Stirring device

Abstract

This agitator comprises an agitation tank for accommodating a fluid to be treated that contains particles, a flow blade for stirring the fluid accommodated in the agitation tank, and a shear blade 16 that is provided further on an inner side than the flow blade at the bottom of the agitation tank and disperses the particles. The shear blade 16 includes a base 60 that rotates around a predetermined axis and a plurality of blades 62 each of which is disposed on an edge of the base 60. An angle formed by the blade 62 and a tangential line of the outer periphery of the base 60 on the downstream side in the rotation direction of the base 60 is larger than 0 degree and equal to or smaller than 60 degrees.

Description

Technical Field

[0001] The present invention relates to a stirring device.

Background Art

[0002] Conventionally, a stirring device for stirring a fluid to be treated is known. The stirring device has various functions depending on the properties of the fluid to be treated, such as its viscosity. For example, an emulsion used in hair care products and skin care products is obtained by refining an oil phase (e.g., silicone oil) and dispersing it in an aqueous phase. To form such an emulsion, there is an emulsification method in which a shearing force is applied to the oil phase to refine it. For such an emulsion, a stable state in which the dispersed particles do not separate is required over a long period of time. Also, in a low-viscosity emulsion, the dispersed particles are required to have a particle diameter of sub-micron or less. As a stirring device for such applications, for example, the one described in Patent Document 1 is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, in such a stirring device, it has been desired to further refine the particles in the fluid to be treated. To refine the particles in the fluid to be treated, it is conceivable to increase the rotational speed of the shearing blade. However, when the rotational speed of the shearing blade is increased, new problems arise, such as an increase in the energy consumption of the stirring device and a shortening of the life of consumables such as the seal structure.

[0005] An object of the present invention is to provide a stirring device that can refine the particles in the fluid to be treated while suppressing an increase in energy consumption and preventing the shortening of the life of consumables.

Means for Solving the Problems

[0006] According to one aspect of the present invention, an agitation device is provided comprising: an agitation tank for containing a fluid to be treated containing particles; a fluid blade for agitating the fluid to be treated contained in the agitation tank; and a shear blade positioned inward from the fluid blade at the bottom of the agitation tank for dispersing the particles, wherein the shear blade comprises a base that rotates around a predetermined axis and a plurality of blades provided on the edge of the base, and the angle between the tangent to the outer circumference of the base at the position where each of the plurality of blades is fixed to the base and the blade downstream of the base in the direction of rotation is greater than 0 degrees and less than or equal to 60 degrees.

[0007] Furthermore, according to one aspect of the present invention, an agitation device is provided comprising a stirring tank for containing a fluid to be treated that contains particles, and a shear blade for dispersing the particles contained in the fluid to be treated contained in the stirring tank, wherein the shear blade comprises a base that rotates around a predetermined axis and a plurality of blades provided on the edge of the base, and the angle that each of the plurality of blades makes between the tangent to the outer circumference of the base at the position where it is fixed to the base and the blade downstream of the base in the direction of rotation is greater than 0 degrees and 60 degrees or less. [Effects of the Invention]

[0008] This configuration allows for the miniaturization of particles in the fluid being processed while suppressing an increase in energy consumption and preventing a shortened lifespan of consumables. [Brief explanation of the drawing]

[0009] [Figure 1] This is a longitudinal cross-sectional view of a stirring device according to an embodiment. [Figure 2] This is a cross-sectional view of section AA in Figure 1. [Figure 3] This is a longitudinal cross-sectional view of the stirring device. [Figure 4] This is a top view of a shear wing. [Figure 5] This is a side view of the shear wing. [Figure 6] This is an enlarged view of region A in Figure 4. [Figure 7] This is a top view of a shear wing, modified for clarity. [Figure 8] This graph shows the experimental results from the first embodiment. [Figure 9] This graph shows the experimental results from the second example. [Modes for carrying out the invention]

[0010] The following describes a stirring device according to an embodiment of the present invention. In the embodiment, a stirring device used for emulsifying various materials such as cosmetics and food products will be given as an example and described in detail. The present invention is not limited to stirring devices for stirring emulsions, but can also be applied to stirring devices for dispersing cellulose nanofibers. Furthermore, although the following embodiment uses a stirring device equipped with multiple independently driven blades as an example, the present invention can also be applied to a stirring device having only shear blades.

[0011] Figure 1 is a longitudinal cross-sectional view of an agitator according to an embodiment, and Figure 2 is a cross-sectional view of section AA in Figure 1. As shown in Figures 1 and 2, the agitator 10 comprises an agitator 12 for containing the fluid to be processed, a flow blade 14, a shear blade 16, and a gate blade 18.

