JP2006269095A - Plasma generation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma generation device capable of efficiently generating plasma under an atmospheric pressure for sterilizing and reforming gas without generating arc discharge. <P>SOLUTION: This plasma generation device having a ring-shaped or cylindrical electrode 6, a needlelike electrode 7 and a direct current high voltage source 8 applies a prescribed voltage by the direct current high voltage source 8 between the ring-shaped or cylindrical electrode 6 and the needlelike electrode 7 for generating discharge between the ring-shaped or cylindrical electrode 6 and the needlelike electrode 7 and passes working gas through a discharge position for generating plasma. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a plasma generating apparatus that generates plasma in an atmosphere of atmospheric pressure, not in a sealed vacuum environment.

  Conventionally, plasma generation has been performed in a sealed vacuum environment. For this reason, the application field of plasma will also be limited. For this reason, recently, there is an increasing demand for generating plasma in an environment of atmospheric pressure.

  According to plasma generated under an atmospheric pressure environment, for example, it is possible to sterilize or modify a gas as an object, and various applications are conceivable.

  By the way, as a method of generating plasma under an atmospheric pressure environment, it is known to use discharge. For example, Patent Document 1 discloses an example.

  In the invention described in Patent Document 1, an arc discharge is generated between a stud-shaped electrode and a casing (ground potential) covering the periphery thereof, and a working gas is blown into the discharge path, so that the working gas A technique for generating plasma is disclosed.

JP 2001-68298 A

  As in the invention described in Patent Document 1, in the conventional plasma generator, arc discharge is generated between the electrodes, and the working gas is decomposed by the heat to generate plasma.

  However, when arc discharge is used for working gas decomposition as in the prior art, a large current is required, power consumption is large, and heat decomposes the working gas to waste extra energy. However, there is a problem that a large amount of heat is generated for plasma generation, and the electrode dissolution progresses with time.

  The present invention has been made in view of the above points, and can generate plasma efficiently under atmospheric pressure without causing arc discharge, and can generate plasma that can be sterilized or reformed. An object is to provide an apparatus.

  In order to solve the above problems, the present invention includes a ring-shaped or cylindrical electrode, a needle-shaped electrode, and a high-voltage source, and the high-voltage is interposed between the ring-shaped or cylindrical electrode and the needle-shaped electrode. By applying a predetermined voltage from a source, a discharge is generated between the ring-shaped or cylindrical electrode and the needle-shaped electrode, and a working gas is passed through the discharge position to generate plasma. Plasma generator.

  Further, the present invention is characterized in that the needle-like electrode is provided at a position on a central axis of the ring-like or cylindrical electrode.

  In addition, the present invention is characterized by comprising a plurality of plasma generating apparatuses according to claim 1 or 2.

  In the invention, it is preferable that the high voltage source includes a dry battery and a high voltage generator that converts the voltage of the dry battery into a high voltage.

  The present invention is further characterized by further comprising an ion removing device for sucking unnecessary substances in the plasma working gas.

  The present invention is further characterized by further comprising an ozonolysis means for decomposing ozone in the plasma working gas.

  According to the present invention, it is possible to provide a plasma generation apparatus that can generate plasma efficiently under atmospheric pressure without generating arc discharge and can perform sterilization and reforming of gas.

  That is, according to the present invention, since arc discharge (requiring a large current) is not used for working gas decomposition as in the prior art, an effect that power consumption is small can be achieved. Further, since the working gas is not decomposed by heat, there is no extra energy wasted, no large amount of heat is generated for plasma generation, and there is no fear of electrode dissolution.

  In addition, since many high-energy electrons exist in the plasma generated by the discharge of the plasma generating apparatus of the present invention and a large amount of ozone is generated by the discharge together with the sterilization by the plasma, the sterilization by ozone can be performed at the same time. Since the sterilization action of both can sterilize more efficiently, it is very effective for sterilization of pathogenic bacteria such as SARS, and can be applied as, for example, an air cleaner in a hospital. Further, the ozone used for sterilization can be removed by ozone removing means thereafter.

  Further, according to the present invention, a large-capacity plasma with a small electric power can be generated in the atmosphere, so that it can be applied to various fields such as cleaning an object, polishing, vapor deposition and gas modification.

