JP7267800B2 - plasma reactor - Google Patents

Description

The present invention relates to plasma reactors.

A plasma reactor is conventionally known as a device for decomposing harmful components such as hydrocarbons (HC) contained in exhaust gas. Further, plasma reactors are required to have improved HC decomposition efficiency.

Therefore, it has been proposed to equip the plasma reactor with an HC adsorption catalyst containing an HC adsorbent such as zeolite and a catalytically active component such as a noble metal. Such HC adsorption catalysts are supported, for example, on the surfaces of insulating carriers arranged opposite each other in the plasma reactor. HC in the exhaust gas is adsorbed by the HC adsorbent and catalytically purified, and is also purified by plasma generated by discharge between insulating carriers (electrode panels) (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2005-90400

However, plasma reactors may require improved discharge performance.

For example, condensation of water vapor may occur due to, for example, a decrease in the internal temperature of the plasma reactor, and the resulting moisture may wet the hygroscopic HC adsorbent (adsorbent bed), increasing its conductivity. . When the conductivity of the HC adsorbent (adsorption layer) increases, it becomes difficult to transfer electrons between the insulating carriers (electrode panels). There is a problem that the HC decomposition performance by plasma is lowered.

INDUSTRIAL APPLICABILITY The present invention is a plasma reactor having excellent discharge performance between electrode panels and excellent HC decomposition performance.

The present invention [1] includes a casing having an inlet through which exhaust gas flows in and an outlet through which exhaust gas flows out; a plurality of electrode panels spaced apart from each other in a second direction perpendicular to each other, wherein the pair of electrode panels facing each other in the second direction are arranged such that at least one of the electrode panels is the electrode panel of the other side; is provided with an adsorption layer for adsorbing hydrocarbons, the adsorption layer having a predetermined pattern and containing a plasma reactor.

In the plasma reactor of the present invention, at least one of the electrode panels facing each other has an adsorption layer that adsorbs hydrocarbons on the surface facing the other electrode panel. The layers are formed as predetermined patterns. That is, an adsorption layer is pattern-formed on at least one side of the electrode panel, and a region where the adsorption layer is formed (adsorption region) and a region where the adsorption layer is not formed (exposed region) are divided into predetermined areas. Arranged as a pattern.

In such a plasma reactor, since the adsorption layer is patterned on the surface of the electrode panel, the edges of the adsorption layer are increased compared to the case where the adsorption layer is formed on the entire surface of the electrode panel. be able to. At the edges of the adsorption layer, electron transfer between the electrode panels is likely to occur. Therefore, by increasing the edge of the adsorption layer, the discharge between the electrode panels can be promoted.

Furthermore, in the above plasma reactor, the water absorption rate of the region where the adsorption layer is not formed (exposed region) is lower than the water absorption rate of the region where the adsorption layer is formed (adsorption region), and the drying efficiency is excellent. ing. Therefore, for example, even when condensation of water vapor occurs inside the plasma reactor, which causes wetting of the adsorption layer and deterioration of the discharge performance, the region where the adsorption layer is not formed (exposed region) should be kept dry. Therefore, deterioration of discharge performance can be suppressed.

As a result, the above plasma reactor can achieve excellent discharge performance and HC decomposition performance.

