JPWO2009066395A1 - Plasma processing equipment - Google Patents

Abstract

A pair of discharge electrodes 5, 6 arranged in the vertical direction, a pair of discharge electrodes 5, 6 arranged in the axial direction of the reaction pipe so as to interpose an internal space of the reaction pipe, and a pair of discharge electrodes A power supply 13 for applying a voltage, water supply means 9 and 18 for supplying water W from the upper part of the reaction pipe, flowing along the inner wall surface of the reaction pipe, and discharging from the lower end opening 2 of the reaction pipe; A gas supply means 8 for flowing gas G into the reaction pipe and passing through the reaction pipe; electrolyte supply means 11 and 11a for supplying an electrolyte into the reaction pipe from the upper part of the reaction pipe; , Controlling the power source and the electrolyte supply means, supplying the electrolyte solution from the electrolyte supply means to form a current path between the pair of discharge electrodes, and then stopping the supply of the electrolyte solution from the electrolyte supply means The control means 14 which induces discharge by interrupting | blocking a path | route is provided. In the vicinity of the inflow portion of the gas to be treated in the reaction pipe line, a narrow passage portion 15 and an extension portion 16 following the lower portion are provided.

Description

  The present invention relates to a plasma processing apparatus for decomposing a gas to be processed using plasma generated by discharge generated between discharge electrodes.

  In the prior art, a direct current discharge plasma is generated between discharge electrodes, and a gas to be processed (a gas to be processed or a gas containing a solid or liquid component to be processed; hereinafter the same) is decomposed using the plasma. A plasma processing apparatus configured to perform a process such as detoxification is known.

  As this type of device, for example, there is one proposed by the present inventor (see Patent Document 1). The apparatus includes a reaction pipe extending downward, a pair of discharge electrodes arranged in an axial direction of the reaction pipe at intervals so that an internal space of the reaction pipe is interposed, and a pair of discharge electrodes. A power source for applying a voltage, water supply means for supplying water from the upper part of the reaction pipe, flowing along the inner wall surface of the reaction pipe, and then discharging from the lower end opening of the reaction pipe; Controls the gas supply means to be treated that flows into the passage and passes through the reaction pipe, the electrolyte supply means for supplying the electrolyte into the reaction pipe from the upper part of the reaction pipe, and the power source and the electrolyte supply means After the electrolytic solution is supplied from the electrolytic solution supply means to form a current path between the discharge electrodes, the supply of the electrolytic solution from the electrolytic solution supply means is stopped and the current path is interrupted to induce discharge. Means.

  According to this plasma processing apparatus, a discharge can be easily induced, thereby generating a plasma extending in the axial direction of the reaction pipe and converting the entire cross section of the pipe into a plasma over a long distance in the reaction pipe. By doing so, it is possible to obtain an effect that the gas to be treated can be efficiently decomposed.

  In this case, in order to further improve the decomposition efficiency of the gas to be processed, the gas to be processed is heated to a high temperature by plasma to promote the decomposition, and at the same time, water-soluble components generated by the decomposition are formed on the inner wall surface of the reaction pipe. It is necessary to dissolve quickly in the flowing water layer.

However, according to the above configuration, since the plasma formed by the discharge is located in the gas flow, its thickness changes in the axial direction, resulting in a region where the plasma is far from the flowing water layer. There was a thing. Considering this, if the diameter of the reaction pipe is reduced, the distance between the plasma and the flowing water layer is reduced, but on the other hand, there is a problem that the pipe resistance for flowing the gas to be processed increases. .
In addition, it is necessary to reduce the power consumption during the decomposition process.

JP 2004-209373 A

  Accordingly, an object of the present invention is to increase the decomposition efficiency of the gas to be processed of the plasma processing apparatus and reduce the power consumption during the decomposition process.