  In addition, according to the present invention, since discharge is used, there is no problem in post-processing, the apparatus is extremely simple, and there is an effect that the industrial value is high.

  Further, according to the present invention, it is easy to manufacture, and a device can be made with a small amount of material.

  Further, according to the present invention, plasma is generated by glow corona discharge using an unequal electric field, so that a small amount of power is sufficient.

    Further, according to the present invention, since the input voltage can be as low as about 3 V, for example, there is an effect that it can be installed anywhere such as an exhaust pipe of an automobile.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic perspective view showing a configuration of a plasma generating apparatus according to an embodiment of the present invention.

  The plasma generating apparatus 1 of the present embodiment is provided with discs 3 and 4 in a casing 2 that is a cylindrical tube, and the positions of the discs 3 and 4 in the casing 2 and the distance between the disc 3 and the disc 4 are set. It is configured to be fixed by a screw rod 5 as positioning means.

  The disc 3 is an acrylic disc, for example, which is an insulator. In the present embodiment, five through holes 3a are provided, and five ring-shaped electrodes 6 are provided so as to fit into the through holes 3a. ing.

  The disc 4 is an insulating disc, for example, an acrylic disc, like the disc 3. In the present embodiment, four through holes 4 a are provided, and five are provided at positions different from the through holes 4 a. Needle-like electrode 7 is provided.

  A DC voltage is applied between the ring electrode 6 and the needle electrode 7 by the DC power supply circuit 8. In the present embodiment, the DC power supply circuit 8 receives an AC voltage of 100 to 200 V supplied from the power plug 8a, and uses the ring electrode 6 as a cathode and the needle electrode 7 as an anode. Electric power is supplied to the electrode 7 at a DC voltage of 10 kV and a current of 0.1 mA. Although a DC voltage is applied here, the present invention is not limited to this, and any voltage such as DC, AC, or pulse may be used. This is the same in any of the following embodiments.

  The disc 4 penetrates through the hole 4a, and the disc 3 penetrates through the hole 3a. The working gas flows through the through holes 4a and 3a in the direction indicated by the arrow in FIG. 2 passes through. That is, in FIG. 1, the right side of the casing 2 is the working gas inlet, and the left side is the outlet.

  Each of the five needle-like electrodes 7 is provided to face each of the five ring-like electrodes 6, and the disc 3 is arranged so that the needle-like electrode 7 is positioned on the central axis of the ring-like electrode 6 in each combination. And the disk 4 are fixed by a screw rod 5. According to the screw rod 5, the distance between the disc 3 and the disc 4 can be adjusted. Here, the needle electrode 7 is positioned outside the ring electrode 6, but the present invention is not limited to this, and the needle electrode 7 is positioned outside the ring electrode 6. Also good. This is the same in any of the following embodiments.

  The needle electrode 7 is a needle-shaped member such as iridium alloy, tungsten or stainless steel having a diameter of 1 mm, for example, and the ring electrode 6 is a ring-shaped member such as stainless steel having an inner diameter of 8 mm and an outer diameter of 10 mm.

  The material of the casing 2 may be a metal such as SUS (stainless steel) or a resin such as acrylic as long as it is insulated from each electrode. Similarly, the screw rod 5 may be a metal such as SUS (stainless steel) or a resin such as acrylic as long as it is insulated from each electrode.

  In the present embodiment, the ring electrode 6 is grounded, and a DC voltage is applied to the needle electrode 7 by a DC power supply circuit 8 via a resistor (stable resistance, protective resistance). A glow corona discharge is generated between the electrode 6 and the electrode 6.

  When a discharge voltage is applied between the needle-like electrode 7 and the ring-like electrode 6 and a discharge is generated in this way, when a working gas is injected as shown by an arrow in FIG. Passes through the discharge path formed between the needle-like electrode 7 and the ring-like electrode 6, and the working gas is turned into plasma.

  FIG. 2 is a schematic side view showing a state of lines of electric force by one of the combinations of the five needle-like electrodes 7 and the ring-like electrode 6 shown in FIG.

  As shown in FIG. 2, according to the present embodiment, electric lines of force 9 are generated from the tip of the needle electrode 7 toward the circumference of the ring electrode 6.

  Since the electric lines of force 9 are radiated perpendicularly from the needle-like electrode 7, as shown in FIG. 2, the electric lines of force 9 are curved near the needle-like electrode 7 to form a bulge.

