JP6835487B2 - Stirrer - Google Patents

Description

The present invention relates to a stirrer.

As a stirring device that stirs while adjusting the temperature of the object to be agitated by exchanging heat, a heat transfer coil is arranged in the stirring tank for the purpose of improving the heat transfer characteristics, and the power to the heat transfer coil is adjusted to be covered. Those that control the temperature rise rate of the agitated material (see, for example, Patent Document 1), those that arrange a heat source outside the agitating tank and adjust the temperature of the agitated object inside via the agitating tank (for example, Patent Document 2). 3, 3) is disclosed. Further, as a stirring device for forcibly stirring the material to be agitated for the purpose of making the temperature of the material to be agitated uniform, a device provided with a baffle (jamming plate) in the stirring tank (see, for example, Patent Documents 4 and 5) has been proposed. Has been done.

Of these, the one in which the heat transfer coil is arranged is excellent in temperature control ability by direct heat transfer, and the one in which the heat source is arranged outside the stirring tank is excellent in the capacity of the object to be agitated in the stirring tank. .. In addition, if a baffle is provided in the stirring tank, the reaction product generated by the reaction of the material to be stirred and the generated thermal energy are diffused to suppress the temperature and concentration unevenness of the material to be stirred in the stirring tank. It is excellent in that it can be done.

Japanese Unexamined Patent Publication No. 2001-224951 Japanese Patent No. 5220544 Japanese Patent No. 5249419 Japanese Unexamined Patent Publication No. 2009-18274 Japanese Unexamined Patent Publication No. 2013-151621

However, among the above-mentioned stirring devices, those in which the heat transfer coil is arranged have a limitation in the size of the stirring blade in order to avoid physical contact with the heat transfer coil, or the object to be agitated stays in the vicinity of the heat transfer coil. This causes uneven temperature and concentration, and there is a problem that the combination of the object to be agitated and the heat transfer coil is restricted in order to prevent corrosion (oxidation deterioration, etc.) of the heat transfer coil.

In addition, if the heat source is placed outside the stirring tank, the heat transfer efficiency tends to decrease as the stirring tank is scaled up, which requires a high-capacity heat source and takes time to control the temperature. There are drawbacks. Further, in the case where the baffle is provided in the stirring tank, it is expected that the concentration and temperature distribution will be uniform and the unreacted part will be reduced, but there is a possibility that the stagnant part of the material to be agitated is locally generated on the back surface of the baffle. In addition, since the baffle is provided, it tends to be an obstacle to the free shape selection of the stirring blade.

The present invention has been made based on the above circumstances, and an object of the present invention is to be able to quickly and surely adjust the temperature of the agitated object and to make the temperature and concentration of the agitated object uniform. It is an object of the present invention to provide an excellent stirring device.

The present invention
(1) A stirring device that stirs an object to be agitated while adjusting the temperature.
A stirring tank that houses the material to be agitated and
A temperature control means provided outside the stirring tank and adjusting the temperature of the object to be stirred via the stirring tank.
A stirring blade arranged in the stirring tank and stirring the object to be agitated while rotating,
It is connected to the stirring blade via a stirring shaft and includes a driving means for rotationally driving the stirring blade.
A stirring device, characterized in that at least a part of the inner wall of the stirring tank is formed in a predetermined uneven shape.
(2) The stirring device according to (1) above, wherein the surface area of the inner wall of the stirring tank is more than 1.1 times the surface area of the virtual inner wall assuming that the inner wall is flat.
(3) The stirring device according to (1) or (2) above, wherein the roughness of at least a part of the inner wall of the stirring tank is 1.0 μm or less in arithmetic average roughness (Ra).
(4) The stirring device according to any one of (1) to (3) above, wherein the uneven shape is periodically formed in the stirring axis direction.
(5) The stirring device according to (4) above, wherein the height difference between the concave portion and the convex portion in the concave-convex shape is 10 mm or more and 40 mm or less, and the period of the concave-convex shape is 100 mm or more.
(6) In the projected image when the stirring tank is projected on the projection plane orthogonal to the stirring axis, the minimum value of the dimension between the inner walls crossing the stirring axis is the maximum height difference between the concave portion and the convex portion in the concave-convex shape. The stirring device according to any one of (1) to (5) above, which is more than four times the value.
(7) The shape of the concave portion and the convex portion in the concave-convex shape includes a part of at least one shape selected from the group consisting of a spherical shape, an ellipsoidal surface shape, a conical surface shape, and a polygonal pyramid surface shape. The stirring device according to any one of (1) to (6) and (8) the stirring tank are made of a metal material containing stainless steel, copper or aluminum as a main component, from (1) to (1). 7) The stirring device according to any one of the items.

