JP4987811B2 - Aeration stirrer - Google Patents

Description

  The present invention relates to an aeration stirrer for aeration and agitation of sewage and activated sludge mainly composed of microorganisms in a wastewater treatment facility for treating sewage or sewage.

  In a wastewater treatment facility such as a sewage treatment plant, when treating sewage or sewage that has flowed in, the sewage or activated sludge mainly composed of sewage and microorganisms is mixed and stirred in a water tank, and air is supplied to the water tank, that is, aeration. By doing so, activated sludge microorganisms use oxygen in the air to decompose sewage or pollutants in the sewage.

In recent years, there are many aeration methods in which air is supplied into the water tank by installing an air diffuser near the bottom of the water tank and introducing compressed air into the air diffuser from a blower provided outside.
In this method, the air discharged from the air diffuser is made into fine bubbles of 1 millimeter or less, thereby increasing the surface area of the bubbles, thereby improving the efficiency of oxygen transfer to the liquid phase.

However, in this air diffuser, a large-capacity blower is required to introduce compressed air to the vicinity of the bottom of the water tank, and a large amount of power is required for its operation.
In addition, in order to treat sewage well in the water tank, it is necessary to distribute the air released from the air diffuser throughout the water tank, that is, to properly mix and agitate the water tank. However, there is a problem that a large amount of power is required, such as providing an auxiliary stirring device or increasing the amount of compressed air to be introduced.

  An object of the present invention is to provide an aeration stirrer that can efficiently perform aeration and agitation with a small amount of power in view of the problems of the conventional aeration and agitation methods.

In order to achieve the above object, the aeration stirrer of the present invention is provided with an upper stirring blade for generating an upward flow at the upper portion of the rotating shaft and a lower stirring blade for generating a downward flow at the lower portion of the rotating shaft. provided a tubular body having a water inlet between the stirring blade covering the periphery of the rotating shaft in a vertical direction, is provided immediately below the balloon portion of the downward flow of the lower cylindrical body of the lower part stirring blades, release bubbles Air bubbles provided directly above the ring-shaped lower tube and the upward flow blowing portion on the upper side of the upper stirring blade, with the pores to be formed on the inner peripheral side having the same diameter as the lower opening of the tube An air diffuser for supplying air bubbles to a ring-shaped upper cylindrical tube provided with an inner peripheral side in which pores for discharging air are formed to have substantially the same diameter as the upper opening of the cylindrical body is provided.

In this case, the air diffuser includes a microbubble generator, and water containing bubbles generated by the microbubble generator can be supplied to the lower tube and the upper tube .

Further, with the rotary shaft hollow form, subjected feed water containing bubbles from an air diffuser inside the rotary shaft, to release toward the balloon portion of the downward flow of the cylindrical body from the lower opening of the rotary shaft it can be so.

According to the aeration agitator of the present invention, dispersion of bubbles from the air apparatus can be miniaturized by the strong shearing action by the lower agitating blade and the upper stirring blades, thereby, increase the diameter of the pores for supplying air bubbles air The exit resistance can be reduced.
In addition, the refined bubbles stay in the lower and upper parts of the water tank for a long time along with the descending and rising water flow by the aeration stirrer, and the required oxygen dissolution rate can be obtained even if the amount of air supplied is small. The power of the blower of the diffuser can be greatly reduced by reducing the supply amount.
In addition, the water flow of the lower stirring blade can ensure a sufficient bottom portion flow rate and homogeneous stirring in the tank to prevent sludge accumulation.

In particular , it is possible to make the bubbles finer by the shear flow generated inside the tube and to have a structure that does not become an obstacle to the water flow of the stirring blade.

Further, by providing the pores on the inner peripheral side of the cylindrical tube, is dense pores, by utilizing a negative pressure caused by water flow stirring blades can be reduced power blowing air.

In addition, the air diffuser includes a microbubble generator, and water containing bubbles generated by the microbubble generator is supplied to the lower tube and the upper tube , so that the microbubbles can be removed from the ground side. In addition, the power of the blower of the air diffuser can be greatly reduced, and the refined bubbles can be retained in the water tank for a long time together with the water flow of the stirring blade, so that the necessary oxygen dissolution rate can be obtained even with a small amount of air.

