JPH11333285A - Discharge gas treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To promote the disappearance of a residual charge between discharges in a gas treatment container and, at the same time, moderate the extreme unbalance of denseness and rareness in a gas treatment to increase the gas treatment efficiency. SOLUTION: This discharge gas treatment device comprises a plurality of disc-like baffles 22 of an insulator attached on a center electrode 6 in a gas treatment container 2 in such a manner that the baffles 22 are spaced L from each other as specified in a direction along the axis of the gas treatment container 2. Each of the baffles 22 changes the flow of a gas 10 between an outer electrode 4 and the center electrode 6 of the gas treatment container 2 to generate a flow component in the gas 10 in the radial direction of the gas treatment container 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used, for example, as an ozone generator, a NOx / SOx processor, a dioxin processor, a deodorizer, and the like. The gas to be treated is subjected to pulse streamer discharge (pulse generation). (Eg, ozone generation, NOx / SOx reduction, dioxin reduction,
Degassing etc.) Regarding the discharge gas processing device, more specifically, while promoting the disappearance of the residual charge between the discharge in the gas processor, and alleviating the density of the gas processing,
The present invention relates to means for improving gas processing efficiency.

[0002]

2. Description of the Related Art FIG. 7 shows a conventional example of this type of discharge gas processing apparatus. The discharge gas processing apparatus includes a gas processing device 2 having a cylindrical (for example, cylindrical) external electrode 4 and a linear (wire-shaped) central electrode 6 arranged on a substantially central axis thereof. and a pulse power supply 14 to be applied repeatedly high pressure pulse voltage V _P between the external electrode 4 and the center electrode 6 of the. Normally, the external electrode 4 is grounded as in this example, and a positive pulse voltage _VP is applied to the center electrode 6.

The inner diameter of the external electrode 4 is, for example, 10 to 100 m.
m, and the outer diameter of the center electrode 6 is, for example, about 0.2 to 3 mm. The magnitude of the pulse voltage V _P is for example 10 to 200
kV or so, the rise time of the pulse voltage V _P is for example 2
It is about 0 to 500 ns. However, these are merely examples, and the structure of the gas processor 2 and the gas
It may differ from this depending on the processing conditions such as the flow rate.

A gas 10 to be treated is supplied from one end of the gas processor 2 between the electrodes 4 and 6 from, for example, a gas source 8 and the gas 10 is supplied in a direction along the axis of the electrodes 4 and 6 (ie, in the direction along the axis of the electrodes 4 and 6). The pulse voltage _VP is repeatedly applied between the electrodes 4 and 6 from the pulse power source 14 in the state of flowing in the longitudinal direction), and the center electrode 6 is directed toward the external electrode 4 in all directions.
In addition, the pulse streamer discharge 16 is repeatedly generated uniformly in the longitudinal direction of the electrodes 4 and 6. The gas 10 is excited by the pulse streamer discharge 16 and desired treatment is performed on the gas 10, for example, generation of ozone and NOx as described above.
・ Processes such as SOx reduction, dioxin reduction, and deodorization can be performed. The processed gas 12 is taken out from the other end of the gas processor 2.

The technology using the pulse streamer discharge is more effective than the conventional technology using the silent discharge and the creeping discharge.
Gas processing efficiency against electric power consumed by discharge is 2
It is known to be nearly twice as high, and is attracting attention as a highly efficient gas processing technology.

[0006]

However, the above-mentioned conventional discharge gas processing apparatus has the following problems.

That is, at the time of pulse streamer discharge in the gas processor 2, for example, when the center electrode 6 has a positive potential (ie, when the pulse voltage _VP has a positive polarity) as shown in this example, as shown in FIG. A positive streamer 17 (a streamer having a positive charge at the tip and a negative charge at the subsequent portion) 17 extends from the center electrode 6 toward the external electrode 4. Therefore,
After the end of the discharge, as shown in FIG. 9, a donut-shaped negative residual charge 20 is generated near the center electrode 6, and a positive residual charge 18 is generated so as to surround the negative residual charge 20.
This residual charge 18 to generate an electric field E ₂ in the direction opposite to the electric field E ₁ (see FIG. 8) by the pulse voltage V _P.

