US1903640A - Electrical precipitator - Google Patents

Description

April 1933. H. A. WINTERMUTE 1,903,640

ELECTRICAL PRECIPITATOR Filed Aug. 22, 1931 s Sheets-Shet 1,

April W33. H. A. WINTERMUTE ELECTRICAL PRECIPITATOR Filed Aug. 22. 1931 @Igg! Egg @1313;

. 'mfifl H, 1933. H. A. WINTERMUTE ELECTRICAL PRECIPITATOR- Filed Aug. 22, 1931 3 Sheets-Sheet 3 Patented Apr. lill, 31933 HARRY A. WINTERMUTE, OF PLAINFIELD, NEW JERSEY, ASSIGNOR TO RESEARCH CORPORATION, OF NEW YORK, N, Y., A CORPORATION OF NEW YO ELECTRICAL rnncrrr'ra'roa Application filed August 22, 1931. Serial No. 558,809.

Thisinvention relates to apparatus for the electrical precipitation of suspended particles from gases, the apparatus being of the type which comprises a casing with a gas inlt and a gas outlet, collecting electrodes and discharge electrodes within the casing, and means for impressing a high difference of potentialpreferably non-alternating as regards polarity, between the collecting and to discharge electrodes. It more especially relates to a collecting electrode of new and useful construction which, when incorporated into an electrical precipitator in the novel manner to be described in the following speci- 115 fication, provides marked improvements over the art of electrically removing particles from gases as practiced in the past.

It can be said, in general, that the more slowly the gases to be cleaned of suspended as particles are passed through an electrical precipitator, the more complete will be the removal of the particles. It,is obvious, however, that, for economical reasons, the gases will be passed through a precipitator just as as rapidly as possible while obtaining the desired or permissible degree of cleanliness. One of the factors that limits the volume of gas which can be passed through a precipitator per unit of time is the distribution or lack of distribution of gases in the difierent passages or ducts in which precipitation takes place. If the gas flow in one or more passages greatly exceeds the flow in other passages, the total volume being cleaned will have to be diminished until the velocity in the.

over burdened passage or "passages is decreased to where good cleaning is obtained therein.

The design of the inlet and outlet lines has 40 much to do with'proper distribution and it is important in precipitators as generally constructed that good distribution between the different passages be secured at the inlet because the collecting electrodes in most precinitators are imperforate and the gas velocity at the entrance of a passage is retained throughout the length of the passage. lln the present invention, the passages are defined by perforate collecting electrodes which permit a further distribution of gases between passages while the gases are passing through the precipitator.

Certain particles when precipitated upon the collecting surfaces fall away and get back into the gas stream to be reprecipitated or to find their way out of the precipitator with the gases. Some particles, upon precipita-v tion, build up into fairly compact but easily disintegrated deposits. When these deposits become of a critical thickness, they may fall away with more or less disintegration and form a dense cloud of resuspended material. In general, this material will fall by gravity into the hoppers provided below but a certain amount will get back into the gas stream and be carried along with it. The number of particles present at the moment of dislodgement is so great that it is impossible to immediately recharge them all electrically, and mechanical means such as the flowing gases and mechanical obstructions have more to do with their control at the moment than do the electrical forces. Bafiles cooperating with the collecting surfaces are especially useful at such times. They divert the gas stream away from the surface where the dislodged material is falling and they provide obstructions to the horizontal travel of the dislodged material along the surface of the collecting electrode.

I (Another type of particle that is dificult to hold without baffles is that found in heterogeneous dusts. Some of these particles have difierent electrical characteristics than others and, when precipitated together, some do not remain deposited on the surface but 'dance about and along the surface of the collecting electrodes and often out of the precipitator. Experiments with gases from boiler plants,

which contain unburned carbonaceous part-i- 9 cles which are difficult to retain on the collecting electrodes, have proved that bafies to have good gas distribution through the precipitator and to provide suitable electrodes including secluded surfaces upon which the material to be precipitated can be temporarily retained; but it is usually necessary to provide for dislodging the deposited material be cause it seldom dislod es of itself as completely and satisfactori y as is necessary or desirable. In the present invention, the collecting electrodes are made up of small units which will separately vibrate or shake when the shaking mechanism is operated and the battles are hung with minimumrestraint towards vibration.

