JP2002346334A - Gas cleaning apparatus by plasma - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas cleaning apparatus by plasma which exhibits good treatment performance by radiating a streamer discharge stably to a functional material. SOLUTION: A conductive treatment member (23) on which a catalyst and an adsorbent are supported is arranged in the vicinity of the downstream side of a discharge electrode (21) which radiates a streamer discharge. A conductive frame member (30) is formed around the treatment member (23). An earthing terminal (31) is attached to the frame member (30). The treatment member (23) is earthed through the frame member (30).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma type gas purifying apparatus for deodorizing or harming odorous or harmful components in a gas by using plasma discharge.

[0002]

2. Description of the Related Art Conventionally, Japanese Patent Laid-Open No. 2000-140562 has been disclosed.
As disclosed in Japanese Patent Application Laid-Open Publication No. H10-107, there is known an apparatus that generates low-temperature plasma by electric discharge and promotes decomposition or adsorption of odorous or harmful components in gas using the low-temperature plasma. Cold plasmas are created by the excitation of air molecules, resulting in the production of fast electrons and slow positive ions. The energy of the fast electrons is very high, and energy exceeding 10 eV can be obtained by the fast electrons. On the other hand, positive ions are slow,
The thermodynamic temperature has the characteristic that it hardly increases.

[0003] Decomposition of odor components or harmful components by low-temperature plasma is caused by decomposition of odor gas molecules or harmful gas molecules by the collision of high-speed electrons and active species having high reactivity (hydroxyl radical (OH), ozone (O ₃ ), The reaction is performed by a chemical reaction caused by excited oxygen molecules (O ₂ ^* ). By using the low-temperature plasma in this manner, the apparatus can be configured at a lower cost than a so-called decomposition type gas processing apparatus using a combustion catalyst or chemical absorption.

As such a plasma type gas processing apparatus, an apparatus using a packed bed, a creeping discharge, a silent discharge, or a streamer discharge has been proposed. However, in an apparatus using a packed bed, a creeping discharge, and a silent discharge, it is necessary to cover an electrode disposed in a gas flow passage with an insulating material. Therefore, there is a problem that the gap of the gas flow passage is reduced by the amount of the insulating material, and the pressure loss of the gas flow is increased. In addition, if conductive dirt adheres to the insulating material, the performance tends to deteriorate.

On the other hand, in a device using streamer discharge, it is only necessary to provide two bare electrodes in the gas flow passage, and the two electrodes can excite the entire internal space of the gas flow passage. . Therefore, the pressure loss in the gas flow is small, and the performance is not easily degraded due to insulation deterioration. An apparatus using such a streamer discharge is disclosed in, for example, JP-A-8-323134 and JP-A-11-
No. 3,333,244.

On the other hand, in order to further improve the performance of a plasma type gas purifying apparatus, an apparatus combining a plasma discharge and a functional material has been proposed as disclosed in Japanese Patent Application Laid-Open No. Hei 8-266854. . According to the device,
Some of the odor gas components are electrochemically decomposed by the plasma discharge. On the other hand, the odorous gas components that have not been decomposed by the discharge are adsorbed and decomposed by a functional material that adsorbs and decomposes the gas components using at least one of ozone, heat, and ultraviolet light generated by the discharge.

[0007]

However, the above-mentioned device using a functional material has the above-mentioned problem because it does not use a streamer discharge. Further, in the above-described device, even if a streamer discharge is generated, it is difficult to stably maintain the streamer discharge. Therefore, it has been difficult to stably irradiate the functional material with streamer discharge.

[0008] The present invention has been made in view of the above points, and an object of the present invention is to provide a plasma-type gas purifying apparatus that exhibits excellent processing performance by stably irradiating a functional material with a streamer discharge. Is to provide.

