JP2007045671A - Panel-shaped discharge cell for ozone generation unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate an ozone gas of high cleanliness by avoiding the pollution of the gas from a discharge cell in a panel-shaped discharge cell for an ozone generation unit. <P>SOLUTION: A laminate block is structured by connecting a plurarity of panels 10, 20, 30 and 40 comprising a sintered compact of high purity ceramic bonded by a glass binder 50. A closed void (discharge void 70) for discharge is formed between neighboring two panels 10 and 10 among the plurarity of panels. A first gas flow route 80 for introducing a feed gas to the discharge void 70 and a second gas flow route 80 to discharge ozone gas from the discharge void 70 are formed in the layered direction of the laminate communicated with the discharge void 70. Electrode layers 15, 15 are located on the back side of the panels 10, 10 for discharge in the discharge void 70, they are sealed between the panels 10 and 20 so as not to interfere with the above-mentioned gas flow routes 80, 80. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a discharge cell used in an ozone generator, and more particularly to a plate-type discharge cell using a plate-like dielectric.

  The discharge cells used in the ozone generator are roughly classified into a plate type and a tube type, and the plate type is further subdivided into a disc type and a square plate type. Plate-type discharge cells are frequently used to generate high-concentration ozone because the discharge gap between a pair of dielectric plates is easily narrowed and the discharge gap dimensions are easily equalized. A typical structure of the plate discharge cell will be described below.

  A dielectric plate made of a square ceramic plate or the like is disposed opposite to each other with a predetermined gap, and a discharge gap is formed therebetween. The pair of dielectric plates have electrode layers coated on the respective surfaces on the back side. A predetermined high-frequency high voltage is applied between the electrode layers provided on each back side in order to generate discharge in a gap (discharge gap) between the pair of dielectric plates. In this state, a source gas such as oxygen gas is circulated in the discharge gap between the dielectric plates. Thereby, the source gas is ozonized.

  Usually, the discharge gap is forcibly cooled from the back side of the pair of dielectric plates. In order to form the cooling part on the back side of the pair of dielectric plates, a ceramic plate similar to the dielectric plate is laminated on the back side. That is, one of the typical structures of the plate-type discharge cell is a ceramic laminated structure in which ceramic plates are laminated, and one of them is the ceramic block structure described in Patent Document 1.

JP-A-11-268902

  In the discharge cell described in Patent Document 1, a plurality of substantially square ceramic plates are laminated in the plate thickness direction. More specifically, green sheets, which are ceramic plates before sintering, are laminated and sintered to be integrated into a ceramic block. The two ceramic plates in the middle are dielectric plates, and a spacer for forming a discharge gap is sandwiched between them.

  Each ceramic plate has a horizontally long gas flow through hole along two side edges of the parallel plate, and a horizontally long refrigerant along the side edge of the other two parallel side edges. It has a through hole for circulation. One set of gas circulation through holes are combined in the stacking direction to form a pair of horizontally long and vertically oriented gas flow paths, and one set of refrigerant flow through holes are combined in the stacking direction to be horizontally long and vertically long. A set of refrigerant channels is formed. The electrode layer is formed in a quadrangular region surrounded by the gas circulation through hole and the refrigerant circulation through hole.

  During operation, the source gas is introduced into one of the set of vertically oriented gas flow paths. The source gas flows through the discharge gap formed between the two dielectric plates in a direction parallel to the dielectric plate, and is ozonized during this time and is discharged from the other vertical gas flow path. Cooling water is used as the refrigerant, and this is introduced into one of the set of vertically oriented refrigerant flow paths. The cooling water flows along the dielectric plate on the back side of the pair of dielectric plates to remove heat, and is discharged from the other vertically oriented refrigerant flow path.

  In the discharge cell having a ceramic block structure described in Patent Document 1, since a block structure in which a plurality of ceramic plates are integrated by sintering is employed, both the cells and the individual plate materials are extremely high in rigidity. . Nevertheless, there is a problem that the in-plane uniformity of the discharge gap amount due to the deformation of the dielectric plate and the ozone generation efficiency due to this decrease. This is because deformation of the ceramic plate (green sheet) is inevitable during the sintering process of the ceramic plate.

