JP2009247927A - Aeration agitator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aeration agitator capable of effectively aerating and agitating with a small power consumption. <P>SOLUTION: The aeration agitator which aerates from the air into the water through a rotating hollow shaft 2 includes: an aerating body 3 composed of two disks 8, 9 parting each other in the axial direction and having a plurality of openings 31 on their periphery, which is arranged coaxially at the chip of the hollow shaft 2; an agitating shaft 4 communicating the inner part of the aerating body 3 with the hollow shaft 2 and having an under part impeller 5 generating a vertical downward flow at the chip, which is coaxially arranged at the under part of the aerating body 3; and a draft tube 6 arranged around the aerating body 3 and the agitating shaft 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

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 it in the 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 an aeration stirrer that is configured to aerate from the air into the water through a rotating hollow shaft, and is composed of two discs separated in the axial direction, A diffused gas having a plurality of openings on the outer periphery is arranged coaxially at the tip of the hollow shaft, and the inside of the diffused gas communicates with the hollow shaft to generate a downward flow at the tip of the diffused gas. A stirring shaft provided with a lower impeller is disposed coaxially, and a draft tube is disposed around the stirring shaft and the diffused gas.

  In this case, a current plate having the same diameter as that of the draft tube can be provided above the draft tube.

  Also, an upper impeller that generates an upward flow is disposed on the hollow shaft above the diffused gas, and a draft tube is extended to the periphery of the upper impeller, and an opening is provided around the diffused gas of the draft tube. Can do.

  Further, the draft tube can be provided with a diameter smaller than that of the diffused gas above and below the diffused gas, and can be provided with a diameter larger than that of the diffused gas in the vicinity of the diffused gas.

  In addition, the diffused gas can be graded up and down so that the outer peripheral sides of the disks are close to each other.

According to the aeration stirrer of the present invention, the aeration stirrer is configured to aerate from the air to the water through a rotating hollow shaft, and is composed of two discs spaced apart in the axial direction. A diffused gas having an opening is arranged coaxially at the tip of the hollow shaft, and the lower impeller that communicates the inside of the diffused gas with the hollow shaft and generates a downward flow at the tip of the diffused gas is provided. Since the stirring shaft is arranged coaxially and a draft tube is arranged around the stirring shaft and the diffused gas, it is compressed from the opening at the outer peripheral portion by rotating the diffused gas communicating with the hollow shaft. Air can be discharged in a substantially horizontal direction, so that air can be introduced into the water by using an electric motor instead of a blower that requires a large amount of power, and aeration can be achieved by power saving. Can be stirred That.
Further, since the compressed air introduced into the water is sheared by the lower impeller, the bubble diameter is reduced, and the surface area of the entire bubble is increased, so that the efficiency of dissolving oxygen in water can be increased.
Furthermore, due to the action of the lower impeller and the draft tube, the air introduced into the water once reaches the bottom of the aquarium, so the residence time of the air in the water is longer than when it is simply introduced, Increases oxygen dissolution efficiency.

  In this case, a rectifying plate having the same diameter as that of the draft tube is provided above the draft tube, so that a part of the compressed air to be moved to the water surface is suppressed by the rectifying plate, and the water flow generated by the lower impeller and the draft tube is reduced. Therefore, it can introduce | transduce downward, Thereby, the residence time in the water of the compressed air introduced in water can be lengthened, and the ratio in which the oxygen in air melt | dissolves in water can be increased.

  Also, an upper impeller that generates an upward flow is disposed on the hollow shaft above the diffused gas, and a draft tube is extended to the periphery of the upper impeller, and an opening is provided around the diffused gas of the draft tube. Thus, water can be sucked from the opening of the draft tube with the upper and lower impellers, mixed with the compressed air from the diffused gas, and discharged from the upper and lower parts of the draft tube.

  In addition, by providing a draft tube with a diameter smaller than that of the diffused gas above and below the diffused gas and larger than the diffused gas in the vicinity of the diffused gas, the upper and lower impellers can be sucked and discharged, and mixed with compressed air. The action can be strengthened.

  In addition, the flow of water flowing in from the opening of the draft tube by suction of the upper and lower impellers can be adjusted by providing a gradient to the diffused gas so that the outer peripheral sides of the disks are close to each other.

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

FIG. 1 shows a first embodiment of the aeration stirrer of the present invention.
This aeration stirrer is for aeration from the air into the water through a rotating hollow shaft 2 and is composed of two discs 8 and 9 spaced apart in the axial direction, and has a plurality of openings 31 on the outer periphery. The diffused gas 3 is coaxially disposed at the tip of the hollow shaft 2, and the interior of the diffused gas 3 and the hollow shaft 2 are communicated with each other.
A stirring shaft 4 having a lower impeller 5 that generates a vertical downward flow at the tip is coaxially disposed at the lower portion of the diffused gas 3, and a draft tube 6 is disposed around the stirred shaft 4 and the diffused gas 3. Has been established.

The hollow shaft 2 is installed in the vertical direction, and is disposed in the water of the water tank 12 from the air so as to be rotated by the electric motor 1.
A diffused gas 3 is provided at the tip of the hollow shaft 2, and a stirring shaft 4 having a lower impeller 5 is provided below the diffused gas 3 so as to rotate integrally.

As shown in FIG. 4, the diffused gas 3 is provided with a plurality of fine openings 31 by radially attaching a plurality of blades 10 between the upper and lower disks 8, 9 on the outer periphery thereof.
Note that the installation interval of the blades is several millimeters to several tens of millimeters, thereby forming the openings 31 as pores.
Further, instead of attaching the blade, it is also possible to attach a large-diameter short cylinder provided with openings such as slits, lattice holes or round holes so as to be sandwiched between the upper and lower disks 8 and 9.

