Diffuser and manufacturing method thereof

Abstract

To provide a diffuser that can be easily manufactured with an inexpensive raw material, and a manufacturing method of the diffuser.SOLUTION: A diffuser 2 is formed of a porous body including combustion ash and a binder. The diffuser 2 allows received gas to pass therethrough so that the gas is changed to fine bubbles, and discharges the fine bubbles to the inside of liquid. The diffuser 2 has pressure resistance of 0.2 MPa or more, and is configured such that, when the diffuser 2 receives pressurized gas from the outside, the diffuser 2 can discharge the fine bubbles to the inside of the liquid at a flow rate of 200 L / min or more per unit area 1 m2 from a surface of the diffuser 2.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an air diffuser and a method for manufacturing the same. [Background technology]

[0002] Diffuser plates are known that receive gas from the outside and release fine bubbles into a liquid. Diffuser plates are used in a variety of fields, such as neutralizing concrete wastewater and aeration in aquaculture farms. Ceramic diffuser plates are widely used. Patent Document 1 discloses an air diffuser plate in which a plurality of air diffusion holes are formed in a thin metal plate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-158631 Summary of the Invention [Problem to be solved by the invention]

[0004] The diffuser plate in Patent Document 1 is manufactured by processing a thin metal plate, which results in labor-intensive manufacturing and high manufacturing costs. Similar problems exist with ceramic diffuser plates. Because diffuser plates are consumables and need to be replaced periodically to maintain their performance, there is a demand for them to be available at the lowest possible cost. These problems are not limited to diffuser plates, but also exist with diffusers of other shapes, such as diffuser cylinders.

[0005] The present invention has been made based on the above background, and aims to provide an air diffuser that can be easily manufactured using inexpensive raw materials, and a method for manufacturing the same. [Means for solving the problem]

[0006] In order to achieve the above object, the air diffuser according to the present invention comprises: Includes combustion ash and binder It is a fired body of a molded body. The diffuser is made of a porous material and converts the received gas into fine bubbles by passing the gas through it and then releases the bubbles into the liquid. The air diffuser is It has a pressure resistance of 0.2 MPa or more, and when pressurized gas is received from the outside, the diffuser is 2 It is designed to be able to release fine bubbles into the liquid at a flow rate of 200 L / min or more per 、 The binder includes at least one of clay and a cellulose-based water-soluble polymer. . [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an air diffuser that can be easily manufactured using inexpensive raw materials, and a method for manufacturing the same. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a front view showing a configuration of an air diffusion plate according to an embodiment of the present invention. FIG. [Figure 2] 2 is a cross-sectional view of the air diffuser plate of FIG. 1 taken along line AA. [Figure 3] 3 is a flowchart showing a flow of a method for manufacturing an air diffusion plate according to an embodiment of the present invention. [Figure 4] 3 is a flowchart showing the flow of an assembly method for an air diffuser according to an embodiment of the present invention. [Figure 5] FIG. 2 is a photograph of the appearance of a test specimen fired at a firing temperature of 1000° C. in Example 1. [Figure 6] FIG. 2 is a photograph of the appearance of a test specimen fired at a firing temperature of 1100° C. in Example 1. [Figure 7] FIG. 2 is a photograph of the appearance of a test specimen fired at a firing temperature of 1200° C. in Example 1. [Figure 8] FIG. 10 is a diagram showing the blending amounts of raw materials of test specimens in Example 2. [Figure 9] FIG. 10 is a photograph of the appearance of a test specimen after firing in Example 2. [Figure 10]FIG. 10 is a diagram showing the component ratios of clay, combustion ashes A and B in Example 3. [Figure 11] FIG. 10 is a photograph of the appearance of a test specimen after firing in Example 3. [Figure 12] 10 is a photograph showing a test specimen being produced by a slurry molding method in Example 4. FIG. [Figure 13] FIG. 10 is a photograph of a test specimen being produced by the slice molding method in Example 5. [Figure 14] FIG. 10 is a diagram showing the results of a performance test of the air diffusing plate in Example 6. [Figure 15] FIG. 10 is a schematic diagram showing the configuration of a test device for pH measurement in Example 6. [Figure 16] 1 is a graph showing the change in pH value over time in Example 7. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an air diffuser and a manufacturing method thereof according to an embodiment of the present invention will be described in detail with reference to the drawings. In each drawing, the same or equivalent parts are designated by the same reference numerals. In the embodiment, an air diffuser plate will be used as an example of the air diffuser.