  In order to solve the above-described problems, the present invention provides a pair of reaction pipes that extend in the vertical direction and a pair of the reaction pipes that are spaced apart from each other in the axial direction of the reaction pipe. A discharge electrode, a power source for applying a voltage to the pair of discharge electrodes, water is supplied from the upper part of the reaction pipe, flows along the inner wall surface of the reaction pipe, and is discharged from the lower end opening of the reaction pipe And a water supply means for causing the gas to be treated to flow into the reaction pipe and passing the gas through the reaction pipe, and an inflow portion of the gas to be treated in the reaction pipe. The plasma processing apparatus is characterized in that a bottleneck part and an extended part following the bottleneck part are provided in the vicinity or at a position away from the inflow part by a predetermined distance.

In the above configuration, preferably, the bottleneck part and the extension part in the reaction pipe line are formed integrally with a wall of the reaction pipe line, or the bottleneck part and the extension part are the reaction pipe line. The wall is formed as a member separate from the wall and attached to the reaction pipe.
Preferably, the bottleneck part and the extension part are provided at a position separated from the processing gas inflow part in the reaction pipe line by a distance of ¼ to ３ of the total length of the reaction pipe line. It has been.

  Further preferably, the pair of discharge electrodes includes a high voltage electrode disposed above the reaction conduit and a ground electrode attached below the extension portion on the inner wall surface of the reaction conduit, The electrode is formed in a rod shape having a sharp tip, the tip is arranged so as to be directed into the reaction pipe in the vicinity of the upper end opening of the reaction pipe, and the ground electrode is formed in a curved plate shape. Formed and disposed along the inner wall surface of the reaction conduit, or the pair of discharge electrodes is provided with a high-pressure electrode disposed above the reaction conduit and a lower portion of the reaction conduit. The high-voltage electrode is formed in a rod shape having a pointed tip, and is arranged so that the tip is directed into the reaction pipe in the vicinity of the upper end opening of the reaction pipe. Is The ground electrode is formed in a flat plate shape, one surface is arranged adjacent to and facing the lower end opening of the reaction conduit.

  According to the present invention, in the bottleneck portion of the reaction pipe, the density of the discharge current increases, and at the same time, the high temperature portion of the plasma and the flowing water layer are close to each other. As a result, water vapor generated by the contact between the plasma and water is efficiently taken into the plasma, thereby promoting the decomposition reaction of the gas to be treated, and the water-soluble reaction products generated by the decomposition reaction are efficiently produced. Dissolved in the flowing water layer. Furthermore, by providing the extended part below the narrow part, the increase in pipe resistance is prevented and the pressure loss is reduced. Thus, according to the present invention, by providing the reaction pipe with the bottleneck part and the extension part that follows the narrow part, the decomposition efficiency of the gas to be treated is increased, and the power consumption during the treatment is reduced.

It is a longitudinal cross-sectional view which shows schematic structure of the plasma processing apparatus by one Example of this invention. It is a longitudinal cross-sectional view which shows schematic structure of the plasma processing apparatus by another Example of this invention. It is a longitudinal cross-sectional view which shows schematic structure of the plasma processing apparatus by another Example of this invention. It is a longitudinal cross-sectional view which shows schematic structure of the plasma processing apparatus by another Example of this invention. It is a longitudinal cross-sectional view which shows schematic structure of the plasma processing apparatus by another Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a Housing 1b Block 2 Through-hole 3 Pipe 4 Reaction pipe line 5, 6 Discharge electrode 7 Processed gas supply port 8 Processed gas supply pipe 9 Water supply pipe 10 Cooling water path 11 Electrolyte supply part 11a Nozzle 12 Matching circuit 13 Power supply 14 Control part 15 Kushiro part 16 Expansion part 17 Flowing water layer 18 Water reservoir 19 O-ring 20 Water tank G Processed gas W Water

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a longitudinal sectional view showing a configuration of a main part of a plasma processing apparatus according to one embodiment of the present invention. Referring to FIG. 1, a plasma processing apparatus according to the present invention includes a cylindrical housing 1a whose upper end opening is closed, and a circle that is fitted and fixed in a sealed state via an O-ring 19 at the lower end opening of the housing 1a. It has a main body composed of a columnar block 1b.
The block 1b is formed with a through hole 2 that communicates the internal space of the housing 1a with the outside of the main body along the central axis. A pipe 3 is fitted and fixed in the through hole 2 and extends upward from the block 1b into the internal space of the housing 1a. The pipe 3 forms a reaction line 4. In addition, a cooling water passage 10 is provided at the lower end of the block 1b. The cooling water passage 10 extends in the radial direction from the through hole 12 and opens to the outside.

