Mixing device

Abstract

This solves the problems of conventional stirring devices. [Solution] The agitator 1 comprises a draft tube 3 installed in a water tank 10 and extending vertically, and a propeller 2 immersed in the water tank and creating a downward flow within the draft tube, the propeller being entirely submerged in water with its lower end positioned at or above the upper end of the draft tube.

Description

[Technical Field]

[0001] The technology disclosed herein relates to a stirring device. [Background technology]

[0002] Patent Document 1 describes a conventional sewage treatment device. This sewage treatment device includes an aeration tank, an agitator blade, and a draft tube. A carrier is present in the aeration tank. The carrier is porous or sponge-like, and bacterial cells are attached to the carrier. The draft tube is installed in the aeration tank and surrounds the agitator blade. The agitator blade generates a downward water flow within the draft tube. The draft tube guides the water flow to near the bottom wall of the aeration tank. The agitator blade and draft tube generate a circulating flow within the aeration tank.

[0003] The drive motor that rotates the agitator blade is installed outside the water tank, and the agitator blade is supported at the lower end of the agitator shaft connected to the motor. The length of the agitator shaft is limited because there is a high possibility that the free end of the agitator shaft will vibrate. Because the draft tube has the function of guiding the water flow close to the bottom wall of the aeration tank, conventional sewage treatment equipment can be applied to aeration tanks with deep water.

[0004] Patent Document 1 describes that the agitating blades must be located inside the draft tube. In addition, in the conventional sewage treatment device described in Patent Document 1, the distance between the upper end of the draft tube and the water surface is set to 1 / 5 or less of the water depth, and the distance between the lower end of the draft tube and the bottom wall of the aeration tank is set to 1 to 2.5 m. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5490491 Summary of the Invention [Problem to be solved by the invention]

[0006] As described in Patent Document 1, the specific gravity of the carrier is greater than 1, and therefore the carrier may deposit at the bottom of the water tank. FIG. 3 shows an example of a conventional agitator 100 installed in a water tank 10. The agitator 100 includes a propeller 2, which corresponds to an agitating blade, and a draft tube 3 that surrounds the propeller 2. Because the propeller 2 is located within the draft tube 3, the draft tube 3 has the function of regulating the flow of water flowing into the propeller 2 and the function of guiding the downward flow of water generated by the rotation of the propeller 2 to the bottom of the water tank 10.

[0007] Carriers 4 are deposited on the bottom wall 102 of the water tank 10. In a conventional water tank 10, the distance between the lower end of the draft tube 3 and the bottom wall 102 of the water tank 10 is relatively short so that the draft tube 3 can guide the flow to the bottom wall 102 of the water tank 10. Therefore, carriers 4 deposited on the bottom of the water tank 10 may block or slightly block the lower opening 32 of the draft tube 3 (hereinafter, these will be collectively referred to as "blocked"). When the lower opening 32 of the draft tube 3 is blocked, as indicated by a cross in FIG. 3 , water does not flow or flows poorly through the lower opening 32 of the draft tube 3. If water does not flow out from the lower end of the draft tube 3, the performance of the propeller 2 decreases, increasing the shaft power of the agitator 100 and potentially resulting in an overload or underload state. Furthermore, water does not flow into the draft tube 3 from the upper opening 31 of the draft tube 3, preventing the propeller 2 from generating a water flow. That is, agitator 100 cannot agitate water tank 10. Furthermore, because water does not flow inside draft tube 3, the state in which opening 32 at the lower end of draft tube 3 is blocked by carrier 4 cannot be resolved.

[0008] The technology disclosed herein overcomes the problems of conventional agitation devices. [Means for solving the problem]

[0009] The technology disclosed herein relates to a mixing device. a draft tube installed in the water tank and extending in the vertical direction; a propeller immersed in the water tank and creating a downward flow in the draft tube; The propeller is entirely submerged in water, and its lower end is located at the upper end of the draft tube or above the upper end.

[0010] This agitator differs significantly from conventional agitators in that the propeller is not located inside the draft tube.

