US2397302A - Collecting electrode for electrical precipitators - Google Patents

Description

March 26, 1946.-

COLLECTING ELECTRODES FOR ELECTRICAL PREGIPITATORS Filed Dec. 30, 1943 3 Sheets-Sheet 2 LEE a Kr? WW mm mw V mH m m a w w #55 F %m 6 n. 8 3

March 26, 1946. F. H, VIETS 2,397,302

COLLECTING ELECTRODES FOR ELECTRICAL PRECIPITATORS Filed Dec. 50, 1943 3 Sheets-Sheet 3 I INVENTOR. H. on) H. V15 T5 ATTORNEY Patented Mar. 26, 1946 UNITED STATES PATENT OFFICE Floyd. H. Viets, Glendale,. Calif assignor to; Western Precipitation Corporation, LosAngeles, Calii'., acorporation of California.

Application December 30, 1943,. SerialNo 516,156

2 Claims. (C1, 1837) This invention relates to collecting electrodes of electrical precipitation apparatus for use in the separation of suspended material from gases, and particularly tocollecting electrodes of the typein which a thin film of liquid is passed, preferably continuously, over the collecting electrode surfaces on which the material is precipitated.

More specifically, the invention is concerned with liquid-flushedcollecting electrodes comprising vertical pipes or tubes. Such collecting electrodes are ordinarily assembled within a housing and mounted adjacent their upper ends on a horizontally extending wall or header plate. The gas is passed vertically through the collecting electrode pipes, and an opposing precipitating electrode extends centrally within each pipe. Water or other suitable liquid is supplied to the space aroundthe upper ends of the collecting electrodes above the header plate, and flows over the upper edges of thes electrodes and down the inside surfaces thereof, on which the material is precipitated. The space above the header plate constitutes a liquid supply chamber or reservoir, and the upper ends of' the collecting electrodes extend upwardly above the header plate and act as over"- flow lips or weirs to control the flow of water into each electrode.

An electrical precipitator of this general type is shown in United States Patent of Crowder et al. No. 1,968,334, issued July 31', 1934. Such liquidflushed pipe collecting electrodes are useful in precipitators ofthesingle-stage type, as disclosed in the above mentioned patent; in which'the precipitating electrodes within the pipes are dis-' charging electrodes such as small diameter wires, or rods provided with sharp edges or points,

whereby a corona discharge is maintained for the purpose of both. charging and precipitating suspended particles in the electric field between thes electrodes and the collecting electrodes.

Similar liquid-flushed collecting electrodes are also useful in electrical precipitators of the twostage type, in which the charging and precipitat-' tions, as shown for example in United States patent of Anderson, No. 2,192,172, issued March 5, 1940.

In this case Electrical precipitators of the types above lie-- scribed are well known in the art; The present invention is concerned only with an advantageous form of collecting electrode for use-in any type of precipitator employing liquid-flushed tubular or pipe collecting electrodes, and it will be understoodthat such electrodes may be used in connection with any type or form of opposing precipitatin electrode.

The collecting electrode pipes are generally of substantially uniform diameter throughout the majorportion of their height toprovide the desired spacing of the collecting surface, and the liquid film thereon, from the opposing electrode.

It is desirable that this portion of the collecting electrode surface be free from sharp edges or other irregularities or discontinuities that would tend to disturb the smooth flow of the liquid filmor to cause electrical discharge from the collecting electrode. It is also desirable that the upper end portion of the collecting electrode including the overflow lip or weir at which the liquid film is formed, as well as the lower end portion of the collecting electrode where the liquid leaves the collecting surface, be of materially greater diameter than the major'portion of thepipe, so as to prevent electric discharge from the ends ofthe collecting electrode and to provide for formin and breaking the" liquid film at positions of reduced' electric fiel'cl strength.

The principal object of this invention isto provide asimpl'e and inexpensive collecting electrode structure that meets all of the above requirements and provides all of the above-mentioned desired features.

pening in the-head'erplate need be of only'sufficient diameter to receive the pipe.

