JP2015213886A - Agitation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an agitation device capable of fragmenting an aggregate of a liquid to be agitated, while suppressing the production of air bubbles.SOLUTION: An agitation device 100 comprises: a storage tank 10 for storing a liquid 1 to be agitated; a rotational driving device 20 for driving a revolving shaft 21 rotationally in the storage tank 10; a U-shaped bottom blade 30 disposed at the lower end of the revolving shaft 21; and a paddle blade 40 mounted on the revolving shaft 21 so that it may be positioned on the inner side of the U-shaped bottom blade 30. The paddle blade 40 has a liquid cutting plate 41 for establishing a shearing flow S.

Description

  The present invention relates to a stirring device including a stirring blade that is rotationally driven in a storage tank that stores a liquid to be stirred.

  Among the coating liquids, there are coating liquids having a property of being easily aggregated. For example, a catalyst slurry coating solution for CCM (Catalyst Coated Membrane) constituted by a catalyst layer and an electrolyte membrane in a fuel cell (FCV) is in a state in which carbon particles in the CCM catalyst are easily bonded to each other. Aggregates tend to form inside.

  When the agglomerates are mixed in the slurry coating solution, various problems such as, for example, a decrease in film formation quality, clogging of the coating jig, equipment failure, and an increase in viscosity occur.

  Therefore, it is necessary to make the coating liquid having the property of easily agglomerating finely by stirring the aggregate in the coating liquid. That is, the coating liquid is usually stored in a storage tank before the coating operation, and is stirred by rotating a stirring blade in the storage tank.

  As a technique related to the stirring device, for example, a stirring device that is rotationally driven in a bottomed cylindrical reaction tank and includes a U-shaped stirring blade that forms a vertical stirring flow is disclosed (Patent Document 1). reference). The U-shaped stirring blade has a bottom paddle, a pair of side paddles erected along the inner wall of the reaction tank, and a middle paddle disposed at the interface between the monomer phase and the aqueous phase.

JP 2011-178905 A

  By the way, in the structure of the U-shaped stirring blade of Patent Document 1, the stirring (shearing) effect of the coating liquid is still weak, and the aggregate cannot be subdivided. In addition, agitation turbulence due to aggregation of the coating liquid and turbulence due to high-speed agitation rotation occur, and bubbles are likely to be generated.

  This invention is made | formed in view of said situation, and it aims at providing the stirring apparatus which can subdivide the aggregate of a to-be-stirred liquid, suppressing generation | occurrence | production of a bubble.

  In order to achieve the above object, a stirring device according to the present invention includes a storage tank, a rotation drive device, a bottom blade, and a paddle blade. The storage tank contains a liquid to be stirred. The rotational drive device rotationally drives the rotational shaft in the storage tank. The bottom blade is formed in a U shape and is provided at the lower end of the rotating shaft. The paddle blade is provided on the rotating shaft so as to be positioned inside the U-shaped bottom blade. The paddle blade has a liquid draining plate for forming a shear flow.

  In the stirring device according to the present invention, a circulating flow is formed radially from the rotating shaft by the stirring of the U-shaped bottom blade that is rotationally driven. The circulating flow flowing down from the liquid level toward the bottom of the storage tank is sheared by the liquid draining plate of the paddle blade. Therefore, according to the stirring device according to the present invention, the aggregate of the liquid to be stirred can be subdivided by the shear flow formed by the liquid cutting plate of the paddle blade. Moreover, since the liquid draining plate of the paddle blade forms a shear flow, the bottom blade and the paddle blade can be rotated at a low speed. When the bottom blade and the paddle blade are rotated at a low speed, turbulent flow does not occur and generation of bubbles can be suppressed.