The reaction pipe line 4 is provided with a narrow channel part 15 and an extended part 16 continuing below the narrow channel part 15 over a certain length from the upper end opening. The narrow part 15 is formed so that the inner diameter is constant over the entire length, and the expansion part 16 is formed so that the inner diameter increases at a constant rate downward from the connection position with the narrow part 15.
Further, the bottleneck portion 15 and the extension portion 16 are formed integrally with the wall of the reaction pipe line 4.

  The plasma processing apparatus according to the present invention also includes a pair of discharge electrodes 5 and 6. The pair of discharge electrodes 5, 6 includes a high voltage electrode 6 disposed above the reaction pipe 4 and a ground electrode 5 attached below the extension 16 on the inner wall surface of the reaction pipe 4.

The high-voltage electrode 6 is formed in the shape of a rod having a sharp tip, and in this case, the tip is formed from an arc-resistant material. Examples of the arc resistant material include platinum. Further, the remaining rod-like portion excluding the tip of the high-voltage electrode 6 is formed of any material that can function as a discharge electrode, such as a metal pipe, a metal rod, a carbon rod, or a Ti—Pd alloy rod. .
The high-voltage electrode 6 is attached to the center of the upper wall of the housing 1 a, extends downward from the upper wall along the central axis of the reaction pipe 4, extends into the internal space of the housing 1 a, and has a tip at the upper end opening of the reaction pipe 4. It arrange | positions so that it may oppose. In this case, the arrangement of the high voltage electrode 6 is not limited to this, and can be any arrangement in which the tip of the high voltage electrode 6 is directed into the reaction pipe line 4 in the vicinity of the upper end opening of the reaction pipe line 4, For example, an arrangement in which the tip of the high voltage electrode 6 is inserted into the reaction pipe 4 may be used.

  The ground electrode 5 is formed in a curved plate shape, and is disposed along the inner wall surface of the reaction pipe 4 and is grounded. The ground electrode 5 is preferably formed of a highly conductive metal such as brass or copper, but is not limited to these materials as long as the function of generating plasma can be exhibited.

  A power source 13 is connected to the high voltage electrode 6 via a matching circuit 12. The power source 13 is an AC high frequency power source. If the power supply 13 is a DC high-voltage power supply, the matching circuit 12 is not necessary.

  A water supply port is provided in the lower peripheral wall of the housing 1a, and the water supply tube 9 is joined to the water supply port in a sealed state. Then, water W is supplied from the water supply pipe 9 into the inner space of the housing 1a. The water W supplied into the housing 1 a is stored in a space between the inner wall surface of the housing 1 a and the outer wall surface of the reaction pipe 4, and forms a water reservoir 18 that surrounds the outside of the reaction pipe 4. Then, the water supplied beyond the capacity of the water reservoir 18 overflows from the edge of the upper end opening of the reaction pipe 4 (in this embodiment, the bottleneck portion 15), flows along the inner wall surface of the reaction pipe 4, It is discharged to the outside from the lower end opening of the block 1b.

  An opening is formed in the upper peripheral wall of the housing 1 a, and a short gas pipe is sealed and joined to the opening to provide a gas supply port 7 to be processed. A gas supply pipe 8 for supplying gas to be processed G into the housing 1a is connected to the gas supply port 7 to be processed. The gas to be processed G supplied from the gas supply pipe 8 to be processed fills the space above the water reservoir 18 in the housing 1a, and then the reaction pipe is opened from the upper end opening of the reaction pipe 4 (in this embodiment, the narrow section 15). It flows into the channel 4 and passes through the reaction tube 4.