[0011] When the propeller rotates, a downward current is generated. The downward current generated by the propeller flows into the draft tube through the opening at the top end, and the draft tube guides the downward current toward the bottom of the tub. Water flows out of the draft tube through the opening at the bottom end. The water flowing out of the opening at the bottom end of the draft tube generates a bottom-to-top current inside the tub, outside the draft tube. The propeller and draft tube generate a water current that circulates inside the tub.

[0012] Because the propeller is located outside the draft tube, water continues to flow into the propeller even if the opening at the bottom of the draft tube is blocked. The propeller can generate a water current in the water tank regardless of whether the opening at the bottom of the draft tube is open and water flows through the draft tube, or whether the opening at the bottom of the draft tube is blocked and water does not flow easily through the draft tube. This agitator can continue agitating the water tank while sending a water current to the opening at the top of the draft tube.

[0013] Furthermore, even if the opening at the lower end of the draft tube becomes blocked, the supply of water to the propeller continues, preventing the agitator from becoming overloaded or underloaded.

[0014] Furthermore, because at least a portion of the downward water flow generated by the rotation of the propeller flows into the draft tube from the upper opening, the lower opening of the draft tube is less likely to become clogged. Even if the lower opening of the draft tube becomes clogged, the downward water flow within the draft tube blows away any obstructions near the lower opening, such as carriers, thereby clearing the clog. The agitator can continue to agitate the water tank stably.

[0015] In addition, because the propeller is positioned at a height above the upper end of the draft tube, the length of the propeller shaft is shorter than when the propeller is positioned inside the draft tube. The above-mentioned propeller placement is also advantageous in terms of ensuring the support rigidity of the agitator shaft.

[0016] A distance L1 between the lower end of the propeller and the upper end of the draft tube may be set to 0≦L1≦D, where D is a diameter of the propeller.

[0017] If the bottom end of the propeller is too far away from the top end of the draft tube, the downward water flow generated by the rotation of the propeller will spread out in the radial direction of the propeller, weakening the water flow flowing into the draft tube from its upper opening. If 0≦L1≦D, the downward water flow generated by the rotation of the propeller will flow efficiently into the draft tube from its upper opening. This will stabilize the circulating flow within the tank.

[0018] The propeller may be positioned so that its axis of rotation is coaxial with the central axis of the draft tube.

[0019] If the rotational axis of the propeller and the central axis of the draft tube are coaxial, the downward water flow generated by the propeller will efficiently flow into the draft tube even if the propeller is located outside the draft tube. Note that the technology disclosed herein does not exclude structures in which the rotational axis of the propeller and the central axis of the draft tube are misaligned.

[0020] The inside diameter of the draft tube may be greater than the diameter of the propeller.

[0021] If the inside diameter of the draft tube is larger than the diameter of the propeller, the downward current of water generated by the propeller will flow efficiently into the draft tube.

[0022] The propeller may be an axial flow propeller. An axial flow propeller can generate a strong downward current along the central axis of the draft tube, and in combination with the draft tube, can efficiently generate a circulating current within the water tank.

[0023] A distance L2 between the lower end of the draft tube and the bottom surface of the water tank may be set to 0.3D≦L2≦2.0D.

[0024] If the lower end of the draft tube is too close to the bottom of the tank, the opening at the lower end of the draft tube is likely to be blocked by, for example, the carriers placed in the tank. On the other hand, if the lower end of the draft tube is too far from the bottom of the tank, the flow from the lower end of the draft tube will not reach the bottom of the tank, and the carriers will likely settle. If the distance L2 between the lower end of the draft tube and the bottom of the tank is 0.3D≦L2≦2.0D, blocking of the opening at the lower end of the draft tube is suppressed. Furthermore, the draft tube can direct the water flow close to the bottom of the tank.

[0025] When the propeller is stopped, carriers are deposited on the bottom of the water tank, A distance L3 between the lower end of the draft tube and the average interface of the carriers deposited on the bottom of the water tank may be set to 0.3D≦L3≦2.0D.