[0009]

A plasma type gas purifying apparatus according to the present invention is provided in a flow path of a power supply and a gas to be processed, and is connected to the power supply and applied with a voltage from the power supply to provide a streamer. A discharge electrode for generating a discharge, a small hole containing a catalyst or an adsorbent and through which the gas to be treated is formed is formed, and arranged near the downstream side of the discharge electrode in the flow passage so as to irradiate the streamer discharge. And a processing member, wherein the processing member is grounded.

In the above-mentioned plasma type gas purifying apparatus, since the processing member is grounded, the processing member is stably irradiated with the streamer discharge. In addition, since the processing member is disposed near the downstream side of the discharge electrode and is separated only by a short distance enough to irradiate the streamer discharge, the radicals generated by the streamer discharge are short-lived in the air, though they are themselves short-lived. And enters the inside of the processing member before disappearing. As a result, the performance of the catalyst or the adsorbent of the processing member is improved. Further, high-speed electrons generated by the streamer discharge also enter the inside of the processing member, so that the performance of the processing member is further improved. As described above, the gas to be treated is purified by the streamer discharge,
It is also purified inside the processing member. Since the treatment is performed in two stages as described above, efficient purification is realized.

[0011] The plasma-type gas purifying apparatus may further include a ground terminal fixed to the processing member, wherein the processing member is formed of a conductive functional material, and a ground wire connected to the ground terminal. Is also good.

Further, in the plasma type gas purifying apparatus, the processing member is formed of a conductive functional material, and a frame member made of a conductive material surrounding the processing member, and a ground connected to the frame member. And a line.

As described above, since the processing member has conductivity, the processing member functions as a counter electrode, so that a discharge occurs between the discharge electrode and the surface of the processing member, and a streamer generated from the discharge electrode is formed. The discharge is easily irradiated to the processing member.

[0014] The plasma type gas purifying apparatus is characterized in that the processing member is formed of a conductive functional material, and is disposed so as to be in contact with a downstream portion of the processing member in a flow passage of the gas to be processed. And a ground line connected to the counter electrode.

[0015] This makes it easier for streamer discharge to occur and for the streamer discharge to be stably applied to the processing member.

It is preferable that the processing member has a predetermined electric resistance so that a minute arc is generated between particles of the functional material.

As a result, the functional material is more activated by the minute arc, and the performance of the catalyst or the adsorbent is improved. In addition, the performance of the catalyst or the adsorbent can be improved by heat generation due to electric resistance.

The plasma type gas purifying apparatus is characterized in that the processing member is formed of an insulating functional material, and is arranged so as to be in contact with an upstream portion of the processing member in a flow path of the gas to be processed. And a ground line connected to the counter electrode.

When the processing member has an insulating property,
Electric charges accumulate on the surface on the upstream side (that is, on the discharge electrode side) of the processing member, and the voltage difference between the discharge electrode and the processing member tends to be small, so that streamer discharge hardly occurs.
However, as described above, by disposing the grounded counter electrode on the upstream side of the processing member, the electric charge on the surface side of the processing member is discharged into the ground through the counter electrode. Therefore, a voltage difference between the discharge electrode and the processing member is secured, and the processing member is stably irradiated with the streamer discharge.

It is preferable that the counter electrode is formed in a net shape or a grid shape.

[0021]

As described above, according to the present invention, the discharge electrode is provided near the downstream side of the processing member made of the functional material, and the processing member is directly or indirectly grounded, so that the streamer discharge is generated. Irradiation was performed stably. Therefore, radicals and high-speed electrons generated by the streamer discharge can be injected into the processing member, and the performance of the processing member can be improved. Therefore, a synergistic effect of the purifying action by the streamer discharge and the purifying action of the processing member promoted by the streamer discharge can improve the gas purifying performance.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

<Embodiment 1> A plasma type gas processing apparatus according to this embodiment is an air purifying apparatus (1) for purifying air by oxidizing and decomposing odorous or harmful components contained in air to be treated. FIG. 1 shows a schematic configuration of the air purification device (1).

As shown in the figure, the air purification device (1) has a configuration in which each functional component is housed in a casing (10). As the functional components, a dust collecting filter (11) and a centrifugal fan (12) are provided. ) And the plasma reactor (20)
0).

