JP4813428B2 - Stirrer - Google Patents

Description

  The present invention relates to a stirrer, and in particular, in a stirrer in a sewage treatment tank, so as to reduce the frequency with which fibrous impurities such as hair get entangled with the stirrer blade and the stirrer is stopped due to overloading of the stirrer blade. The present invention relates to a stirrer with high contamination resistance.

  Conventionally, sewage flowing into a sewage treatment plant is guided into a sewage treatment tank and stirred by a stirrer disposed in the sewage treatment tank to perform an aerobic treatment. The aeration machine is not particularly limited. For example, a screw (stirring blade) disposed so as to be immersed in sewage is rotationally driven by a motor such as a motor to mix and stir the sewage.

However, in the sewage flowing into the sewage treatment tank, fibrous impurities such as hair are mixed together with the filth, and the fibrous impurities such as hair are entangled with the rotating stirring blade portion.
In particular, in the case where fibrous contaminants such as hair are present in the sewage to be stirred at a high concentration, the fibrous contaminants are easily entangled with the stirring blade, and the entanglement is increased to grow firmly.
When hair or the like is entangled with the stirring blade, the ability of the stirring blade to generate water flow decreases, and the stirring flow is caused by the flow of fluid generated from the outer periphery of the drive shaft toward the center due to the negative pressure generated in the drive shaft. A fibrous contaminant other than the contaminant entangled with the blade is further entangled with the drive shaft, and the amount of fibrous contaminant entangled with the stirring blade and the drive shaft increases. Flowed and the agitator stopped.

  In addition, when the stirrer is stopped due to overcurrent or the like when the fibrous contaminants are entangled with the stirring blades, it is necessary to remove the contaminants tightly entangled with the stirring blades in order to start operation again. Since the removal work is usually performed manually by an operator, the work efficiency is low, and there is a problem that if the occurrence frequency of the entanglement is high, the time for removing the foreign matter increases accordingly.

  In view of the problems of the conventional stirrer, the present invention stops the stirrer in the stirrer in the sewage treatment tank due to the overloading of the stirrer blade due to the entanglement of fibrous impurities such as hair on the stirrer blade part. An object of the present invention is to provide a stirrer having a high contamination resistance and a reduced frequency.

In order to achieve the above object, the stirrer of the present invention is provided with a stirring blade attached to the drive shaft driven by the prime mover at two positions above and below the driving shaft, and the outer periphery of the stirring blade is covered with an outer cylinder. The lower end of the outer cylinder covering the upper stirring blade and the upper end of the outer cylinder covering the lower stirring blade are formed in an expanded shape, and a rectifying mound is provided between them to form a suction port on the outer periphery, and the upper stirring met stirrer was outer cylinder lower end an outlet covering the stirring blade of the upper end and a lower outer cylinder covering the blade, the diameter of the upper stirring blade is smaller than the diameter of the stirring blade of the lower, larger pitch and it is characterized in that setting the forward coefficients of the both stirring blade to 0.3 or more and less than 0.9.

According to the stirrer of the present invention, impurities are less likely to get entangled with both the upper and lower stirring blades and the rotating portion on the outer periphery of the drive shaft, and the stirring operation can be performed smoothly over a long period of time .

  Moreover, the water flow generation | occurrence | production by a stirring blade can be ensured by arrange | positioning so that the outer periphery of a stirring blade may be covered with an outer cylinder.

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

Figure 1 shows a reference example of a stirrer.
Stirrer A This is for vertically at a predetermined position of the sewage treatment plant installed sewage treatment tank or water tank in such, this intended to be supported by or platform is free-standing in the bath, This is not particularly limited.
In addition, as shown in FIG. 1, the stirrer A is driven by a motor 1 disposed on the water surface with a drive shaft 2 having a stirring blade 3 attached to the lower end thereof. A predetermined distance is provided between the outer cylinder 4 and the outer cylinder 4 so as to cover the outer periphery, and the rectifying mound 7 is disposed above the outer cylinder 4 as necessary. .

