JP5088296B2 - Air diffuser - Google Patents

Description

  The present invention relates to an air diffuser capable of removing dirt components adhering to an air diffuser surface of an air diffuser plate and supplying oxygen stably for a long period of time.

  In order to remove nitrogen compounds and carbon compounds in sewage at a sewage treatment facility, an activated sludge method utilizing decomposition and adsorption by microorganisms is used. In order for the microorganisms in the activated sludge to be active, it is necessary to give oxygen to the microorganisms. The air diffuser is an apparatus that is installed at the bottom of an aeration tank of a sewage treatment facility and supplies oxygen into water. There are two types of diffusers: a diffuser with a film diffuser surface (Patent Document 1) and a diffuser with a metal thin plate type diffuser surface (Patent Document 2). The thin metal plate type air diffuser has less pressure loss due to air diffused, and is excellent in durability and ease of maintenance and inspection.

  When the aeration apparatus continues aeration operation for a long period of time, the dirt component adheres to the inside and the surface of the fine holes of the film or the metal thin plate, thereby causing clogging. Most of the soil components that cause clogging are slimes formed by microorganisms, which block the air holes. The slime has a strong adhesive force, and the slime cannot be peeled off even if the gas pressure is increased.

  In the membrane-type air diffuser, a method is disclosed in which the membrane is elongated or contracted by the air-feeding operation of the air diffuser to remove the microorganism-derived slime attached to the inside and the surface of the micropores of the membrane (Patent Document 3). ).

  However, in the thin metal plate type air diffuser, since the air diffused surface is a rigid body having no elasticity, the above-described clogging prevention treatment cannot be performed. At present, when clogging occurs due to the growth of microorganisms in a thin metal plate type diffuser, the diffuser plate must be cleaned by lifting the diffuser onto the water surface. Management requires a lot of labor and expense.

In both the membrane type and the thin metal plate type, it is necessary to reduce the pore diameter of the diffuser surface in order to increase the oxygen transfer efficiency. However, the smaller the pore diameter, the more likely clogging occurs. Air diffusers that are prone to clogging must be lifted above the surface of the water and frequently cleaned.
JP 2003-320388 A JP 2006-61817 A JP 2004-313938 A

  Thus, the conventional diffuser has not provided a sufficient solution to the clogging problem. An object of the present invention is to provide an air diffuser that has micropores that can achieve high oxygen transfer efficiency, is less likely to be clogged, and can be operated stably for a long period of time.

In order to solve the above problems, the inventor injects water or cleaning water such as a chemical solution into the air supply pipe for air diffusion, and supplies the air to the air diffuser plate side with the pressure air for air diffusion. We considered to automatically clean the air plate regularly. As a specific means for realizing this, it has been considered to provide an intubation tube in which one end communicates with the air diffuser plate and the other end is inserted into the air supply pipe for air diffusion.
Moreover, in order to effectively perform the automatic cleaning of the diffuser plate and to prevent clogging even if it is operated for a long period of time, the micropores provided in the diffuser plate were also examined, and the optimum dimensions were found.
The present invention has been made on the basis of such knowledge, and specifically has the following configuration.

(1) An air diffuser according to the present invention includes an air diffuser arranged in an aeration tank and receiving air pressure from an air diffuser supply pipe to release bubbles from a slit, and the air supply for the air diffuser. Blow water supply means for overcoming the air pressure in the air supply pipe for air diffusion into the pipe and supplying blow water;
From the diffuser plate, the diffuser plate is connected to the diffuser plate with an upper end communicated with the diffuser plate and a lower end inserted into the diffuser air supply pipe and supplied to the diffuser air supply pipe. The inner tube to be discharged is integrally formed, the slit formed in the diffuser plate is rectangular, and the length of the short side is set to 0.03 mm to 0.15 mm. It is what.
Note that the lower end portion of the intubation tube may have an inclined suction surface. Furthermore, a vent hole may be provided in the tube wall of the internal intubation.

(2) Further, in the above (1), the length of the long side of the slit is set to 0.1 mm to 1.5 mm.