In accordance with this invention. the collecting electrode comprises a pipe, preferably of substantially uniform diameter throughout the ma,-

jorportion ofits length, having its upper end pertion flared outward so t-hatthe inside diameter of the upper edge of the pipe is materially greater than that ofthe major portion of the pipe. A weir ring memberis adjustably mounted around the upper end of the pipe, and extends upward outward. The inner face of this ring is preferably recessed outward at the upper portion of the ring, to receive the lower end of the pipe and provide a substantially smooth continuous inner surface at the juncture of the pipe and the ring.

The accompanying drawings illustrate a preferred form of collecting electrode, according to my invention, and referring thereto:

.Fig. 1 is a partial vertical section of an electrical precipltator, with severalcollecting electrodes and associated precipitating electrodes shown in elevation;

Fig, 2 is a horizontal section on line 2-2 in Fig. 1;

Fig. 3 is a vertical section showing the upper end portion of one of the collecting electrodes,

I taken on line '33 in Fig. 2;

Fig. 4 is a horizontal section on Fig. 1; and v Fig. 5 is a vertical section of the lowerend portion of one of the collecting electrodes, taken on line 5-5 in Fig. 4.

A plurality of tubular collecting electrodes I are shown as extending vertically through and supported upon a header plate 2, it being under; stood that these electrodes are ordinarily mounted within an enclosed precipitator housing provided with gas inlet'and gas outlet means at opposite sides of the header plate so as to provide for passage of gas to be treated, vertically through the several electrodes, as more fully shown and described in the above-mentioned United States Patent 1,968,334. 1

. Each collecting electrode comprises a pipe 3 of suitable length and diameter, which is of substantially uniform diameter throughout the major portion of its length. The upper end of the pipe extends above the header plate 2, and is flared outwardly as shown at 4 to provide an upper edge line 44 in 5 of materially greater inside diameter than the 7 major portion of the pipe. At the upper edge the external surface of the pipe is preferably finished so as to provide a short cylindrical bearing surface 6.

Each of the collecting electrode pipes extends through an opening 8 in header plate 2 and is shown as supported on said header plate by means of an outwardly projecting annular flange 9 welded or otherwise secured to the pipe and its cylindrical inner surface in close sliding ongagement with cylindrical face 6 on the pipe. Ring, I2 extends upward above the upper edge 5 of the pipe and its upper edge l3 may be either plain as shown or may, if desired, be notched or serrated as shown for example in Fig. '7 of said 7 Patent 1,968,334. Means are provided for supporting and adjusting the weir ring, comprising for example four adjusting screws or bolts l5, extending through outwardly projecting members such as lugs l 6 at equally spaced positions around the ring and provided with heads l1 and nuts l8 bearing against the upper and lower faces respectively of said lugs. The'lower ends of adjusting screws l5 engage nuts. or other internally threaded members [9 welded or otherwise secured to flange 9. Thus, by suitable manipulation of screws l5 and nuts 18 the weir ring [2 may be a raised or lowered at the position of each adjusting screw, so as to provide vertical adjustment of the weir ring relativeto pipe 3 and also for vertical angular adjustment of said ring relative to i said pipe. Although the ring fits quite closely about the external face 6 at the upper end of the 1 pipe in order toiprovide a substantially liquidtight engagement, the relationship is such as to permit some angular tilting of the ring relative to the pipe. It will be observed that the vertical dimension of face 6 is quite short relative to the diameter thereof so as not to unduly limit such tilting movement, and the fit at this point need not be extremely close in order to substantially prevent leakage of liquid between the pipe'and the ring.