FIG. 1 is a schematic configuration diagram of a vehicle equipped with a first embodiment of the plasma reactor of the present invention. FIG. 2 is a perspective view showing the electrode panel of the first embodiment of the plasma reactor (the positive electrode panel has a patterned adsorption layer and the negative electrode panel does not have an adsorption layer). FIG. 3 shows a cross-sectional view of the electrode panel shown in FIG. 2 along a first direction. FIG. 4 is a side view showing the electrode panel of the second embodiment of the plasma reactor (the positive electrode panel has a patterned adsorption layer and the negative electrode panel has an adsorption layer over the entire surface). FIG. 5 is a side view showing the electrode panel of the third embodiment of the plasma reactor (the positive electrode panel and the negative electrode panel are provided with patterned adsorption layers, and the adsorption layers face each other). FIG. 6 is a side view showing the electrode panel of the fourth embodiment of the plasma reactor (the positive electrode panel and the negative electrode panel are provided with patterned adsorption layers, and the adsorption layers do not face each other). 7A and 7B are schematic diagrams showing modifications of the pattern of the adsorption layer in the plasma reactor. FIG. 7A shows an electrode panel in which the adsorption layer is formed in a border pattern, and FIG. 7B shows the adsorption layer in a check pattern. FIG. 7C shows an electrode panel in which the adsorption layer is formed in a dot pattern, and FIG. 7D shows an electrode panel in which the adsorption layer is formed in a wide stripe pattern. 8A and 8B are photographs showing the discharge state of the plasma reactor of Example 1. FIG. 8A shows the discharge state when dry, and FIG. 8B shows the discharge state when wet. 9A and 9B are photographs showing the discharge state of the plasma reactor of Comparative Example 1. FIG. 9A shows the discharge state when dry, and FIG. 9B shows the discharge state when wet.

1. Outline of Plasma Reactor A first embodiment of the plasma reactor of the present invention will be described in detail with reference to FIGS. 1 to 3. FIG.

As shown in FIG. 1, plasma reactor 1 is included in exhaust system 103 of vehicle 100 .

The vehicle 100 includes an engine 101, an electric system including a battery 102, an intake system (not shown) for drawing air into the engine 101, a fuel injection system (not shown) for supplying fuel to the engine 101, and exhaust from the engine 101. and an exhaust system 103 for

The exhaust system 103 includes an exhaust pipe 104 and the plasma reactor 1 .

The exhaust pipe 104 is a pipe for exhausting the exhaust gas discharged from the engine 101 . The exhaust pipe 104 is connected to the engine 101 .

The plasma reactor 1 is interposed in the middle of the exhaust pipe 104 . The plasma reactor 1 is electrically connected to the battery 102 via the power wiring 105 . The plasma reactor 1 generates plasma and decomposes harmful components contained in the exhaust gas when power is supplied from the battery 102 through the power supply wiring 105, which will be described later in detail. Exhaust gas that has passed through the plasma reactor 1 is discharged outside the vehicle through an exhaust pipe 104 .

2. Details of Plasma Reactor As shown in FIG. 1, a plasma reactor 1 comprises a casing 2 and a plurality of electrode panels 3 .

(1) Casing The casing 2 has a hollow cylindrical shape. Casing 2 has an inlet 2A and an outlet 2B. Exhaust gas discharged from the engine 101 passes through the exhaust pipe 104 and flows into the casing 2 from the inlet 2A. Exhaust gas that has passed through the casing 2 is discharged from the outlet 2B.

(2) Electrode Panels A plurality of electrode panels 3 are arranged inside the casing 2 .

Each of the multiple electrode panels 3 extends in a first direction from the entrance 2A to the exit 2B. Each of the plurality of electrode panels 3 has a flat plate shape. The plurality of electrode panels 3 are arranged at intervals in a second direction perpendicular to the first direction.

The distance between two adjacent electrode panels 3 is, for example, 0.10 mm or more, preferably 0.30 mm or more, and for example, 1.00 mm or less, preferably 0.80 mm or less.

As shown in FIGS. 2 and 3, the plurality of electrode panels 3 includes positive panels 3A and negative panels 3B. The positive electrode panel 3A is the electrode panel 3 electrically connected to the positive electrode of the battery 102 (see FIG. 1). The negative electrode panel 3B is the electrode panel 3 electrically connected to the negative electrode of the battery 102 . The positive electrode panel 3A and the negative electrode panel 3B are arranged to face each other in the second direction. The positive electrode panels 3A and the negative electrode panels 3B are arranged alternately. The positive electrode panel 3A and the negative electrode panel 3B have the same structure. That is, each of the plurality of electrode panels 3 has the same structure. Specifically, each of the plurality of electrode panels 3 includes a dielectric layer 4 and a conductor layer 5, and also includes an adsorption layer 6 in a predetermined region described later. 2, the conductor layer 5 is omitted.

