JP7426271B2 - impeller - Google Patents

Description

The present invention relates to an impeller for a vertical aeration agitation device for biological water treatment equipment.

2. Description of the Related Art As a biological treatment facility for biologically treating water to be treated such as sewage or sewage, a method using an oxidation ditch tank in which an endless circulation waterway is formed is known. Three types of aeration stirring devices for this oxidation ditch tank are known: a vertical shaft type, a horizontal shaft type, and an oblique shaft type.
Patent Document 1 discloses an impeller that is arranged in an oxidation ditch tank and rotates with its axis in a direction substantially perpendicular to the liquid level of the wastewater, that is, a direction that intersects with the liquid level, to aerate and agitate the wastewater. is listed.

JP2019-005728A

In order to aerate and stir the water to be treated in the oxidation ditch tank, it is necessary to keep the aeration and stirring device running for a long time. Therefore, it is desired that the impeller, which is in constant contact with the water to be treated, improves the efficiency of supplying oxygen to the water to be treated without increasing the power of the aeration stirring device.

Therefore, an object of the present invention is to provide an impeller that can reduce the power required for rotation by improving the efficiency of supplying oxygen to the water to be treated.

As a result of intensive studies on the above-mentioned problems, the inventors of the present invention have found that, in an impeller including a plurality of blades extending radially outward from the shaft and a connecting plate connecting the plurality of blades, the position of the radially outer end of the connecting plate is The present invention was completed based on the discovery that the efficiency of supplying oxygen to the water to be treated can be improved by installing the impeller on the outside in the radial direction of the impeller. That is, the present invention is the following impeller.

The impeller of the present invention for solving the above problems is an impeller that aerates and/or stirs water to be treated, and includes a shaft, a plurality of blades extending radially outward from the shaft, and a plurality of blades extending in the circumferential direction. a plurality of connecting plates arranged between two adjacent blade parts to connect the two blade parts, a gap is formed between the connecting plates and the shaft, and a gap is formed between the connecting plate and the shaft, The radially outer end of the connecting plate is radially outer than 90% of the length of the blade, which is the total length from the shaft to the radially outer end of the blade, when viewed from the axial direction. It is characterized by being installed in the position of

According to the impeller of the present invention, since the radially outer end of the connecting plate extends to the vicinity of the end of the blade, it is strong against the water to be treated that moves on the upper surface of the connecting plate due to the rotation of the impeller. A centrifugal force is applied. Therefore, the water to be treated is further accelerated on the upper surface of the connecting plate and can be scattered over a long distance. As a result, a large amount of oxygen is taken into the water to be treated, and oxygen can be efficiently supplied to the water to be treated.
In other words, when operating a vertical shaft type aeration agitator while keeping the oxygen supply constant, the impeller rotation speed can be suppressed, so the power supply required to rotate the impeller can be kept low. becomes possible.
Therefore, according to the impeller of the present invention, it is possible to effectively increase oxygen supply efficiency.

In the impeller of the present invention for solving the above problems, the length of the gap from the shaft to the connecting plate is 40 to 70% of the length from the shaft to the radially outer end of the connecting plate when viewed from the axial direction. %.
According to this feature, the size of the water passage hole formed by the gap from the shaft to the connecting plate is an appropriate size from the viewpoint of effectively increasing oxygen supply efficiency. In other words, by making sure that the length of the gap from the shaft to the connecting plate is at least 40% of the length from the shaft to the radially outer end of the connecting plate, a water passage hole that can secure a sufficient amount of water to be pumped can be created. can be formed. In addition, by ensuring that the length of the gap from the shaft to the connecting plate is at least 70% of the length from the shaft to the radially outer end of the connecting plate, the sufficient radial length of the connecting plate is ensured. Therefore, the water to be treated is accelerated on the upper surface of the connecting plate, and the droplets of the water to be treated can be scattered over a long distance.
Therefore, according to the impeller of the present invention, it is possible to effectively increase oxygen supply efficiency.