[0012] The flow blades 14, shear blades 16, and gate blades 18 are housed within the stirring tank 12 and are each rotated around a vertically extending drive shaft. The flow blades 14, shear blades 16, and gate blades 18 are driven separately by drive units such as motors located outside the stirring tank 12. Therefore, the flow blades 14, shear blades 16, and gate blades 18 can rotate independently of each other at different rotational speeds and in different directions. The rotational direction R3 and rotational speed of the flow blades 14, shear blades 16, and gate blades 18 are appropriately determined according to the properties of the fluid being processed and / or the capacity of the stirring tank 12.

[0013] The stirring tank 12 is a container with a circular side cross-sectional shape of its inner circumferential wall 12a. This stirring tank 12 has a cylindrical straight body section 20 at the top and a frustoconical constricted section 22 at the bottom. The straight body section 20 and the constricted section 22 are formed integrally. The inner diameter of the straight body section 20 is constant in the vertical direction. The inner diameter of the constricted section 22 decreases towards the bottom. In Figure 1, the upper end of the stirring tank 12 is open, but the upper end may be closed. A jacket section 24 is formed outside the stirring tank 12 as a heating / cooling section. A heat transfer medium or coolant flows through this jacket section 24, thereby heating or removing heat (cooling) the fluid to be processed inside the stirring tank 12.

[0014] The fluid blade 14 is mounted along the inner circumferential wall 12a of the stirring tank 12 and rotates around the drive shaft. The fluid blade 14 has a ribbon blade shape, and as the fluid blade 14 rotates, a guided flow is formed along the inner circumferential wall 12a of the stirring tank 12 toward the bottom. Once the guided flow is formed in the stirring tank 12, the fluid to be processed is mixed and then atomized by the shear blade 16 located at the bottom.

[0015] As shown in Figures 1 and 2, the fluid blade 14 is arranged along the inner circumferential wall 12a of the stirring tank 12 and comprises a plurality of fluid blade bodies 26 having a predetermined width, a plurality of support rods 28 that support these fluid blade bodies 26 at an in-diameter position, and a support ring 30 that connects and supports the fluid blade bodies 26 from below. In the illustrated example, there are two fluid blade bodies 26. The fluid blade bodies 26, support rods 28, and support ring 30 are integrally formed by welding or the like. Each support rod 28 is a straight rod extending in the vertical direction and is fixed to the fluid blade body 26 at the top and bottom. Each support rod 28 is connected to a fluid blade drive unit (not shown) provided above the stirring tank 12 via a fluid blade drive shaft 34. The support ring 30 fixes the lower ends of each fluid blade body 26 together.

[0016] Each flow wing body 26 is formed in a curved strip shape. The flow wing body 26 includes two upper wings 36 disposed within the straight barrel portion 20 and two lower wings 38 disposed within the throttle portion 22. The two upper wings 36 each extend, for example, so as to rotate 180 degrees around the drive shaft in a top view. The two upper wings 36 are arranged at 180-degree intervals in a top view. The two lower wings 38 extend, for example, so as to rotate 90 degrees around the drive shaft in a top view. The upper wing 36 is disposed at a certain distance from the inner peripheral wall 12a of the stirring tank 12 and extends from the top to the bottom while swirling while inclining at a certain angle in the circumferential direction. When the upper wing 36 is rotated, the fluid to be treated within the straight barrel portion 20 is stirred and flows toward the bottom.

[0017] The diameter of the lower wing 38 corresponds to the inner shape of the throttle portion 22. Specifically, the diameter of the lower wing 38 is slightly smaller than the inner peripheral wall of the straight barrel portion 20 at the top and slightly larger than the outer diameter of the drive shaft of the shear wing 16 at the bottom. The lower wing 38 has a shape that is curved so as to bulge in the direction opposite to the rotation direction R3 in a top view (see particularly FIG. 2).

[0018] The upper wing 36 and the lower wing 38 are connected at the joint portion 40 and are continuous with each other. Specifically, as shown in FIG. 2, the upper wing 36 and the lower wing 38 are connected at the joint portion 40 by welding or the like in a state where the surface of the strip-shaped body constituting the lower wing 38 abuts against the radially inner edge of the strip-shaped body constituting the upper wing 36. Thereby, the upper wing 36 and the lower wing 38 are integrated.

[0019] The lower wing 38 directs the swirling and downward flow of the fluid to be treated formed by the upper wing 36 toward the center of the stirring tank 12. Thereby, the fluid to be treated is guided in the direction of the shear wing 16.

