US3200566A

US3200566A - Emission electrode for electrostatic precipitators

Info

Publication number: US3200566A
Application number: US209182A
Authority: US
Inventors: Gustafsson Stig; Maartmann Sten
Original assignee: Svenska Flaktfabriken AB
Current assignee: Svenska Flaktfabriken AB
Priority date: 1961-07-12
Filing date: 1962-07-11
Publication date: 1965-08-17
Anticipated expiration: 1982-08-17
Also published as: GB998268A

Description

United States Patent O 3,200,566 EMISSION ELEQTlR-QDE FOR ELMZTRQSTATI C PRECTPITATURS Stig Gustafsson, Jonkoping, and Stein Maartmann, Klinten, Sweden, assignors to Alrtiebolaget venska Flakttabrn hen, Stockholm, Sweden Filed July 11, 1962, Ser. No. 209,182 Claims priority, application Sweden, daily 12, 1961, 7,224/61 3 Claims. (Cl. 55-152) The present invention relates to an emission electrode for electrostatic precipitators with a horizontal gas flow, each emission electrode consisting of a vertically mounted plate-like member made of sheet metal with a fiat center part or web and bent-up or rolled vertical edge stiifening strips. Since the efiiciency of precipitation of an electrostatic precipitator is highly depending upon the voltage used and as it can be proved that the efficiency in separation of heavier dust, that is to say with a particle size greater than 1 ,u, increases as the square of the voltage, it is of importance to make the electrostatic precipitators in such a way that the voltage can be kept at the highest possible value. With the types of emission electrodes used up to now the voltage can, it is true, be kept high, but in such electrodes it has been diflicult to provide a favorable current distribution without risk of flash-over. Especially in the cleaning of gases with high resistive dust this drawback has asserted itself. The invention, which relates to a new and improved embodiment of emission electrodes making possible a high voltage in combination with a favorable current distribution with a larger number of emitting projections per unit of surface, is characterized in that the edge strips are provided with a number of pressed-up wart-shaped projections which constitute the main emitting elements of the electrodes.

The pressed-up wart-shaped projections are in accordance with the present invention, provided on the two edge strips of the electrode on opposite sides of the plane of the web of the electrode. Another embodiment is characterized in that the pressed-up wart-shaped projections are directed towards opposite sides on each of the two edge strips of the electrode. The wart-shaped projections can in both cases be uniformly distributed along the edge strips, that is to say reckoned in the vertical extension of the electrode, or also be disposed in a differentiated distribution.

The invention will now be described with reference to the accompanying drawing, which shows an electrostatic precipitator equipped with emission electrodes in accordance with the invention, and wherein:

FIG. 1 is a longitudinal vertical section through an electrostatic precipitator;

FIG. 2 is an enlarged horizontal cross-section of one embodiment of an emission electrode having bent portions and wart-shaped projections on both sides;

FIG. 3 is a view like FIG. 2 but showing an electrode having edge strips with bent portions on only one side;

FIG. 2a is a partial side view of the FIG. 2 embodiment, taken on the line 2a-2a of FIG. 2; and

FIG. 3a is a partial side view of the FIG. 3 embodiment, taken on the line 3a3a of FIG. 3.

In the drawing 1 indicates the casing of an electrostatic precipitator equipped with a number of vertical emission electrodes 2, arranged in parallel rows, which in a known way are swingably suspended in a frame 3. The electrodes consist of sheet metal plate-like members with a fiat center part or web 3a with rolled or bent up edge stiffening 3,200,565 Patented Aug. 17, 1965 "ice strips 3b and 30 respectively, as is more evident from FIGS. 2 and 3 respectively. In accordance with the invention the electrodes are provided with emitting elements in the form of pressed-up wart-shaped projections 4 along the edge strips. The wart-shaped projections are, as shown in the drawing, rounded projections connected to the curved bent portion of each stiifening strip and extending in a direction substantially perpendicular to the plane of each web. As illustrated in the drawing, each of the rounded projections is pressed outwardly from the curved bent portion and has a substantially hemispherical smooth and unbroken peripheral outline. These wart-shaped projections can, as shown in FIG. 2, at each of the edge strips be directed to both sides of the plane of the electrode web; or, at one edge strip, be directed to one side and at the other edge strip to the opposite side as shown in FIG. 3. For the cleaning of the electrodes there are arranged rapping rods 5 attached below the electrodes and a rapping device 6 actuating said rods.

What we claim is:

1. An emission electrode for electrostatic precipitators in which a number of vertical plate-like electrodes are arranged in a co-planar row with the planes of the plates disposed parallel to the flow of gas thereover transversely across the width and edges, said emission electrode comprising a continuous smooth planar web bent at each longitudinal edge to form a vertical stiffening strip having a curved bent portion on at least one side of the plane of the web, and a plurality of vertically spaced, integral, rounded projections on the curved bent portion of each stiffening strip, said projections extending in a direction perpendicular to the plane of said web, each of said projections being pressed outwardly from said curved bent portions and having a substantially hemispherical smooth and unbroken peripheral outline.

2. An emission electrode as set forth in claim 1, in which the bent portions at opposite edges of the web are directed in opposite directions with respect to theplane of the web to place said rounded projections in staggered relationship relative to the plane of the web.

.3. An emission electrode as set forth in claim 1, in which the vertical stifiening strip at each edge of the electrode has a bent portion with rounded projections on each side of the plane of the web.

References Cited by the Examiner UNITED STATES PATENTS 832,767 10/06 Bridge 55--152 X 1,345,790 7/20 Lodge 55--129 X 1,767,338 6/30 Arras 55-130 1,931,436 10/33 Deutsch 55--152 X $395,431 4/40 Shively et al 55-152X 2,694,464 11/54 Winterrnute 55-152 2,737,258 3/56 Harlow 55154 X 2,812,035 11/57 Sohlman et al 55112 2,946,400 7/ Gustafsson 55--130 3,158,454 11/64 Gustafsson 55--154 X FOREIGN PATENTS 911,017 2/46 France.

344,705 1 1/ 21 Germany.

888,871 2/ 62 Great Britain.

ROBERT F; BURNETT, Primary Examiner.

HARRY B. THORNTON, Examiner.

Claims

1. AN EMISSION ELECTRODE FOR ELECTROSTATIC PRECIPITATORS IN WHICH A NUMBER OF VERTICAL PLATE-LIKE ELECTRODES ARE ARRANGED IN A CO-PLANAR ROW WITH THE PLANES OF THE PLATES DISPOSED PARALLEL TO THE FLOW OF GAS THEREOVER TRANSVERSELY ACROSS THE WIDTH AND EDGES, SAID EMISSION ELECTRODE COMPRISING A CONTINUOUS SMOOTH PLANAR WEB BENT AT EACH LONGITUDINAL EDGE TO FORM A VERTICAL STIFFENING STRIP HAVING A CURVED BENT PORTION ON AT LEAST ONE SIDE OF THE PLANE OF THE WEB, AND A PLURALITY OF VERTICALLY SPACED, INTERGRAL, ROUNDED PROJECTIONS ON THE CURVED BENT PORTION OF EACH STIFFENING STRIP, SAID PROJECTIONS EXTENDING IN A DIRECTION PERPENDICULAR TO THE PLANE OF SAID WEB, EACH OF SAID PROJECTIONS BEING PRESSED OUTWARDLY FROM SAID CURVED BENT PORTIONS AND HAVING A SUBSTANTIALLY HEMISPHERICAL SMOOTH AND UNBROKEN PERIPHERAL OUTLINE.