It has been common practice in the past to make collecting electrodes of imperforate thin plates with angles or other stifl'ening members rigidly fastened to theplates to prevent warping. When the angles were placed vertically, they would act as bafiies in horizontal flow precipitators. But the difliculty with this construction is that when the plates are made stifi enough to eliminatewarping, they are too stiff to vibrate properly when the collected material is to be shaken oif.

An object of the present invention is to provide an electrical precipitator in which the collecting electrodes permit an equalization of the gas distribution near the entrance ends of the several gas passages. Another object is to provide a collecting electrode in which a plurality of spaced members are alined to define one side of a gas passage, the spacing of the members being greater at the entrance of the gas passage to obtain equal distribution of the gases. A further object is to provide a collecting electrode of the type stated in which the individual members are so supported that shaking of the electrode results in individual vibration of the component members. A further object is to provide an electrode of the type stated which includes baflies that are not rigidly attached to the electrode members.

These and other objects of the invention will be apparent from the following specification when taken with the accompanying drawings, in which:

Fig. 1 is a longitudinal section of a precigjitator embodying the invention,

ig. 2 is a fragmentary horizontal section on line 22 of Fig. l,

Fig. 3 is a side elevation of Fig. 2,

Fig. 4 is an end view of one of the collecting electrodes shown in Fig. 2,

Figs. 5 and 6 are fragmentary views, in side and end elevations, respectively, showin in detail one end of one of the collecting e ectrodes shown in Fig. 2,

Fig. 7 is a fragmentary sectional view of another embodiment of the invention,

Fig. 8 is a fragmentary and enlarged sectional view of the electrode support shown in Fig. 7,

F ig. 9 is a fragmentary view, taken in end 1,9oaeao elevation, of the members shown in Fig. 8. and

Figs. 10 and 11 indicate, by cross sections, other forms of baflles which can be used in the invention.

In the drawings, the reference numeral 1 identifies the precipitator casing which has inlet and outlet openings 2, 3, respectively, between which a plurality of discharge electrodes 4 are supported inalined rows by a framework 5 which is suspended from insulators 6. The collecting electrodes include the horizontal bars 7, 8 which are carried by a plurality of transverse supports 9 through baffle strips 10 which, as shown in Fig. 2, may take the form of elongated plates that are somewhat wider than the bars 7, 8.

Each collecting electrode includes a plurality of relatively independent unit elements that are non-rigidly supported by the bars 7, 8, the units having such form and relative location that an equalization of gas flow in the several parallel gas passages may be effected near the inlet end of the precipitator casin The collecting elements 11 adjacent the Inlet preferably take the form of rods, either solid or hollow, which have enlarged heads 12 for supporting the same from the upper bar 7, which bar preferably has the form of an inverted channel. The lower ends of the bars 11 pass loosely through openings in'the bar 8 which thus serves to guide or position the rods Without interfering with free vibration of each rod when the collecting electrode is shaken by any appropriate means, such as by bars 13 which are connected to the lower end of an intermediate baflie 10 and extend through the casing wall to a vibrating or rapping device 14.

The succeeding ortion of the collecting electrode may be ormed of closely spaced rods, but preferably comprises relatively fiat plate elements 15 whose upperends are supported by the channel bar 7 and Whose lower ends are loosely received within the channel or bar 8. The plate elements 15 are preferably spaced apart ata lesser distance than the collecting elements 11.

The lower support or guiding bar 8 may conveniently take the form of two oppositely directed channel members, as illustrated, but other arrangements for maintaining the alinement of the elements of the collecting electrodes, while permitting such freedom of relative movement as is desirable to facilitate rapping, will occur to those familiar with the design and construction of electrical percipitators.

To permit substantial vibration of each plate 15 when the electrode is jarred, the plates are relatively narrow and may be corrugated to secure sufiicient stiffness to prevent warping of the lates. Either flat or corrugated plates may e stiffened by locating the lateral edges of the plates within channels 16, as shown in Figs. 2 and 3.

In this construction, the plates 15 are preferably connected to the supporting members and the stiffening channels at only one end, as by fasteners 17 passed through the channel support 7, the channel ribs 16 and the plates 15 The discharge electrodes may be energized with high voltage current supplied through a step-up transformer 20 and rectified by a mechanical switch 21 which is run in synchronism with the alterations of the supply current. The pre'cipitator casing 1 and the collecting electrodes which are supported by it are grounded, as by a lead 21'."

