JP7148279B2 - Stirring method and stirring device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a stirring method and a stirring device.

Radial flow type impellers such as disk turbine impellers and flat paddle impellers are characterized by high shear stress and in that the discharge flow from the impellers is directed in the radial direction of the mixing tank. On the other hand, it is difficult to form a flow in the axial direction of the agitation vessel, and the flow in the vessel is likely to be divided vertically, so there is a problem that uniform mixing in the entire vessel is low.

Various techniques have been developed to improve uniform mixing in the tank. For example, in the techniques disclosed in Patent Documents 1 and 2, a vertical circulation flow can be formed by combining a radial flow type stirring blade and an axial flow type stirring blade. Further, in the technique disclosed in Patent Document 3, it is possible to form a vertical circulation flow by designing the blade area of the stirring impeller to increase toward the bottom of the tank.

Japanese Patent No. 5921433 JP 2015-054272 A JP-A-2006-87998

However, in the techniques of Patent Literatures 1 and 2, although the axial flow type stirring blades form a vertical circulation flow in the entire tank due to a large discharge flow in the axial direction, the resulting shear force is small. Therefore, although uniform mixing can be improved by using axial flow type stirring blades, there is a problem that the shear stress that should be obtained by radial flow type stirring blades is reduced. In addition, the technique of Patent Document 3 has a problem that the blade area is large, so that a very large amount of power is consumed, and the obtained shear stress becomes excessively large.

Generally, when three-stage impellers are used, the lower impeller is placed as close to the tank bottom as possible, and the upper impeller is placed at a certain distance from the liquid surface so as not to disturb the liquid surface. Further, the intermediate blades are arranged in the middle between the upper blades and the lower blades so that the distance between the stirring blades is uniform. In the case of this normal arrangement, until now it was thought that the radial discharge flow generated by each stirring blade flowed independently. As shown in 7(b), it was found that the discharge flow generated by the lower impeller directed downward toward the bottom of the tank, and the discharge flow generated by the upper two stirring impellers joined together. In addition, the discharge flow generated by the two stages of stirring blades is well mixed because it joins before it collides with the wall or baffle plate of the stirring vessel and splits vertically. However, since the circulating flow due to the discharge flow generated by the lower stage stirring blades is generated separately from the discharge flow generated by the upper two stage stirring blades, it is difficult for the upper liquid composition to migrate to the bottom of the tank. Therefore, when the inside of the tank is stirred with the usual arrangement of the stirring blades as described above, the uniformity of mixing in the entire tank becomes low.
Radial flow type agitating impellers can obtain a large shearing force, and are often used in processes that require shearing force such as gas-liquid reaction, emulsification, and solid-liquid dispersion. Homogeneous mixing is also important from the point of view of product quality. However, if the inside of the tank is stirred with the usual arrangement of stirring blades as described above and the uniformity of mixing in the entire tank is low, problems such as deterioration of product quality are likely to occur.
Here, if the number of rotations is increased in order to improve uniformity of mixing, the resulting shear force also increases. However, in the gas-liquid reaction process, when the shear force increases, the mass transfer coefficient of the gas increases, shortening the reaction time and possibly reducing the yield and quality of the product. Also, in the emulsification and solid-liquid dispersion processes, as the shear force increases, the droplet diameter (particle diameter) decreases, so desired physical properties may not be obtained and the quality of the product may deteriorate. Therefore, there is a demand for a stirring method that imparts a shearing force that meets product specifications and at the same time achieves high uniform mixing.

An object of the present invention is to provide a stirring method and a stirring device that can solve the problems of the prior art described above.

The present invention uses a stirring device comprising a cylindrical stirring vessel, a rotating shaft arranged along the central axis of the stirring vessel, and a plurality of stirring blades attached to the rotating shaft, A stirring method for stirring a liquid material to be stirred contained in a tank, wherein the stirring blades are all radial flow type stirring blades, and are arranged in three stages spaced apart in the axial direction of the rotating shaft. The distance h2 between the stirring blades located in the lower stage and the stirring blades located in the middle stage, and the distance h3 between the stirring vanes located in the upper stage and the stirring vanes located in the middle stage. The ratio (h2/h3) is 0.50 or more and 0.95 or less, and the distance h1 between the lower stirring blade and the bottom of the stirring vessel, and the distance from the bottom of the stirring vessel to the A stirring method in which the material to be stirred is stirred by rotating the rotating shaft under the condition that the ratio (h1/H) to the height H to the upper end of the material to be stirred is 0.20 or more and 0.30 or less. It provides

The present invention also provides a stirring device comprising a cylindrical stirring vessel, a rotating shaft arranged along the central axis of the stirring vessel, and a plurality of stirring blades attached to the rotating shaft, A baffle plate is attached to the inner peripheral surface of the stirring vessel, and the stirring blades are all radial flow type stirring blades, and are mounted in three stages at intervals in the axial direction of the rotating shaft, Ratio (h2 /h3) is 0.50 or more and 0.95 or less, and the ratio (h1/ D) is 0.190 or more and 0.345 or less.

According to the stirring method and stirring device of the present invention, it is possible to improve uniform mixing while maintaining the shearing force of the radial flow stirring blades.

FIG. 1 is a schematic cross-sectional view of a stirring device according to one embodiment of the stirring method and stirring device of the present invention. FIG. 2 is a cross-sectional view perpendicular to the rotation axis of the stirring device shown in FIG. 1, and is a common cross-sectional view taken along lines Ia-Ia, Ib-Ib and Ic-Ic in FIG. 3 is a perspective view of a stirring blade of the stirring device shown in FIG. 1. FIG. FIG. 4(a) is a side view of the stirring blade shown in FIG. 3, and FIG. 4(b) is a diagram for explaining the inclination angle of the blades of the stirring blade. FIG. 5 is a diagram illustrating the flow pattern generated in the agitation tank when using the agitation method according to one embodiment of the present invention. 6(a), 6(b), and 6(c) are diagrams illustrating the shape of baffle plates of a stirring device according to another embodiment of the present invention. 7(a), 7(b), 7(c) and 7(d) are diagrams for explaining the flow patterns generated in the stirring tank when the stirring methods of the examples and comparative examples are used. be. FIG. 8(a) is a diagram showing the trajectory in the agitation tank when agitation is performed by the agitation method of Example 1, and FIG. is a diagram showing the trajectory of . FIG. 9 is a diagram showing changes over time in the separation strength when stirring is performed by the stirring methods of Example 1 and Comparative Example 1. FIG. FIG. 10 is a graph showing torque 5-section moving averages when stirring by the stirring methods of Example 1 and Comparative Example 1. FIG. FIG. 11 is a diagram showing torque 5-section moving averages when stirring by the stirring methods of Example 1 and Comparative Example 11. FIG.