A nozzle 11a for supplying an electrolytic solution is attached to the upper wall of the housing 1a in a sealed state. The nozzle 11a extends from the upper wall of the housing 1a into the housing 1a, and is arranged so that the tip is directed to the tip of the high-voltage electrode 6 of the discharge electrode and the upper end opening of the reaction conduit 4 (the bottleneck portion 15). The electrolyte solution supply unit 11 is connected to the rear end of the nozzle 11a that protrudes from the housing 1a. Then, the electrolytic solution is supplied from the electrolytic solution supply unit 11 into the reaction pipe line 4 through the nozzle 11a. As the electrolyte, for example, NaCl, NaOH, H ₂ SO ₄ or HNO ₃ can be used.

  Moreover, the control part 14 which controls the power supply 13 and the electrolyte solution supply part 22 is provided.

Next, the operation of the plasma processing apparatus according to the present invention will be described.
In accordance with a control signal from the control unit 14, the electrolytic solution is supplied from the electrolytic solution supply unit 11 to the nozzle 11a, and the electrolytic solution is discharged from the nozzle 11a. The electrolyte discharged from the nozzle 21 is supplied into the reaction pipe 4 directly into the reaction pipe 4 or via the high voltage electrode 6, flows along the inner wall surface of the reaction pipe 4, and flows into the ground electrode 5. Pass through.

  A high voltage is applied from the power source 13 to the high voltage electrode 6 by a control signal from the control unit 14 when a predetermined time has elapsed after the supply of the electrolyte into the reaction pipe 4 is started. At this time, a path (current path) through which a current flows between the high-voltage electrode 6 and the ground electrode 5 is formed by the electrolyte flowing on the inner wall surface of the reaction pipe 4. Current begins to flow in between. Thereafter, the supply of the electrolytic solution from the electrolytic solution supply unit 11 is stopped by the control signal from the control unit 14, and thus the supply of the electrolytic solution into the reaction pipe 4 is stopped. As a result, the current path formed in the reaction conduit 4 is interrupted, and a discharge is induced in the reaction conduit 4, thereby forming a plasma in the reaction conduit 4. In this case, the density of the discharge current increases in the bottleneck portion 15 of the reaction tube 4.

The water W supplied from the water supply pipe 9 to the water reservoir 18 overflows from the edge of the upper end opening of the reaction pipe 4 (bottle 15), flows into the reaction pipe 4, and enters the inner wall surface of the reaction pipe 4. Then, after passing through the narrow channel portion 15 and the extended portion 16, the reaction tube 4 is discharged from the lower end opening to the outside. In this way, a continuous flowing water layer 17 is formed over the entire inner wall surface of the reaction pipe line 4 including the narrow channel portion 15 and the expanded portion 16.
The gas G to be processed is supplied into the housing 1a from the gas supply pipe 8 to be processed through the gas supply port 7 to be processed. The gas to be processed G supplied into the housing 1a flows into the reaction pipe 4 and is heated to a high temperature in contact with the plasma when passing through the reaction pipe 4, and is decomposed into gas components. .

In this case, the high temperature portion of the plasma and the flowing water layer 17 are close to each other in the narrow portion 15 of the reaction pipe line 4. As a result, water vapor generated by the contact between the plasma and the water W is efficiently taken into the plasma, the decomposition reaction of the gas G to be treated is promoted, and the water-soluble reaction product generated by the decomposition reaction is efficiently discharged. Dissolved in. Furthermore, since the expansion part 16 is provided on the lower side of the bottleneck part 15, an increase in pipe resistance is prevented, and pressure loss is reduced. Moreover, since the inner wall surface of the reaction pipe line 4 is always covered with the flowing water layer 17, erosion of the inner wall surface of the reaction pipe line 4 is prevented.
Thus, according to the present invention, by providing the narrow passage 15 and the extended portion 16 that is provided below, the decomposition efficiency of the harmful substances in the gas G to be treated is increased, and further, the power consumption during the treatment is increased. Is reduced. Even a fluorine compound such as PFC containing chemically stable CF ₄ can be effectively decomposed. Further, even if the object to be processed is solid or liquid, they are mixed in an appropriate gas as a medium, supplied into the housing 1a from the gas supply port 7 to be processed, and flowed into the reaction pipe 4 Can be decomposed.

