RU154043U1 - OZONE GENERATOR USING A PULSED SLIDING DISCHARGE - Google Patents

Abstract

1. An ozone generator containing a discharge chamber in the form of a rectangular parallelepiped, inside which are laid flat electrodes of high and low voltage and a dielectric plate for an electric barrier, which is placed between the electrodes of high and low voltage, and there are inlet and outlet openings, as well as installed outside the discharge camera source of high voltage pulses connected to the electrodes, characterized in that the high voltage electrode is made in the form of a finned flat surface. 2. The ozone generator according to claim 1, characterized in that the ribs of the high voltage electrode are tightly laid on a dielectric plate, the other side of which is tightly adjacent to the low voltage electrode. Ozone generator according to claim 1 or 2, characterized in that the heat is removed from the electrodes through channels formed by the edges of the high voltage electrode and the dielectric plate. An ozone generator according to claim 1 or 2, characterized in that the ribs have a curved shape and there is a gap between the rows of ribs. 5. The ozone generator according to claim 1, characterized in that the high voltage electrode is made in the form of a finned surface, has a width of 32-120 mm and, accordingly, the number of rows of fins from 4 to 16.6. The ozone generator according to claim 1 or 2, or 5, characterized in that the discharge chamber is made in the form of a finned surface.

Description

The solution relates to devices for the production of ozone from oxygen or air and can be used to purify water, gas emissions, treatment of premises and in medicine.

One of the most important tasks facing modern society is to protect the environment. Its key component is the issue of water treatment and purification of various kinds of wastewater and gas emissions from toxic compounds.

Ozone technologies are becoming increasingly widespread for the successful solution of the task. Ozone is one of the most powerful oxidizing agents, which determines its attractiveness for use for various purposes, primarily for the disinfection of drinking water. Its extremely valuable property is its environmental friendliness - the ability to decompose to oxygen.

Ozone generators of various constructive designs are known (patents No. 2275324, No. 2258670, No. 2263068, No. 2261837, No. 2289542, No. 2301773, etc.). The numerous designs of ozone generators can be divided into three main groups.

1. Ozone generators of a coaxial design operating on a barrier discharge (the discharge zone is located between two ceramic surfaces).

A significant drawback of coaxial structures is the technological complexity of their manufacture and high cost. Coaxial discharge devices require the manufacture of tubes made of special quartz glass or ceramics calibrated both in diameter and in wall thickness. The application of ionizing electrodes to the inner surface of the tubes is a complex process. Moreover, the assembly of a coaxial ozone generator requires high accuracy of installation of both ionizing electrodes relative to each other, which necessitates high precision manufacturing, as well as other structural elements.

2. Ozone generators with a flat design of ionizing electrodes operating on a surface discharge (the discharge zone is located between the ceramic, dielectric and electrode).

These devices have significant operational disadvantages. They do not comply with one of the basic requirements for medical ozonizers - the absence of ionizing electrodes in the discharge zone. Protection of ionizing electrodes greatly complicates the design of discharge devices of this type and reduces the stability of their work. For ozone generators operating on a surface discharge, dehumidification of the air is required when it is supplied to the discharge zone. The presence of moisture in the air dramatically reduces the life of the ozone generator. For the operation of the ozone generator, it is necessary to have a sealed enclosure and an effective heat removal system, which leads to a significant complication and cost of the discharge device.

3. Discharge devices of ozone generators operating on a corona discharge (the discharge zone is located between two metal electrodes).

This category of discharge devices is characterized by the complexity of the structural implementation and the reduced lifetime, which is the result of erosion of the high-voltage electrode. Such devices require periodic replacement of a high voltage ionizing electrode.

A common significant drawback of the above constructions of ozone generators is the instability of operation, low maintainability, difficulty in scaling and high sensitivity to conditions of humidity, pollution and dustiness of the air.

The solution to the problems of improving ozone installations of any capacity depends on the development and implementation of new types of discharge chambers based on the use of more efficient types of discharge.

Recently, much attention has been paid to the sliding discharge, which has a number of unique properties that make it very promising for use in the practice of ozone synthesis.

A sliding surface discharge is characterized by special properties compared to other types of discharges, namely:

1) the development of a discharge in a thin surface layer of gas at the interface between solid and gaseous dielectrics;

2) significant power input into the gas, determined by high values of voltage and current in the discharge system;

3) the flat geometry of the development of the discharge, allowing you to organize a discharge on the walls of a rectangular channel;

4) a wide range of operating pressures and the possibility of initiation, both in pulsed and in frequency modes.