The present invention will be described below based on its preferred embodiments.
First, a stirring device used in a preferred embodiment of the stirring method of the present invention will be described. As shown in FIGS. 1 and 2, the stirring device 1 used in one embodiment of the stirring method of the present invention includes a cylindrical stirring vessel 10 and a rotating shaft 11 arranged along the central axis of the stirring vessel 10. , a plurality of stirring blades 20 attached to the rotating shaft 11 , and baffle plates 30 attached to the inner peripheral surface of the stirring vessel 10 .

As shown in FIGS. 1 and 2, the stirring vessel 10 is cylindrical and has a vessel bottom 10a. The shape of the tank bottom 10a can be the shape of the tank bottom of a general stirring tank 10, and is not particularly limited. The shape of the tank bottom 10a is preferably a 10% dish shape from the viewpoint of extracting the material to be treated and preventing the discharge flow from staying at the tank bottom.

The rotating shaft 11 is mounted so that its central axis is positioned at the same position as the central axis of the stirring vessel 10, as shown in FIGS. The rotating shaft 11 is connected at its upper end to a driving device (not shown) positioned above the stirring vessel 10 and is rotatable.

The stirring blade 20 is a radial flow type stirring blade. The term "radial flow type stirring blade" refers to a stirring blade that generates a flow that flows substantially perpendicularly to the rotating shaft in a direction away from the rotating shaft when the rotating shaft to which the stirring blade is attached is rotated. is. In other words, the radial-flow type stirring impeller produces a discharge flow in the radial direction of the stirring vessel. Examples of radial flow type stirring blades include disk turbine blades, paddle blades, disper blades, and the like. It is preferable to use disk turbine blades from the viewpoint of being able to

As shown in FIG. 1, the stirring blades 20 are attached to the rotating shaft 11 in three stages with intervals in the axial direction Z thereof. That is, the stirring device 1 has, as the stirring blades 20, an upper stirring blade 20u, a middle stirring blade 20m, and a lower stirring blade 20d. The upper stage stirring blade 20u, the middle stage stirring blade 20m, and the lower stage stirring blade 20d have the same configuration except that they are attached to the rotary shaft 11 at different positions. The three-stage stirring blades 20u, 20m, and 20d are attached to the rotating shaft 11 so that the distances between the stirring blades 20u, 20m, and 20d in the axial direction Z of the rotating shaft 11 are uneven.

In the stirring device 1, as shown in FIG. 1, the distance h2 between the lower stirring blade 20d and the middle stirring blade 20m is the same as the upper stirring blade 20u and the middle stirring blade 20m. is smaller than the distance h3 between
The distance h2 and the distance h3 are the distances between the midpoints M of the stirring blades 20 adjacent to each other in the axial direction Z of the rotating shaft 11 . The position of the midpoint M of each stirring blade 20 is the position that halves the distance between the upper end and the lower end of the blade 22 in the axial direction Z of the stirring blade 20, and therefore the distance h2 is positioned at the lower stage. The distance h3 is the distance between the middle point Md of the stirring blade 20d and the middle point Mm of the stirring blade 20m located in the middle stage. is the distance between the midpoint Mm of . A distance h1 and a distance h4, which will be described later, are also the distance between the middle point Md of the stirring blade 20d and the tank bottom 10a, and the distance between the middle point Mu of the stirring blade 20u and the upper end 50a of the object 50 to be stirred. In addition, when the one-stage stirring blade 20 has a plurality of blades 22 and the positions of the midpoints M of the blades 22 in the axial direction Z are different, the average position of the respective midpoints M in the axial direction Z is is the position of the midpoint M in the axial direction Z of .

The ratio of the distance h2 between the lower stirring blade 20d and the middle stirring blade 20m to the distance h3 between the upper stirring blade 20u and the middle stirring blade 20m (h2/ In h3), the discharge flow generated by the stirring blade 20u located in the upper stage is isolated, and the discharge flow generated by the stirring blades 20m and 20d located in the middle and lower stages merge and head toward the bottom of the tank, dividing the tank into two. , From the viewpoint of preventing the miscibility from deteriorating, it is preferably 0.50 or more, more preferably 0.70 or more, and still more preferably 0.76 or more. The discharge flow generated by the agitating blade 20d is directed toward the bottom of the vessel, and the discharge flows generated by the agitating blades 20u and 20m located in the upper and middle stages join together to divide the interior of the vessel into two, resulting in poor mixing. From the viewpoint of preventing this, it is preferably 0.95 or less, more preferably 0.90 or less, and even more preferably 0.87 or less. Specifically, the ratio (h2/h3) between the distance h2 and the distance h3 is preferably 0.50 or more and 0.95 or less, more preferably 0.70 or more and 0.90 or less, and 0 0.76 or more and 0.87 or less is more preferable.

In addition, the stirring blade 20d located in the lower stage has a certain distance h1 from the vessel bottom 10a of the stirring vessel 10. As shown in FIG. The distance h1 between the lower stirring blade 20d and the bottom 10a of the stirring vessel 10 is the distance between the middle point Md of the lower stirring blade 20d and the lower end of the inner surface of the vessel bottom 10a of the stirring vessel 10. means When the tank bottom 10a is provided with a drain port, a manhole, a gas supply pipe 42, etc., the imaginary lower end when assuming the shape of the inner surface of the tank bottom 10a that does not have them is the lower end of the inner surface of the tank bottom 10a. and

The ratio (h1/D) between the distance h1 between the lower stirring blade 20d and the bottom 10a of the stirring vessel 10 and the inner diameter D of the stirring vessel 10 is the discharge flow generated by the lower stirring blade 20d. toward the tank bottom 10a, and only the discharge flows generated by the upper and middle stirring blades 20u and 20m are merged, or only the discharge flows generated by the middle and lower stirring blades 20m and 20d are merged. From the viewpoint of preventing the inside of the stirring vessel 10 from being divided into two and the mixing performance being lowered, it is preferably 0.190 or more, more preferably 0.200 or more, and 0.210 or more It is more preferable that even if the discharge flows generated by the three-stage stirring blades 20u, 20m, and 20d are merged, the merged flow does not reach the lower part of the stirring tank 10, and the mixing performance is deteriorated. From the viewpoint of prevention, it is preferably 0.345 or less, more preferably 0.322 or less, and even more preferably 0.300 or less. Specifically, the ratio (h1/D) between the distance h1 and the inner diameter D is preferably 0.190 or more and 0.345 or less, more preferably 0.200 or more and 0.322 or less, and 0 It is more preferably 0.210 or more and 0.300 or less.