Further, an embodiment of the impeller of the present invention is characterized in that the blade portions are provided on both sides of the upper surface side and the lower surface side of the connecting plate.
According to this feature, the water to be treated that is pumped up from the water hole is scattered around the impeller by the blades provided on both sides of the upper and lower surfaces of the connecting plate, which improves oxygen supply efficiency. It becomes possible to increase the amount effectively.
In addition, since the water to be treated is stirred by the blades provided on the lower surface of the connecting plate, the water to be treated that has been supplied with a large amount of oxygen by scattering mixes with the water to be treated flowing in the flow path. I can do it. Thereby, oxygen can also be supplied toward the bottom of the flow path.

According to the present invention, it is possible to provide an impeller that can reduce the power required for rotation by improving the efficiency of supplying oxygen to the water to be treated.

FIG. 1 is a schematic explanatory diagram showing the configuration of the biological treatment facility of the present invention when an endless waterway is viewed from above. It is a schematic explanatory view showing the structure of the vertical axis type aeration stirring device of the present invention in a cross section of an endless waterway. FIG. 1 is a schematic perspective view showing an impeller in a first embodiment of the present invention. FIG. 1 is a schematic plan view showing an impeller in a first embodiment of the present invention. FIG. 3B is a schematic cross-sectional view along the VV direction of FIG. 3B showing the impeller in the first embodiment of the present invention. FIG. 3B is a schematic cross-sectional view along the VV direction of FIG. 3B showing the impeller in the first embodiment of the present invention, and is a schematic explanatory view for explaining the position of the end of the connecting plate. It is a schematic perspective view which shows the impeller in the second embodiment of this invention. FIG. 7 is a schematic plan view showing an impeller in a second embodiment of the present invention. FIG. 4B is a schematic cross-sectional view along the VV direction of FIG. 4B showing an impeller in a second embodiment of the present invention. FIG. 4B is a schematic cross-sectional view along the VV direction of FIG. 4B showing an impeller in a second embodiment of the present invention, and is a schematic explanatory view for explaining the size of the gap. It is a schematic perspective view which shows the impeller in the third embodiment of this invention. It is a schematic plan view which shows the impeller in the third embodiment of this invention. FIG. 4B is a schematic cross-sectional view along the VV direction of FIG. 4B showing an impeller in a third embodiment of the present invention. FIG. 4B is a schematic cross-sectional view along the VV direction of FIG. 4B showing an impeller in a third embodiment of the present invention, and is a schematic explanatory view for explaining the position of the end of the connecting plate and the size of the gap. FIG. 2 is a schematic perspective view showing an existing impeller. FIG. 2 is a schematic plan view showing an existing impeller. FIG. 6B is a schematic cross-sectional view along the VV direction of FIG. 6B showing an existing impeller. 3 is a graph showing simulation results of Example 1 of the present invention. It is a graph which shows the result of the simulation of Example 2 of this invention.

[First embodiment]
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic explanatory diagram showing the configuration of the biological treatment facility 1 when the endless waterway 2 in the first embodiment is viewed from above. Note that the arrows in the figure represent the circulation flow flowing through the endless waterway 2.

(Biological treatment equipment)
The biological treatment equipment 1 according to the present invention is used in an oxidation ditch method in which biological treatment is performed while circulating water to be treated in an endless waterway 2. The water to be treated is not particularly limited, and includes, for example, organic wastewater such as sewage, livestock wastewater, and factory wastewater.
As shown in FIG. 1, the biological treatment equipment 1 includes an endless waterway 2 formed by a surrounding wall 21 and a partition wall 22, a vertical shaft type aeration agitation device 3 installed in the endless waterway 2, and a guide plate 7. There is.

The endless water channel 2 consists of two straight water channels 2a extending in parallel, and a circulation channel 2b that connects the straight water channels 2a at both ends of the two straight water channels 2a to form a circulating flow to be treated.
In the biological treatment equipment 1 of the first embodiment, a vertical shaft type aeration stirring device 3 is installed near the partition wall 22 of the straight waterway 2a. Note that the vertical shaft type aeration stirring device 3 may be arranged in the circulation channel 2b.