An air inlet (15) for sucking air into the casing (10) is formed on one side surface (the right side surface in the figure) of the casing (10), and a purified air is blown out on the upper surface. Air outlet (16) is formed. The air inlet (15) is provided with a suction grill (15a), and the air outlet (16) is provided with a blow grill (16a). The air inlet (15) has a suction grill (15a).
The dust collecting filter (11) is arranged inside the inside, so that dust contained in the intake air is collected.

The air outlet (16) is formed on the upper surface of the casing (10) at the edge opposite to the air inlet (15) (the left edge in FIG. 1). The centrifugal fan (12) is provided in the casing (10) corresponding to the air outlet (16). This centrifugal fan (1
2), a fan power supply (12a) is connected. In the above configuration, the space between the air suction port (15) and the air outlet (16) in the inside of the casing (10) is a flow space (flow path of the gas to be processed) of the air to be processed. Then, when the centrifugal fan (12) is started, air to be processed is sucked into the casing (10) through the suction grill (15a) of the air suction port (15) and the dust collection filter (11). After the air to be treated is processed in the reactor (20) described in detail below, the air is blown from the outlet grill (16a) of the air outlet (16) to the casing (10).
It is blown out of.

FIG. 2 is an enlarged sectional view showing a main part of the plasma reactor (20), and FIG. 3 is a perspective view. The plasma reactor (20) includes a discharge electrode (21) as discharge means for generating low-temperature plasma, and a processing member (23) disposed downstream of the discharge electrode (21). The treatment member (23) is located in the discharge field (D) so that the discharge electrodes (2
It is located near 1).

As shown in FIG. 3, the processing member (23)
Has a number of small holes (23
It consists of a honeycomb-shaped conductive substrate (23a) on which b) is formed, and the substrate (23a) carries a catalyst and an adsorbent. The base material (23a) is provided with a conductive frame member (30) surrounding the base material (23a).

As the catalytic substance supported on the substrate (23a), for example, Pt, Pd, Ni, Ir, Rh, Co, O
s, Ru, Fe, Re, Tc, Mn, Au, Ag, C
A catalyst substance containing at least one of u, W, Mo, and Cr can be suitably used. These catalytic substances promote a chemical reaction when treating the air to be treated. The adsorbent adsorbs components to be treated such as odorous substances and harmful substances contained in the air to be treated,
For example, activated carbon or zeolite is used. As the adsorbent, porous ceramics, activated carbon fiber, mordenite, ferrierite, silicalite, or the like may be used, and at least one of them may be used.
Thus, the base material (23a) is a functional material that decomposes odorous and harmful components in the air.

The discharge electrode (21) is composed of an electrode plate (21b) and a plurality of needle electrodes (21c) fixed substantially orthogonal to the electrode plate (21b). Electrode plate (21b)
Is made of a mesh material, punched metal, or the like, and has a number of openings (21d) through which air passes in a direction perpendicular to the plane.

The discharge electrode (21) is arranged such that the electrode plate (21b) is substantially parallel to the surface of the substrate (23a) and the needle electrode (21c) is substantially perpendicular to the surface of the substrate (23a). Have been. As shown in FIG. 4 which is an enlarged view of the needle electrode (21c), the tip (21a) is formed as a point, and the point angle (θ) is formed at 60 °. In addition, the tip of the discharge electrode (21) is formed into a spherical shape with small roundness by rounding. The point angle (θ) may be 30 ° to 90 °.

An earth terminal (31) is provided on the frame member (30), and an earth wire (32) is connected to the earth terminal (31). That is, the frame member (30) is grounded.
Further, since both the frame member (30) and the base material (23a) have conductivity, the base material (23a) is also made of the frame member (3
0) is grounded. Note that the ground terminal (31) of the frame member (30) is not always necessary, and the ground wire (32) may be directly fixed to an arbitrary position of the frame member (30).

