JP6754358B2 - Stirrer - Google Patents

Description

The present invention relates to a stirring device having a stirring tank and a stirring blade, and mixing and stirring the liquid filled in the stirring tank.

Stirrers with stirring blades are widely used in various fields such as beverage production and polymer chemistry.
When a stirring device having a stirring blade is used, the liquid to be agitated is injected into the stirring tank and the stirring blade provided in the stirring tank is rotated to stir the liquid to be agitated. As the stirring blade, a paddle type stirring blade or a screw type stirring blade is generally used.
For example, in a stirring device used in the field of beverage production, one or a plurality of paddle type or screw type stirring blades are arranged on a rotating shaft, and the rotating shaft is arranged at the center of a cylindrical stirring tank or at a position deviated from the center. doing.

Here, when the stirring blade is rotated to stir the liquid, bubbles may be generated on the surface of the liquid (so-called "foaming"). When the amount of such bubbles generated is large (when the bubbles are intense), the generated bubbles do not disappear even after the stirring is completed, and the air contained in the bubbles acts as a heat insulating agent. Therefore, the bubbles are stirred after stirring. Even if the liquid is sterilized by heating, heat is not sufficiently transferred and sterilization may be insufficient. Further, when the agitated liquid is filled, the remaining bubbles may enter the filled product and cause a capacity shortage.
Therefore, in the stirring device, it is required to suppress the generation of bubbles during stirring.

In a conventional stirring device having a paddle type stirring blade, when the liquid level of the liquid to be agitated is substantially equal to, for example, the vertical position of the stirring blade (when the paddle type stirring blade is suspended on the liquid level), , It has been confirmed that foaming becomes intense. Therefore, in the paddle type stirring blade, in order to suppress foaming, the stirring blade is completely immersed in the liquid to be stirred so that the stirring blade does not come into contact with the liquid surface to be stirred. There are cases where more liquid to stir must be added than required. Further, a conventional stirring device having a screw type stirring blade has the same problem.
However, since the amount of liquid exceeding the required amount is discarded after stirring, there is a problem that the amount of liquid loss increases. In order to solve this problem, it has been required that foaming can be suppressed regardless of the amount of liquid injected into the stirring tank, and that the required stirring power can be maintained.
However, a stirring device capable of suppressing the generation of bubbles during stirring and maintaining the required stirring force has not yet been proposed regardless of the amount of liquid filled in the stirring tank.

As another conventional technique, there is a conventional technique having a plate-shaped (so-called "comb-shaped") stirring blade having an opening (Patent Document 1), but the position relative to the stirring tank and the stirring tank Depending on the shape and the like, the required stirring performance may not be exhibited, or a large amount of bubbles may be generated and the amount of dissolved oxygen in the formulation may exceed the permissible limit. Therefore, regardless of the amount of liquid filled in the stirring tank, it is not possible to suppress the generation of bubbles during stirring and to maintain the required stirring power.

Japanese Unexamined Patent Publication No. 8-215554

The present invention has been proposed in view of the above-mentioned problems of the prior art, and produces a preparation or the like in which the amount of dissolved oxygen is small by suppressing foaming of the liquid during stirring regardless of the volume of the liquid in the stirring tank. It is an object of the present invention to provide a stirring device capable of exhibiting the required stirring performance for liquids having different volumes.

The stirring device (100) of the present invention is a stirring device having a stirring tank (1) and stirring blades (2).
The rotation shaft (20) of the stirring blade (2) extends to the central shaft (Lo) of the stirring tank (1).
The stirring blade (2) is entirely flat and has an opening (22) extending in the vertical direction, and the radial outer edge of the stirring blade (2) extends in the vertical direction. Ori,
The radial dimension (width dimension D2) of the stirring blade (2) is 60% or less of the inner diameter (D1) of the stirring tank.
The bottom surface (12) of the stirring tank (1) has a conical shape.
It is characterized by having a rotation mechanism (3) that rotates the rotation shaft (20) of the stirring blade (2) at a non-constant speed that repeats low speed and high speed at regular intervals.
In the present invention, the ratio of the rotation speed of the stirring blade (2) at low speed and high speed is preferably 1: 1.5 to 1: 4.

In the present invention, the bottom surface (12) of the stirring tank (1) has a conical shape, and the central axis (Lc) of the conical shape is inclined with respect to the central axis (Lo) of the stirring tank (1) (so-called "" It is preferably an inclined conical "shape).