  In addition to this, this discharge cell has an essential problem that it is not suitable for producing high-purity clean ozone gas. This is because if the purity of the ceramic plate is increased to prevent ozone gas contamination, integration by sintering becomes difficult.

  An object of the present invention is to provide a plate-type discharge cell for an ozone generator that has a highly rigid block structure, is suitable for generating clean ozone gas, and has high in-plane uniformity of the discharge gap amount.

  In order to achieve the above object, a plate discharge cell for an ozone generator according to the present invention is a laminate formed by joining a plurality of plate materials made of a sintered body of high-purity ceramics using a nonmetallic inorganic bonding material. A closed block for discharging is formed between two adjacent plates of the plurality of plates, and the first gas flow path for introducing the source gas into the closed gap and the closed A second gas flow path for deriving ozone gas from the gap is formed in communication with the closed space in the stacking direction in the stack, and each of the two plate members for discharging in the closed gap A feature of the configuration is that the electrode layer disposed on the back side is sealed between the plate members without interfering with the first gas flow path and the second gas flow path.

  In the plate-type discharge cell for an ozone generator of the present invention, the cell is constituted by a laminate. The laminated body is a block body formed by joining a plurality of plate members made of a sintered body of high-purity ceramics with a nonmetallic inorganic bonding material, and has high rigidity. Since high-purity ceramics are pre-sintered bulk materials and do not require sintering, deformation associated with sintering does not occur. In addition, due to the high rigidity, deformation at the product stage does not occur. For these reasons, the in-plane uniformity of the discharge gap amount is high.

  In the laminated body block, the raw material gas flows into the closed gap for discharge in the laminated body, that is, the discharge gap whose periphery is sealed, through the first gas flow path formed in the laminating direction in the laminated body. The ozone gas generated in the discharge gap is discharged out of the stacked body through the second gas flow path formed in the stacking direction in the stacked body. Both gases contact only non-metallic inorganic materials including sintered bodies of high-purity ceramics in the laminate. In other words, all of the gas contact members are non-metallic inorganic materials. For this reason, it is possible to effectively avoid contamination from the laminated body block of both the source gas and the ozone gas.

  The plate material may be a circular plate or a square plate such as a quadrangle. In the case of a square plate, the first gas flow path is formed in a horizontally long shape along one of the two parallel side edges of the square plate, and the second gas flow path is formed in a horizontally long shape along the other of the two side edges. It is reasonable to form the electrode layer in a rectangular region sandwiched between these gas flow paths. Thereby, the wide area | region between two square plates can be utilized for an ozone generation area | region.

  The ceramic is preferably alumina having a purity of 80% or more, particularly preferably alumina having a purity of 90% or more, particularly 95% or more. Alumina is suitable because it is inexpensive among ceramics and has chemical resistance and sputtering resistance. Moreover, high purity is preferable in order to increase the cleanliness of ozone gas. The inorganic bonding material is preferably a glass bonding material from the viewpoint of bondability and contamination prevention.

  Of the ceramic plates, the dielectric plate preferably has a thickness of 0.1 to 2.0 mm in order to ensure rigidity and strength and reduce voltage drop. When impurities in the dielectric plate are reduced, a decrease in ozone concentration becomes a problem. In order to solve this problem, titanium oxide is preferably contained in at least a surface layer portion of the dielectric plate in contact with the discharge gap, and titanium oxide is contained in the alumina substrate in an amount of 0.006 to 6% by weight in terms of the amount of Ti element. A sintered body is particularly preferable from the viewpoints of ozone generation characteristics and cleanliness.