The vertical shaft type aeration stirring device 3 performs surface aeration on the water to be treated in the flow path and supplies oxygen to the water to be treated. Further, the vertical shaft type aeration stirring device 3 forms a circulating flow in the endless waterway 2 together with the guide plate 7 arranged nearby. Specifically, the vertical shaft type aeration stirring device 3 generates an agitation flow in the water to be treated, and the flow of this agitation flow is guided by a guide plate 7 placed nearby to circulate through the endless waterway 2. form a flow.

(Vertical shaft type aeration stirring device)
FIG. 2 is a schematic explanatory diagram showing the structure of the vertical shaft type aeration stirring device 3 in this embodiment. As shown in FIG. 2, the vertical shaft type aeration and stirring device 3 includes an impeller 31 for aerating and stirring the water to be treated, and a drive unit 33 that supplies power for rotating the impeller 31.
Further, the impeller 31 in this embodiment includes a shaft 31C connected to the drive portion 33, a plurality of blade portions 31A radially attached to the shaft 31C, and a connecting plate 31B connecting the plurality of blade portions 31A.

Further, FIG. 3A shows a perspective view of the impeller 31 according to the first embodiment of the present invention, and FIG. 3B shows a plan view of the impeller 31 according to the first embodiment of the present invention viewed from the axial direction. . As shown in FIGS. 3A and 3B, the connecting plate 31B is installed with a gap between it and the shaft 31C, and this gap forms a water passage hole 31D for pumping the water to be treated. .

Next, the operation of the vertical shaft type aeration stirring device 3 will be explained.
As shown in FIG. 2, the vertical shaft type aeration stirring device 3 is installed such that the water passage hole 31D is placed in the water to be treated, and the tip of the blade portion 31A is exposed above the water surface. When the impeller 31 is rotated in this position, the water to be treated that has been scraped up by the blade portion 31A is scattered around as droplets from the tip of the blade portion 31A due to centrifugal force. The guide plate 7 placed near the vertical shaft type aeration stirring device 3 is installed so that the upper end is located near the water surface, and the droplets of the water to be treated can be scattered far beyond the guide plate 7. I can do it. Splashes of water to be treated take in air while flying through the atmosphere, and land on the water to be treated in a state containing air. Thereby, oxygen can be supplied to the water to be treated.

When the water to be treated is scattered from the blade portion 31A, the water to be treated flows into the water passage hole 31D formed between the connecting plate 31B and the shaft 31C, so that the water to be treated is continuously scattered around the impeller 31. I can do it.

Further, the blade portion 31A located in the water to be treated forms a stirring flow in the water to be treated. The stirring flow is guided downstream by the guide plate 7 to form a circulating flow in the endless water channel 2.

Next, each part of the impeller 31 will be explained in detail.
<Axis>
As shown in FIG. 2, the shaft 31C is connected to the drive section 33, and its purpose is to rotationally drive the impeller 31 using the power from the drive section 33.
The shape of the shaft 31C is not particularly limited as long as the impeller 31 can be rotationally driven by the power from the drive unit 33. For example, it may have a cylindrical shape, a polygonal column shape, or the like. Further, the shaft 31C may have a hollow structure in which the inside is hollow. In this case, since the weight of the entire impeller 31 can be reduced while maintaining the strength of the shaft 31C, the water to be treated can be aerated and stirred with low power.

The material of the shaft is not particularly limited, and examples thereof include metals such as iron and stainless steel, resins such as hard plastics, and the like. From the viewpoint of strength and corrosion resistance, a corrosion-resistant metal such as stainless steel is preferable.