In the present invention, the radial dimension (width dimension D2) of the stirring blade (2) is preferably 40 to 60% of the inner diameter (D1) of the stirring tank.
The vertical dimension (H2) of the stirring blade (2) is preferably 100 to 300% of the radial dimension (width dimension D2).
Further, the stirring device of the present invention preferably has only one stirring blade (2).

In the present invention, the area of the opening (22) with respect to the stirring blade (2) (total area of the stirring blade 2: here, the area of the stirring blade 2 assuming that the opening 22 is not opened). Is preferably 20 to 50%.
Further, a region other than the opening (22) in the stirring blade (2) and extending continuously in the vertical direction (a portion corresponding to "comb teeth" in the comb-shaped stirring blade: so-called "comb". "(24)) is preferably provided with 4 to 6 lines.

In the present invention, it is preferable that the lower end portion of the stirring blade (2) extends parallel to the region of the bottom surface (12) of the stirring tank (1) having the largest inclination angle with respect to the horizontal plane.

In carrying out the present invention, the rotation mechanism (3) that rotates the rotation shaft (20) of the stirring blade (2) at a non-constant speed is a mechanical rotation mechanism even if it has an electronically controlled rotation control mechanism. There may be. If it is a mechanical rotation mechanism, for example, a mechanism using an elliptical gear or a non-circular gear (for example, an egg-shaped gear) can be adopted.

According to the present invention having the above-described configuration, since the rotation shaft (20) of the stirring blade (2) extends to the central shaft (Lo) of the stirring tank (1), the rotation shaft (20) stirs. Foaming can be suppressed as compared with the case where the tank (1) is biased with respect to the central axis (Lo).
The stirring blade (2) of the present invention has a flat plate shape as a whole, but has an opening (22) extending in the vertical direction. Therefore, the stirring blade (2) is placed in a liquid for stirring. The resistance at the time of rotation does not become too large, the liquid in the stirring tank (1) is prevented from rotating together with the stirring blade (2), and deterioration of the stirring performance can be prevented.
According to the present invention, since the radial outer edge of the stirring blade (2) extends in the vertical direction, it is compared with the case where the stirring blade (2) is inclined with respect to the rotation axis (20). Therefore, foaming can be suppressed.
Further, the radial dimension (width dimension D2) of the stirring blade (2) is 60% or less of the inner diameter (D1) of the stirring tank, and the generation (foaming) of bubbles is suppressed without deteriorating the stirring performance. Therefore, the amount of dissolved oxygen in the liquid after stirring is suppressed.

The bottom surface (12) of the stirring tank (1) of the present invention has a conical shape and can suppress the generation of bubbles during stirring.
Further, by rotating the rotating shaft (20) of the stirring blade (2) at a non-constant speed by the rotating mechanism, co-rotation and the like are suppressed, and sufficient stirring performance can be obtained.
As a result, according to the present invention, it is possible to produce a formulation having high stirring performance, suppressing liquid foaming during stirring, and having a small amount of dissolved oxygen without using a baffle or a baffle plate. Moreover, the required stirring performance can be exhibited for liquids having different volumes.

In the present invention, the bottom surface (12) of the stirring tank (1) has a conical shape, and the central axis (Lc) of the conical shape is inclined with respect to the central axis (Lo) of the stirring tank (1) (so-called "" Since it has a "tilted conical" shape), it is not necessary to place the injection / discharge port directly under the stirring tank while maintaining the effect of suppressing foaming during stirring, improving workability during liquid feeding. Can be done.
Alternatively, in the present invention, if the radial dimension (D2) of the stirring blade (2) is 40 to 60% of the inner diameter (D1) of the stirring tank, the stirring blade (2) is too small and the stirring performance deteriorates. Is prevented, and the viscous resistance due to the liquid existing between the side wall portion (11) of the stirring tank (1) and the radial outer end portion of the stirring blade (2) is suppressed, and sufficient stirring performance is obtained. Can be done.

