EP0265451A1

EP0265451A1 - Electrostatic separation device.

Info

Publication number: EP0265451A1
Application number: EP87902057A
Authority: EP
Inventors: Dumitru Cucu
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-03-27
Filing date: 1987-03-26
Publication date: 1988-05-04
Anticipated expiration: 2007-03-26
Also published as: DE3762810D1; WO1987005830A1; DE3611019A1; EP0265451B1

Abstract

Dispositif de séparation électrostatique à deux niveaux se présentant sous la forme d'une cartouche filtrante électrostatique (6) incorporant un agent de neutralisation et pouvant être logée dans un boîtier (1) tubulaire ou rectangulaire. Le dispositif est formé d'électrodes en forme de lamelles (7) auxquelles on applique des potentiels différents et qui sont séparées par des films isolants (8). L'ionisation des particules à séparer s'effectue via une source d'UV et/ou dans l'espace entre une électrode de grille (4) mise à la terre et le bord de l'électrode en lamelles (7), à laquelle on applique une forte tension, une densité ionique élevée étant créée dans ledit espace. Les particules ionisées sont séparées dans la cartouche filtrante (6) électrostatique formant le collecteur. Au niveau de la sortie du gaz de la cartouche filtrante (6) électrostatique, une décharge par effet de couronne présentant les deux polarités ioniques se produit entre les électrodes mises à la terre et les électrodes en lamelles (7) qui sont soumises à une tension élevée (9), ce qui permet d'assurer le fonctionnement d'une zone de neutralisation (17) pour le courant de gaz filtré.Two-level electrostatic separation device in the form of an electrostatic filter cartridge (6) incorporating a neutralizing agent and which can be housed in a tubular or rectangular housing (1). The device consists of lamellar electrodes (7) to which different potentials are applied and which are separated by insulating films (8). The ionization of the particles to be separated is carried out via a UV source and / or in the space between a grounded gate electrode (4) and the edge of the strip electrode (7), to which a high voltage is applied, a high ion density being created in said space. The ionized particles are separated in the electrostatic filter cartridge (6) forming the collector. At the gas outlet of the electrostatic filter cartridge (6), a corona discharge with two ionic polarities occurs between the grounded electrodes and the strip electrodes (7) which are subjected to a voltage high (9), which ensures the operation of a neutralization zone (17) for the filtered gas stream.

Description

Electrostatic separator

The prior art includes two-stage electrostatic precipitators. They have been known for around 45 years and were developed for the purpose of achieving high degrees of separation for solid particles, aerosols or under iconic drops from the gas stream.

In the first stage of a known electrostatic filter, the solid particles are charged by ions of one polarity with the aid of a so-called ionizer stage.

The ionizer consists of electrodes, also called spray electrodes, in the form of wires or tips on which the electrical field lines are concentrated. These electrodes are arranged between the counter electrodes, consisting of parallel plates. A plasma layer forms around the spray electrodes. The ions of the plasma layer with the same polarity as the spray electrodes migrate to the counter electrodes. The solid particles that flow through this ion rain are electrically charged because the ions are fixed on their surface.

In the second stage, the solid particles are pulled out of the gas flow and fixed on the plates of a collector. The collector consists of separating plates which are at different potentials under high voltage and between which an electric field is generated. When flowing through the collector, the electrically charged solid particles are eliminated from the gas flow thanks to the electrostatic forces which act on the charged solid particles in the electrical field of the collector and are deposited on the collector plates.

In the patents US 2 579 441, US 2 502 560, US 3 798 879, US 2 504 430, DE 19 55 692, DE 12 45 328, DE 23 46 196, DE 11 67 799, which show the current state of the art Various known versions of two-stage electrostatic filters are shown.

All described electrostatic precipitators are, without exception, complicated and expensive designs with a weight of sometimes approx. 30 kg, and all electrostatic filters are subject to a complicated manufacturing technology. The object of the present invention is to improve the current state of the art and is intended to manufacture electrostatic filters for the filtration of solid particles or droplets from gas or air with a higher degree of separation, in particular for submicron particles, ie in the range of 0.01 / um to l, um particle sizes.

The advantages of the present invention are numerous. An advantage is that such an electrostatic filter is, for example, much cheaper to manufacture, about 10-20 times cheaper than a classic two-stage electrostatic precipitator for the same amount of gas flow to be filtered.

The design of this new electrostatic precipitator is very simple, with little manufacturing. ^; Effort can be automated.

The embodiment of the present invention allows the distances between collector electrodes to be reduced to the smallest distances, on the order of approximately 1 mm. In this way the highest degrees of separation are achieved. The realization of such small distances between the electrodes and the collector plates is impossible with the previously existing electrostatic filters with metal plates.

