JPS5826077Y2 - Aeration device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an apparatus for aerating a liquid by mixing a gas necessary for purification treatment of sewage or the like.

Conventionally, a pump has been used in this type of aeration device, and the method has been to suck in gas from a gas supply nozzle provided on the suction side of the pump, cause the gas to accompany the flow of liquid, and atomize the liquid inside the pump.

Generally, the average flow velocity in the pipe on the pump suction side is 1.5 to 2.5 m.
/s, and care has been taken to reduce the flow velocity in order to minimize the frictional resistance of the suction pipe.

In other words, even if gas is supplied at such a flow rate, it will not turn into fine bubbles at the time of supply, but will reach the impeller as air bubbles while being carried along with the water flow, and as they pass through the impeller. For the first time, the air bubbles become finer due to the rotation of the impeller.

However, devices that supply gas to the pump suction side for atomization have the following serious drawbacks.

As the water flow with air bubbles approaches the pump, it is subjected to the rotating action of the impeller, so the liquid, which is much denser than the gas, gathers on the inner surface of the pipe, and the air bubbles gather on the center side of the pipe, causing the pump to Before the bubbles pass through the rotary impeller inside the casing, the bubbles tend to coalesce at the center of the tube and form a bubble mass, and due to the tendency of the bubbles to pass through the center of the blade of the rotary impeller, they are not sufficiently refined. The disadvantage is that the air bubbles often block the impeller suction port, making it impossible for the impeller to suck in fluid.

The present invention prevents the above-mentioned drawbacks of conventional devices that aerate by supplying gas to the pump suction side, and provides an aeration device that can supply a larger amount of gas than before and more effectively miniaturizes bubbles. I'm trying.

In addition, in this invention, in order to dissolve oxygen in wastewater during wastewater treatment, the gas supply conduit is protruded from the inner surface of the casing.
The blowing tip of the gas supply conduit is placed near the suction end of the rotary impeller, and the gas-liquid contact is made fine by the two-stage turbulence action of the tube surface of the gas supply conduit and the turbulence action of the rotary impeller. The aim is to increase the area and extend the gas-liquid contact time, and also to provide an aeration device that significantly increases the gas dissolution rate through vigorous stirring.

The present invention is an aeration tank that produces a gas-liquid multiphase flow by supplying aeration agents such as air, oxygen, and ozone into the tank, and is equipped with a pump that produces a water flow such as a swirling flow or a circulation flow in the liquid in the tank. A rotary impeller is drivably disposed within the pump casing, and the outer circumferential end of the blade of the rotary impeller is disposed close to the inner surface of the casing, and the blowing tip of the gas supply conduit is connected to the suction end of the rotary impeller, that is, the suction end of the gas supply conduit. The gas supply conduit is arranged near the inlet end of the blade and at the outer peripheral end of the blade within the diameter of the impeller, facing the rotary impeller, and the gas supply conduit is connected to an aeration agent supply device for air, oxygen, ozone, etc. This is a unique aeration device.

The present invention will be described with reference to the drawings in terms of embodiments.
In the figure, a sewage treatment tank 3 is provided with a raw water pipe 1 and a treated water pipe 2, and a discharge pipe 5 whose open end extends to the bottom of the tank, and a discharge pipe 5 which extends above the open end of the discharge pipe 5 and below the liquid level 4. A suction pipe 6 with an open end is connected to a circulation pump 9 via a valve 7.8, and a gas supply conduit 10 is connected to the pump suction side via a valve 11 to prevent fine bubbles. By discharging the liquid from near the bottom of the tank along with the water flow, vertical, horizontal, and diagonal flows are formed in the wastewater in the sewage treatment tank 3, and a water flow such as a circulation flow or a swirling flow is generated in the liquid in the tank. This is intended to extend the gas-liquid contact time and to prevent suspended substances from accumulating at the bottom of the tank.

The circulation pump 9 has a rotating impeller 13 drivably arranged inside a casing 12 as shown in FIG. The air inlet of the gas supply conduit 10 is located near the suction end of the rotary impeller (i.e., the inlet end of the rotary impeller) and at the outer peripheral end of the blade within the diameter of the impeller 13, facing the rotary impeller 13. It is arranged.

With this configuration, it is possible to prevent the liquid flow from flowing backwards from the pressure side (impeller discharge side) to the negative pressure side (impeller suction side), and turbulent flow action and back turbulent flow action occur to reduce air bubbles. become

As for the gas inlet, it is also possible to have the gas inlet hole close to the side surface of the pipe as in the case of the conduit 10', or to connect the conduit 10' to the suction pipe 6 to open the conduit which is the gas inlet. It is also possible to have the tip of the impeller near the suction end of the impeller and close to the inner surface of the casing.

In the specific example shown in FIG. 3, an impeller 13 is provided below the liquid level 4 at the tip of a shaft 16 extending vertically inside the sewage treatment tank 3, and a trumpet pipe 14 is provided at the upper end of the casing 12 of the impeller 13. Further, a draft tube 15 whose tip extends to the bottom of the tank is connected to the lower end of the casing 12, and an aeration system is provided with a gas supply conduit 10 having a suction port near the suction end of the impeller 13 and near the inner surface of the casing. It's Toshide.