In the present specification, the "inner wall" means the surface of the body surface of the stirring tank that comes into contact with the material to be agitated. Further, the "height difference between the concave portion and the convex portion" means the distance between the convex portion (top portion) and the concave portion (lowest portion) in the direction perpendicular to the inner wall in the adjacent concave portion and convex portion. Further, the "predetermined uneven shape" means a predetermined uneven shape having a specific period, and the "roughness of the inner wall" means the shape of an irregularly formed inner wall. The above-mentioned predetermined uneven shape and the roughness of the inner wall are different concepts.

According to the present invention, the area of contact with the agitated object on the inner wall of the agitating tank can be increased, the temperature of the agitated object can be adjusted quickly and surely, and turbulence due to the uneven shape is generated. It is possible to promote the disturbance of the material to be agitated, and it is possible to provide a stirring device excellent in uniforming the temperature and concentration of the material to be agitated.

It is the schematic sectional drawing which shows the 1st Embodiment of this invention. It is a schematic view which shows the uneven shape of the inner wall of the stirring tank of FIG. 1, (a) is the perspective view of a part cut out of the stirring tank, (b) is the perspective view near the end face of (a), (c). Is a figure showing a part of the outline of the end face of (b). It is the schematic which shows the outline of the inner wall of the stirring tank of FIG. 1 enlarged. It is a schematic sectional drawing which shows the 2nd Embodiment of this invention. It is a schematic sectional drawing which shows the 3rd Embodiment of this invention. It is the schematic sectional drawing which shows the comparative example. 1 is a schematic cross-sectional view for explaining the dimensions of each part of FIGS. 1 and 4 to 5.

The stirring device of the present invention is a stirring device that stirs an object to be agitated while adjusting the temperature, and includes a stirring tank for accommodating the object to be agitated inside and a stirring tank provided outside the stirring tank. A temperature control means for adjusting the temperature of the object to be agitated, a stirring blade arranged in the stirring tank and stirring the object to be agitated while rotating, and a stirring blade connected to the stirring blade via a stirring shaft. The stirring blade is provided with a driving means for rotationally driving the stirring blade, and at least a part of the inner wall of the stirring tank is formed in a predetermined uneven shape.

Hereinafter, the first to third embodiments of the present invention will be described with reference to FIGS. 1 to 5, but the present invention is not limited to the embodiments described in the drawings.

[First Embodiment]
FIG. 1 is a schematic cross-sectional view showing a first embodiment of the present invention. As shown in FIG. 1, the stirring device 11 is roughly composed of a stirring tank 21, a temperature control means 5, a stirring blade 3, and a driving means 8.

The stirring tank 21 houses the object to be agitated b inside. Specifically, the stirring tank 21 has a substantially cylindrical body portion 21a and a substantially semi-rotating ellipsoidal surface-shaped tank bottom portion 21b connected so as to close one end of the body portion 21a. ..

In the stirring tank 21, the inner wall 61 (hereinafter, also referred to as “contacting portion”) that comes into contact with the object to be agitated b of the stirring tank 21 is at least a part of the inner wall 61 of the stirring tank 21 (in the present embodiment, the inner wall 61). The entire wetted portion of the above) is formed in a predetermined uneven shape 61a.

More specifically, the concave-convex shape 61a is a shape in which the respective shapes of the concave portion 61b and the convex portion 61c in the concave-convex shape 61a include a part of the spherical shape, that is, stirring as shown in FIGS. 1 and 2. The contour of the wetted portion side in the cross section of the tank 21 is formed in a mountain valley shape so as to be curved, and the uneven shape 61a is periodically formed in the four directions of the stirring shaft. By periodically forming the concave-convex shape 61a in the four directions of the stirring shaft in this way, the temperature of the object to be agitated b can be effectively adjusted, and the inner wall of the stirring tank 21 can be easily formed. Can be done. The portion where the uneven shape 61a is formed may be a part of the wetted portion, but from the viewpoint of promoting heat transfer and improving the uniformity of temperature and concentration, the wetted portion is as in the present embodiment. It is preferably the whole.

