US2593377A - Gas cleaning apparatus - Google Patents

Description

A ril 15, 1952 Filed May 15, 1946 H. A. WINTERMUTE GAS CLEANING APPARATUS 2 SHEETS-SHEET l April 15, 1952 H. A. WINTERMUTE GAS CLEANING APPARATUS 2 SHEETS-SHEET 2 Filed May 15, 1946 g] wu M1101 Patented Apr. 15, 1952 UNITED STATES PATENT OFFICE GAS CLEANING APPARATUS Application May 15, 1946, Serial No. 669,917

Claims. 1

This invention relates to gas cleaning apparatus and more particularly to apparatus whereby suspended particles contained in air or other gases may be successively charged, flocculated and collected.

An object of the invention is to provide an improved gas cleaning device which is particularly eifective in removing from a stream of gas flowing therethrough extremely fine suspended particulate matter such as gas black, smoke, carbon black, mist and the like. The efiiciency of removal of extremely fine particles is high and the device of the invention is capable of cleaning gases that ordinary mechanical cleaning devices cannot handle at all and that other electrical gas cleaning apparatus cannot treat as effectively. Although the device of the present invention is especially suitable for cleaning gas bearing very fine particles, it also may be used to advantage in the treatment of gases for the removal of larger particles.

Another object is to provide gas cleaning apparatus of relatively simple construction which can be cheaply built and economically operated, which is simple to operate and which requires a minimum of attention and maintenance.

Gas cleaning apparatus in accordance with the invention includes a casing providing a conduit for the flow of gas therethrough. Within the casing there are disposed, successively in the direction of gas flow, particle-charging means, means for contacting the gas stream with an extended electrically conductive surface, and particle-collecting means. The particle-charging means may include spaced, discharge electrodes and electrodes complementary thereto. The gas contacting means may comprise a grounded, perforate metallic member, such as one or more woven wire screens. The particle-collecting means specifically embodied in the modifications of the invention described herein are either me chanical or electrical; however, such means may be of any suitable character and may include gas and liquid contact apparatus.

Other objects and advantages of the invention, not specifically referred to hereinbefore, will in part be apparent and in part pointed out in the following description taken in connection with the accompanying drawings wherein:

Fig. 1 is a horizontal sectional view, a fragment being shown in plan, of one form of the invention taken along the line l--l of Fig. 2;

Fig. 2 is a vertical sectional view taken along the line 2-2 of Fig. 1;

Fig. 3 is a horizontal sectional view of a modi- 2 fied form of the invention taken along the line 3'3 of Fig. 4, and

Fig. 4 is a vertical sectional view taken along the line 4-4 of Fig. 3.

Referring to Figs. 1 and 2 of the drawings, there is shown a gas cleaning apparatus having 2. casing 10 providing a gas inlet H at the left and a gas outlet l2 at the right. Means (not shown). such as a fan or blower, circulates gas to be cleaned through the casing in the directional sense of the arrow in Fig. 1. In the casing 10, there are disposed, successively in the direction of gas flow, a particle-charging means, designatedgenerally by the reference numeral 13, grounded metallic gas-contacting means, generally shown at [4, and particle-collecting means, generally referred to by the numeral [5.

The particle-charging means, as shown, has complementary fine wire electrodes I6 and grounded extended surface electrodes Ill. The fine wire electrodes are suspended from a spider l8, formed of rigid conducting material, which, in turn, is supported from the top of the housing by an insulator l9 and an insulating bushing 20. A lead 2 I, which passes through the bushing, connects the spider, and, hence, the fine wire electrodes, to a source of high potential current 22. Weights 23, attached to the bottoms of the fine wire electrodes, serve to hold the wires taut in the gas stream.

Extended surface electrodes ll may take the form of vertically arranged, columnar, metallic members. As shown, they are grounded tothe housing In, which may be of metallic construction. They are spaced from and disposed parallel to the fine wire electrodes.

