30 to 35 kv. (root mean square) maintained across the electrodes by connecting the precipitating electrode to a source of recti ?ed high potential alternating current, such as the transformer and rotary mechanical switch arrangement, commonly used in electrical pre and I3 and a rounded structure on the other end 40 cipitation circuits and grounding the collecting of tube member I!) made up of members I6 and electrode. II; also, attenuated prong members W clamped The conditions realized by energization of the in joint i5 between members I2 and I3 and simi arrangement just described can be summarized lar prong members V clamped. in joint I9 be as follows: tween members I6 and I7. Portions of the ex 45 An electric ?eld is established which is most terior surface of members I2 and I3 are cut down intense, on the average over its entire length, be to form, when joined together, a broad groove tween electrode surfaces from which no corona 29 with rounded shoulders and it is at the bottom discharge emanates. This portion of the elec of this groove that prongs W are attached. Mem tric ?eld is designated as a precipitating ?eld. ber I2 has a boss I2’ which ?ts into a comple 50 Portions of the electrical ?elds of appreciably less mentary recess in member I3 for purposes of average intensity terminate on attenuated por alignment. A stud I4 screwed into member I 3 tions of that electrode known as the discharge extends through a hole in member I2 and the two electrode and cause local corona discharges there members are pulled tightly together clamping from. This portion or portions of the ?eld is des prongs W between them by screwing up nut I 4’. ignated as the ionizing ?eld though it may func The free ends of members I2 and I3 are pressed tion to some extent as a precipitating ?eld. into the interior of tube members I0 and II, re The average strengths of the precipitating and spectively, making a carefully aligned continu ionizing ?elds will vary with the distance of the ous structure of the electrode at this point, non-ionizing and ionizing portions, respectively, Tip member I7, like intermediate member I6, 60 has an arcuate outer surface. The inner surface where it joins member I6 is formed as the frus tum of a cone with apex at the point of gener ation of the arcuate surface. The conical surface is normal to the arcuate surface where it joins 6 the latter. In this example the apex angle is 84°. A stud I8 projects out of the back of member I‘I, extends through a hole in member l6 and, with of the discharge electrode from the collecting electrodes. The relative values of precipitating and ionizing ?elds can thus be made to vary by changing the shape and dimensions of the elec trodes, particularly of the discharge electrode. The ?atter and smoother the non-ionizing sur faces of the complementary electrodes, the closer they can be positioned at a given voltage differ ence Without disruptive discharge and the strong nut I8’, fastens the two members together, er the resulting electric ?eld. clamping prongs V in joint I 9 and causing the 70 The more attenuated and isolated the discharge prongs to project normally from the surface. elements. the more intense will be the discharge The boss IS’ on member I6 projects into mem from them, conditions of voltage and electrode ber I9 and makes a friction ?t therewith. spacing remaining constant. A cylindrical collecting electrode concentric When the discharge elements are positioned in with the precipitating electrode is indicated at 2|. 75 close proximity to a portion of the non-discharg 2,409,579 5 6 _ ing surface, but no closer to the. collecting elec trode than adjacent portions. of the non-dis charging surface, the discharge elements will be masked or shadowed by the close-by non-dis charging surface and a very high voltage drop. 5 suitable reciprocating source of power by means of rod as- Rod 44. is, for practical purposes, an extension- of rod 45; also, of rod d5.’ which may across the electrodes will be required, if, the elec tric field at the discharge elements is to become intense enough to cause corona discharge. Under these conditions, the precipitating ?eld will have become very strong and effective for migrating 10 The partial telescoping of the. several pipe por tions provides for cleaning selected areas on the inner surface of electrode 35 where the electric charged particles when the ionizing ?eld is still relatively weak and comprises low energy dis charges only. Such conditions are especially de sirable when air is to be cleaned for human con sumption. The‘intensity of the discharges and the resulting yield of ozone can be controlled while the precipitating field is maintained at .as near maximum strength as is practical. As indicated above, the preferred embodiment 43, respectively, and which'is connected to any be attached to the operating mechanism of an electrode (not shown) similar to electrode 35. ?elds are the most intense and most apt to cre ate back discharges from that electrode. The composite type discharge electrode in Fig. 