[0026] When carriers are deposited on the bottom of the water tank, if the lower end of the draft tube is too close to the interface of the carriers, the opening at the lower end of the draft tube is likely to become clogged. If the distance L3 between the lower end of the draft tube and the average interface of the carriers is 0.3D≦L3≦2.0D, the opening at the lower end of the draft tube is prevented from becoming clogged. The position of the average interface of the carriers can be estimated with high accuracy based on the amount of carriers added to the water tank and the size of the water tank. [Effects of the Invention]

[0027] The above-described agitator can stably agitate the water tank because the propeller is positioned outside the draft tube, allowing water to continue to flow into the propeller. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a cross-sectional view that schematically shows an agitation device installed in a water tank. [Figure 2] FIG. 2 is a cross-sectional view that schematically shows an agitator installed in a water tank into which a carrier has been placed. [Figure 3] FIG. 3 is a cross-sectional view schematically showing a conventional stirring device. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, an embodiment of the stirring device will be described with reference to the drawings. The stirring device described here is an example.

[0030] (Overall structure of the mixing device) 1 is a schematic diagram of an agitation device 1 installed in an aquarium 10. The aquarium 10 is, for example, a biological reactor. Note that the aquarium 10 is not limited to a tank for a specific purpose, and the agitation device 1 disclosed herein can be widely applied to various aquariums 10.

[0031] The agitator 1 generates a circulating water current in the water tank 10, thereby promoting water treatment. The water tank 10 has a side wall 101 and a bottom wall 102. The ceiling of the water tank 10 is open.

[0032] The agitator 1 is a vertical shaft type agitator equipped with a shaft 11 extending in the vertical direction. The agitator 1 is equipped with a propeller 2. The propeller 2 is supported at the lower end of the shaft 11. The propeller 2 is entirely submerged in water. The propeller 2 is an axial flow propeller, and generates a downward flow. The diameter of the propeller 2 is D.

[0033] The agitator 1 includes a motor 12. The motor 12 is a driving source that rotates the propeller 2. The motor 12 is located outside the water tank 10. The motor 12 is supported by a lid 103 that closes the opening of the water tank 10. The upper end of the shaft 11 is connected to the motor 12.

[0034] The agitator 1 includes a draft tube 3. The draft tube 3 is immersed in a water tank 10. The draft tube 3 extends in the vertical direction. The upper and lower ends of the draft tube 3 are both open. The central axis of the draft tube 3 is coaxial with the rotation axis of the propeller 2. The inner diameter D1 of the draft tube 3 is larger than the diameter D of the propeller 2 (i.e., D1>D). The cross section of the draft tube 3 may be circular or rectangular.

[0035] When the propeller 2 is rotated by the motor 12, a downward current is generated. The downward current generated by the propeller 2 flows into the draft tube 3 from the opening 31 at the upper end of the draft tube 3. The draft tube 3 guides the downward current toward the bottom wall 102 of the water tub 10. The water flows out of the draft tube 3 from the opening 32 at the lower end. The flow of water flowing out from the opening 32 at the lower end of the draft tube 3 generates a water current that flows from the bottom to the top between the draft tube 3 and the side wall 101 of the water tub 10. In this way, the propeller 2 and the draft tube 3, which are immersed in the water tub 10, generate a water current that circulates within the water tub 10 (see the open arrow in Figure 1).

[0036] The draft tube 3 guides the downward flow generated by the propeller 2 to the vicinity of the bottom wall 102 of the water tank 10. The draft tube 3 is particularly effective in a water tank 10 with a deep water depth. However, the draft tube 3 may also be installed in a water tank 10 with a shallow water depth. In other words, the agitator 1 disclosed herein can be applied to a water tank 10 with a shallow water depth.

[0037] (Characteristic arrangement of the stirring device) The lower end of the propeller 2 is located at the same position as or higher than the upper end of the draft tube 3. The distance L1 between the lower end of the propeller 2 and the upper end of the draft tube 3 is 0≦L1.

