JP2008272736A - Discharge electrode and air cleaning apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air cleaning apparatus capable of stably cleaning air without generating abnormal discharge by protecting a dielectric covering the metallic conductor of a high voltage electrode from thermal stress and preventing damage. <P>SOLUTION: The air cleaning apparatus uses the discharge electrode having the high voltage electrode 2 wherein a space 2g is provided in a tube of the tubular dielectric 2b for inserting the metallic conductor 2a, and a conductor 2e electrically connecting the metallic conductor 2a to the tubular dielectric 2b, and a grounding electrode 3 with a conductor 3t connected to an adsorbent 3h adsorbing chemical substances. The space 2g between the metallic conductor 2a and tubular dielectric 2b prevents damage of the tubular dielectric body 2b by thermal stress at a discharge time. The connection of the metallic conductor 2a to the tubular dielectric 2b by the conductor 2e stabilizes the discharge and causes little abnormal discharge. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a discharge electrode used in an apparatus for decomposing and removing volatile organic compounds (hereinafter referred to as VOCs) contained in air discharged from, for example, a painting process, and an air purification apparatus using the same. It is about.

Painting factories, semiconductor factories, and printing factories use large amounts of organic solvents. VOCs discharged into the atmosphere from such factories have a significant impact on the atmospheric environment, such as the formation of hydrocarbon-based fine particles by reaction with sunlight, ozone, etc., or increasing the ozone concentration in the atmosphere. It is known. For this reason, there is a strong demand to recover and decompose VOCs.
The revised Air Pollution Control Law promulgated in 2004 requires that the emission and scattering of VOCs, which are the causative substances, be suppressed in order to prevent air pollution caused by photochemical smog and SPM (suspended particulate matter). The revised Air Pollution Control Law has made it necessary to reduce VOCs, and various methods for decomposing and removing VOCs are being studied. On the other hand, in recent years, there has been an increasing trend toward environmental improvement with respect to the working environment, and the need for reducing chemical substances such as VOCs has increased as an improvement in the working environment. As a method for removing these chemical substances such as VOCs, a method of collecting and removing the chemical substances in an adsorbent such as activated carbon has been common. However, this method saturates the adsorbent over a long period of time and lowers the purification capacity. Therefore, there is a problem in that the chemical substance is re-released from the adsorbent in which a large amount of the chemical substance is adsorbed. Therefore, it was necessary to develop a new removal method. Therefore, attention has been paid to a method using discharge plasma and an adsorbent as a purification method that can decompose chemical substances adsorbed by the adsorbent with low energy, is easy to maintain, and suppresses the re-release of the once collected chemical substances. .

  In the air purifying apparatus according to Patent Document 1, gaseous contaminants such as acetaldehyde and volatile organic compounds are purified by providing a dielectric between the electrodes that discharge VOCs and disposing a dielectric. Further, since the gap between both electrodes is covered with a dielectric, it is possible to suppress a spark discharge that becomes a problem when using discharge plasma.

Further, in the gas processing apparatus according to Patent Document 2, the air purification apparatus according to Patent Document 1 has a problem of pressure loss because the air to be processed flows in parallel with the electrodes, whereas the gas to be processed is in the dielectric member. Is disposed in the plasma processing chamber so as to flow in a direction perpendicular to the dielectric member, pressure loss is reduced. Furthermore, the contact probability between the plasma generated in the hole space of the dielectric member and the gas to be processed is increased, and the processing efficiency is increased.
JP 2003-135582 A JP 2006-187766 A

  However, in the conventional air purifying device described above, since the metal conductor is coated with the dielectric having a different coefficient of thermal expansion in the high voltage electrode, a part of the dielectric having a small coefficient of thermal expansion is damaged by the heat generated at the time of discharge. However, there is a problem that abnormal discharge may occur.

  The present invention has been made to solve the above-described problems, and even if there is a difference in thermal expansion between the metal conductor and the dielectric, the dielectric is not damaged by the heat generated during discharge, and is stable. It is an object of the present invention to provide an air purification discharge electrode capable of maintaining high processing efficiency and an air purification apparatus using the same.

  In order to solve the above-mentioned problems, a discharge electrode for purifying air according to claim 1 of the present invention has a metal conductor inserted by providing a gap in a tube of a tubular dielectric, and the metal conductor and the tubular dielectric are partially formed in the gap. A high-voltage electrode provided with a first conductor for electrically connecting the body, and a ground electrode having a second conductor connected to an adsorbent that adsorbs a chemical substance. Are opposed to each other. According to this problem solving means, the chemical substance adsorbed on the adsorbent can be decomposed by the plasma generated by the discharge of the high voltage electrode and the ground electrode. Moreover, since the space | gap is provided in the metal conductor and the tubular dielectric material, the tubular dielectric material can be prevented from being damaged by the thermal stress during discharge.

  In order to solve the above-mentioned problem, a discharge electrode for purifying air according to claim 2 of the present invention has a gap formed in a tube of a tubular dielectric, a metal conductor is inserted therein, and a metal conductor is formed in a part of the gap. A high-voltage electrode provided with a first conductor for electrically connecting a tubular dielectric, and a ground electrode having a second conductor connected to an adsorbent that adsorbs a chemical substance. It has a tube shape, and is characterized in that a high-pressure electrode is inserted with a gap provided in the tube of the adsorbent. According to this problem solving means, the chemical substance adsorbed on the adsorbent can be decomposed by the plasma generated by the discharge of the high voltage electrode and the ground electrode. Moreover, since the space | gap is provided in the metal conductor and the tubular dielectric material, the tubular dielectric material can be prevented from being damaged by the thermal stress during discharge.