  In order to form a discharge gap (a closed gap for discharge) between a pair of dielectric plates, for example, a thin ceramic plate from which a gas flow path has been removed is sandwiched between the dielectric plates as a spacer. Further, a ceramic layer is laminated on at least one of the opposing surfaces of the pair of dielectric plates except for the gas flow path portion. The ceramic layer is printed with paste made of alumina powder and glass powder on the part other than the gas flow path to prevent contamination. After repeating this to a predetermined thickness, firing is performed at a temperature equal to or higher than the melting point of the glass powder. Can be formed. The gap amount is preferably as small as possible in terms of improving the cooling performance and reducing the voltage drop. When the gap amount is small (0.2 mm or less), the latter ceramic layer is preferably laminated.

  The plate-type discharge cell for an ozone generator of the present invention comprises a laminate block formed by joining a plurality of plate materials made of a sintered body of high-purity ceramics with a nonmetallic inorganic bonding material, A closed gap for discharge is formed between two adjacent plates of the plate material, and gas flow paths for source gas and ozone gas are formed in communication with the closed space in the stacking direction in the stack. And the electrode layer disposed on the back side of each of the two plate members for discharge is sealed between the plate members without interfering with the gas flow path. Contamination can be avoided. For this reason, clean ozone gas suitable for a semiconductor manufacturing process etc. can be generated.

  Further, since the deformation of the plate material in the cell manufacturing process and the deformation of the plate material in the product stage can be prevented, the in-plane uniformity of the discharge gap amount is high and the ozone generation efficiency is excellent.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view of a plate-type discharge cell for an ozone generator according to an embodiment of the present invention, FIG. 2 is an enlarged perspective view of a dielectric plate used in the plate-type discharge cell, and FIG. It is a schematic cross section of a discharge cell.

  As shown in FIGS. 1 and 3, the plate-type discharge cell for an ozone generator of the present embodiment has a configuration in which a plurality of square plate members are stacked in the plate thickness direction. The plurality of plate materials are all fired plates of high-purity alumina, and are joined via a glass-based joining layer 50. Positioning through holes are provided at the four corners of each plate member, and the corners are rounded.

  The two middle plates are dielectric plates 10A and 10B. The thickness is 0.2 mm, for example. On both side edge portions of each dielectric plate 10 which are parallel to each other, elongated hole-shaped through holes 11, 11 are provided along each side edge. The through-holes 11 and 11 are for gas distribution, and are provided continuously and linearly in almost the whole area except for both ends of both side edges. The other parallel side edges of each dielectric plate 10, that is, both side edges perpendicular to the through holes 11, 11 are provided with through holes 12, 12 having a long hole shape along each side edge. The through-holes 12 and 12 are for refrigerant circulation, and are provided continuously and linearly in almost the whole area except for both ends of both side edges.

  As shown in FIGS. 2 and 3, in order to form a large number of parallel gas passages 13 extending from one of the through holes 11 and 11 to the other surface of each dielectric plate 10, The ceramic layer 14 is laminated except for the portion. The ceramic layer 14 is obtained by printing a paste made of alumina powder and glass powder on a portion other than the gas flow path on the opposite surface, repeating this to a predetermined thickness (for example, 50 μm), and then at a temperature equal to or higher than the melting point of the glass powder. It is formed by firing.

  An electrode layer 15 is coated on the back surface of each dielectric plate 10. The electrode layer 15 is a metal thin film having a thickness of 5 μm formed by printing and baking silver paste, for example, and is provided in a square region surrounded by the through holes 11, 11, 12, and 12.

  Two adjacent corner portions of the electrode layer 15 protrude from the corner portion of the dielectric plate 10 to form a circular terminal portion 16. Positioning through holes 17 provided at the corners of the dielectric plate 10 are provided at the center of the terminal portion 16. The terminal portions 16 and 16 in one dielectric plate 10A are provided at two adjacent corner portions of the dielectric plate 10A, and the terminal portions 16 and 16 in the other dielectric plate 10B are terminal portions in the dielectric plate 10A. 16 and 16 are provided at two adjacent corner portions of the dielectric plate 10B so as not to overlap.