  In addition, the electric force lines 9 are concentrated in the vicinity of the needle-like electrode 7 and the electric field is strengthened. However, the electric force lines 9 spread toward the circumference of the ring-shaped electrode 6 and become weaker as the ring-like electrode 6 is approached. . Due to the spread of the electric force lines 9, in this embodiment, the current flowing between the needle electrode 7 and the ring electrode 6 can be reduced as much as possible, and the power consumption can be reduced.

  The working gas flowing in from the inlet of the casing 2 shown in FIG. 1 passes through the hole 4a of the disk 4 and further passes through the hole 3a of the disk 3 after passing through the electric field generated by the electric lines of force 9. Spill from. When the working gas passes through the electric field generated by the electric lines of force 9, the gas is ionized by cathode discharge. By this action, the gas can be sterilized and reformed.

  FIG. 3 shows a discharge current indicating the relationship between the applied voltage applied between the needle electrode 7 and the ring electrode 6 shown in FIG. 1 and the discharge current between the needle electrode 7 and the ring electrode 6. It is a figure of a characteristic, a horizontal axis shows an applied voltage and a vertical axis | shaft shows discharge current.

  The characteristics shown in FIG. 3 are five combinations of the needle-like electrode 7 and the ring-like electrode 6, and in each case, the distance between the needle-like electrode 7 and the ring-like electrode 6 is 10 mm, and the diameter of the needle-like electrode 7. Is 1 mm, and the diameter of the ring-shaped electrode 6 is measured with an inner diameter of 8 mm and an outer diameter of 10 mm.

  As shown in FIG. 3, the discharge starts rapidly at an applied voltage of about 8.9 kV, the current increases with the voltage, and reaches a maximum current (here, about 0.06 to 0.09 mA) at 10.9 kV. This region is glow corona discharge, and it is desirable that the plasma generator 1 of the present embodiment is driven in this region.

The power of this discharge is about 0.654 to 0.981 W, and the volume of air (mainly nitrogen) plasma as the working gas can be 1.31 cm ³ .

  Next, a second embodiment of the present invention will be described.

  FIG. 4 is a schematic sectional side view showing the configuration of the plasma generating apparatus according to the second embodiment of the present invention.

  The plasma generating apparatus 11 of the present embodiment includes a gas constricting tube 13 for directing the flow of working gas, a cylindrical electrode 14 and a rod-shaped electrode 15 in a casing 12 which is a cylindrical tube. It is prepared for.

The gas constricting pipe 13 has a conical shape with a thin tip, and the material thereof may be a resin such as acrylic or SUS (stainless steel). The gas to be introduced may include, for example, SO _X , NO _X , XO ₂ , soot, etc. in the air. According to the present embodiment, this gas can be sterilized and dissociated.

  The cylindrical electrode 14 is supported on the inner surface of the casing 12, and the rod-shaped electrode 15 is supported by a support lid 16. The support lid 16 has a hole for allowing the working gas to flow in, and has a support portion for pointing the rod-shaped electrode 15 at the center.

  The casing 12 is, for example, an acrylic tube having an outer diameter of 12 mm, an inner diameter of 10 mm, and a length of 50 mm. The rod-shaped electrode 15 is, for example, a SUS (stainless) -indium alloy rod having a diameter of 1 mm and a length of 30 mm. For example, a SUS (stainless steel) tube having an outer diameter of 10 mm, an inner diameter of 8 mm, and a length of 15 mm.

  A high voltage from the high voltage generator 17 is applied between the cylindrical electrode 14 and the rod electrode 15. The high voltage generator 17 converts, for example, a voltage from a power source 18 which is a DC 3V battery into a high voltage and supplies the voltage between the cylindrical electrode 14 and the rod electrode 15 and is constituted by, for example, an igniter or an ignition coil. The This high voltage is, for example, pulsed.

  As described above, the plasma generation apparatus 11 according to the present embodiment applies a high voltage by the high voltage generator 17 between the cylindrical electrode 14 and the rod-shaped electrode 15 and generates a glow corona discharge by an unequal electric field between the electrodes. . The working gas flowing in the direction of the arrow from the support lid 16 is turned into plasma by this discharge.