Further, with the rotary shaft hollow form, subjected feed water containing bubbles from an air diffuser inside the rotary shaft, to release toward the balloon portion of the downward flow of the cylindrical body from the lower opening of the rotary shaft By doing so, fine bubbles can be supplied to the lower side of the lower stirring blade through the rotating shaft.

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

As shown in FIG. 1, the aeration stirrer of the present invention is provided with an upper stirring blade 2 that generates an upward flow at the upper portion of the rotating shaft 1 and a lower stirring blade 3 that generates a downward flow at the lower portion of the rotating shaft 1. ing.
And the cylinder 4 which has the water intake 41 between the upper and lower stirring blades 2 and 3 and covers the periphery of the rotating shaft 1 is provided, and the upper and lower portions of the lower stirring blade 3 and the upper stirring blade 2 are vertically An air diffuser 5 for supplying air bubbles from the cylindrical tubes 51 and 52 is provided.

In the aeration stirrer of the present invention, the amount of air blown into the water tank is greatly reduced, and the power of the blower 53 required for the blowing is greatly reduced.
On the other hand, a small amount of air stays in the water tank for a long time, and in order to secure the bottom flow velocity, the power of the stirring blades 2 and 3 for generating forced convection that makes the trajectory of the water flow long is added. However, since the stirring blades 2 and 3 are highly efficient with a large flow rate of blowing with respect to the required power, little additional power is required.
Despite reducing the amount of air blown into the sewage in the aquarium (such as activated sludge mixture), the following is done to keep the oxygen dissolution rate in the sewage constant.

(1) By making the bubble diameter retained in the sewage minute and reducing the buoyancy of the bubbles, the bubbles are guided to the water flow generated by the stirring blades 2 and 3 and the length of the water tank along with the water flow until it rises to the water surface. Move distance.

(2) In general, it is known that even if the pores for releasing bubbles are made smaller, the bubbles are not made smaller, pressure loss increases, and required power increases.
In order to prevent this, the bubble diameters blown out from the upper and lower cylindrical tubes 51 and 52 are not necessarily fine immediately after discharge, but once the large bubbles are generated from the large pores, the bubbles are mixed with the stirring blade 2. 3 due to the strong shearing action of 3.

(3) Since the cross-sections of the upper and lower cylindrical tubes 51 and 52 with the pores are circular and the pores are inside thereof, the bubbles blown out from the pores move so as to slide on the surface of the circular cross-section, Are refined by a shear flow generated inside the cylindrical tubes 51 and 52.

(4) The upper and lower cylindrical pipes 51 and 52 with pores are formed in a ring shape having substantially the same inner diameter as the water flow blowing part of the cylindrical body 4 and do not become an obstacle to the water flow.

(5) In order to retain fine bubbles at the bottom of the water tank for a long time, a double flow of an upward flow and a downward flow is generated.
(6) The flow rate ratio between the upward flow and the downward flow is from 3: 7 to 7: 3, and about 5: 5 is particularly suitable for extending the residence time of bubbles by the downward flow of water.

(7) It is known that the supply position of bubbles suitable for extending the residence time is directly below the downward flow blowing portion, and the lower cylindrical tube 52 is disposed at this position.

(8) Since the area in which the fine bubbles in the downward flow mainly stay is the lower half of the water tank, in order to make the fine bubbles stay in the upper half, pores are separately provided on the upward flow blowing portion. An upper cylindrical tube 51 is arranged to diffuse bubbles in the upper part of the water tank.
In this case, in order to secure the bubble generation area, the upper and lower cylindrical tubes 51 and 52 are formed in a ring shape having substantially the same inner diameter as the water flow blowing portion of the cylindrical body 4 and do not become an obstacle to the water flow.

FIG. 1 shows a first embodiment of the aeration stirrer of the present invention.
This aeration stirrer is provided with an upper stirring blade 2 that generates an upward flow at the upper part of a rotating shaft 1 that is rotated by an electric motor 11 and a lower stirring blade 3 that generates a downward flow at the lower part of the rotating shaft 1. A cylindrical body 4 having a water intake 41 between the stirring blades 2 and 3 and covering the periphery of the rotary shaft 1 is provided.
And the diffuser 5 which supplies a bubble to the lower side of the lower stirring blade 3 and the upper side of the upper stirring blade 2 is provided.