When the electric motor 1 rotates, the external air A is sucked from the upper part of the hollow shaft 2 and is discharged in the horizontal direction as compressed air B from the opening 31 of the diffused gas 3.
In the draft tube 6 provided below the surface of the water, a vertical downward flow is generated by the lower impeller 5, whereby a part of the compressed air B is brought vertically downward. The compressed air B is further sheared by the lower impeller 5, and the bubble diameter is further reduced.

  The draft tube 6 may be installed on the electric motor 1 side, or may be installed on the water tank side. However, the diffused gas 3 and the lower impeller 5 need to be disposed in the draft tube 6. There is.

FIG. 2 shows a second embodiment of the aeration stirrer of the present invention.
This aeration stirrer is provided with a circular rectifying plate 7 having substantially the same diameter as the draft tube 6 above the draft tube 6 in addition to the same configuration as in the first embodiment.
Note that the same members as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

A part of the compressed air B is vertically upward due to buoyancy, that is, tries to move to the water surface, but is blocked by the rectifying plate 7 provided on the upper part of the diffused gas 3 and is introduced vertically downward according to the water flow generated by the lower impeller 5. Is done.
Thereby, the residence time in the water of the compressed air B introduced into the water increases, and thus the rate at which oxygen in the air dissolves in the water increases.

FIG. 3 shows a third embodiment of the aeration stirrer of the present invention.
In this aeration stirrer, in addition to the same configuration as in the first embodiment, an upper impeller that generates an upward flow is disposed on the hollow shaft 2 above the diffused gas 3, and the draft tube 6 extends to the periphery of the upper impeller. And an opening 61 is provided around the diffused gas 3 in the draft tube 6.
The draft tube 6 is provided with a diameter smaller than that of the diffused gas 3 above and below the diffused gas 3 and larger than that of the diffused gas 3 near the diffused gas.
Note that the same members as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.

The upper impeller 11 is different from the lower impeller 5 in the direction of water flow generation, and can generate a water flow vertically upward.
The flow rate of the vertical water flow can be changed by changing the sizes of the upper impeller 11 and the lower impeller 5, but the lower impeller 5 is introduced into the water by making it larger than the upper impeller 11. It is desirable to feed a large amount of the compressed air B that is vertically downward.

In addition, the diffused gas 3 is inclined up and down so that the outer peripheral sides of the discs 8 and 9 are close to each other, but this causes pressure when the air sucked through the hollow shaft 2 is discharged in the radially outward direction. The compressed air is more easily released.
Further, since the diffused gas 3 has a vertical gradient in the vertical direction, the flow of water flowing from the opening 61 of the draft tube 6 by suction of the upper and lower impellers can be adjusted.

FIG. 5 shows the operation of the aeration stirrer of the third embodiment.
The water flow generated by the upper impeller 11 and the lower impeller 5 generates a circulating flow in the upper and lower parts in the water tank 12, respectively.
At the same time, the compressed air B released from the diffused gas 3 is entrained, and an upper jet flow C and a lower jet flow D containing bubbles are generated.

Part of the oxygen contained in the upper jet stream C dissolves in water, but its dissolution efficiency is low because it reaches the water surface quickly.
On the other hand, the lower jet flow D reaches the bottom of the water tank, moves in the horizontal direction of the water tank, then flows vertically upward on the wall surface of the water tank, and a part is sucked into the aeration stirrer again and circulates in the water tank 12. To do.
Part of the air contained in the lower jet stream D moves to the surface of the water by its buoyancy and is released into the atmosphere, but in particular, the bubbles sheared to a fine size by the lower impeller 5 have a small buoyancy. Therefore, it is possible to stay in the water tank 12 for a long time according to the water flow, so that the transfer efficiency of oxygen into the water is increased.

  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 sectional drawing which shows the 2nd Example. It is sectional drawing which shows the 3rd Example. It is a perspective view which shows an example of a diffused gas. It is sectional drawing which shows the effect | action of the aeration stirrer of 3rd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric motor 2 Hollow shaft 3 Air diffuser 31 Opening part 4 Stirring shaft 5 Lower impeller 6 Draft tube 61 Opening part 7 Current plate 8 Upper disk 9 Lower disk 10 Blade 11 Upper impeller 12 Water tank A External air B Compressed air C Upper jet flow D Lower jet flow

Claims (5)

  An aeration stirrer configured to aerate from the air into the water through a rotating hollow shaft, which comprises two discs spaced apart in the axial direction, and a diffused gas having a plurality of openings on the outer peripheral portion. A stirring shaft having a lower impeller for generating a downward flow at the tip is coaxially disposed at the lower end of the diffused gas. An aeration stirrer characterized in that a draft tube is disposed around the stirring shaft and the diffused gas.   2. The aeration stirrer according to claim 1, wherein a rectifying plate having substantially the same diameter as the draft tube is provided above the draft tube.   An upper impeller that generates an upward flow is disposed on the hollow shaft above the diffused gas, and a draft tube is extended to the periphery of the upper impeller, and an opening is provided around the diffused gas of the draft tube. The aeration stirrer according to claim 1 or 2, characterized by the above.   The aeration stirrer according to claim 3, wherein the draft tube is provided with a diameter smaller than that of the diffused gas above and below the diffused gas, and larger than that of the diffused gas in the vicinity of the diffused gas.   The aeration stirrer according to claim 1, 2, 3 or 4, wherein the diffused gas is provided with a gradient in the vertical direction so that the outer peripheral sides of the disks are close to each other.

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