Dielectric layer 4 extends in a first direction. Dielectric layer 4 has a flat plate shape. The dielectric layer 4 is made of, for example, ceramics such as aluminum oxide. Dielectric layer 4 has a first surface S1 and a second surface S2. The first surface S1 is a surface on one side in the second direction. The second surface S2 is the surface on the other side in the second direction.

The thickness (length in the second direction) of the dielectric layer 4 is, for example, 0.20 mm or more, preferably 0.30 mm or more, and for example, 3.00 mm or less, preferably 2.00 mm or less.

The conductor layer 5 is made of metal such as tungsten, and is electrically connected to the power supply wiring 105 (see FIG. 1).

The conductor layer 5 has a sheet shape extending in the first direction. Also, the conductor layer 5 is arranged inside the dielectric layer 4 over the entire dielectric layer 4 in the first direction.

Specifically, the conductor layer 5 is pattern-shaped as necessary and arranged substantially in the center of the dielectric layer 4 in the second direction over the entire dielectric layer 4 in the first direction. As a result, the thickness of the conductor layer 5 covered by the dielectric layer 4 (thickness from the conductor layer 5 to the surface of the dielectric layer 4) can be ensured, and the durability of the electrode panel 3 can be ensured.

The adsorption layer 6 is an inorganic layer for adsorbing hydrocarbons (HC), and is made of an HC adsorbent. Examples of HC adsorbents include inorganic materials such as alumina and zeolite. These HC adsorbents can be used alone or in combination of two or more. Zeolite is preferably used as the HC adsorbent.

Such an adsorption layer 6 is formed on the facing surface of at least one electrode panel 3 (for example, the positive electrode panel 3A) inside the pair of electrode panels 3 facing each other in the second direction.

More specifically, in FIGS. 2 and 3, the positive electrode panel 3A and the negative electrode panel 3B on the upper side of the paper face each other in the second direction. An adsorption layer 6 is provided on the surface (first surface S1) of the positive electrode panel 3A as the electrode panel 3 on one side inside in the opposing direction.

Moreover, the adsorption layer 6 has a predetermined pattern.

That is, the adsorption layer 6 is formed in a pattern such that a region where the adsorption layer 6 is arranged and a region where the adsorption layer 6 is not arranged are repeated regularly or irregularly.

The pattern is not particularly limited, but examples include a stripe pattern (a vertical stripe pattern along the longitudinal direction of the electrode panel 3), a border pattern (a horizontal stripe pattern along the width direction of the electrode panel 3), a check pattern (lattice pattern), and a dot pattern. (polka dot pattern). Moreover, it is also possible to employ a combination of a plurality of patterns. The pattern of the adsorption layer 6 is preferably a stripe pattern. The pattern dimensions (width, pitch, etc.) of the adsorption layer 6 are not particularly limited, and are appropriately set according to the purpose and application.

As an example of the adsorption layer 6, FIGS. 2 and 3 show the adsorption layer 6 having a stripe pattern along the first direction (exhaust gas flow direction).

Then, by patterning the adsorption layer 6, the adsorption region α as the region where the adsorption layer 6 is arranged and the dielectric layer 4 are exposed without the adsorption layer 6 being arranged on the surface of the positive electrode panel 3A. The exposed area β as the exposed area is respectively partitioned.

2 and 3, the adsorption layer 6 is not formed on the back surface (second surface S2) of the negative electrode panel 3B as the electrode panel 3 on the other side, and the dielectric layer 4 is exposed. That is, the entire back surface (second surface S2) of the negative electrode panel 3B on the upper side of the paper surface is the exposed region β.

In addition to the above, in FIGS. 2 and 3, the positive electrode panel 3A and the negative electrode panel 3B on the lower side of the paper face each other in the second direction. An adsorption layer 6 having a predetermined pattern is provided on the back surface (second surface S2) of the positive electrode panel 3A as the electrode panel 3 on one side inside in the facing direction.