[0020] FIG. 3 is a longitudinal sectional view of the stirring device. More specifically, FIG. 3 is a longitudinal sectional view in which the shear wing and its periphery are enlarged. The shear wing 16 applies a shearing force to the fluid to be treated by rotation. As the shear wing 16, a dispersing wing is used. The configuration of the shear wing 16 will be described later.

[0021] A drive shaft 46 for the shear blades, which extends downward, is connected to the shear blades 16. Although not shown in the illustration, a seal is provided between the agitation tank 12 and the drive shaft 46 for the shear blades to prevent leakage of the material being agitated. The drive shaft 46 for the shear blades is connected to a drive unit for the shear blades (not shown) located below the agitation tank 12. This allows the shear blades 16 to be rotated around a vertical axis that extends in the vertical direction.

[0022] Returning to Figure 1, the gate blade 18 comprises a gate blade body 48 formed in the shape of a rectangular frame symmetrical with respect to the rotation center (vertical axis) as shown in the figure, and a gate blade drive shaft 52 located above the gate blade body 48 and connected to the gate blade drive unit. The gate blade body 48 is formed by integrally combining an upper horizontal member 48U, a left member 48L, a right member 48R, and a lower horizontal member 48D, each formed in the shape of a rod, and has a frame structure made of elongated rod-shaped members. The gate blade 18 rotates in the opposite direction to the flow blade 14, or rotates in the same direction as the flow blade 14 at a different rotational speed. The gate blade drive unit (not shown) for rotating the gate blade 18 is located above the stirring tank 12. The gate blade drive shaft 52 is arranged concentrically with the flow blade drive shaft 34. The gate blade drive unit can also function as the flow blade drive unit. In this case, the fluid blade 14 and the gate blade 18 are configured to receive driving forces at different rotational speeds (or in different rotational directions) via a reduction gear or the like. The rotational speeds of the fluid blade 14 and the gate blade 18 are set to be sufficiently slower than those of the shear blade 16. Alternatively, while the fluid blade 14 and the shear blade 16 are rotating, the gate blade 18 may remain stationary without rotating at all.

[0023] The combination of the flow blade 14 and the gate blade 18 creates a speed difference between the movement of the agitated material due to the rotation of the gate blade 18 and the movement of the agitated material due to the rotation of the flow blade 14 within the agitated tank 12. This suppresses "co-rotation," where the agitated material moves in conjunction with the flow blade 14 within the agitated tank 12, and allows the agitated material to flow smoothly throughout the agitated tank 12.

[0024] Figure 4 is a top view of the shear blade, and Figure 5 is a side view of the shear blade. Figure 6 is an enlarged view of area A in Figure 4. As shown in Figures 4 to 6, the shear blade 16 rotates along the drive shaft 46 for the shear blade in a direction perpendicular to the flow of the fluid to be processed toward the shear blade 16, thereby applying a shear force to the fluid to be processed. The shear blade 16 is positioned inside the flow blade 14 at the bottom of the stirring tank 12. In Figure 4, the base 60 is assumed to rotate counterclockwise (indicated by arrow R4) in a top view. The shear blade 16 comprises a base 60 and a plurality of blades 62. The base 60 is made up of a flat, disc-shaped plate and is fixed to the upper end surface of the drive shaft 46 for the shear blade. The base 60 is fixed to the drive shaft 46 for the shear blade such that its center, when viewed from above, coincides with the axis of rotation of the drive shaft 46 for the shear blade. Therefore, the base 60 rotates together with the drive shaft 46 for the shear blades, coaxially with the drive shaft 46 for the shear blades.

[0025] Multiple blades 62 are fixed to the base 60 along its edge. The multiple blades 62 revolve around the vertical axis as the base 60 rotates, thereby colliding with the fluid to be processed and applying a shearing force to the fluid. Each of the multiple blades 62 is formed from a rectangular flat plate. The vertically extending side of the blade 62 is parallel to the drive shaft 46 for the shearing blades. The horizontally extending side of the blade 62 is parallel to the main surface of the base 60. The blades 62 are fixed to the edge of the base 60, for example, by welding. The multiple blades 62 are arranged at equal angular intervals with respect to the center of the base 60. The blades 62 may be fixed to the base 60 near their vertical center. In that case, in a side view, the blades 62 extend upward from the upper main surface of the base 60 and downward from the bottom main surface of the base 60. When viewed from above, the tip of the blade 62 (the radially outer end of the base 60) is oriented downstream in the rotational direction of the base 60. Multiple blades 62 have a predetermined angle α with the tangent L of the outer circumference of the base 60. The tangent L is the tangent at the position where the blade 62 is fixed to the base 60. The angle α is the acute angle formed between the tangent of the outer circumference of the base 60 when viewed from above and the main surface 62a of the blade 62 (the main surface facing downstream in the rotational direction and colliding with the fluid being processed). The angle α is preferably greater than 0 and 60 degrees or less, more preferably 15 degrees or more and 45 degrees or less, and even more preferably 20 degrees or more and 40 degrees or less. Experiments by the inventors have shown that by setting the angle α within the above range, the shear force applied to the fluid being processed can be increased, and the particles contained in the fluid being processed can be made finer.