Discharges sliding over the surface of the dielectric are a well-distributed source of ultraviolet radiation due to high electric field strengths. With their help, energy can be supplied to the near-surface region of the gas flow.

The impact of a pulsed sliding surface discharge on the gas flow is almost instantaneous. High values of voltage and current provided effective excitation of vibrational and electronic degrees of freedom of molecules.

The thickness of the plasma layer in the air stream is about 0.4 mm, which is comparable with the thickness of the boundary layer on the channel wall. Thus, during the development of a sliding surface discharge, the main energy input occurs in the region of the boundary layer of the flow.

A characteristic feature of a sliding discharge is the effective excitation of the electronic levels of molecules, which, at high electric field strengths, consumes (along with ionization) a significant fraction of the energy absorbed in the discharge plasma.

An analysis of the dynamics of shock waves from the region of a sliding discharge shows that this type of discharge provides a high-energy effect on both the laminar and turbulent boundary layers. Based on a comparison of the experimental and calculated dynamics of the flow, it was found that the fraction of the discharge energy transforming into heat during the energy supply (~ 200 ns) increases from 15% to 65%

When a high-voltage voltage pulse with an amplitude of 10 ⁴ -10 ⁵ V and a slew rate of ~ 10 ¹² V / s in the discharge gap is exposed to the electrodes of the sliding discharge, the conditions typical for nanosecond electrical breakdown are formed. The electric field in the gap can be amplified up to 10 ² times on the microroughness of the fin surface of the electrodes and dielectric. The period of development of the discharge becomes comparable with the period of occurrence of elementary processes in the plasma, which leads to a deviation from the avalanche (Townsend) and approximate mechanisms.

The specificity of a sliding discharge is determined by the active interaction of the discharge plasma with the surface of the dielectric, which is reflected in the spectral characteristics of the plasma radiation. The sliding discharge channel is limited in space by the dielectric substrate, therefore, its cross-sectional area is smaller, and the linear electrical resistance is correspondingly greater than that of a free spark discharge. The small inductance and relatively high resistance of the completed sliding discharge provide a high power of energy release in the discharge channel, which leads to the formation of a dense high-temperature plasma with a large emitting surface area.

A device [1] is known, containing a package of rectangular high-voltage and low-voltage electrodes separated by rectangular dielectric plates, the electrodes designed to connect to zero potential made flat, and the electrodes designed to connect high voltage, made in the form of corrugated plates having edges on the ridges protrusions defining the gap between the electrode and the dielectric plate.

However, this ozone generator is not equipped with a heat sink system both from the side of high-voltage electrodes and low-voltage electrodes, since such a design does not allow this. The disadvantage is the connection method for connecting the high and low voltage electrodes to the power source, since a conductor is soldered to each electrode, which is soldered to the common bus with its other end. The disadvantage is the low concentration of ozone in the gas-ozone mixture due to the fact that the discharge occurs only on the ridges of the corrugated electrode and most of the gas flow remains unused.

Closer to the device is an ozonizer [2]. In an ozone generator containing a discharge chamber in the form of a rectangular parallelepiped, inside which a stack of flat rectangular metal electrodes and rectangular dielectric plates serving as electric barriers are stacked, the electrodes are stacked so that the odd plates are adjacent to one side of the chamber, and the even ones are adjacent to the other, and the sides themselves are common high and low voltage rails respectively. The opposite sides of the even and odd row electrodes from the common buses are separated by rectangular dielectrics, the thickness of which is equal to the thickness of the flat electrodes, and form tight contact with each other in order: a high voltage metal bus, plus a metal electrode, plus a dielectric, plus a low voltage metal bus. Rectangular dielectric plates are placed between the electrodes, touching their opposite edges with common metal busbars of high and low voltage, and the other two protrude behind the metal electrodes - the overlap for the breakdown voltage in the section of the high voltage electrode - dielectric - air discharge gap - dielectric - low voltage electrode. The lower and upper sides of the discharge chamber are made of dielectric material. The gas inlet and outlet are made on the front and rear sides of the chamber of dielectric material, in which there is a pipe in the center. An inlet cavity is located in the chamber between the front side with the nozzle and the inlets of the discharge gaps, and the outlet cavity is located between the outlet gaps and the back side with the nozzle, the volume of the outlet cavity being 2-3 times larger than the inlet. A metal screen is installed in the inlet cavity towards the gas flow, onto which a high negative potential can be supplied. The dielectric barrier consists of two plates with a thickness of 0.1-3 mm and separated by spacers to form an air gap with a gap of 0.5-2 mm, where a quiet electric discharge occurs. The sides of the dielectric plates that are adjacent to the electrodes are metallized (with a conductive layer, a metal film, graphite) so that an electric discharge does not occur between the electrode and the dielectric, forming contact with each other. In this case, the electrode and the conductive film on the dielectric will have the same electric potential.