  In order to solve the above-mentioned problem, a discharge electrode for air purification according to claim 3 of the present invention is provided with a metal conductor inserted into a tube of a tubular dielectric body, and a metal conductor is inserted in a part of the gap. A high-voltage electrode provided with a first conductor for electrically connecting a tubular dielectric, and a ground electrode having a second conductor connected to an adsorbent that adsorbs a chemical substance. It has a plate shape, and a high-voltage electrode is inserted in a hole formed parallel to the plate surface of the adsorbent. According to this problem solving means, the chemical substance adsorbed on the adsorbent can be decomposed by the plasma generated by the discharge of the high voltage electrode and the ground electrode. Moreover, since the space | gap is provided in the metal conductor and the tubular dielectric material, the tubular dielectric material can be prevented from being damaged by the thermal stress during discharge.

  In addition, an air purification apparatus according to the present invention includes a high-voltage power supply that supplies power to the discharge electrode, an intake fan that draws air to be treated into the discharge electrode, and a dust removal filter that removes dust from the air to be treated. It is a thing. According to this problem solving means, plasma can be generated by discharge between the high-voltage electrode and the ground electrode, and chemical substances such as VOCs adsorbed on the adsorbent of the ground electrode can be decomposed by reaction.

  According to the discharge electrode and the air purification apparatus of the present invention, since a gap is provided between the metal conductor of the high-voltage electrode and the dielectric, and the metal conductor and the dielectric are partially connected by the conductor, Even if there is a difference in thermal expansion between the metal conductor and the dielectric due to the rise in heat, the dielectric is not stressed, so the dielectric is not damaged, abnormal discharge does not occur, and stable discharge can be maintained. effective. In addition, since the ground electrode is made of an adsorbent, chemical species are removed by efficiently reacting active species such as oxygen atoms generated by discharge plasma with organic gas molecules such as VOCs concentrated in the adsorbent. There is also an effect that can be.

  Hereinafter, the configuration and operation of the discharge electrode and the air purification device according to the embodiment of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
1 is a perspective view showing a configuration of an air purification device according to Embodiment 1 of the present invention. FIG. 2 is a perspective view showing the configuration of the ground electrode portion of the discharge electrode.
As shown in FIG. 1 (a), the air purification device 1 is opposed to a plurality of high-voltage electrodes 2 in which a metal conductor 2a is inserted and provided with a gap 2g in a tubular dielectric 2b with a predetermined distance therebetween. A discharge electrode pair constituted by the ground electrode 3, a high-voltage power source 4 connected to the high-voltage electrode 2, an intake fan 5 provided behind the discharge electrode pair, and dust removal arranged in front of the discharge electrode pair The filter 6 is configured. FIG. 1B shows a cross-sectional view of the high-voltage electrode 2. A conductive film 2c is formed on the inner wall of the tubular dielectric 2b, and the gap 2g between the metal conductor 2a and the conductive film 2c is electrically connected to the metal conductor 2a and the conductive film 2c. A conductor 2e, which is one conductor, is attached. As shown in FIG. 2, the ground electrode 3 includes a plate-shaped adsorbent 3h and a strip-shaped conductor 3t that is a second conductor such as a metal attached to the peripheral side surface.

Next, the operation of the air purification apparatus according to Embodiment 1 will be described with reference to FIG.
First, to-be-treated air 7 containing VOCs is introduced into the air purifier 1 by the intake fan 5, but dust or dust floating in the air contained in the to-be-treated air 7 by the dust removal filter 6. Dust, such as particles of paint, is removed. Next, chemical substances including organic gas molecules such as VOCs contained in the air 7 to be processed that have passed through the high-voltage electrodes 2 are adsorbed by the plate-like adsorbent 3 h of the ground electrode 3. An alternating high voltage is applied to the high-voltage electrode 2 and the ground electrode 3 from the high-voltage power supply 4, and plasma is generated by silent discharge. The organic gas molecules adsorbed on the plate-shaped adsorbent 3h of the ground electrode 3 are expressed by the formula (1). To be oxidized and decomposed into carbon dioxide and water by the reaction represented by formula (6). The decomposition treatment is performed at the time of discharging with an AC high voltage applied, but the adsorption is performed at the time of discharging or not. Moreover, not only what is emitted from the adsorbent during discharge but also what is directly adsorbed into the plasma without being adsorbed is decomposed. Thereafter, the clean air 8 from which organic gas molecules have been decomposed and removed is discharged out of the air purification apparatus 1.