More specifically, the adsorption layer 6 is pattern-formed on the back surface (second surface S2) of the positive electrode panel 3A as the electrode panel 3 on one side. As a result, on the back surface of the positive electrode panel 3A, there are an adsorption region α as a region where the adsorption layer 6 is arranged and an exposed region β as a region where the adsorption layer 6 is not arranged and the dielectric layer 4 is exposed. , respectively.

In FIGS. 2 and 3, the adsorption layer 6 is not formed on the surface (first surface S1) of the negative electrode panel 3B as the electrode panel 3 on the other side, and the dielectric layer 4 is exposed. That is, the entire surface (first surface S1) of the negative electrode panel 3B on the lower side of the paper is the exposed region β.

Thus, in the plasma reactor 1, in the pair of electrode panels 3 facing each other in the second direction, the electrode panel 3 (positive electrode panel 3A) on one side faces the electrode panel 3 (negative electrode panel 3B) on the other side. An adsorption layer 6 is patterned on the surface.

Thus, the electrode panel 3 (positive electrode panel 3A) on one side has an adsorption area α with the adsorption layer 6 and an exposed area β without the adsorption layer 6 . Further, the electrode panel 3 (negative electrode panel 3B) on the other side has an exposed region β where the adsorption layer 6 is not provided.

The method of forming the adsorption layer 6 is not particularly limited, but for example, a slurry containing an HC adsorbent (such as zeolite) is applied to the surface of the dielectric layer 4 of the electrode panel 3 so as to form the predetermined pattern. , dried and, if necessary, calcined. As a result, the adsorption layer 6 covering the dielectric layer 4 is formed in the predetermined pattern.

The thickness of the adsorption layer 6 is, for example, 0.01 mm or more, preferably 0.05 mm or more, and for example, 0.2 mm or less, preferably 0.1 mm or less.

3. Exhaust Gas Purification In vehicle 100 , exhaust gas discharged from engine 101 passes through exhaust pipe 104 and is supplied to plasma reactor 1 .

At this time, harmful components (eg, hydrocarbons (HC), etc.) contained in the exhaust gas that has flowed into the plasma reactor 1 are adsorbed by the adsorption layer 6 .

Then, as shown in FIG. 1, when power is supplied from the battery 102 to the plasma reactor 1 through the power wiring 105, discharge occurs between the first surface S1 and the second surface S2 of each electrode panel 3. occur.

Thereby, the gas between each electrode panel 3 becomes a plasma state. That is, plasma is generated within the plasma reactor 1 .

Then, harmful components (eg, hydrocarbons (HC), etc.) contained in the exhaust gas that has flowed into the plasma reactor 1 are decomposed (plasma decomposition) by the plasma within the plasma reactor 1 .

4. Functions and Effects The plasma reactor 1 may be required to have improved discharge performance.

More specifically, for example, in the plasma reactor 1, condensation of water vapor may occur due to a decrease in the internal temperature, etc., and the resulting moisture may wet the adsorption layer 6 and increase the conductivity. be. When the conductivity of the adsorption layer 6 increases, it becomes difficult to transfer electrons between the electrode panels 3, so that it becomes difficult to generate electric discharge between the electrode panels 3, resulting in a problem that the HC decomposition performance by plasma is lowered. . Therefore, it is required to improve the discharge performance of the plasma reactor 1 and obtain excellent HC decomposition performance.