It is a schematic diagram of the whole structure of the stirring apparatus which concerns on this embodiment. FIG. 2A is a plan view of the bottom wing in this embodiment, and FIG. 2B is a front view. It is a figure where it uses for description of the aspect ratio of the bottom wing | blade in this embodiment. FIG. 4A is a plan view of a state in which a plurality of bottom blades are provided in the present embodiment, and FIG. 4B is a front view. It is a perspective view of a bottom wing and a paddle wing in this embodiment. FIG. 6A is a front view of a paddle blade in the present embodiment, and FIG. 6B is a plan view. It is a top view of the state which provided the paddle blade in this embodiment in multiple steps. It is a figure where it uses for description of the rake angle of the liquid cutting board in this embodiment. FIG. 9A is a front view of an example of the angle adjusting mechanism of the liquid cutting plate in the present embodiment, and FIG. 9B is a schematic diagram of the mounting base. Fig.10 (a) is a front view of the other example of the angle adjustment mechanism of the liquid cutting board in this embodiment, FIG.10 (b) is an AA arrow directional view. It is a schematic diagram of the liquid flow state by the stirring in the storage tank of the stirring apparatus which concerns on this embodiment. It is a schematic diagram of the liquid flow state of the liquid cutting board periphery in this embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. The dimensional ratios in the drawings are exaggerated for convenience of explanation, and are different from the actual ratios.

  First, with reference to FIG. 1 to FIG. 9, the configuration of the stirring device according to the present embodiment will be described. FIG. 1 is a schematic diagram of the overall structure of a stirring device according to this embodiment.

  As shown in FIG. 1, the stirrer 100 according to the present embodiment can be summarized as a storage tank 10 that stores the liquid to be stirred 1, a rotation drive device 20 that rotationally drives a rotary shaft 21 in the storage tank 10, and a rotation. A U-shaped bottom blade 30 provided at the lower end of the shaft 21 and a paddle blade 40 provided on the rotary shaft 21 so as to be positioned inside the U-shaped bottom blade 30 are provided. The paddle blade 40 has a liquid draining plate 41 for forming a shear flow. Details will be described below.

  The storage tank 10 stores the liquid to be stirred 1 to be stirred. Examples of the liquid to be stirred 1 include a slurry coating liquid having a property of being easily aggregated, such as a CCM catalyst slurry coating liquid.

  The storage tank 10 is a substantially bottomed cylindrical metal container. The bottom surface of the storage tank is formed in a curved surface or a spherical shape like a dish-shaped end plate shape.

  Examples of the constituent material of the storage tank 10 include austenitic stainless steel such as SUS316 and SUS304, but are not limited to the exemplified materials. The liquid contact portion of the storage tank 10 is preferably mirror-finished.

  When materials other than the exemplified materials are used as the constituent material of the storage tank 10, it is preferable to coat the wetted part with a synthetic resin having water repellency and solvent resistance such as polytetrafluoroethylene (PTFE). Surface treatment with a synthetic resin having water repellency and solvent resistance improves the slipperiness of liquid contact. In addition, it is effective in fixing and agglomerating the liquid and improving the cleaning property with a solvent.

  A disc-shaped lid 11 is provided at the opening of the storage tank 10 so as to be openable and closable. A rotation shaft 21 of the rotation drive device 20 is inserted through the center of the lid body 11. The connection of the rotary drive device 20 is preferably a structure capable of maintaining a hermetic seal between the rotary drive device 20 and the lid body 11, for example, a ferrule connection.

  Examples of the rotation drive device 20 include motors such as those manufactured by Unicontrols Corporation, Advantech Toyo Corporation, and Shinto Kagaku Corporation. The motor is not limited by electric drive or air drive. The coating solution is an organic solvent, and it is preferable to use an air drive motor in consideration of explosion protection.

  As a constituent material of the rotating shaft 21, for example, austenitic stainless steel such as SUS316 and SUS304 is preferable. Moreover, it is preferable that the surface of the rotating shaft 21 is mirror-finished.

  With reference to FIG. 2 to FIG. 4, the bottom blade in the present embodiment will be described. FIG. 2A is a plan view of the bottom wing in this embodiment, and FIG. 2B is a front view.

  As shown in FIGS. 2A and 2B, the bottom blade 30 has a U-shape when viewed from the front. An attachment base 31 for attaching the rotating shaft 21 is provided at the center of the U-shaped bottom blade 30. The mounting base 31 is substantially cylindrical and has an insertion hole 32 for inserting the lower end of the rotating shaft 21 at the center.

  A through hole 33 is formed in the peripheral wall of the mounting base 31 so as to reach the insertion hole 32. The through-holes 33 are opposed to each other in the direction perpendicular to the surface of the bottom blade 30 and are formed at two locations on the upper and lower sides. The rotary shaft 21 is tapped (not shown).

