Ozone generation assembly

Abstract

Ozone generation assembly with at least one electrically insulating dielectric support (1), wherein the back (1a) and the front (1b) of the insulating dielectric support (1) are provided with electrically conductive structures (2, 3), and wherein the electrically conductive structures (2, 3) are each coated with at least one insulating layer (4, 5), wherein the electrically conductive structure (2) on the back side (1a) of the insulating dielectric support (1) comprises at least two planar electrodes (2a, 2b), and wherein the electrically conductive structure (3) on the front side (1b) of the insulating dielectric support (1) comprises at least two electrically interconnected electrode structures (3a, 3b) which electrode structures (3a, 3b) form electrical capacitors with the at least two planar electrodes (2a, 2b) arranged on the back side (1a) of the insulating dielectric support (1), and wherein the electrode structures (3a, 3b) are formed from geometric elements having edges and geometric surfaces, characterized by that the electrode structures (3a, 3b) arranged on the front face (1b) of the insulating dielectric support (1) are each configured as a grid, wherein linear structures form the grid, and wherein the ratio R between the edge length L of the linear structures and four times the value of the square root of the geometric area S of the linear structures is greater than 2, where the edge length L is a sum of the lengths of all edges of the outer boundary of the linear structures forming the respective electrode structure (3a, 3b).

Description

[0001] The invention relates to an assembly for generating ozone, wherein at least one electrically insulating, dielectric carrier is provided, wherein the back and front of the carrier are provided with electrically conductive structures, and wherein the electrically conductive structures are each coated with at least one insulating layer.

[0002] Ozone production by generating a plasma based on the principle of dielectric hindrance has been known for about 100 years. The so-called Siemens tube is often used. The aim of using industrially produced ozone is to destroy oxidizable air components and pathogenic germs by treating the air with oxygen ions and ozone (O3 and O1). In the Siemens tube, known since 1857, a high alternating voltage of, for example, 3 to 6 kV is applied to two electrodes, resulting in electrical discharge phenomena. In particular, molecular atmospheric oxygen (O2) is dissociated, and ions and ozone (O1, O3) are produced.

[0003] From patent application WO 98 / 26482 A1, a flat module constructed according to the same physical principle is known, in which an electrode is enclosed between two glass plates. A metal grid or mesh covers the outer glass surfaces accessible to the air and forms an outer electrode. The high alternating voltage is applied to the outer and an inner electrode, with the ground potential always on the outside or on the side that could be touched.

[0004] A disadvantage of this design, as well as the well-known Siemens tube, is its relatively large and expensive construction, because the outer and inner electrodes must be firmly and without gaps in contact with a glass dielectric. Industrial, cost-effective manufacturing of these modules is difficult or even impossible. Furthermore, the efficiency decreases when the surface of the glass and the structures between the outer wire meshes become contaminated.

[0005] The function of a dielectrically hindered electrical discharge can be explained as follows: Between the electrodes connected to a high alternating voltage (e.g., 5 kV, 30 kHz) is a dielectric, usually made of glass. The general function of the two dielectric barriers is to hinder and ultimately interrupt the movement of electrons to the electrode. The dielectric not only impedes the electrons' movement towards the anode but also causes them to accumulate, thereby creating an opposing field to the external field driving the electron current. This opposing field increases until the external field and the opposing field exactly cancel each other out. By adjusting the parameters, extremely fast and, above all, reliable discharge interruptions can be achieved, which are essential in dielectrically hindered discharges.They contribute significantly to preventing the discharge plasma from abruptly transitioning towards thermal equilibrium. The opposite is intended: the goal is to generate as many fast electrons as possible, which transfer their kinetic energy through inelastic collisions to the atomic states that most effectively contribute to the desired plasma and ozone generation, while keeping energy transfer through electron collisions in loss channels to a minimum. The resulting discharge pattern at power densities relevant to applications is characterized by the formation of individual discharges, known as filaments. These filaments occur briefly and in large numbers. They are typically distributed across the entire electrode surface and exhibit stochastic characteristics both locally and temporally.Physically, the phenomenon can be described as follows: With increasing external voltage, unpredictable conditions arise somewhere within the discharge region at certain times, leading to locally confined discharges. Due to the dielectric hindrance of the electrodes, these discharges extinguish shortly after their occurrence because of the local opposing fields (image charges). Further, subsequent individual discharges occur and extinguish according to the same principle. It is usually noticeable that the filaments located on the outer wire grids are relatively small: The dielectric is enclosed by the rear electrode and the outer electrode, which is designed as a wire grid. During discharge, the luminous filaments can be observed in the immediate vicinity of the wires that extend towards the dielectric. The length of the filaments is only a few tenths of a millimeter.