The air diffuser 5 is arranged in the upper and lower cylinders by blowing air (oxygen) from a blower 53 through a conduit 54 to a lower cylindrical pipe 52 and an upper cylindrical pipe 51 which are installed in a water tank and have pores on the inside. Air bubbles are discharged from the tubes 51 and 52.
The released bubbles are refined by the lower water flow S1 or the upper water flow S2 generated by the upper stirring blade 2 or the lower stirring blade 3.
The lower water flow S1 becomes more turbulent, particularly on the lower side of the lower cylindrical tube 52, miniaturizes the bubbles, and the diameter of the bubbles becomes minute.

Bubbles having a minute diameter lose buoyancy and are guided by the downward flow generated by the lower stirring blade 3 to move a long distance in the water tank, and as a result, stay for a long time.
In addition, since the upper water flow S2 in the upward flow circulates in the upper part of the water tank and acts like a lid, the bubbles that flow along with the downward flow stay in the center or bottom in the depth direction for a long time.
In addition, the bubbles released from the upper cylindrical pipe 51 are also refined by the upper water flow S2 as in the case of the lower cylindrical pipe 52, and this time, the upper water flow S2 and the vicinity of the upper part of the water tank stay for a long time.

Thus, the aeration stirrer of the first embodiment is provided with the upper stirring blade 2 that generates an upward flow at the upper portion of the rotating shaft 1 and the lower stirring blade 3 that generates a downward flow at the lower portion of the rotating shaft 1, A cylindrical body 4 that has a water intake 41 between the upper and lower stirring blades 2 and 3 and covers the periphery of the rotary shaft 1 is provided, and an air diffuser 5 that supplies bubbles to at least the lower side of the lower stirring blade 3 is provided. Therefore, the bubbles from the air diffuser 5 can be refined by the strong shearing action of the lower stirring blade 3, thereby increasing the diameter of the pores for supplying the bubbles and reducing the air outlet resistance. it can.
In addition, the refined bubbles stay in the lower part of the water tank for a long time along with the descending and rising water flow by the aeration stirrer, and the necessary oxygen dissolution rate can be obtained even if the amount of air supplied is small. And the power of the blower 53 of the diffuser 5 can be greatly reduced.
Further, the water flow of the lower agitating blade 3 can ensure a sufficient bottom portion flow rate and homogeneous agitation in the tank to prevent sludge accumulation.

  Then, the air diffuser 5 supplies air bubbles to the upper side of the upper stirring blade 2 so that the air bubbles from the air diffuser 5 are refined by the strong shearing action of the upper stirring blade 2, and the refined air bubbles are At the same time, it can stay in the upper part of the water tank for a long time.

  In addition, by providing pores for releasing air bubbles inside the upper and lower cylindrical tubes 51 and 52, the inner diameter of the upper and lower cylindrical tubes 51 and 52 is made substantially the same as the upper or lower opening of the cylindrical body 4. In addition, the bubbles can be made fine by the shear flow generated inside the upper and lower cylindrical tubes 51 and 52, and the water flow of the stirring blades 2 and 3 can be prevented from becoming an obstacle.

FIG. 2 shows a second embodiment of the aeration stirrer of the present invention.
The cylindrical tube 55 having a polygonal cross section is a diffuser tube in the case of increasing the amount of bubbles to be blown out, and more pores can be provided on the inner side than the lower tube 52 shown in FIG.
Depending on the amount of air, it is selected whether a plurality of lower cylindrical tubes 52 having a circular cross section are stacked or a cylindrical tube 55 having a polygonal cross section is provided.

In the aeration stirrer of the second embodiment, a cylindrical tube 55 having a polygonal cross section is disposed as the upper cylindrical tube 51.
In addition, since the other structure of the aeration stirrer of this 2nd Example is the same as that of 1st Example, the description is abbreviate | omitted.

  As described above, the aeration stirrer of the second embodiment is provided with pores inside the cylindrical tube 55 having a circular or polygonal cross section so that the pores are closely packed, and the negative pressure due to the water flow of the stirring blades 2 and 3 Can be used to reduce the power to blow air or supply bubbles at atmospheric pressure.