The described electrostatic filter can be operated with only a single high voltage supply. The electrostatic filter described in the invention has a minimal weight. It can be about 20 times lighter than a classic electrostatic filter because conductive foils with a low weight and a small thickness, for example 0.03 mm, are used as electrodes.

Another advantage is that the separating device according to the invention can be inserted into any tubular system, whether or not already on site. In addition, the pluses and minusions generated by the electrodes at the outlet of the gas flow from the electrostatic filter cartridge neutralize the electrical charge in the room air.

By using electrodes with wider foils, the degree of separation of the filter can be increased in a very simple manner. By this measure, i.e. Extension of the cylindrical filter cartridge, separation levels from the area of HEPA filters with 99.99% separation rate for the smallest particles are achieved. An increase in the degree of separation can also be produced by increasing the diameter of the spiral or cylindrical electrostatic filter cartridge and by increasing the high voltage.

Another advantage is that the electrostatic filter cartridge, because it is inexpensive to manufacture, like any mechanical filter made of porous or fibrous medium when loaded with dust, can be fitted with a new cartridge and replaced like any other mechanical filter. In this way, the filter cartridge can be replaced as "hazardous waste" when the filtered aerosol is dangerous or toxic to the environment. As a result, the current existing situation can be eliminated, in which electrostatic precipitators are cleaned and the toxic dust that is washed out of the electrostatic precipitator gets into the waste water.

Thanks to its very low manufacturing price and its "special waste" properties, this new type of electrostatic precipitator can be used wherever radioactive particles have to be filtered. For this reason, this new electrostatic filter is an ideal air filter for the nuclear industry, where radioactive particles or aerosols have to be filtered.

Current electrostatic precipitators cannot be used to filter radioactive particles. For this purpose, mechanical filters with a large pressure loss and large energy consumption must be used. Another important advantage of this new type of electrostatic filter proposed here is the separation of the electrodes from the insulating foils, so that conductive particles can also be filtered, which is not suitable in most cases with the electrostatic filters offered by the current state of the art.

The use of this invention in the filtration of an oil mist is particularly favorable because the electrode edges on the outlet side of the gas flow are separated from the insulating foils, whereby the electric field lines no longer concentrate so intensely on the edges and the flowing oil film can no longer be transformed into very fine oil drops by secondary production. This secondary production of very fine liquid aerosol is a very unfavorable phenomenon in the current electrostatic filters. On the other hand, with this invention, oil mist or any other mist with the highest degree of separation can be filtered with the electrostatic filter.

Even very aggressive mists such as acids and alkalis can be separated economically with suitable materials. Water vapor and droplets can also be separated by means of sufficiently large widths for the insulating foils.

A further advantage of this invention is that the price of the separating device can be reduced even further by using insulating foils which have a conductive layer on one of their sides, or by the foils having special electrical polarization properties or magnetic properties exhibit.

These properties increase the separation effect for the particles or aerosols.

A further increase in the degree of separation can can also be achieved if a centrifugal movement is impressed on the gas flow before it enters the collector, so that the adhesion of the particles to the foils is favored.

Further details and features of the present invention are described in more detail below in conjunction with the drawings.

1 shows an electrostatic separating device with a UV light source 2, with a grid electrode 4 and an electrostatic filter cartridge 6, consisting of spiral-shaped insulating foils 8 and foil electrodes 7, applied to a high-voltage source 9, and which in a tubular housing 1 is mounted.

2 shows a sectional view of a spiral-shaped electrostatic filter cartridge 6 in the housing 1.

3 shows a zigzag-shaped insulating film 8 between the film electrodes 7 and the housing 1.

4 shows a smooth insulating film 8 with zigzag-shaped film electrodes 7, installed in the housing 1.

5 shows a possibility of the invention, in which the insulating foils 8 have a zigzag shape and the foil electrodes 7 have been placed one on top of the other, whereby one rectangular electrostatic filter cartridge 6 is formed.

6 shows a possibility of the invention, in which the insulating foils 8 are laid flat and the foil electrodes 7 are placed on top of one another in a zigzag shape, whereby a rectangular electrostatic filter cartridge 6 is created.

FIG. 7 shows a further possibility of folding the insulating film 8 between the film electrodes 7 and the housing 1.

FIG. 8 shows a reversal of FIG. 7, the insulating foils 8 being smooth and the foil electrodes 7 being folded.

9 shows a further possibility of folding the insulating films 8.