In this embodiment, the stirring blade 20 is a disk turbine blade comprising a disk 21 and blades 22 attached to the disk 21, as shown in FIG. The stirring blade 20 has six identical blades 22 . The blade 22 has a plate-like shape and has a pair of stirring surfaces 23 parallel to each other. The stirring surface 23 intersects with the rotating direction of the stirring blade 20 . The blades 22 of the stirring blades 20 are arranged such that the stirring surfaces 23 of the blades 22 are aligned with the axis of the rotating shaft 11 from the viewpoint of generating a discharge flow in the radial direction of the stirring tank when the rotating shaft 11 to which the stirring blades 20 are attached is rotated. Although it is preferable to be provided so as to be substantially parallel to the virtual line L parallel to the direction Z (see FIGS. 3 and 4A), the stirring surface 23 of the blade 22 is parallel to the virtual line L It may be slanted. Specifically, the angle θ between the stirring surface 23 of the impeller 22 and the imaginary line L produces a discharge flow in the radial direction of the stirring vessel 10 when the rotary shaft 11 to which the stirring blade 20 is attached is rotated. From the viewpoint, it is preferably 0° or more and 30° or less, and more preferably 0° or more and 20° or less (see FIG. 4B).

The number of blades 22 included in the stirring blade 20 is not particularly limited, but is preferably 2 or more and 10 or less, more preferably 4 or more and 8 or less, and still more preferably 5 or more and 7. less than one. The arrangement of the blades 22 in the stirring blade 20 is not particularly limited, but it is preferable that a plurality of blades are formed at equal intervals in the circumferential direction, and are arranged symmetrically about the rotating shaft 11. preferably.

The ratio (d/D) between the outer diameter d of the stirring blade and the inner diameter D of the stirring vessel is not particularly limited, but if d/D is too large, the distance from the peripheral edge of the stirring blade to the wall surface becomes small. As a result, the discharge flows from the three stages of stirring impellers reach the wall surface before they are all merged. On the other hand, if d/D is too small, the distance from the peripheral end of the stirring blade to the wall surface becomes large, and uniform mixing in the radial direction cannot be maintained. Therefore, the ratio (d/D) between the outer diameter d of the stirring blade and the inner diameter D of the stirring vessel is 0.25 or more and 0.50 or less, which is a general design value, preferably 0.30 or more and 0.40 or less. , and more preferably 0.32 or more and 0.35 or less (see FIGS. 1 and 2). The outer diameter d of the stirring blade 20 means the diameter of an imaginary circle R passing through the radial outer end of each blade 22 of the stirring blade 20 (see FIG. 2).

The length c of the blade 22 in the radial direction of the stirring surface 23 is not particularly limited, but if the length c is too small, the discharge flow becomes small. The ratio (c/d) to the diameter d is preferably 0.10 or more and 0.50 or less, more preferably 0.20 or more and 0.50 or less (see FIGS. 1 and 2).

The height b of the stirring blade 20 is not particularly limited, but if the height b is too small, the discharge flow becomes small. It is preferably 0.15 or more and 0.25 or less, and more preferably 0.18 or more and 0.23, which is a typical design value (see FIGS. 1 and 4). The height b of the stirring blade 20 means the height from the upper end to the lower end of the blade 22 of the stirring blade 20 in the axial direction Z (see FIGS. 1 and 4). When the blades 22 are provided so that the stirring surfaces 23 of the blades 22 are parallel to the imaginary line L parallel to the axial direction Z of the rotating shaft 11, the height b of the stirring blades 20 is equal to the height b of the stirring surfaces 23. It matches the length e in the direction orthogonal to the radial direction (see FIG. 4(a)). When the stirring surface 23 of the blade 22 is inclined with respect to the virtual line L, the height b of the stirring blade 20 is equal to the length e multiplied by cos θ (see FIG. 4(b)).

The ratio (c/b) between the length c of the stirring surface 23 of the impeller 22 in the radial direction and the height b of the stirring blade 20 is 0.4 or more and 3.4 or less, which is a general design value. It is preferably 1.0 or more and 2.5 or less (see FIG. 1).

The projected areas of the stirring surfaces 23 of the blades 22 of the stirring blades 20 onto the surfaces parallel to the axial direction Z of the stirring vessel 10 do not need to be the same. faster and may change the flow pattern. Also, the larger the projected area, the larger the power required for stirring. Therefore, among the blades 22u, 22m, and 22d of the three-stage stirring blades 20u, 20m, and 20d, respectively, when the projected area of the largest projected area is A1 and the projected area of the smallest projected area is A2, A1 and A2 (A1/A2) is preferably 1.0 or more and 1.1 or less. The projected area of the stirring surface 23 of the impeller 22 on the plane parallel to the axial direction Z of the stirring tank 10 is calculated as follows.

<Method for calculating the projected area of the stirring surface of the impeller on the plane parallel to the axial direction of the stirring tank>
A projected area A of the stirring surface 23 of the blade 22 of the stirring blade 20 onto a plane parallel to the axial direction Z of the stirring vessel 10 can be obtained by the following equation 1.
Projected area A = height of stirring blade b x length of stirring surface of blade in radial direction c (Equation 1)

The stirring tank 10 is provided with baffle plates 30 as shown in FIG. The shape of the baffle plate 30 is not particularly limited, but a general plate-like baffle plate is more preferable. The ratio (s1/D) between the width s1 of the baffle plate 30 and the inner diameter D of the stirring tank 10 shown in FIG. The following are preferable. Moreover, a gap may be provided between the baffle plate 30 and the inner peripheral surface of the agitating tank 10, and the width s2 of the gap between the baffle plate 30 and the inner peripheral surface of the agitating tank 10 and the width of the baffle plate 30 The ratio (s2/s1) to s1 is preferably 0 or more and 0.50 or less.

