SPRAY ELECTRODE AND ELECTROFILTER WITH SUCH A SPRAY ELECTRODE

Description

[0001] The invention relates to a spray electrode for an electrostatic precipitator, formed from a sheet metal strip extending in a plane with a longitudinal axis, which is formed at its longitudinal edges with spray tips projecting transversely to the longitudinal axis, wherein the spray tips each have a foot and a tip section and the foot sections run in the plane and the tip sections are arranged at opposite angles to the plane at both longitudinal edges.

[0002] Electrostatic precipitators with spray electrodes are used, for example, to purify gas streams. Their operation is based on the electrostatic charging of particles, aerosols, and gases. A high-voltage field of, for example, 10 to 15 kV is applied between several adjacent, usually plate-shaped, collecting electrodes and spray electrodes. This ionizes the particles, aerosols, and gases contained in the gas stream at the spray electrodes, causing them to subsequently be deposited at the collecting electrodes. An example of such a spray electrode for an electrostatic precipitator is described in AT 2 55590 B1.

[0003] The applicant of the present patent application has also been marketing electrostatic precipitators under the trade name Ultravent® for many years, featuring generic spray electrodes formed from a sheet metal strip extending in a plane, with spray tips projecting transversely to the longitudinal axis along its longitudinal edges. Such spray electrodes formed from a flat sheet metal section without angled tip sections are also disclosed in CN 111 437 996 A, WO 2013 / 065906 and US 7 942 952 B2.

[0004] Spray electrodes of this type are disclosed, for example, in EP 0 437 849 A1 and EP 0 629 449 A2. They have tip sections with split tips that extend in opposite directions from the plane. Similar designs are also found in JP 2000 197833 A, DE 12 01 816 B, US 4 514 195 A and EP 1 439 913 A1.

[0005] During operation of an electrostatic precipitator, the filtered particles accumulate on the surface of the collecting electrodes and also on the spray electrodes, preferably in the area of ​​the spray tips, forming a coating that gradually impairs the efficiency of the electrostatic precipitator, thus necessitating regular cleaning of these surfaces and the spray tips. This is usually done using a cleaning device which, as needed, sprays a liquid cleaning agent, for example, hot water under pressure, onto the surfaces of the collecting electrodes and the spray electrodes to remove the deposits and encrustations.A recurring problem is that the spray tips, due to their small surface area and their parallel arrangement to the collecting electrodes through which the cleaning fluid jet passes, cannot be adequately cleaned, as the cleaning jet has difficulty reaching the spray tips. This appears to be an area for improvement.

[0006] The object of the present invention is to further develop a spray electrode of the type mentioned above in such a way that improved cleaning and also improved ionization performance can be achieved with minor structural modifications.

[0007] According to the invention, this problem is solved by designing a spray electrode according to the features of claim 1.

[0008] Advantageous embodiments and further developments of the invention are the subject of the dependent claims.

[0009] According to the invention, it was surprisingly found that improved cleaning and, moreover, improved ionization performance of the spray electrode can be achieved by having all tip sections of a longitudinal edge inclined by the same angle in the same direction from the plane of the sheet metal strip and the base section, and by having the tip sections of the opposite longitudinal edge inclined by the same angle in the opposite direction from the plane of the sheet metal strip and the base section.

[0010] In the embodiment proposed according to the invention, the spray tips are arranged at an angle to the plane in which the spray electrode extends and protrude uniformly beyond the plane, so that a spray jet from a cleaning device, which is directed between the collecting electrodes towards the spray electrode which usually extends parallel to the collecting electrodes, strikes the correspondingly inclined spray tips, which results in a significantly improved cleaning effect, particularly at the free end of the spray tips.

[0011] The inclined arrangement of the tip sections according to the invention further reduces the distance to the adjacent precipitation electrodes compared to spray tips that extend only in the plane, thereby enabling a stronger electric field and higher ionization power to be achieved between the spray tips and the precipitation electrodes.

[0012] According to one proposal of the invention, the angle at which the tip sections are inclined relative to the plane is selected from a range of 5° to 25°.

[0013] It is further proposed that the spray tips be integrally formed from the sheet metal strip, with approximately U-shaped gaps between adjacent spray tips. Such a configuration of the spray electrode can be achieved, for example, by stamping or laser cutting a corresponding sheet metal strip that was originally rectangular in shape, and requires only minimal manufacturing effort.

