JP2005296850A - Low speed stirrer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve the conservation of energy by reducing the required power of a low speed stirrer and to dispense with a long rotary shaft even in a deep reaction tank to prevent an increase in weight and cost. <P>SOLUTION: A draft tube 7 is provided to the center part of a reaction tank 1 of an activated sludge method so that the lower end is positioned in the vicinity of the base 14 of the reaction tank 1 and a rotary shaft 4 rotated at a low speed is suspended into the draft tube 7 from a drive part 2 installed on the top panel 8 of the reaction tank 1. Lower blades 6 for vertically imparting a flow to the liquid in the draft tube 7 and upper blades 5 for imparting the flow to the liquid in the vicinity of a liquid surface 13 in a centrifugal direction are provided to the rotary shaft 4. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a low-speed stirrer used for stirring a liquid in a reaction tank to give a low-speed flow.

A stirrer is provided in the reaction tank in order to give a flow to the liquid in the reaction tank to prevent sludge precipitation and to perform the treatment efficiently.
As a low-speed stirrer used in the reaction tank, a rotating shaft is suspended from the drive unit installed on the top plate of the reaction tank into the reaction tank, and the outer diameter of the rotation is located near the bottom of the reaction tank. The lower blades have a large diameter close to the inner diameter, and the upper blades have a rotational outer diameter smaller than the lower blades at positions near the liquid level (see Patent Document 1).

However, this low speed stirrer requires a large amount of power because the diameter of the lower blade is large. In addition, there is no problem if the reaction tank has a depth of about 3 to 5 m. However, in a deep reaction tank having a depth of 10 m, it is necessary to provide a long rotating shaft corresponding to the depth. Since the diameter of the shaft, the bearing, the output of the drive unit, etc. must be increased, the weight of the apparatus increases and the cost increases.
JP 2000-237780 A

  The present invention solves the above-mentioned problem about the low-speed stirrer used in the reaction tank, can reduce the required power and save energy, and it is not necessary to provide a long rotating shaft even in the deep reaction tank, An object of the present invention is to provide a low-speed stirrer that does not cause an increase in weight and cost.

  The low-speed stirrer of the present invention is provided with a draft tube whose lower end is located near the bottom surface in the center of the reaction tank, and a rotating shaft that rotates at a low speed from the drive unit installed on the top plate of the reaction tank into the draft tube. The above problem is solved by providing the rotating blade with a lower blade that gives a flow in the vertical direction to the liquid in the draft tube and an upper blade that gives a flow in the centrifugal direction to the liquid near the liquid surface.

In this low-speed stirrer, when the rotating shaft is driven to rotate the upper blade and the lower blade at a low speed, the lower blade gives a flow in the vertical direction to the liquid in the draft tube, and the liquid outside the draft tube This creates a flow in the opposite direction. Since a flow is given to the liquid to the bottom of the reaction tank, sedimentation of sludge is prevented.
Note that the liquid near the liquid level becomes stagnant with only the lower blade and the draft tube, but the upper blade gives a flow in the centrifugal direction to the liquid near the liquid surface. As a result, a liquid flow state near the liquid surface is improved.
Therefore, the stirring effect is high. Moreover, when it uses for activated sludge process, a favorable result is obtained.
In addition, this low-speed stirrer does not require the lower blades to have a large diameter close to the inner diameter of the reaction tank, and lower blades having a diameter smaller than the inner diameter of the draft tube are used, so that the required power is reduced to save energy. Can do.

When used in a reaction tank of the carrier-added activated sludge method, the lower blade and the upper blade rotating at low speed generate a low-speed flow in the liquid and float the carrier added in the liquid. It is also possible to prevent the bacteria from being killed by causing the carrier to which the bacteria are attached to settle without being damaged and becoming compacted.
Even when the reaction vessel is a deep reaction vessel, it is not necessary to provide a long rotating shaft corresponding to the depth of the reaction vessel, and this can be dealt with by simply extending the length of the draft tube. Therefore, it is not necessary to increase the diameter of the rotating shaft, the bearing, the motor output, and the like.

  The low speed stirrer of the present invention can reduce the required power and save energy by making the lower blade smaller in diameter. Further, it is not necessary to provide a long rotating shaft corresponding to the depth of the reaction tank, and an increase in weight and cost can be prevented.

FIG. 1 is a configuration diagram of a reaction tank of a support-added activated sludge process equipped with a low-speed stirrer according to an embodiment of the present invention.
In FIG. 1, a draft tube 7 is provided vertically at the center of the reaction vessel 1. This draft tube 7 is cylindrical and has a height that is about 2/3 of the depth of the liquid in the reaction tank 1, and the lower end is located at a position that maintains an appropriate gap through which the liquid can flow with the bottom surface 14. It is installed, and an appropriate distance is easily maintained between the upper end and the liquid level 13 so that the liquid can be sucked.