The main reactions involved in the decomposition of organic gas molecules of VOCs such as hydrocarbons and aldehydes contained in the air to be treated by the plasma generated by the discharge are expressed by equations (1) to (6). Specifically, the decomposition of organic gas molecules is divided into decomposition by ozone (O ₃ ) generated by discharge, decomposition by oxygen atoms (O), and decomposition by peroxide radicals (OH).
First, in the decomposition by ozone shown by the formulas (1) to (3), as shown by the formula (1), oxygen molecules (O ₂ ) are decomposed into oxygen atoms (O) by electrons (e). Next, as shown by the formula (2), ozone (O ₃ ) is generated by the oxygen atoms (O) and oxygen molecules (O ₂ ). Subsequently, as shown in Formula (3), organic gas molecules (C _k H _m O _n , where k, m, and n are integers) are converted into carbon dioxide (CO ₂ ) by this ozone (O ₃ ). Decomposed into water (H ₂ O). In the decomposition by the oxygen atom (O) represented by the formula (4), the organic gas molecule (C _k H _m O _n ) is converted into carbon dioxide (CO ₂ ) and water (H by the oxygen atom (O) represented by the formula (1). Decomposed to ₂ O). In the decomposition by the peroxide radical (OH) shown in the formula (5) and the formula (6), as shown in the formula (5), water (H ₂ O) and oxygen molecules (O ₂ ) react to react with the peroxide. Radicals (OH) are generated, and then, as shown in the formula (6), organic peroxide molecules (C _k H _m O _n ) are converted into carbon dioxide (CO ₂ ) and water (H ₂ O).
e + O ₂ → e + O + O (1)
Here, e represents an electron, and the electron is generated by discharge.
O + O ₂ → O ₃ (2)
_{C k H m O n + (} 2k + m / 2-n) O 3 → kCO 2 + (m / 2) H 2 O
+ (2k + m / 2-n) O ₂ (3)
_{C k H n O n + (} 2k + m / 2-n) O → kCO 2 + (m / 2) H 2 O (4)
H ₂ O + 1 / 2O ₂ → 2OH (5)
_{C k H m O n + (} 4k + m-2n) OH → kCO 2 + (2k + m-n) H 2 O (6)

  In a high-voltage electrode equipped with a metal conductor and a dielectric so as to cover the metal conductor, the metal conductor having a higher coefficient of thermal expansion than the dielectric expands due to the influence of heat generated during discharge, and the dielectric is brought into close contact with the metal conductor. In such a case, the dielectric may be damaged. For this reason, in this Embodiment 1, a space | gap is provided between the metal conductor 2a and the tubular dielectric 2b, and it electrically connects with the conductor 2e in one place between the metal conductor 2a and the tubular dielectric 2b. Therefore, not only can the damage of the tubular dielectric 2b due to thermal expansion be suppressed, but also abnormal discharge due to this can be suppressed. By supplying an alternating high voltage from the high voltage power source 4, a silent discharge is generated in the discharge space between the high voltage electrode 2 and the plate-like adsorbent 3h to generate plasma. By reacting active species such as oxygen atoms generated by this plasma with chemicals of organic gas molecules such as VOCs adsorbed and concentrated on the plate-like adsorbent 3h, the organic gas molecules are decomposed and removed, and plate-like adsorption is performed. The ability to adsorb and concentrate the chemical substances in the material 3h is restored. With the configuration of the first embodiment, it is possible to suppress the spark discharge from the high voltage electrode 2 and increase the power that can be supplied to the discharge electrode pair by the high voltage electrode 2 and the ground electrode 3. As a result, high generation efficiency of oxygen radicals for decomposing and removing organic gas molecules can be realized, and an air purification device with high decomposition efficiency can be realized. Further, since the damage to the tubular dielectric 2b due to thermal expansion can be suppressed, it is not necessary to cool the metal conductor 2, and it is possible to improve the decomposition efficiency by using the heat accompanying the discharge, and the air purification device can be made compact. Can be achieved.

The plate-like adsorbent 3h is made of manganese dioxide (MnO ₂ ), copper oxide (copper oxide) on a ceramic base having 16 to 155 honeycombs or corrugated cells per 1 cm ^{2 in} order to reduce pressure loss when air flows. CuO), zinc oxide (ZnO), titanium dioxide (TiO ₂ ) and their composites, and gold (Au), silver (Ag), platinum (Pt), palladium (Pd), rhodium (Ru), iridium (Ir) An adsorbent such as zeolite having a FAU structure or MFI structure made of SiO ₂ and Al ₂ O ₃ to which at least one selected catalyst is added is added. Here, FAU and MFI are structural codes determined by the International Zeolite Association (IZA). FAU is also called faujasite and has 12 members with relatively large pores with a pore diameter of about 1.2 nm. It is a ring zeolite, and its MFI structure is also called ZSM5 and has a 10-membered ring and pores with pores of 0.5 to 0.6 nm. The catalyst has the effect of promoting the oxidative decomposition reaction of organic gas molecules. Further, in order to improve the conductivity of the plate-like adsorbent 3h, manganese (Mn), copper (Cu), nickel (Ni), zinc (Zn), iron (Fe), titanium (Ti) or cobalt (Co) These metals may be added. It is desirable to add a plurality of types of the above metals in order to provide resistance to catalyst poisoning and maintain decomposition performance for a long time.

As another method for producing the plate-like adsorbent 3h, a zeolite powder and a binder (binder) such as clay or alumina that are extruded into a honeycomb or corrugated shape and then fired, and then fired, manganese dioxide (MnO ₂ ) is used as a base. A catalyst made of copper oxide (CuO), zinc oxide (ZnO), titanium dioxide (TiO ₂ ), or a composite thereof may be added by ion exchange or impregnation. In general, an adsorbent such as zeolite is porous, so it has conductivity by adsorbing moisture in the air. However, when a catalyst is attached to a hydrophobic zeolite by ion exchange, the conductivity becomes low due to low hygroscopicity, so the metal particles are mixed into the honeycomb base, or the adsorbent is attached to the metal base. Can be made conductive. Furthermore, it is possible to use metal particles having a particle size of several nanometers, or to make the metal itself have a catalytic action by making a base with a metal such as titanium, zinc, platinum, gold, or silver.