[0008] When such residual charges 18, 20 remaining until the next discharge, since the electric field E ₁ by the pulse voltage V _P for the next discharge is weakened, the pulse streamer discharge is unlikely to occur . Therefore, it is difficult to efficiently input energy between the electrodes 4 and 6, and the processing efficiency of the gas 10 is reduced.

Further, in the case of a low gas flow rate where the flow rate of the gas 10 flowing into the gas processor 2 is small and a high repetition discharge operation condition in which the pulse streamer discharge 16 is generated in the gas processor 2 in a short cycle, the residual The above effects due to the charges 18 and 20 are particularly large.

For example, when this discharge gas processing apparatus is used as an ozone generator, it is necessary to generate ozone at a high concentration of, for example, about 10 ⁵ ppm in the gas processing apparatus 2. (For example, the gas residence time in the gas processor 2 is about several seconds to several tens of seconds), and the operation conditions are high repetition discharge (for example, about 1 kHz or more).

However, the diffusion time of the residual charges 18 and 20 is considered to be several milliseconds to several tens of milliseconds. When the cycle of repeated discharge is about 100 Hz or more, the diffusion time of the residual charges 18 and 20 is affected by the above. . Moreover, as the number of repetitions of the pulse streamer discharge increases, the residual charge 1
8 and 20, the residual charges 18, 20
The above effect is further enhanced. Further, in the low gas flow rate operation as described above, the gas flow in the gas processor 2 is in a uniform laminar flow state, and no radial flow component is generated. Cannot be expected to spread. Therefore, the above-mentioned effects of the residual charges 18 and 20 are particularly large.

Of course, contrary to the above-described example, the same problem as described above due to residual charges also exists when a negative pulse voltage _VP is applied to the center electrode 6.

Further, since the pulse streamer discharge 16 is generated in all directions from the thin center electrode 6 to the cylindrical external electrode 4, a high-density discharge is naturally generated near the center electrode 6. On the other hand, the density of discharge decreases near the external electrode 4. Therefore, the gas 10 in the gas processor 2
And the gas 10 passing near the center electrode 6 is subjected to high-density processing, whereas the gas 10 passing near the external electrode 4 is not subjected to much processing, As a whole, the gas processing efficiency decreases.

In particular, in the treatment of harmful substances by electric discharge (for example, reduction of NOx / SOx, reduction of dioxins, deodorization, etc.), the gas 10 to be treated must be treated uniformly (uniformly). If there is a gas 10 that simply passes, there are many disadvantages in processing.

In order to reduce the influence of the residual charge, for example, the gas flow rate is increased, the number of discharge repetitions is reduced, and the length of the gas processor 2 is shortened (however, the gas processor 2 Although it is conceivable to shorten the gas residence time (need to increase the number), in each case, the number of discharges applied to the passing gas decreases, and the gas treatment effect (for example, in the case of an ozone generator, (Generated ozone concentration). In addition, it is not a solution for reducing the density of the gas treatment.

Accordingly, the present invention promotes the elimination of residual charges between discharges in a gas processor,
The main purpose is to reduce the density of gas processing and improve gas processing efficiency.

[0017]

According to the present invention, there is provided a discharge gas processing apparatus in which a gas flowing between an outer electrode and a center electrode of the gas processor has a radial flow component of the gas processor. It is characterized in that a plurality of insulating fluids are provided at intervals in a direction along the axis of the gas processor.

According to the above configuration, when the gas to be processed passes through the variable fluid, a radial flow component of the gas processor is generated, and the radial flow component causes the radial flow component to be generated immediately after the pulse streamer discharge. Positive and negative residual charges generated in and out of the direction are mixed with each other and neutralized, thereby facilitating the disappearance of the residual charges. This makes it possible to efficiently input energy between the electrodes of the gas processor even under the operating conditions of a low gas flow rate and a high repetitive discharge, thereby improving the gas processing efficiency.

Further, due to the radial flow component of the gas, the gas which has been subjected to a dense treatment when passing near the center electrode and the gas which has been subjected to a rough treatment when passing near the external electrode are mutually inside and outside. Since the gas is processed while being mixed at different positions, the gas can be uniformly processed, and the density of the gas processing is reduced. Therefore, for this reason,
The overall gas processing efficiency is improved.