10 shows an embodiment of an electrostatic precipitator, in which the insulating foils 8 and the foil electrodes 7 arranged in a cylindrical, coaxial manner form an electrostatic filter cartridge 6 which has been installed in a housing 1.

11 shows an embodiment of the invention in which the electrostatic filter cartridge 6 can be cleaned by an automatic washing device with an ultrasound generator 16, by means of a filler tube 11, a cleaning liquid 10 flows in, which can flow out of the drain valve 12 after use.

12 shows an embodiment of the invention in which the gas flow in the core area and in the edge area of the electrostatic filter cartridge 6 is passed through a gas flow guide 13.

FIG. 13 shows an embodiment of the invention in which a liquid 15 is sprayed onto the electrostatic filter cartridge 6 by means of a nozzle 14, whereby a wet separator is created.

14 shows an embodiment of the invention in which the electrostatic filter cartridge 6 is formed from two spiral-shaped insulating foils 18, 19, each of which has a conductive layer on one of its sides.

15 shows an embodiment of the invention in which the ionization stage is separated from the collector stage and a spiral-shaped spray electrode 20 discharges corona in the direction of one or two grid electrodes 4.

1 shows the functional principle of the present invention. A gas stream to be cleaned flows through a housing 1 in the direction of the arrow and is irradiated by the UV rays 3 of a UV source 2. After that, he is through a grid electrode 4 is conducted and ionized in the ionizer zone 5 by an ion rain. Positive or negative ions are generated in the ionizer zone 5. They arise from a corona discharge from the spiral edge, which is located under high voltage potential 9.

From the first ionization zone, consisting of the UV source 2, and the second ionization zone 5, where the further ionization of the gas stream takes place by so-called ionic bombing, the particles in the gas stream flow into a third zone, the so-called electrostatic filter cartridge 6. This contains the spiral foil electrodes 7, which are applied to differently polarized potential and are separated by insulating foils 8. In Fig. 1 it can clearly be seen that the insulating foils 8 extend beyond the foil electrodes 7 in their length, producing the so-called insulation spacing.

The particles in the gas stream which are electrically charged after the ionization stage are pulled out of the gas stream thanks to the electrostatic forces in the space between the film electrodes 7 and deposited on the surface of the grounded film electrode and also on the surface of the strongly polarized insulating films 8 .

A so-called fourth stage is formed by a neutralizer 17. The neutralizer zone 17 is on the gas outlet side of the electrostatic filter cartridge 6 formed. The fourth stage is formed by the edges of the spiral foil electrodes 7, which generate a corona discharge between them by concentrating the field lines. As a result, ions of both polarities are generated, which in this way bring about an electrical neutralization of both the gas flow and the objects possibly located in the space into which the gas flow flows.

It is also shown that the insulating foils 8 protrude from the foil electrodes 7 and that a necessary insulating distance is achieved. 1 that a spiral-shaped insulating film 8 is inserted between the grounded housing 1 and the film electrode 7 connected to the high-voltage potential 9, which isolates the electrostatic filter cartridge 6 from the housing 1.

The particles can also be charged on the gas inlet side in that the corona discharge does not take place between the edge of a foil electrode and the grid electrode, but between the edges of two foil electrodes lying at different potential. The grid electrode can then be omitted. 11a

In Fig. 2 the spiral design of the electrostatic precipitator is shown. The sectional view shows the top view of the electrostatic filter cartridge 6. It can clearly be seen that the ends of the insulating film 8 protrude beyond the ends of the film electrodes 7, so that there is a safe insulation distance. It can also be seen that an insulating film 8 is inserted between the housing 1 and the film electrode 7, which has been applied to a positive high-voltage potential 9.

12th

In Fig. 3 the layered structure of an electrostatic filter cartridge 6 is shown in a sectional view. In this case, the zigzag films are insulating films 8. The film electrodes 7 are smooth films. It can also be clearly seen here that an insulating film 8 is inserted between the outer film electrode 7 and the housing 1.

4 shows the sectional structure of an electrostatic filter cartridge 6 in a sectional view, in which case the foil electrodes 7 are folded in a zigzag shape and the insulating foils 8 are smooth foils. Here, too, an insulating film 8 is inserted between the housing 1 and the outer film electrode 7.

A further possibility of the invention is shown in FIG. In this case, zig-zag insulating foils 8 are placed on top of one another in layers with flat foil electrodes 7. In this way, rectangular electrostatic filter cartridges 6 can also be produced.

6 shows a possibility corresponding to that already described in FIG. 5. Here, zigzag-shaped foil electrodes 7 are inserted between flat insulating foils 8, so that, for example, rectangular electrostatic filter cartridges 6 are created. 13

A further embodiment of the folded insulating films 8 is shown in FIG. 7. The film was folded round and, as already described in FIG. 3, wrapped between the film electrodes 7.