Moreover, ozone (O ₃ ) is generated as a discharge product in order to decompose and remove odor components such as organic gas molecules and NH ₃ using the discharge plasma. The amount of ozone generated is not a problem, but it is harmful when the concentration is high. Therefore, it is desirable to use an adsorbent capable of decomposing ozone for the plate-like adsorbent 3h, and an ozone decomposition catalyst such as activated carbon is added. Then, ozone leaking out from the air purification device 1 can be reduced. Furthermore, when an ozone decomposing catalyst such as manganese dioxide, iron, copper, or nickel is used, ozone can be decomposed into oxygen molecules (O ₂ ) and oxygen atoms (O) having higher oxidizing power than ozone. Since the generated oxygen atoms remain on the ozone decomposition catalyst, there is an effect that the oxygen atoms can be decomposed by contact reaction with organic gas molecules adsorbed on the ozone decomposition catalyst.

  The metal conductor 2a is made of, for example, stainless steel, iron, copper, or tungsten, and may have any shape such as a plate, a rod, or a wire, but the outer shape of the high-voltage electrode 2 is the same as that of the ground electrode 3. The rod-like shape is preferable because the air to be treated reaches the entire surface of the plate-shaped adsorbent 3h uniformly and discharges uniformly over the entire surface of the plate-shaped adsorbent 3h. As an example, the dimensions of the high voltage electrode 2 are as follows: the diameter of the metal conductor 2a is 1 mmφ, the outer diameter of the tubular dielectric 2b is 3 mmφ, the wall thickness is 0.5 mm, the film thickness of the conductive film 2c is 0.3 mm, and the gap is 2g. Is 0.2 mm, and the overall length is 100 mm. Examples of the material of the tubular dielectric 2b include quartz, glass, zirconia, alumina, mullite, and steatite ceramic. However, any dielectric that has high withstand voltage, heat resistance, high dielectric constant, and low dielectric loss may be used. However, it is not limited to these. Moreover, when the shape of the metal conductor 2a is a columnar shape, the tubular dielectric 2b covering the metal conductor 2a preferably has a cylindrical shape.

  The thinner the tubular dielectric 2b is, the smaller the discharge start voltage can be. However, the strength decreases and the possibility of damage increases. In addition, when the thickness of the tubular dielectric 2b is increased, the applied voltage is increased, which can be a factor that hinders permeation of the air to be treated. Therefore, it is desirable to use 0.5 to 1 mm as the thickness of the tubular dielectric 2b. . By using a dielectric having a thickness in this range, discharge plasma can be generated at a low discharge start voltage, and damage to the dielectric can be suppressed. Further, if the discharge gap length between the high-voltage electrode 2 and the plate-shaped adsorbent 3h is less than 1 mm, the air 7 to be treated does not reach the surface of the plate-shaped adsorbent 3h behind the high-voltage electrode 2 and the pressure loss increases. It leads to. When the discharge gap length is 5 mm or more, the voltage required for starting the discharge increases, so the load of the high-voltage power supply 4 increases. For this reason, the discharge gap length is desirably about 1 to 5 mm.

  The distance of the gap 2g between the metal conductor 2a and the tubular dielectric 2b is determined by the volume expansion coefficient of the metal conductor 2a and the tubular dielectric 2b. For example, SUS304 is used for the metal conductor 2a and alumina ceramic is used for the dielectric 3. In the case where the temperature rise accompanying the discharge is 150 ° C., the volume expansion coefficient of SUS304 is 0.0078, whereas the volume expansion coefficient of alumina ceramic is 0.0036. Damage to the tubular dielectric can be suppressed by providing a distance of 1.5% or more with respect to the volume of the metal conductor 2a.

  Here, the conductor 2e that contacts and connects between the metal conductor 2a and the tubular dielectric 2b may be any material having conductivity, for example, a metal spring other than filling with a substance having conductivity. A metal mesh or the like may be used. When the metal conductor 2a expands during discharge by electrically connecting the metal conductor 2a and the dielectric 2b, the metal spring or the metal mesh contracts. Thus, the stress applied to the dielectric 2b can be reduced, so that damage to the tubular dielectric 2b can be suppressed. The conductor 2e to be contact-connected is preferably at one place in consideration of the stress of the tubular dielectric 2b due to the expansion of the metal conductor 2a.

  In addition, as a method of forming the conductive film 2c on the inner wall of the tubular dielectric 2b, there are a method of plating, coating, pasting, sputtering, and the like. With this conductive film 2c, abnormal discharge in the gap 2g between the metal conductor 2a and the tubular dielectric 2b can be suppressed, and occurrence of damage to the tubular dielectric 2b due to expansion of the metal conductor 2a caused by heat generation during discharge can be suppressed.

  In order to decompose organic gas molecules such as VOCs adsorbed on the plate-shaped adsorbent 3h of the ground electrode 3 and odorous substances such as ammonia, a peak value generated by the high voltage power source 4 is 1 to 30 kV, and a frequency is 50 to 10,000 Hz. Between the high-voltage electrode 2 and the plate-like adsorbent 3h of the ground electrode 3 by applying a positive sine wave or rectangular wave AC high voltage, or positive and negative bipolar or positive or negative unipolar voltage Can be discharged. The applied voltage and frequency to be discharged are determined by the distance between the high-voltage electrode 2 and the ground electrode 3 and the input energy necessary for decomposing the adsorbed organic gas molecules. Due to the presence of the tubular dielectric 2b between the metal conductor 2a and the plate-like adsorbent 3h, when the discharge is started, charge transfer occurs on the surface of the tubular dielectric 2b, and the high voltage electrode 2 surface is uniformly discharged. Can be generated. Further, the presence of the tubular dielectric 2b suppresses a short circuit between the metal conductor 2a and the plate-like adsorbent 3h.