  The working gas that has flowed into the plasma generating device 11 from the support lid 16 is converged to a strong electrolysis portion near the tip of the rod-like electrode 15 by the gas constricting tube 13, and the gas is caused by this strong electric field portion. Efficiently plasmatized. As a result, for example, toxic gas can be converted to plasma and sterilized. Plasma gas is discharged from the left side of the casing 12 in FIG.

  According to this embodiment, plasma can be generated using a low voltage of a battery or the like, which can be realized with a simple power source and low power consumption.

  Next, a third embodiment of the present invention will be described. In this embodiment, a plurality of discharge tubes are provided, plasma is generated by these, and unnecessary substances such as harmful substances are removed from, for example, automobile exhaust gas by this plasma formation.

  FIG. 5 is a schematic partial cross-sectional perspective view showing the configuration of the plasma generating apparatus according to the third embodiment of the present invention.

  The plasma generation apparatus 21 according to the present embodiment includes a plurality of (five in the present embodiment) discharge tubes 24, a circular plate 23 that supports each of the discharge tubes 24, and a net-like shape in a casing 22 that is a cylindrical tube. A mesh electrode 26 having a cylindrical shape and a rod-shaped electrode 27 are provided.

  The plasma generator 21 is attached to an exhaust pipe 20 of an automobile, and removes unnecessary substances such as harmful substances of exhaust gas and discharges them.

  The circular plate 23 is an insulator, for example, an acrylic circular plate, and in the present embodiment, five through holes 23a are provided, and each of the discharge tubes 24 is supported by the through holes 4a.

  Each of the discharge tubes 24 has the same configuration as that of the plasma generation apparatus 11 shown in FIG. 4 and includes at least a rod-shaped electrode 24a and a cylindrical electrode 24b, and includes a rod-shaped electrode 24a and a cylindrical electrode 24b. When a voltage is applied between them, an electric field similar to that shown in FIG. 4 is formed.

  A high voltage from the high voltage generator 28 is applied between the rod-shaped electrode 24a and the cylindrical electrode 24b. The high voltage generator 28 converts, for example, a voltage from a power source 29, which is a DC 3V battery, into a high voltage and supplies it between the rod-shaped electrode 24a and the cylindrical electrode 24b. The high-voltage generator 28 is constituted by, for example, an igniter or an ignition coil. The

As described above, each of the discharge tubes 24 of the plasma generating apparatus 21 according to the present embodiment applies a high voltage from the high voltage generator 28 between the rod-shaped electrode 24a and the cylindrical electrode 24b, and generates an unequal electric field between the electrodes. The working gas, that is, the exhaust gas that causes glow corona discharge and flows in the direction of the arrow from the exhaust pipe 20 is converted into plasma by this discharge. This exhaust gas includes, for example, NO _X , SO _X , CO ₂ , CO, soot and the like.

  The plasma generator 21 of the present embodiment has a mesh electrode 26 and a rod electrode 27, and a high voltage is applied between the mesh electrode 26 and the rod electrode 27 by a high voltage generator 28, and plasma is applied thereto. Adsorb toxic substances in the gas. This point will be further described with reference to FIG.

  FIG. 6 is a schematic side view for explaining a state in which a harmful substance or the like is adsorbed to the mesh electrode 26 or the rod electrode 27 in the embodiment shown in FIG.

As described above, the exhaust gas flowing into the discharge tube 24 includes, for example, NO _X , SO _X , CO ₂ , CO, soot and the like. The exhaust gas is converted to plasma in the discharge tube ^{_{24, NO X +, SO X}} +, CO 2 +, CO +, C 2 +, O 2 +, positive ions 30a of the _N ^{2 +} etc. negative meshed The electrons 30b are attracted by the electrode 26, and the electrons 30b are attracted by the positive rod-shaped electrode 27, trapped by the electrodes, and the soot is charged and adsorbed by the electrodes. As a result, the gas discharged from the plasma generation device 21 is the one from which harmful substances and the like are removed.

  The ion removing device including the mesh electrode 26 and the rod electrode 27 is desirably slidable and removable for cleaning and replacement.

  Next, a fourth embodiment of the present invention will be described. This embodiment has a configuration for removing ozone in the gas to be discharged.

  FIG. 7 is a schematic sectional side view showing the configuration of the plasma generating apparatus according to the fourth embodiment of the present invention.