[0026] In this embodiment, the blade 62 is a flat plate with a flat main surface 62a. However, a blade 62 with a curved main surface 62a may also be used. In this case, angle α refers to the angle between the tangent to the main surface 62a at the point where the base 60 and the blade 62 are fixed, and the tangent to the outer circumference of the base 60.

[0027] Next, the operation of the agitator 10 will be described. Referring to Figures 1 to 3, when the fluid to be processed is injected into the agitator 12 and the gate blade drive unit, flow blade drive unit, and shear blade drive unit are turned ON, the flow blade 14, shear blade 16, and gate blade 18 are each driven to rotate in predetermined directions. As a result, the flow blade body 26 pushes the fluid to be processed in the straight body 20 toward the bottom, creating an induced flow F in the agitator 12 that flows toward the bottom along the inner circumferential wall 12a. The induced flow F continuously supplies the fluid to be processed to the shear blade 16.

[0028] The flow of the fluid to be processed supplied to the shear blade 16 flows towards the top along the drive shaft 46 for the shear blade. Near the shear blade 16, a shear force acts on the fluid to be processed due to the rotation of the shear blade 16, and the particles contained in the fluid to be processed are refined within the fluid. Subsequently, the fluid to be processed flows upward toward the straight body section 20. The fluid to be processed is stirred within the straight body section 20 by the upper blade 36 and then supplied to the shear blade 16, repeating this cycle.

[0029] The phenomena near the shear blades 16 will be explained in more detail. Referring to Figures 4 to 6, when the fluid to be processed reaches the vicinity of the shear blades 16, the fluid comes into contact with the shear blades 16. When the fluid to be processed comes into contact with the main surface 62a of the blades 62, a shear force acts on the fluid, and the particles in the fluid are refined. Furthermore, by setting the angle α within the range described above, the shear force can be increased, and the particles in the fluid to be processed can be refined even further. As a result, even if the rotation speed of the shear blades 16 is set low, a refinement effect equivalent to or better than that of a stirrer where the blade angle is not adjusted and the shear blades are set to high speed can be expected. Maintaining a low rotation speed of the shear blades 16 extends the life of consumables, including the seal between the stirring tank 12 and the drive shaft 46 for the shear blades. In addition, heat generation caused by the rotation of the drive shaft 46 for the shear blades is suppressed, and the temperature inside the tank can be controlled well.

[0030] Next, a modified example of the embodiment will be described.

[0031] Figure 7 is a top view of the shear blade of a modified stirring device. As shown in Figure 7, the base 160 of the shear blade 116 has a cross shape in top view. The base 160 has four protrusions 164 that project radially outward. Each of the multiple blades 162 is fixed to the tip of a protrusion 164. Compared to the base 60 described above, this base 160 can be said to have a notch in which the edge of the base 160 is recessed toward the center. The notch acts as a flow path 166 through which the fluid to be processed flows from the bottom to the top of the base 60. The flow path 166 is formed between adjacent protrusions 164.

[0032] Next, the operation of the modified configuration will be explained. As described above, when the agitator is driven, a flow is generated near the shear blades 116 from the bottom to the top. By providing a flow path 166 in the base 160, when the shear blades 116 are rotated, the fluid to be processed flows through the flow path 166 from the bottom to the top of the shear blades 116. As the shear blades 116 rotate, the side surface of the base 160 that defines the flow path 166 comes into contact with the fluid to be processed in the flow path 166, thereby increasing the shear force applied to the fluid to be processed. The shape and number of flow paths 166 are not limited to those shown in the illustration; various shapes and numbers can be used as long as the fluid to be processed can flow from the bottom to the top of the base 160. The side surface of the shear blades 116 that define the flow path 166 may also be inclined.

[0033] Through holes formed in the base 160 may be used as flow channels. The position and number of through holes are not particularly limited.