[0038] That is, in agitator 1, propeller 2 is located outside draft tube 3. Even if opening 32 at the lower end of draft tube 3 is blocked and the flow inside draft tube 3 is stagnated, water continues to flow into propeller 2, as shown by the open arrow in Figure 1. Propeller 2 can generate a water current in water tank 10, regardless of whether opening 32 at the lower end of draft tube 3 is open and water flows inside draft tube 3, or whether opening 32 at the lower end of draft tube 3 is blocked and water does not flow easily inside draft tube 3. Agitator 1 can continue agitating water tank 10.

[0039] Furthermore, since the propeller 2 is not located inside the draft tube 3, even if the opening 32 at the lower end of the draft tube 3 becomes blocked, the agitator 1 is prevented from becoming overloaded or underloaded.

[0040] A downward flow of water generated by the rotation of the propeller 2 flows into the draft tube 3 from the opening 31 at the upper end of the draft tube 3. The downward flow inside the draft tube 3 prevents the opening 32 at the lower end of the draft tube 3 from becoming blocked. Even if the opening 32 at the lower end of the draft tube 3 becomes slightly blocked, the downward flow inside the draft tube blows away any obstruction near the opening 32 at the lower end, thereby clearing the blockage at the opening 32 at the lower end of the draft tube 3. The agitator 1 can continue to agitate the water tank 10 stably.

[0041] Here, because the rotation axis of the propeller 2 and the central axis of the draft tube 3 are coaxial, even if the propeller 2 is located outside the draft tube 3, the downward water flow generated by the propeller 2 can efficiently flow into the draft tube 3. In addition, because the inner diameter D1 of the draft tube 3 is larger than the diameter D of the propeller 2, the downward water flow generated by the propeller 2 can efficiently flow into the draft tube 3.

[0042] Furthermore, in the agitator 1, the height position of the propeller 2 is at a position equal to or higher than the mouth 31 at the upper end of the draft tube 3, so the length of the shaft 11 of the propeller 2 is shorter than when the propeller 2 is located inside the draft tube 3. The agitator 1 makes it easy to ensure the support rigidity of the shaft 11, and the agitator 1 achieves stable operation.

[0043] The distance L1 between the lower end of the propeller 2 and the upper end of the draft tube 3 is limited to D or less. As mentioned above, D is the diameter of the propeller 2. The distance between the lower end of the propeller 2 and the upper end of the draft tube 3 is not too great. The downward water flow generated by the rotation of the propeller 2 efficiently flows into the draft tube 3 from the opening 31 at the upper end thereof, so the agitator 1 can stabilize the circulating flow within the water tank 10.

[0044] Here, the distance L4 between the propeller 2 and the water surface of the water tank 10 may be set so that the propeller 2 does not get too close to the water surface and take in air.

[0045] In the agitator 1, the distance L2 between the lower end of the draft tube 3 and the surface of the bottom wall 102 of the water tank 10 is 0.3D≦L2≦2.0D.

[0046] Draft tube 3 can guide the water flow up to near the surface of bottom wall 102 of water tub 10. Even if opening 32 at the lower end of draft tube 3 becomes blocked, the blockage can be cleared by operating propeller 2, so the lower end of draft tube 3 can be brought as close as possible to the surface of bottom wall 102 of water tub 10, which is advantageous for stirring the water throughout water tub 10. On the other hand, because the lower end of draft tube 3 is not too close to the surface of bottom wall 102 of water tub 10, blocking of opening 32 at the lower end of draft tube 3 is suppressed.

[0047] (Variation) 2 shows an example in which the carrier 4 is placed in the water tank 10. The carrier 4 is a granular porous material or a sponge, and has a specific gravity greater than 1. When the agitator 1 is stopped, the carrier 4 accumulates on the bottom wall 102 of the water tank 10.

[0048] The carriers 4 are introduced into the water tank 10 in an amount corresponding to the volume of the water tank 10. When the carriers 4 are piled up on the bottom wall 102 of the water tank 10, the average height L5 from the surface of the bottom wall 102 of the water tank 10 to the interface of the carriers 4, i.e., the upper surface of the piled up carriers 4, can be estimated with high accuracy based on the amount of carriers 4 introduced into the water tank 10 and the size of the water tank 10 (i.e., the length and width of the water tank 10).