  In the air diffuser of the present invention, a rectangular slit is formed in the air diffuser plate, the length of the short side is set to 0.03 mm to 0.15 mm, the upper end is communicated with the diffuser plate side, and the lower end is The provision of the internal intubation inserted in the air supply piping for the air diffusion makes it possible to effectively perform periodic water blowing, thereby clogging the air diffusion plate while maintaining high oxygen transfer efficiency. Can be prevented over a long period of time.

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

1. Air diffuser FIG. 1 is a schematic diagram showing an air diffuser according to the present embodiment. The air diffuser 1 according to the present embodiment includes a gas supply means 2, an air supply pipe 3 (header pipe) for introducing air supplied from the gas supply means 2 to an air diffuser plate 4, and an air supply for air diffusion. A diffuser plate 4 that receives supply of pressurized air from the air pipe 3 and releases fine bubbles, and an intubation tube 7 having an upper end communicating with the air diffuser plate 4 and a lower end inserted into the air supply pipe 3 for aeration. And a blow water supply means 5 for supplying blow water to the diffuser air supply pipe 3 via the blow water supply pipe 14.
An open / close valve 15 is provided in the air supply pipe 3 for diffusion, and an open / close valve 16 is provided in the blow water supply pipe 14.
Hereinafter, the main configuration of the air diffuser 1 will be described in detail.

<Air diffuser>
The diffuser plate 4 may be any form of diffuser plate such as a membrane type or a thin metal plate type. For example, when the diffuser plate 4 is a thin metal plate type, a thin metal plate having slits formed by machining is used. The air supplied from the gas supply means 2 is supplied to the diffuser plate 4 from the diffuser supply pipe 3 through the inner tube 7, and is released from a plurality of slits scattered on the diffuser surface of the diffuser plate 4. The

  FIG. 2 is a plan view of the diffuser plate 4, and FIG. 3 is an enlarged view showing an A portion surrounded by a circle in FIG. As shown in FIG. 3, the diffuser plate 4 is provided with a large number of rectangular slits 4a. When the length of the long side is a and the length of the short side is b, a is 0.1 mm. -1.5 mm and b are set to be 0.03 mm to 0.15 mm. The reason why the lengths of the short side and the long side of the slit are set in this way is as follows.

When the shape of the fine holes provided in the diffuser plate 4 is a rectangular slit, the obstruction suppressing effect that suppresses the obstruction of the slit by removing dirt attached to the slit with blow water depends on the length of the short side of the slit. The longer the length of the short side is, the higher the blocking effect becomes.
On the other hand, when the length of the short side of the slit is increased, the bubble diameter is increased and the oxygen transfer efficiency is lowered.
Therefore, the length of the short side of the slit provided in the diffuser plate 4 is required to have a high blocking suppression effect and high oxygen transfer efficiency.
Therefore, the length of the short side of the slit for obtaining a high oxygen transfer efficiency (25% or more) and suppressing the increase in pressure loss due to blockage (the amount of increase in pressure loss after 100 days of ventilation is 100 mmAq or less) will be described later. As a result of the experiment shown in Fig. 4, it was found that the length of the short side should be 0.03 mm to 0.15 mm. Moreover, about the length of the long side of a slit, since this will have a bad influence on oxygen transfer efficiency if it is too long, it set to 0.1 mm-1.5 mm as a range which does not have influence.

<Intubation>
Since the air diffuser 1 according to this embodiment includes the inner intubation tube 7, water can be supplied to the air diffuser holes without filling the air diffuser air supply pipe 3 with water. Therefore, a large amount of water is not required. In particular, when an aqueous solution containing an antibacterial substance is supplied, microorganisms can be efficiently removed in a short time with a small amount of the antibacterial substance. As a result, it is not necessary to lift the air diffuser above the water surface and clean it frequently, and the air diffuser can be operated stably for a long time under the water surface.

  In addition, when there is no inner intubation 7 and it is going to supply the water for washing | cleaning the diffuser board 4, not only the air supply piping 3 for aeration needs to be filled as mentioned above but it is also filled with water. It is necessary to devise in order to drain the water. If there is no means for draining water, water remains in the air supply piping for the air diffuser to which the air diffuser plate 4 is attached, the pipe line becomes thin, and appropriate air diffusion cannot be performed. .