A driving unit 2 is installed at the center of the top plate 8 of the reaction tank 1, and a rotating shaft 4 connected to the driving unit 2 via a coupling 3 is suspended in a draft tube 7. . The rotating shaft 4 is provided with a lower blade 6 that gives a flow in the vertical direction to the liquid in the draft tube 7 and an upper blade 5 that gives a flow in the centrifugal direction to the liquid near the liquid surface 13.
When the sewage sludge is treated in the reaction tank 1, the carrier 10 on which bacteria are attached and regenerated is added to the sewage sludge in the reaction tank 1, and the rotary shaft 4 is driven by the drive unit 2 to Low speed rotation of 3 to 30 min ⁻¹ (preferably 6 to 15 min ⁻¹ ) is given to the lower blade 6.

  When the rotating shaft 4 is rotated forward, the lower blade 6 rotates counterclockwise as viewed from above, and a downward flow 11 in the vertical direction is given to the liquid in the draft tube 7, and the liquid is discharged from the lower end of the draft tube 7. As it flows out, an upward flow 16 is generated in the liquid outside the draft tube 7. The raised liquid is sucked toward the center by the lower blade 6 and flows into the draft tube 7 from the upper end of the draft tube 7.

Since the upper blade 5 gives the horizontal flow 12 in the centrifugal direction to the liquid near the liquid surface 13, the liquid strikes the side wall 9 of the reaction tank 1 and moves downward, and is sucked toward the center by the lower blade 6.
At this time, a mixed flow 17 due to the upward flow 16 and the horizontal flow 12 is also generated, the state of the liquid flow near the liquid surface is improved, and the lower layer sewage sludge and the upper layer sewage sludge are also mixed.
In this way, since the flow is uniformly applied to the liquid over the entire range of the reaction tank 1 by the low-speed rotation, the stirring effect is high, and the carrier 10 is floated and sufficiently mixed and contacted with the sewage sludge. Precipitation can be prevented. Therefore, a good sewage sludge treatment is performed.

In this low speed stirrer, since the lower blade 7 having a diameter smaller than the inner diameter of the draft tube 7 is used, the required power can be reduced to save energy.
The lower blade 6 and the upper blade 5 rotating at a low speed generate a low-speed flow in the processing liquid and float the carrier 10 added in the liquid, so that the carrier 10 is not worn or damaged by the flow. It is also possible to prevent the carrier to which the bacteria are adhered from being settled and becoming a compacted state and killing the bacteria.
In addition, the flow of the reverse direction can be given to the liquid in the draft tube 7 by reversing the rotating shaft 4 as needed.

FIG. 2 is a configuration diagram of a deep reaction tank of a support addition activated sludge method equipped with a low speed stirrer according to another embodiment of the present invention.
Here, the reaction tank 1 is deep, and a draft tube 7 extended corresponding to the depth of the reaction tank 1 is provided, but the drive unit 2 of the low-speed stirrer, the rotating shaft 4, the upper blade 5, and the lower blade 6. The configuration other than the equal draft tube 7 is the same as that of FIG.
When the rotating shaft 4 is rotated forward, a downward flow 11 in the vertical direction is given to the liquid in the draft tube 7 as in the case of FIG. 1, and the liquid flows out from the lower end of the draft tube 7. In this case, an upward flow 16 is generated. Therefore, even if the reaction vessel 1 is deep, good treatment is performed as in the case where the reaction vessel 1 is shallow.

The lower blade 6 and the upper blade 5 rotating at a low speed generate a low-speed flow in the processing liquid and float the carrier 10 added in the liquid, so that the carrier 10 is not worn or damaged by the flow. It is also possible to prevent the carrier to which the bacteria are adhered from being settled and becoming a compacted state and killing the bacteria.
This low-speed stirrer is low in cost because only the draft tube 7 is extended and the rotating shaft 4 and the drive unit 2 are not enlarged.

It is a block diagram of the reaction tank of the support | carrier addition activated sludge method provided with the low speed stirrer which is one Embodiment of this invention. It is a block diagram of the deep reaction tank of the support | carrier addition activated sludge process provided with the low speed stirrer which is other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reaction tank 2 Drive part 3 Coupling 4 Rotating shaft 5 Upper stage blade 6 Lower stage blade 7 Draft tube 8 Top plate 9 Side wall 10 Carrier 11 Downstream flow 12 Horizontal flow 13 Liquid surface 14 Bottom surface 16 Upstream flow 17 Mixed flow

Claims (3)

  A draft tube with its lower end located near the bottom is provided at the center of the reaction vessel, and a rotary shaft that rotates at a low speed from the drive unit installed on the top plate of the reaction vessel into the draft tube is suspended. A low-speed stirrer provided with a lower blade that gives a flow in a vertical direction to a liquid and an upper blade that gives a flow in a centrifugal direction to a liquid near the liquid surface.   The low-speed stirrer according to claim 1, wherein the lower blade and the upper blade float the carrier added in the liquid.   The low speed stirrer according to claim 1 or 2, wherein the reaction tank is a deep reaction tank.

Images