[0049] When the carriers 4 are placed in the water tank 10, the distance L3 between the lower end of the draft tube 3 and the average interface of the carriers 4 is 0.3D≦L3≦2.0D.

[0050] When carriers 4 are deposited on the bottom of water tank 10, opening 32 at the lower end of draft tube 3 is likely to become clogged if the lower end of draft tube 3 is too close to the interface of carriers 4. If distance L3 between the lower end of draft tube 3 and the average interface of carriers 4 is 0.3D≦L3≦2.0D, opening 32 at the lower end of draft tube 3 is prevented from becoming clogged. Agitator 1 can operate stably while preventing opening 32 at the lower end of draft tube 3 from becoming clogged.

[0051] Even if the opening 32 at the lower end of the draft tube 3 becomes blocked, the propeller 2 can generate a water current in the water tank 10 as described above, and the agitator 1 can continue agitating the water in the water tank 10. Furthermore, the downward flow in the draft tube 3 generated by the driving of the propeller 2 blows away the carriers 4 near the opening 32 at the lower end, thereby clearing the blockage of the opening at the lower end of the draft tube 3.

[0052] 2, the distance L1 between the lower end of the propeller 2 and the upper end of the draft tube 3 satisfies 0≦L1≦D. The inner diameter D1 of the draft tube 3 is larger than the diameter D of the propeller 2 (i.e., D1>D). The central axis of the draft tube 3 is coaxial with the rotation axis of the propeller 2.

[0053] (Other variations) The central axis of the draft tube 3 does not necessarily have to be coaxial with the rotation axis of the propeller 2, and the central axis of the draft tube 3 may be offset from the rotation axis of the propeller 2. Furthermore, the central axis of the draft tube 3 may be offset from the rotation axis of the propeller 2, as long as the area of ​​the propeller 2 projected onto the draft tube 3 falls within the inner diameter of the draft tube 3. Furthermore, the diameter of the draft tube 3 may be enlarged upward near the upper end of the draft tube 3 with respect to the main inner diameter of the draft tube 3, so that the inner diameter D1 at the upper end is greater than D.

[0054] Positioning the propeller 2 outside the draft tube 3, as in the agitator 1 disclosed herein, can also be applied, for example, to cases where a draft tube 3 is installed later in a water tank that does not already have a draft tube 3 installed. Even if a draft tube 3 is installed later in a water tank, the propeller 2 is not located inside the draft tube 3, so the draft tube 3 does not adversely affect the performance of the existing propeller 2. Therefore, the draft tube 3 can be installed later in a water tank without changing the existing propeller 2 and motor 12. The draft tube 3 installed later in a water tank allows the agitator to achieve stable agitation of the water tank. [Explanation of symbols]

[0055] 1. Stirring device 10. Aquarium 2 propellers 3 Draft tube 4. Carriers

Claims

1. a draft tube installed in the water tank and extending in the vertical direction; a propeller immersed in the water tank and creating a downward flow in the draft tube; The propeller is entirely submerged in water, and its lower end is located at the upper end of the draft tube or above the upper end. Stirring device.

2. The stirring device according to claim 1, The distance L1 between the lower end of the propeller and the upper end of the draft tube is 0≦L1≦D, where D is the diameter of the propeller. Stirring device.

3. The stirring device according to claim 1, The propeller is positioned so that its rotation axis is coaxial with the central axis of the draft tube. Stirring device.

4. The stirring device according to any one of claims 1 to 3, The inner diameter of the draft tube is larger than the diameter of the propeller. Stirring device.

5. The stirring device according to claim 1, The propeller is an axial flow propeller. Stirring device.

6. The stirring device according to claim 1, The distance L2 between the lower end of the draft tube and the bottom surface of the water tank is 0.3D≦L2≦2.0D. Stirring device.

7. The stirring device according to claim 6, When the propeller is stopped, carriers are deposited on the bottom of the water tank, The distance L3 between the lower end of the draft tube and the average interface of the carrier deposited on the bottom of the water tank is 0.3D≦L3≦2.0D. Stirring device.

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