  FIG. 4 is a partial cross-sectional view showing an example of the internal intubation 7. The inner insertion tube 7 has an upper end communicating with the air diffusion plate 4, a lower end inserted into the air supply pipe 3 for diffusion, an inclined suction surface 8 at the lower end, and a vent hole 9 in the tube wall. have. However, the vent hole 9 provided in the inner intubation tube 7 is not essential, and the vent hole 9 may not be provided. As described later, the mode of pumping the blow water to the inner intubation tube 7 differs depending on whether the vent hole 9 is present or not. .

  The internal intubation 7 is a supply path to the air diffusion plate 4 and has a function of discharging the supplied blow water from the diffusion plate 4 during the water blowing process.

The inner intubation 7 may be formed integrally with the air supply pipe 3 for diffusing or may be a separate member that can be attached and detached. When it is set as another member which can be attached or detached, the inner intubation tube 7 can be inserted and fixed in the insertion port previously provided in the air supply piping 3 for aeration. There is no restriction | limiting in particular in the fixing method of the intubation tube 7, All fixing methods are included. For example, the fixing tightening member 10 is pre-welded to the side surface of the inner intubation tube 7 and the mounting bracket 11 is pre-welded to the diffuser air supply piping side, so that the inner intubation tube 7 is screwed and the air supply piping for air diffusion is installed. 3 can be fixed.
Similarly, the diffuser plate 4 can be formed integrally with the inner intubation tube 7 or can be attached and detached. Moreover, there is no restriction | limiting in particular in the material of an intubation tube, Preferably, it forms from metals, such as plastic or stainless steel, titanium.

The lower end portion of the inner intubation 7 has a suction surface 8. A plurality of diffuser plates 4 are installed in the diffuser supply pipe 3, but the diffuser supply pipe 3 is not necessarily installed horizontally, and the lower end of the intubation pipe 7 is the water surface. May not be arranged at the same height. As shown in FIG. 5, when the suction surface 8 at the lower end of the intubation tube is not inclined, the lower end portion is sucked up only from the inner tube 7 that is in contact with the water surface or under the water surface (expressed as “sucking up” in this specification). In some cases, “push-up” may be included), so that the blow water is not uniformly supplied to all the diffuser plates 4, and clogging is caused by some diffuser plates to which blow water is not supplied. There is a risk of progress.
On the other hand, as shown in FIG. 6, when the suction surface 8 at the lower end of the intubation tube is inclined, the blow water can be sucked up if the water surface is between the upper end and the lower end of the suction surface 8. Even when the lower end of the intubation is arranged up and down, suction from all the inner intubations is possible within a certain range, and uniform blow to the diffuser plate 4 is possible. Therefore, when the suction surface 8 is inclined, the allowable range of the installation accuracy in the horizontal direction of the air supply pipe 3 for air diffusion becomes large.

  In addition, as shown in FIG. 6, when the water level is between the upper end and the lower end of the suction surface 8, the air-water mixed phase is blown at a high blow speed. However, as shown in the right diagram of FIG. When it becomes higher than 8, since only water is sucked up, it becomes a water extrusion blow in which air does not mix. On the other hand, when the vent hole 9 is provided in the tube wall of the inner intubation tube 7 as shown in the left diagram of FIG. 7, air enters from the vent hole 9 even when the water level is higher than the suction surface 8. A high-speed air-water mixed phase can be blown.

There is no restriction | limiting in particular in the shape and magnitude | size of the vent hole 9, It can be set as arbitrary shapes and magnitude | sizes. For example, when the total length of the inner intubation tube 7 is 200 mm and the inner diameter of the inner intubation tube 7 is 13 mm, the vent hole 9 can have a circular shape with a diameter of 1 mm to 10 mm, preferably 2 mm to 7 mm. The position of the vent hole 9 is not particularly limited and can be set to an arbitrary position. For example, when an intubation tube having a total length of 200 mm and an inner diameter of 13 mm is mounted in an air supply pipe for air diffusion with an inner diameter of 80 mm, and the lower end of the inner tube is in contact with the inner bottom portion of the air supply pipe for air diffusion, It can be provided at a position of 10 mm to 75 mm, preferably 30 to 70 mm from the lower end of the intubation tube.
Further, since the inside of the air supply piping for air diffusion is pressurized, the position of the vent hole 9 may be on the front side or the back side with respect to the direction of water blow and gas flow.