A power source is connected to the high and low voltage buses and at the same time they are used to remove heat from the electrodes. To do this, ribbed radiators for air cooling or water-cooled radiators are attached to the common tires, which are the sides of the chamber, outside the discharge chamber. Heat is removed from the discharge gaps to the cooling radiators through electrodes with good thermal conductivity and optimal thickness.

The disadvantages of the known device include the following. The water cooling system is technologically very complex. In addition to planes and channels, each electrode has a water inlet and outlet fitting, recesses where dielectric plates are soldered, which requires safe sealing and the presence of high voltage decouples. The system of input and output channels by the number of electrodes for

gas flows not only complicates the design, but also contributes to a decrease in ozone concentration due to the passage and self-decomposition of ozone through these narrow channels. Loss of ozone occurs due to small cross sections of the inlet and outlet ducts (they are equal) of gas flows in relation to the volumes of the discharge gaps, which does not allow for high ozonizer performance.

The technical result of the claimed solution is the possibility of ozone synthesis using a sliding discharge, which increases the productivity and reliability of the ozone generator.

The specified technical result is achieved in that the ozone generator containing the discharge chamber in the form of a rectangular parallelepiped, inside which are laid flat electrodes of high and low voltage and a dielectric plate for the electric barrier, which is placed between the electrodes of high and low voltage, and there are inlet and outlet openings, as well as a source of high voltage pulses installed outside the discharge chamber, connected to the electrodes, characterized in that the high voltage electrode is flax in the form of a finned flat surface.

Preferably, the ribs of the high voltage electrode are tightly laid on a dielectric plate, the other side of which is snug against the low voltage electrode.

The heat removal from the electrodes is preferably carried out through channels formed by the ribs of the high voltage electrode and the dielectric plate. The ribs are preferably curved and there is a gap between the rows of ribs. The high voltage electrode is preferably made in the form of a finned flat surface, has a width of 32-120 mm and, accordingly, the number of rows of fins from 4 to 16.

The discharge chamber can be made in the form of a finned flat surface.

The discharge chamber, made in the form of a finned flat surface, allows the implementation of a block system for assembling the structure, which facilitates repair and maintenance at the operating site, and also allows you to quickly change the element base of other structural units to increase competitiveness.

Also, the fin surface of the electrodes increases the area of its thermal contact with the environment by hundreds or more times, thereby contributing to an increase in the heat transfer intensity and a drastic decrease in temperature.

Brief Description of the Drawings

In FIG. 1 shows an ozone generator perpendicular to the direction of the gas flow, and also in the lower part of the drawing is a section of the chamber of the ozone generator in the direction of the gas flow along the axis of symmetry, where 1 is a discharge chamber, 2 is a high-voltage electrode, 3 is a dielectric, 4 is a low-voltage electrode, 5, 6 - inlet and outlet openings with nozzles, 7 - discharge gap, 8 - sealing gaskets, 9 - source of high voltage pulses.

In FIG. Figure 2 shows a graph of the effectiveness of the cooling process of the structure, and as a result, thermal stabilization of the ozone generation process due to the flow of the ozone-air mixture through the formed multiple channels.

In FIG. 3 shows a practical example of a pulsed creeping discharge, where 14 is the glow of the discharge.

Implementation of a utility model.