Then, in the present invention, if the vertical dimension (H2) of the stirring blade (2) is set to 100 to 300% of the radial dimension, the vertical dimension of the comb-shaped stirring blade (2) becomes too short, and the stirring tank It is possible to prevent the situation where the liquid existing in the upper region of (1) is not agitated by the comb-shaped agitating blade (2). At the same time, since the vertical dimension (H2) of the stirring blade (2) is prevented from becoming too large, the stirring blade (2) is housed in the inner space of the stirring tank (1) and the mirror (13). Can be done.
Further, since the vertical dimension (H2) of the stirring blade (2) is prevented from becoming too large, the upper portion of the stirring blade (2) is present in the region where the liquid does not exist, and the upper portion of the stirring blade (2) is present. It can be prevented that the air is not immersed in the liquid and only agitates the air.
Further, if the stirring device of the present invention is configured to have only one stirring blade (2), the amount of bubbles generated during stirring is suppressed, and the amount of dissolved oxygen in the prepared product after stirring exceeds the reference value. It is possible to prevent it from being lost.

Here, in the present invention, if the area of the opening (22) is 20 to 50% with respect to the stirring blade (2), that is, it is assumed that the opening (22) is not opened. If the area of the opening (22) is 20 to 50% with respect to the area of (2), the area of the opening (22) with respect to the stirring blade (2) is too small (less than 20%). Therefore, the resistance when rotating the stirring blade (2) does not become too large, and the liquid in the stirring tank (1) is suppressed from rotating together with the stirring blade (2). , It is prevented that the stirring performance is deteriorated.
On the other hand, since the area of the opening (22) is not too large (greater than 50%) with respect to the stirring blade (2), the region (the portion other than the opening) in the stirring blade (2) for stirring the liquid. ) Will not be too small, and the situation where the liquid is not sufficiently agitated and mixed even if the stirring blade (2) is rotated is prevented.

In addition to this, a region other than the opening (22) in the stirring blade (2) and extending continuously in the vertical direction (a portion corresponding to "comb teeth" in the comb-shaped stirring blade: If 4 to 6 so-called "combs" 24) are provided, there is an inconvenience due to too few combs (24) (increased resistance to rotate the stirring blade 2 and the liquid in the stirring tank 1). Rotation and stirring performance are reduced) can be prevented. At the same time, it is possible to prevent a situation in which the width dimension of the portion (comb (24)) extending in the vertical direction becomes too small and is bent and deformed due to resistance during stirring.

It is a front sectional view which shows the stirring apparatus which concerns on embodiment of this invention. It is a front view of the stirring blade in an embodiment. It is a side view corresponding to the front view of FIG. It is explanatory drawing explaining the shape of the bottom part of the stirring tank in embodiment. It is a top view explaining the paddle type stirring blade used in the experimental example. It is a front view of the paddle type stirring blade of FIG. It is a top view of the comb-shaped stirring blade used in the experimental example. It is a front view of the comb-shaped stirring blade of FIG. It is a top view explaining the comb-shaped stirring blade with a twisted outer peripheral edge part. It is a front view of the comb-shaped stirring blade of FIG. It is explanatory drawing explaining the bottom surface of one-sided flow. It is explanatory drawing explaining the bottom surface of a cone. It is a top view which shows the stirring blade which added the reinforcing material.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
In FIG. 1, the stirring device according to the embodiment of the present invention is indicated by reference numeral 100 as a whole.
In FIG. 1, the stirring device 100 includes a stirring tank 1, a stirring blade 2, and a rotary blade rotation mechanism 3, and the rotary blade rotation mechanism 3 includes an electric motor 31 and a non-uniform speed rotation mechanism 32. The non-constant speed rotation mechanism 32 is a mechanical rotation mechanism that rotates the rotating shaft 20 of the stirring blade 2 at a non-constant speed. For example, a mechanism using an elliptical gear or a non-circular gear (for example, an oval gear) is adopted. Can be done.
As the non-constant velocity rotation mechanism, not only a mechanical rotation mechanism but also, for example, an electronically controlled rotation control mechanism can be used.