[0006] A further disadvantage of the traditional technique using wire meshes is that the wires must be arranged with a minimum distance (the mesh size) between them. If the meshes are too small, the charges impede each other, and moreover, ozone and oxygen ions cannot be freely transported into the surrounding air. Ideally, a structure would be created that would produce practically flat filaments, which would then be in direct contact with the surrounding air.

[0007] It would also be desirable for the alternating electric field to extend into space. This is because it is known that polar molecules in particular dissociate in a rapidly alternating electric field.

[0008] Flat assemblies based on the principle of dielectrically hindered discharge are known – for example, from German patent application DE 199 31 366 A1. In these assemblies, a flat ceramic substrate has a continuous electrically conductive coating on its backplane and narrow electrodes on its frontplane, which are covered by a glass cover. The function is based on the fact that high electric fields form at the edges of the platinum electrode, which is located directly on the substrate, during capacitive recharging. These fields excite electrons in the outer glass layer, which is doped with, for example, barium oxide. The individual charges observed externally are not discharges – as in a Siemens tube – between the backplane and the electrode on the frontplane, but rather excitation states originating from the electric field generated at the edges during recharging processes.

[0009] A disadvantage of all known flat ozone generators is that the electrodes on the front and back must each be individually connected. Connecting the electrodes on the front, the side where ozone is generated, has systematic drawbacks, such as the tendency of the solder joints to sinter under the influence of ozone, and the associated need for cable routing to the high-voltage power supply. Because the front surface is exposed to various environmental conditions, there is also a risk of short circuits or surface breakdowns.

[0010] Publications JP H08 - 217 411 A, EP 0 837 032 A1, US 5 407 639 A and JP H07 - 309 605 A show further examples of generic flat ozone generators.

[0011] The object of the invention is to propose an assembly for generating ozone which avoids the disadvantages of the prior art.

[0012] The problem is solved according to the invention by an assembly for generating ozone according to claim 1.

[0013] According to the invention, at least two planar electrodes are arranged on the back side of an electrically insulating dielectric carrier, and at least two electrically interconnected electrode structures are arranged on the front side of the electrically insulating dielectric carrier. The electrode structures are formed from geometric elements with the largest possible ratio between edge length and geometric area in the form of grids. The electrode structure consists of at least two geometric elements. A plurality of elements is also possible. The ozone is preferably generated from air, with the energy for generation being provided by applying an alternating voltage. According to the invention, this is thus a flat assembly or a flat device for generating ozone. The individual elements active for generating the ozone are planar electrodes or...Electrode structures that can withstand high voltages. According to the invention, they are each designed as a flat surface and have a grid-like structure. The opposing electrode structures or electrodes form capacitors, through which ozone is generated by applying the high voltage.

[0014] According to the invention, the electrode structures arranged on the front side are configured such that the ratio between the edge length of the linear structures and four times the square root of the geometric area of ​​the linear structures is substantially greater than 2, where the edge length L is the sum of the lengths of all edges of the outer boundary of the linear structures forming the respective electrode structure. In one embodiment, the electrodes arranged on the back side are congruent, i.e., configured with substantially the same geometry. S is the geometric area of ​​the linear structures, and according to the invention, the ratio R between the edge length L and four times the square root of the area S is defined as R = L / (4 * √S). This ratio is substantially greater than 2 (R ≥ 2).

[0015] According to the invention, the electrode structure arranged on the front of the insulating dielectric support comprises at least two electrically interconnected electrode structures which form electrical capacitors with the at least two planar electrodes arranged on the back of the insulating dielectric support.

[0016] One embodiment includes the fact that at least one of the at least two electrically connected electrode structures is essentially rectangular. According to the invention, the at least two structures are connected to each other. Furthermore, in one embodiment, both of the at least two structures are configured such that they are essentially rectangular. "Rectangular" here means that the area covering the structures is essentially rectangular.

[0017] One embodiment provides that at least one of the at least two planar electrodes arranged on the back of the insulating, dielectric carrier is essentially rectangular in shape.

[0018] One embodiment provides that at least one of the planar electrodes arranged on the back of the insulating, dielectric carrier is designed in such a way that a substantially open area is created inside the planar electrode.

