DE1163742B - Electrostatic precipitator - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school KL: B 03 c

German class: Ib-6

Number: 1 163 742

File number: G 24227 VI a / 1 b

Filing date: March 31, 1958

Opening day: February 27, 1964

The invention relates to an electrostatic precipitator with spaced apart upper and lower Electrodes, the upper electrode having a number of openings through which material, attracted by the lower electrode will get onto the top of the upper electrode can, with a conveyor for transporting material over the lower electrode and with a Voltage source that maintains a potential difference between the electrodes.

According to the invention it is proposed that one of the electrodes at the discharge end with an auxiliary electrode is provided to which a voltage is applied. It is thereby achieved that the mixture consists of a mixture or a mixture of already separated particles is directed in a desired direction for the purpose of separation increasing the final purity or quality of the sort. Appropriately the potential at the auxiliary electrode is approximately equal to the potential at the associated electrode Electrode made.

It has proven to be advantageous to place the auxiliary electrode above the discharge end of the associated electrode to arrange.

The features of the invention emerge from the following description with reference to the drawings Embodiments of the invention are described. In the drawings is

F i g. 1 is a perspective view of the important parts of the electric separator, with certain parts cut away to show the parts underneath

Fig. 2 is a perspective partial view, somewhat enlarged, which shows the arrangement of the braking electrode, F i g. 3 is a section along line 3-3 of FIG. 2,

4 is a vertical section through the separator, where the braking electrode has been omitted,

FIG. 5 shows a representation similar to FIG. 4 attached braking electrode,

F i g. 6 one of the F i g. 4 similar modification of the separator and the

7 shows a further modification of the separator discharge.

The in FIG. The embodiment of an electrostatic precipitator shown in FIG. 1 has a frame which is designated by 10. A first electrode plate 12 is attached to the top of this frame and extends over the entire length of the frame. At a certain distance above this electrode there are two electrode plates 14 a and 14 b arranged at a distance in the longitudinal direction. These electrode plates generally have electrostatic precipitators

Applicant:

General Mills, Inc., Minneapolis, Minn.

(V. St. A.)

Representative:

Dr.-Ing. H. Ruschke, patent attorney,

Berlin 33, Auguste-Viktoria-Str. 65

Named as inventor:

William Andreas Bradstad, Minneapolis, Minn.

(V. St. A.)

are of the same construction, each having a number of openings 16 which can easily be formed by stamping, the process leaving an upstanding cylindrical wall or collar 18 surrounding each opening. It should be pointed out at this point that the various cylindrical walls 18 must be so high that they exclude the return of the separated material through the openings 16 downwards after the material has been conveyed once onto the top of the electrodes 14 a or 14 b is.

Although the particular number of electrode plates mainly on the type and size Depending on the sorting to be carried out, the invention offers particular advantages when the various Plates are arranged vertically one above the other.

Therefore, at a certain distance above the electrode 14 a, there is another electrode plate 20, whose function which is similar to the electrode plate 12, while a further electrode plate 22 is shown above the electrode plate 20, which corresponds to the electrode 14 a. speaks.

All of the aforementioned electrode plates are electrically not with the help of a number of upright Conductive webs 24 held at certain heights, so that the different electrode plates on different Working potential can be maintained. The webs 24 are on the frame 10 by means of a Row of rivets 26 attached. However, since the various electrodes are related to certain heights must be held on each other, the heights to a large extent from that to be separated Depending on the material and the applied electrical potentials, each web is provided with a number of slits

409 510/99

zen 28 provided. An equal number of screws and nuts protrude through these slots outside, which are designated together with 30. In this way, the electrode plates can be on the the most favorable distance from each other can be set.

As shown in FIG. 1, the lowermost electrode 12 is held at ground potential with the aid of a conductor element 32. On the other hand, the negative electrodes 14 a and 14 b are kept at high direct current potentials by means of special conductors. Although it will be discussed in more detail later, it should already be said at this point that because the electrodes 14 a and 14 b are electrically isolated from one another, they do not need to be subjected to the same voltage conditions. The potentials fed to the electrodes 12, 14 a and 14 b are variable according to the material to be deposited.

At one end of the electrode 12 is a collecting container 42, the bottom of which is from the electrode is formed and which is provided with a hinged lock 44, which is a certain to be separated Releases material flow. A similar container 46 is arranged above the first container, its Bottom is formed in this case by the electrode 20 and also with a hinged lock is provided (denoted by 48). Because of the limited drawing area, these containers are only fragmentary shown; however, it is believed that the illustration is sufficient to clearly show that the material stored in the lower container 42 for conveyance on the top of the electrode 12 for Is available while the material contained in the upper container 46 is on top of the electrode 20 walks along.