As shown in FIG. 2, the shaft 31C is composed of a plurality of shafts and includes a connecting portion 31E that connects the plurality of shafts. By making the shaft 31C divisible into a plurality of shafts, the position of the impeller 31 relative to the depth of the water to be treated can be adjusted. For example, when installing the impeller 31 near the bottom of the water to be treated, the length of the shaft 31C may be extended by dividing the connecting portion 31E and adding a shaft (not shown) for stretching. can.

Moreover, as shown in FIG. 2, a lifting device 31F may be provided. The lifting device 31F is a device for raising and lowering the impeller 31, and by providing the lifting device 31F, the height position of the impeller 31 can be finely adjusted. By finely adjusting the height of the impeller 31, the amount of droplets formed by the impeller 31 and the scattering distance can be adjusted, which improves the efficiency of supplying oxygen to the water to be treated, thereby reducing the power required for rotation. The effect of the present invention of lowering can be further exhibited.

<Blade part>
As shown in FIG. 3A, the blade portion 31A is formed to extend radially outward from the shaft 31C, and a plurality of blade portions 31A are attached to the shaft 31C. In the impeller 31 of the first embodiment, the blade portion 31A is composed of two plate members, a blade plate 310A and a blade plate 310B, and the blade plate 310A has a plate surface substantially parallel to the axial direction (substantially vertical direction). will be installed. The vane plate 310B is formed continuously with the upper end of the vane plate 310A, and is installed so as to be inclined from the vane plate 310A toward the front in the rotational direction of the impeller 31. Moreover, as shown in FIG. 3B, the vane plate 310A (up to the broken line) is fixed radially from the axis of the shaft 31C. By fixing the blade plates 310A radially from the axis, it is easy to balance the rotation of the impeller 31.

The vane plate 310A and the vane plate 310B may be formed by bending a single plate member, or may be formed by combining separate plate members. When formed by bending a single plate member, the strength of the entire blade portion 31A can be maintained high. Further, when forming the blade by combining separate plate members, it is possible to change the shape to various shapes by replacing each vane.

Further, as shown in FIG. 3C, the blade portion 31A is inclined upward from the shaft 31C toward the outer side in the impeller radial direction. Thereby, the water to be treated can be scattered over a long distance, so that the efficiency of the oxygen supply rate can be increased. The angle between the blade portion 31A and the water surface of the water to be treated is, for example, 10 to 80°, preferably 20 to 60°.

Further, the shape of the lower end of the blade plate 310A is such that the width of the blade plate 310A increases from the radially outer tip toward the shaft 31C. As a result, the blade plate 310A becomes larger near the shaft 31C disposed inside the water to be treated, so that a strong stirring flow can be formed.

The number of blade portions 31A installed is not particularly limited. The number of blades 31A to be installed is preferably about 2 to 12 equally spaced when the impeller 31 is viewed from above. In this case, the water to be treated can be effectively stirred and dispersed into the atmosphere. More preferably, the number of impellers 31 installed is 6 to 8 equally spaced when the impeller 31 is viewed from above. In this case, the strength of the generated agitation flow and the amount of water to be treated that are scattered into the atmosphere are optimized, so that the water to be treated can be efficiently aerated and stirred.

Further, as shown in FIG. 3A, a connecting plate 31B is connected between the circumferentially adjacent blade plates 310A. The connecting plate 31B is fixed to the middle of the blade plate 310A, and the blade plate 310A has an upper blade plate 311 located on the upper surface side of the connecting plate 31B and a lower blade plate located on the lower surface side of the connecting plate 31B. It is divided into 312 parts. The blade upper part 311 has a function of scattering the water to be treated, which is pumped up from the water passage hole 31D by the rotation of the impeller 31, around the impeller 31. The lower blade plate 312 is disposed in water and mainly forms a stirring flow in the water to be treated. Further, by arranging the tip of the lower blade plate 312 above the surface of the water to be treated, the water to be treated can be scattered around the impeller.