  FIG. 3 shows an example of the relationship between the volume resistivity of the plate-like adsorbent and the discharge power with respect to the input power. Here, the power supply frequency is 1 kHz, the discharge gap length between the high-voltage electrode 2 and the plate-like adsorbent 3 h is 2 mm, and the moisture content of the air to be treated is 13,000 ppm (dew point temperature: 11 ° C.). When the volume resistivity of the plate-like adsorbent 3h is 8.5 MΩm, the discharge power when an AC high voltage of 12 kV is applied is 58 W, whereas when the volume resistivity is 15 MΩm, the same 12 kV Even when an alternating high voltage is applied, it is 33 W, and the discharge power for the same applied voltage tends to decrease as the volume resistivity increases. From this figure, it is understood that when the discharge plasma is generated, it becomes difficult for the discharge current to flow as the electric resistance of the plate-like adsorbent 3h of the ground electrode 3 increases, and the discharge power becomes lower than the input power. Therefore, when the decomposition treatment is performed with the discharge plasma under these conditions, it is desirable to use a plate-like adsorbent 3h having a volume resistivity of 8.5 MΩm or less.

FIG. 4 is a diagram showing a power feeding method for applying a high voltage from the high voltage power source 4 to the high voltage electrode 2. FIG. 4A shows a method in which a plurality of high-voltage electrodes 2 are fixed and supplied with metal leaf springs 9. FIG. 4B shows a method of supplying power by connecting with the linear power supply 10. In addition, a plate-type power supply (not shown) can be used instead of the linear shape. In particular, since the high voltage electrode 2 can be fixed by using the leaf spring power supply 9, uniform discharge plasma can be realized for the plate-like adsorbent 3h.
Since a high voltage is applied to the high-voltage electrode 2, if the discharge gap length between the plate-shaped adsorbent 3h facing the high-voltage electrode 2 is non-uniform, the electric field concentrates at one point, and there is a high possibility of progressing to spark discharge. Therefore, the discharge plasma is not generated uniformly. As a result, the adsorbent is regenerated only locally, and the chemical substance concentrated in the plate-like adsorbent 3h cannot be completely decomposed and removed. Therefore, FIG. 5 shows a perspective view of an example in which the distance between the high-voltage electrode 2 and the ground electrode 3 is kept constant and fixed. The insulating support 11 is provided with a recess 11s and the high voltage electrode 2 is fixed to maintain a uniform discharge gap length with the plate-like adsorbent 3h. By connecting to the power supply 4, the plurality of high voltage electrodes 2 can be adjusted to the same potential. Further, by embedding the leaf spring supply electron 9 in the recess 11s of the insulating support 11, an abnormal discharge from the leaf spring supply electron 9 to the plate-like adsorbent 3h can be prevented. The metal conductor 2 a of the high-voltage electrode 2 is connected by a leaf spring power supply 9 and connected to the high-voltage power supply 4. On the other hand, the ground electrode 3 is grounded by a strip-shaped conductor 3t attached around the side surface of the plate-like adsorbent 3h.

  As the material of the support member 11, since it is necessary to suppress the occurrence of abnormal discharge between the metal conductor 2e and the plate-like adsorbent 3h, a material having high insulation is desirable. For example, insulating materials such as polyethylene, vinyl chloride, natural rubber, porcelain, glass, synthetic resins such as polyester, epoxy, melamine, phenol, and polyurethane, and inorganic materials such as mica, asbestos, and glass fiber are desirable. Furthermore, since it generates heat by discharge plasma, a material excellent in heat resistance is preferable. Further, since the discharge gap length between the high-voltage electrode 2 and the plate-like adsorbent 3h is kept constant by the support material 11, a uniform discharge plasma can be generated at the interface with the plate-like adsorbent 3h, and the plate-like adsorption The material 3h can be completely regenerated.

  FIG. 6 shows a cross-sectional view of the discharge electrode pair when the conductive film is not formed on the inner wall of the tubular dielectric 2b. The conductor 2e is provided in the gap between the metal conductor 2a and the tubular dielectric 2b along the length direction of the tubular dielectric 2b, and the metal conductor 2a and the tubular are formed at one position with respect to the radial direction of the tubular dielectric 2b. The dielectric 2b is connected. The conductor 2e is provided on the inner wall side of the tubular dielectric 2b on the side facing the plate-like adsorbent 3h, considering that plasma is generated by discharge between the high-voltage electrode 2 and the ground electrode 3 due to discharge. desirable.

  When the creepage distance of the support material 11 is not sufficient, creeping discharge progresses and no discharge plasma is generated in the space between the high-voltage electrode 2 and the plate-like adsorbent 3h. The voltage value applied to the high-voltage electrode 2 is determined by the material of the support material 11 and the like, but when the creepage distance S and the discharge gap length D are the same distance, the voltage is supported between the high-voltage electrode 2 and the plate-like adsorbent 3h. There is a possibility that creeping discharge progresses along the material, and discharge plasma cannot be generated. Here, as shown in FIG. 6, the taper portion 12 having the angle θ is provided in the support material 11 so that the opening on the plate-like adsorbent 3 h side becomes large so that the creepage distance S becomes longer than the discharge gap length D. The creeping distance S can be made longer than the discharge gap length D if the angle θ is less than 90 degrees. Preferably, by setting the angle θ in the range of 15 to 45 degrees, the creeping distance S is increased, and creeping discharge between the high-voltage electrode 2 and the plate-like adsorbent 3h can be suppressed. Furthermore, by providing the angle θ, the effective adsorption area of the plate-like adsorbent 3h is increased, and the pressure loss with respect to the air to be treated 7 can be reduced. Further, by forming irregularities on the side surface of the support material 11, the same effect can be obtained even if the creeping distance is increased.

