JP7258577B2 - 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, in a plasma reactor, condensation of water vapor may occur due to a decrease in internal temperature, etc., and the resulting moisture may wet the hygroscopic HC adsorbent (adsorption layer) and increase the conductivity. be.

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 provides a plasma reactor that exhibits excellent discharge performance between electrode panels and excellent HC decomposition performance even when the adsorption layer is wet.

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, and a pair of the electrode panels facing each other in the second direction, wherein the electrode panel on one side and the electrode panel on the other side The opposing surface has an adsorption area with an adsorption layer that adsorbs hydrocarbons, and the electrode panel on the other side has an exposed area without the adsorption layer on the surface facing the electrode panel on the one side. , the electrode panel includes a plasma reactor arranged such that the adsorption area and the exposure area are opposed to each other.

In the plasma reactor of the present invention, of the electrode panels facing each other, one electrode panel has an adsorption area with an adsorption layer, and the other electrode panel has an exposed area without an adsorption layer. The electrode panel is arranged such that the attraction area and the exposure area are opposed to each other.

If the adsorption area of the electrode panel on one side and the exposed area of the electrode panel on the other side face each other, even if the adsorption layer of the electrode panel on one side gets wet, the adsorption layer on the other side Since it faces the exposed surface of the electrode panel, it is possible to exchange electrons well therebetween.

As a result, the plasma reactor of the present invention can achieve excellent discharge performance between electrode panels and excellent HC decomposition performance even when the adsorption layer is wet.

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 side view showing the electrode panel of the first embodiment of the plasma reactor (positive electrode panel having adsorption layers on both sides). FIG. 3 is a side view showing the electrode panel of the second embodiment of the plasma reactor (the positive electrode panel and the negative electrode panel have an adsorption layer on one side). FIG. 4 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 have an adsorption layer on the other side). FIG. 5 shows a fourth embodiment of the plasma reactor (the positive electrode panel has adsorption layers on one upstream side and the other downstream side, and the negative electrode panel has adsorption layers on the other upstream side and one downstream side). ) is a side view showing the electrode panel. FIG. 6 is a side view showing the electrode panel of the fifth embodiment of the plasma reactor (the form in which the adsorption layers are patterned in the positive electrode panel and the negative electrode panel). 7A and 7B are photographs showing the discharge state of the plasma reactor of Example 1. FIG. 7A shows the discharge state when dry, and FIG. 7B shows the discharge state when wet. 8A and 8B are photographs showing the discharge state of the plasma reactor of Comparative Example 1. FIG. 8A shows the discharge state when dry, and FIG. 8B 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 and 2. 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 FIG. 2, 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.

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 arranged substantially in the center of the dielectric layer 4 in the second direction in 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.

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

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.

Such an adsorption layer 6 is arranged on at least part of the surface of one electrode panel 3 inside the pair of electrode panels 3 facing each other in the second direction in the facing direction, and covers the dielectric layer 4. . As a result, an adsorption region α is defined as a region in which the adsorption layer 6 is formed. Moreover, the adsorption layer 6 is not arranged on at least a part of the surface of the electrode panel 3 on the other side, and the dielectric layer 4 is exposed. As a result, an exposed region β as a region where the dielectric layer 4 is exposed is defined.

More specifically, in FIG. 2, 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 formed on the entire surface (first surface S1) of the positive electrode panel 3A as the electrode panel 3 on one side on the inside in the opposing direction. That is, the entire surface (first surface S1) of the positive electrode panel 3A is the adsorption area α.

Moreover, 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.

Also, in FIG. 2, 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 is formed on the entire rear surface (second surface S2) of the positive electrode panel 3A as the electrode panel 3 on one side inside in the facing direction. That is, the entire back surface (second surface S2) of the positive electrode panel 3A is the adsorption area α.

Moreover, 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. The surface has an adsorption area α with an adsorption layer 6 . Further, the electrode panel 3 (negative electrode panel 3B) on the other side has an exposed region β without the adsorption layer 6 on the surface facing the electrode panel 3 (positive electrode panel 3A) on the one side.

These electrode panels 3 are arranged in the casing 2 such that 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.

That is, the positive electrode panel 3A and the negative electrode panel 3B are arranged so that the projection surface of the adsorption region α of the positive electrode panel 3A and the projection surface of the exposed region β of the negative electrode panel 3B overlap each other in the projection plane of them in the thickness direction. , is placed. Thereby, the adsorption region α and the exposed region β face each other in the second direction.

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

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 Usually, 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 electrical conductivity. 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. .

On the other hand, in the plasma reactor 1 described above, among the electrode panels 3 facing each other, the electrode panel 3 on one side has an adsorption area α having an adsorption layer 6 , and the electrode panel 3 on the other side has an adsorption layer 6 . has an exposed area β that has no The electrode panel 3 is arranged such that the adsorption area α and the exposed area β face each other.

Thus, if the adsorption area α of the electrode panel 3 on one side and the exposed area β of the electrode panel 3 on the other side face each other, when the adsorption layer 6 of the electrode panel 3 on the one side is wetted, Also, since the adsorption layer 6 faces the exposed surface of the dielectric layer 4 of the electrode panel 3 on the other side, electrons can be transferred well between them.

As a result, even when the adsorption layer 6 is wet, the plasma reactor 1 described above is excellent in discharge between the electrode panels 3, and excellent HC decomposition performance can be obtained.

5. Modification In the first embodiment described above, as shown in FIG. 2, of the pair of electrode panels 3 facing each other in the second direction, the adsorption layer 6 is formed only on the positive electrode panel 3A, and the adsorption layer 6 is formed on the negative electrode panel 3B. Although the adsorption layer 6 is not formed, the part in which the adsorption layer 6 is formed is not limited to the above.