As shown in FIG. 3A, the blade plate 310B is inclined toward the front in the rotational direction, and guides the water to be treated that has been scraped up by the blade plate 310A to the outside in the radial direction along the blade plate 310A. By providing the vane plate 310B, the amount of scattered water to be treated is increased, and the oxygen supply efficiency can be further improved. Note that the angle formed by the blade plate 310B and the blade plate 310A is, for example, preferably 100 to 170°, more preferably 110 to 160°.

The material of the vane plate 310A and the vane plate 310B is not particularly limited, and examples thereof include metals such as iron and stainless steel, resins such as hard plastics, and the like. From the viewpoint of strength and corrosion resistance, a corrosion-resistant metal such as stainless steel is preferable.

Note that the shape of the blade portion 31A is not particularly limited; for example, in the first embodiment, the plate surface of the blade plate 310A is installed approximately parallel to the axial direction (substantially vertical direction); The plate surface may be fixed at an angle to the water surface. Alternatively, the blade portion 31A may be formed only with the blade plate 310A without providing the blade plate 310B.

<Connecting board>
As shown in FIGS. 3A to 3C, the connecting plate 31B is fixed to the blade plate 310A with a gap between it and the shaft 31C, and the gap forms a water passage hole 31D through which the water to be treated passes. do.

The connecting plate 31B is formed of a plate member, and its material is not particularly limited, and examples thereof include metals such as iron and stainless steel, resins such as hard plastics, and the like. From the viewpoint of strength and corrosion resistance, a corrosion-resistant metal such as stainless steel is preferable.

Note that the shaft 31C, the blade portion 31A, and the connecting plate 31B may be connected as separate bodies, or may be formed integrally.

In the impeller 31 of the first embodiment, as shown in FIG. 3D, the radially outer end 313 of the connecting plate 31B extends from the shaft 31C to the radially outer end of the blade portion 31A when viewed from the direction of the shaft 31C. It is arranged at a position (shaded area) radially outward from 90% of the length (X) of the blade part 31A, which has a total length up to the part.
Note that the end portion 313 of the connecting plate 31B may exceed 100% of the length (X) of the blade portion 31A (the end portion of the connecting plate is located outside the end portion of the blade portion 31A). , preferably 100% or less.

The water to be treated flowing from the water passage hole 31D is accelerated by centrifugal force as it flows on the upper surface of the connecting plate 31B. The flow of water to be treated accelerated on the upper surface of the connecting plate 31B is vigorously scattered from the blade portion 31A. When the end portion 313 of the connecting plate 31B is placed outside 90% of the length (X) of the blade portion 31A, a strong centrifugal force is applied, so that the flying distance of the droplets increases. Therefore, the amount of oxygen taken into the droplets increases, resulting in the effect of improving oxygen supply efficiency.
By optimizing the position of the end 313 of the connecting plate 31B, it is possible to scatter the water to be treated farther than with a conventional impeller, so it is possible to effectively aerate the water to be treated. becomes.

(Guide plate)
The purpose of the guide plate 7 is to stir and circulate the water to be treated in the endless waterway 2 by rectifying the stirring flow generated by the impeller 31 of the vertical shaft type aeration stirring device 3.
As shown in FIG. 1, the guide plate 7 is fixed to the partition wall 22 so as to cover the upstream side of the vertical shaft type aeration stirring device 3.
As shown in FIG. 2, the installation height of the guide plate is such that the upper end is located approximately at the water surface of the water to be treated, and the lower end is located at the same level as or slightly higher than the lower end of the vertical shaft type aeration stirring device. By locating the upper end of the guide plate substantially on the water surface, droplets scattered by the rotation of the impeller 32 land on the surrounding water, thereby increasing oxygen supply efficiency. It also has an excellent effect of eliminating floating scum.
Further, by installing the lower end of the guide plate at the same level as the lower end of the vertical shaft type aeration stirring device, the stirring flow generated by the rotation of the impeller 32 can be guided to a predetermined position.