The complementary electrodes are arranged, in the embodiment shown in Figs. 1 and 2, in two banks extending transversely of the gas stream in the housing; however, a single bank or more than two banks may be employed, as desired, in different circumstances, as where lower or higher gas velocities are encountered.

The source of high potential current 22 may be of conventional design, but, as illustrated, includes a transformer 23, rectifying tubes 24 and condensers 25. The lead wire 26 from the source of high potential current is connected. to the housing Hi, to the screen l4 and to ground. It will be seen that the extended surface electrodes l1, being electrically connected to the housing 10, are thereby grounded.

Passing now to the grounded gas contacting means l4, it will be observed that such means specifically takes the form of a metallic woven 7 ing zone.

a screen positioned transversely of the housing and located between the particle-charging means and the particle-collecting means to be described.

The screen may be encompassed in a frame 2'8 so that it can be readily removed through a door (not shown) in the top of the housing for cleaning or replacement. If desired, a suitable cleaning mechanism may be provided for cleaning the screen in place. As shown in the drawings, the

screen is grounded to the lead wire 26 through a suitable connector, but it may be otherwise grounded as by simple electrical contact with the grounded housing l9.

As shown at l5 in Fig. 1, the particle-collecting means comprises two identical filter elements 28 closely spaced from one another in the direction of gas flow and extending entirely across the interior of the housing. These filter elements are positioned in a frame 29 and, as in the case of the screen 54, provision may be made for removing them from the housing for the purpose of cleaning or replacement. Filter elements comprising glass wool coated with oil or other viscous material having a low vapor pressure have been found satisfactory.

In operation, gas to be cleaned is circulated through the housing, passing first through the particle-charging zone, thence in contact with the grounded metallic member, and finally through the particle-collecting zone.

In the particle-charging zone, the dust-laden gas passes through a high tension electric field wherein it is subjected to electrical discharges, by which the particles carried by the gas stream are charged, as will be understood by those skilled in the art. Some precipitation of particles may occur in this zone, and, in such circumstances, it may be desirable to provide means for cleaning the electrodes. Such means may be conventional electrode rapping or brushing devices, electrode washing devices, or other suitable devices. Although some precipitation may here' occur, much, and in the case of very fine suspended matter and/or high gas stream velocities, most of the gas-borne particles are carried in a highly charged condition to and in contact with the grounded wire screen [4.

As the gas stream bearing the charged particles passes through the meshes of the screen it, a flocculation appears to take place and, by some mechanism not thoroughly understood, the particles in the gas stream emerging from the wire screen are in condition for ready recovery by a particle-collecting means such as the filters 28.

The source of power 22 is shown connected to the gas cleaning apparatus in such manner that the high tension electrodes is are positively charged. Reversal of connections may be made to place a negative charge on the high tension electrodes, if desired. Such reversal of polarity will not greatly affect the operation of the apparatus.

Referring now to Figs. 3 and 4, the modified form of the invention therein shown is in many respects similar to the form shown in Figs. 1 and 2. In the modified form, three gas treating zones are present: a particle-charging zone, a zone in which the gas stream is contacted with a grounded metallic member, and a particle-collect- However, the modified form differs from the first-described form principally in that (a) the perforated metallic gas-contacting member is of specifically modified construction, (1)) the particle-collecting means is of the electrical precipitator type, and (c) the source of high po- 4 tential current and the manner in which it is connected to certain elements of the apparatus also is specifically changed.

In Figs. 3 and 4, the apparatus shown has a casing or housing 3E providing a gas inlet 3| and a gas outlet 32, the direction of gas fiow being from left to right as seen in these figures.

The particle-charging means, designated generally 33, includes two transverse banks of complementary electrodes, the high tension electrodes being shown at 34 and the extended surface electrodes being shown at 35. High tension electrode spiders 36 support the high tension electrode wires in spaced relation and, in turn, are supported upon the sides of the housing by insulators 3! and insulating bushing 38, the bushing providing access to the spider for the high tension lead 39 which is electrically connected to the spider and, through the latter, to the high tension electrodes 34. Extended surface electrodes 35 may be grounded to the housing 3D, if the latter is of metal construction, or they may be grounded, as.

shown, through connectors 49.