[0019] One embodiment involves the electrically interconnected electrode structures arranged on the front side of the insulating dielectric support and the planar electrodes arranged on the back side of the insulating dielectric support, each forming an electrical capacitor, being designed to be essentially congruent. The corresponding structures or electrodes thus have a similar design, for example, by covering structurally similar areas on the support.

[0020] The invention is explained in more detail with reference to the following drawings. They show: Fig. 1: a Siemens tube according to the state of the art for the production of ozone, Fig. 2: a flat module according to the state of the art, Fig. 3: the basic structure according to the state of the art, Fig. 4: a structure of the flat assembly according to the invention, Fig. 5 and Fig. 6: Electrical equivalent circuit diagrams of the design of the Fig. 4, Fig. 7: an electrode structure of the flat assembly according to the invention, and Fig. 8: another geometry of the electrode structure according to the invention.

[0021] The Siemens tube, known since 1857, is, as in Fig. 1. Assembled: A tubular glass body 12 – preferably made of borosilicate or quartz glass – is lined internally with an often mesh-like electrode 13. The electrode 13, made of conductive material, lies close to the inner glass surface of the tube 12, ideally without an air gap. The outer shell of the tube 12 also forms a tightly fitting mesh made of, for example, Steel mesh, which forms the outer electrode 11. If a high alternating voltage of, for example, 3 to 6 kV is applied to the inner 13 and the outer electrode 11, electrical discharge phenomena occur. In this process, molecular atmospheric oxygen (O2) is dissociated, producing ions and ozone (O1, O3).

[0022] In the Fig. Figure 2 shows a flat module operating according to the same physical principle, in which an electrode is enclosed between two glass plates. A metal grid or mesh covers the outer glass surfaces accessible to the air and forms the outer electrode 11. The high alternating voltage is applied to the outer electrode 11 and the inner electrode 13, with the ground potential always being on the outside, or on the side that could be touched, according to the invention. A disadvantage of this design, as well as of the known Siemens tube, is the relatively large and expensive construction, because the outer electrode 11 and the inner electrode 13 must lie firmly and without gaps on the glass dielectric 12.

[0023] The function of a dielectrically hindered electrical discharge can be explained as follows: Between the electrodes 11, 13, which are connected to a high alternating voltage (e.g., 5 kV, 30 kHz), there is a dielectric 12, usually made of glass. The general function of the two dielectric barriers is to hinder and ultimately interrupt the movement of electrons to the electrodes 11, 13. The electrons are not only impeded in their movement towards the anode by the dielectric 12, but also accumulated, thereby creating an opposing field to the external field driving the electron current. This opposing field increases until the external field and the opposing field exactly cancel each other out. Extremely fast, and above all, reliable discharge interruptions can be achieved by adjusting the parameters. These are of essential importance in dielectrically hindered discharges.They contribute significantly to preventing the discharge plasma from abruptly transitioning towards thermal equilibrium. The opposite is intended: the goal is to generate as many fast electrons as possible, which transfer their kinetic energy through inelastic collisions to the atomic states that most effectively contribute to the desired plasma and ozone generation, while keeping energy transfer through electron collisions in loss channels to a minimum. The resulting appearance of the discharges at power densities relevant to applications is characterized by the formation of individual discharges, the so-called filaments. These filaments occur briefly and in large numbers. They are normally distributed across the entire electrode surface and exhibit a stochastic character both locally and temporally. Physically, the phenomenon can be described as follows: As the external voltage increases, unpredictable conditions arise somewhere within the discharge region at certain times, leading to localized discharges. Due to the dielectric hindrance of the electrodes, these discharges extinguish shortly after their occurrence because of the local opposing fields (image charges). Further, subsequent individual discharges occur and extinguish according to the same principle.

[0024] Looking at the filaments located on the outer wire mesh, it is noticeable that these are accordingly Fig. 2 are relatively small: The dielectric 12 is enclosed by the rear electrode - still considered here in connection with the Siemens tube as the inner electrode 13 - and the outer electrode 11, which is designed as a wire grid.

[0025] During discharge, the luminous filaments 14 can be observed in the immediate vicinity of the wires that extend towards the dielectric 12. The length of the filaments 14 is only a few tenths of a millimeter.

[0026] A further disadvantage of the traditional technique using wire meshes is that the wires must be arranged with a minimum distance (the mesh size) between them. If the meshes are too small, the charges impede each other, and moreover, ozone and oxygen ions cannot be freely transported into the surrounding air. Ideally, a structure would be created that would produce practically flat filaments, which would then be in direct contact with the surrounding air.