FIG. 3 shows a third embodiment of the aeration stirrer of the present invention.
In this aeration stirrer, the air diffuser 6 generates fine bubbles in the water and supplies oxygen-rich water containing the fine bubbles from the outside to generate fine bubbles in the water on the ground side. Yes.
In addition, the rotary shaft 1 is formed hollow, and the air diffuser 6 supplies oxygen-rich water containing fine bubbles into the rotary shaft 1, so that the fine bubbles are removed from the lower stirring blade 3 through the rotary shaft 1. Supply to the lower side.
In FIG. 3, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

Specifically, the upper cylindrical pipe 61 and the lower cylindrical pipe 62 are arranged at the same positions as the upper cylindrical pipe 51 and the lower cylindrical pipe 52 shown in FIG. Will release water containing bubbles.
The water is originally sewage in the water tank and is pumped up by the pump 66 and flows into the temporary storage tank 65.
Thereafter, water containing bubbles is generated by the microbubble generator, and is further discharged from the upper tube 61 and the lower tube 62 through the conduit 63.

  Further, the sewage flowing into the temporary storage tank 65 is piped so as to also flow through the conduit 64, flows inside the hollow rotary shaft 1 through the rotary joint 67, and is discharged from the lower opening of the rotary shaft 1. The

  Thus, in the aeration stirrer of the third embodiment, the air diffuser 6 generates fine bubbles in the water and supplies oxygen-rich water containing the fine bubbles from the outside. The water is generated on the side and the power of the blower of the air diffuser 6 is greatly reduced, and the micronized bubbles are kept in the water tank for a long time together with the water flow of the stirring blades 2 and 3, so that the necessary oxygen dissolution rate can be obtained even with a small amount of air. Can be obtained.

  In addition, the rotary shaft 1 is formed hollow, and the air diffuser 6 supplies oxygen-rich water containing fine bubbles into the rotary shaft 1, so that the fine bubbles are removed from the lower stirring blade 3 through the rotary shaft 1. Can be supplied to the lower side.

  As mentioned above, although the aeration stirrer of this invention was demonstrated based on the Example, this invention is not limited to the structure described in the said Example, The structure is changed suitably in the range which does not deviate from the meaning. be able to.

  Since the aeration stirrer of the present invention has a characteristic that it can efficiently aerate and stir with less power, it can be used widely and suitably as an aeration stirrer designed to save power. it can.

It is sectional drawing which shows 1st Example of the aeration stirrer of this invention. It is a fragmentary sectional view showing the 2nd example. It is sectional drawing which shows the 3rd Example.

DESCRIPTION OF SYMBOLS 1 Rotating shaft 11 Electric motor 2 Upper stirring blade 3 Lower stirring blade 4 Cylindrical body 41 Water intake 5 Air diffuser 51 Upper cylindrical tube 52 Lower cylindrical tube 53 Blower 54 Conduit 55 Cylindrical tube with a cross section 6 Air diffuser 61 Upper tube Pipe 62 Lower cylinder pipe 63 Conduit 64 Conduit 65 Temporary storage tank 66 Pump 67 Rotating joint

Claims (3)

An upper stirring blade for generating an upward flow is attached to the upper part of the rotating shaft, a lower stirring blade for generating a downward flow is attached to the lower part of the rotating shaft, and a water intake is provided between the upper and lower stirring blades. provided a tubular body covering the periphery in the vertical direction, it is provided immediately below the balloon portion of the downward flow of the lower cylindrical body of the lower part stirring blades, to substantially the same diameter and the lower opening of the cylindrical body the pores to release bubbles The pores for releasing bubbles, which are provided directly above the ring-shaped lower cylindrical tube provided on the inner peripheral side and the upward flow blowing portion on the upper side of the upper stirring blade, are substantially the same as the upper opening of the cylindrical body. An aeration stirrer provided with an air diffuser for supplying bubbles to a ring-shaped upper cylindrical tube provided on the inner peripheral side formed in a diameter . Air diffuser is provided with a microbubble generating apparatus, the aeration agitator according to claim 1, wherein the supplying water containing bubbles generated by the microbubble generating apparatus in the lower cylinder tube and the upper tube pipe. With the rotary shaft hollow to form, subjected feed water containing bubbles from an air diffuser inside the rotary shaft, to emit toward the balloon portion of the downward flow of the cylindrical body from the lower opening of the rotary shaft aeration agitator according to claim 2, characterized in that.

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