The outer cylinder 4 has a trumpet shape with its upper end widened, sucks sewage in the tank from a suction port 41 formed in the outer peripheral portion of the widened upper end, and into the bottom layer from the discharge port 42 opened at the lower end. It forms so that it may discharge.
Accordingly, when the agitator A rotates the stirring blade 3 in the outer cylinder 4 via the drive shaft 2 by driving the motor 1, the agitator A removes sewage in the tank from the suction port 41 on the outer periphery of the upper end of the outer cylinder 4. After being sucked into 4 and stirred, the water flow generating force of the stirring blade 3 causes the water to be discharged toward the bottom layer of the sewage treatment tank through the discharge port 42 at the lower end. In this case, the rectifying mound 7 disposed above the outer cylinder allows the sewage sucked from the suction port to be smoothly guided to the discharge port through the outer cylinder 4.

  Further, when fibrous impurities such as hair are present in the sewage to be agitated, particularly at a high concentration, the fibrous impurities such as hair are entangled with the rotating stirring blade portion. This is because the loose part of the end of the contaminant (the end is divided into a plurality of parts) is temporarily stagnant on the inflow side of the blade part or the boss part of the stirring blade. After completing one round around the boss part of the stirring blade, the middle part of the foreign substance enters and joins between the divided end parts that are stagnant to form a ring, and the ring is connected to the core. As a result, the ring is tightly entangled by winding the contaminants multiple times, and the ring grows when the other contaminants are wound up. It becomes difficult.

If the advancing coefficient of the stirring blade is J, J can be expressed by the following equation.
J = V / (n · D)
Where V: Flow velocity (m / s)
n: rotational speed (rps)
D: Diameter of stirring blade (m)
When increasing the advance coefficient J a stirring blade to achieve the same flow rate ^{(≒ V × πD 2/4} ), the axial movement of the blade when rotated pitch (winding angle a "blade 360 of the blade ( Advance) Distance ") is increased and diameter D of the stirring blade is decreased.
As a result, the forward coefficient J can be increased, but the forward coefficient J also has an upper limit. When the pitch is increased in order to increase J, a stirring blade having an excessive pitch has problems in terms of performance such as cavitation. On the other hand, the diameter D is decreased to increase the forward coefficient J, but this also has a lower limit. The stirring blade has a boss having a diameter equal to or larger than the shaft diameter, and there is a lower limit of the ratio of the stirring blade diameter to the boss diameter. Judging comprehensively from these, the upper limit value of the forward coefficient J is 0.9.
When the stirring blade is rotated in a liquid in which hair of about several hundred millimeters is mixed by experiment, the advancing coefficient of the stirring blade that is difficult to get entangled with simulated hair or the like (however, the diameter is 300 mm or less) is 0.3 or more and 0.00. It was found to be less than 9.

Thus, by adopting a stirring blade with a large forward coefficient, it becomes difficult to combine the part where the ends of the foreign matter are loosened and the intermediate part (of the foreign substance) that has finished a round of the boss part of the stirring blade. The probability of entanglement with the stirring blade is significantly reduced.
In addition, the distance between the intermediate portion (of the contaminants) that has made one round of the boss portion and its original end portion has a large fluid flow rate in the axial direction with respect to the speed at which the drive shaft makes one revolution, and the drive shaft During the time of one rotation, the contaminant moves greatly in the axial direction together with the fluid. Even if the loose end of the loose hair group temporarily stagnates for a moment on the stirring blade inflow side, the intermediate portion after the same hair group has made a round makes a large distance in the axial direction from the end. Therefore, the probability of flowing in the axial direction without increasing the contact is increased.

Furthermore, since the diameter of the stirring blade is smaller than that of the axial flow rate, the stirring blade has a low probability of damming up impurities with the stirring blade, and the end of the hair becomes the stirring blade. The probability of staying temporarily for a moment is reduced.
The reason for the low probability of damming is that a stirring blade having a small diameter with respect to the flow velocity in a stirring blade that generates the same flow rate becomes a stirring blade having a large pitch of the stirring blades. That is, the wrapping angle of the blade has a large angle with the cross section perpendicular to the flow. Therefore, fibrous impurities such as hair existing on the stirring blade inflow side easily slip and flow on the outflow side due to the large inclination of the stirring blade, and hence the probability of staying is low.

FIG. 2 shows an embodiment of the stirrer of the present invention.
The agitator A is the drive shaft 2 driven by the motor 1 disposed above the water surface, a stirring blade 5 above side corresponding to the middle portion of the drive shaft 2, a lower stirring blade 3 to the lower end of the drive shaft 2 Attach it to the upper and lower two positions, and set a predetermined distance between the upper stirring blade 5 and the lower stirring blade 3 so that the outer cylinder 4 is fitted over the outer periphery. Constitute.