[0014] For uniform ionizing performance, it is further proposed that the spray tips have equal distances from each other along the longitudinal edges of the spray electrode, and it is also preferred that all spray tips are uniformly shaped.

[0015] It is further proposed that the spray tips on the opposite longitudinal edge are arranged opposite a free space between two adjacent spray tips, i.e. the spray tips along one longitudinal edge are arranged with a regular division and the spray tips on the opposite longitudinal edge are offset by half the division length to the spray tips of one longitudinal edge and are also arranged regularly.

[0016] Finally, according to the invention, the spray electrode can also have spray tips pointing towards the longitudinal axis on the end faces in order to deliver good ionizing performance in this area as well.

[0017] An electrostatic precipitator provided within the scope of the invention is characterized by a design with at least one such spray electrode as described above.

[0018] In particular, the electrostatic precipitator can have a plurality of plate-shaped collecting electrodes and spray electrodes arranged adjacent to and parallel to the collecting electrodes, and a cleaning device for spraying a cleaning fluid onto the surfaces of the collecting and spray electrodes.

[0019] Further embodiments and details of the invention are explained below with reference to the drawing illustrating an exemplary embodiment. The drawing shows: Figure 1 shows a side view of a spray electrode according to the invention; Figure 2 shows the spray electrode according to the invention. Figure 1 in a perspective view; Figure 3 the view of the spray electrode in the direction of the longitudinal axis; Figure 4 a part of an electrostatic precipitator with a spray electrode according to Figure 1 .

[0020] From the Figures 1 to 3A spray electrode 1 for an electrostatic precipitator for cleaning a gas stream, which will be explained in more detail below, is visible.

[0021] The spray electrode 1 is made from an electrically conductive metal sheet in the form of a sheet strip 10, for example by means of laser cutting, wherein the sheet strip extends in a plane along the longitudinal axis L, which is aligned with the drawing plane. Fig. 1 The longitudinal axis L coincides. On both sides of the longitudinal axis L, spray nozzles 11 are formed regularly and transversely to the longitudinal axis L by removing essentially U-shaped free spaces 12 between the spray nozzles 11 from the sheet metal strip 10 during manufacturing. All spray nozzles 11 are arranged with identical geometry and at equal intervals along the longitudinal axis L.

[0022] Comparing the figures shown in the representation according to Figure 1With upwardly projecting spray tips 11 on one longitudinal edge and downwardly projecting spray tips 11 on the opposite longitudinal edge, it can be seen that a spray tip 11 on one longitudinal edge and a free space 12 on the opposite longitudinal edge are opposite each other, i.e. the spray tips 11 arranged with regular divisions are offset by half the division length on each opposite longitudinal edge.

[0023] Furthermore, the spray electrode 1 has a mounting opening 13 at each of its two ends for mounting in the electrostatic precipitator and a further spray tip 11 pointing in the longitudinal direction L at each end.

[0024] As can be seen in particular from the representations according to Figures 2 and 3As can be seen, the spray nozzles 11 are constructed such that, starting from the central sheet metal strip 10, they first have a base section 110 extending in the plane spanned by the sheet metal strip 10, which projects integrally from the sheet metal section 10 in the region of its longitudinal edge, to which a nozzle section 111 adjoins at its free end, which is arranged at an angle (α) relative to the plane spanned by the sheet metal strip 10 and the base section 110. In the illustrated embodiment, the angle (α) is, for example, 10°.

[0025] Furthermore, it can be seen that along one longitudinal edge all tip sections 111 are inclined by the same angle (α) in the same direction from the plane of the sheet metal strip 10 and the foot section 110, while the tip sections 111 along the opposite longitudinal edge are inclined by the same angle (α) in the opposite direction from the plane of the sheet metal strip 10 and the foot section 110.

[0026] Such a spray electrode 1 can be constructed in a manner known per se as shown in the Figure 4 They can be incorporated into an electrostatic precipitator, which, for example, serves to purify a gas stream G. For this purpose, a plurality of plate-shaped collecting electrodes 2 are held parallel to each other in a holder 4 in a manner known per se and not shown in detail here, so that the gas stream indicated by arrow G can be passed between the collecting electrodes 2 parallel to them.

[0027] It is understood that the electrostatic precipitator shown is only depicted in a partial section across its entire width, i.e., further arrangements of precipitation electrodes 2 and spray electrodes 1 arranged upstream in the gas stream G may be provided to the left of the drawing.