  The plate materials arranged outside the dielectric plates 10A and 10B are the insulating plates 20A and 20B. The thickness is 2 mm, for example. At both side edges of each insulating plate 20, through holes 21 and 21 for gas circulation having long holes corresponding to the through holes 11 and 11 are provided. The other parallel side edges of each insulating plate 20 are provided with through-holes 22 and 22 for refrigerant circulation having a long hole shape corresponding to the through-holes 12 and 12.

  The plate materials arranged outside the insulating plates 20A and 20B are the slit plates 30A and 30B for forming the refrigerant flow path. The thickness is 0.5 mm, for example. On the both side edges of each slit plate 30 are provided through holes 31 and 31 for gas circulation having a long hole shape corresponding to the through holes 11, 11, 21 and 21. A large number of slits 33, 33,... Are provided in parallel between the through holes 31, 31 in order to form a refrigerant flow path. Both ends of the slits 33, 33... Reach the other parallel side edges of each slit plate 30 so as to overlap with the through holes 22, 22 for circulating the refrigerant.

  The plate members disposed further outside the slit plates 30A and 30B are the cover plates 40A and 40B. The thickness of one lid plate 40A is, for example, 5 mm, and the thickness of the other lid plate 40B is, for example, 2 mm. One cover plate 40A is provided with a gas supply hole 41a and a gas discharge hole 41b communicating with the through holes 31, 31 of the inner slit plate 30A, respectively. A pair of recesses is provided on the back surface of the cover plate 40A so as to correspond to both end portions of the slits 33, 33,..., That is, the through holes 12, 12, 22, and 22. The lid plate 40A is provided with a refrigerant supply hole 42a and a refrigerant discharge hole 42b that communicate with a pair of recesses on the back surface side.

  These plate materials (sintered plates of high-purity alumina) are joined as follows.

  A glass-based bonding paste is applied to the bonding surface of each plate material to a thickness of about 30 μm, for example. The bonding paste is prepared by kneading glass powder with a binder to have a predetermined viscosity. When the application of the bonding paste is finished, the plate material is charged into a heating furnace, and the bonding paste is baked at a temperature of, for example, 850 ° C. or higher, which is the melting point of the glass powder. When the bonding paste is baked, the respective plate materials are overlapped, and the positioning pins 60 are pierced through the through holes at the four corners. The four positioning pins 60 also serve as rod-shaped leads, two of which are electrically connected to the two terminal portions 16 and 16 provided on the back surface of the dielectric plate 10A, and the other two are the dielectric plate 10B. It is electrically connected to the two terminal portions 16 and 16 provided on the back surface. Finally, the stacked plate materials are charged into a heating furnace, and the joining paste is fired at a temperature of, for example, 850 ° C. or higher, which is the melting point of the glass powder.

  By this firing, the dielectric plates 10A and 10B, the outer insulating plates 20A and 20B, the outer slit plates 30A and 30B, and the outer lid plates 40A and 40B are bonded via the glass-based bonding layer 50. Thus, the plate discharge cell of this embodiment is completed. The characteristics of the completed plate discharge cell are as follows.

  By combining the gas flow paths 13 and 13 between the dielectric plates 10A and 10B, a closed space for discharge, that is, a discharge gap 70 is formed between the dielectric plates 10A and 10B. Each thickness of the ceramic layers 14 and 14 forming the gas flow paths 13 and 13 is, for example, 50 μm. For this reason, the gap amount of the discharge gap 70 is, for example, 100 μm. The electrode layer 15 coated on the back surface of the dielectric plate 10 is sealed together with the terminal portions 16 and 16 by the glass-based bonding layer 50 between the dielectric plate 10 and the insulating plate 20 bonded to the outside thereof. And insulated.

  The electrode layer 15 provided on the back side of the dielectric plate 10A is a high voltage electrode. The terminal portions 16 and 16 of the electrode layer 15 are drawn out to the outside of the cover plate 40A by the two rod-shaped leads 60 and 60. On the other hand, the electrode layer 15 provided on the back side of the dielectric plate 10B is a ground electrode. The terminal portions 16 and 16 of the electrode layer 15 are drawn to the outside of the cover plate 40A by another two rod-shaped leads 60 and 60.