The outer cylinder 4 (4A, 4B) in the actual施例is two things one end in a trumpet shape having a shape diverging, together its open拡側as respectively accommodate the stirring blades 3, 5 therein The rectifying mounds 6 are stacked so as to be opposed to each other, and the rectifying mound 6 is sandwiched therebetween. The sewage is discharged upward from the upper discharge port 43 and discharged into the bottom layer from the discharge port 42.

Further, in the actual施例, coaxially mounting the two stirring blades 3 and 5, but with the direction of rotation the same, the water flow direction different directions, i.e., the water flow direction of the agitating blades 3 is downward, The twisting directions of the stirring blades are opposite to each other so that the water flow direction by the stirring blades 5 is upward.
In addition, by arranging the rectifying mound 7 above the upper discharge port 43, the sewage discharged from the upper discharge port 43 can be diffused in the water surface portion.

Therefore, in this embodiment, the two sets of upper and lower stirring blades 3 and 5 are coaxially wound in the opposite direction, so that the upward and downward flows are generated by the rotation of the drive shaft 2, and the stirring blade 5 The upper jet flow rate is set to be about 3/7 of the lower jet flow rate by the stirring blade 3.

The forward agitation coefficient of the lower agitating blade 3 is about 0.7, which is appropriate in terms of contamination resistance and performance, but the rotational speeds of the upper agitating blade 5 and the lower agitating blade 3 are structurally the same. Become.
In this structure, when the upper and lower jet flow ratio is designed to be up: down = 3: 7 (1: 2.3), the flow rate is set to about 3/7 with respect to the lower stirring blade. Although it is technically possible to reduce the value, the forward coefficient may be too small in some cases. Therefore, the diameter of the upper stirring blade 5 is made smaller than the diameter of the lower stirring blade 3 to suppress a decrease in the forward coefficient.
Thereby, the entanglement of the hair to the upper stirring blade 5 and the lower stirring blade 3 can be prevented.

When a coaxial stirring blade is used as a means for setting the ratio of the upper ejection flow rate and the lower ejection flow rate to 1: 2.3, if upper and lower stirring blades having the same diameter are used, the upper ejection side flow velocity is 1 On the other hand, the lower jet side flow velocity is 2.3. Comparing the forward coefficient of the upper and lower stirring blades in this case,
J = V / (n · D)
Therefore, the forward coefficient of the upper ejection stirring blade is 1 / 2.3 times the forward coefficient of the lower ejection stirring blade.
In this case, it becomes impossible for the upper and lower stirring blades to satisfy the condition that the forward coefficient is in the range of 0.3 or more and less than 0.9. Therefore, the stirring blade diameter on the upper ejection side with a small flow rate is relatively small, the pitch is designed to be larger than the above, and the stirring blade is such that the forward coefficient of both blades is 0.3 or more and less than 0.9. It shall be designed.

Although the agitator of the present invention have been described based on the example of its, the present invention is not limited to the configuration described in the embodiment described above, appropriately changed its configuration without departing from the scope and spirit thereof It is something that can be done.

  The stirrer of the present invention has the characteristic of reducing the frequency of stopping the stirrer due to the occurrence of overloading of the stirring blade due to the entanglement of the fibrous impurities to the stirring blade part, so that the stirring device in the sewage treatment tank For example, it can also be used for chemical machinery and food mixing applications.

It is a front longitudinal sectional view showing a reference example of 攪 agitator. It is a front longitudinal cross-sectional view which shows one Example of the stirrer of this invention.

DESCRIPTION OF SYMBOLS 1 Electric motor 2 Drive shaft 3 Lower stirring blade 4 Outer cylinder 5 Upper stirring blade 6 Commutation mound 7 Upper commutation mound

Claims (1)

A stirring blade is attached to the drive shaft driven by the prime mover at two positions above and below the driving shaft, and the outer periphery of the stirring blade is covered with an outer cylinder, and the lower end and lower side of the outer cylinder covering the upper stirring blade The upper end of the outer cylinder that covers the stirring blade is formed in an open shape, a rectifying mound is provided between them to form a suction port on the outer periphery, and the upper end of the outer cylinder that covers the upper stirring blade and the lower stirring blade are 0 lower end of the outer tube met outlet and the stirrer, the diameter of the upper stirring blade is smaller than the diameter of the stirring blade of the lower, and larger pitch, the forward coefficients of the both stirring blade covering A stirrer characterized by being set to 3 or more and less than 0.9.

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