It will be noted that the various elements which provide the collecting surface of each electrode are loosely suspended so that one element imparts but little rigidity to another, and eflective vibration of the various elements is readily produced. In large precipitators, however, the collecting electrodes may be of such length and height that the weight of each individual assembly or complete collecting electrode makes it difficult to vibrate the total electrode through the agency of one suspending member, such as the intermediate bafile 10, Fig. 1. The electrode assembly may, of course, be divided into similar sections provided with individual rapping devices but I prefer to employ the construction shown in Figs. 7, 8 and 9 when an assembly such as shown in Fig. 1 cannot be conveniently vibrated by a single rapping device.

Many of the parts of this embodiment of the invention are, or may be substantially identical with corresponding parts of the Fig. 1 structure and are identified on the drawings by the same reference numerals but will not be described in detail. Theprincipal structural differences arise from the fact that the channel bars 7 8 of the electrode assembly are carried directly by the transverse supports 9 and the baffles 10 have spaced openings so located that the baflies hang loosely on the upper bar 7 and clear of the lower bar 8. Weight supporting rods pass through the channels 7, 8 and are threaded to receive nuts 23 upon which the bars rest, the upper ends of rods 22 being threaded into fittings 24 which are bolted to the members 9. A shaking rod 25 extends through each lower channel 8 and short sleeves or bushings 26 are fixed on the rod 25, by set screws 27, within each channel. Upon oscillation of rod 25 by a shaking device, not shown, the bushing 26 imparts hammer blows to the channel 8 to vibrate the unit elements 11, 15, and intermediate baffles 18. The main baflies 10 are apertured to pass over chan nels 7, 8 and have their upper ends within the spaced sides of the channel members 9, and their lower ends are secured to shaker rods 28 that extend to the exterior of casing 1 for oscillation by a suitable shaking device.

The described fiat plate type of battle strips are not essential as other shapes may be employed. As shown in Fig. 10, the bafiles may consist of tubes or rods 29 which are of substantially larger diameter than the rods 11, or, as shown in Fig. 11, the baffles may be formed of tubes 30 which are indented from opposite sides to figure 8 form in cross section.

A stream of gas entering the casing at opening 2 will not, in general, be evenly distributed as it enters the several parallel gas passages provided by the collecting electrodes. However, as the electrode elements adjacent the inlet ends of the passages are spaced apart by appreciable distances,for instance, rods 11 of inch diameter and placed 1 inches center to center have been found to give good results, the passage receiving an excessive quantity of gas builds up a resistance to gas flow in excess of that set up in passages in which the gas flow is of less velocity. The tendency is, therefore; as the gas in the high velocity passage meet with the resistance of the passage,'=""such as that set up by bafiles 10, 18, to move across into an adjacent passage. In this way an equalized distribution of the gas is secured near the entrance portions of the gas passages.

It is to be noted that the several baflles are not rigid portions of the collecting electrodes and therefore the baflles are free to 'vibrate of themselves and they permit free vibration of the other, collecting surfaces. The bafiles assist in the rapid equalization of the gas distribution and they provide quiet regions where dislodged dust may collect and drop vertically into storage bins.

I claim:

1. In an electrical precipitator, a casing having inlet and outlet openings, a plurality of collecting electrodes dividing the space within said easing into a plurality of parallel gas passages, and discharge electrodes in each of said gas passages, the portions of said collecting electrodes adjacent the inlet opening of said casing being apertured to permitequalization of gas flow in the several gas passages, and the remaining portions of said electrodes being substantially imperforate.

2. In an electrical precipitator, a casing said casing, collecting electrodes cooperating with said discharge electrodes and dividing the space within said casing into a plurality of gas passages, the portions of said collecting electrodes adjacent the inlet opening of said casing comprising elements spaced apart to permit equalization of gas flow in the several passages and bafiies on each of said collecting electrodes, interspaced therewith and extending transversely of the gas passages.

3. In an electrical precipitator, a casing having inlet and outlet openings, a plurality of alined rows of discharge electrodes within said casing, and collecting electrodes cooperating with said discharge electrodes and dividing the space within said casing into a plurality of gas passages, the portions of said collecting electrodes adjacent the inlet opening of said casing comprising elements spaced apart to permit equalization of gas flow in the several passages, and the portions of said collecting electrodes adjacent the outlet opening of said casing comprising members closely spaced to prevent substantial How of gas between adjacent passages.