[Second embodiment]
4A to 4C are a perspective view, a plan view, and a sectional view, respectively, showing the structure of the impeller 41 in the second embodiment.
This will be explained in detail below using drawings. Note that the blade portion 41A and the shaft 41C are the same as the blade portion 31A and the shaft 31C in the first embodiment, so a description thereof will be omitted.

<Connecting board>
In the impeller 41 of the second embodiment, as shown in FIG. 4D, when viewed from the direction of the shaft 41C, the length (Y1) of the gap from the shaft 41C to the connecting plate 41B is the diameter of the connecting plate 41B from the shaft 41C. It is 40 to 70% of the length (Y2) to the outer end 413 in the direction.

If the length (Y1) of the gap from the shaft 41C to the connecting plate 41B is 40 to 70% of the length (Y2) from the shaft 41C to the radially outer end 413 of the connecting plate 41B, the water passage hole 41D A sufficient amount of water to be treated can be secured. Therefore, the amount of scattered water to be treated is increased, and the oxygen supply efficiency is improved.
By optimizing the gap between the connecting plate 41B and the shaft 41C, more water to be treated can be scattered compared to conventional impellers, making it possible to effectively aerate the water to be treated. becomes.

[Third embodiment]
5A to 5C are a perspective view, a plan view, and a sectional view, respectively, showing the structure of the impeller 51 in the third embodiment.
This will be explained in detail below using drawings. Note that the blade portion 51A and shaft 51C are the same as the blade portion 31A and shaft 31C in the first embodiment, and the blade portion 41A and shaft 41C in the second embodiment, so a description thereof will be omitted.

<Connecting board>
In the impeller 51 in this embodiment, as shown in FIG. 5D, the end portion 513 of the connecting plate 51B is arranged at a position (shaded area) radially outward from 90% of the length (X) of the blade portion 51A. . Further, the length (Y1) of the gap from the shaft 51C to the connecting plate 51B is 40 to 70% of the length (Y2) from the shaft 51C to the radially outer end 513 of the connecting plate 51B. According to these features, while ensuring a sufficient amount of water to be treated pumped by the rotation of the impeller 51, when the water to be treated flows on the upper surface of the connecting plate 51B, centrifugal force is applied to accelerate the water, It has the effect of increasing the flight distance of droplets.
By optimizing the gap between the connecting plate 51B and the shaft 51C and the position of the end portion 513 of the connecting plate 51B, the conventional impeller, the impeller 31 of the first embodiment, and the impeller 41 of the second embodiment can be In comparison, it becomes possible to effectively aerate the water to be treated.
Moreover, according to these features, it becomes possible to effectively increase oxygen supply efficiency with even less power.

[Example 1]
The relationship between power and aeration amount of the impeller 31 of the first embodiment, the impeller 51 of the third embodiment, and the existing impeller 61 (FIGS. 6A to 6B) was compared by simulation.
In the simulation, the outer diameters of the impeller 31 of the first embodiment, the impeller 51 of the third embodiment, and the existing impeller 61 were made the same.
In the existing impeller 61, the position of the end of the connecting plate 61B is 85% of the length (X) of the blade part 61A, and the length (Y1) of the gap from the shaft 61C to the connecting plate 61B is set to 85% of the length (X) of the blade part 61A. It was set to 35% of the length (Y2) to the radially outer end of 61B.
In the impeller 31 of the first embodiment, the position of the end of the connecting plate 31B is 100% of the length (X) of the blade part 31A, and the length (Y1) of the gap from the shaft 31C to the connecting plate 31B is the axis. The length was set to 35% of the length (Y2) from 31C to the radially outer end of the connecting plate 31B.
In the impeller 51 of the third embodiment, the position of the end of the connecting plate 51B is 100% of the length (X) of the blade portion 51A, and the length (Y1) of the gap from the shaft 51C to the connecting plate 51B is the axis. It was set to 55% of the length (Y2) from 51C to the radially outer end of the connecting plate 51B.