That is, the adsorption layer 6 is formed on the surface of at least one of the electrode panels 3 of the pair of electrode panels 3 facing each other in the second direction, and the adsorption region α is defined. The surface of the panel 3 may be divided into exposed regions β where the adsorption layer 6 is not provided, and the electrode panel 3 may be arranged so that they face each other.

More specifically, for example, as shown in FIG. 3 as a second embodiment, both the positive electrode panel 3A and the negative electrode panel 3B can be provided with the adsorption layer 6 over the entire first surface S1. In such a case, the adsorption layer 6 is not provided on the second surface S2 of both the positive panel 3A and the negative panel 3B, and the dielectric layer 4 is exposed. That is, the entire first surface S1 of the positive electrode panel 3A and the negative electrode panel 3B is the adsorption area α, and the entire second surface S2 of the positive electrode panel 3A and the negative electrode panel 3B is the exposed area β, and they are arranged to face each other. , the electrode panel 3 is arranged.

Also, for example, both the positive electrode panel 3A and the negative electrode panel 3B can be provided with the adsorption layer 6 over the entire second surface S2, as shown in FIG. 4 as a third embodiment. In such a case, the adsorption layer 6 is not provided on the first surface S1 of both the positive panel 3A and the negative panel 3B, and the dielectric layer 4 is exposed. In other words, the entire second surface S2 of the positive electrode panel 3A and the negative electrode panel 3B is the adsorption area α, and the entire first surface S1 of the positive electrode panel 3A and the negative electrode panel 3B is the exposed area β, which are arranged to face each other. , the electrode panel 3 is arranged.

Further, for example, as shown in FIG. 5 as a fourth embodiment, the positive electrode panel 3A and the negative electrode panel 3B have a first surface S1 on the upstream side in the first direction and a second surface S2 on the downstream side in the first direction. , an adsorption layer 6 can also be provided. In such a case, the positive electrode panel 3A and the negative electrode panel 3B are not provided with the adsorption layer 6 on the second surface S2 of the upstream portion in the first direction and the first surface S1 of the downstream portion in the first direction. Dielectric layer 4 is exposed. That is, the first surface S1 of the upstream portion in the first direction and the second surface S2 of the downstream portion in the first direction of the positive electrode panel 3A and the negative electrode panel 3B serve as the adsorption region α, and the first direction upstream The second surface S2 of the side portion and the first surface S1 of the downstream portion in the first direction are the exposed region β, and the electrode panel 3 is arranged such that they face each other.

Although not shown, contrary to the above, the first surface S1 of the upstream portion in the first direction and the second surface S2 of the downstream portion in the first direction of the positive electrode panel 3A and the negative electrode panel 3B are exposed regions. β, and the second surface S2 on the upstream side in the first direction and the first surface S1 on the downstream side in the first direction are the adsorption areas α, and they are arranged to face each other. good.

In addition, for example, as shown in FIG. 6 as a fifth embodiment, the adsorption layer 6 may be patterned in each of the positive electrode panel 3A and the negative electrode panel 3B.

More specifically, in the fifth embodiment, the adsorption layer 6 forms a striped pattern with an appropriate width as a predetermined pattern along a direction perpendicular to the first direction and the second direction (the depth direction of the paper surface). are formed on both sides of the positive electrode panel 3A and the negative electrode panel 3B.

As a result, on both surfaces of the positive electrode panel 3A and the negative electrode panel 3B, striped adsorption regions α are defined, and slit-shaped exposed regions β are defined, and the electrode panels 3 are arranged such that they face each other. . The pattern of the adsorption layer 6 is not limited to the above, and any pattern such as a dot pattern or check pattern can be adopted.

In the second to sixth embodiments as described above, the adsorption area α of the electrode panel 3 on one side and the exposed area β of the electrode panel 3 on the other side face each other. Therefore, even when the adsorption layer 6 of the electrode panel 3 on one side is wet, the adsorption layer 6 faces the exposed surface of the dielectric layer 4 of the electrode panel 3 on the other side, so that electrons are transferred between them. Able to give and receive well.

As a result, even when the adsorption layer 6 is wet, the plasma reactor 1 described above is excellent in discharge between the electrode panels 3, and excellent HC decomposition 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 to both sides of the positive electrode panel of the plasma reactor and baked at 450° C. for 1 hour to form an adsorption layer made of zeolite (0.075 μm thick). ) was formed. On the other hand, no adsorption layer was formed on the negative electrode panel.

Next, in the casing of the plasma reactor, the positive electrode panel and the negative electrode panel were alternately stacked with an interval of 0.5 mm. After that, the plasma reactor was operated to confirm the discharge state during drying.

Further, tap water was sprayed 30 times from the inlet to the outlet of the plasma reactor, and left for 15 minutes. After that, the plasma reactor was operated to confirm the discharge state when wet.

A photograph of the discharge state when dry is shown in FIG. 7A, and a photograph of the discharge state when wet is shown in FIG. 7B. Note that FIG. 7 is a side view of the plasma reactor, and the white portion indicates 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 layers were formed on both sides of the positive electrode panel and the adsorption layers were formed on both sides of the negative electrode panel, and the discharge state was confirmed.

FIG. 8A shows a photograph of the discharge state when dry, and FIG. 8B shows a photograph of the discharge state when wet. FIG. 8 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 α adsorption region β exposure region

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;
Each of the plurality of electrode panels includes, on both sides,
an adsorption region comprising an adsorption layer that adsorbs hydrocarbons;
an exposed region without the adsorption layer;
and
In a pair of electrode panels facing each other in the second direction ,
The plasma reactor, wherein the electrode panel is arranged such that the adsorption area and the exposure area are opposed to each other.

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