  The water-soluble reaction product generated by the decomposition is dissolved in the flowing water layer 17 formed in the reaction pipe 4 and discharged from the reaction pipe 4 together with the flowing water. In this case, by supplying water W from the cooling water passage 10 into the through-hole 2 of the block 1b, the water-soluble reaction product discharged from the reaction pipe 4 is more efficiently dissolved and removed in the water W. In addition, the exhaust side of the apparatus can be prevented from being damaged by heat.

  In the above-described embodiment, the narrow passage portion 15 and the expansion portion 16 are formed integrally with the wall of the reaction pipe line 4. However, as shown in FIG. 2, the narrow passage portion 15 ′ and the expansion portion 16 ′ are connected to the reaction pipe line 4. It may be formed as a member separate from the wall and attached to the reaction pipe 4. In this case, the narrow channel portion 15 ′ and the expanded portion 16 ′ are not necessarily made of the same material as the wall of the reaction pipe line 4, and have appropriate heat resistance and durability in consideration of exposure to running water. You only have to have it.

FIG. 3 is a longitudinal sectional view showing a schematic configuration of a plasma processing apparatus according to another embodiment of the present invention. The embodiment of FIG. 3 differs from the embodiment of FIG. 1 only in the configuration of the bottleneck portion and the extension portion in the reaction pipe. Therefore, in FIG. 3, the same components as those shown in FIG.
Referring to FIG. 3, in this embodiment, the bottleneck portion 15 ″ and the expansion portion 16 ″ are provided below the reaction pipe line from the inflow part (upper end opening of the reaction pipe line 4) of the processing gas G in the reaction pipe line 4. 4 is provided at a position that is 1/4 to 1/3 of the total length of 4. In this embodiment, the narrow channel portion 15 ″ has a first portion whose inner diameter decreases at a constant rate from the connection position with the reaction pipe line 4 toward the lower side, and an inner diameter connected to the lower side of the first portion. Is formed from a constant second portion, and the expanded portion 16 ″ is formed so that the inner diameter increases at a constant rate downward from the connecting position with the narrow portion 15 ″. Since the plasma and the flowing water layer 17 are close to each other at a position where the temperature of the generated plasma is the highest, decomposition of the gas to be treated is further promoted, and at the same time, evaporation from the flowing water layer 17 is further promoted, As a result, the gas to be processed is decomposed more efficiently, and the power consumption during processing is further reduced.

FIG. 4 is a longitudinal sectional view showing a schematic configuration of a plasma processing apparatus according to still another embodiment of the present invention. The embodiment of FIG. 4 is substantially different from the embodiment of FIG. 1 only in the configuration of the ground electrode of the discharge electrode. Therefore, in FIG. 4, the same components as those shown in FIG.
With reference to FIG. 4, in this embodiment, the reaction pipe 4 extends further downward from the block 1 b through the through hole 2 of the block 1 b, and the lower end portion of the reaction pipe 4 is stored in the water tank 20. Introduced into the water. The ground electrode 5 ′ of the discharge electrode is disposed in the water of the water tank 20 and in the vicinity of the lower end opening of the reaction pipe 4. The ground electrode 5 ′ is formed in a flat plate shape, and one surface faces the lower end opening of the reaction pipe line 4.
According to this configuration, the gas to be treated G is discharged into the water from the lower end opening of the reaction pipe 4, and is thus discharged as bubbles in the water. In this case, the discharge current that forms plasma flows to the ground electrode 5 ′ in the water tank 20. Even in such an electrode arrangement, it is possible to increase the efficiency of the decomposition treatment of the gas to be processed and reduce the power consumption during the treatment by providing the narrow channel portion 15 and the expansion portion 16 in the reaction pipe 4. This is the same as in the above embodiment.