Here, the uneven shape 61a of the inner wall 61 of the stirring tank 21 can be defined by the height difference 7a and the period length 7b, as shown in FIG. The ratio between the height difference 7a and the period length 7b is not particularly limited, but from the viewpoint of improving the degree of freedom in the shape of the stirring blade 3 (described later), the relationship represented by the following equation (1) is established. It is preferable to satisfy, and it is more preferable to satisfy the relationship represented by the following formula (2).
(7b / 4)> (7a / 2) (1)
(7b / 2)> (7a / 2) (2)

Further, the height difference between the concave portion 61b and the convex portion 61c in the concave-convex shape 61a is preferably 10 mm or more and 40 mm or less, and more preferably 20 mm or more and 30 mm or less from the viewpoint of improving the degree of freedom in the shape of the stirring blade 3 as in the above ratio. Further, the period of the concave-convex shape 61a is preferably 100 mm or more, more preferably 150 mm or more, from the viewpoint of improving ease of manufacturing, to efficiently generate turbulent flow and secure a sufficient wetted area to improve heat transfer. From the viewpoint, 300 mm or less is preferable, and 200 mm or less is more preferable.

As a method for forming the uneven shape 61a, for example, methods such as machining, etching, casting, forging, welding, polishing, metallurgy, punched sheet metal, punched sheet metal, and die forming press may be used alone or in combination. Can be done.

Further, as shown in FIG. 3, it is preferable that the roughness of at least a part of the inner wall 61 of the stirring tank 21 is 1.0 μm or less in terms of arithmetic mean roughness (Ra). As a result, it is possible to prevent dust from getting caught in the inner wall, and it is possible to suppress adhesion of dirt to the inner wall 61 of the stirring tank 21.

As a method of forming the inner wall 61 having the above roughness, for example, a method of performing chemical polishing by electrolytic polishing, plating, etching or the like; a method of polishing by a grindstone, a buff or the like; physical by sandpaper processing, laser processing or the like. Examples include a method of polishing and a method of combining these. The inner wall having a roughness of Ra of 1.0 μm or less can be obtained by, for example, polishing with an abrasive having a particle size equivalent to P400 specified in JIS R 6010 and then performing electrolytic polishing. it can.

Here, the surface area of the inner wall 61 of the stirring tank 21 is preferably more than 1.1 times, more preferably more than 1.5 times, the surface area of the virtual inner wall when the inner wall 61 is assumed to be flat. It is preferable, and more preferably more than twice. As a result, the temperature of the object to be agitated b can be adjusted more quickly and reliably.

Further, in the projected image when the stirring tank 21 is projected on the projection plane orthogonal to the stirring shaft 4, the minimum value of the dimensions between the inner walls 61 crossing the stirring shaft 4 is the concave portion 61b and the convex portion 61c in the concave-convex shape 61a. It is preferable that the height difference is more than 4 times the maximum value of. As a result, the space in which the stirring blade 3 can be arranged can be widened, and the degree of freedom in the shape of the stirring blade 3 can be improved.

The temperature control means 5 is provided outside the stirring tank 21 and adjusts the temperature of the object to be agitated b via the stirring tank 21. The temperature controlling means 5 is not particularly limited as long as the stirring tank 21 can be heated and cooled, and for example, a jacket, a rubber heater, a Peltier element, or the like can be adopted. When the temperature is adjusted from the outer circumference of the stirring tank 21 by using a jacket or the like, at least the surface of the outer circumference of the stirring tank 21 in contact with the jacket or the like is formed into a shape such as the above-mentioned predetermined uneven shape. Therefore, it is preferable to make the heat transfer area (contact area between the jacket or the like and the stirring tank) as wide as possible. As a result, heat transfer between the jacket or the like and the stirring tank 21 can be promoted.

A jacket 51 is adopted as the temperature control means 5 of the present embodiment. Specifically, as shown in FIG. 1, the jacket 51 is spirally wound around the outer periphery of the stirring tank 21, a flow path 52 is provided inside the jacket 51, and the heat medium c is the jacket 51. It is introduced into the flow path 52 through the inlet 53 located below, and is located above the jacket 51 after heat exchange (heating or cooling the agitated object b) with the agitated object b while flowing through the flow path 52. It is discharged from the outlet 54.

The heat medium c may be either a disposable fluid (such as hydrogen peroxide) or a reusable fluid (such as circulating water) as long as the temperature at the inlet 53 is constant. As the heat medium c, glycols such as ethylene glycol and propylene glycol, water, salt water, silicone oil, hot air, and steam can be preferably used from the viewpoint of preventing corrosion deterioration of the flow path 52 and the like. These may be used alone or in combination.

