JP3398779B2 - Plasma processing gas processing equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is intended to treat exhaust gas emitted from a combustion furnace in combustion treatment of municipal waste and industrial waste, exhaust gas emitted from an industrial boiler, and exhaust gas emitted from an automobile in a tunnel or an indoor parking lot. The present invention relates to a plasma-type exhaust gas purifying apparatus and a gas treatment apparatus such as a plasma-type ozone generating apparatus that generates ozone by using air or oxygen as a raw material.

[0002]

2. Description of the Related Art A reactor having at least one discharge electrode and at least one counter electrode alternately provided inside a flue, and a high-voltage pulse generating power source connected to both electrodes are provided between both electrodes. Exhaust gas purification in which non-equilibrium plasma is generated by continuously applying high voltage pulse to the exhaust gas, and while the exhaust gas passes through the reactor, the harmful gas components in the exhaust gas are converted into a form that is easy to collect or a harmless form A plasma method gas processing device for plasma has been conventionally known (see Japanese Patent Laid-Open No. 63-500020). It is known that the discharge electrode is a wire type and the counter electrode is a plate type. Then, one plate unit is formed by lengthening the plate in the exhaust gas passage direction and installing a large number of wires, and scaling up by arranging a plurality of electrode unit units in a direction perpendicular to the exhaust gas passage direction. , So that a large amount of exhaust gas can be processed. However, the plasma method gas treatment equipment using these electrodes is characterized in that plasma is generated intermittently in the length direction of the wire, so that the generated plasma has a sparse portion and the contact efficiency between plasma and exhaust gas is high. There was a problem that was not good.

Therefore, the present applicant has previously proposed that, as shown in FIG. 3, a metal plate (15) and a plurality of discharge needles supported by the metal plate (15).
Discharge electrode (13) provided with (16) and flat counter electrode (14)
And a high-voltage pulse generation power supply (12) connected between both electrodes (13) (14), by continuously applying a high-voltage pulse between both electrodes (13) (14) A non-equilibrium plasma (21) is generated and the gas to be treated (18) is placed between both electrodes (3) and (4).
Has proposed a plasma method gas treatment apparatus for purifying exhaust gas that passes through the exhaust gas (Japanese Patent Application No. 7-4374).
6). According to this plasma method gas processing device, a strong electric field is generated at the tip of the discharge needle, and discharge easily occurs between the electrodes.
Moreover, since the discharge is performed between each discharge needle and the flat plate, the discharge range can be widened by increasing the number of discharge needles, which is also suitable for scale-up. . The discharge electrode provided with the plurality of discharge needles is obtained by forming holes in a metal flat plate, manufacturing a necessary number of needles, and welding the needles one by one to the holes of the metal plate.

[0004]

By the way, in a gas treatment apparatus using plasma, it is important how high power can be applied in a certain space without squeezing between electrodes. The maximum amount of electric power that can be applied between the electrodes differs depending on the shape of the electrodes, and there is a demand for an electrode that can apply even higher electric power than a discharge electrode having a plurality of discharge needles.

Further, whether or not the electrode is suitable for mass production is also important in terms of scale-up, but the above conventional process for obtaining a discharge electrode having a plurality of discharge needles is complicated and is not suitable for mass production. There was also a problem.

The object of the present invention is, as compared with the conventional one,
It is an object of the present invention to provide a plasma method gas treatment apparatus capable of applying high power between electrodes and suitable for mass production.

[0007]

A plasma method gas treatment apparatus according to the present invention purifies exhaust gas by continuously applying a high voltage pulse between a discharge electrode and a counter electrode to generate non-equilibrium plasma. In a plasma method gas treatment apparatus for generating ozone using oxygen or oxygen as a raw material, the discharge electrode is composed of a metal plate and a wire mesh supported by the metal plate and bent so that both edges project toward the opposite electrode. It is characterized by that.

