JP5028596B2 - Gas distributor - Google Patents

Description

  The present invention relates to a bubble generation technique for supplying gas in a bubble form into a liquid such as water. Such a bubble generator is used for an aeration tank or the like in wastewater treatment.

When organic sludge treatment such as sewage and industrial wastewater is treated with activated sludge, an air diffuser that introduces air into the aeration tank and supplies oxygen is used. In a diffuser, a porous body in which ceramic or plastic fine particles are sintered at a high temperature into a plate shape or a cylindrical shape is widely used.
It is known that the performance of an aeration tank in conventional wastewater treatment can be improved by eliminating the rate of oxygen supply to activated sludge as the oxygen dissolution rate in the liquid is higher. For this reason, a porous plate with fine circular holes or a porous plate with randomly shaped holes is often used as a gas distributor, thereby generating bubbles of smaller size per unit volume. We are trying to increase the gas-liquid contact area. Actually, it is known that the size of bubbles generated from a conventional gas disperser in a water-air system is usually about 3 to 10 mm.
On the other hand, attempts have been made to make the generated bubble size smaller by improving the forced liquid convection in the vicinity of the gas disperser or by using a microbubble generator using the shear force of a strong liquid.

If the generated bubbles are made smaller, the gas-liquid contact area can be increased, and the oxygen dissolution efficiency can be improved. For this purpose, it is necessary to make the opening diameter of the diffuser surface smaller.
In a porous sintered body of fine particles of ceramic or plastic, in order to reduce the opening diameter of the diffuser surface, sintering is performed using a smaller particle size. Since the ceramic sintered body has low bending strength, the thickness needs to be 10 mm or more in order to prevent cracking due to external force or air pressure. In addition, since the ceramic sintered body is easily broken, the diffusion area per sheet must be reduced, which increases the number of installations and increases the cost.
Air diffusers using rubber membranes have been developed. This is a device that uses a rubber thin film with slits. When aeration occurs, the rubber expands to open the slits and generate bubbles, and when aeration stops, the slits close to prevent the backflow of sewage.
In both cases, the hole diameters on the diffuser plate surface are uneven, so that depending on the flow rate of the aeration gas, holes that do not generate bubbles are generated, or the generated bubble sizes are different for each hole.

Examples of prior literature include the following.
In Patent Document 1 (Japanese Patent Laid-Open No. 2005-177551), the mesh cloth 1 used for the air diffusion surface is woven with 100 to 1000 mesh using yarn having a wire diameter of 10 to 100 μm, and the size of the opening is set. There has been proposed an air diffuser capable of generating bubbles having a diameter of about 1 mm by being constituted by a cloth having a diameter of 5 to 200 μm.
In Patent Document 2 (Japanese Patent Laid-Open No. 2001-259395), a gas-liquid two-phase flow formed by taking a gas phase into a liquid is discharged into the liquid to be processed, thereby supplying fine bubbles to the liquid to be processed. In the aerator, a discharge flow forming tank opened at the bottom and immersed in the liquid to be treated, and the discharge flow in a jet direction to be a swirl flow swirling in the tank along the peripheral wall of the discharge flow forming tank A liquid supply means for pressurizing and supplying a liquid to the forming tank; and the discharge flow forming tank by naturally sucking the gas by the swirling flow from a gas introduction port provided in the discharge flow forming tank so as to face the discharge port. Gas supply means for supplying a gas to the discharge flow forming tank, and a gas-liquid two-phase flow formed by pressurizing and supplying a liquid to the discharge flow forming tank is diffused and jetted into the liquid to be processed from the discharge port. Air that can supply air bubbles of about μm size Over data it has been proposed.
In Patent Document 3 (Japanese Patent Laid-Open No. 2005-74348), a hollow strand made of a stainless steel strand is twisted into a coil shape and hollow, and air sent from a compressor is used as a gap between the strands. From 0.5 to 15 mm in diameter with a mechanism that can adjust the amount of bubbles and the fineness of the bubbles by adding twist along the circumferential direction to the hollow stranded wire. An aeration apparatus that generates bubbles centered on a diameter of 5 mm has been proposed.
Patent Document 4 (Japanese Patent Laid-Open No. 10-235390) discloses a diffuser tube having a plurality of diffused holes with a diameter of 4 to 8 mm facing downward, and a rubber reverse attached to the diffuser holes of the diffuser tube. There is disclosed an air diffuser that includes a stop valve and that has a slit formed on a hemispherical surface of the rubber check valve that opens when aerated and closes when not aerated.
In Patent Document 5 (Japanese Patent Laid-Open No. 10-180287), there are provided a plurality of air ejection holes having an inner diameter of 3 to 50 mm drilled in the wall of a hollow body, and a vibrator movable in the axial direction of the air ejection holes. A fitted air diffuser is disclosed.