In addition, the ratio (s3/D) between the inner diameter D of the stirring vessel 10 and the distance s3 from the inner peripheral surface of the stirring vessel 10 to the radially inner end of the baffle plate 30 is 0.05 or more, which is a general design value. 0.25 or less is preferred.

The number of baffle plates 30 is not particularly limited, but is, for example, 1 or more and 10 or less, preferably 2 or more and 8 or less.

As shown in FIG. 1, a gas supply pipe 42 for gas supply, a pipe 41 for liquid supply, and the like are installed in the stirring tank 10 . The gas supply pipe 42 is installed in the lower part of the stirring tank 10 and the pipe 41 is installed in the upper part of the stirring tank 10 .

Although the volume V of the stirring vessel 10 is not particularly limited, when the volume V is small, the time required for the object 50 to be stirred to change from a non-uniform state to a uniform state is short, and thus the effect of the present invention can be obtained. may appear. Therefore, the volume V of the stirring tank 10 is preferably 30 L, more preferably 50 L or more, preferably 50000 L or less, more preferably 30000 L or less, more preferably 30 L or more and 50000 L or less, more preferably 50 L or more and 30000 L or less. It is below.

Next, a stirring method using the stirring device 1 described above will be described.
First, the material to be stirred 50 is placed in the stirring vessel 10 of the stirring device 1 having the above-described configuration. At this time, the object to be stirred 50 is accommodated in the stirring tank 10 so that the upper end 50a of the object to be stirred 50 is positioned at a fixed position. Specifically, it is preferable to maintain a constant positional relationship in the axial direction Z between the upper end 50a of the material to be stirred 50 and the stirring blades 20d and 20u located on the lower or upper stage. The position of the upper end 50a of the object to be stirred 50 may be controlled while a person visually confirms the position of the upper end 50a. ) may be provided and controlled by the controller.

The ratio (h1/H) between the distance h1 between the stirring blade 20d located on the lower stage and the bottom 10a of the stirring tank and the height H from the bottom 10a of the stirring tank to the upper end 50a of the material to be stirred 50 is , the discharge flow generated by the stirring blade 20d located in the lower stage goes to the tank bottom 10a, and only the discharge flow generated by the stirring blades 20u and 20m located in the upper and middle stages merge, or the stirring blades located in the middle and lower stages It is preferably 0.20 or more, and 0.21 or more from the viewpoint of preventing the inside of the stirring tank 10 from being divided into two by the merging of only the discharge flows generated by 20m and 20d, resulting in a decrease in mixing performance. more preferably 0.22 or more. From the viewpoint of preventing deterioration of mixing performance, it is preferably 0.30 or less, more preferably 0.28 or less, and even more preferably 0.26 or less (Fig. 1 reference). Specifically, the ratio of the distance h1 between the stirring blade 20d located at the lower stage and the bottom 10a of the stirring tank to the height H from the bottom 10a of the stirring tank to the upper end 50a of the object 50 to be stirred ( h1/H) is preferably from 0.20 to 0.30, more preferably from 0.21 to 0.28, and even more preferably from 0.22 to 0.26. The height H from the tank bottom 10a to the upper end 50a of the object 50 to be stirred means the height from the lower end of the inner surface of the tank bottom 10a to the upper end 50a of the object 50 to be stirred. The height H is measured in a state in which the upper end surface of the material to be stirred 50 is flat without rotating the stirring blade.

The ratio of the distance h4 between the stirring blade 20u located on the upper stage and the upper end 50a of the object to be stirred 50 to the height H from the bottom 10a of the stirring tank to the upper end 50a of the object to be stirred 50 (h4/H) is preferably 0.19 or more, from the viewpoint of preventing the upper end face of the object to be stirred 50 from being greatly disturbed and the stirring blade 20u located in the upper stage from being exposed from the upper end 50a of the object to be stirred 50. 0.25 or more is more preferable, and even if a flow pattern is obtained in which the respective discharge flows generated by the three stages of stirring impellers 20u, 20m, and 20d are merged, the merged flow does not reach the top of the stirring vessel 10. However, from the viewpoint of preventing the mixing performance from deteriorating, it is preferably 0.30 or less, more preferably 0.27 or less (see FIG. 1). Specifically, the ratio of the distance h4 between the upper stirring blade 20u and the upper end 50a of the object to be stirred 50 to the height H from the bottom 10a of the stirring tank to the upper end 50a of the object to be stirred 50 ( h4/H) is preferably 0.19 or more and 0.30 or less, more preferably 0.25 or more and 0.27 or less.

If the ratio (H/D) of the height H from the tank bottom 10a of the stirring tank to the upper end 50a of the material to be stirred 50 and the inner diameter D of the stirring tank is too large, the three-stage stirring blades 20u, 20m, and 20d will cause Since the discharge flows independently form circulation flows, the mixing performance deteriorates. If the ratio (H/D) of the height H from the tank bottom 10a of the stirring tank to the upper end 50a of the material to be stirred 50 and the inner diameter D of the stirring tank is too small, the peripheral ends of the stirring blades 20u, 20m, and 20d to the wall surface becomes large, and uniform mixing in the radial direction cannot be maintained. Therefore, the ratio (H/D) of the height H to the upper end 50a of the material to be stirred 50 and the inner diameter D of the stirring vessel is 0.95 or more and 1.15 or less, more preferably 0.99 or more and 1.13 or less. It is desirable to

Then, in the stirring device 1 containing the object 50 to be stirred, the rotating shaft 11 is rotated to stir the object 50 to be stirred in the stirring tank 10 .

According to the stirring device 1 of the present embodiment, the distances between the three stages of stirring blades 20u, 20m, and 20d are uneven, and the lower stirring blade 20u has a constant distance from the bottom 10a of the stirring vessel 10. Therefore, when the rotating shaft 11 of the stirring device 1 is rotated to stir the material to be stirred 50 in the stirring tank 10, three stages of stirring blades 20u, 20m, and 20d as shown in FIG. A flow pattern is obtained in which all the resulting discharge streams converge. The discharge flows generated by the respective stirring blades 20u, 20m, and 20d are all merged and then collide with the inner peripheral surface (or baffle plate) of the stirring tank 10 and split vertically, and the downward flow reaches the bottom 10a of the tank. , the mixing performance in the stirring tank 10 can be improved. In addition, since the radial flow type stirring blades 20 having a large shearing force are used, the stirring can be performed while maintaining the shearing force given by the stirring blades 20 to the object 50 to be stirred without increasing the power required for stirring. The mixing performance within the tank 10 can be improved.