[0034] The following describes embodiments of the present invention. Figure 8 is a graph showing the experimental results according to the first embodiment. In the experiment, a shear blade was rotated at a constant rotational speed in a stirring tank of a constant capacity, and the change in particle size ratio was observed when the angle α was changed. In the graph of Figure 8, the horizontal axis represents the angle α, and the vertical axis represents the particle size ratio. The particle size ratio is defined as 100% for the particle size when the angle α is 0 degrees. As can be seen from Figure 8, when the angle α is greater than 0 degrees and 60 degrees or less, the particle size ratio is 100% or less. It can also be seen that when the angle α is between 15 degrees and 45 degrees, the particle size ratio is approximately 85% or less. Furthermore, it can be seen that when the angle α is between 20 degrees and 40 degrees, the particle size ratio is approximately 78% or less. In this way, the particle size ratio can be reduced by setting the angle α within a predetermined range.

[0035] Figure 9 is a graph showing the experimental results from the second embodiment. In the experiment, the same experiment as in the first embodiment was performed for both a shear blade with a flow channel (shear blade shown in Figure 7) and a shear blade without a flow channel, and the change in particle size ratio was observed. In the graph in Figure 9, the horizontal axis represents the angle α, and the vertical axis represents the particle size ratio. The particle size ratio is defined as 100% for the particle size when the angle α is 0 degrees. In Figure 9, the dashed line shows the change in particle size ratio when using a shear blade without a flow channel, and the solid line shows the change in particle size ratio when using a shear blade with a flow channel. It can be seen that when the angle α is the same, the particle size ratio is smaller when using a shear blade with a flow channel.

[0036] The present invention is not limited to the embodiments described above, and the configuration of the embodiments can be modified as appropriate without departing from the spirit of the invention. [Industrial applicability]

[0037] This invention relates to a stirring device. [Explanation of Symbols]

[0038] 10 Agitator, 12 Agitator, 14 Fluid impeller, 16 Shear impeller, 18 Gate impeller, 60 Base, 62 Blade, 62a Main surface, 116 Shear impeller, 160 Base, 162 Blade, 166 Flow channel.

Claims

1. A stirring tank containing the fluid to be treated which contains particles, A fluid blade for stirring the fluid to be processed contained in the stirring tank, The stirring tank comprises a shear blade positioned inside the flow blade at the bottom of the tank for dispersing the particles, The aforementioned shear blade is A base that rotates around a predetermined axis, It comprises a plurality of blades provided on the edge of the base, The angle between the tangent to the outer circumference of the base and the blade at the position where each of the plurality of blades is fixed to the base, on the downstream side of the base in the rotational direction, is 15 degrees or more and 60 degrees or less. Each of the blades is a flat plate having a main surface facing the downstream side in the rotational direction of the base, fixed to the base near its center in the vertical direction, extending upward from the upper main surface of the base, and extending downward from the bottom main surface of the base. A stirring device wherein the fluid to be processed, containing the particles refined by the shear blades, flows upward toward the top of the stirring tank.

2. The stirring device according to claim 1, wherein the stirring device drives the shear blades at a low rotation speed.

3. It is equipped with a drive shaft for the shear blades that is connected to the shear blades and extends downward, Each of the blades is formed from a rectangular plate, with the vertically extending side parallel to the drive shaft for the shear blade and the horizontally extending side parallel to the main surface of the base. The stirring device according to claim 1 or 2.

4. The stirring device according to claim 1 or 2, wherein the angle between the tangent to the outer circumference of the base and the blade on the downstream side of the base in the rotational direction is 45 degrees or less.

5. The stirring device according to claim 1 or 2, wherein the base portion has a disc shape and is arranged in the stirring tank such that the center of the disc coincides with the predetermined axis.

6. The stirring device according to claim 1 or 2, wherein the base portion is provided with a flow path for the fluid to be processed to flow from the bottom to the top of the stirring tank.

7. A stirring tank containing the fluid to be treated which contains particles, The tank comprises a stirring tank and a shear blade for dispersing the particles contained in the fluid to be treated, The aforementioned shear blade is A base that rotates around a predetermined axis, It comprises a plurality of blades provided on the edge of the base, The angle between the tangent to the outer circumference of the base and the blade at the position where each of the plurality of blades is fixed to the base, on the downstream side of the base in the rotational direction, is 15 degrees or more and 60 degrees or less. Each of the blades is a flat plate having a main surface facing the downstream side in the rotational direction of the base, fixed to the base near its center in the vertical direction, extending upward from the upper main surface of the base, and extending downward from the bottom main surface of the base. A stirring device in which the fluid to be processed, containing the particles refined by the shear blades, flows upward.

Images