On the other hand, in the plasma reactor 1, at least one of the electrode panels 3 facing each other (positive electrode panel 3A) faces the other electrode panel (negative electrode panel 3B). , an adsorption layer 3 for adsorbing hydrocarbons, and the adsorption layer 3 is formed in a predetermined pattern. That is, the adsorption layer 6 is patterned on at least one side of the electrode panel (positive electrode panel 3A), and the adsorption layer 6 is formed in a region (adsorption region α) and in which the adsorption layer 6 is not formed. regions (exposed regions β) are arranged as a predetermined pattern. In such a plasma reactor 1, since the adsorption layer 6 is patterned on the surface of the electrode panel 3 (positive electrode panel 3A), the adsorption layer 6 is formed on the entire surface of the electrode panel 3 (positive electrode panel 3A). The edge of the adsorption layer 6 can be increased as compared with the case where the adsorption layer 6 is provided. At the edges of the adsorption layer 6, electron transfer between the electrode panels 3 is likely to occur. Therefore, by increasing the edge of the adsorption layer 6, the discharge between the electrode panels 6 can be promoted.

Furthermore, in the plasma reactor 1 described above, the water absorption rate of the region where the adsorption layer 6 is not formed (exposed region β) is lower than the water absorption rate of the region where the adsorption layer 6 is formed (adsorption region α). , with excellent drying efficiency. Therefore, for example, even when moisture condensation occurs inside the plasma reactor 1 and causes the wetting of the adsorption layer 6 and the deterioration of the discharge performance, the region where the adsorption layer 6 is not formed (exposed region β) is dried. By setting the state, deterioration of the discharge performance can be suppressed.

As a result, according to the plasma reactor 1 described above, excellent discharge performance and HC decomposition performance can be obtained.

5. Modifications In the first embodiment described above, as shown in FIGS. 2 and 3, the adsorption layers 6 are patterned on both sides of the positive electrode panel 3A of the pair of electrode panels 3 facing each other in the second direction. Although the adsorption layer 6 is not formed on the negative electrode panel 3B, the portion where the adsorption layer 6 is formed is not limited to the above.

That is, it is sufficient that the adsorption layer 6 is pattern-formed on the surface of at least one of the pair of electrode panels 3 facing each other. For example, as shown in FIG. 4 as the second embodiment. Additionally, both the positive electrode panel 3A and the negative electrode panel 3B can be provided with the adsorption layer 6 . In such a case, the positive electrode panel 3A and/or the negative electrode panel 3B may have the adsorption layer 6 only on the first surface S1 (one side surface), and may be provided on the second surface S2 (the other side surface). It may be provided only, or may be provided on both sides. Note that FIG. 4 shows a configuration in which both the positive electrode panel 3A and the negative electrode panel 3B are provided with the adsorption layers 6 on both the first surface S1 and the second surface S2.

At least one of the adsorption layers 6 should have a predetermined pattern. For example, among the adsorption layer 6 formed on the positive electrode panel 3A and the adsorption layer 6 formed on the negative electrode panel 3B, at least one adsorption layer 6 may be formed in a predetermined pattern. Layer 6 may not be formed in a predetermined pattern.

More specifically, as shown in FIG. 4, only the adsorption layer 6 of the positive electrode panel 3A may have the predetermined pattern, and the adsorption layer 6 of the negative electrode panel 3B may not have the predetermined pattern.

Moreover, as shown in FIG. 5 as a third embodiment, the adsorption layers 6 may have a predetermined pattern in both the positive electrode panel 3A and the negative electrode panel 3B.

In such a case, as shown in FIG. 5, the adsorption layer 6 (adsorption region α) of the positive electrode panel 3A and the adsorption layer 6 (adsorption region α) of the negative electrode panel 3B face each other in the second direction. may In such a case, as shown in FIG. 5, for example, the exposed region β of the positive electrode panel 3A and the exposed region β of the negative electrode panel 3B face each other in the second direction.

In addition, as shown in FIG. 6 as a fourth embodiment, the adsorption layer 6 (adsorption region α) of the positive electrode panel 3A and the adsorption layer 6 (adsorption region α) of the negative electrode panel 3B must not face each other. good too. In such a case, as shown in FIG. 6, for example, the exposed region β of the positive electrode panel 3A and the adsorption region α of the negative electrode panel 3B face each other in the second direction. Also, the adsorption area α of the positive electrode panel 3A and the exposed area β of the negative electrode panel 3B face each other in the second direction. The exposed region β of the positive electrode panel 3A and the exposed region β of the negative electrode panel 3B do not face each other in the second direction.