JP 2005-177551 A JP 2001-259395 A JP 2005-74348 A Japanese Patent Laid-Open No. 10-235390 JP-A-10-180287

  The gas disperser provided with a circular opening mainly used in the past can reduce the bubble size to at least about 3 mm. In addition, it is expensive to manufacture a gas disperser having many finer holes. On the other hand, if an additional device such as a forced convection device or a liquid pump is used, or a gas disperser recently attracting attention called a microbubble generator, even smaller bubbles can be generated, but the accompanying power cost is large, There are practical problems. In addition, there are few variations in the size of the gas disperser itself, and it cannot be increased in size or reduced freely. An object of this invention is to provide the technique which can generate the bubble which has a diameter of 1 mm or less, without requiring a forced convection apparatus and a microbubble generator. Moreover, it aims at providing the technique which can generate the bubble which has a diameter of 1 mm or less using the structure different from a woven fabric or a hollow twisted yarn.

  The present invention has been completed by discovering that bubbles having a diameter of 1 mm or less can be generated by discharging gas into a liquid such as water from a non-circular opening having a width of 30 μm or less. The main configuration of the present invention is as follows.

The main configuration of the present invention is as follows.
(1) The gas discharge hole has a rectangular slit shape with a maximum short side of 30 μm or less and a long side length of 1 to 30 mm, and a plurality of slit-like shapes in which the interval between adjacent gas discharge holes is 3 mm or more. A gas disperser that includes a gas discharge hole and generates a bubble having a diameter of 1 mm or less by setting a gas flow rate per slit-like gas discharge hole to 50 cc / min or less,
The gas distributor is composed of a planar plate disposed at both ends and a plurality of intermediate frames disposed between both planar plates,
The intermediate frame is formed with a groove communicating from the central space to the outside, and the groove constitutes the gas discharge hole.
(2) The gas distributor according to (1) , wherein a plurality of grooves formed in the intermediate frame are formed on the same intermediate frame.
(3) The intermediate frame has a frame having a slit width thickness in which a notch having the same length as the slit is formed, and a plane having the same thickness as the interval between adjacent gas discharge holes and having no notch. The gas distributor according to (1) or (2) , wherein the gas distributor is configured by combining with a frame .
(4) The groove formed in the intermediate frame is based on a frame having the same thickness as the interval between adjacent gas discharge holes, and a coating film having a thickness corresponding to the width of the slit is formed on the surface of the frame excluding the groove. The gas disperser according to (1) or (2), wherein

In the present invention, a gas distributor having slit-like fine holes and a simple design method thereof can be provided. If this is used, it is possible to generate bubbles having a diameter of 1 mm or less without using any additional power, and considering the cost, it is sufficient that bubbles of about 100 μm can be dispersed in applications such as wastewater treatment. Up to 10 μm is not necessary. Thereby, a sufficiently high oxygen dissolution rate can be obtained.
By combining a plurality of intermediate frames provided with notches serving as openings, it is possible to freely design the size with simple and few types of parts. In addition, maintenance such as disassembly and reassembly is easy.
Since the structure is simple, scale-up, scale-down, and maintenance are easy. Moreover, since no external power other than the gas compressor is required, it is easy to put into practical use.
Further, since the generated bubble size is 1 mm or less, the gas absorption rate is increased, which is advantageous in a chemical reaction or wastewater treatment in which gas absorption is rate-limiting.