4. An electricalprecipitator comprising a casing having inlet and outlet openings, discharge electrodes alined in rows between said openings, and collecting electrodes adjacentsaid rows of discharge electrodes and defining a plurality of parallel gas passages, each of said collecting electrodes including supporting members and spaced elements carried by said members, the spacing of the said elements being greater adjacent the inlet than the outlet end of each gas passage.

5. The invention as set forth in claim 4, wherein each of said elements is supported by said members at only one end, in combination with means for rapping one supporting member of each collecting electrode. thereby to cause independent vibration of each of said elements.

6. The invention as set forth in claim 4,

wherein each collecting electrode includes a plurality of battles projecting beyond one face of said electrode and transversely of the direction of gas flow.

7. In an electrical precipitator, a collecting electrode for cooperation with another collecting electrode to define'a gas passage, said collecting electrode including an upper and a lower support, and elements carried by said supports, the elements adjacent one end of said supports being spaced apart by greater distances than the elements at the opposite ends of said supports.

8. The invention as set forth in claim 7. wherein the elements adjacent one end of said supports comprise rods spaced apart by distances substantially greater than the diameter of the rods.

9. The invention as set forth in claim 7 wherein the elements at one end comprise spaced rods, and the elements at the other end comprise plates forming a substantially continuous collecting surface.

10. In an electrical precipitator, a collecting electrode structure comprising a plurality of spaced electrode elements alined in a row, baflie members interspaced with said collecting elements and a discharge electrode structure comprising discharge electrode elements alined in a row parallel to and spaced from said collecting electrode structure.

11. In an electrical precipitator, a collecting electrode structure comprising supporting means, a plurality of spaced elements carried by said means and alined in a row, certain of said elements being collecting elements defining one boundary of a gas passage, and other of said elements being battle elements interspaced with said collecting elements and a discharge electrode structure comprising discharge electrode elements alined in a row parallel to and spaced from said collecting electrode structure.

12. In an electrical precipitator, a collecting electrode structure comprising an elongated supporting member extending in the direction of gas flow through the precipitator, collecting elements and bafiie members spaced apart along said supporting member, said baflle members being interspaced with said collecting elements and a discharge electrode structure comprising discharge electrode elements alined in a row parallel to and spaced from said collecting electrode structure.

13. In an electrical precipitator, a collecting electrode structure comprising an alined row of spaced collecting elements, balile members in said row and interspaced with said collecting elements, means supporting said collecting elements and bafile members for independent vibratory movement and a dis charge electrode structure comprising dis charge electrode elements alined in a row parallel to and spaced from said collecting electrode structure.

14:. In an electrical precipitator, a plurality of spaced bafiie members alined in a row. a plurality of collecting elements alined with and spaced between said bafiie members. means including said bafile members for supporting said collecting elements in said alined position and a plurality of discharge elements alined in a row parallel to and spaced from said collecting elements.

15. The invent on as set forth in claim 14. in combination with auxiliary baflles spaced from said bafile members and between collecting elements.

16. In an electrical precipitator. a casing having inlet and outlet openings, :1 collecting electrode system comprising collecting elements and bafile members, said elements and members being alined in rows to form parallel gas passages, and each of said rows i be members and a discharge electrode sysneoaeeo including interspaced collecting elements and tem comprising discharge elements alined in rows parallel to and spaced from said rows of collecting elements and bafie members.

17 In an electrical precipitator, the combination with a casing having inlet and outlet openings, and discharge electrodes, of a collecting electrode system comprising a plurality of spaced collecting elements and be members alined in rows to form parallel gas passages each of said rows including a plurality of bafile members and collecting elements between adjacent bafile members, said elements being spaced from each other and from said bafiie members.

18. The invention as set forth in claim 17, in combination with means supporting said collecting elements and baflie members for independent vibratory movement, and means for efiecting vibratory movement thereof.

19. A collecting electrode comprising a plurality of spaced baflle members alined in a row, a bar carried by said baflie members and extending along the upper ends thereof, and

a plurality of spaced collecting elements having their upper ends supported by said bar,

said collecting elements being alined with and interspaced with said bafie members.

In testimony whereof, I afiix my signature.

HARRY A. WINTERMUTE.

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