  By inserting the lower end of the rotating shaft 21 into the insertion hole 32 of the mounting base 31 and screwing a mounting bolt (not shown) into the tap portion of the rotating shaft 21 through the through hole 33 of the mounting base 31, the rotating shaft 21 is fitted. The bottom wing 30 is fixed. By directly fixing the bolts to the rotating shaft 21, it is possible to prevent the mounting bolts from dropping and to prevent foreign matter from entering the liquid feed pump (not shown).

  Alternatively, the bottom blade 30 can be fixed by not tapping the rotating shaft 21, forming a female thread portion on the mounting base 31, and screwing a set screw up to the rotating shaft 21. However, the fixing structure using the set screw may cause the set screw to fall, and there is a concern that the outer peripheral surface of the rotating shaft 21 may be damaged.

  The U-shaped bottom blade 30 is preferably as close as possible to the curved or spherical bottom surface of the tank 10 in order to wind up particles that settle on the bottom surface of the tank 10. In order to maintain the rotational movement of the bottom blade 30, it should not contact the bottom surface of the tank 10.

  As a constituent material of the bottom blade 30 including the mounting base 31, for example, austenitic stainless steel such as SUS316 and SUS304 is preferable. The surface of the U-shaped bottom blade 30 is preferably mirror-finished.

  Next, the aspect ratio of the cross-sectional shape of the bottom blade 30 will be described. FIG. 3 is a diagram for explaining the aspect ratio of the bottom blade in the present embodiment.

  As shown in FIG. 3, the aspect ratio of the cross-sectional shape of the bottom blade 30 is set such that the plate width A facing in the rotation direction is larger than the plate width B facing the wall surface of the storage tank 10 (A> B). Preferably it is. By setting the aspect ratio to A> B, a mixed stirring flow is generated that pushes up the particles that have settled on the bottom surface of the storage tank 10 with a U-shaped bottom blade surface.

  FIG. 4A is a plan view of a state in which a plurality of bottom blades are provided in the present embodiment, and FIG. 4B is a front view.

  As shown in FIGS. 4 (a) and 4 (b), a plurality of U-shaped bottom blades 30 may be attached to intersect with the lower end of the rotating shaft. In the example of FIGS. 4A and 4B, two U-shaped bottom wings 30 are provided so as to intersect in a cross shape at the center. The number of the bottom blades 30 is not limited, but it is preferable to arrange them at regular intervals in the rotation direction.

  With reference to FIGS. 5 to 10, the paddle blade 40 in the present embodiment will be described. FIG. 5 is a perspective view of the bottom blade and the paddle blade in the present embodiment. FIG. 6A is a front view of a paddle blade in the present embodiment, and FIG. 6B is a plan view.

  As shown in FIG. 5, the paddle blade 40 is provided on the rotating shaft 21 so as to be positioned inside the U-shaped bottom blade 30. The paddle blade 40 has a liquid draining plate 41 for forming a shear flow. The paddle blade 40 has a plurality of liquid cutting plates 41. In the paddle blade 40 of the present embodiment, for example, four liquid cutting plates 41 are arranged at equal intervals in the rotation direction, but the number of liquid cutting plates 41 is not limited to the illustrated number. As shown in FIG. 6B, the four liquid draining plates 41 are provided so as to cross in a cross shape at the central mounting base 42.

  The attachment base 42 is formed with an insertion hole 43 through which the rotary shaft 21 is inserted. A female thread 44 is formed on the peripheral wall of the mounting base 42 so as to reach the insertion hole 43. The female screw portions 44 are opposed to each other in the radial direction of the mounting base 42 and are formed at two locations on the upper and lower sides.

  The paddle blade 40 is fixed by inserting the rotary shaft 21 through the insertion hole 43 at the center of the mounting base 42 and screwing a set screw into the female screw portion 44 of the mounting base 42 until reaching the rotary shaft 21. Since the paddle blade 40 is fixed with the set screw, the height position of the paddle blade 40 on the rotating shaft 21 is variable. Alternatively, the paddle blade 40 is fixed by performing tapping (not shown) on the rotating shaft 21 and screwing the mounting bolt to the tap of the rotating shaft 21 through the through hole of the mounting base 42, as with the bottom blade 30. It may be done by.