The lower end of the inclined suction surface 8 is located in the vicinity of the inner bottom of the air supply pipe 3 for diffusing, so that even if the water level is low, the blow water can be surely sucked into the inner tube 7. The lower end of the inclined suction surface 8 is preferably 0 to 10 mm above the inner bottom of the air supply pipe 3 for air diffusion.
Although there is no particular limitation on the inclination angle θ of the inclined suction surface 8 with respect to the vertical direction, since the intubation tube 7 is also an air supply path, the inclination angle θ is such that air can be sufficiently supplied into the intubation tube 7. It is preferable. The inclination angle θ can be, for example, 10 to 85 degrees, preferably 30 to 80 degrees.

<Blow water supply means>
The blow water supply means 5 is a device for supplying blow water to the air supply pipe 3 for air diffusion via the blow water supply pipe 14, for overcoming the air pressure of the air supply pipe 3 for air diffusion. The air supply pipe 3 can be supplied. As the blow water supply means 5, there is, for example, a water storage tank provided with a water pump.
The blow water supplied from the blow water supply means 5 flows into the air supply pipe 3 through the blow water supply pipe 14 and the pressure in the air supply pipe 3 becomes higher than a predetermined pressure. Sometimes, air is supplied from the air supply pipe 3 through the inner intubation 7 to the air diffuser plate 4 and is released from a plurality of air diffuser holes scattered on the air diffuser surface of the air diffuser plate 4 like air.

2. Operation Method of Air Diffuser A normal air diffuser is operated by opening the on-off valve 15 and closing the on-off valve 16.
Further, at the time of the blow operation in which the air diffuser plate 4 is blown with water, the on-off valve 16 is opened and the blow water is supplied to the air diffuser supply pipe 3 so that the air diffused and the blow water are passed through the inner tube 7. And supply to the diffuser plate 4.
The air diffuser 1 according to the present invention removes microorganisms adhering to the air diffuser without pulling up the air diffuser onto the water surface by periodically supplying blow water from the blow water supply means 5 to the air diffuser plate 4. can do. In addition, although there is no restriction | limiting in particular in the supply frequency of blow water, Preferably blow water is supplied in the air supply piping 3 for aeration every several hours to several days.

As described above, the air diffuser 1 according to the present embodiment includes the inner tube 7 and can supply blow water to the air diffuser plate 4 without filling the water, so that an air supply passage is provided. Is always secured. Accordingly, it is possible to continuously operate the air diffuser 1 while supplying blow water periodically during the air supply and removing the microorganisms adhering to the air diffuser holes of the air diffuser plate 4 with the blow water.
Moreover, in this Embodiment, since the micropore formed in a diffuser board was made into the rectangular-shaped slit, and the length of the short side was set to 0.03 mm-0.15 mm, the diffuser board of a water blow is used. High clogging prevention effect and high oxygen transfer efficiency.

  In the above embodiment, the blow water is not particularly limited. However, the use of blow water containing a component having an effect of killing microorganisms can effectively suppress the growth of microorganisms. . The component having an effect of killing microorganisms is not particularly limited, but for example, an antibacterial substance or an oxidizing substance, more specifically, sodium hypochlorite, inverse soap, acid, alkali, ozone, or chlorine dioxide And alkali metal carbonates.

  First, in order to verify the effect of water blow by the intubation tube 7, a diffuser plate with a relatively short short side (narrow width) was installed in the aeration tank, and water was blown under the following conditions.