  As described above, according to the air purification device of the first embodiment, the gap 2g is provided between the metal conductor 2a of the high-voltage electrode 2 and the tubular dielectric 2b, and the conductor 2e is used to connect the metal conductor 2a and the tubular dielectric 2b. Since the inner wall is contact-connected by the conductor 2e, the tubular dielectric 2b is not affected by the thermal expansion of the metal conductor 2a due to discharge, and the damage to the tubular dielectric 2b is reduced and abnormal discharge does not occur. There is an effect that the discharge decomposition treatment of the organic gas molecules adsorbed on the plate-like adsorbent 3h of the ground electrode 3 can be performed. In addition, since the conductive film 2c is formed on the inner wall of the tubular dielectric 2b, the surface of the high voltage electrode 2 can be uniformly discharged, and there is an effect that stable discharge can be achieved.

Embodiment 2. FIG.
FIG. 7 is a perspective view and a cross-sectional view of the discharge electrode pair showing the configuration of the air purification apparatus according to Embodiment 2 of the present invention.
7A and 7B, the gap 13g is provided in the cylindrical adsorbent 13h of the ground electrode 13, the high-voltage electrode 2 is inserted and installed concentrically, and the strip conductor 13t is attached to the cylindrical adsorbent 13h. Except for this point, it is the same as that of FIG.

Next, the operation of the air purification apparatus according to Embodiment 2 will be described with reference to FIG.
First, to-be-treated air 7 containing VOCs is introduced into the air purifier 1 by the intake fan 5, but dust or dust floating in the air contained in the to-be-treated air 7 by the dust removal filter 6. Dust, such as particles of paint, is removed. Next, chemical substances including organic gas molecules such as VOCs contained in the air to be treated 7 are adsorbed by the cylindrical adsorbent 13 h of the ground electrode 13. A high voltage is applied to the high-voltage electrode 2 and the ground electrode 13 from the high-voltage power supply 4, and plasma is generated by discharge, and the organic gas molecules adsorbed on the cylindrical adsorbent 13 h of the ground electrode 13 are oxidized, and carbon dioxide and Decomposed into water. Thereafter, the clean air 8 from which organic gas molecules have been decomposed and removed is discharged out of the air purification apparatus 1.

  As described above, according to the air purification device according to the second embodiment, since the conductor 2e is contact-connected between the metal conductor 2a and the inner wall of the tubular dielectric 2b, the tubular dielectric 2b is a metal associated with discharge. The discharge decomposition treatment of organic gas molecules adsorbed on the cylindrical adsorbent 13h of the ground electrode 3 can be performed without being affected by the thermal expansion of the conductor 2a, reducing damage to the tubular dielectric 2b, and causing no abnormal discharge. The high-voltage electrode 2 has the same effect as that of the first embodiment, and the gap 13g is provided in the cylindrical adsorbent 13h so as to be inserted. Therefore, the discharge electrodes of the high-voltage electrode 2 and the ground electrode 13 are provided. Since the discharge distance of the pair can be adjusted independently, the distance can be easily adjusted, the accuracy is improved, and the discharge is stabilized.

Embodiment 3 FIG.
FIG. 8 is a transparent perspective view showing the configuration of the air purifying apparatus according to Embodiment 3 of the present invention.
In FIG. 8, except that the gap 14g is provided in the plate-like adsorbent 14h of the ground electrode 14, the high-voltage electrode 2 is inserted and installed concentrically, and the strip-like conductor 14t is attached to the plate-like adsorbent 14h. Since it is the same as that of FIG. 1 of Embodiment 1, description of another code | symbol is abbreviate | omitted.

Next, the operation of the air purification apparatus according to Embodiment 3 will be described with reference to FIG.
First, to-be-treated air 7 containing VOCs is introduced into the air purifier 1 by the intake fan 5, but dust or dust floating in the air contained in the to-be-treated air 7 by the dust removal filter 6. Dust, such as particles of paint, is removed. Next, chemical substances including organic gas molecules such as VOCs contained in the air to be treated 7 are adsorbed by the plate-like adsorbent 14 h of the ground electrode 14. A high voltage is applied to the high-voltage electrode 2 and the ground electrode 14 from the high-voltage power supply 4, and plasma is generated by discharge, and the organic gas molecules adsorbed on the plate-like adsorbent 14 h of the ground electrode 14 are oxidized, and carbon dioxide and Decomposed into water. Thereafter, the clean air 8 from which organic gas molecules have been decomposed and removed is discharged out of the air purification apparatus 1.

  As described above, according to the air purification device according to the third embodiment, since the conductor 2e is contact-connected between the metal conductor 2 and the inner wall of the tubular dielectric 2b, the tubular dielectric 2b is a metal accompanying discharge. The discharge decomposition treatment of organic gas molecules adsorbed on the plate-shaped adsorbent 14h of the ground electrode 14 can be performed without being affected by the thermal expansion of the conductor 2a, reducing damage to the tubular dielectric 2b, and causing no abnormal discharge. The high-voltage electrode 2 is provided with a gap 14g in the plate-like adsorbing material 14h and inserted and disposed, so that the discharge electrodes of the high-voltage electrode 2 and the ground electrode 14 are provided. Since the discharge distance of the pair can be adjusted independently, there is an effect that the distance can be easily adjusted. Further, since the adsorbent is plate-shaped, there is an effect that the treatment can be performed efficiently without reducing the contact area between the air to be treated and the adsorbent.