Each collecting electrode is also provided at its lower end with a, ring 2|, removably' secured thereto as by means of set screws 22. The lower portion of ring 2| has its inner surface flared thickness of pipe 3, so as to receive the lower.

end of said pipe with the internal surfaces of the pipe and ring substantially flush with each other and provide a substantially smooth continuous internal surface at the juncture of the inner sur# faces of the pipe and ring, as indicatedat 25; In erecting the apparatus, the collecting electrode pipes 3 are passed from-above through. the opening 8 in the header plate, which openings'need be of only sufiicient size to receive the main por-' tion of the pipes, and the lower end rings 2! are thereafter secured to the pipes.

The lower ends'of the pipes are shown as held 7 in properly spaced and vertically alined position by means of adjusting screws 21 engaging nuts or other internally threaded members 28'which are secured to small plates 29 supported by suitable frame members 30.

The precipitating electrodes are shown as comprising discharge electrode'members 3|, such as' .wires or square twisted rods extending axially provided for alining the lower 'ends of the discharge electrodes 3!, and said electrodes may also be provided at their lower ends with tensioning.

V weights 31 secured thereto by rods 38. I Said rods '38 are preferably-of sufficient diameter to prevent corona discharge therefrom; and preferably ex tend upward to a position above the lower ends of the collecting electrodes.

The collecting electrodes are ordinarily main.- tained at ground potential, while the entire discharge electrode systemincluding discharge elec trodes 3| and the associated supporting and spacing means is mounted on insulating supports; jso

that the necessary high potential may be maintained between the discharge and collecting electrodes to cause corona discharge from discharge electrodes 3|.

The space above the header plate 2 serves as a liquid reservoir, and this space may be divided into a plurality of separate liquid supply compartments or troughs, as by means of suitably spaced walls 41 extending upwardly from header plate 2 to a position somewhat above the upper edges or overflow lips I3 of the weir rings. A plurality of collecting electrodes are arranged with their upper ends within each of the liquid supply compartments or troughs thus provided between adjacent walls 4|. Liquid is supplied through pipes 42 and downwardly extending nip-- ples 43 which deliver the liquid above the header plate and below the weir rings l2, preferably at positions between each set of four collecting electrodes as indicated in Fig. 2.

After the apparatus is erected, the liquid to be used for flushing, which may be either water, oil, or any other suitable liquid, is supplied to each of the compartments defined by walls 4!, and the weir rings 12 of the several electrodes in each such compartment are then carefully adjusted as described above, in order to provide substantially equa1 flow of liquid into the respective electrodes and also for substantially uniform flow of liquid at all circumferential positions around the upper edge of each of the weir rings. This provides for maintaining a substantially uniform downward flow of liquid through all the electrodes in a thin film distributed substantially uniformly over the entire inner surface of each electrode.

The liquid film is formed at the upper edge of the weir ring, at a position spaced from the opposing precipitating electrode 3| by a distance materially reater than the spacing between the precipitating electrode and the major portion of the inner surface of the collecting electrode, so as to avoid electrical disturbances, and the same considerations apply where the liquid leaves the collecting electrode surface at the lower edge 23 of bottom ring 22. The entire surface over which the liquid flows, between the top and bottom edges of each collecting electrode, is free"from sharp edges or surface discontinuities or irregularities that might tend to disturb the smooth flow of the liquid or to cause electrical disturbances.

Although the precipitating electrodes are in this case shown as discharge electrodes, it will be understood that the collecting electrode structure of this invention may also be employed with nondischarging precipitating electrodes as brought out hereinabove.

I claim:

1. A collecting electrode for use .in liquidflushed electrical precipitators, comprising: a ver tically extending pipe of substantially uniform inside diameter throughout the major portion of its length and having its upper end portion flared outward to provide an upper edge of materially increased diameter; and a ring removably mounted on the lower end of said pipe and flared downward and outward, the lower end of said ring having an inside diameter materially greater than said major portion of the pipe.

2; A collecting electrode as set forth in claim 1, the upper end of said ring being recessed internally, and the lower end portion of said pipe ex tending within the recess in the ring with the inner surfaces of the pipe and ring substantially flush with each other at the juncture thereof.

FLOYD H. VIETS.

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