In FIG. 8, similar to FIG. 4, a film electrode, which is folded round, is processed into an electrostatic filter cartridge 6.

9 shows a further possibility of a type of folding. Layer structure and function of the electrostatic filter cartridge 6 are retained.

10 shows an embodiment in which the foil electrodes 7 and the insulating foils 8 represent cylindrical bodies which, when placed coaxially one inside the other, form an electrostatic filter cartridge 6. In this case too, an insulating film 8 is inserted between the outer film electrode 7 and the housing 1.

11 shows a possibility in which automatic cleaning or regeneration of the electrostatic filter cartridge 6 is possible. If the electrostatic filter cartridge 6 has to be cleaned of attached dust or aerosols, the filtration of the gas stream and the supply of electrical energy via the high-voltage potential 9 must be interrupted. Once this has been done, the U-shaped housing 1 can be 14

tubes 11 are filled with a cleaning liquid 10 so far that the electrostatic filter cartridge 6 is flooded. After this process, an ultrasound generator 16 is switched on, which vibrates the cleaning liquid 10. The vibrations separate the deposited particles from the film electrodes 7 and the insulating films 8. The detached particles sink in the cleaning liquid 10 in the direction of the drain valve 12. By means of the drain valve 12, the cleaning liquid 10 with the particles can be discharged and, if necessary, renewed.

With this device, even in the case of filtration of an oil mist or other nebulous liquid, the filtered material can sink down, collect in the lower part of the U-shaped housing 1 and be drained from there, so that the filtered liquid aerosols can be recovered.

FIG. 12 shows an embodiment in which the gas stream flowing into the housing is passed through gas flow guides 13 which are arranged directly in front of the electrostatic filter cartridge 6. This makes it possible to direct the gas flow in such a way that it cannot flow through the intermediate space between the housing 1 and the electrostatic filter cartridge 6. The same also applies to the core area of the electrostatic filter cartridge 6. The gas flow guides 13 15

are advantageous because the core area and the edge area are zones with a lower degree of separation.

13 shows an electrostatic filter device in which a liquid 15 is sprayed onto the electrostatic filter cartridge 6 by means of a nozzle 14. This creates a wet electrostatic precipitator with a high degree of separation.

14 shows an embodiment in which the electrostatic cartridge 6 is formed only from two foils, one of which is smooth and the other is zigzag-shaped. Each of these foils is conductive on one side, so that when it is wound up, the two conductive layers, which are at different potential, are separated throughout the cartridge by an insulating layer.

An embodiment is shown in FIG. 15 in which the ionizer is separated from the collector. Here, the ionizer is formed from a spiral spray electrode 20, which can be the edge of a foil, a fine metal wire or a plurality of tips, which discharges the corona with respect to one or two grid electrodes 4 and thereby forms one or two ionization zones 5. This ionizer is designed such that it can be supplied with current of one polarity, thereby generating ions of this polarity, or with alternating current, thereby generating ions of both polarities.

Claims

16 patent claims

1. Two-stage electrostatic separating device with an ionizer and a collector for separating solid particles, drops or aerosols, consisting of at least two wound foil electrodes (7) connected to different potential, which are separated from one another by insulating foils (8) are, which ensures the passage of a gas flow through the spaces between the electrostatic filter cartridge (6) thus formed, characterized in that the edge of a foil electrode (7) on the gas inlet side is connected to a high-voltage potential (9) and counteracts a corona discharge the edge of another foil electrode (7) or a grid electrode (4), which have a potential difference to it, arises, as a result of which an inflowing gas stream gets a high ion density, thus forming an ionization zone for the gas stream before it enters the electrostatic filter cartridge (6) , and that at A corona discharge occurs on the gas outlet side of the electrostatic filter cartridge (6) between the edges of both foil electrodes (7), ions of both polarities being generated and thereby a neutralization zone (17) being formed for the outflowing gas stream. 17

2. Separating device according to claim 1, characterized in that the edge insulating films (8) protrude the edges of the film electrodes (7) on the gas inlet and the gas outlet side by at least 5 mm, and that the beginnings and ends of the wound insulating films (8) exceed those of the foil electrodes (7) by at least 5 mm.

3. Separation device according to claim 1 or 2, characterized in that there are two gas flow guides on the gas inflow side of the electrostatic filter cartridge (6)

(13) are located so that the gas flow cannot pass through the area between the electrostatic filter cartridge (6) and the housing (1) and the core area of the electrostatic filter cartridge (6) when it enters and passes through.