  As shown in FIG. 6A, each liquid cutting plate 41 is attached with an inclination angle θ <b> 1 with respect to the rotational direction of the paddle blade 40. By providing each liquid cutting plate 41 with an inclination angle θ1 with respect to the rotation direction of the paddle blade 40, the paddle blade 40 is provided on the same rotating shaft 21, and the paddle blade 40 is the same as the bottom blade 30. Even at the rotational speed, the shearing force of each liquid cutting plate 41 is improved.

  As a constituent material of the paddle blade 40 including the mounting base 42, for example, austenitic stainless steel such as SUS316 and SUS304 is preferable. The surface of the U-shaped bottom blade 30 is preferably mirror-finished.

  FIG. 7 is a plan view showing a state in which a plurality of paddle blades are provided in the present embodiment. In FIG. 7, the mounting base is omitted.

  As shown in FIG. 7, the paddle blade 40 can be provided in a plurality of stages on the same rotating shaft 21. The plurality of paddle blades 40, 40 may be set so that the liquid draining plates 41 of each stage face the same direction. Alternatively, the liquid draining plates 41 at each stage may be arranged by shifting the angle θ2 (see FIG. 7). By shifting the angle θ2 of the liquid draining plate 41 at each stage, the shear effect can be made uniform throughout the entire storage tank 10, and the fragmentation effect of the aggregates can be improved. The shift angle θ2 between the plurality of paddle blades 40, 40 can be arbitrarily set.

  In the case where a plurality of paddle blades 40 are provided on the same rotating shaft 21, the plurality of paddle blades 40 may be disposed close to each other or may be disposed apart from each other in the axial direction. Although the height position of the paddle blade 40 of each stage can be set arbitrarily, it is preferable that the paddle blade 40 is disposed inside the U-shaped bottom blade 30. The paddle blade 40 of each stage can flexibly adjust the height position on the rotating shaft 21.

  FIG. 8 is a diagram for explaining the rake angle of the liquid draining plate in the present embodiment.

  As shown in FIG. 8, each liquid draining plate 41 has a rake angle θ <b> 3 on the front side in the rotational direction of the paddle blade 40. The rake angle θ3 may be inclined to the liquid surface side as shown in FIGS. 8A and 8B, and is inclined to the bottom surface side of the storage tank 10 as shown in FIGS. 8C and 8D. You may do it. In the drawings (a) and (c), a rake angle θ3 is formed only at the front end of the liquid cutting plate 41 in the rotation direction. In the drawings (b) and (d), a rake angle θ3 is formed over the entire width of the liquid cutting plate 41.

  FIG. 9A is a front view of an example of the angle adjusting mechanism of the liquid cutting plate in the present embodiment, and FIG. 9B is a side view of the shaft base portion.

  As shown in FIG. 9, the liquid draining plate 41 includes an angle adjusting mechanism 45. The angle adjusting mechanism 50 of the liquid cutting plate 41 includes an internal thread portion 44 formed on the mounting base 42, a bolt 46 fixed to the base portion of the liquid cutting plate 41, an adjustment nut 47 screwed to the bolt 46, Consists of The liquid draining plate 41 is attached to the rotary shaft by inserting the rotary shaft through the insertion hole 43 of the mounting base 42 and screwing the bolt 46 at the base of the liquid draining plate 41 into the female screw portion 44 of the mounting base 42. . The tilt angle θ1 can be adjusted by turning the adjustment nut 47 and fixing it at an arbitrary angle (see FIG. 6A).

  FIG. 10A is a front view of another example of the angle adjusting mechanism of the liquid cutting plate in the present embodiment, and FIG. 10B is a side view.

  An angle adjusting mechanism 45 shown in FIG. 10 includes a shaft 48 having a polygonal cross section fixed to the base of the liquid cutting plate 41 and a through-hole corresponding to the polygonal cross section of the shaft 48 formed on the peripheral wall of the mounting base 42. (Not shown). A shaft 48 having a polygonal cross section of the liquid cutting plate 41 is inserted into a through-hole having a polygonal cross section formed in the mounting base 42 at an arbitrary angle. For example, the shaft 48 is fixed by a pin or a retaining ring. The angle θ1 can be adjusted (see FIG. 6A).

  Next, with reference to FIGS. 1-12, the effect | action of the stirring apparatus which concerns on this embodiment is demonstrated. FIG. 11 is a schematic diagram of a liquid flow state by stirring in the storage tank of the stirring device according to the present embodiment. FIG. 12 is a schematic diagram of a liquid flow state around the liquid draining plate in the present embodiment.