In an ozone generator containing a discharge chamber in the form of a rectangular parallelepiped, inside which are laid flat electrodes and a dielectric plate for an electric barrier and there are inlet and outlet openings. According to the invention, the high voltage electrode is made in the form of a finned surface that is tightly in contact with the dielectric plate, and the other side of the dielectric plate is tightly in contact with the low voltage flat electrode. The discharge chamber formed by high and low voltage plates with a dielectric plate located between them is sealed. An oxygen-containing gas mixture enters the discharge chamber through the inlet, and flows through the numerous channels formed by the edges of the high voltage electrode and the dielectric plate. Ozone formed under the influence of a high-voltage pulse discharge is discharged from the discharge chamber through the outlet.

Comparative analysis with the prototype shows that the inventive device is characterized by the presence of elements, the design feature of which, namely, the implementation of the high-voltage electrode in the form of a flat plate with a large number of formed from the material of the plate profiled according to a certain law of the ribs, tightly adjacent to the dielectric plate, between which in the discharge an electric discharge occurs in the gap, which, in turn, contributes to the addition of new properties to the gas stream flowing along the animated channels.

Thus, the claimed device meets the criterion of "novelty" and the combination of technical features of ozone generation can be attributed to the "moving discharge".

Comparison of the claimed device with other technical solutions shows that the proposed device lacks a complex cooling system and current leads simplified the design of the ozone generator, reduced its size and weight. All elements of the ozone generator are assembled from easily accessible (in the manufacturing process) flat and rectangular parts, which increases reliability and service life. This allows us to conclude that the technological solution meets the criterion of "inventive step".

The removal of heat generated in the discharge chamber 1 (see Fig. 1) in the process of ozone generation is provided by the actual incoming gas mixture. According to research results, an increase in the heat transfer coefficient from the air flow is significantly affected by additional turbulence of the flow due to the destruction of the boundary layer. Structurally, this effect is achieved by the formation of discontinuities of the ribs along the way, giving the ribs a curved shape, as well as curving the input edge of the rib to create Taylor-Gertler microvortices. The heat sink efficiency is significantly affected by the geometrical parameters of the fins (the finning coefficient of such a surface reaches φ = 11) and the flow rate of the gas mixture. The flow rate of the gas mixture through the discharge chamber 1, and, consequently, the cooling efficiency is determined by the operation of the ejector or the performance of the compressor (fan).

The operation of the device is as follows.

Un-dried air is supplied through the nozzle 5 (see Fig. 1) into the discharge gap 7 formed between the high voltage electrode 2 and the dielectric plate 3. When voltage is applied from the high voltage pulse source 9 to the high voltage electrodes 2, an electric barrier discharge 14 occurs (see Fig. 3) and ozone is generated. Through the inlet 6, an oxygen-containing gas mixture enters the discharge chamber 1, which flows through the numerous channels formed by the ribs of the high voltage electrode 2 and the dielectric plate 3. The ozone formed under the influence of the high voltage pulse 14 is removed from the discharge chamber 1 through the outlet 7 under the action of differential pressure source (ejector or fan) to the consumer. An electric discharge occurs between the poles formed by the ribs of the high voltage electrode 2, which are in close contact with the dielectric plate 3, and the low voltage electrode 4, tightly pressed against the dielectric plate from the opposite side. Discharge 14 of this type is described in [3, 6, 7, 8] and is classified as a creeping discharge. The dielectric plates 3 are separated by sealing distance pads 8 to form an air gap with a gap, where a quiet electric discharge arises around the edge of the high voltage electrode and, at the corresponding voltage, an even glow forms, uniformly pressed to the surface. In addition, so-called “triple points” (electrode-gas-solid dielectric) are formed, the presence of which facilitates the initiation of a discharge. Obviously, the more ionized oxygen atoms, the more and faster the reactions of ozone formation from the gas stream. Due to the reaction and electric discharge between the barriers, the gas temperature rises. Therefore, the formed ozone must be quickly removed so that the reverse process of its formation does not occur. Thus, due to the simple design of the discharge chamber, the ozone self-decomposition sharply decreases inside and at the exit of the discharge gaps. The choice of material for the electrodes, when the discharge passes between the dielectric plates, is not critical. The thickness of these electrodes is selected so as to remove heat from the discharge gap.

Metals with good thermal conductivity are suitable here: aluminum and its alloys, stainless steel, etc.

By selecting the number of electrodes and the discharge area, you can change the performance of the ozone generator.