The stirring tank 1 has a cylindrical side wall portion 11, a bottom surface (hereinafter, referred to as “bottom portion”) 12 connected to the lower end of the side wall portion 11, and a mirror 13 formed at the upper end of the side wall portion 11. There is.
A rotary blade rotation mechanism 3 is provided above the upper mirror 13 via members indicated by reference numerals 4 and 5. The rotary blade rotation mechanism 3 includes an electric motor 31 and an unequal velocity rotation mechanism 32, and although not specified, the output shaft of the electric motor 31 is connected to the input shaft of the unequal velocity rotation mechanism 32 and is unequal. The output shaft of the fast rotation mechanism 32 is connected to the rotation shaft 20 of the stirring blade 2.
The stirring tank 1 is supported by the outer body plate 6, and a plurality of legs 7 are provided below the outer body plate 6.
In the stirring device 100 shown in FIG. 1, reference numeral 16 indicates an injection / discharging port for injecting the fluid to be agitated into the stirring tank 1 and discharging the stirred fluid from the stirring tank 1. Further, reference numeral 15 indicates a flow path in which the fluid to be agitated is injected into the stirring tank 1 and the stirred fluid is discharged from the stirring tank 1, and the injection / discharging flow path 15 communicates with the injection / discharging port 16. There is.

The rotating shaft 20 of the stirring blade 2 is arranged so as to coincide with the central axis Lo of the stirring tank 1 (indicated by the alternate long and short dash line in FIG. 1). Further, the rotating shaft 20 of the stirring blade 2 is not biased outward in the radial direction with respect to the central axis Lo of the stirring tank 1.
According to the inventor's experiment, when the rotating shaft 20 of the stirring blade 2 is deviated from the central axis Lo of the stirring tank 1, the rotating shaft 20 of the stirring blade 2 is aligned with the central axis Lo of the stirring tank 1. It has been confirmed that foaming is more intense than when it is done.
In FIG. 1, reference numeral 12I is a cooling water supply port at the bottom 12, reference numeral 12E is a cooling water discharge port at the bottom 12, reference numeral 14I is a cooling water supply port on the side surface of the stirring tank 1, and reference numeral 14E is a side surface of the stirring tank 1. Each of the cooling water discharge ports is shown, and reference numeral 51 indicates a cooling water circulation pipe. Depending on the type of fluid to be agitated, if the fluid temperature rises during agitation, the quality of the agitated formulation may deteriorate. Cooling water supply ports 12I and 14I, cooling water discharge ports 12E and 14E, and cooling water circulation in order to suppress an increase in the temperature of the agitated fluid by supplying and circulating cooling water in order to prevent such deterioration. A water pipe 51 is provided. It is also possible to inject hot water instead of cooling water here to warm the formulation.

Based on FIGS. 2 and 3, the stirring blade 2 will be described with reference to FIG.
In FIGS. 2 and 3, the stirring blade 2 has a symmetrical shape with respect to the center line Lc2 shown by the alternate long and short dash line in FIG. Here, the center line Lc2 overlaps with the central axis Lo (see FIG. 1) of the stirring tank 1 and extends.
The stirring blade 2 is a so-called "comb-shaped" stirring blade, and is formed so that the outer shell line of the flat plate-shaped member has a pentagonal shape. In FIGS. 2 and 3, the pentagonal flat plate shape is formed. The entire member is indicated by reference numeral 21. A plurality of openings 22 are formed in the stirring blade 2, and each of the openings 22 is formed in a rectangular shape (strip shape). The openings 22 are formed by, for example, press punching or fusing. It will be processed.
Here, the word "flat plate" indicating the shape of the stirring blade 2 is configured so that the shape of the stirring blade 2 with a reinforcing material added to the back surface and the thickness of a part of the stirring blade 2 are different from those of other parts. The purpose is to include the shaped shape. For example, FIG. 13 shows a state in which the reinforcing member 148 is added to the stirring blade 2.

In FIG. 2, the stirring blade 2 is formed with openings 22 (six in total) in three rows in the horizontal direction and two rows in the vertical direction. The vertical dimension of each of the openings 22 is much longer than the horizontal dimension. A plurality of rectangular notches 23 are formed in the upper and lower ends of the stirring blade 2. Regarding the position in the left-right direction in FIG. 2, the opening 22 and the notch 23 coincide with each other. As a result, in FIG. 2, on the stirring blade 2, four vertical crosspieces (comb) 24 extending in the vertical direction and three horizontal rails 25 extending in the horizontal direction intersect and are integrally formed. Has been done.
As shown in FIG. 2, the stirring blade 2 has an outer peripheral edge portion 21s (radial outer edge portion of the stirring blade 2) extending in the vertical direction. In other words, the outer peripheral edge portion 21s of the stirring blade 2 (the radial outer edge portion of the stirring blade 2) is not twisted with respect to the rotating shaft 20. “Twist” means that, as shown in FIG. 9, the width of the comb (vertical rail) 241D is twisted at an angle δ with respect to the radial direction Lh. As expected. If the outer peripheral edge is twisted as in the stirring blades shown in FIGS. 9 and 10, the amount of foaming increases.
Further, as shown in FIG. 3, the thickness dimension t21 of the stirring blade 2 is set to be smaller than the outer diameter d20 of the rotating shaft 20. Here, when the reinforcing member 148 is added to the stirring blade 2 (for example, FIG. 13), the thickness dimension of the portion may be the outer diameter d20 or more of the rotating shaft 20.