Embodiment 4 FIG.
FIG. 9 is a perspective view showing an air purifying apparatus according to Embodiment 4 of the present invention.
9 is the same as FIG. 1 of Embodiment 1 except that a variable induction load L is installed in series between the high-voltage electrode 2 and the high-voltage power supply 4, and therefore other reference numerals are explained. Omitted.

  Next, the operation of the air purification apparatus according to Embodiment 4 will be described with reference to FIG. Capacitance C1 exists in the tubular dielectric 2b of the high-voltage electrode 2, and capacitance C2 exists in the discharge gap between the tubular dielectric 2b and the plate-like adsorbent 3h (not shown). When an AC high voltage is applied from the high-voltage power supply 4, the phase of the applied voltage waveform and the discharge current waveform shifts, and the power efficiency with respect to the applied voltage decreases. By providing the variable inductive load L, the phase shift can be eliminated and the power efficiency can be improved. The required additional dielectric load value is the combined capacitance C (= (C1 + C2) / C1 · C2) of the capacitance C1 of the tubular dielectric 2b and the capacitance C2 of the discharge gap, and the value of the power supply frequency f of the high-voltage power supply 4. However, for example, when the power supply frequency is 1 kHz and the combined capacitance C of the capacitance of the tubular dielectric 2b and the additional capacitance of the discharge gap length is 40 pF, an example of the relationship between the additional inductive load value and the power efficiency is illustrated. 10 shows. In this example, in order to increase the power efficiency to 80% or more, it is desirable to set the inductive load value to 620 to 650H. In the case of a dielectric load value outside this range, the input power with respect to the applied voltage decreases. In order to input the necessary power, it is necessary to increase the applied voltage. When the applied voltage is increased, there is a possibility that abnormal discharge from the high-voltage electrode 2 to the housing of the air purification device 1 is induced. By setting within the range of the inductive load described above, the phase shift between the applied voltage waveform and the discharge current waveform can be eliminated, and the power efficiency of the high-voltage power supply can be improved. Moreover, the variable induction load L may be installed in parallel with the high voltage electrode 2, and both the series and the parallel may be provided.

  As described above, according to the air purification device of the fifth embodiment, the variable dielectric load L is installed in series or in parallel with the high-voltage electrode 2 or both, so that the capacitance of the tubular dielectric 2b can be increased. Optimum additional inductive load value that adds a phase shift between the applied high voltage AC voltage applied from the high voltage power supply 4 and the discharge current waveform due to the capacitance of the discharge gap between the high voltage electrode 2 and the plate-like adsorbent 3h. This has the effect of being able to be eliminated by improving the power efficiency of the high-voltage power supply 4. Further, since the applied voltage can be optimized and kept low, it has an effect of suppressing abnormal discharge.

Embodiment 5. FIG.
FIG. 11 is a perspective view showing an air purifying apparatus according to Embodiment 5 of the present invention.
In FIG. 11, except that a variable resistor R1 for adjusting the conductivity of the plate-like adsorbent 3h is provided in series between the ground electrode 3 and the earth, Since it is the same, description of another code | symbol is abbreviate | omitted.

  Next, the operation of the air purification apparatus according to Embodiment 5 will be described. The ground electrode is made of an adsorbent, but when the adsorbent adsorbs moisture contained in the air to be treated, the conductivity changes and the electric resistance value of the adsorbent changes. As an example, when the power supply frequency is 1 kHz, the discharge gap length between the high-voltage electrode 2 and the plate-like adsorbent 3h is 2 mm, the moisture concentration contained in the air to be treated is 1,800 ppm (dew point temperature: −20 ° C.), 6 FIG. 12 shows the relationship between the applied voltage and the discharge power at 3,000 ppm (0 ° C.) and 13,000 ppm (11 ° C.). It can be seen that the discharge power with respect to the applied voltage from the high-voltage power supply 4 varies depending on the moisture concentration. Since environmental conditions such as season and weather are different, it is difficult to maintain the electric resistance value of the plate-like adsorbent 3h of the ground electrode 3 at a constant value, and therefore it is adsorbed in series or in parallel to the high-voltage electrode 2. By connecting a variable resistor R1 for adjusting the electrical conductivity of the material, the impedance of the discharge electrode pair can be maintained at a constant value and can be maintained at a constant processing efficiency. When the value of the variable resistor R1 is several GΩ or more, power loss in the variable resistor R1 increases. Therefore, it is desirable to set the resistance value to several MΩ or less. In the above description, the variable resistor R1 is installed in series with the ground electrode. However, the variable resistor R1 may be installed in parallel with the ground electrode.

  As described above, according to the air purifying apparatus according to the fifth embodiment, by installing the variable resistor R1 in series between the ground electrode 3 and the ground, moisture is adsorbed on the plate-like adsorbent 3h, and the electric resistance value. Even if is changed, by adjusting the resistance value, there is an effect that the impedance of the discharge electrode pair can be maintained at a constant value and can be maintained at a constant processing efficiency.

Embodiment 6 FIG.
FIG. 13 is a transparent perspective view showing an air purification device according to Embodiment 6 of the present invention.
13 is the same as FIG. 1 of the first embodiment except that a variable resistor R2 for suppressing arc discharge is installed in series between the high voltage electrode 2 and the high voltage power source 4, Explanation of the reference numerals is omitted.

