JPH0871583A - Air diffusing stirrer for reaction tank - Google Patents

Abstract

PURPOSE: To enhance the dissolving efficiency of oxygen into waste water by extending the moving distance of diffused air bubbles up to the surface of the water by rotating an air diffusing means along with the paddle blades arranged to the bottom part of a reaction tank to diffuse air. CONSTITUTION: A tubular rotary hollow shaft 116 is supported on the upper wall 122 provided at the central part of the upper opening of a reaction tank 110 in a rotatable manner by a shaft stand 124 and suspended toward the bottom part of the reaction tank 110. Upper and lower paddle blades 130, 132 are provided to the upper and lower positions of the rotary hollow shaft 116 suspended into the reaction tank 110 and rotated by a motor 120. Air pipes 136 are provided to the lower end opening of the rotary hollow shaft 116 along the lower paddle blades 132 so as to communicate therewith at one ends thereof. Air diffusing pipes 112 branched on both sides in a horizontal direction are provided to the air pipes 136 as air diffusion means and the stirring and aeration of waste water are performed at the same time by air bubbles blown out of air diffusion holes 112a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an agitating device for a reaction tank,
In particular, the present invention relates to improvement of a diffuser structure that improves the efficiency of oxygen supply to wastewater in a tank.

[0002]

2. Description of the Related Art As a method for removing organic substances from wastewater, an activated sludge method in which aerobic microorganisms oxidize and decompose is widely used. One of the most important points in the activated sludge method is how to efficiently supply oxygen in the air to the wastewater in the reaction tank. This is because the amount of dissolved oxygen in wastewater must be increased in order to promote biological reactions such as the oxidation of organic substances by microorganisms, the growth of microorganisms and autooxidation. Because it has a great influence on.

For this reason, conventionally, as shown in FIG. 5, an air diffuser is provided at the bottom of the reaction tank 10. The air diffuser sucks air from one end of the air diffuser 12 by the blower 14 through the intake pipe 13, blows bubbles from the air diffuser holes provided in the air diffuser 12, and supplies oxygen to the wastewater. Here, as a method of increasing the oxygen supply amount to the wastewater,
Since it suffices to increase the contact area between the bubbles from the diffuser holes and the waste water, diffuser pipes of various shapes have been conventionally considered. For example, a large porous diffuser plate or a grid-like diffuser pipe is provided at the bottom of the reaction tank 10. The method of arranging over a wide area is taken.

[0004]

However, the large-sized porous diffuser plate and the grid-like diffuser tube described above are themselves expensive, and the output of the blower for intake is large, resulting in high cost. There was a problem.

On the other hand, considering the oxygen supply amount per unit amount of bubbles blown out from the diffuser holes, the longer the residence time of the bubbles in the waste water, the more the dissolved oxygen amount increases.
However, in the conventional air diffuser, the bubbles blown out from the air diffuser rise almost upward as shown in FIG. That is, the air bubbles rise in the shortest distance from the diffuser holes shown in H ₁ of the figure to the water surface and the residence time becomes short, so that the oxygen dissolution efficiency was extremely low. As shown in FIG. 5, the reaction tank 10 is provided with a stirrer for mixing waste water and treated water, or for efficiently contacting flocs and carriers of microorganisms with waste water. There are also many. The stirrer rotates a rotating shaft 16 hanging down at the bottom of the reaction tank 10 with a motor 20, and stirs waste water by rotating a blade 18 fixed to the lower end of the rotating shaft 16.

Therefore, although the water flow generated by stirring the waste water may affect the upward movement of the bubbles blown out from the diffuser holes, the diffuser pipe 12 and the blades 18 are installed separately and the influence thereof is exerted. Is not constant, stirring the wastewater by the blades 18 does not always lengthen the retention time of the bubbles, and it is possible to improve the efficiency of dissolving oxygen in the wastewater simply by operating the air diffuser and the stirrer at the same time. I couldn't say. The present invention has been made to solve the above-mentioned problems of the prior art, and an object thereof is to provide a diffuser stirring device for a reaction tank, which is a small-sized diffuser and has a high oxygen supply efficiency to wastewater. is there.