In this proposal, the hole to be opened on the gas distributor is not a circular hole but a non-circular shape such as a rectangle (or a triangle). By generating bubbles from these holes, the separation of bubbles from the surface of the gas distributor was promoted, and finer bubbles were successfully generated. The principle is as follows.
For example, in the case of a water-air system, an interfacial tension of about 70 mN / m works on the bubble surface, and thus a force to keep the bubble cross section circular is working. If the shape of the hole, which is the place where bubbles start to expand to grow into a spherical shape, is a non-circular shape such as a rectangle, a large unreasonable effect occurs between the cross-sectional shape of the bubble in contact with the hole and the hole shape. An unstable point occurs in a part of the side. This triggers the destruction of the “bubble neck” that connects the bubbles and the holes of the gas disperser and begins to rise as a single bubble. This occurs at an earlier stage than bubbles that are stably generated from a circular hole, so that the bubbles can be miniaturized. This mechanism does not use forced liquid flow (pump + electrical energy) or additives (chemicals + purchase costs), and uses only natural phenomena (buoyancy, surface tension, wettability, etc.), so it has very low energy It is.

The present invention embodies a non-circular slit having a short side width of 30 μm or less as a gas outlet. The shape of the slit is a rectangle, a triangle, a trapezoid, or the like. A slit having a longer length than a width is more suitable than a circle or square. In terms of production, a 30 μm square or a circular hole is too small and difficult. In addition, even if R is attached to the short side, a slit having a long side sufficiently longer than the short side can be regarded as a non-circular meaning in the present invention.
The length of the long side of the slit is at least 10 times the short side. Considering ease of manufacture, there is no problem if it is 1 mm or more. In the present invention, since the slit length does not significantly affect the size of the bubble, there is no particular upper limit. However, it has been experimentally confirmed that sufficiently small bubbles are generated even at 30 mm.
Observing the occurrence of bubbles, the formation force of bubbles to become stable spheres works, so when assuming a long slit with a width of 30 μm, bubbles along the entire shape of the slit do not occur, 30 μm It has been observed that bubbles are generated from a part of the slit in a state where the width is limited. That is, in the case of a long slit, a plurality of bubbles are generated simultaneously from one slit. If the length is longer than the width, there is no problem in principle on the restriction of the length. However, in practical use, it is practical to provide a length of 1 mm or more in consideration of manufacturability and air pressure loss. If the slit length is increased, even if clogging occurs in one part, bubbles can be generated from the other part.
If the bubbles are small, they will not merge even if they come into contact with each other, and the independence will be high, the floating time in water will be long, and the ability to supply gas to water can be enhanced.

  The gas disperser of the present invention is provided at the tip or middle part of a gas introduction path fed from an air pump or the like, and is disposed at the middle or bottom surface of a liquid such as water, and is 1 mm or less from the gas discharge slit. It generates bubbles. The general outline of the gas disperser of the present invention is a hollow box shape provided with one to many slits for generating bubbles, and one end face is connected to a gas line on the side of an air supply means such as an air pump. The other wall surface has a delivery port for sending gas to the outside as necessary, and a slit for generating bubbles is provided on the peripheral surface. The provided surface is not limited to one surface but can be provided on a plurality of surfaces. For example, when the gas distributor is a hollow rectangular parallelepiped, an inlet for introducing gas can be provided on the front surface, a large number of slits can be provided on the upper surface, and an air supply port can be provided on the rear surface. Note that the gas discharge slit is not limited to the upper surface, but may be a side surface or a bottom surface. When a plurality of slits for generating bubbles are provided, stable bubbles can be generated even if the gas flow rate is increased if the distance between the front, rear, left and right slits is greater than 2 mm.

  The gas discharge slit can be formed by directly drilling a slit having a width of 30 μm or less directly on the wall surface of the gas distributor body with a laser or the like, but is not practical in terms of processing time and cost.

As another means, a thin plate having the same thickness as the slit width is prepared, and a frame having a space at the center is formed, and a part of the frame is cut into a groove shape that leads from the center space to the outer surface. Create a frame with a notch. A plurality of notches can be provided.
On the other hand, a frame body without a notch is prepared, and the intermediate frame body with a groove having the same depth as the width of the slit is manufactured by stacking and integrating with the notched frame body. As the thickness of the frame body not provided with the notch, a frame body having the same thickness as the notched frame body or a thicker frame body can be used. The thickness can also be adjusted by using a plurality of frames that are not provided with notches. It is preferable to use a frame having a thickness suitable for the slit interval.
A metal foil can be used as the material of the frame to be cut. For example, aluminum foil, copper foil, titanium, stainless steel, tin and the like and alloys thereof can be used. For these metals, a metal foil sheet having a thickness of 1 to 30 μm has been put to practical use in other applications.
By continuously laminating the intermediate frames, it is possible to form a slit that becomes a gas discharge hole. The direction of stacking can be vertical and horizontal, and the number of slits can be flexibly changed by selecting the number.
A front plate body and a rear plate body in which an air inlet is formed before and after these intermediate frames are arranged and integrated by bolts and nuts penetrating the frame portion to form a gas distributor body. Can do. Screwing is easy for maintenance such as disassembly.
As a means for integrating a plurality of intermediate frames, one or a plurality of through holes are provided in the frame portion, and the whole is tightly fastened with bolts, or can be bonded or welded.