In general, the flow state of the material to be stirred can be determined by the stirring Reynolds number Re defined by Equation (2). The stirring Reynolds number Re is a dimensionless number that represents the ratio of the kinetic energy due to inertia of the fluid to the energy lost due to viscosity. Here, ρ is the liquid density (kg/m ³ ), n is the rotation speed (rpm), d is the outer diameter of the stirring blade (m), and μ is the liquid viscosity (Pa·s).

The agitation Reynolds number Re in the present invention is not particularly limited, but when the agitation Reynolds number Re is extremely small, the flow state of the object to be stirred is very weak and the discharge flows are difficult to merge. Therefore, the stirring Reynolds number Re is preferably 4000 or more.

By using the stirring device 1 to stir the material to be stirred 50 in the stirring tank 10, it can be used in various chemical processes. For example, the object to be stirred 50 in the stirring tank 10 can be stirred using the stirring device 1 to perform gas-liquid reaction, emulsification, or solid-liquid dispersion.

Further, the object 50 to be stirred in the stirring vessel 10 can be stirred using the stirring device 1 to produce an emulsion or a suspension. Examples of emulsions that can be produced according to the present embodiment include oil-in-water emulsion compositions, emulsified cosmetics and quasi-drugs, emulsion compositions for food and drink, and emulsified oily foods. Suspensions that can be produced according to this embodiment include, for example, cosmetic slurry compositions, food slurry compositions, ink-pigment mixtures, and the like.

In addition, the object to be stirred 50 containing the enzyme and the substrate can be accommodated in the agitating vessel 10 of the stirring device 1, and the object to be stirred 50 can be stirred to carry out the enzymatic reaction. Thereby, an enzymatic reaction product can be produced. Examples of enzymatic reaction products that can be produced according to this embodiment include polyphenols and fatty acids. Many enzymatic reactions require a gas such as oxygen, or increase the amount of by-products as the enzymatic reaction progresses and change the pH of the reaction solution. In such a case, the object to be stirred 50 can be stirred while supplying the gas from the gas supply pipe 42 installed in the stirring tank 10 or while supplying the pH adjuster from the pipe 41 . Examples of the gas supplied from the gas supply pipe 42 include air, oxygen, nitrogen, carbon dioxide, etc. Examples of the pH adjuster supplied from the pipe 41 include alkali metals such as sodium hydroxide, Alkaline solutions of alkaline earth metal hydroxides, acid solutions of hydrochloric acid, acetic acid, citric acid, phosphoric acid and the like are included.
Examples of enzymatic reactions performed while stirring by the stirring method or stirring device of the present invention include, for example, hydrolysis of tea extract using an enzyme having tannase activity (see Japanese Patent No. 4244230), hydration of fatty acids by lipase, and decomposition.

Although the present invention has been described above based on its preferred embodiments, the present invention is not limited to the above embodiments. For example, in the present embodiment, the three stages of stirring blades 20u, 20m, and 20d are all the same. , or the three-stage stirring blades 20u, 20m, and 20d may be different from each other. In this embodiment, the plurality of blades 22 of the stirring blade 20 are all the same, but the plurality of blades 22 may include blades with different sizes and attachment angles.

In the stirring device 1 according to the present embodiment, the baffle plate 30 extends above the upper end 50a of the object 50 to be stirred, but the upper end of the baffle plate 30 is positioned below the upper end 50a of the object 50 to be stirred. (See FIG. 6(a)). In this embodiment, the lower end of the baffle plate 30 is located above the tank bottom 10a, but the lower end of the baffle plate 30 may extend to the tank bottom 10a along the shape of the tank bottom 10a. Good (see FIG. 6(b)). Also, the baffle plate 30 may be divided in the height direction (see FIG. 6(c)).

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to such Examples.

[Example 1]
Three stages of disk turbine blades having the following dimensions were attached to a stirred vessel having a 10% dish-shaped vessel bottom and an inner diameter of 2100 mm.
Ratio of outer diameter d of stirring blade to inner diameter D of stirring vessel (d/D): 0.333
The ratio of the height b of the stirring blade to the outer diameter d of the stirring blade (b/d): 0.200
The ratio (c/d) of the radial length c of the stirring surface of the impeller and the outer diameter d of the stirring blade: 0.25
Ratio of the length c in the radial direction of the stirring surface of the impeller to the height b of the stirring blade: 1.25
The ratio of the largest projected area A1 to the smallest projected area A2 among the projected areas of the stirring surface of the impeller on the plane parallel to the axial direction of the stirring vessel (A1/A2): 1.00
Angle θ formed between the stirring surface of the impeller and the virtual line parallel to the axial direction of the rotating shaft: 0°

A baffle plate having the following shape and dimensions was attached to the stirring tank.
Shape of baffle plate: Plate-shaped baffle plate Number of baffle plates: 4 Ratio of width s1 of baffle plate to outer diameter d of stirring blade (s1/d): 0.07
Ratio of the width s2 of the gap between the baffle plate and the inner peripheral surface of the stirring tank to the width s1 of the baffle plate (s2/s1): 0

Table 1 shows the amount of material to be stirred, the position of each stirring blade, and the Reynolds number in the stirring apparatus having the stirring vessel and the stirring blades described above. A simulation of stirring a material to be stirred using such a stirring device was performed, and the flow pattern was determined, the mixing performance of the material to be stirred was evaluated, and the average torque value was measured as follows.

<How to distinguish the flow pattern by simulation>
A simulation was performed using general-purpose thermo-fluid analysis software. In the simulation, a three-dimensional incompressible fluid was assumed and the flow field was calculated. From the velocity vector diagram (not shown) of the calculation result, the flow pattern was discriminated by looking at the direction of the flow from each stirring blade. The “three-stage confluence flow pattern (three stages)” means that the discharge flow generated by the lower stirring blade 20d is directed upward, the discharge flow of the upper stirring blade 20u is directed downward, and the three-stage stirring blade It is a flow pattern in which all the discharge flows of are joined. An example of a three-stage confluence flow pattern is shown in FIGS. 7(a) and 7(d). "Upper two-stage confluence flow pattern (upper two stages)" means that the discharge flow generated by the lower stirring blade 20d is directed downward toward the tank bottom 10a, and is generated by the middle and upper stirring blades 20m and 20u. A discharge flow is a flow pattern that merges. FIG. 7B shows an example of the upper two-stage confluence flow pattern. "Lower two-stage confluence flow pattern (lower two stages)" is a flow pattern in which the stirring blade 20d located in the lower stage and the stirring blade 20m located in the middle stage merge, and the discharge flow generated by the stirring blade 20u located in the upper stage is isolated. It's about. An example of the lower two-stage confluence flow pattern is shown in FIG. 7(c).