FIG. 5 is a longitudinal sectional view showing a schematic configuration of a plasma processing apparatus according to still another embodiment of the present invention. The embodiment of FIG. 5 differs from the embodiment of FIG. 1 only in the configuration of the ground electrode of the discharge electrode. Therefore, in FIG. 5, the same components as those shown in FIG.
Referring to FIG. 5, in this embodiment, the ground electrode 5 ″ of the discharge electrode is formed in an elongated rod shape, inserted from the lower end opening side of the reaction tube 4 along the central axis of the reaction tube 4, and an appropriate In this arrangement of the discharge electrode, by providing the narrow channel portion 15 and the expansion portion 16 in the reaction pipe 4 as in the case of the above embodiment, the support electrode is used. Thus, the efficiency of the decomposition of the gas to be processed can be increased, and the power consumption during the processing can be reduced.

As a specific example, a plasma processing apparatus for decomposing CF ₄ as a gas to be processed was configured. The dimensions of each part of this device are as follows. The inner diameter of the reaction line 4 was 12 mm to 30 mm, and the length was 150 mm to 400 mm. The inner diameter of the narrow portion 15 was 8 mm to 16 mm. Further, the distance between the discharge electrodes 5 and 6 was set to 200 mm or more, preferably 250 mm or more.
By operating this plasma processing apparatus, CF ₄ could be decomposed efficiently.

Claims (6)

A reaction line extending vertically,
A pair of discharge electrodes arranged at an interval so that an internal space of the reaction conduit is interposed in the axial direction of the reaction conduit;
A power source for applying a voltage to the pair of discharge electrodes;
Water supply means for supplying water from an upper part of the reaction pipe, flowing along an inner wall surface of the reaction pipe, and discharging from a lower end opening of the reaction pipe;
A gas supply means for allowing gas to be processed to flow into the reaction pipe and passing through the reaction pipe;
A narrow passage portion and an extension portion that extends below the narrow passage portion are provided in the vicinity of the inflow portion of the gas to be treated in the reaction pipe line or at a position spaced apart from the inflow portion by a predetermined distance. Plasma processing equipment.   The plasma processing apparatus according to claim 1, wherein the bottleneck part and the extension part in the reaction pipe are formed integrally with a wall of the reaction pipe.   2. The plasma according to claim 1, wherein the bottleneck part and the extension part in the reaction pipe are formed as members separate from the walls of the reaction pipe and are attached to the reaction pipe. Processing equipment.   The said bottleneck part and the said expansion part are provided in the position away from 1/4 to 1/3 of the full length of the said reaction pipe line below the inflow part of the said process gas in the said reaction pipe line. The plasma processing apparatus according to claim 1, wherein:   The pair of discharge electrodes includes a high voltage electrode disposed above the reaction conduit and a ground electrode attached below the extension on the inner wall surface of the reaction conduit. The tip is disposed so that the tip is directed into the reaction pipe in the vicinity of the upper end opening of the reaction pipe, and the ground electrode is formed in a curved plate shape. The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus is disposed along an inner wall surface of the reaction pipe.   The pair of discharge electrodes includes a high voltage electrode disposed above the reaction conduit and a ground electrode disposed below the reaction conduit, and the high pressure electrode is formed in a rod shape having a sharp tip. In addition, the tip is arranged so as to be directed into the reaction pipe in the vicinity of the upper end opening of the reaction pipe, the ground electrode is formed in a flat plate shape, and one surface thereof is the reaction pipe. The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus is disposed so as to be close to and face a lower end opening of the path.

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