The flow velocity of the heat medium c is preferably 0.3 m / sec to 3.0 m / sec, more preferably 1.0 m / sec to 2.0 m / sec, from the viewpoint of improving heat transferability. .. The direction of flow of the heat medium c in the flow path 52 is not particularly limited, but is preferably the direction opposite to the rotation direction of the stirring blade 3 from the viewpoint of efficient heat exchange. Further, from the viewpoint of improving the filling property of the heat medium c in the flow path 52, it is also preferable that the heat medium c flows from the lower side (inlet 53) to the upper side (outlet 54) of the stirring tank 21.

The stirring blade 3 is arranged in the stirring tank 21 and stirs the object to be agitated b while rotating. The stirring blade 3 is used to mix the material b to be agitated (mixing, stirring, dispersion, etc. are collectively referred to as "mixing"), to make the concentration distribution uniform, and to transfer the temperature control means 5 to the material b to be agitated. Promotes heat. The stirring blade 3 is a plate-shaped member, and is vertically fixed to one end side of the stirring shaft 4 for propagating the power of the driving means 8 described later. The driving means 8 is connected to the stirring blade 3 via the stirring shaft 4 and rotationally drives the stirring blade 3. As the drive means 8, for example, the motor 81 shown in FIG. 1 or the like can be adopted.

The material constituting the stirring tank 21, the stirring blade 3, and the stirring shaft 4 is not particularly limited, and for example, a metal-based material such as stainless steel, iron, copper, brass, aluminum, or cemented carbide may be used. it can. Among these, the stirring tank 21 is preferably formed of a metal material containing stainless steel, copper or aluminum as a main component. As a result, heat transfer of the stirring tank 21 itself can be promoted, and the temperature of the object to be agitated b can be adjusted more quickly.

Further, in the wetted portions of the stirring tank 21, the stirring blade 3 and the stirring shaft 4, white alumina, gray alumina, alumina-titania, alumina-magnesia, zirconia-calcia, zirconia-yttria, etc. are provided on the surfaces of the metal-based materials. Surface-treated ceramics such as zirconia-magnesia, chromia-titania, chromia-silica-titania, tungsten, titania, chromia, yttria, zirconia, chrome carbide, magnesia, ceria, tungsten carbide, and fluorine-based A material lined or the like may be adopted.

As described above, in the present embodiment, the above-mentioned stirring tank 21, temperature controlling means 5, stirring blade 3 and driving means 8 are provided, and at least a part of the inner wall 61 of the stirring tank 21 is formed in the concave-convex shape 61a. Therefore, the area of contact with the agitated object b on the inner wall 61 of the agitating tank can be increased, the temperature of the agitated object b can be adjusted quickly and surely, and the turbulent flow caused by the uneven shape 61a. The disturbance of the agitated object b can be promoted by the generation of the agitated object b, and the temperature and the concentration of the agitated object b are excellently made uniform.

[Second Embodiment]
FIG. 4 is a schematic cross-sectional view showing a second embodiment of the present invention. As shown in FIG. 4, the stirring device 12 is roughly composed of a stirring tank 22, a temperature control means 5, a stirring blade 3, and a driving means 8. In the second embodiment, the uneven shape 62a of the wetted portion of the inner wall 62 of the stirring tank 22 is different from that of the first embodiment. Since the temperature control means 5, the stirring blade 3, and the driving means 8 have the same configuration as those of the first embodiment, the same parts are designated by the same reference numerals and detailed description thereof will be omitted.

In the present embodiment, as shown in FIG. 4, the concave-convex shape 62a of the wetted portion on the inner wall 62 of the stirring tank 22 has a triangular pyramid shape, respectively, of the concave portion 62b and the convex portion 62c in the concave-convex shape 62a. The shape including the portion, that is, the contour on the wetted portion side in the cross section of the stirring tank 22 is formed in a mountain valley shape so as to be a polygonal line, and the uneven shape 62a is periodically formed in the four directions of the stirring shaft. Has been done.

As described above, in the present embodiment, the contour of the wetted portion side in the cross section of the stirring tank 22 is formed in a mountain valley shape so as to be a polygonal line. Therefore, in addition to the effect of the first embodiment described above, the stirring tank The inner wall 62 of 22 can be easily formed. The portion where the concave-convex shape 62a is formed may be a part of the wetted portion, but from the viewpoint of promoting heat transfer and making the temperature and concentration uniform, the entire wetted portion as in the present embodiment. Is preferable.