[0010] The air diffuser 1 is a device that is installed in a liquid and receives compressed gas to generate fine bubbles in the liquid. The fine bubbles emitted by the air diffuser 1 are, for example, fine bubbles with a diameter of 2.5 mm or less and are formed from any gas, such as air, oxygen, or carbon dioxide, depending on the application. The liquid in which the air diffuser 1 is installed can be any liquid, such as water. The air diffuser 1 can be used, for example, to neutralize alkaline wastewater such as concrete wastewater, to supply carbon dioxide gas for the growth of aquatic plants such as algae, and to supply oxygen or air for land-based aquaculture and sewage treatment. The following description will be given using an example in which air is used as the gas and water is used as the liquid.

[0011] As shown in Figure 1, the air diffuser 1 includes an air diffuser plate 2 that receives compressed air and generates fine bubbles that are released into water, and a case 3 that is attached so as to cover part of the air diffuser plate 2 and supplies compressed air to the air diffuser plate 2. The air diffuser plate 2 has a pair of opposing surfaces, receiving air on one surface (the back surface) and releasing fine bubbles containing air from the other surface (the front surface). The air diffuser plate 2 is formed of a porous material with numerous internal pores, and the compressed air that flows in from one surface is converted into fine bubbles by passing it through the numerous pores, and the fine bubbles are then released from the other surface.

[0012] The diffuser plate 2 is, for example, disk-shaped. Compared to diffuser plates of other shapes, for example, rectangular shapes, the disk-shaped diffuser plate has no corners and is less likely to break, and high-pressure air does not concentrate locally, making it easier to generate uniform fine bubbles from the entire surface. The diffuser plate 2 can be formed in any size, but considering the efficiency of the number of plates to be installed in the equipment, the area of ​​the diffuser plate 2 is preferably 100 cm or less. 2 As an example, the dimensions of the disk-shaped air diffuser plate 2 are 165 mm in diameter and 15 mm in thickness.

[0013] The case 3 seals the side and back sides of the air diffusion plate 2 and is attached to the air diffusion plate 2 so that the front side is exposed. The case 3 comprises a main body 3a that supplies air toward the back side of the air diffusion plate 2 and a connecting member 3b to which a hose that supplies air to the main body 3a is connected. The main body 3a is formed in a shape corresponding to the air diffusion plate 2 and is a concave member with an opening for attaching the air diffusion plate 2.

[0014] As shown in FIG. 2, the main body 3a receives air supplied from the connecting member 3b in the space 3c and supplies it toward the air diffusion plate 2 installed above the space 3c. The main body 3a has a ring-shaped step 3d for installing the air diffusion plate 2 above the space 3c. The air diffusion plate 2 is sealed to the case 3 so that air does not leak through the gap between the case 3. Specifically, the air diffusion plate 2 is adhered to the step 3d using an adhesive, and the gap between the air diffusion plate 2 and the case 3 is sealed using a sealant.

[0015] The diffuser plate 2 is a fired body (ceramics) obtained by firing a mixture containing combustion ash. Specifically, the diffuser plate 2 is obtained by mixing combustion ash with a binder, adding water to the mixture, molding it into a desired shape, and then firing the resulting molded body. As a result of extensive research, the inventors have found that by optimizing the composition and blending ratio of the raw materials, the components of the combustion ash, and the firing conditions, it is possible to manufacture a diffuser plate 2 that can uniformly spray bubbles from the entire surface using a simple manufacturing process, even if the raw materials contain combustion ash.

[0016] The raw materials for the diffuser plate 2 include combustion ash and a binder. Other additives may be added to the raw materials for the diffuser plate 2. Combustion ash is the main component of the raw materials for the diffuser plate 2, and is, for example, coal ash or biomass combustion ash. Coal ash is ash obtained by burning coal, and is preferably fly ash. Fly ash is coal ash generated when pulverized coal is burned and collected using a dust collector. Biomass combustion ash is ash obtained by burning biological resources derived from plants and animals, such as wood, livestock manure, sewage sludge, and agricultural residues. Combustion ash is continuously emitted from thermal power plants, so it can be obtained stably and inexpensively. The raw materials for the diffuser plate 2, excluding moisture, preferably contain at least 50 wt% combustion ash.

[0017] It is preferable to select combustion ash with as low a calcium and iron content as possible, as calcium and iron are factors that cause shrinkage and cracking of the fired body. The calcium and iron content of the combustion ash is preferably lower than that of the clay to be mixed with it. Specifically, for example, it is preferable that the calcium and iron content of the combustion ash is 5 wt% or less.