'l is made‘ up of a tube 48 on which are mounted tapered ferrule-like members, 49 with bulging portions 55. They are preferably placed on tube 48 in pairs with the bulging portion of one adja cent the bulging portion of the other. Mem bers 49 are so shaped‘ that when a pair of them is positioned on tube 48, asshown, a trough or de of the invention includes prongs or just points, pression 5|‘ exists between the members, and, in ionizing discharge. The closer together the 1944). this depression, appropriate discharge elements rather than edges or wires, as discharging ele— 52 are positioned. These elements can be simi ments. A prong projecting out from a surface lar to those disclosed in Figs. 1, 2 and 3, and a can be the terminal of lines of force extending method of preparing a grid structure with such in every direction except back along the prong. This means that an electric ?eld which is rela 25 elements is described in applicant’s copending ap plication Serial No. 391,791, filed May 3', 1941 tively weak a short distance from the prong will (now U. S Patent No 2,352,651, dated July 4, be strong enough at the prong itself to cause an A member 53, preferably with rounded closed end as shown, is mounted on the end of prongs are placed, the weaker will the field at tube 5.8. In this embodiment of the inven 30 each prong become, or, putting it another way, tion the discharge points are positioned more the more intense the adjacent ?eld must be to closely to collecting electrode 35 than is the sur cause corona to emanate from the points. When face of member 48, but the bulging portions 59 the prongs touch one another the condition pre~ project as far, or- farther, toward complementary sented by an edge is obtained. A wire, posh electrode 35 than do elements 52, receive much of tioned adjacent and parallel to an extended sur~ the electric ?eld which terminates on the com face, for instance, can be used as a discharge ele posite electrode, and thus electrically shade the ' ment in the present invention as will be pointed discharge elements and depress the discharges out below. that form upon or immediately adjacent them. Figs. 4 and 5 illustrate how the invention can The voltage between the complementary elec be applied advantageously to treaters with ver trodes just described is usually held at values tical plates that divide the gas to be treated into which causes the portions of the electric ?eld horizontally extending streams and serve as elec adjacent the bulging portions to be Very intense. trodes for the collection of material electrically Under such conditions, while collecting certain removed from the gas. Such collecting electrode 45 sorts of particulate matter, at least, trouble from plates are designated‘by numeral 25. The com~ back corona be realised unless the collected posite electrode is made up of two plates 26, pref material is removed almost as ‘soon as it is de erably of metal, which have trough-like defor posited. The cleaning mechanism attached to mations 2'! therein, the troughs extending verti electrode 35 is arranged to remove the material by cally in the sheets. The plates are fastened to scraping the collecting surfaces ‘ opposite the 50 gether with, for example, hollow rivets, such as bulging portions and the discharge elements be rivet 2-9 shown in Fig. 6, with the under sides of tween the bulging portions. , the troughs touching back to back and in ion Fig. 8 shows a discharge member made from a g~=itudinal alignment. Pins 35 are inserted in thin metal sheet and comprising a plurality of the holes in at ve'least some of the rivets and, in holes or slots 3i near the ends of pins '35, dis 55 sharp prongs 54. Hole 55 is for the insertion of a supporting rod. This member can be used in charge wires 32, which may be of tungsten or nichrome eter, are supported and of thelongitudinally order of .085in, inch but spa making up a composite electrode such as the one illustrated in Fig. '7 in which case it takes the place of the wire grid with prongs 52 indicated in cially removed from the walls of, the troughs. The electrode ‘may be supported from high ten 60 Fig. 7. In Fig. 11 a composite electrode is illustrated in sion bus bars 33 by means of straps 34. The which the supporting member 51 has been ex embodiment of the invention shown in Figs. ‘1 panded by hydraulic pressure. for instance, while and 5 provides zones of suppressed corona dis~ being held in a demountable forming die, to form charge—at the wires extending in troughs ‘21, alternating with extended regions of strong uni~ 65 bulging portions 58. Between each pair of bulg ing portions 58, a groove or depression 59 is left form electric fields free from discharge--which for the reception of a discharge member Bil. exits between the flat portions of plates 25 and Member 65 is made, preferably from a coil spring, plates 25. ‘ of very ?ne wire, and has the advantages of sim Fig. '7 illustrates a unit of a pipe type precipi plicity in shape, ease in manufacture, and ef? 70 tator with collecting electrode 35 made up of ciency in discharge performance which have been pipe portions 36, 3?’ and 33 which partially tele disclosed in U. S. Patent No. 2,231,330, issued to scope one within the other in the order men C. M. Gove, February 11, 1941. The discharges tioned. The telescoping is accomplished by emanate from the outer portions of the several means of operating mechanism which is attached to portions 315, ‘31 and33 at fastenings 4!, 42 and " helices of the coil spring and the intensity of the 7 2,409,579 8 discharges-for a given voltage difference be tween the complementary electrodes, can be de creased by decreasing the pitch of the spring—— which spaces the turns of wire more closely, and material and prevent discharge from the top edges of the members. It will be seen that the composite electrode of the invention may be varied in form and con struction over a wide range without departing from the principles of the invention as de?ned in the claims. This application is a continuation-in-part of by decreasing the diameter of the coi1—which positions the discharge portions more closely within the electric shading of the bulging sur face portions. The end of the composite elec trode may be closed with a plug 6|. my application Serial No. 391,789, ?led May 3, Figs. 9 and 10 illustrate a construction which 10 1941, now U. S. Patent #2364541, dated Decem permits the use of bulging portions with a dis ber 12, 1944. charge element positioned in a depression therein, I claim: in accordance with the teachings of the ‘present 1. In an electrical treater including comple invention, in electric-treaters comprising par allel plate electrodes. The collecting electrodes are represented by plates 64 (to which baffles, scrapers and the like may be attached in accord ance with the knowledge of the gas treating art), mentary discharge and collecting electrodes, a discharge electrode comprising an extended sur face member including a surface portion depressed below the level of adjacent surface portions to provide a concavity in said extended surface and a cover plate for the treater is designated by member, and attenuated discharge elements posi numeral 65, the cover including, in this example, 20 tioned in said concavity wholly below the level a housing 66 for a bus bar 6‘! from which depends of said adjacent surface portions. strap 63 for the support of composite discharge 2. In an electrical treater with complementary electrode 63, and similar straps, not shown, for discharge and collecting electrodes, a discharge supporting other composite electrodes. Com electrode comprising an extended surface mem posite electrode 68 is built about a ?at plate 69. ber, said extended surface member including non Spaced longitudinally along both sides of plate discharging surface portions convex toward the 89 and attached thereto are a plurality of mem~ complementary surfaces of the collecting elec bers "50. These members 10 are shaped with a trodes and concavities adjacent said convex sur pair of bulging portions ‘H, with a depression 12 face portions, and discharge elements supported between, which extend transversely of plate 69. . wholly in said concavities. A discharge member 15, which is here indicated 3. In an electrical treater with complementary as a very ?ne wire, is supported in each depres discharge and collecting electrodes, a discharge sion, but spaced from adjacent surfaces, by pins electrode comprising an extended surface mem 39. Members 10 are preferably spaced along ber substantially parallel to the complementary plate 69 so that a member on one side of the plate surface of a collecting electrode, said extended is immediately opposite a similar member on the surface member including concavities therein opposite side and a single row of rivets 29, shown which open only toward the complementary sur in more detail in Fig. 6, can be used to attach face of one collecting electrode, and discharge both members. Members 10 are preferably producing elements supported wholly within said shaped to slope gradually from the bulging por 40 concavities. tions ‘H to the supporting plate 69 to present n0n~ 4. In an electrical treater with complementary turbulent ?ow conditions