The results of the simulation are shown in the graph of FIG. The horizontal axis of the graph is the power, and the vertical axis is the aeration amount. Note that the amount of aeration was defined as the amount of droplets of water to be treated passing through a predetermined area.

As shown in FIG. 7, when the power used to rotate each impeller was the same, the impeller 51 of the third embodiment had the highest aeration amount substitute index, followed by the impeller 31 of the first embodiment. The result was that the existing impeller 61 was the lowest.
Furthermore, when looking at the same amount of aeration, the impeller 51 of the third embodiment has the highest energy efficiency, followed by the impeller 31 of the first embodiment, and the existing impeller 61 has the lowest energy efficiency. Ta.

[Example 2]
Example 2 compared the relationship between impeller rotation speed and oxygen supply efficiency between the impeller 51 of the third embodiment and the existing impeller 61 by simulation. Other conditions were the same as in Example 1.

The results of the simulation are shown in the graph of FIG. The horizontal axis of the graph is the rotation speed of the impeller, and the vertical axis is the oxygen supply efficiency. The oxygen supply efficiency is the amount of oxygen supplied to the water to be treated divided by the amount of power per unit time, and the higher the efficiency, the more efficiently oxygen can be supplied with less power.

As shown in FIG. 8, when the rotational speed of each impeller was the same, the impeller 51 of the third embodiment had a higher oxygen supply efficiency than the existing impeller 61.

In addition, the embodiment mentioned above shows an example of the impeller of an aeration stirring device. The impeller according to the present invention is not limited to the embodiments described above, and the impeller according to the embodiments described above may be modified without changing the gist of the present invention.

For example, two blades and two connecting plates may be installed coaxially and vertically.
This allows the impeller placed on the lower side to be completely submerged in the water to be treated, stirring the water to be treated, and the impeller placed on the upper side to disperse the water to be treated into the atmosphere, resulting in aeration. Stirring power can be improved while maintaining efficiency.

Further, the structure may be such that the angle of the blade plate with respect to the axis and the angle of the blade plate or connecting plate with respect to the axis can be easily changed after installation of the impeller. In this case, the shape of the impeller can be easily changed on-site to provide optimum aeration and agitation performance depending on the viscosity of the water to be treated.

The impeller of the present invention can be suitably used in a vertical shaft type aeration stirring device for biological water treatment equipment.

1 Biological treatment equipment, 2 Endless waterway, 2a Straight waterway, 2b Circulation waterway, 21 Surrounding wall, 22 Compartment wall, 3 Vertical shaft type aeration agitation device, 31, 41, 51, 61 Impeller, 31A, 41A, 51A, 61A Vane section, 31B, 41B, 51B, 61B Connecting plate, 31C, 41C, 51C, 61C Shaft, 31D, 41D, 51D, 61D Water hole, 310A, 310B Vane plate, 311 Vane plate upper part, 312 Vane plate lower part, 313 , 413, 513 End of connecting plate, 31E Connecting part, 31F Lifting device, 33 Drive unit, 7 Guide plate, X Length of blade, Y1 Length of gap, Y2 Length to end of connecting plate

Claims (3)

An impeller that aerates and/or stirs water to be treated,
axis and
a plurality of vanes extending radially outward from the shaft;
A plurality of connecting plates arranged between two adjacent blade parts in the circumferential direction and connecting the two blade parts,
A gap is formed between the connecting plate and the shaft,
The radially outer end of the connecting plate is radially longer than 90% of the length of the blade, which is the total length from the axis to the radially outer end of the blade, when viewed from the axial direction. installed in an outside position,
When viewed from the axial direction, the length of the gap from the shaft to the connecting plate is 40 to 70% of the length from the shaft to the radially outer end of the connecting plate. , impeller. The impeller according to claim 1, wherein a position of the connecting plate radially outward from the axis coincides with a position of the blade portion radially outward from the axis. The impeller according to claim 1 or 2, wherein the blade portions are provided on both sides of the upper surface and the lower surface of the connecting plate.