分離強度Ｓは完全に分離した初期状態で１、完全に均一に混合した状態で０となる。計算では０．２秒毎に各計算セルにおけるトレーサー濃度を出力して分離強度Ｓを求め、トレーサー投入後Ｓ＝０．００１となるまでの時間を混合時間とした。２０秒以降は指数近似式により外挿した。 <Evaluation method of mixing performance of material to be stirred by simulation>
After the calculation was performed until the flow field became steady, the upper 10% of the material to be stirred was set as the tracer (scalar amount), and a tracer mixing simulation was performed for 20 seconds. Mixing time is used as a criterion to evaluate the mixing performance of stirring devices and methods. Mixing time refers to the time required to achieve the specified homogeneity within the material being stirred after the tracer is added. Separation strength S was used to quantify the mixing time in the simulation. The separation strength S is an index representing the non-uniformity of the tracer, and is represented by the following Equation 3.

The separation strength S is 1 in the initial state of complete separation, and 0 in the state of complete uniform mixing. In the calculation, the tracer concentration in each calculation cell was output every 0.2 seconds to obtain the separation strength S, and the mixing time was defined as the time until S=0.001 after the tracer was added. After 20 seconds, the exponential approximation was used for extrapolation.

<Measurement method of torque average value by simulation>
Based on the simulation results, changes in the torque of the stirring shaft over time were output every 0.2 seconds for 20 seconds, and the average value was taken as the torque average value.

[Example 2]
The ratio of the distance h1 between the lower stirring blade and the bottom of the stirring tank to the height H from the bottom of the stirring tank to the upper end of the object to be stirred (h1/H) and the lower stirring blade A simulation was performed in the same manner as in Example 1, except that the ratio (h1/D) of the distance h1 between the bottom of the stirring vessel and the inner diameter of the stirring vessel was changed as shown in Table 1, and the flow pattern and the mixing performance of the material to be stirred was evaluated.

[Comparative Example 1]
Table 1 shows the ratio (h2/h3) of the distance h2 between the lower stage stirring blade and the middle stage stirring blade and the distance h3 between the upper stage stirring blade and the middle stage stirring blade. A simulation was performed in the same manner as in Example 1, except for the changes shown in 1, and the flow pattern was determined, the mixing performance of the material to be stirred was evaluated, and the torque average value was measured.
[Comparative Example 2]
Table 1 shows the ratio (h2/h3) of the distance h2 between the lower stage stirring blade and the middle stage stirring blade and the distance h3 between the upper stage stirring blade and the middle stage stirring blade. A simulation was performed in the same manner as in Example 1, except for the changes shown in 1, to evaluate the flow pattern discrimination and the mixing performance of the material to be stirred.
[Comparative Example 3]
The ratio (h2/h3) of the distance h2 between the lower stage stirring blade and the middle stage stirring blade and the distance h3 between the upper stage stirring blade and the middle stage stirring blade is expressed. A simulation was performed in the same manner as in Example 1, except that the conditions were changed as shown in 1, and the flow pattern was determined and the mixing performance of the material to be stirred was evaluated.

Table 1 shows the determination results of the flow patterns and the measurement results of the mixing time of the material to be stirred in Examples 1 and 2 and Comparative Examples 1 and 3. is shown in FIG. The torque 5-section moving average means the average value of the torque output every 0.2 seconds for 5 sections, that is, for 1 second. As shown in Table 1, in Comparative Examples 1 and 2, the upper two-stage confluence flow pattern (see FIGS. 7(b) and 8(b)) in which the discharge flows generated by the upper and middle stirring blades merge is obtained. In Example 3, the discharge flow generated by the middle and lower stirring blades merged into a lower two-stage converging flow pattern (see FIG. 7(c)), whereas in Examples 1 and 2, three stages A three-stage confluence flow pattern (see FIGS. 7(a) and 8(a)) was obtained in which the discharge flows generated by the respective stirring blades merge.
Therefore, it was found that the stirring methods of Examples 1 and 2 had better uniform mixing properties than the stirring methods of Comparative Examples 1-3. In addition, the stirring methods of Examples 1 and 2 have a shorter mixing time than the stirring methods of Comparative Examples 1 to 3 (see Table 1 and FIG. 9). Furthermore, as shown in FIG. 10, it can be seen that the stirring method of Example 1 has a lower torque average value than the stirring method of Comparative Example 1. Therefore, it was found that the stirring method of Example 1 can improve the mixing performance compared to Comparative Example 1 without requiring a large amount of power.

[Comparative Example 4]
The ratio of the distance h1 between the lower stirring blade and the bottom of the stirring tank to the height H from the bottom of the stirring tank to the upper end of the object to be stirred (h1/H) and the lower stirring blade A simulation was performed in the same manner as in Example 1, except that the ratio (h1/D) of the distance h1 between the bottom of the stirring vessel and the inner diameter of the stirring vessel was changed as shown in Table 2, and the flow pattern and the mixing performance of the material to be stirred was evaluated.
[Comparative Example 5]
The ratio of the distance h1 between the lower stirring blade and the bottom of the stirring tank to the height H from the bottom of the stirring tank to the upper end of the object to be stirred (h1/H) and the lower stirring blade A simulation was performed in the same manner as in Example 1, except that the ratio (h1/D) of the distance h1 between the bottom of the stirring vessel and the inner diameter of the stirring vessel was changed as shown in Table 2, and the flow pattern and the mixing performance of the material to be stirred was evaluated.