[0027] It would also be desirable for the alternating electric field to extend into space. This is because it is known that polar molecules in particular dissociate in a rapidly alternating electric field.

[0028] The basic structure of flat assemblies according to the state of the art is described in Fig. 3. The substrate 1, made of ceramic or a comparable dielectric material, carries an electrically conductive layer on its back side 1a as an electrode 2. This electrode 2 can be a homogeneous, thin cover layer or, to minimize electrical capacitance, a mesh-like electrode. On the front side 1b are linear, thin electrodes 3, which can be configured in various geometries. The electrodes 3 on the front side 1b are covered with a thin, electrically insulating layer 4, which is "contaminated" with materials that have a low work function. Glasses alloyed with metal oxides such as barium oxide have proven effective in this context. To prevent uncontrolled discharges, the back side 1a is covered with an insulating material 5. For example, pure glass with good insulating properties is suitable.The contacts 6 to the electrodes 2 and 3 serve to connect the electrodes 2 and 3 to a high voltage source 7 (e.g. 5 kV - peak-to-peak - alternating voltage).

[0029] The inventive principle is in Fig. As described in Figure 4: The rear electrode 2 does not consist of a continuous layer, but of two electrodes 2a and 2b, each of which forms an electrical capacitor with the electrode 3 on the front side 1b (see the equivalent electrical circuit diagram below). Fig. 5 and Fig. 6) According to the invention, two capacitors are thus connected in series.

[0030] The function is as follows: When a voltage is applied to the two rear electrodes 2a, 2b, a capacitive circuit is coupled via the electrode 3 on the front side 1b. As a result of the applied high alternating voltage (at least 4.5 kV peak-to-peak at 30 kHz with a ceramic plate thickness of 0.4 mm), high electric fields form at the edges of the front electrode 3. These electric fields are transferred to the metal oxides with low work function located in the insulating glass layer 4, causing them to become highly excited. The electric field at the edges is thus effectively amplified, resulting in a very high electric field acting on the air molecules on the air-side surface of the insulating glass layer 4. This leads to local discharges, which manifest as a brief cold plasma in which oxygen molecules (O2) dissociate.The oxygen atoms (O1) produced by the energetic processes present in the plasma recombine to form triatomic oxygen (O3 = ozone). To produce triatomic oxygen (O3) from diatomic oxygen (O2), the stable diatomic oxygen must be destroyed by an energy input so that the monatomic oxygen O1 can subsequently recombine to form O3.

[0031] This process requires an energy supply.

[0032] The production of one gram of pure ozone requires an energy equivalent of approximately 1.7 Wh. To avoid dielectric losses and to increase the efficiency of the arrangement according to the invention, care is taken to keep the electrical capacitance of the arrangement as small as possible.

[0033] This is achieved by making the linear electrodes on the upper surface as narrow as possible in order to generate the highest possible ratio between the electrode area and their edge length. The geometry of the electrodes is thus selected such that the ratio between edge length L and geometric area S of the linear structures forming the respective electrode structures 3a, 3b is as large as possible. In particular, the value defined above should therefore be... R=L4*S They should be as large as possible, or at least larger than or equal to two. In particular, the electrodes should have a rectangular shape.

[0034] A structure like the one in [reference to a specific example] is advantageous. Fig. As described in Figure 7, the structures of electrode 3 on the front side form a grid. To the right and left of the grid lines, discharge structures of a specific width—usually approximately ±1 mm—form. Both electrodes 3a and 3b on the front side 1b are rectangular. They are electrically connected by a bridge-like structure. On the back side 1a, the electrodes 2a and 2b are indicated by dashed lines. These are also rectangular and have at least the same area as the front electrodes 3a and 3b. The back electrodes 2a and 2b are designed with a larger area than the front electrodes 3a and 3b. In particular, the back electrodes 2a and 2b are compact, meaning they are not grid-like. For example, they are solid.

[0035] Therefore, the minimum spacing of the lines forming the grid, including a certain safety margin, is approximately 3 mm. Parallel to the intersecting lines of the grid, the desired plasma formation occurs on the surface of the cover layer.

[0036] With appropriate dimensioning (e.g., a ceramic plate as a support with a thickness of 0.4 mm, an alternating voltage greater than 4.5 kV peak-to-peak with a frequency of 30 kHz) in accordance with the teaching of this invention, a largely homogeneous and actively luminous plasma of individual electrical discharges forms on the surface of the assembly according to the invention, resulting in a maximization of the electrical discharge activity that dissociates air molecules.