[0018] Binders, also called binding materials, bind combustion ash particles together. Examples of binders include clay and cellulose-based water-soluble polymers. Of these, clay is particularly suitable as a binder due to its excellent toughness. An example of a cellulose-based water-soluble polymer is carboxymethyl cellulose (CMC). Multiple types of binders may be mixed with the combustion ash. The weight ratio of the binder contained in the raw materials of the air diffuser plate 2 excluding moisture is 50 wt% or less, but to prevent cracking and deformation during drying and firing, it is preferable that it be 30 wt% or more and 50 wt% or less. The configuration of the air diffusion device 1 and the air diffusion plate 2 has been described above.

[0019] (Manufacturing method) Next, a method for manufacturing the air diffuser plate 2 according to the embodiment will be described with reference to Fig. 3. The air diffuser plate 2 can be manufactured by either a casting method or a press molding method. In both the casting method and the press molding method, the air diffuser plate 2 can be manufactured into any shape by changing the mold. Hereinafter, an example will be described in which coal ash and clay are used as raw materials for the air diffuser plate 2.

[0020] First, water is added to the raw materials and mixed to create a mixture (step S11). In the slip casting method, coal ash and clay are mixed, and water is added and stirred to create a slurry. On the other hand, in the press molding method, coal ash and clay are mixed, and water is added and kneaded to create a clay-like mixture.

[0021] Next, the mixture prepared in step S11 is molded (step S12). In the casting method, the slurry is poured into a mold and the surface shape of the slurry is adjusted using a scraper. The mold used in the casting method does not need to be strong and is made of plastic, for example. On the other hand, in the press molding method, the clay-like mixture is forced into the mold and the mixture in the mold is pressed using a press. The mold used in the press molding method needs to be strong, so it is preferably a metal mold. In the press molding method, the mold is removed from the molded body after pressing using the press.

[0022] Next, the molded body produced in step S12 is dried (step S13). The molded body may be dried naturally, or may be dried by heating using a dryer or by blowing air. In the case of heating and drying, the air in the dryer may be heated to a temperature in the range of 50°C to 150°C, preferably 100°C to 110°C. In the case of slip casting, the molded body is dried with the mold attached, and once dry, the molded body is removed from the mold. The dried molded body is slightly shrunk relative to the inner surface of the mold, so it can be easily removed.

[0023] Next, the molded body dried in step S13 is fired (step S14). Specifically, the dried molded body is placed in a heating furnace, and the temperature inside the heating furnace is maintained at a constant temperature (firing temperature) for a certain period of time (firing time), thereby transforming the molded body into a fired body. The firing temperature is, for example, within the range of 1000°C to 1200°C, preferably within the range of 1050°C to 1150°C, and is, for example, 1100°C. The firing time may be set depending on the size of the molded body, and is, for example, within the range of 1 hour to 3 hours, and is, for example, 2 hours. The manufacturing method of the air diffusion plate 2 has been described above.

[0024] The diffuser plate 2 manufactured under the above conditions has an average bubble diameter of 1 mm or less when gas is sprayed into water, has a pressure resistance of 0.2 MPa or more, and is sized to have a unit area of ​​1 m. 2 Microbubbles can be sprayed into water at a flow rate of 200 L / min or more per minute. In addition, the shrinkage rate during firing is kept to 5% or less based on the molded body before drying, preventing cracks and deformation in the air diffuser plate 2.

[0025] The decision as to whether to use the casting method or the press molding method for manufacturing the air diffuser plate 2 can be made comprehensively, taking into consideration the skill of the worker, the required quality, and the need for mass production. The casting method can produce an air diffuser plate 2 that uniformly emits fine bubbles, but it is more time-consuming to manufacture than the press molding method and is not suitable for mass production. On the other hand, the press molding method is more difficult to produce an air diffuser plate 2 that uniformly emits fine bubbles than the casting method, and the molding molds are expensive, but the kneaded body is easier to handle than a slurry and is therefore more suitable for mass production.

[0026] (Assembling method) A method for assembling the air diffusion device 1 according to the embodiment will be described below with reference to Fig. 4. First, the air diffusion plate 2 is adhered to the case 3 using an adhesive (step S21). Specifically, the adhesive is applied to the step 3d of the case 3, and the bottom surface of the air diffusion plate 2 is pressed against this step 3d. It is preferable to use a highly viscous adhesive, such as an epoxy adhesive, as the adhesive.