Next, the operation of the air purification device according to Embodiment 6 will be described. Usually, an alternating high voltage is applied to the high-voltage electrode 2 from the high-voltage power source 4 to generate a silent discharge to decompose organic gas molecules such as VOCs contained in the air 7 to be treated. However, the electrical conductivity of the discharge space increases due to factors such as the environmental atmosphere, and there is a possibility of progressing from silent discharge to arc discharge between the high-voltage electrode 2 and the ground electrode 3. Furthermore, depending on the thickness of the tubular dielectric 2b, progress to spark discharge can be considered. Therefore, by installing a variable resistor R2 for suppressing arc discharge in series with the high-voltage electrode 2 and adjusting the resistance value, Discharge can be suppressed and a constant processing efficiency can be maintained. Here, the value of the variable resistor R2 for arc discharge suppression, as long as it has a resistance value capable of suppressing the discharge current during a short circuit to less than 1mA, the resistance value [maximum applied voltage / 10 ^{- 3} ] It is desirable that it be Ω or more.

  As described above, according to the air purifying apparatus according to the sixth embodiment, the variable resistor R2 is installed in series between the high-voltage electrode 2 and the high-voltage power supply 4, and the resistance value is adjusted by changing the conductivity of the discharge space. By doing so, there is an effect that it is possible to suppress the silent discharge from progressing to the arc discharge and to maintain a constant processing efficiency.

In the above-described embodiment, the case where zeolite is used as the adsorbent has been described, but the same effect can be expected even when silicalite having SiO ₂ having the same MFI structure as a main component is used.

  Moreover, in the figure, the same code | symbol shows the same or an equivalent part.

1 is a perspective view and a cross-sectional view showing a configuration of an air purification device according to Embodiment 1. FIG. 2 is a schematic perspective view showing a ground electrode of the air purification device according to Embodiment 1. FIG. It is a schematic perspective view which shows the relationship between the volume resistivity of the plate-shaped adsorbent with respect to the input electric power in the air purification apparatus which concerns on Embodiment 1, and discharge electric power. It is a perspective view which shows the electric power feeding method to the high voltage | pressure electrode of the air purification apparatus which concerns on Embodiment 1. FIG. It is a perspective view which shows the structure of the discharge electrode pair of the air purification apparatus which concerns on Embodiment 1. FIG. It is sectional drawing of the discharge electrode pair for demonstrating operation | movement of the air purification apparatus which concerns on Embodiment 1. FIG. FIG. 6 is a perspective view and a cross-sectional view showing a configuration of an air purification device according to Embodiment 2. FIG. 6 is a perspective view showing a configuration of an air purification device according to Embodiment 3. FIG. 6 is a perspective view illustrating a configuration of an air purification device according to a fourth embodiment. It is a figure which shows the relationship between the additional induction load value in the air purification apparatus which concerns on Embodiment 4, and power efficiency. FIG. 9 is a perspective view showing a configuration of an air purification device according to a fifth embodiment. It is a figure which shows the relationship between the applied voltage with respect to the moisture concentration in the air purification apparatus which concerns on Embodiment 5, and discharge electric power. FIG. 10 is a perspective view illustrating a configuration of an air purification device according to a sixth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air purification apparatus 2 High voltage electrode 2a Metal conductor 2b Tubular dielectric 2c Conductive film 2d Air gap 2e Conductor 3 Ground electrode 3h, 14h Plate-shaped adsorbent 3t, 13h, 14h Strip conductor 4 High voltage power supply 5 Fan 6 Dust removal filter 13h Cylinder Adsorbent L Variable induction load R1, R2 Variable resistance

Claims (10)

A high-voltage electrode provided with a first conductor that electrically connects the metal conductor and the tubular dielectric in a part of the gap, with a gap provided in a tube of the tubular dielectric, a metal conductor inserted;
A ground electrode having a second conductor connected to an adsorbent that adsorbs a chemical substance;
With
A discharge electrode for purifying air, wherein the high-voltage electrode and the ground electrode are opposed to each other. A high-voltage electrode provided with a first conductor that electrically connects the metal conductor and the tubular dielectric in a part of the gap, with a gap provided in a tube of the tubular dielectric, a metal conductor inserted;
A ground electrode having a second conductor connected to an adsorbent that adsorbs a chemical substance;
With
The discharge electrode for air purification | cleaning characterized by the said adsorbent being a pipe | tube shape, providing the space | gap in the pipe | tube of the said adsorbent, and inserting the said high voltage | pressure electrode. A high-voltage electrode provided with a first conductor that electrically connects the metal conductor and the tubular dielectric in a part of the gap, with a gap provided in a tube of the tubular dielectric, a metal conductor inserted;
A ground electrode having a second conductor connected to an adsorbent that adsorbs a chemical substance;
With
A discharge electrode for air purification, wherein the adsorbent has a plate shape, and the high voltage electrode is inserted in a hole formed in parallel to the plate surface of the adsorbent.   The discharge electrode for air purification | cleaning in any one of Claims 1-3 in which the electrically conductive film is formed in the inner wall of a tubular dielectric material.   The discharge electrode for air purification according to any one of claims 1 to 3, wherein the adsorbent is a material in which zeolite is attached to a base as an adsorbent.   Manganese, copper, nickel, zinc, iron, titanium, cobalt oxides and composites thereof, and at least one catalyst selected from gold, silver, platinum, palladium, rhodium, and iridium are added to the adsorbent. The discharge electrode for air purification | cleaning of Claim 5 characterized by the above-mentioned.   A high-voltage power supply that supplies power to the discharge electrode according to any one of claims 1 to 6, a fan for intake air that draws air to be treated into the discharge electrode, and a dust removal filter that removes dust from the air to be treated And an air purification device.   8. The air purifier according to claim 7, further comprising a variable induction load in series or in parallel with the high voltage electrode.   The air purifier according to claim 7, further comprising a variable resistor in series with the high voltage electrode.   The air purifier according to claim 7, further comprising a variable resistor in series with the ground electrode.

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