  The plasma generation apparatus 31 according to the present embodiment includes a cylindrical electrode 33 and a rod-shaped electrode 34 in a casing 32 that is a cylindrical tube.

  The cylindrical electrode 33 is supported on the inner surface of the casing 32, and the rod-shaped electrode 35 is supported by the support lid 35. The support lid 35 is provided with a hole for allowing the working gas to flow in, and has a support portion for pointing the rod-shaped electrode 34 at the center.

  A high voltage from the high voltage generator 39 is applied between the cylindrical electrode 33 and the rod electrode 34. The high voltage generator 39 converts, for example, a voltage from a power source 40, which is a DC 3V battery, into a high voltage and supplies the voltage between the cylindrical electrode 33 and the rod electrode 34. For example, the high voltage generator 39 includes an igniter and an ignition coil. The

  The gas that has passed through the cylindrical electrode 33 is sucked to the outside by a pump 38 provided in a pipe line of the pipe 36. Further, a sponge 37 is provided in the pipe line of the pipe 36.

  The gas converted into plasma by the discharge between the cylindrical electrode 33 and the rod-shaped electrode 34 contains ozone depending on the type of working gas, but it is desirable to remove this ozone when discharged into the outside air. . In the present embodiment, a means for decomposing ozone by the cylindrical electrode 33 and a means for decomposing ozone by the sponge 37 are provided.

  As shown in FIG. 7, the cylindrical electrode 33 preferably has b> a so that ozone is decomposed inside when the diameter (inner diameter) of the cylinder is a and the length is b. When the gas passes through the length b of the cylindrical electrode 33, ozone is decomposed.

  If ozone remains after passing through the cylindrical electrode 33, the ozone is adsorbed by the adsorbing member 37. The sponge 37 contains, for example, alkaline water having a pH of 8 or more. When the gas passes through the sponge 37, ozone is decomposed by the alkaline water.

  With the above configuration, according to the present embodiment, ozone can be removed from the exhaust gas.

It is a schematic perspective view which shows the structure of the plasma production apparatus by one embodiment of this invention. It is a schematic side view which shows the state of a line of electric force by one of the combinations of the five acicular electrodes 7 and the ring-shaped electrode 6 which were shown in FIG. FIG. 2 is a diagram of discharge current characteristics showing a relationship between an applied voltage applied between the needle electrode 7 and the ring electrode 6 shown in FIG. 1 and a discharge current between the needle electrode 7 and the ring electrode 6. is there. It is a schematic sectional side view which shows the structure of the plasma production apparatus by the 2nd Embodiment of this invention. It is a general | schematic fragmentary sectional perspective view which shows the structure of the plasma production apparatus by the 3rd Embodiment of this invention. FIG. 6 is a schematic side view for explaining a state in which a harmful substance or the like is adsorbed on the mesh electrode 26 or the rod electrode 27 in the embodiment shown in FIG. 5. It is a schematic sectional side view which shows the structure of the plasma production apparatus by the 4th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plasma generator 2 Casing 3, 4 Disc 5 Screw rod 6 Ring-shaped electrode 7 Needle-shaped electrode 8 DC power supply circuit

Claims (6)

  By having a ring-shaped or cylindrical electrode, a needle-shaped electrode, and a high-voltage source, and applying a predetermined voltage from the high-voltage source between the ring-shaped or cylindrical electrode and the needle-shaped electrode A plasma generating apparatus characterized in that a discharge is generated between the ring-shaped or cylindrical electrode and the needle-shaped electrode, and a working gas is passed through the discharge position to generate plasma.   The plasma generating apparatus according to claim 1, wherein the needle-like electrode is provided at a position on a central axis of the ring-like or cylindrical electrode.   A multi-type plasma generation apparatus comprising a plurality of the plasma generation apparatuses according to claim 1.   4. The plasma generation apparatus according to claim 1, wherein the high voltage source includes a dry battery and a high voltage generator that converts a voltage of the dry battery into a high voltage. 5.   The plasma generating apparatus according to any one of claims 1 to 4, further comprising an ion removing device that sucks an unnecessary substance in the plasma gas.   The plasma generating apparatus according to any one of claims 1 to 4, further comprising an ozonolysis means for decomposing ozone in the plasma working gas.

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