[0027] Next, a sealant is used to seal the gap between the air diffusion plate 2 and the case 3 (step S22). Specifically, a syringe is used to pour the sealant into the gap between the air diffusion plate 2 and the case 3 so as to fill it. As the sealant, it is preferable to use a curing agent that has lower viscosity and higher fluidity than an adhesive, such as epoxy resin. The above is the method for assembling the air diffuser 1.

[0028] As described above, the diffuser plate 2 according to the embodiment is made of a porous material containing combustion ash and a binder, has a pair of opposing surfaces, and receives air on one surface in liquid and releases fine bubbles from the other surface. Therefore, it can be manufactured using a simple process using combustion ash, an inexpensive raw material. As a result, the diffuser plate 2 can be manufactured at low cost, and the combustion ash emitted in large quantities from facilities equipped with combustion equipment, such as thermal power plants and steel mills, can be effectively utilized, reducing the cost of disposing of combustion ash and the environmental impact.

[0029] The present invention is not limited to the above-described embodiment, and the following modifications are possible.

[0030] (Variation) In the above embodiment, the diffuser plate 2 is formed in a disk shape, but the present invention is not limited to this. The diffuser plate 2 can be formed in any shape, for example, it may be formed as a rectangular plate. Furthermore, the diffuser plate 2 is merely one example of an air diffuser that has a pair of surfaces located at different positions and receives air on one surface in liquid and emits fine bubbles from the other surface. The air diffuser may also be formed, for example, as a cylindrical air diffuser that receives air on the inner surface and emits fine bubbles from the outer surface.

[0031] In the above embodiment, to prevent cracking during firing, the ratio of binder contained in the raw materials excluding moisture is set to 50 wt% or less, and the component ratios of calcium and iron contained in the combustion ash are each set to 5 wt% or less, but the present invention is not limited to this.In addition to the composition and blending ratio of the raw materials and the components of the combustion ash, other factors such as the particle size of the raw materials can also be considered as factors that cause shrinkage during firing, so the condition may be set such that raw materials with a shrinkage rate of 5% or less during firing are used.

[0032] In the above embodiment, raw materials including combustion ash and clay are mixed, water is added, the mixture is molded using a frame, and the molded body is dried and fired to manufacture the air diffuser plate 2. However, the present invention is not limited to this. For example, a slice molding method may be used in which molding and firing are carried out in the same manner as for making bricks, and the resulting fired block body is then sliced.

[0033] Specifically, the slice molding method involves sequentially kneading, extruding, and cutting the raw materials to produce a block-shaped molded body, which is then dried and fired to produce a block-shaped fired body having a shape similar to a brick. The extruded mixture can be cut into individual blocks with, for example, a piano wire to produce a block-shaped molded body. Next, the resulting block-shaped fired body is sliced ​​to the desired thickness using a cutting means such as a diamond cutter. While the slice molding method makes it difficult to produce the air diffuser plate 2 in any desired shape, it is suitable for mass production and allows for easy quality control.

[0034] The above-described embodiments are merely examples, and the present invention is not limited to these. Various embodiments are possible within the scope of the invention as set forth in the claims. The components described in the embodiments and modifications can be freely combined. Furthermore, inventions equivalent to the inventions set forth in the claims are also included in the present invention.

[0035] The present invention will be specifically described below with reference to examples, although the present invention is not limited to these examples.

[0036] Example 1 In Example 1, various test specimens were prepared using coal ash and clay as raw materials, varying the type of coal from which the coal ash was made, the mixing ratio of the raw materials, and the firing conditions. The test specimens were prepared using a press molding method. Then, the test specimens were placed in a case in water, and air bubbles were generated to verify whether the test specimens functioned as air diffusers.

[0037] The coal ash used was fly ash (FA) separated from the exhaust gases of coal-fired power plants. Three types of FA were used as raw materials: 100% coal ash A, 70% coal ash B, 30% coal ash C, and 80% coal ash D and 20% coal ash E. Coal ashes A to E each have a different component ratio. For example, 70% coal ash B and 30% coal ash C represent a mixture of 70% coal ash B and 30% coal ash C by weight. The raw material mixture ratios were 80%:20% FA:clay, 70%:30%, and 50%:50% FA:clay. All specimens were 100 mm square and 10 mm thick. The firing temperatures were 1000°C, 1100°C, and 1200°C, and the firing time was 2 hours.