The positive electrode of a DC, AC or pulse high voltage power supply (24) is connected to the discharge electrode (21).
Is connected to the negative electrode of the high-voltage power supply (24), and the discharge electrode (21)
Streamer discharge is generated between the substrate and the substrate (23a). The discharge field (D)
Generates a low-temperature plasma. The low-temperature plasma includes, as active species, electrons, ions, ozone, and other radicals (hydroxy radicals, excited oxygen molecules, excited nitrogen molecules,
Excited water molecules).

In FIG. 1, reference numeral (13) denotes an ozone decomposition catalyst for decomposing ozone generated by electric discharge.

-Operation- Next, the operation of the air purification device (1) will be described.

When the operation of the air purification device (1) is started and the centrifugal fan (12) is started, first, the air suction port (15)
The air to be treated is sucked from the air, and the dust contained in the air is collected by the dust collecting filter (11). During operation of the device (1), the discharge electrodes (2
Streamer discharge is generated from 1), and the dust collection filter (1
The air from which dust has been removed in 1) passes through a discharge field (D) between the discharge electrode (21) and the processing member (23).

Here, the streamer discharge is caused by the discharge electrodes (2
The micro arc continues from the tip of 1) to the processing member (23) to form a plasma column with light emission. This micro arc is formed by the discharge electrode (21) and the processing member (23). And develops continuously at a narrow interval between equipotential surfaces. In the present embodiment, the point angle (θ) of the needle electrode (21c) of the discharge electrode (21) is set to 60 °.
Alternatively, since the angle is specified to be 30 ° to 90 ° and the tip is finely rounded, the minute arc easily spreads over a wide range. For this reason, in the plasma reactor (20) of the present embodiment, the streamer discharge (S) is generated in a wider range than in the related art as shown in FIG. 5 (the conventional streamer discharge (S ′) is represented by a virtual line). Shown).

In this embodiment, since the processing member (23) is disposed near the discharge electrode (21), the processing member (23)
Is irradiated by the streamer discharge generated from the discharge electrode (21).

When the air to be treated passes through the discharge field (D), it is turned into plasma by the action of the streamer discharge and becomes low-temperature plasma. The various active species generated by the discharge enter the processing member (23), and are excited to a higher degree by contacting with the catalyst to increase the activity, thereby efficiently removing harmful substances and odor components. React to decompose and remove these substances. Further, the high-speed electrons generated by the low-temperature plasma enter the inside of the processing member (23), so that the catalytic function is enhanced. Therefore, harmful substances and odorous substances in the air are quickly decomposed by a synergistic effect of the plasma and the catalyst.

Further, since the treatment member (23) also contains an adsorbent, harmful substances and odorous substances in the air to be treated are adsorbed by the adsorbent, and active species of low-temperature plasma act on these components. To accelerate the decomposition process. That is, more stable processing is performed by including the catalyst and the adsorbent in one processing member (23).

According to the present embodiment, the processing member (23) is replaced with the discharge electrode (21).
, And grounded, so that the processing member (23) can be stably irradiated with the streamer discharge generated from the discharge electrode (21). Therefore, short-lived radicals can enter the processing member (23) before being extinguished, and the performance of the catalyst and the adsorbent can be improved. Further, high-speed molecules can be injected into the processing member (23), and the performance of the catalyst and the adsorbent can be further improved. Thus, the air can be sufficiently purified by the synergistic effect of the plasma and the functional material.

-Modification- As shown in FIG. 6, the conductive frame member (30) is omitted, and the ground terminal (31) is directly fixed to a part of the conductive processing member (23). Is also good. In FIG. 6, the ground terminal (3
Although 1) is provided on the side surface of the processing member (23), the ground terminal (31) may be provided on the upper surface or the lower surface of the processing member (23), or may be provided on the front or back corner. .