[0028] The collecting electrodes 2 comprise alternating parallel plates 20, 21, wherein the plates 21 and 22 are slightly shorter than the plates 21 and the shorter plates 21 can be connected to a high-voltage source (not shown) via a contact plate 30 and threaded rods 31. The parallel plates 20, on the other hand, are connected to an insulator tube 32 surrounding the threaded rods 31 and are grounded.

[0029] Spray electrodes 1 are arranged upstream of the precipitation electrodes 2 in the direction of flow, of which in the Figure 4Only one is shown. These spray electrodes 1 are also aligned parallel to the precipitation electrodes 2 in order to offer the least possible resistance to the gas flow G and are held in corresponding support rods 3, which pass through the mounting openings 13 and are electrically contacted and, like the plates 21, connected to the high-voltage source.

[0030] In a manner known per se, a high-voltage field is then applied to the spray electrodes 1 and the plates 21 to ionize the particles, aerosols, etc., carried in the gas stream G and deflect them onto the plates 20, whereupon they are deposited on the grounded plates 20. However, a gradually increasing coating inevitably forms on the plates 21 and the spray electrode 1, particularly in the area of ​​the spray tips 111. This coating impairs the performance of the electrostatic precipitator over time, so a cleaning fluid, such as hot water under pressure, is typically sprayed between the precipitation electrodes 2, for example vertically from top to bottom as indicated by arrows R, and onto the spray electrodes 1 using a cleaning device (not shown in detail here) to remove the surface deposits.

[0031] Due to the previously explained angulation of the tip sections 111 of the spray tips 11 by the angle (α), these are positioned, as can be seen from the Figure 4 visibly, slightly oblique to the liquid jet R of the cleaning device passing parallel through the free space between the precipitation electrodes 2, which is why adhesions on the tip sections 111 can be better detected and cleaned off.

[0032] Moreover, this inclined arrangement of the spray tips 11 in the area of ​​the tip sections 111 reduces the distance to the plates 20, which results in improved ionization performance.

[0033] It is understood that the directions for the gas flow G and the cleaning fluid R explained above and shown in the drawing are merely examples and can also be opposite or, for example, in a horizontal orientation.

[0034] The spray electrodes 1 described above can be used both in newly constructed electrostatic precipitators and as retrofit parts on existing electrostatic precipitators.

Claims

1. A spray electrode (1) for an electrostatic precipitator, formed from a sheet metal strip (10) extending in a plane and having a longitudinal axis (L), which is formed at its longitudinal edges with spray tips (11) projecting transversely to the longitudinal axis (L), wherein the spray tips (11) each have a root section and a tip section (110, 111) and the root sections (110) extend in the plane and the tip sections (111) are arranged at both longitudinal edges inclined in opposite directions by an angle (α) relative to the plane, characterized in that all tip sections (111) of one longitudinal edge are inclined by the same angle (α) in the same direction from the plane of the sheet metal strip (10) and the root section (110) and the tip sections (111) of the opposite longitudinal edge are inclined by the same angle (α) in the opposite direction from the plane of the sheet metal strip (10) and the root section (110).

2. The spray electrode (1) according to claim 1, characterized in that the angle (α) is about 5 to 25 °.

3. The spray electrode (1) according to any one of claims 1 or 2, characterized in that the spray tips (11) are integrally formed from the sheet metal strip (10) and free spaces (12) formed approximately in a U-shape are provided between adjacent spray tips (11).

4. The spray electrode (1) according to any one of claims 1 to 3, characterized in that the spray tips (11) have equal distances from one another along the longitudinal edges of the spray electrode (1).

5. The spray electrode (1) according to claim 4, characterized in that the spray tips (11) on the opposite longitudinal edge lie opposite a free space (12) between two adjacent spray tips (11).

6. The spray electrode (1) according to any one of claims 1 to 5, characterized in that spray tips (11) pointing in the direction of the longitudinal axis (L) are formed on the end faces.

7. An electrostatic precipitator comprising at least one spray electrode (1) according to any one of the preceding claims.

8. The electrostatic precipitator according to claim 7, comprising a plurality of plate-shaped collecting electrodes (2) and spraying electrodes (1) arranged adjacent and parallel to the collecting electrodes (2) and a cleaning device for spraying a cleaning liquid onto the collecting and spraying electrodes (2, 1).