As shown in FIG. 1, the width dimension D2 of the stirring blade 2 is smaller than the inner diameter D1 of the stirring tank 1 and is set to 60% or less.
More specifically, the width dimension D2 (diameter direction dimension) of the stirring blade 2 is set to 40 to 60% of the inner diameter D1 of the stirring tank 1.
If the width dimension D2 of the stirring blade 2 is less than 40% of the inner diameter D1 of the stirring tank 1, the stirring performance deteriorates. On the other hand, if the width dimension D2 of the stirring blade 2 is larger than 60% of the inner diameter D1 of the stirring tank 1, the liquid in the stirring tank 1 is difficult to mix and stir, and the amount of foaming increases to increase the dissolved oxygen concentration. Will be high.

In FIG. 1, the bottom 12 of the stirring tank 1 has an inclined conical shape. The inclined conical shape is the shape indicated by reference numeral 12 (bottom of the stirring tank 1) in FIG. 4 (2), and is a so-called “inclined conical” shape.
In the case of a normal conical shape, as shown in FIG. 4 (1), the central axis of the conical shape (the axis shown by the dotted line extending in the vertical direction in FIG. 4 (1)) is the vertical axis. Match. On the other hand, in the "tilted conical" shape shown in FIG. 4 (2), the conical central axis Lc (the axis shown by the dotted line in FIG. 4 (2)) as a rotating body figure becomes the central axis Lo of the stirring tank 1. On the other hand, it is tilted (tilt angle θ). In FIG. 1, θ is 6.5 ° and α is 85 °.
In addition, not only in FIG. 4 (2) but also in FIG. 1, the central axis Lc of the inclined cone forming the bottom surface 12 of the stirring tank 1 does not match the central axis Lo of the stirring tank 1. The inclined conical shape of the bottom surface 12 is a conical shape that is asymmetric with respect to the central axis Lo.

In FIG. 4 (2), the angle formed by the inclined central axis Lc and the central axis Lo of the stirring tank 1 is defined as 2α, where the angle of the inclined conical surface forming the bottom surface 12 of the stirring tank 1 is 2α. Assuming that the inclination angle θ is set, the numerical value of α and the inclination angle θ are set on a case-by-case basis depending on various stirring conditions, but α is particularly preferably 75 to 88 °.
In FIG. 2, if the angle formed by the lower end of the stirring blade 2 and the center line Lc2 of the stirring blade 2 (corresponding to the central axis Lo of the stirring tank 1) is β, then FIGS. 1 and 4 (2). As is clear from, β = α−θ. As shown in FIG. 1, the lower end portion of the stirring blade 2 extends parallel to the steep slope of the bottom surface 12 of the stirring tank 1 (the slope in the region on the left side of FIG. 1).
In FIGS. 2 and 3, reference numeral 26 is an impeller boss through which the rotating shaft 20 penetrates, and is supported by a known means with respect to the rotating shaft 20.

In FIG. 2, the vertical dimension H2 of the stirring blade 2 is preferably set in the range of 100% to 300% with respect to the width dimension D2.
If the ratio is too large (for example, more than 300%), the vertical dimensions (vertical dimension, vertical dimension) of the stirring blade 2 become too large, so that the stirring blade 2 can be accommodated in the stirring tank 1. It may not be possible. Further, if the vertical dimension of the stirring blade 2 is increased, the upper region of the stirring blade 2 is not immersed in the liquid to be agitated, and the region only stirs the air, which is wasted.
On the other hand, when the vertical dimension H2 of the stirring blade 2 is less than 100% of the width dimension D2, the vertical dimension H2 of the stirring blade 2 becomes too short, and the liquid existing in the upper region of the stirring tank 1 is stirred. There is a risk that the blade 2 will not stir.
Further, the position of the stirring blade 2 on the vertical axis is preferably closer to the bottom surface 12 so that stirring can be performed even when the amount of the object that can be stirred is small.