<Embodiment 2> Embodiment 2 is based on Embodiment 1.
In the above, the configuration of the plasma reactor (20) is modified. The same parts as those of the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 7, in the second embodiment, the processing member (23) is made of a conductive base material (23a), and the counter electrode (22) is provided downstream of the base material (23a). Things. In FIG. 7, the discharge electrode (21) is illustrated as one needle electrode for simplicity of description.

As the counter electrode (22), an electrode plate having a large number of openings (22a) through which air passes in a direction perpendicular to the plane, such as a mesh material or a punched metal, is used.
The positive electrode of the high-voltage power supply (24) is connected to the discharge electrode (21), and the negative electrode of the high-voltage power supply (24) is connected to the counter electrode (22). Further, a ground wire (32) is connected to the counter electrode (22). The counter electrode (22) is in contact with the back side of the processing member (23), and therefore, the processing member (23) is grounded via the counter electrode (22) and the ground wire (32).

Also in this embodiment, the processing member (23) is stably irradiated with the streamer discharge generated from the discharge electrode (21), and the air is sufficiently purified by the synergistic effect of the plasma and the functional material. Will be.

-Modifications- In the above embodiment, the processing member (23) may be formed of a functional material having electrical resistance so that the processing member (23) has a potential gradient. For example, the potential difference between the discharge electrode (21) and the processing member (23) is 20 k.
V, the potential difference inside the processing member (23) may be 5 kV. The electric resistance of the processing member (23) is 10 ⁸ to 1
The value may be about 0 ¹⁰ Ω / cm. Since the processing member (23) has a predetermined electric resistance in this manner, a minute arc is easily generated between particles of the functional material forming the processing member (23), and the processing member (23) is generated by the minute arc. The further improvement of the performance of the catalyst and the adsorbent is achieved.

<Embodiment 3> Embodiment 3 is also equivalent to Embodiment 1.
In the above, the configuration of the plasma reactor (20) is modified. The same parts as those of the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 8, in the third embodiment, the processing member is formed of an insulating base material, and the counter electrode (22) is provided on the upstream side of the processing member (33). The processing member (33) carries the same catalyst and adsorbent as in the first embodiment. In FIG. 8, for the sake of simplicity, the discharge electrode (21) is illustrated as a single needle electrode.

Also in this embodiment, an electrode plate having a large number of openings (22a) through which air passes in a direction perpendicular to the plane, such as a mesh material or a punched metal, is used for the counter electrode (22). The high-voltage power supply (2
The positive electrode side of 4) is connected, and the negative electrode side of the high voltage power supply (24) is connected to the counter electrode (22). Further, a ground wire (32) is connected to the counter electrode (22). The counter electrode (22) is in contact with the surface side of the processing member (33),
The processing member (33) is grounded via the counter electrode (22).

From the discharge electrode (21), the insulating treatment member (3
When the streamer discharge is to be applied to 3), the counter electrode (22) may be provided on the back side of the processing member (33) as in the second embodiment. However, when the counter electrode (22) is provided on the back surface side of the processing member (33), the processing member (33) is insulative, so that a positive charge is applied to the surface of the processing member (33) which becomes the irradiation surface of the streamer discharge. This builds up, leaving no place for this charge to escape. As a result, the potential difference between the discharge electrode (21) and the processing member (33) becomes small, and it becomes difficult to stably irradiate the streamer discharge.

However, in this embodiment, the counter electrode (22)
Is provided on the surface side of the processing member (33), and the counter electrode (2
Since 2) is in contact with the surface of the processing member (33), positive charges on the surface side of the processing member (33) are discharged into the ground through the counter electrode (22). Therefore, it is possible to stably irradiate the streamer discharge even though the processing member (33) has an insulating property.

Therefore, also in the present embodiment, the streamer discharge generated from the discharge electrode (21) is treated by the processing member (3).
Irradiation can be stably performed on 3), and the air can be sufficiently purified by the synergistic effect of the plasma and the catalyst and the adsorbent of the processing member (33).

[Brief description of the drawings]

FIG. 1 is a structural diagram of an air purification device according to a first embodiment.