[0038] As a result, as shown in Figures 5 to 7, when the molded bodies were fired at firing temperatures of 1000°C, 1100°C, and 1200°C, fired bodies were obtained and it was confirmed that they functioned as air diffuser plates in water. Specifically, when the firing temperature was 1100°C, good test specimens were obtained in terms of strength, shape, and function. However, when the firing temperature was 1200°C, the test specimens were prone to distortion, and depending on the coal type, some parts melted and peeled off. Furthermore, when the firing temperature was less than 1000°C, the test specimens were not strong enough to withstand the gas pressure when bubbles were generated, resulting in cracks and peeling. From the above, it can be seen that a firing temperature of 1100°C is preferable. It can also be seen that the coal type and the blending ratio of the raw materials have almost no effect on the strength and performance of the air diffuser plate.

[0039] Example 2 In Example 2, the relationship between the composition and blending ratio of the raw materials and cracking of the fired body was investigated. First, the raw materials were mixed under the conditions shown in Samples 1 to 4 in Figure 8, molded using a press molding method, dried, and fired to create eight test specimens for each condition. Combustion ash A in Figure 8 is fly ash. The weight of the raw materials excluding water was 500 g for all test specimens. The diameter of the test specimens before firing was 165 mm and the thickness was approximately 15 mm. The pressing pressure applied to the test specimens before firing was 5 tons. The drying conditions were natural drying or heat drying at a temperature of 105°C. Based on the results of Example 1, the firing temperature was set to 1100°C and the firing time to 2 hours.

[0040] As a result, as shown in Figure 9, fired bodies were obtained for all of Samples 1 to 4. Sample 1 was made by simply kneading clay with water, which resulted in significant shrinkage and the occurrence of numerous fine cracks. For Samples 2 and 3, seven out of eight plates each had no cracks, and the remaining plate only had a small crack at the edge. Sample 4 did not contain clay and had low toughness, which is likely why large cracks occurred during firing. From the above, it can be seen that if shrinkage during firing is large, the fired body is prone to cracks and deformation, and that a combination of coal ash and clay is an ideal raw material for air diffuser plates.

[0041] Example 3 In Example 3, the relationship between the component ratio of coal ash and the shrinkage rate during firing was examined. Specifically, 1% CMC was added to each of combustion ashes A and B having the component ratios shown in Figure 10, and then water was added and kneaded, and test specimens were prepared by press molding, and the shrinkage rate during firing was measured. Combustion ashes A and B in Figure 10 are fly ashes derived from different coal types. The other conditions were the same as in Example 2. For comparison, a similar experiment was also conducted on clay having the component ratio shown in Figure 10. Only water was added to the clay and kneaded, and test specimens were prepared by press molding.

[0042] As a result, the shrinkage rate of the test specimen using combustion ash A was 1.8%, while the shrinkage rates of the test specimens using clay and combustion ash B were 6.1% and 7.3%, respectively. The test specimen using combustion ash A showed almost no deformation, whereas the test specimens using clay and combustion ash B had large shrinkage rates and therefore showed cracks and warping, as shown in Figure 11. From the above, it can be understood that it is preferable to use combustion ash with a low calcium and iron content as the raw material for the air diffuser plate.

[0043] Example 4 In Example 4, we investigated whether the casting method could be used to manufacture diffuser plates. Specifically, combustion ash and clay were first mixed and water was added to create a slurry. The combustion ash was fly ash. Considering the results of Example 2, the raw material blend ratio was 80% combustion ash and 20% clay, with a total weight of 1,000 g. The amount of water added was 40%. Next, as shown in Figure 12, the slurry was poured into a mold, the surface shape was adjusted, and then it was heated and dried at 105 °C for 24 hours using a dryer. The mold shape was 165 mm in diameter and approximately 15 to 34 mm thick. Next, after drying was completed, the mold was removed and fired at 1,100 °C for 2 hours, as in Example 2. As a result, it was confirmed that a fired body of combustion ash and clay could be obtained using the casting method, as shown in Figure 12.

[0044] Example 5 In Example 5, we verified whether the slicing method could be used to manufacture diffuser plates. Specifically, combustion ash and clay were mixed, and water was added to create a kneaded mixture. The mixture was then kneaded and fired in a brick factory production line using the same method as for bricks. The combustion ash was fly ash. The raw material composition was 50% combustion ash and 50% clay. As a result, a fired block was obtained, as shown in Figure 13. The cross section of this block was rectangular, measuring 100 mm x 100 mm. Using a diamond cutter, it was possible to slice it to a thickness of 15 mm, which is the appropriate thickness for a diffuser plate. We confirmed that this sliced ​​diffuser plate was also capable of emitting fine bubbles in water.