[0020]

FIG. 1 is a diagram showing an example of a discharge gas processing apparatus according to the present invention. Illustration of the gas source is omitted. Parts that are the same as or correspond to those in the conventional example of FIG. 7 are denoted by the same reference numerals, and differences from the conventional example will be mainly described below.

In this embodiment, a plurality of plate-shaped (disc-shaped in this example) fluids 22 are applied to the center electrode 6 in the gas processor 2 as described above on the axis of the gas processor 2. They are attached at a constant distance L from each other in the direction along the direction (that is, the longitudinal direction).

Each of the variable fluids 22 is, in this example, a central electrode 6.
It is attached so as to be substantially orthogonal to. The outer diameter of each variable fluid 22 is smaller than the inner diameter of the external electrode 4, and a space for flowing the gas 10 exists between each variable fluid 22 and the external electrode 4. With such a structure, each variable fluid 2
2 is a gas 10 flowing between the external electrode 4 and the center electrode 6.
To generate a flow component in the gas 10 in the radial direction of the gas processor 2 (in other words, the external electrode 4). The flow of the gas 10 when passing through the variable fluid 22 is schematically shown in FIG.

Each of the variable fluids 22 includes a center electrode 6 and an external electrode 4.
In order not to lower the dielectric strength between them, they are formed of an insulating material such as fluororesin, vinyl chloride, and acrylic. Therefore, even if provided with variable fluid 22, difficulty in applying a pulse voltage V _P from the pulse power source 14 between the center electrode 6 and the external electrode 4 does not occur.

When such a variable fluid 22 is provided, when the gas 10 to be processed passes through the variable fluid 22, a radial flow component of the gas processor 2 is generated. Since the positive and negative residual charges 18 and 20 (see FIG. 9) generated inside and outside in the radial direction immediately after the pulse streamer discharge are mixed with each other and neutralized, it is possible to promote the disappearance of the residual charges. Accordingly, energy can be efficiently input between the electrodes 4 and 6 of the gas processor 2 even under a low gas flow rate and a high repetition discharge operation condition, and the gas processing efficiency is improved.

Further, due to the radial flow component of the gas 10, a gas subjected to a dense treatment when passing near the center electrode 6, and a gas subjected to a rough treatment when passing near the external electrode 4. Are processed while being mixed with each other by changing the inner and outer positions, so that the gas 10 can be uniformly processed, and the density of the gas processing is reduced. Therefore, also for this reason, the overall gas processing efficiency is improved.

By providing the variable fluid 22,
If the pressure loss of the gas 10 in the gas processor 2 becomes large and there is any trouble, the gas 10 supplied to the gas processor 2
The pressure should be increased accordingly.

The interval L between the variable fluids 22 is preferably set as follows. That is, according to the experimental results, the number of discharge shots at which the effect of accumulating the residual charge is remarkable is about 100 to 1000 shots, depending on gas conditions and the like. Therefore, it is preferable that the gas 10 pass through the variable fluid 22 before the number of shots is reached in order to promote the above-described residual charge disappearance. That is, the interval L between the variable fluids 22 is such that the number of discharge shots applied to the gas 10 while passing between the two variable fluids 22 is 100 to 100.
Since the number of shots may be set to 0 or less, it is preferable to set a value represented by the following equation. Here, V is a gas flow velocity in the gas processor 2, f is a discharge repetition cycle, and a is a proportional constant (100 to 1000 in this case).

[0028]

## EQU1 ## L ≦ a · V / f

The shape of each of the variable fluids 22 is not limited to the example shown in FIG. 1 as long as it changes the flow of the gas 10 to generate a radial flow component therein. Another example of the variable fluid 22 is shown in FIGS.

FIG. 2 shows an example in which an abacus bead-shaped variable fluid 22 is attached to the center electrode 6. Of course, this fluid 22
A space through which the gas 10 flows is provided between the external electrodes 4. If the variable fluid 22 is formed in such a shape, the gas 10
Can be reduced.

The variable fluid 22 does not have to be axially symmetric with respect to the center electrode 6 as in each of the above examples. For example, as shown in an example shown in FIG.
It may be rotatably attached to the camera. By doing so, the variable fluid 22 is rotated by the flow of the gas 10 and the gas 10
Increases the diffusion effect.