The stirring device of the present invention is preferably provided with one stirring blade 2.
When a plurality of stirring blades 2 are installed (for example, when two stirring blades having four combs on the central axis are installed separately on the upper and lower sides), the amount of bubbles generated increases and the dissolved oxygen in the formulation after stirring increases. The amount may exceed the standard value. Therefore, the stirring device 100 according to the illustrated embodiment includes only one comb-shaped stirring blade.

Here, the area of the opening 22 is larger than the area of the entire stirring blade 2 (the area surrounded by the outer shell line of the stirring blade 2: the area of the stirring blade 2 when it is assumed that the opening 22 is not provided). The ratio is preferably 20% to 50%.
In the comb-shaped stirring blade, if the area of the opening 22 is less than 20% of the total area of the stirring blade 2, the opening 22 is too small, and the amount of liquid passing through the opening 22 is also small. , The resistance when rotating the comb-shaped stirring blade 2 in the liquid for stirring becomes too large. Then, the liquid in the stirring tank 1 rotates together with the comb-shaped stirring blade 2, so that the stirring performance deteriorates.
On the other hand, when the area of the opening 22 is larger than 50% with respect to the area of the entire stirring blade 2, the area of the portion other than the opening 22 (the area of the portion for stirring the liquid) in the comb-shaped stirring blade 2 is small. Even if the comb-shaped stirring blade 2 is rotated, the liquid is not sufficiently stirred and mixed because it becomes too much.

The number of vertical rails 24 of the stirring blade 2 is preferably 2 to 6, and particularly preferably 4 to 6. As is clear from FIG. 2, the opening is divided into two regions in the vertical direction.
In the area other than the opening, 2 to 6 parts 24 (parts corresponding to "comb teeth" in the comb-shaped stirring blade: vertical crosspieces) extending continuously in the vertical direction are formed. It is preferable that 4 to 6 places are formed. In FIG. 2, four portions “vertical rails” 24 extending in the vertical direction are formed.
Here, since the comb-shaped stirring blade 2 is formed symmetrically with the rotation axis 20 as the axis of symmetry, the portion extending in the vertical direction (the portion corresponding to the "comb tooth" in the comb-shaped stirring blade) 24 The number of is always an even number.

The comb-shaped stirring blade 2 must always have an opening 22 formed. This is because, as described above, the resistance when rotating in the liquid becomes too large, and the liquid in the stirring tank 1 rotates together with the comb-shaped stirring blade.
As described above, since the number of vertically extending portions 24 (vertical bars corresponding to "comb teeth" in the comb-shaped stirring blade) is always an even number, the vertically extending portions 24 The fact that the number of 24 is less than two means that the opening 22 is not formed, which causes the above-mentioned inconveniences (increased resistance when the stirring blade 2 rotates, co-rotation of the liquid in the stirring tank 1). It will occur.
On the other hand, if there are more than six portions 24 extending in the vertical direction (parts corresponding to "comb teeth" in the comb-shaped stirring blade: vertical rails), the width dimension of the vertical rails 24 becomes too small. The rigidity of the stirring blade 2 is insufficient, and there is a risk that the stirring blade 2 will be bent and deformed due to resistance during stirring. The number of openings 22 is preferably 2, 6 or 10.
In the illustrated embodiment, the overall shape (outer shell shape) of the stirring blade 2 is pentagonal, but it may be rectangular or trapezoidal.

In FIG. 1, the non-constant velocity stirring mechanism 32 is configured so that the rotation speed of the rotation shaft 20 of the stirring blade 2 does not become a constant speed (uniform rotation speed).
A conventionally known mechanism can be applied to the non-constant velocity stirring mechanism 32. For example, a gear train using non-circular and asymmetrical gears can form a non-constant velocity stirring device. It is also possible to make the rotation speed of the rotation shaft 20 of the stirring blade 2 non-uniform by electronic control.

Here, in the non-constant velocity stirring mechanism 32, the ratio of the rotation speed at low speed to the rotation speed at high speed is preferably in the range of 1: 1.5 to 1: 4, and 1: 1.5 to 1: 3. In particular, 1: 1.5 to 1: 2.5 is preferable.
If the speed ratio of the rotation speed of the non-constant velocity stirring mechanism 32 is close to 1, the velocity becomes almost constant, and the merit of making the non-constant velocity cannot be enjoyed. On the other hand, if the speed ratio is too large, it is difficult to manufacture a mechanism that realizes such non-constant velocity rotational motion.
Here, a structure using a non-circular gear is convenient because the liquid is well mixed.