[0045] Example 6 In Example 6, the average bubble diameter of bubbles generated by the diffuser plate was measured. Specifically, air was sent to the diffuser plate to which the case was attached to generate bubbles, and the bubbles in the water were visualized using a backlight method and photographed with a high-speed camera. The photographed images were then analyzed to calculate the bubble diameter. The Sauter mean value was calculated from the calculated bubble diameters to obtain the average bubble diameter. The test specimens were three types: a 15 mm thick diffuser plate made by press molding, and 27 mm and 34 mm thick diffuser plates made by casting. All diffuser plates were disc-shaped.

[0046] As a result, as shown in Figure 14, fine bubbles with an average bubble diameter of 1 mm or less were generated in all test specimens. The air diffuser plate made by the casting method had a smaller average bubble diameter than the air diffuser plate made by the press molding method. Furthermore, while the air diffuser plate made by the casting method generated fine bubbles uniformly, the air diffuser plate made by the press molding method had some areas with fewer bubbles in the center, and there was variation in the generation of bubbles. This is thought to be because the press molding method is prone to unevenness when filling the mold with raw materials and applying pressure.

[0047] Example 7 In Example 7, it was verified whether a diffuser plate could be used to neutralize wastewater from a concrete factory. In the experimental equipment, as shown in Figure 15, 20 L of concrete factory wastewater with a pH of 12.42 was stored in a water tank, and carbon dioxide gas was supplied to this concrete factory wastewater, and the change in pH value over time was measured. Carbon dioxide gas was supplied from a liquefied gas cylinder (CO2 99.5%), and the gas flow rate was 1.0 L / min. The test specimens were a 34 mm thick diffuser plate made by the casting method, and commercially available diffuser plates A and B. Both had an area of ​​60 cm. 2 Commercially available air diffuser plate A is an air diffuser plate that is actually used in neutralization treatment equipment, and commercially available air diffuser plate B is an air diffuser plate that is commercially available as an air stone for fish breeding.

[0048] As a result, as shown in Figure 16, the diffuser plate made by the casting method had a neutralization efficiency equivalent to that of commercial diffuser plate A, and was more efficient than commercial diffuser plate B. Furthermore, when we verified whether neutralization could be carried out by replacing carbon dioxide gas containing 99.5% CO2 with exhaust gas collected from a thermal power plant (component ratio: CO2 10%, O2 10%, N2 80%), we were similarly successful in lowering the pH of concrete wastewater to 7. [Explanation of symbols]

[0049] 1 Air diffuser 2. Air diffuser 3 cases

Claims

1. The diffuser is made of a porous body that is a fired body of a molded body containing combustion ash and a binder, and converts the received gas into fine bubbles by passing the gas through the diffuser and releases the bubbles into the liquid. The diffuser has a pressure resistance of 0.2 MPa or more, and when pressurized gas is received from the outside, the diffuser is ２ The nozzle is configured to be able to emit fine bubbles into the liquid at a flow rate of 200 L / min or more per nozzle. The binder includes at least one of clay and a cellulose-based water-soluble polymer. Aeration body.

2. The calcium and iron contained in the combustion ash are each 5% wt or less. The air diffuser according to claim 1.

3. The binder is clay. The air diffuser according to claim 1 or 2.

4. The ratio of the combustion ash in the raw material of the diffuser is 50 wt% or more, and the ratio of the binder is 50 wt% or less. The air diffuser according to claim 1 or 2.

5. 3. The method for manufacturing the gas diffuser according to claim 1 or 2, a mixing step of mixing the combustion ash, the binder, and water; a molding step of molding the mixture obtained in the mixing step; a drying step of drying the molded body molded in the molding step; a firing step of firing the dried molded body; A method for manufacturing an air diffuser comprising the steps of:

6. In the firing step, the dried molded body is fired at a constant temperature set within a range of 1000°C to 1200°C. The method for manufacturing the air diffuser according to claim 5.

7. In the mixing step, a slurry containing the combustion ash, the binder, and the water is generated, In the molding step, the produced slurry is poured into a mold. The method for manufacturing the air diffuser according to claim 5.

8. In the mixing step, a kneaded material containing the combustion ash, the binder, and the water is generated, In the molding step, the produced kneaded material is pressed into a mold and pressurized. The method for manufacturing the air diffuser according to claim 5.

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