As the wire mesh, it is possible to use a ready-made stainless steel wire.
A discharge electrode is obtained by bending and then fixing to a metal plate.

A plurality of wire nets may be arranged in parallel.

The height of the comb portion is 0.1 mm or more, the mesh spacing of the wire mesh is in the range of 0.1 mm to 20 mm, and the distance between the tip of the comb portion and the counter electrode is 1 mm to 50 mm. It is preferably within the range. The height of the comb-shaped portion is more preferably 1 mm or more. For example, in order to make the height of the comb-shaped portion 1 mm or more by using a wire mesh having a mesh interval of less than 1 mm, in the wire constituting the wire mesh, the wire is at the tip of the bent portion and the metal plate is It suffices to pull out several parallel wires.

[0011]

1 and 2 show a plasma processing gas processing apparatus according to the present invention. As shown in FIG.
The plasma method gas treatment device consists of a discharge electrode (3), a counter electrode (4), and a high-voltage pulse power supply connected to both electrodes (3) and (4).
(2) and are provided.

The counter electrode (4) is a plate type. The discharge electrode (3) is composed of a metal plate (5) having the same area as the counter electrode (4) and a wire mesh (6) provided on the metal plate (5). Wire mesh (6)
Is bent so that both edges thereof project in the direction of the counter electrode, and has a U-shaped cross section. The wire mesh (6)
It is made of stainless steel from the viewpoint of corrosion resistance.

Referring to FIG. 2, preferred dimensions of the wire mesh (6) are shown below.

The height of the bent part (6a) of the wire mesh (6) does not affect the plasma generation, and the comb-shaped part (7) formed at the tip of the bent part (6a) of the wire mesh (6). Height affects the plasma generation. The height H of the comb-shaped portion (7) is preferably 0.1 mm or more. The mesh interval P of the wire net (6) is preferably in the range of 0.1 mm to 20 mm. The distance D between the tip of the comb-like portion (7) and the counter electrode (4) is preferably in the range of 1 mm to 50 mm. With such a range, high electric power can be applied between the electrodes.

Between the discharge electrode (3) and the counter electrode (4),
Non-equilibrium plasma (pulse streamer corona) (11) is generated by the application of high voltage pulse. The plasma (11) has a conical shape and is densely present between the comb-shaped portion (7) at the tip of the wire mesh bent portion (6a) and the counter electrode (4). Comb (7) at the tip of part (6a)
It does not exist between the discharge electrode and the discharge electrode (3). The gas (8) to be treated is passed between the electrodes (3) and (4).

In order to scale up the apparatus with respect to an increase in the gas amount, a plurality of discharge electrodes (3) and a plurality of counter electrodes (4) arranged parallel to the flow direction of the gas (8) are used. )
It can be easily performed by increasing the flow direction of and the direction perpendicular thereto. Further, a plurality of wire meshes (6) may be arranged in parallel on one metal plate (5), or the metal wire mesh (6) may be
A wire mesh partition parallel to the bent end portion (6a) may be added.

This plasma method gas treatment apparatus is used, for example, for exhaust gas purification. In this case, NOx and S
The treated exhaust gas (8) containing Ox comes into contact with the plasma (11) while passing between the electrodes, whereby various radicals are generated in the exhaust gas (8). Exhaust gas by this radical (8)
The NOx and SOx therein are oxidized and converted into NO ₂ and SO ₃ . Exhaust gas containing harmful gas components changed in this way
(8) moves to a collecting section (not shown) provided downstream.

The plasma method gas treatment apparatus is also used for ozone production. In this case, the source gas (8) made of oxygen or air comes into contact with the plasma (11) while passing between the electrodes, whereby the source gas (8) is radicalized to generate ozone.