  The stirrer 100 according to this embodiment is a stirrer suitable for stirring a liquid to be stirred such as a slurry coating liquid having a property of easily agglomerating. Examples of the slurry coating solution having the property of easily aggregating include a catalyst slurry coating solution for CCM. In the CCM catalyst, a Pt catalyst is supported on carbon particles, and the carbon particles are covered with an ionomer (electrolyte solution).

  Carbon is an active substance. Therefore, carbon tends to become an inert substance in order to stabilize energy. Carbon has a large surface area and a large active energy. Therefore, carbon combines with various substances in an attempt to reduce the surface area. Carbonized materials used for deodorants and the like use this property to adsorb odorous substances to carbon.

  In the case of a CCM catalyst, carbon is particles, and the carbon particles can move freely. Since carbon particles are light, they are very mobile. Moreover, in order to carry | support a Pt catalyst efficiently, the unevenness | corrugation is provided in the surface of the carbon particle, and the surface area is larger. From the above, since the carbon particles in the CCM catalyst are easily bonded to each other, the CCM catalyst slurry coating liquid is likely to aggregate.

  When the CCM catalyst slurry coating solution aggregates, various problems such as a decrease in film formation quality, clogging of the coating jig, failure of equipment, and an increase in viscosity occur as listed below.

  When the agglomerates are mixed in the slurry coating solution and applied as it is, a projection or a foreign substance appears on the film forming surface, resulting in a decrease in film formation quality such as a dent failure, a convex failure, or a foreign matter failure.

  If the agglomerates are mixed in the slurry coating solution and fed as it is, the coating jig is clogged and quality abnormalities are generated. For example, in the case of a slit die coater, agglomerates are clogged in the slit gap, resulting in defective ejection at the clogged portion and a streak failure of the coating film. In the case of inkjet coating, the inkjet nozzle is clogged with aggregates, resulting in ejection failure and dot missing failure. In the case of spray coating, agglomerates are clogged in the spray nozzle, resulting in ejection failure and diffusion failure, resulting in non-uniform film thickness.

  If the aggregates clog the pipe or the filter, the pumping pressure increases, causing equipment failure such as pump overload and wear of parts in the pump.

  Due to the occurrence of aggregation, the solid content increases and the viscosity increases. As a result, quality failures such as variations in coating film thickness occur.

  As shown in FIGS. 1 and 2, the stirring device 100 according to the present embodiment includes a U-shaped bottom blade 30. The U-shaped bottom blade 30 forms a circulating flow radially from the central portion in the vicinity of the rotary shaft 21 by the rotation of the rotary shaft 21. That is, as shown in FIG. 11, by rotation of the U-shaped bottom blade 30, the storage tank 10 goes from the center to the bottom, folds back at the bottom, rises along the wall surface, folds at the liquid level, and goes down to the center. Such a circulating flow C is generated.

  Further, as shown in FIG. 3, the aspect ratio of the cross-sectional shape of the bottom blade 30 is set such that the plate width A facing in the rotation direction is larger than the plate width B facing the wall surface of the storage tank 10 (A> B). Has been. By setting the aspect ratio to A> B, a mixed stirring flow is generated that pushes up the particles that have settled on the bottom surface of the storage tank 10 with a U-shaped bottom blade surface.

  Furthermore, as shown in FIG. 4, the effect of generating a mixed stirring flow is increased by attaching a plurality of U-shaped bottom blades 30 to the lower end of the rotating shaft.

  In addition, as shown in FIGS. 1, 5, and 6, the stirring device 100 according to the present embodiment has a paddle blade 40 at an intermediate portion of the rotary shaft 21 so as to be positioned inside the U-shaped bottom blade 30. Is provided. The paddle blade 40 has a liquid draining plate 41 for forming a shear flow. That is, as shown in FIG. 11, the liquid draining plate 41 of the paddle blade 40 shears the circulating flow from the liquid surface of the storage tank 10 to the bottom surface through the central portion. When the liquid cutting plate 41 of the paddle blade 40 forms the shear flow S, the aggregates in the coating liquid can be subdivided. Further, since the liquid cutting plate 41 of the paddle blade 40 forms the shear flow S, the bottom blade 30 and the paddle blade 40 can be rotated at a low speed. When the bottom blade 30 and the paddle blade 40 are rotated at a low speed, turbulent flow is not generated, and generation of bubbles can be suppressed.