The gas contacting means includes a zig-zag Woven wire screen 4| supported by end members 42.

afiixed to the angles of the screen at suitable distances laterally thereof. The screen may be grounded through connector 44, or it may be connected to the housing if the latter is grounded. The zig-zag construction of the screen increases the available surface area for contact with the gas stream and serves to deflect the flowing gas in its passage through the meshes; such factors improve the efficiency of the screen. Some collection of particles may take place at the screen, and screen-rapping or cleaning devices may be employed for the purpose of dislodging matter that adheres to the screen.

Reference numeral 45 designates the particle collecting means which is similar in construction to the particle-charging means 33 previously described. It has high tension electrodes 46 and extended surface electrodes 41, the former being connected to high potential lead 48 and the latter being grounded through connectors 49.

The source of high potential current has a transformer 59, rectifying tubes 5| and is constructed and arranged to provide a positive high potential outlet 39, a negative high potential outlet 48, and a grounded-circuit outlet 52. These outlets are connected to the components of the apparatus as hereinbefore described.

It will be noted that the high potential electrodes of the particle-charging means are positively charged and that the corresponding electrodes of the particle-collecting means are negatively charged, the extended surface electrodes of both means being grounded. The polarities of the high potential electrodes may be reversed or of the same sign.

In the operation of the apparatus of Figs. 3 and 4, gas containing suspended matter to be removed is circulated through the housing 30 from left to right. Charging of suspended particles and some precipitation thereof takes place in zone 33; flocculation of charged particles occurs in zone 4|; and final precipitation and collection is accomplished in zone 45.

Apparatus in accordance with the invention provides means for subjecting gas to be cleaned to three treatments in series, the treatments being consecutively non-similar.

Whereas, the illustrative embodiments of the Additional support for the screen is pro-' vided by vertical wires 43 soldered or otherwise invention herein shown and "described each have a single casing in which are disposed the three gas treating elements, it will be apparent that a unitary casing is not essential, provided suitable means is employed for constraining a mass of gas to be treated to flow in a stream through the three treating zones hereinbefore described. It will also be apparent that the casing need not be made of electrically conducting material, as described, but may be made of non-conducting material, in which case the necessary electrical connections to the apparatus elements can be made by conductors passing into or through the casing and directly connected to the elements. Moreover, the intermediate gas contacting means need not be made of metal as long as its gas contacting surfaces are sufiiciently conducting to be maintained at a preselected potential under the conditions of operation; and such potential need not be the ground potential as specifically described, but, as will be understood, may be any suitable preselected potential either above or below the ground potential.

The intermediate gas contacting means located in the fiocculating zone may comprise a plurality of wire screens or the like extending across the gas stream and spaced apart in the direction of gas fiow to provide additional gas contact surface.

From the foregoing description it will be seen that there has been provided an efficient, simple and very satisfactory air cleaning apparatus. Since modifications will be obvious to those skilled in the art in the light of the disclosure, the invention is not limited to the specific embodiments herein shown and described except as defined by the claims.

I claim:

1. Gas cleaning apparatus which comprises a casing providing a conduit for the flow of gas therethrough said casing having disposed therewithin successively in the direction of gas flow particle-charging means, means for contacting the gas stream with an extended grounded metallic surface, and filter means for collecting particles from the gas stream, said grounded metallic surface means being perforate, extending substantially across the gas stream and being positioned at a location substantially removed from the electrical,v influence of an opposing charged electrode.