[0007]

In order to achieve the above object, a diffuser agitator for a reaction tank according to the present invention comprises a rotary hollow shaft that hangs down to the bottom of the reaction tank, and the rotary hollow shaft. Air guiding means for guiding air into the shaft from the upper end to the lower end of the shaft, paddle blades arranged at the bottom of the reaction tank and rotated by the rotary hollow shaft, and provided along the paddle blades, It is characterized by comprising a ventilation pipe having a lower end opening of the hollow shaft communicating with each other, and an air diffusing means provided in the ventilation pipe and having an air diffusing hole.

[0008]

In the diffuser agitator for a reaction tank according to the present invention, as described above, the ventilation pipe is provided along the paddle blade, and the ventilation pipe is provided with the diffusion means having the diffusion holes. And the aeration means rotate integrally. Here, a large shearing force is generated near the surface of the paddle blade and the air diffusing means by the rotation. Therefore, in the wastewater above the paddle blades and the air diffusing means, a water flow obliquely upward, which is the opposite of the rotation direction, is generated, so that the bubbles blown out from the air diffusing holes do not rise right above, and are shown in FIG. Ascends diagonally upward.

That is, as is clear from the figure, the moving distance H ₂ of the bubbles from the air diffuser hole to the water surface is longer than the moving distance H ₁ when the bubbles as shown in FIG. Since the residence time in the waste water is long, the oxygen dissolution efficiency is extremely improved. In the case of performing anaerobic treatment by the aeration stirring device for the reaction tank, the air supply from the upper end opening of the rotary hollow shaft is stopped, and only the stirring by the paddle blade is performed without performing the air diffusion from the diffusion holes. To do.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration diagram of a diffuser / agitator for a reaction tank according to an embodiment of the present invention. FIG. 1 (A) is a top view and FIG. 1 (B) is a side view. In the diffuser stirring device shown in the figure, an upper wall 122 is bridged in the center of the upper opening of the reaction tank 110, and the headstock 1 is attached to the upper wall 122.
24 is fixed. A tubular rotary hollow shaft 116 is rotatably supported by the shaft base 124 via an upper bearing 126 and a lower bearing 128, and hangs down to the bottom of the reaction tank 110. In addition, the rotary hollow shaft 116
A motor 120 for applying a rotational driving force to the rotary hollow shaft 116 is installed on the upper end side of the.

Further, an upper paddle blade 130 and a lower paddle blade 132 are provided at two positions, an upper position and a lower position, of the rotary hollow shaft 116 that hangs in the reaction tank 110. Then, by driving the motor 120, the paddle blades 130, 1
32 is rotated and the waste water in the reaction tank 110 is stirred. On the other hand, an intake pipe 134 is connected to the upper end of the rotary hollow shaft 116, and air is introduced from the intake port of the intake pipe 134 into the shaft of the rotary hollow shaft 116 by a blower 114 installed in the intake pipe 134. Inhale. In addition, the rotary hollow shaft 116
A ventilation pipe 136 having one end communicating with the lower end opening is provided along the lower paddle blade 132. Further, as shown in FIG. 2 when viewed from the AA ′ direction in FIG. 2B, the ventilation pipe 136 has an air diffuser branched horizontally on both sides at the tip end side position of the lower paddle blade 132. An air diffuser 112 as a means is provided, and the air diffuser 112 is formed with an air diffuser hole 112a.

Therefore, when the rotary hollow shaft 116 is rotated, the air diffuser 112 rotates integrally with the lower paddle blades 132 while blowing the air sucked into the rotary hollow shaft 116 through the air diffuser holes 112a. It will be discharged, and stirring and aeration will be performed simultaneously. Here, as described above, when the lower paddle blade 132 and the air diffusing tube 112 rotate, a shearing force in an obliquely upward direction is generated around them, so that the air diffusing hole 112a is formed.
The bubbles blown out of the container also rise obliquely upward as shown in FIG. 4, and the residence time before reaching the water surface becomes extremely long.