Table 2 shows the determination results of the flow patterns and the measurement results of the mixing time of the material to be stirred in Examples 1 and 2 and Comparative Examples 4 and 5. As shown in Table 2, in Comparative Example 4, the lower two-stage confluence flow pattern (see FIG. 7(c)) was obtained. In addition, although Comparative Example 5 has a three-stage confluence flow pattern (see FIG. 7(d)), the confluence circulation flow does not reach the bottom of the tank, and compared to Examples 1 and 2, the uniformity in the tank is low. Mixability is low. Moreover, as shown in Table 2, the stirring methods of Examples 1 and 2 have a shorter mixing time than the stirring methods of Comparative Examples 4 and 5.

[Example 3]
The liquid volume L of the object to be stirred contained in the stirring tank, the height H of the object to be stirred at the top end, the ratio of the height H from the bottom of the stirring tank to the top end of the object to be stirred and the inner diameter D of the stirring tank ( H/D) and the ratio (h1/D) between the distance h1 between the stirring blade located in the lower stage and the bottom of the stirring vessel and the inner diameter D of the stirring vessel (h1/D) was changed as shown in Table 3. A simulation was performed in the same manner as in Example 1 to evaluate the flow pattern and the mixing performance of the material to be stirred.

[Comparative Example 6]
The ratio (h2/h3) of the distance h2 between the lower stage stirring blade and the middle stage stirring blade and the distance h3 between the upper stage stirring blade and the middle stage stirring blade is expressed. A simulation was performed in the same manner as in Example 3, except for the change shown in 3, and the flow pattern was determined and the mixing performance of the material to be stirred was evaluated.

Table 3 shows the determination results of the flow patterns and the measurement results of the mixing time of the material to be stirred in Example 3 and Comparative Example 6. As shown in Table 3, in Comparative Example 6, the upper two-stage converging flow pattern (see FIG. 7(b)) is obtained, whereas in Example 3, the discharge flow generated by each of the three stages of stirring impellers is A three-stage confluence flow pattern (see FIG. 7A) is obtained. Therefore, it was found that the stirring method of Example 3 was better in uniform mixing than the stirring method of Comparative Example 6. Moreover, as shown in Table 3, the stirring method of Example 3 has a shorter mixing time than the stirring method of Comparative Example 6.

[Examples 4 to 6]
A stirring tank with an inner diameter of 2300 mm was used, and the amount of material to be stirred, the position of each stirring blade and the Reynolds number were as shown in Table 4. A simulation was performed in the same manner as in Example 1 except for the above, and the flow pattern was determined and the mixing performance of the material to be stirred was evaluated.

[Comparative Examples 7 to 9]
The ratio of the distance h3 between the stirring blades located in the upper stage and the stirring blades located in the middle stage (h2/h3), the distance h1 between the stirring blades located in the lower stage and the bottom of the stirring vessel and the stirring vessel The ratio of the height H from the bottom of the tank to the upper end of the object to be stirred (h1/H) and the ratio of the distance h1 between the stirring blade located in the lower stage and the bottom of the stirring tank to the inner diameter D of the stirring tank ( A simulation was performed in the same manner as in Examples 4 to 6, except that h1/D) was changed as shown in Table 4, and the flow pattern was determined and the mixing performance of the material to be stirred was evaluated.

Table 4 shows the determination results of the flow patterns and the measurement results of the mixing time of the material to be stirred in Examples 4 to 6 and Comparative Examples 7 to 9. As shown in Table 4, in Comparative Examples 7 to 9, the upper two-stage converging flow pattern (see FIG. 7(b)) is formed, whereas in Examples 4 to 6, the three-stage stirring blades cause A three-stage confluence flow pattern (see FIG. 7(a)) is formed in which the discharged flows merge. Therefore, it was found that the stirring methods of Examples 4 to 6 are better in uniform mixing than the stirring methods of Comparative Examples 7 to 9. Further, as shown in Table 4, the stirring methods of Examples 4-6 have a shorter mixing time than the stirring methods of Comparative Examples 7-9.

[Example 7]
A stirring tank with an inner diameter of 288 mm was used, and the amount of material to be stirred, the position of each stirring blade and the Reynolds number were as shown in Table 5. A simulation was performed in the same manner as in Example 1 except for the above, and the flow pattern was determined and the mixing performance of the material to be stirred was evaluated. In addition, an actual experiment was conducted using a stirring device having the same shape as the stirring device used in the simulation, and flow pattern discrimination and mixing performance were evaluated.

<Discrimination method of flow pattern by actual experiment>
Visualization experiments were performed using the resin bead method to determine flow patterns. The resin bead method involves making colored resin beads accompany a colorless material to be stirred, observing its movement with a high-speed camera, and visually judging the flow pattern by observing the direction of flow from each stirring blade. is. The flow patterns were discriminated into "three-stage confluence flow pattern", "upper two-stage confluence flow pattern", and "lower two-stage confluence flow pattern" in the same manner as the method of distinguishing flow patterns from simulation results.

<Evaluation method of mixing performance of material to be stirred by actual experiment>
An alkali response experiment was conducted to measure the mixing time, which is a criterion for evaluating the mixing performance of the stirring device and stirring method. In the alkali response experiment, an alkaline liquid is dropped as a tracer into a stirring tank, and a pH sensor installed at the bottom of the tank detects the change in pH over time to determine the mixing time. In the experiment, the pH of the liquid in the tank was adjusted to 4.5±0.1, and the NaOH solution was added in a stirred state, and the numerical value output from the pH meter was obtained over time. Sampling was performed at intervals of 0.2 seconds until 300 seconds after the NaOH solution was added. The pH data of each time history was normalized by the values after 0 second and 300 seconds, and then calculated by moving average (5 points). Mixing time was defined as the time until the moving average of normalized pH data first exceeded 0.97.

[Comparative Example 10]
The ratio of the distance h3 between the stirring blades located in the upper stage and the stirring blades located in the middle stage (h2/h3), the distance h1 between the stirring blades located in the lower stage and the bottom of the stirring vessel and the stirring vessel The ratio of the height H from the bottom of the tank to the upper end of the object to be stirred (h1/H) and the ratio of the distance h1 between the stirring blade located in the lower stage and the bottom of the stirring tank to the inner diameter D of the stirring tank ( A simulation and an actual experiment were conducted in the same manner as in Example 7 except that h1/D) was changed as shown in Table 5, and the flow pattern and mixing performance of the material to be stirred were evaluated.