Air diffuser material: SUS316L
Hole shape: length 1.45mm, short side (width) 0.04mm
Opening ratio: about 0.5%
Ventilation rate: 30m3 / m2 / hr
Blow water: Sodium hypochlorite solution (concentration: 100 ppm)
Blow water volume: 500 ml / time Water blow frequency: 1 time / day An example in which no water blow was performed was used as a comparative example.

  The graph of FIG. 8 shows the change over time in the amount of increase in pressure loss (mmAq) in the example (Example) with and without water blow (Comparative Example).

  As is clear from the graph of FIG. 8, by periodically carrying out the water blow, it is possible to effectively suppress an increase in the pressure loss of the air diffuser even in the air diffused operation over a long period of time, and to achieve a high oxygen transfer efficiency. Could be maintained.

Next, in order to confirm the influence of the change in the short side length of the slit, an aeration plate having a different length of the short side of the slit was installed in the aeration tank, and a continuous aeration operation was performed under the following conditions.
Air diffuser plate material: SUS316L
Long slit length: 0.5mm
Ventilation rate: 30m ³ / m ² / hr
Blow water: Sodium hypochlorite solution (concentration: 20 ppm)
Blow water volume: 500ml / time Water blow frequency: 2 times / day

Table 1 shows the oxygen transfer efficiency (initial stage of aeration) and the amount of pressure loss increase 100 days after the start of aeration.

As can be seen from Table 1, when the slit short side is 0.15 mm or less, a high oxygen transfer efficiency of 25% or more can be obtained. On the other hand, the longer the slit short side is, the easier it is to remove clogging substances by water blow, the amount of increase in pressure loss after 100 days becomes lower, and the amount of increase in pressure loss after 100 days becomes 100 mmAq or less when the slit short side is 0.03 mm or more. .
From this, if the length of the short side of the slit is set in the range of 0.03 mm to 0.15 mm, a high oxygen transfer efficiency of 25% or more can be obtained and the removal of the blocking substance by water blow can be effectively performed. It was confirmed.
In addition, if the length of the short side of the slit is set in the range of 0.08 mm to 0.12 mm, an extremely high oxygen transfer efficiency of 30% or more can be obtained, and the pressure loss increase after 100 days is 70 mmAq or less. The removal of the occlusive substance by the can be performed more effectively, which is preferable.

It is a mimetic diagram of an air diffuser concerning one embodiment of the present invention. It is a top view of the diffuser plate which concerns on one embodiment of this invention. It is an enlarged view which expands and shows a part of FIG. It is sectional drawing of the intubation which concerns on one embodiment of this invention. It is a figure which shows the one aspect | mode of the intubation tube which concerns on one embodiment of this invention, and is a schematic diagram in case the suction surface is not inclined. It is a figure which shows the other aspect of the intubation tube which concerns on one embodiment of this invention, and is a schematic diagram in case the suction surface inclines. It is explanatory drawing of the intubation in one embodiment of this invention, and is a schematic diagram which shows the effect of the vent provided in the intubation. It is a graph which shows a time-dependent change of the pressure loss increase amount of an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air diffuser 2 Gas supply means 3 Air supply piping for air diffusion 4 Air diffuser plate 4a Slit 5 Blow water supply means 7 Inner intubation 7a Valve seat 8 Suction surface 9 Vent hole 10 Fixing member 11 Mounting bracket 12 Aeration tank 14 Blow water supply pipe 15, 16 On-off valve θ Inclination angle

Claims (2)

A diffuser plate that is arranged in the aeration tank and receives pressure air from the diffuser air supply pipe to release bubbles from the slit, and the air pressure in the diffuser air supply pipe is converted into the air diffuser air supply pipe. A blow water supply means for overcoming and supplying blow water;
From the diffuser plate, the diffuser plate is connected to the diffuser plate with an upper end communicated with the diffuser plate and a lower end inserted into the diffuser air supply pipe and supplied to the diffuser air supply pipe. The inner tube to be discharged is integrally formed, the slit formed in the diffuser plate is rectangular, and the length of the short side is set to 0.03 mm to 0.15 mm. Air diffuser. The length of the long side of a slit is set to 0.1 mm-1.5 mm, The aeration apparatus of Claim 1 characterized by the above-mentioned.

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