[Third Embodiment]
FIG. 5 is a schematic cross-sectional view showing a third embodiment of the present invention. As shown in FIG. 5, the stirring device 13 is roughly composed of a stirring tank 23, a temperature control means 5, a stirring blade 3, and a driving means 8. In the third embodiment, the height difference between the concave portion 63b and the convex portion 63c in the concave-convex shape 63a of the inner wall 63 of the stirring tank 23 is different from that of the first embodiment. Since the temperature control means 5, the stirring blade 3, and the driving means 8 have the same configuration as those of the first embodiment, the same parts are designated by the same reference numerals and detailed description thereof will be omitted.

In the present embodiment, the height difference between the concave portion 63b and the convex portion 63c in the concave-convex shape 63a of the inner wall 63 of the stirring tank 23 is formed so as to be equal to or less than the thickness of the stirring tank 23, as shown in FIG. The concave-convex shape 63a is a shape in which each of the concave portion 63b and the convex portion 63c in the concave-convex shape 63a includes a part of the spherical shape, that is, in the cross section of the stirring tank 23 as in the first embodiment. The contour on the wetted part side is formed in a mountain valley shape so as to be curved, and the uneven shape 63a is periodically formed in the four directions of the stirring shaft.

As described above, in the present embodiment, the height difference between the concave portion 63b and the convex portion 63c in the concave-convex shape 63a of the inner wall 63 of the stirring tank 23 is formed so as to be equal to or less than the thickness of the stirring tank 23. The strength (robustness) of the stirring tank 23 can be increased by increasing the thickness of the stirring tank 23 with respect to the uneven shape 63a, and as a result, the tank capacity can be increased and the agitated object having a high specific gravity can be reliably stirred. It can be carried out.

It should be noted that the present invention is not limited to the configuration of the above-described embodiment, but is indicated by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims. Will be done.

For example, in the first and third embodiments described above, a stirring device in which the concave and convex portions of the inner walls 61 and 63 of the stirring tanks 21 and 23 each include a part of the spherical shape. In 11, 13, and the second embodiment, the stirring device 12 in which the shape of the inner wall 62 of the stirring tank 22 includes a part of the conical surface shape has been described, but the recesses in the uneven shape of the inner wall of the stirring tank and the recesses A stirring device may be used in which each shape of the convex portion includes a part of at least one shape selected from the group consisting of an elliptical surface shape, a conical surface shape, and a polygonal pyramid surface shape. By forming the inner wall of the stirring tank in the above shape in this way, it is possible to effectively adjust the temperature of the object to be agitated and make the temperature and concentration uniform.

Further, in the above-described embodiment, the stirring devices 11 and 13 such that the concave-convex shapes 61a to 63a of the inner walls 61 to 63 include a part of the spherical shape, and stirring such that a part of the conical surface shape is included. Although the device 12 has been described, the concave-convex shape may be any shape that does not easily obstruct the flow of the object to be agitated during stirring, and the concave and convex portions may be one unit and the units may be arranged in parallel. Just do it. Further, each of the concave portion and the convex portion does not have to have a symmetrical shape.

Further, in the above-described embodiment, the stirring device in which the uneven shapes 61a to 63a are periodically formed in the four directions of the stirring shaft has been described, but the stirring device in which the uneven shapes are formed aperiodically and some of them. It may be a stirrer in which only agitators are formed periodically.

Further, in the above-described embodiment, the stirring devices 11 to 13 not provided with the baffle are shown, but the stirring device may be provided with the baffle as long as the effect of the present invention is not impaired.

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. Each part of the stirring device shown below is as shown in FIG. 7.

[Example 1]
In the stirring device of the first embodiment, the stirring tank has a substantially cylindrical shape with a tank diameter D = 200 mm, a plate thickness t = 1.5 mm, and a body height B = 250 mm (effective height 200 mm), and the tank of the stirring tank. The bottom portion A had a substantially half-rotated ellipsoidal shape, and the entire stirring tank was made of SUS316L steel. The uneven shape of the inner wall of the stirring tank has a height difference of 7a = 30 mm, a periodic length of 7b = 100 mm, a periodic mountain-valley shape in which concave portions and convex portions are continuous in a hemispherical shape, and a wetted portion in the cross section of the stirring tank. The contour on the side is curved, and 24 sets of recesses and protrusions are provided in a portion within an effective height of 200 mm of the inner wall of the stirring tank (see FIG. 1). Further, the inner wall was polished with a buff having a particle size equivalent to P400 specified in JIS R 6010 and then electropolished to finish Ra = 1.0 μm. The effective height means the height from the lower end of the body portion in the stirring tank that can accept the material to be stirred. The Ra is measured using a roughness measuring device (laser microscope manufactured by KEYENCE CORPORATION, model number: VK-X150 / 160).