  Further, as shown in FIG. 6A, the liquid draining plate 41 has an inclination angle θ <b> 1 with respect to the rotational direction of the paddle blade 40. As shown in FIG. 12, the shear force is improved by providing the liquid cutting plate 41 with the inclination angle θ1 with respect to the rotation direction R of the paddle blade 40. In addition, by providing the liquid cutting plate 41 with the inclination angle θ1, it is possible to suppress the generation of a resistance flow that causes a turbulent flow. Therefore, even if the bottom blade 30 and the paddle blade 40 are rotated at a low speed in a region where there is little risk of bubble generation, the same effect of agglomerating as in high-speed rotation can be obtained. Further, since the generation of resistance flow is suppressed, turbulent flow does not occur and generation of bubbles can be further suppressed.

  As shown in FIGS. 1 and 5 to 6, the paddle blade 40 is composed of a plurality of liquid cutting plates 41. By configuring the paddle blade 40 with a plurality of liquid cutting plates 41, the shearing effect of the slurry coating liquid is improved. Further, as shown in FIG. 7, the shear effect of the slurry coating liquid is also improved by providing a plurality of paddle blades 40 on the same rotating shaft 21.

  Furthermore, the height position of the rotary shaft 21 of the plurality of paddle blades 40 can be adjusted. By adjusting the height position of the paddle blade 40 on the rotating shaft 21, the shear effect can be flexibly applied regardless of the amount of liquid retained in the storage tank 10 and the liquid viscosity.

  As shown in FIG. 8, the liquid draining plate 41 has a rake angle θ <b> 3 on the front side in the rotational direction of the paddle blade 40. By having a rake angle on the front side in the rotation direction of the liquid cutting plate 41, the shearing force of the slurry coating liquid is improved. The liquid draining plate 41 can be rotated while the flow is stabilized without generating a turbulent flow with respect to the circulating flow. By rotating the liquid cutting plate 41 in the direction of the inclination angle θ1, the generation of bubbles can be suppressed.

  In addition, as shown in FIGS. 9 and 10, the liquid cutting plate 41 includes an angle adjusting mechanism 45 for adjusting the inclination angle θ <b> 1 of the liquid cutting plate 41. Since the inclination angle of the liquid cutting plate 41 for forming the shear flow S can be adjusted, the inclination angle θ1 can be changed depending on the liquid type, liquid viscosity, and liquid characteristics.

  The preferred embodiments of the present invention have been described above, but these are examples for explaining the present invention, and the scope of the present invention is not intended to be limited to these embodiments. The present invention can be implemented in various modes different from the above-described embodiments without departing from the gist thereof.

1 stirring liquid,
10 Reservoir,
20 rotary drive,
21 rotation axis,
30 Bottom wing,
40 paddle wings,
41 Draining board,
45 Angle adjustment mechanism,
θ1 tilt angle,
θ3 rake angle,
S shear flow,
100 Stirrer.

Claims (7)

A storage tank containing the liquid to be stirred;
A rotational drive device for rotationally driving the rotational shaft in the storage tank;
A U-shaped bottom wing provided at the lower end of the rotating shaft;
A paddle blade provided on the rotating shaft so as to be located inside the U-shaped bottom blade;
With
The paddle blade has a liquid draining plate for forming a shear flow.   The stirring device according to claim 1, wherein the liquid draining plate is disposed with an inclination angle with respect to a rotation direction of the paddle blade.   The stirring device according to claim 2, wherein the liquid draining plate includes an angle adjusting mechanism, and an inclination angle of the liquid draining plate is adjustable.   4. The stirring device according to claim 1, wherein the liquid draining plate has a rake angle on the front side in the rotational direction of the paddle blade. 5.   The stirring device according to any one of claims 1 to 4, wherein the paddle blade includes a plurality of liquid cutting plates.   The stirring device according to claim 5, wherein a plurality of paddle blades are provided on the same rotating shaft.   The stirring device according to any one of claims 1 to 6, wherein the paddle blade is attached such that a height position of the paddle blade is adjustable.