As dielectric plates (barriers), you can use ordinary glass with a permittivity ∈ = b-9, ceramics with ∈> 10 [4, 5]. The value of the dielectric constant e affects the electric field Ε (dimension V / m) near the dielectric plate, i.e. the electric field depends on the relation ^∈ / ∈ ₁ where: ∈ ₁ is the dielectric constant of the air, and ∈ is the dielectric constant of the plate (barrier). If the electric field between the electrodes is E ₀ = U / d, where U is the voltage at the electrodes (B), d is the gap between the electrodes (m), then for ∈> 10 the electric field in the air gap is E≈2E ₀ [4], those. the value of the dielectric constant affects the power consumption of the ozone generator.

Comparative tests of ozone generators of the claimed and coaxial designs confirmed the effectiveness of the ozone generator, in which an electrode made in the form of a finned surface is used as a high-voltage one. In FIG. Figure 2 shows the dependence of the heat transfer coefficient on the mass air flow rate, as can be seen on the graphs, where curve 10 is a multichannel tube with fins without offset, curves 11, 12, 13 reflect fins with an offset of 40, 51, 70 mm, respectively.

Table 1 shows experimental data comparing different types of discharge.

The coaxial type ozone generator high voltage electrode has a length of 200 mm and an inner diameter of 23 mm. Area - 14444 mm ² .

The high-voltage electrode of the ozone generator, made in the form of a finned surface, has a rectangular shape with a size of 70 × 300 mm. Area - 21000 mm ² . In the comparative tests (see the practical test example in Fig. 3), a single high-voltage pulse source with a power of 6.0 kW was used. The productivity of a coaxial type ozone generator is 1000 mgO ₃ / h. The output of ozone from a surface unit is 0.069 mgO ₃ / mm ² . Productivity of the ozone generator, the high-voltage electrode of which is made in the form of a fin surface - 2730 10

mgO ₃ / hour.

The output of ozone from a surface unit was 0.13 mgO ₃ / mm ² .

Conclusion: the specific productivity of the ozone generator, the high-voltage electrode of which is made in the form of a fin surface, is 1.89 times higher than the specific productivity of the coaxial type ozone generator.

Information sources

1. Patent, Russia 19. RU. (11) 94035978/26 (13) A1, MKI (51) 6 СВВ 13/11.

2. Patent, Russia 19. RU. (11) 2061651 (13) A1, MKI (51) 6 СВВ 13/11, prototype.

3. Yu.V. Filippov, V.A. Voblikova, V.I. Panteleev "Electrosynthesis of Ozone", Moscow University Press, 1987.

4. B.M. Tarasov "Physics of dielectric materials", M., Energoizdat, 1982.

5. I.S. Roz, Yu.M. Float, "Dielectrics", M., "Radio and Communications", 1989.

b. V.V. Lunin M.P. Popovich S.N. Tkachenko “Physical Chemistry of Ozone” M: Proceedings of Moscow State University 1998 448 s

7. Grigoriev A.N. Pavlenko A.V. Ilyin A. V. “Electric discharge on the surface of a solid dielectric. Part 1. Features of the development and existence of the surface discharge "Izvestia Tomsk Polytechnic University No. 1 volume 309/2006

8. Latfullin D.F. Abstract “Pulsed sliding surface discharge in the gas-dynamic flow of Moscow State University. 2009 year

Claims (6)

1. An ozone generator containing a discharge chamber in the form of a rectangular parallelepiped, inside which are laid flat electrodes of high and low voltage and a dielectric plate for an electric barrier, which is placed between the electrodes of high and low voltage, and there are inlet and outlet openings, as well as installed outside the discharge camera source of high voltage pulses connected to the electrodes, characterized in that the high voltage electrode is made in the form of a finned flat surface. 2. The ozone generator according to claim 1, characterized in that the ribs of the high voltage electrode are tightly laid on a dielectric plate, the other side of which is tightly adjacent to the low voltage electrode. 3. The ozone generator according to claim 1 or 2, characterized in that the heat is removed from the electrodes through channels formed by the edges of the high voltage electrode and the dielectric plate. 4. The ozone generator according to claim 1 or 2, characterized in that the ribs have a curved shape and there is a gap between the rows of ribs. 5. The ozone generator according to claim 1, characterized in that the high voltage electrode is made in the form of a finned surface, has a width of 32-120 mm and, accordingly, the number of rows of fins from 4 to 16. 6. The ozone generator according to claim 1 or 2, or 5, characterized in that the discharge chamber is made in the form of a finned flat surface.

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