As described above, in this embodiment, the air diffuser 112 having the air diffuser holes 112a is attached to the lower paddle blade 132.
And the lower paddle blades 132 are rotated integrally with the lower paddle blades 132 to diffuse air, so that it is possible to always secure a long moving distance of the diffused bubbles to the water surface, and the efficiency of dissolving oxygen in waste water. Therefore, it is possible to sufficiently supply oxygen even with a small air diffuser.

When the anaerobic treatment is performed in the diffuser stirring device, the blower 114 is not driven and the intake of air into the rotary hollow shaft 116 is stopped. Therefore, the waste water is not diffused from the air diffuser 112, and only the stirring is performed by rotating the paddle blades 130 and 132 while keeping the waste water in an anaerobic state. In the present embodiment, the upper paddle blade 130 and the lower paddle blade 132 are formed to have a diameter of 1/2 to 4/5 with respect to the inner width of the reaction tank.
The rotation speed is 5 to 15 rpm.

This is extremely large in size and low in rotation as compared with a conventional paddle blade, and by doing so, it is possible to destroy flocs of microorganisms and sponge-like porous carriers suspended in a tank. It is possible to satisfactorily agitate the entire wastewater. Also, by enlarging the lower paddle blade 132, the air diffuser 112 provided on the tip side thereof blows air bubbles while moving over a wide range, so that it is possible to further improve the oxygen dissolution efficiency in wastewater. Becomes Further, in this embodiment, the upper paddle blade 130 and the lower paddle blade 132 are formed in a twisted shape. That is, as shown in FIG. 3, the angle of inclination of the surfaces of the paddle blades 130 and 132 with respect to the horizontal direction is 45 degrees at the root (FIG. 3A) to 30 degrees at the tip (FIG. 3B). It is formed so that.

With such a shape, the upward flow velocities of the outer peripheral portion having a high linear velocity and the inner peripheral portion having a low linear velocity, and the moment force applied to each portion of the paddle blades are made uniform, whereby the stirring efficiency is improved. In addition, the direction of the shearing force acting on the tip side of the lower paddle blade 132 works so as to move the bubbles blown out from the diffuser holes 112a in a more oblique direction, so that the oxygen dissolution efficiency is further improved.

[0017]

As described above, according to the diffuser / stirrer for the reaction tank of the present invention, the diffuser is diffused while rotating together with the paddle blades, so that even the water surface of the diffused bubbles can be reached. It is possible to lengthen the moving distance of oxygen and improve the efficiency of oxygen dissolution in wastewater.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a schematic configuration of a diffuser stirring device for a reaction tank according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of the structure of a diffuser stirring device enlarged from the AA ′ direction shown in FIG.

FIG. 3 is an explanatory view of a shape of a paddle blade used in FIG.

FIG. 4 is an explanatory diagram of the trajectory of bubbles when the diffuser agitator for a reaction tank according to the present invention is used.

FIG. 5 is a structural explanatory view of a conventional air diffuser and stirring device.

FIG. 6 is an explanatory diagram of the trajectory of bubbles when a conventional air diffuser is used.

[Explanation of symbols]

 10, 110 ... Reaction tank 12, 112 ... Air diffuser 14, 114 ... Blower 16, 116 ... Rotating hollow shaft (rotating shaft) 18 ... Blade 20, 120 ... Motor 130 ... Upper paddle blade 132 ... Lower paddle blade 134 ... Intake pipe 136 ... Ventilation pipe

Claims (1)

[Claims] 1. A rotary hollow shaft that hangs down to the bottom of the reaction tank, an air guiding means that guides air into the rotary hollow shaft from an upper end opening to a lower opening, and the reaction tank bottom. A paddle blade that is disposed on the rotating hollow shaft and that rotates by the rotating hollow shaft; a ventilation pipe that is provided along the paddle blade and that communicates with a lower end opening of the rotating hollow shaft; and a ventilation hole that is provided in the ventilation pipe. An air diffuser for a reaction tank, comprising: an air diffuser.