  Another method is to prepare a frame having a thickness greater than or equal to the slit width, and to cut out a groove having a depth corresponding to the slit width from the central space portion toward the outside by a method such as cutting. . By using this grooved frame body as an intermediate frame, the gas distributor with a gas discharge slit can be obtained by combining and integrating as described above.

Another method is to prepare a frame and a tape-shaped masking material having a slit width thickness and a slit length width, and masking by masking the masking tape from the central opening of the frame outward. By applying a resin or the like to the entire frame surface and curing it to form a resin film and removing the masking tape, an intermediate frame body having grooves corresponding to slits can be formed. Combination integration can be performed in the same manner as described above.
When an adhesive synthetic resin is used as the synthetic resin to be applied, lamination adhesion can be performed simultaneously. As other coating agents, glass, plating, enamel and the like can be used.

  The shape of each intermediate frame described above is not particularly limited as long as a space through which gas can pass is provided at the center, such as a square, a circle, an ellipse, a triangle, and an irregular shape.

The material is not particularly limited, but a thin frame is used, so that it is preferable to be metallic. When masking is performed, a synthetic resin such as an epoxy resin or a urethane resin can be used.
The metal is preferably made of a material having high corrosion resistance according to the usage environment such as water. For example, stainless steel, copper, aluminum, iron, titanium, nickel, chromium, tin, etc., and alloys thereof can be used. When using dissimilar metals, it is preferable to consider electric corrosion. Moreover, when using it for food-related, it is necessary to consider the influence on a human body.

  The gas disperser of the present invention can be used for the purpose of generating bubbles in the liquid. For example, it can be used for aeration in wastewater treatment facilities, fish and shellfish culture tanks, supply of air to rivers, lakes, oceans, etc., bioreactors, and food / beverage products mixed with gas components.

  The gas disperser of the present invention has a large degree of freedom in changing the size, is easy to perform maintenance such as disassembly and assembly, can use normal air supply means, has few restrictions on installation locations, and has a low running cost. It is an invention that is excellent in use.

The gas distributor of Example 1 is demonstrated with reference to FIGS. FIG. 1 is an exploded view of components of the gas distributor of the present embodiment, FIG. 2 is an assembly schematic diagram, and FIG. 3 is an enlarged view of an intermediate frame.
The gas distributor 1 according to the present embodiment includes a plurality of slit plates between a front plate 2 provided with a gas inlet 21 which is a plate connected to a gas line and a rear plate 6 which is a mekura plate. The frame 3 is arranged and configured. The intermediate frame 3 is provided with a groove 4 serving as a gas discharge slit 7 and communicates with the central space portion 32. A hole corresponding to the position of the through hole 33 provided in the frame part 34 of the intermediate frame 3 is provided from the front plate 2 to the rear plate 6, and a through bolt (not shown) is inserted and tightened with a nut. And integrated into the gas distributor 1 of this embodiment.
The intermediate frame 3 shown in FIG. 3 is a rectangular frame having a central space 32 at the center, and has an intermediate frame thickness 31 of 3 mm, a groove having a depth of 30 μm and a width of 10 mm. . A plurality of through holes 33 are formed in the frame portion 34. In the figure, 11 through holes are provided, but it is sufficient if the front and rear frame bodies can be in close contact with each other. It is not necessary to pass bolts through all the through holes, and the number of through holes itself is sufficient. It is. The intermediate frame 3 is sandwiched and laminated between the front plate 2 and the rear plate 6 with the direction of the groove 4 aligned to form a gas distributor 1 in which a gas discharge slit 7 is formed.

When the gas disperser 1 is submerged in water and a gas such as air is sent from the gas line through the inlet 21, bubbles having a diameter of 1 mm or less can be generated from the gas discharge slit 7.
The figure shows an example in which one groove is formed, but a plurality of grooves can be provided as shown in Example 4 below.