Table 5 shows the determination results of the flow patterns and the measurement results of the mixing time of the material to be stirred in Example 7 and Comparative Example 10. As shown in Table 5, in both the simulation and the actual experiment, in Comparative Example 10, the upper two-stage confluence flow pattern (see FIG. 7(b)) was obtained, whereas in Example 7, the three-stage A three-stage confluence flow pattern (see FIG. 7(a)) is formed in which the discharge flows generated by the respective stirring blades merge. Therefore, it was found that the stirring method of Example 7 was better in uniform mixing than the stirring method of Comparative Example 10. In addition, as shown in Table 5, the stirring method of Example 10 has a shorter mixing time than the stirring method of Comparative Example 10 in both the simulation and the actual experiment.

[Comparative Example 11]
In Example 1, the simulation was performed in the same manner as in Example 1, except that the dimensions of the stirring blades attached to the stirring vessel were changed as shown in Table 6, and the flow pattern was determined, the mixing time of the stirred material was measured, and the torque A mean value was measured.

Table 6 shows the determination results of the flow pattern, the measurement results of the mixing time of the material to be stirred, and the measurement results of the torque average value of Example 1 and Comparative Example 11, and the torque 5-section moving average of Example 1 and Comparative Example 11 It is shown in FIG. As shown in Table 6 and FIG. 11, Comparative Example 11 has a larger average torque value than Example 1. Therefore, it was found that the stirring method of Example 1 can improve the mixing performance as compared with Comparative Example 11 without requiring a large power.

1 stirring device 10 stirring tank 10a bottom of stirring tank 11 rotating shaft 20u upper stirring blade 20m middle stirring blade 20d lower stirring blade 21 disk 22 blade 23 stirring surface 30 baffle plate 41 pipe 42 Gas supply pipe 50 Material to be stirred 50a Upper end of material to be stirred h1 Distance between lower stirring blade and bottom of stirring tank h2 Distance between lower stirring blade and middle stirring blade h3 Distance between the upper stirring blade and the middle stirring blade H Height from the bottom of the stirring tank to the upper end of the object to be stirred D Internal diameter of the stirring tank

Claims (9)

Housed in the stirring vessel using a stirring device comprising a cylindrical stirring vessel, a rotating shaft arranged along the central axis of the stirring vessel, and a plurality of stirring blades attached to the rotating shaft A stirring method for stirring a liquid object to be stirred,
The stirring blades are all radial flow type stirring blades intermittently provided with a plurality of blades around the rotating shaft, and are mounted in three stages at intervals in the axial direction of the rotating shaft,
Under the conditions satisfying all of the following (1) to ( 6 ),
A stirring method in which the rotating shaft is rotated to stir the object to be stirred.
(1) the distance h2 between the stirring blades located in the lower stage and the stirring blades located in the middle stage, and the distance h3 between the stirring vanes located in the upper stage and the stirring vanes located in the middle stage; A ratio (h2/h3) is 0.50 or more and 0.95 or less.
(2) The ratio of the distance h1 between the stirring blade located in the lower stage and the bottom of the stirring tank to the height H from the bottom of the stirring tank to the upper end of the object to be stirred (h1/H ) is 0.20 or more and 0.30 or less.
(3) The ratio (d/D) between the outer diameter d of the stirring blade and the inner diameter D of the stirring vessel is 0.25 or more and 0.50 or less.
(4) Among the blades of the plurality of stirring blades, the projected area of the blade with the largest projected area on the stirring surface of the blade to the plane parallel to the axial direction of the stirring tank is A1, and the projected area of the blade with the smallest projected area is A1. When the area is A2, the ratio of A1 to A2 (A1/A2) is 1.0 or more and 1.1 or less.
(5) The stirring Reynolds number Re is 4000 or more.
(6) The ratio of the distance h4 between the upper stirring blade and the upper end of the material to be stirred to the height H from the bottom of the stirring vessel to the upper end of the material to be stirred (h4/H ) is 0.19 or more and 0.30 or less. The stirring device has a baffle plate attached to the inner peripheral surface of the stirring vessel,
The ratio (h1/D) of the distance h1 between the stirring blade located in the lower stage and the bottom of the stirring vessel to the inner diameter D of the stirring vessel is 0.190 or more and 0.345 or less. Item 1. The stirring method according to Item 1. 3. The stirring method according to claim 1, wherein the stirring device is used to stir the object to be stirred in the stirring vessel for gas-liquid reaction, emulsification, or solid-liquid dispersion. 4. The stirring method according to any one of claims 1 to 3, wherein the stirring device is used to stir the material to be stirred in the stirring tank to perform an enzymatic reaction. The stirring device has a gas supply pipe installed at the bottom of the stirring tank and a pipe installed at the top of the stirring tank,
5. The enzymatic reaction is performed by stirring the material to be stirred in the stirring vessel while supplying the gas from the gas supply pipe and the liquid from the pipe, or both. The stirring method described in . A method for producing an emulsion using the stirring method according to claim 3. A method for producing a suspension using the stirring method according to claim 3. A method for producing an enzymatic reaction product using the stirring method according to claim 4 or 5. A stirring device comprising a cylindrical stirring vessel, a rotating shaft arranged along the central axis of the stirring vessel, and a plurality of stirring blades attached to the rotating shaft,
A baffle plate is attached to the inner peripheral surface of the stirring tank,
The stirring blades are all radial flow type stirring blades intermittently provided with a plurality of blades around the rotating shaft, and are mounted in three stages at intervals in the axial direction of the rotating shaft,
Ratio (h2 /h3) is 0.50 or more and 0.95 or less,
The ratio (h1/D) of the distance h1 between the lower stirring blade and the bottom of the stirring vessel to the inner diameter D of the stirring vessel is 0.190 or more and 0.345 or less,
The ratio (d/D) of the outer diameter d of the stirring blade to the inner diameter D of the stirring vessel is 0.25 or more and 0.50 or less,
Among the blades of the plurality of stirring blades, the projected area of the blade with the largest projected area on the plane parallel to the axial direction of the stirring vessel on the stirring surface of the blade is A1, and the projected area of the blade with the smallest projected area is A2. When the ratio of A1 and A2 (A1/A2) is 1.0 or more and 1.1 or less,
The rotating shaft is rotated so that the stirring Reynolds number Re when stirring the object to be stirred is 4000 or more,
The ratio (h4/H) of the distance h4 between the upper stirring blade and the upper end of the material to be stirred to the height H from the bottom of the stirring vessel to the upper end of the material to be stirred is 0 .19 or more and 0.30 or less.

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