The stirring shaft was φ10 mm. The stirring blade was a double blade having a blade diameter d = 120 mm, a blade height b = 80 mm, and a plate thickness of 1.5 mm, and the blade bottom shape was matched to the tank bottom shape. A jacket was used as the temperature control means, and the jacket width X = 10 mm and the jacket height Y = 50 mm. The driving means was a motor. The baffle was not installed.

[Example 2]
Similar to Example 1 except that the concave portion and the convex portion have a conical surface shape having the same bottom area and height, a continuous periodic mountain valley shape, and the contour on the wetted portion side in the cross section of the stirring tank is straight. (See FIG. 4).

[Comparison example]
The configuration was the same as that of Example 1 except that no uneven shape was formed on any part of the inner wall of the stirring tank (see FIG. 6).

<Evaluation>
The temperature rise time and temperature rise rate ratio were measured, and the results are shown in Table 1.

[Raising time and heating rate ratio]
In heating the agitated object using the jacket as a temperature control means, the time until the temperature of the agitated object became 25 ° C. to 60 ° C. was measured under the following conditions, and this measured value was taken as the temperature rising time. Further, the temperature rise rate ratio was calculated as a ratio (%) of the temperature rise rate of each example when the temperature rise rate of the comparative example was 100%.
Material to be agitated: 4 L of pure water, initial temperature 20 ° C
Heat medium: Mixture of water and ethylene glycol (ethylene glycol 75% by mass, residual water), inlet temperature 70 ° C., flow velocity 1.0 to 1.5 m / sec (0.5 to 0.75 L / sec), jacket Input from the bottom Rotation speed of stirring shaft: 80 rpm

The height of the liquid level of the object to be agitated in the stirring tank was almost the same in both Examples and Comparative Examples because the number of concave portions and convex portions in the concave-convex shape was the same.

11, 12, 13 Stirrer b Stirring object 21, 22, 23 Stirrer tank 3 Stirrer blade 4 Stirrer shaft 5 Temperature control means 61, 62, 63 Inner wall 61a, 62a, 63a Concavo-convex shape 8 Drive means

Claims (6)

A stirring device that stirs an object to be agitated while adjusting the temperature.
A stirring tank that houses the material to be agitated and
A temperature control means provided outside the stirring tank and adjusting the temperature of the object to be stirred via the stirring tank.
A stirring blade arranged in the stirring tank and stirring the object to be agitated while rotating,
It is connected to the stirring blade via a stirring shaft and includes a driving means for rotationally driving the stirring blade.
At least a part of the inner wall of the stirring tank is formed into a predetermined uneven shape.
Each shape of the recess and the convex portion of the concavo-convex shape, Ri conical surface shape der having the same bottom area and height,
A stirring device characterized in that each of the concave portion and the convex portion is periodically scattered in the stirring axis direction at least a part of the inner wall. The stirring device according to claim 1, wherein the surface area of the inner wall of the stirring tank is more than 1.1 times the surface area of the virtual inner wall when the inner wall is assumed to be flat. The stirring device according to claim 1 or 2, wherein the roughness of at least a part of the inner wall of the stirring tank is 1.0 μm or less in arithmetic average roughness (Ra). The stirring device according to any one of claims 1 to 3, wherein the height difference between the concave portion and the convex portion in the concave-convex shape is 10 mm or more and 40 mm or less, and the period of the concave-convex shape is 100 mm or more. In the projected image when the stirring tank is projected on the projection plane orthogonal to the stirring axis, the minimum value of the dimension between the inner walls crossing the stirring axis is 4 of the maximum value of the height difference between the concave portion and the convex portion in the concave-convex shape. The stirring device according to any one of claims 1 to 4, which is more than doubled. The stirring device according to any one of claims 1 to 5, wherein the stirring tank is made of a metal material containing stainless steel, copper or aluminum as a main component.

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