The details of the gas supply section are shown in FIG. 4, and the gas supply conduit may be a porous tube or may be blown in from the tip of the conduit 10', and the number of conduits may be selected as appropriate.

In either case, the gas supply conduit 10 has its inlet in the vicinity of the suction end of the rotary impeller (i.e., the inlet end) and at the outer peripheral end of the blade within the diameter of the impeller 13, as shown in FIG. It is arranged facing the car 13.

Therefore, the liquid flow can be prevented from flowing backward from the pressure side to the negative pressure side, turbulence action and back turbulence action occur, and the supplied gas is quickly atomized and at the same time is strongly stirred. The multiphase flow descends within the draft tube 15 over a sufficient residence time, reaches the bottom of the tank, and is discharged from the lower end of the draft tube 15, causing sewage in the sewage treatment tank 3 to flow vertically, horizontally, and diagonally. This creates a water flow such as a circulating flow or a swirling flow in the liquid in the tank.

In this case, the rotation speed is lower than that of a general pump impeller,
For example, even if the impeller circumferential speed is operated below lQm/s, the gas inlet is provided near the impeller suction end and near the inner surface of the casing within the impeller diameter, so the gas atomization effect is excellent and the pump It is possible to increase the gas dissolution rate even with less power than the rated power, and it is also possible to increase the dissolution efficiency.

The conduits 10, 10', 10'' are connected to an air supply source, such as a blower or an oxygen or ozone generator (not shown), for air supply.

In the specific example shown in FIG. 5, the casing 12 of the impeller 13
A gas supply conduit 10 is connected to the lower end of the trumpet pipe 14 and the upper end of the casing 12 to a draft tube whose tip extends below the liquid level 4, and has an inlet near the suction end of the impeller 13. The aeration device is provided as an aeration device (a configuration in which the third illustrated example is reversed), and a water flow such as a circulation flow or a swirling flow is generated in the tank liquid in the opposite direction to that of the third illustrated example.

Note that it is natural that the shorter the shaft 16 is, the higher the mechanical safety is, and the drive device 17 may be installed below the liquid level 4.

According to the present invention, the bubble miniaturization effect is large, and
Even when a larger amount of gas is supplied than conventionally, stable operation is possible, and aeration operations can be performed that can increase dissolution efficiency. (i.e., near the inlet end of the blade) and facing the rotary impeller at the outer circumferential end of the blade within the diameter of the impeller.
By applying a step action and supplying aeration agents such as air, oxygen, ozone, etc. from the blowing tip, the gas is supplied and receives the strong shearing action of the impeller, which reduces the effect of narrowing the bubbles. This is extremely large, especially since the position of the gas supply blows into the strong shear field of the flowing water near the inner surface of the casing where the impeller rotational speed is the highest, so the back of the collision surface between the conduit and the water flow becomes negative pressure, and the gas is supplied. A part of the gas is sucked into the back and the gas becomes finer due to the intense turbulent flow, and the dissolution rate of the gas is also significantly improved. In either case, the effects are the same, and it is possible to exhibit excellent aeration effects.

In addition, as mentioned above, the gas is atomized at the same time as it is supplied from the gas supply conduit, and is further subjected to a two-stage atomization action by the impeller, so the effect of atomization is greater than before. Moreover, as the gas is supplied, it is finely divided and subjected to a stronger stirring action, so the bubbles can be uniformly dispersed without locally aggregating, and the gas on the suction side of the pump can be There is no risk of blockage due to a lump.
In addition to being able to perform more stable aeration operations than conventional methods, it also has the effect of effectively demonstrating the aeration function, efficiently performing sewage purification treatment, and reducing the installation area of the treatment tank.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is an explanatory diagram of the system, FIG. 2 is a partially cutaway side view, FIG. 3 is an explanatory diagram of the system of another embodiment, and FIG. FIG. 5 is a diagram illustrating a system of another embodiment, and FIG. 6 is a partially cut side view of FIG. 5. 1... Raw water piping, 2... Piping, 3.
... Sewage treatment tank, 4 ... Liquid level, 5 ...
...Discharge pipe, 6...Suction pipe, 7,8...
...Valve, 9...Circulation pump, 10...
Gas supply conduit, 10'. 10″... Conduit, 11... Valve, 12.
...Casing, 13 ... Impeller, 14
...Trumpet tube, 15...Draft tube, 16...Shaft, 17...Driving device.

Claims (1)

[Scope of utility model registration request] An aeration tank that produces a gas-liquid multiphase flow by supplying an aeration agent such as air, oxygen, or ozone into the tank is equipped with a pump that generates a water flow such as a swirling flow or a circulating flow in the liquid in the tank, and a pump is installed inside the pump casing. A rotary impeller is provided so as to be drivable, and the outer circumferential end of the blade of the rotary impeller is disposed close to the inner surface of the casing, and the blowing tip of the gas supply conduit is placed near the suction end of the rotary impeller, that is, near the inlet end of the rotary impeller. and is arranged opposite to the rotary impeller at the outer peripheral end of the blade within the diameter of the impeller, and the gas supply conduit is connected to an aeration agent supply device for air, oxygen, ozone, etc. Device.