  The through holes 11, 11 of the dielectric plate 10, the through holes 21, 21 of the insulating plate 20, and the through holes 31, 31 of the slit plate 30 are continuous in the plate material stacking direction. Gas flow paths 80, 80 are formed in the laminate. Further, the through holes 12 and 12 of the dielectric plate 10 and the through holes 22 and 22 of the insulating plate 20 are continuous in the plate material stacking direction, so that they are communicated with both ends of the slits 33, 33. A horizontally long refrigerant flow path is formed in the laminate.

  In the operation of the plate discharge cell, a predetermined high voltage is applied to the electrode layer 15 provided on the back side of the dielectric plate 10A via the two rod-shaped leads 60, 60, and the remaining two rod-shaped leads 60 are applied. , 60, the electrode layer 15 provided on the back side of the dielectric plate 10B is grounded. At the same time, a raw material gas is introduced into one of the two vertical gas flow paths 80, 80 formed in the stacking direction from the gas supply hole 41a of the cover plate 40A, and two vertical refrigerant flows formed in the stacking direction. Cooling water is introduced into one of the paths from the refrigerant supply hole 42a of the lid plate 40A.

  The source gas introduced into one of the gas flow paths 80, 80 travels from one end to the other end of the discharge gap 70 formed between the dielectric plates 10 </ b> A, 10 </ b> B, and is ozonized during this time to be gas flow path 80. , 80, and is discharged to the outside through the gas discharge holes 41b of the cover plate 40A. The cooling water introduced into one of the two refrigerant channels flows through the slits 33, 33,... Of the slit plates 30A, 30B in the longitudinal direction, passes through the other of the two refrigerant channels, and passes through the other of the two refrigerant channels. It is discharged from the discharge hole 42b. As a result, the discharge gap 70 formed between the dielectric plates 10A and 10B is cooled from both sides.

  As described above, in the plate-type discharge cell for the ozone generator of this embodiment, the raw material gas and the ozone gas pass through the discharge gap 70 between the dielectric plates 10A and 10B from one of the vertical gas flow paths 80 and 80, and the vertical gas flow. It reaches one of the roads 80 and 80. Here, the vertical gas flow paths 80, 80 are formed in a laminate in which high-purity alumina plate materials are bonded together by the glass bonding layer 50, and neither the high-purity alumina plate material nor the glass bonding layer 50 contains a contamination source. It is an inorganic non-metallic material. Further, the discharge gap 70 is formed between the dielectric plates 10 </ b> A and 10 </ b> B made of a high-purity alumina plate by the rib-structure ceramic layer 14 and the glass bonding layer 50, and the ceramic layer 14 is as clean as the glass bonding layer 50. It is an inorganic non-metallic material. Further, the electrode layer 15 is sealed by a glass bonding layer 50 between the dielectric plate 20 and the insulating plate 20 on the back side thereof.

  Thus, the raw material gas and the ozone gas do not directly contact the metal, but pass only through a clean distribution path formed of a clean inorganic non-metallic material that does not contain a contamination source. In other words, all gas contact parts are made of a clean material. Therefore, there is no danger of contamination of the raw material gas and ozone gas by the discharge cell, and ozone gas having a high cleanliness is generated.

  Further, the through holes 11, 21, 31 that form the vertical gas flow path 80 in the stacking direction, for example, the through holes 11, 11 of the dielectric plate 10 are continuously narrowed in the lateral direction along two parallel sides of the dielectric plate 10. Is provided. Further, the through holes 12 and 22 that form the longitudinal refrigerant flow path in the stacking direction, for example, the through holes 12 and 12 of the dielectric plate 10, are thin and continuous in the lateral direction along the other two parallel sides of the dielectric plate 10. Is provided. That is, by arranging the terminal portions 16 and 16 of the electrode layer 15 at the corner portions where the through holes 11 and 12 are abutted, the through holes 11 and 12 of the dielectric plate 10 are located on the side edges of the dielectric plate 10. It is formed in a continuous and narrow manner in the lateral direction along the edge.