[0037] In Fig. Figure 8 describes a geometry in which the electrical voltage present near the edge of the support module 1 is advantageously relatively low.

[0038] A capacitor is formed between an electrode 2a, which runs parallel to the outer edges of the module on the rear side of the support 1, and an electrode 3a, which runs parallel to the outer edges of the module on the front side of the support 1. The resulting capacitor thus encompasses the support 1 as its boundary. The rear side is electrically connected to the high-voltage source 7, but is also grounded. An electrical connection is established from the rotating electrode 3a to a grid-shaped working electrode 3b, which is framed by the rotating electrode, i.e., essentially in its center. The ratio between the areas of the two parts 3a and 3b of the upper electrode is maximized. Opposite the working electrode 3b, on the rear side, is a flat second electrode 2b, which is connected to the other pole of the high-voltage source 7.One capacitor is thus formed from the two essentially rectangular electrodes 3b, 2b on the front and back sides in the center of the support 1. The second capacitor consists of the electrodes 3a, 2a, arranged along the edge of the support 1 and having the rectangular recess in the center.

[0039] It is advantageous that there is no dangerous high voltage near the edges and that the ability to radiate electromagnetic interference is minimized by the choice of the geometry according to the invention, without affecting the function of the arrangement.

[0040] All variations share the inventive teaching disclosed here that the supply of electrical energy takes place only from one side of the assembly and that the at least two electrodes on the back of the assembly and the at least one grid-shaped electrode arrangement on the front act electrically like capacitors connected in series. Reference symbol list 1 carrier 1a Reverse side 1b Front 2 Rear electrode 2a Electrode 2b Electrode 3 Front-facing grid-shaped electrode 3a grid-shaped electrode 3b grid-shaped electrode 4 Insulation layer 5 Insulation compound 6 Contacting 7 Voltage source 11 Outer electrode 12 glass bodies 13 Inner electrode 14 filaments

Claims

[1] Ozone generation assembly, with at least one electrically insulating dielectric support (1), wherein the back (1a) and the front (1b) of the insulating dielectric support (1) are provided with electrically conductive structures (2, 3), and wherein the electrically conductive structures (2, 3) are each coated with at least one insulating layer (4, 5), wherein the electrically conductive structure (2) on the back side (1a) of the insulating dielectric support (1) comprises at least two planar electrodes (2a, 2b), and wherein the electrically conductive structure (3) on the front side (1b) of the insulating dielectric support (1) comprises at least two electrically interconnected electrode structures (3a, 3b) which electrode structures (3a, 3b) form electrical capacitors with the at least two planar electrodes (2a, 2b) arranged on the back side (1a) of the insulating dielectric support (1), and wherein the electrode structures (3a, 3b) are formed from geometric elements having edges and geometric surfaces, characterized by , that the electrode structures (3a, 3b) arranged on the front face (1b) of the insulating dielectric support (1) are each configured as a grid, wherein linear structures form the grid, and wherein the ratio R between the edge length L of the linear structures and four times the value of the square root of the geometric area S of the linear structures is greater than 2, where the edge length L is a sum of the lengths of all edges of the outer boundary of the linear structures forming the respective electrode structure (3a, 3b). [2] Assembly according to claim 1, characterized by , that the at least two planar electrodes (2a, 2b) arranged on the back (1a) of the insulating dielectric support (1), with which the at least two electrically connected electrode structures (3a, 3b) arranged on the front (1b) of the insulating dielectric support (1) form electrical capacitors, each have a shape with a completely closed surface, the surface of which is larger than the surface of a respective electrode structure (3a, 3b). [3] Assembly according to one of claims 1 or 2, characterized by , that at least one of the at least two electrically connected electrode structures (3a, 3b) is rectangular in shape. [4] Assembly according to any one of claims 1 to 3, characterized by , that at least one of the at least two planar electrodes (2a, 2b) arranged on the back (1a) of the insulating dielectric support (1) is rectangular in shape. [5] Assembly according to claim 1, characterized by , that at least one of the at least two planar electrodes (2a, 2b) arranged on the back side (1a) of the insulating dielectric carrier (1) is designed in such a way that an open area is created inside the planar electrodes (2a, 2b). [6] Assembly according to claim 1, characterized by , that the electrically interconnected electrode structures (3a, 3b) arranged on the front (1b) of the insulating dielectric support (1) and the planar electrodes (2a, 2b) arranged on the back (1a) of the insulating dielectric support (1), which together form an electrical capacitor, are designed such that they are congruent.

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