FIG. 4 shows an example in which an annular (in this example, annular) variable fluid 22 having a cross-sectional shape projecting inwardly into a mountain shape is mounted inside the external electrode 4. According to the variable fluid 22, the gas 10 in the vicinity of the external electrode 4 can be more reliably diffused to the vicinity of the center electrode 6, so that the effect of reducing the density of the gas treatment is further enhanced.

FIG. 5 shows an example in which a perforated plate-shaped (disk-shaped in this example) variable fluid 22 having a plurality of holes is provided so as to partially partition between the center electrode 6 and the external electrode 4. It is. The position and number of holes may be determined by analyzing a gas flow or the like. Since the variable fluid 22 can also diffuse the gas 10 near the external electrode 4 to the vicinity of the center electrode 6 more reliably, the effect of relaxing the density of the gas processing is further enhanced.

In order to increase the amount of the processing gas, a plurality of gas processors 2 having the above-described variable fluid 22 may be provided in parallel. FIG. 6 shows such an example. In this example, a plurality of gas processors 2 having a variable fluid 22 are arranged side by side in a container
It has a structure to flow 0. The container 24 is grounded,
The external electrode 4 of each gas processor 2 is electrically connected to the container 24 by a support plate 26. The center electrodes 6 of the gas processors 2 may be connected in parallel to each other as in this example and connected to the pulse power supply 14, or may be connected in series and connected to the pulse power supply 14. The variable fluid 22 may be any of the examples shown in FIGS.

The external electrode 4 of the gas processor 2 is
A cylindrical shape other than the cylindrical shape, for example, a square cylindrical shape may be used. A tubular shape can be rephrased as a tubular shape.

[0036]

As described above, according to the present invention, the gas to be treated can generate a flow component in the radial direction of the gas processor by the variable fluid provided in the gas processor.
Due to the radial flow component, the positive and negative residual charges generated in and out of the radial direction immediately after the pulse streamer discharge are mixed with each other and neutralized, so that the disappearance of the residual charges can be promoted. This makes it possible to efficiently input energy between the electrodes of the gas processor,
Gas processing efficiency is improved.

Further, due to the radial flow component of the gas, the gas which has been subjected to a dense treatment when passing near the center electrode and the gas which has been subjected to a coarse treatment when passing near the external electrode are mutually inward and outward. Since the gas is processed while being mixed at different positions, the gas can be uniformly processed, and the density of the gas processing is reduced. Therefore, for this reason,
The overall gas processing efficiency is improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a discharge gas processing apparatus according to the present invention.

FIG. 2 is a diagram showing another example of a variable fluid together with a schematic diagram of a gas flow.

FIG. 3 is a diagram showing another example of a variable fluid together with a schematic diagram of a gas flow.

FIG. 4 is a diagram showing another example of a variable fluid together with a schematic diagram of a gas flow.

FIG. 5 is a diagram showing another example of a variable fluid together with a schematic diagram of a gas flow.

FIG. 6 is a view showing another example of the discharge gas processing apparatus according to the present invention.

FIG. 7 is a diagram showing an example of a conventional discharge gas processing device.

FIG. 8 is a diagram schematically showing a state during a pulse streamer discharge in a gas processor.

FIG. 9 is a diagram schematically showing the state of residual charges immediately after the discharge of the pulse streamer discharge in the gas processor.

[Explanation of symbols]

 2 Gas processor 4 External electrode 6 Center electrode 10 Gas to be processed 14 Pulse power supply 22 Variable fluid

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shigeru Kato 47 Nisshin Electric Co., Ltd., Umezu Takaunecho, Kyoto City, Kyoto Prefecture

Claims (1)

[Claims] 1. A gas processing device having a linear center electrode substantially on the center axis of a cylindrical external electrode, through which a gas to be processed flows between the two electrodes and in a direction along the axes of the two electrodes. A pulse power supply that repeatedly applies a pulse voltage between an outer electrode and a center electrode of the gas processor to repeatedly generate a pulse streamer discharge between the two electrodes. Inside, a variable fluid made of an insulator that causes a gas flowing between the outer electrode and the center electrode to generate a radial flow component of the gas processor is spaced apart from each other in a direction along the axis of the gas processor. A discharge gas treatment device comprising a plurality of discharge gas treatment devices.