Furthermore, although not shown, a portion of the adsorption layer 6 (adsorption region α) of the positive electrode panel 3A and a portion of the adsorption layer 6 (adsorption region α) of the negative electrode panel 3B may face each other.

Furthermore, the pattern of the adsorption layer 6 is not limited to the stripe pattern described above, and various patterns can be formed. For example, as shown in FIG. 7A, the adsorption layer 6 may be formed as a border pattern, for example, as shown in FIG. 7B, the adsorption layer 6 may be formed as a check pattern. As shown in FIG. 7C, the adsorption layer 6 may be formed as a dot pattern. Furthermore, the pattern dimensions (width, pitch, etc.) of the adsorption layer 6 can be set arbitrarily. For example, as shown in FIG. 7D, the adsorption layer 6 may be formed in a wide stripe pattern.

In the above-described embodiment as well, at least one electrode panel 3 is provided with the adsorption layer 6 having a predetermined pattern for adsorbing hydrocarbons on the surface facing the electrode panel 3 on the other side. Performance and HC cracking performance can be obtained.

EXAMPLES Examples and comparative examples are shown below to describe the present invention more specifically. In addition, the present invention is not limited to Examples and Comparative Examples. In addition, specific numerical values such as the mixing ratio (content ratio), physical property values, and parameters used in the following description are the corresponding mixing ratios ( Content ratio), physical properties, parameters, etc. be able to.

"Parts" and "%" are based on mass unless otherwise specified.

Example 1
A zeolite slurry (dry weight of 90% by mass of zeolite and 10% by mass of binder) was applied in a stripe pattern on both sides of the positive electrode panel of the plasma reactor, and baked at 450° C. for 1 hour to obtain adsorption of zeolite. A layer (0.075 μm thick) was formed.

Next, in order to observe the discharge surface, the positive electrode panel and the glass electrode were alternately stacked with an interval of 0.5 mm in the casing of the transparent plasma reactor. No adsorption layer was formed on the glass electrode corresponding to the negative electrode panel.

After that, the plasma reactor was operated to confirm the discharge state during drying.

Also, the positive electrode panel was taken out from the plasma reactor, and 1.0 to 2.0 mL of tap water was dripped onto the adsorption layer to wet it. After that, the plasma reactor was operated to confirm the discharge state when wet.

FIG. 8A shows a photograph of the discharge state when dry, and FIG. 8B shows a photograph of the discharge state when wet. Note that FIG. 8 is a side view of the plasma reactor, and white portions indicate light emission due to discharge.

Comparative example 1
The plasma reactor was operated in the same manner as in Example 1, except that the adsorption layer made of zeolite was not formed into a stripe pattern, but was formed on the entire surface of the positive electrode panel, and the discharge state was confirmed.

FIG. 9A shows a photograph of the discharge state when dry, and FIG. 9B shows a photograph of the discharge state when wet. FIG. 9 is also a side view of the plasma reactor, and the white portion indicates light emission due to discharge.

REFERENCE SIGNS LIST 1 plasma reactor 2 casing 2A inlet 2B outlet 3 electrode panel 4 dielectric layer 5 conductor layer 6 adsorption layer

Claims (1)

a casing having an inlet through which exhaust gases flow in and an outlet through which exhaust gases flow out;
a plurality of electrode panels disposed within the casing, extending in a first direction from the inlet toward the outlet, and spaced apart from each other in a second direction orthogonal to the first direction;
In a pair of electrode panels facing each other in the second direction,
The electrode panel on at least one side has an adsorption layer that adsorbs hydrocarbons on the surface facing the electrode panel on the other side,
The electrode panel having an adsorption layer includes an adsorption area where the adsorption layer is arranged and an exposed area where the adsorption layer is not arranged,
The adsorption layer has a predetermined pattern, and the adsorption region and the exposure region are repeated regularly or irregularly.
A plasma reactor characterized by:

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