[0019]

EXAMPLES Tables 1 and 2 below show the discharge electrodes of the present invention.
By using (3) and the discharge electrode (13) obtained by the conventional manufacturing method, the generation efficiency of the pulse plasma (11) (21) and the discharge electrode
(3) The results of comparing the production aspects of (13) are shown. In Tables 1 and 2, the 2 mm sharp discharge needle (16) is attached to the metal plate (1
Fig. 5 shows the conventional one attached to, where is a 1 mm mesh wire mesh fixed to a metal plate (5), both sides of the wire mesh are bent so that the cross section is U-shaped, and the cross section is used as an opposing electrode. It is aimed at. And both discharge electrodes
The distance between (3) (13) and the counter electrodes (4) (14) is 25 mm, and the area of the metal plates (5) (15) of the discharge electrodes (3) (13) is 100 cm.
It is said to be ² .

[0020]

[Table 1] Table 1 compares the generated power of plasma between the electrodes (3), (13) and (14). From this table, it can be seen that higher power is obtained by the present invention.

[0021]

[Table 2] This Table 2 compares the production process of each discharge electrode (3) (13). Here, the area of the metal plates (5) (15) is 1
m ² and pitch were both 20 mm. From Table 2,
In the conventional one, it takes a lot of time to drill and weld,
On the other hand, according to the present invention, it is understood that the ready-made wire netting is simply cut into a required size, bent, and then fixed to the metal plate, which enables mass production.

In the above description, the metal plate (5) of the discharge electrode (3) and the counter electrode (4) are both flat plates, but they may have an arc cross section. The above conditions can be applied even in the case of a tubular shape.

[0023]

According to the plasma method gas treatment apparatus of the present invention, the wire mesh is cut to a required size and then bent,
Since the discharge electrode can be obtained by fixing it to a metal plate, mass production is possible.

Further, the mesh interval of the wire mesh is in the range of 0.1 mm to 20 mm, and the height of the comb-shaped portion is 0.1 mm.
As described above, by setting the distance between the tip of the comb-shaped portion and the counter electrode in the range of 1 mm to 50 mm, it becomes possible to apply high power between the electrodes.

[Brief description of drawings]

FIG. 1 is a perspective view showing the concept of a plasma method gas treatment apparatus of the present invention.

FIG. 2 is an enlarged sectional view of a main part of the discharge electrode.

FIG. 3 is a perspective view showing the concept of a plasma method gas treatment apparatus.

[Explanation of symbols]

(3) Discharge electrode (5) Metal plate (6) Wire mesh (6a) Bent part (7) Comb part

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Carpenter, 3-5-28, Nishikujo 5-chome, Konohana-ku, Osaka City Nitto Shipbuilding Co., Ltd. (56) Reference JP-A-6-327963 (JP, A) JP Flat 2-131123 (JP, A) JP-A-60-110122 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01J 19/08 B01D 53/32 B01D 53/34

Claims (5)

(57) [Claims] 1. A non-equilibrium plasma (11) is generated by continuously applying a high voltage pulse between a discharge electrode (3) and a counter electrode (4), and both electrodes (3) (4) In the plasma method gas treatment device that passes the gas to be treated (8) in between to purify the exhaust gas and generate ozone using oxygen as a raw material,
A plasma characterized in that the discharge electrode (3) comprises a metal plate (5) and a wire mesh (6) supported by the metal plate and bent at both edges so as to project toward the counter electrode (4). Law gas treatment equipment. 2. The plasma method gas treatment apparatus according to claim 1, wherein a plurality of wire nets (6) are arranged in parallel. 3. The plasma method gas treatment apparatus according to claim 1, wherein the height of the comb-like portion (7) at the tip of the bent portion (6a) of the wire mesh (6) is 0.1 mm or more. . 4. The wire mesh (6) has a mesh interval of 0.1 mm.
To 20 mm, the plasma method gas treatment apparatus according to claim 1 or 2. 5. The plasma method gas treatment apparatus according to claim 1, wherein the distance between the tip of the comb-shaped portion (7) and the counter electrode (4) is in the range of 1 mm to 50 mm.