4. Separating device according to one of claims 1 to 3, characterized in that the foil electrodes (7) are zigzag-shaped and are separated by two insulating foils (8) which are placed one on top of the other and spirally wound together to form a compact spiral-shaped electrostatic

Form the filter cartridge (6). 18th

5. Separating device according to one of claims 1 to 4, characterized in that on one of the edges of the foil electrodes (7) of the gas inlet side of the electrostatic filter cartridge (6) tips are formed which generate ions by corona discharge.

6. Separating device according to one of claims 1 to 5, characterized in that the electrical charging of the particles is carried out in a separate ionizer, the two film electrodes (7), which are separated by the insulating films (8), only one Represent collector pack.

7. Separating device according to one of claims 1 to 6, characterized in that the electrostatic filter cartridge (6) is installed in a cylindrical or rectangular housing (1).

8. Abscheidevorriσhtung according to any one of claims 1 to 7, characterized in that the particles in the gas stream are irradiated with ultraviolet rays (3) before they enter the electrostatic filter cartridge (6).

9. Separating device according to one of claims 1 to 8, characterized in that the film electrodes (7) consist of a conductive plastic. 19

10. Separating device according to one of claims 1 to 9, characterized in that between the foil electrodes (7) and the insulating foils (8) by beads, waves, threads or other deep-drawn shapes, which are located on the foils wound together, a distance is formed.

11. Separating device according to one of claims 1 to 3.5 to 10, characterized in that the foil electrodes (7) and the insulating foils (8) represent axially arranged individual cylinders of different diameters, which are placed one inside the other an electrostatic filter cartridge (6) form.

12. Separation device according to one of claims to 3.5 to 10, characterized in that the foil electrodes (7) and the insulating foils (8) lie one above the other in a planar manner.

13. Separating device according to one of claims 1 to 12, characterized in that the electrostatic filter cartridge (6) and / or the ionizer zone (5) is installed in a U-shaped tube which can be filled with a cleaning liquid (10) with which floods the electrostatic filter cartridge (6) and can be cleaned, the tube on its lower curved side having a drain valve (12) for exchanging the cleaning liquid (10) 20th

14. Separating device according to claim 13, characterized in that an ultrasonic generator (16) is located inside or outside the U-shaped tube in the region of the electrostatic filter cartridge (6), which transmits its vibrations to the electrostatic filter cartridge (6), whereby the entire mass of the cleaning liquid (10) receives the vibration of the ultrasonic generator (16) and cleaning of the electrostatic filter cartridge (6) is initiated.

15. Separating device according to one of claims 1 to 14, characterized in that the foil electrodes (7) are supplied with DC voltage.

16. Separating device according to one of claims 1 to 14, characterized in that the foil electrodes (7) are supplied with AC voltage.

17. Separating device according to one of claims 1 to 16, characterized in that the insulating films (8) consist of a material polarizing in an electric field.

18. Separating device according to one of claims 1 to 17, characterized in that there is a nozzle in the region of the gas inlet into the electrostatic filter cartridge (6) through which the electrostatic 21

Filter cartridge (6) is moistened with a liquid (15) so that a wet electrostatic filter is created.

19. Separating device according to one of claims 1 to 18, characterized in that the outer film electrode (7), which encloses the entire electrostatic filter cartridge (6), is applied to a high electrical potential and from the housing (1) by an insulating film (8 ) is isolated.

20. Separating device according to one of claims 1 to 19, characterized in that the electrostatic filter cartridge (6) is formed from at least two insulating films, each of which has a conductive layer on only one of its sides, one (19) of which is zigzag ¬ shaped and the other (18) is even, so that there is an insulating layer in the filter cartridge (6) between the two conductive layers.

21. Separating device according to one of claims 1 to 20, characterized in that the film electrodes and / or the insulating films (7,8, -18,19) have magnetic properties which additionally contribute to the separation of the particles. 22

22. Separating device according to one of claims 1 to 21, characterized in that a centrifugal motion is impressed on the gas flow before entry into the filter cartridge (6), so that it enters the filter cartridge (6) with a circular centrifugal movement.

23. Separating device according to one of claims 1 to 22, characterized in that the ionization stage is separated from the collector stage and is formed from a spiral or wave-shaped spray electrode (20) which is under high voltage and corona in the direction of the gas flow discharges one or two grounded grid electrodes between which it is located.

24. Separating device according to one of claims 1 to 23, characterized in that on the gas flow outlet side of the electrostatic filter cartridge (6) between the edge of only a single foil electrode (7) and a grid electrode which is under alternating high voltage, a corona -Discharge takes place, whereby ions of both polarities are generated.