  For this reason, the gas circulates in the discharge gap 70 formed between the vertically oriented gas flow paths 80, with a uniform distribution over the entire width direction. Further, since the cooling water flows through the slits 33, 33,... Of the slit plates 30A, 30B with a uniform distribution over the entire width direction, the electrode layers 15, 15 and the discharge gap 70 are efficiently cooled over the entire width.

  Further, the discharge cell is composed of a sintered ceramic plate, and each plate is highly rigid. Moreover, each plate material is reinforced by integration and block formation by lamination bonding. For this reason, the deformation | transformation of the board | plate material in a discharge cell does not arise. Further, the use of the sintered plate eliminates the need for high-temperature sintering of ceramics (high-temperature sintering exceeding 1000 ° C.) in the manufacturing process of the discharge cell, and avoids deformation of the plate material accompanying high-temperature sintering of ceramics. In order to avoid these deformations, the in-plane distribution of the gap amount of the discharge gap 70 formed between the dielectric plates 10A and 10B becomes uniform.

  Thus, in the plate-type discharge cell for the ozone generator of the present embodiment, ozone gas having a high cleanliness is generated, and high-efficiency ozone is achieved by improving the cooling capacity, expanding the electrode area and making the gap amount in-plane uniform. Can be generated.

  In addition, although the said embodiment is a square plate type discharge cell, a disk type discharge cell may be sufficient. In this case, the gas circulation through holes 11 and 11 and the refrigerant circulation through holes 12 and 12 in the dielectric plate 10 are paired with the center of the dielectric plate 10 sandwiched between two intersecting directions (normally two directions perpendicular to each other). It is reasonable to provide the electrode layer 15 at a position where the electrode layer 15 is provided, and it is reasonable to provide the electrode layer 15 in a quadrangular region where the region between the through holes 11 and 11 and the region between the through holes 12 and 12 overlap. Each through hole may have an arc shape along the outer periphery of the dielectric plate 10, but a half-moon shaped through hole in which the outer side is an arc along the outer periphery of the dielectric plate 10 and the inner side is a straight line along the electrode layer 15. The hole area can be increased.

It is a disassembled perspective view of the plate-type discharge cell for ozone generators which shows one Embodiment of this invention. It is an expansion perspective view of the dielectric plate used for the plate type discharge cell. It is a schematic cross section of the same plate type discharge cell.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Dielectric plate 11,12 Through-hole 13 Gas flow path 14 Ceramic layer 15 Electrode layer 16 Terminal part 20 Insulating plate 21,22 Through-hole 30 Slit plate 31 Through-hole 33 Slit 40 Lid plate 41 Gas hole 42 Refrigerant hole 50 Glass bonding layer 60 Rod-shaped lead 70 Discharge gap 80 Vertical gas flow path

Claims (4)

  It consists of a laminate block made by joining a plurality of plates made of a sintered body of high-purity ceramics with a nonmetallic inorganic bonding material, and discharges between two adjacent plates among the plurality of plates. A first gas flow path for introducing a source gas into the closed gap and a second gas flow path for deriving ozone gas from the closed gap are formed in the stacking direction in the stacked body. Are formed in communication with the closed space, and electrode layers disposed on the back sides of the two plate members for discharging in the closed gap include the first gas channel and the second gas channel. A plate-type discharge cell for an ozone generator, wherein the plate-type discharge cell is enclosed between plate materials without interfering.   The plate member is a rectangular square plate, and the first gas channel is formed in a horizontally long shape along one of two parallel side edges of the square plate, and the second gas channel is formed on the second side edge. 2. The ozone generator according to claim 1, wherein the ozone generator is formed in a horizontally long shape along the other side of the first gas channel, and the electrode layer is disposed in a rectangular region sandwiched between the first gas channel and the second gas channel. Plate type discharge cell.   The plate discharge cell for an ozone generator according to claim 1, wherein the ceramic is alumina having a purity of 80% or more.   The plate-type discharge cell for an ozone generator according to claim 1, wherein the inorganic bonding material is a glass bonding material.