Due to a vibration in the direction indicated by 68, the material is released from both containers 42 and 46 moved over the electrodes 12 and 20 and at the same time shaken so that whose particles keep jumping up and down. This process makes certain particles electrostatic Pick up charges with the effect that they move upwards to the corresponding electrodes 14 'and 22 are attracted, with some particles jumping through those openings 16 that the Containers are closest, while other particles are near the electrodes 12 for some time and 20 remain before they are thrown through one of the openings 16. However, there is a big one When the number of openings is present, sorting occurs to a considerable extent when the material is moved over the electrodes.

According to FIG. 1, each of the electrodes 14a and 14b is provided with a trough 72, the electrode 22 also being provided with the same device. Since the wells 72 are made of dielectric material, although these wells hang down towards the electrode 12, the electrostatic field is not adversely increased. Furthermore, the electrodes 14 a and 14 b are electrically isolated from one another by the arrangement of an insulating tub, so that different potentials can be applied. In this way, the electrode 14 α can be used to separate a particular fraction from the original material, while the electrode 14 b is available for the separation of another fraction, only by the fact that the electrode 14 b, for example, a higher direct current potential with respect to the electrode 12 has than the electrode 14 a.

From the F i g. 2 and 3 it can be seen that each trough 72 is provided with a lateral flange 74 which is attached to the electrode 14b by means of a number of rivets 76. As mentioned earlier, because the tubs are made of insulating or dielectric material, such as plastic, they do not distort the electrostatic field by drooping as a metallic tub would.

In the embodiment shown, the tub 72 connected to the electrode 14 a discharges the material into a chute 78 which is attached to one side of the frame 10. Since the tub has the shape of an angle when seen from above, another such slide is provided on the opposite side of the frame, the other tub having the same equipment but not shown. It should also be mentioned here that in practice the upper electrode 22 would be assigned a similar trough. In any case, it can be seen that the material thrown onto the upper side of the electrodes 14 a and 14 b is obtained in a separated state with the aid of the trays 72. In the same way, the material coming onto the electrode 22 is kept separate from the material remaining on the electrode 20.

Assuming that the electrode is used 146 to deposit a specific fraction of material, must in the electrode 14 of each lifting or high jumping α of the particles which have been thrown up α on this electrode 14 can be avoided in the region of the tub 72, as some Particles have enough momentum to jump over the tub onto the electrode 14 b , on which a fraction with different properties is collected, whereby this other fraction is falsified. The situation with electrode 14b and its trough 72 would be even more important, since any jumping up of the particles on the latter electrode in the area of the trough of that electrode would cause some particles to jump out over the trough and onto electrode 12 fall behind. Such a remixing of the material cannot of course be tolerated.

To explain these relationships, refer to FIG. 4, in which a sequence of arrows 80 indicates one possible path that the material from the electrode 14b is likely to follow. It is quite possible that a sufficient number of particles will be lifted up and propelled forward so that, instead of falling into tub 72, they will jump over the tub and fall back onto lower electrode 12 as electrode 14 does b is the last. This process is of course highly undesirable and the primary object of the invention is to correct or eliminate it.

In order to eliminate this aforementioned disadvantage, the invention envisages one in this endangered area arranged braking electrode 82 before. This electrode consists of a rod or rod 84 which is supported somewhat above the electrode 14 δ by a plurality of upstanding metallic posts 86. on Due to the presence of the braking electrode 82, the electrode 20 can be quite close to the electrode 14 δ be arranged because the intense field that would otherwise be due to the sharp edge at the outlet end of the

Electrode 14 would occur b, of this brake electrode 82 from the overlying to the next electrode 20 instead of the electrode 14 b extending to said electrode 20th Accordingly, the material migrating on the upper side of the electrode 14 b does not get into the above-mentioned intense field extending upwards from the braking electrode to the electrode 20, but migrates under the strong field, since the rod 84 lies slightly above the electrode 14 b. To emphasize the effect, FIG. 4 shows the device without the braking electrode 82, while in FIG. 5 shows the brake electrode. From FIG. 5 it can therefore be seen that the material on the electrode 14 b only migrates over this electrode and under the braking electrode 82 and immediately falls into the trough 72 when it reaches the outlet end of the electrode 14 b due to its gravity. There is no likelihood that material will jump out of the tub, as is the case with a missing brake electrode. Therefore, no material falls on the electrode 12, and there is also no mixing or remixing of the relevant materials.