2. Gas cleaning apparatus which comprises a casing providing a conduit for the flow of gas therethrough said casing having disposed therewithin successively in the direction of gas flow particle-charging means, means for contacting the gas stream with an extended grounded metallic surface, and filter means comprising glass wool coated with a viscous substance supported transversely of the casing for collecting particles from the gas stream, said grounded metallic surface means being perforate, extending substantially across the gas stream and being positioned at a location substantially removed from the electrical influence of an opposing charged electrode.

3. Gas cleaning apparatus which comprises a casing providing a conduit for the flow of gas therethrough said casing having disposed therewithin successively in the direction of gas flow particle-charging means including extended sur- 7 face electrodes maintained at a preselected potential and spaced complementary discharge electrodes maintained at a high potential with respect to said extended surface electrodes, means ,for contacting the gas stream with an extended 6 metallicsurface maintained at the same potential as said extended surface electrodes, and filter means for collecting particles from the gas stream, said grounded metallic surface means being perforate, extending substantially across the gas stream and being positioned at a location substantially removed from the electrical influence of an opposing charged electrode.

4. Gas cleaning apparatus which comprises a casing providing a conduit for the flow of gas therethrough, said casing having disposed therewithin successively in the direction of gas flow particle-charging means, means for contacting the gas stream with an extended grounded metallic surface, and means for mechanically collecting particles from the gas stream, said grounded metallic surface means being perforate, extending substantially across the gas stream and being positioned at a location substantially removed from the electrical influence of an opposing charged electrode.

5. Gas cleaning apparatus which comprises a casing providing a conduit for the flow of gas therethrough, said casing having disposed therewithin successively in the direction of gas flow particle-charging means, a grounded, conductive, perforated, metallic diaphragm through which the gas passes, and filter means for collecting particles from the gas stream, said metallic diaphragm extending substantially across the gas stream and being positioned at a location substantially removed from the electrical influence of an opposing charged electrode.

6. A method of removing finely divided suspended particles from a gas stream comprising subjecting the gas stream to corona discharge whereby the particles are substantially charged with electricity of a given polarity, substantially removing the electric charge from the suspended particles by contacting the gas stream with a perforated, grounded, metallic, neutralizing surface extending substantially across the gas stream whereby the particles tend to form suspended agglomerates, and mechanically separating the agglomerated suspended particles from the gas stream.

'7. A method of removing finely divided suspended particles from a gas stream comprising subjecting the gas stream to corona discharge whereby the particles are substantially charged with electricity of a given polarity, substantially removing the electric charge from the suspended particles by contacting the gas stream with a perforated, grounded, metallic, neutralizing surface extending substantially across the gas stream, whereby the particles tend to form suspended agglomerates, and filtering the agglomerated spspended particles from the gas stream.

8. Gas cleaning apparatus which comprises a casing providing a conduit for the flow of gas therethrough said casing having disposed therewithin successively in the direction of ga flow particle-charging means, means for contacting the gas stream with an extended grounded metallic surface, and particle collecting means, .said grounded metallic surface means being perforate, extending substantially across the gas stream and being positioned at a location substantially removed from the electrical influence of an opposing charged electrode.

9. A method of removing finely divided suspended particles from a gas stream comprising subjecting the gas stream to corona discharge whereby the particles are substantially charged 75 with electricity of a given polarity, substantially aseasv'r 7 removing electric charge from the suspended particles by'contacting the gas stream with a perforated, grounded, metallic, neutralizing surface extending substantially across the gas stream,

whereby the particles tend to form suspended agglomerates, and separating the agglomerated suspended particles from the gas stream.

. 10. Gas cleaning apparatus as defined in claim 5 wherein said perforated, metallic diaphragm and frame are removable from the casing as a unit.

HARRY A. WINTERMUTE.

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

UNITED STATES PATENTS Number Number I Name Date Seaman May 30, 1916 Anderson Apr. 12, 1932 Simpson Feb. 7, 1939 White Dec. 24, 1940 Williams Sept. 29, 1942 Steel Mar. 7, 1944, Jacob Aug. 7, 1944 FOREIGN PATENTS Country Date Germany Dec. 29, 1926'

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