The present embodiment is an example using an intermediate frame made by a manufacturing method different from that of the first embodiment.
In this embodiment, a rectangular frame with a thickness of 30 μm is cut into the same length as the groove width of the first embodiment, and a frame 51 with a notch provided with a notch 53 and a frame with a thickness of 3 mm without a notch. The intermediate frame 3 is formed by forming the groove 54 by combining with the body 52. In this embodiment, an aluminum foil is used as the 30 μm thick foil, but the present invention is not limited to this.

In this embodiment, the groove of the intermediate frame is manufactured by using a masking method.
Cover the frame part of the frame body 52 having a thickness of 3 mm from the central space part to the outside with an aluminum foil tape having a thickness of 30 μm and a width of 10 mm (a). In this masked state, the entire frame part is painted with an epoxy resin paint. Then, a coating film 56 having a thickness of 30 μm is formed (b) and (c), and the aluminum foil tape is removed to form an intermediate frame 3 (d) in which grooves 54 are formed.
It is possible to further change the performance by adding a hydrophilic agent or a water repellent as a paint. By adding the hydrophilic agent, water is attracted to the paint surface of the gas release slit, so that the generated bubbles tend to be small. When the water repellent is used, the separation of bubbles is worsened and the bubbles tend to be larger. The water repellent and the hydrophilic agent can be used in other examples by a technique such as spraying.

In this embodiment, the gas distributor 1 using the intermediate frame 3 provided with a plurality of grooves 4 is used. Any of Examples 1 to 3 can be used as a method of forming the plurality of U-shaped grooves.
In this way, gas can be dispersed by stacking a large number of slit plates, fastening them with metal fittings, closing both end faces, and supplying gas from one end face. Furthermore, the number of holes can be changed freely by simply changing the number of stacked layers. The surface on which the slit is provided can be provided on the side surface, the bottom surface, or a plurality of directions in addition to the top surface, and the degree of freedom in layout is high.

[Bubble generation evaluation test]
The generation of bubbles was observed by changing the size and interval of the gas discharge slit and the gas flow rate.
Basically, Example 1 was used, but it is easy to use the method of Example 2 to change the shape and interval of the gas discharge slit. It was created.
An enlarged view of the gas discharge slit is shown in FIG. Assuming intermediate frame bodies 31a and 31b stacked in front and rear, two gas discharge slits 41 and 42 having a slit width SW and a slit length SL are provided at an interval x.

[Bubble generation evaluation test 1 Example of generated bubbles using Example 1 of the present application]
Bubbles generated by setting the gas discharge slit to the upper surface of the gas distributor in a water tank containing tap water with a slit width of 30 μm, a slit length of 10 mm, a gas flow rate of 10 cc / min, and nitrogen gas were observed. It is understood that the bubbles generated from the scale are 1 mm or less by placing a ruler adjacent to the gas discharge slit. It is also observed that a plurality of bubbles are generated concurrently from the gas discharge slit, and bubbles are generated by being regulated by the slit width rather than the slit length. The size of the bubbles is uniform with a diameter of 1 mm or less, and the state is also observed independently without coalescence.

[Bubble generation evaluation test 2 Relationship between slit width and bubble diameter]
Using one, two, or three 30 μm thick aluminum foils, the slit width was changed, and the state of bubble generation was observed. The result is shown in FIG.
It can be seen that the generated bubbles have a bubble diameter of 1 mm or less at a slit width of 30 μm. It can also be seen that when the slit width is 60 μm, the bubble diameter is 3 mm, which increases rapidly. It is clear that bubbles with a slit width of 30 μm or less and 1 mm or less can be obtained.

[Bubble generation evaluation test 3 Relationship between slit interval and gas generation limit gas flow with a diameter of 1 mm or less]
The limit gas flow rate that can stably generate a bubble diameter of 1 mm or less was measured by changing the slit interval a. The gas flow rate is cc / min per slit. Since the bubbles become larger as the gas flow rate increases, the conditions under which small bubbles can be stably generated were sought. The result is shown in FIG.
When the distance between the slits is 2 mm or less, the gas flow rate capable of stably generating small bubbles is 6 cc / min or less, and when 3 mm, small bubbles can be stably generated up to 50 cc / min. It is clear that a large gas flow rate can be supplied with a slit spacing greater than 2 mm.