to the gas passing discharge and collecting electrodes, a discharge through the treater. At the entrance end of the electrode comprising an extended surface mem treating passages, members 70', with a single ber including surface portions substantially par bulge, can be used to advantage. In this arrange 45 allel to the complementary surface of a collecting ment. only one nearby extended surface ‘H’ at electrode alternating with bulging portions pre tracts portions of the electric ?eld, which would senting non-discharging convex surfaces toward otherwise terminate on a wire 15, but if it is ad the complementary electrode and defining con visable to offset this condition, pins 3!] can be cavities in said member, and discharge producing shortened or bent with the result that wires 15 50 elements supported wholly within said concavities. will be farther from plates 64, respectively, and 5. In an electrical treater including comple closer to portions 1!’ and less corona discharge mentary discharge and collecting electrodes, a will emanate from them. discharge electrode comprising a member having The construction shown in Figs. 12 to 14 con extended non-discharge surfaces including sur templates limiting the charging and precipitating 55 face portions depressed below the level of adja functions to spaced apart composite members Bil cent surface portions to provide concavities in which are supported on horizontally extending said extended surface member and attenuated bars Q8. The extended surface portions of mem discharge elements positioned in said concavities, bers ?t are shaped similar to members 10 in Fig. 8 ' no discharge portion of said elements extending except that where the edges 8! of the opposing 60 toward a complementary collecting electrode be members are brought together cut-outs are made yond the extended surfaces adjacent said con topro-vide for bars 90. Rivets 29 project through cavities. the bottom of the depressed portions 83 of members 86 preferably just above or just below bars f'ii. Discharge wires 85 are secured in the holes or 6. In an electrical precipitator including col lecting electrodes de?ning a gas passage therebe tween, a discharge electrode in said gas passage comprising an extended surface member includ ing a surface portion depressed below the level of adjacent surface portions to provide a concavity slots 3! in top pins 86, pass easily through open ‘ ings 5i in the pins 36 below and are held under tension by means of a spring 83 under or adjacent in the surface thereof extending transversely of the bottom of the electrode. Discharge can be 70 said gas passage, and attenuated discharge ele dire toward the roof of the treater by having ments in said concavity wholly below the level of discharge wire 8?, supported by topmost pins 30, the extended surface portions adjacent said con pass over the top of the composite electrode as cavity. shown. Cover plates 38 can be fastened over the 7. In' an electrical precipitator including col openings of members 80 to prevent ingress of 75 lecting electrodes defining a gas passage therebe 2,409,579 9 10 tween, a discharge electrode in said gas passage comprising an extended surface member includ tially concentrically of said collecting electrode ing spaced convex bulges extending transversely of said gas passage and de?ning a concave trans verse furrow therebetween, and attenuated dis charge elements positioned wholly within said furrow. 8. In an electrical precipitator including a cylin drical collecting electrode, a discharge electrode positioned within said collecting electrode com prising a cylindrical member extending substan tially concentrically of said collecting electrode and including a circumferential concavity, and and including spaced circumferential convex bulges de?ning a circumferential concavity there between, and attenuating discharge elements posi tioned wholly within said concavity. 10. A composite discharge electrode comprising an extended surface member including a surface portion depressed below the level of adjacent sur face portions to provide a concavity in the surface thereof, and attenuated discharge elements in said concavity wholly below the level of the extended surface portions adjacent said concavity. 11. A composite discharge electrode comprising attenuated discharge elements positioned wholly an extended surface member including spaced within said concavity. 15 convex bulges de?ning a concave furrow there 9. In an electrical precipitator including a cy~ between, and attenuated discharge elements posi lindrical collecting electrode, a discharge electrode tioned wholly within said furrow. positioned within said collecting electrode com prising a cylindrical member extending substan ARCHIBALD F. MESTON.