FIG. 2 is a cross-sectional view schematically illustrating a configuration of a main part of the plasma reactor according to the first embodiment.

FIG. 3 is a perspective view schematically showing a configuration of a plasma reactor according to Embodiment 1.

FIG. 4 is a partially enlarged view of a needle electrode.

FIG. 5 is a discharge state diagram of a streamer discharge.

FIG. 6 is a diagram corresponding to FIG. 3 according to a modification of the first embodiment.

FIG. 7 is a cross-sectional view schematically showing a configuration of a plasma reactor according to Embodiment 2.

FIG. 8 is a cross-sectional view schematically illustrating a configuration of a plasma reactor according to Embodiment 3.

[Explanation of symbols]

 (1) Air purification device (11) Dust collection filter (12) Centrifugal fan (15) Air inlet (16) Air outlet (20) Plasma reactor (21) Discharge electrode (22) Counter electrode (23,33) Processing material (23a) Base material (functional material) (24) High voltage power supply (power supply) (30) Frame member (31) Ground terminal (ground terminal) (32) Ground wire (ground wire)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B01D 53/38 B01D 53/36 B 53/86 53/34 116Z B01J 19/08 ZAB (72) Inventor Kagawa Kenyoshi 1304 Kanaokacho, Sakai-shi, Osaka Daikin Industries, Ltd.Sakai Seisakusho Kanaoka Factory F-term (reference) 4C080 AA07 BB02 CC01 HH05 JJ03 KK02 LL02 MM02 MM04 MM05 MM07 QQ01 QQ11 4D002 AB02 BA04 BA07 BA14 CA11 DA41 DA45 EA02 A21 A21A4A AB03 BA25X BA26X BA27X BA28X BA30X BA31X BA32X BA33X BA34X BA35X BA36X BA37X BA38X BB03 CC40 CD05 CD08 CD10 EA03 EA07 4G075 AA03 AA37 BA05 BD14 CA15 CA47 DA01 EA02 EB21 EC21 EE01 FC02 FB01 FB01 FB02

Claims (7)

[Claims] 1. A power supply (24), a discharge electrode provided in a flow path of a gas to be processed, connected to the power supply (24), and configured to generate a streamer discharge when a voltage is applied from the power supply (24). (21), a small hole (23b) containing a catalyst or an adsorbent and through which a gas to be treated flows is formed, and near the downstream side of the discharge electrode (21) in the flow passage so that the streamer discharge is irradiated. And a processing member (23, 33) arranged in the plasma gas purifier, wherein the processing member (23, 33) is grounded. 2. The plasma type gas purifying apparatus according to claim 1, wherein the processing member (23) is formed of a conductive functional material, and is fixed to the processing member (23). ) And a ground wire (32) connected to the ground terminal (31). 3. The plasma type gas purifying apparatus according to claim 1, wherein the processing member (23) is formed of a conductive functional material, and is formed of a conductive material surrounding the processing member (23). A plasma type gas purifying apparatus, further comprising a frame member (30), and a ground wire (32) connected to the frame member (30). 4. The plasma type gas purifying apparatus according to claim 1, wherein the processing member (23) is formed of a conductive functional material, and the processing member (23) is formed in a flow path of a gas to be processed. A counter electrode (22) arranged to contact the downstream portion;
And a ground wire (32) connected to the counter electrode (22). 5. The plasma-type gas purifying apparatus according to claim 4, wherein the processing member has a predetermined electric resistance such that a minute arc is generated between particles of the functional material. A plasma gas purifier characterized by the above-mentioned. 6. The plasma-type gas purifying apparatus according to claim 1, wherein the processing member (33) is formed of an insulating functional material, and the processing member (33) is formed in a flow path of a gas to be processed. A counter electrode (22) arranged to contact the upstream portion;
And a ground wire (32) connected to the counter electrode (22). 7. The plasma-type gas purifying apparatus according to claim 4, wherein the counter electrode (22) is formed in a mesh or grid.