[Bubble generation evaluation test 4 Relationship between slit width generated by gas flow rate and bubble size]
Using three types of gas dispersers with slit widths of 30, 60, and 90 μm, the supply gas flow rate and the size of the generated bubbles were observed. The result is shown in FIG.
When the slit width is increased by 60, 90 μm, a large amount of gas can be supplied, but the bubble diameter is around 3 mm. With a slit width of 30 μm, a bubble diameter of about 0.5 mm is obtained. Although the gas flow rate per slit is small, since small bubbles can be suspended in water for a long time, the actual ability to dissolve gas in water is high. Further, it is possible to easily increase the amount of gas released by increasing the number of slits.

[Bubble generation evaluation test 5 Relationship between slit length and bubble size]
Using three types of gas dispersers with a slit width of 30 μm and slit lengths of 10, 20, and 30 mm, changes in the gas flow rate and the size of the generated bubbles were observed.
In the case of slits of any width, even when the gas supply amount was increased, the bubble diameter was stable at 1 mm or less, and it was confirmed that the influence of the slit length was small. This point is also shown to be observed in the bubble generation situation photograph in FIG.

(Summary of results)
As a result, it was found that when the slit width is 30 μm or less, bubbles having a diameter of 1 mm or less that are not affected by the slit length can be stably generated.
A gas disperser with slit-like fine holes and its simple design method could be provided. If this is used, bubbles having a diameter of 1 mm or less can be generated with little additional power, and a high oxygen dissolution rate with excellent cost performance can be realized.
By combining a plurality of intermediate frames provided with notches serving as openings, the size can be freely designed with fewer parts. In addition, maintenance such as disassembly and reassembly is easy.
Since the structure is simple, scale-up, scale-down, and maintenance are easy. Moreover, since no external power other than the gas compressor is required, it is easy to put into practical use.
Further, since the generated bubble size is 1 mm or less, the gas absorption rate is increased, which is advantageous in a chemical reaction or wastewater treatment in which gas absorption is rate-limiting.

Exploded view of components of gas distributor according to embodiment 1 Assembly schematic diagram of gas distributor of Example 1 The enlarged view of the intermediate frame of Example 1 The figure which shows the method of manufacturing the intermediate frame using the bonding method used for Example 2 The figure which shows the method of manufacturing the intermediate frame using the masking method used for Example 3 Example 4 Gas Disperser Enlarged view of the gas release slit The figure which shows the bubble generation state using this-application Example 1 Graph showing the relationship between slit width and bubble diameter The graph which shows the relationship between a slit space | interval and the generation | occurrence | production limit gas flow rate of a bubble below diameter 1mm Graph showing the relationship between the slit width generated by the gas flow rate and the bubble size Graph showing the relationship between slit length and bubble size

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas distributor 2 Front plate body 21 Inlet 3 Intermediate frame 31 Intermediate frame thickness 31a, 31b Intermediate frame 32 Central space part 33 Through-hole 34 Frame part 4 Groove 51 Notched frame 52 Frame 53 Notch 54 groove 55 masking tape 56 coating film 6 rear plate 7 gas release slit 41, 42 gas release slit

Claims (4)

The gas discharge holes are rectangular slits having a maximum short side of 30 μm or less and a long side of 1 to 30 mm, and a number of slit-like gas discharge holes having an interval between adjacent gas discharge holes of 3 mm or more. A gas distributor that generates bubbles with a diameter of 1 mm or less by setting the gas flow rate per slit-like gas discharge hole to 50 cc / min or less,
The gas distributor is composed of a planar plate disposed at both ends and a plurality of intermediate frames disposed between both planar plates,
The intermediate frame is formed with a groove communicating from the central space to the outside, and the groove constitutes the gas discharge hole. Grooves formed in the intermediate frame body, a gas distributor according to claim 1, characterized in that it is formed with a plurality of the same intermediate frame on the body. An intermediate frame having a slit width thickness in which a notch having the same length as the slit is formed, and a flat frame having the same thickness as the interval between adjacent gas discharge holes and having no notch The gas disperser according to claim 1 , wherein the gas disperser is configured by combining them . The groove formed in the intermediate frame is based on a frame having the same thickness as the interval between adjacent gas discharge holes, and a coating film having a thickness corresponding to the width of the slit is formed on the surface of the frame excluding the groove. The gas disperser according to claim 1 or 2, characterized by the above.