From the above description of the processes at the electrode 14 b (FIGS. 4 and 5) with and without a braking electrode 82, the reason for the arrangement of a further braking electrode 82 in the vicinity of the trough 72 of the electrode 14 α is easy to see. Since the brake electrodes on both electrode plates 14 a and 14 b are equal to each other and bear the same reference numerals, the description of the α to the electrode 14 associated brake electrode is unnecessary, since their purpose is to prevent particles on the tray away to the electrode 14 b instead of jumping onto the electrode 12 as in the case of the braking electrode which is described in detail and which belongs to the electrode 14 b .

Depending on the way in which the discharge from the electrodes takes place, the braking electrode 82 for the lower electrode of a single pair of electrodes or for the lower electrode of two a number of electrodes arranged vertically one above the other can be used with advantage. In In any case, the braking electrodes reduce the field intensity at the discharge edges of the electrodes to which they are attached and prevent undesired upward movement between the electrodes, which should work together.

The F i g. 6 and 7 show an arrangement in which a braking electrode is assigned to the lower of two electrode plates. In this case it is assumed that it is the outermost end or the final discharge station of two electrodes 90 and 92, the lower electrode 90 corresponding to the previously described electrode 12 and the upper electrode 92 corresponding to the electrode 14 a or 14 b and their corresponding Function. In order to allow the raised material to reach the top of the electrode, it is provided with openings 94 which are surrounded by upstanding collars 96. Like the aforementioned electrodes 12 and 14, the present electrodes are connected to a source of electrical potential via conductors 98 and 100, with conductor 98 leading to ground and conductor 100 leading to a negative high voltage source.

A transverse trough 102 is attached to the lower electrode 90, while another trough 104 is attached Distance under the upper electrode 92 is arranged. These tubs or containers can be of any Be a shape that depends primarily on the shape of the discharge edges of the electrodes 90 and 92. For the purposes of the description it is assumed that the discharge edges are straight and the tubs, seen from above, are rectangular.

From Fig. 6 it can be seen that some particles, which should fall into the tub 102 per se, this

ίο don't just do that and use this tub instead skip and either fall into or possibly miss tub 104, but in each Trap get lost. Accordingly, the desired directions of movement became following particles indicated by arrows with reference numerals 106 and 108, during undesired directions of movement were designated with 110.

The trajectory 110 is avoided by attaching a braking or suppression electrode 112 in the form of a rod or a strip with an angular cross-section. As with the previous ones Electrodes described can also be carried by a plurality of metal posts 114, the protrude upward from the electrode 90. The braking member 112 influences or modifies the electrostatic Field in this district so that the particles which follow path 110 in FIG. 6 describe instead merge with those who walk path 106, the merged stream being easy under the electrode 112 without jumping up, as in FIG. 6 shown, wanders through. To this In this way, the particles destined for the tub 102 and those destined for the tub 104 become without harmful mixing and collected without loss due to missing tub 104.

Although only a relatively limited number of electrodes have been shown, it goes without saying that additional electrodes are used depending on the circumstances and the number of separations desired will. For this reason, the device can only be given an exemplary embodiment has been used extensively for sorting granular material.

Claims (8)

Patent claims: 1. Electrostatic precipitator with spaced apart upper and lower electrodes, wherein the upper electrode has a number of openings through which material, attracted from the lower electrode to the top of the upper electrode can reach, with a conveyor for material transport over the lower electrode and with a voltage source that maintains a potential difference between the electrodes, characterized in that one of the electrodes at the discharge end is provided with an auxiliary electrode (82, 84, 112) to which a voltage is applied. 2. Electrostatic precipitator according to claim 1, characterized in that the potential on the auxiliary electrode is approximately equal to the potential on the associated electrode (14 b) . 3. Electrostatic precipitator according to claim 1 or 2, characterized in that the Auxiliary electrode is arranged over the discharge end of the associated electrode. 4. Electrostatic precipitator according to claim 1, 2 or 3, characterized in that the auxiliary electrode above the associated electrode by upright metallic parts (86, 114) is supported. 5. Electrostatic separator according to one of claims 1 to 4, characterized in that that the discharge end with a trough (72) for receiving from the auxiliary electrode there guided particles is provided. 6. Electrostatic precipitator according to one of the preceding claims, characterized in that that the auxiliary electrode (112) has an angular cross section. 7. Electrostatic precipitator according to claims 1 to 6, characterized in that the discharge end of the respective upper electrode over the discharge end of the lower electrode in Direction of conveyance protrudes. 8. Electrostatic precipitator according to claims 1 to 7, characterized in that the wells are made of a dielectric material. Considered publications:
German Patent Nos. 687 595, 875 482;
British Patent No. 599 908. 1 sheet of drawings 409 510/99 2.64 © Bundesdruckerei Berlin