As shown in FIG. 1, in the illustrated embodiment, the bottom portion 12 of the stirring tank 1 is formed into a conical shape, and the lower end of the stirring blade 2 can be arranged close to the bottom portion 12 of the stirring tank 1. Further, the lower end portion of the stirring blade 2 extends parallel to the steep slope of the bottom surface 12 of the stirring tank 1.
Therefore, even when the amount of liquid to be agitated is small and the liquid is present only in the vicinity of the bottom 12, the rotation of the comb-shaped stirring blade 2 ensures that such a small amount of liquid is agitated and mixed. To.

Various verifications were carried out in Experimental Examples 1 to 4 using the stirring device manufactured based on the above-described embodiment as "Example".
[Experimental Example 1]
Experimental Example 1 is an experiment on the influence of the shape of the stirring blade on the generation of bubbles (so-called “foaming”).
As shown in Table 1 below, foaming was observed for two types of paddle-type stirring blades (“45 ° paddle” and “90 ° paddle”) and one type of comb-type stirring blade (“comb type 1”). ..
Table 1

The paddle-type stirring blades described as "45 ° paddles" in Table 1 are indicated by reference numeral 2A in FIGS. 5 and 6.
In the "45 ° paddle" shown in FIGS. 5 and 6, the direction of the paddle 240 extending in the radial direction of the paddle type stirring blade 2A is, as shown in FIG. 6, with respect to the vertical axis (rotation axis) Lv. It is tilted 45 °. Note that FIG. 6 is shown so that the vertical axis Lv is in the left-right direction.
On the other hand, in the paddle type stirring blade described as "90 ° paddle" in Table 1, the paddle 240 of "45 ° paddle" is arranged horizontally with respect to the vertical axis Lv.
In all the stirring devices having paddle type stirring blades used in the experiment, the stirring blades are installed at two places, the lower part and the vicinity of the center of the stirring tank.

The comb-shaped stirring blades described as "comb-shaped 1" in Table 1 are indicated by reference numerals 2C in FIGS. 7 and 8.
In FIGS. 7 and 8, the outermost comb (vertical rail) 241C in the radial direction (horizontal direction in FIGS. 7 and 8) of the comb-shaped stirring blade 2C extends in a direction parallel to the (rotation axis) Lv direction. Moreover, the width direction of the plate of the comb (vertical rail) 241C extends in the radial direction. Further, the "comb type 1" has four combs, and the lower end portion of the stirring blade is parallel to the horizontal plane on the bottom surface of the stirring tank. The vertical dimension of the stirring blade is 200% of the radial dimension, the area of the opening with respect to the stirring blade is 38%, and the radial dimension of "comb type 1" in Experimental Example 1 is 50% of the inner diameter of the stirring tank. ..
Hereinafter, all the stirring devices having a comb-shaped stirring blade used in the experiment have one stirring blade.

The bottom surface shape of the stirring tank used in Example 1 is the "conical" shown in FIG. In FIG. 12, the bottom surface B1 of the stirring tank has a normal conical shape. In the "conical" in Table 1, as shown in FIG. 12, when the outlet E1 is formed in the center of the bottom of the downwardly convex conical shape, and the liquid in the stirring tank flows out from the outlet E1, the liquid is released. It flows from all directions of 360 ° (only arrows A2 and A3 are shown in FIG. 12) toward the outlet E1, and does not flow in only one direction.
The stirring pattern is constant velocity stirring, and the respective rotation speeds are as shown in Table 1. The rotation speed was set so that the required stirring power required to rotate the stirring blade was constant. The rotating shaft is attached to the center of the stirring tank (center shaft position).

評価点（評価ランク）は、５段階に分けられ（ランク数が上がるに従って撹拌状態は悪化する）、各ランクごとに評価するべき要点が規定されている。The evaluation criteria in Experimental Example 1 are shown in Table 2 below. In Experimental Example 1, water was used as the object to be stirred.
Table 2

The evaluation points (evaluation ranks) are divided into five stages (the stirring state deteriorates as the number of ranks increases), and the points to be evaluated for each rank are defined.

The results of Experimental Example 1 are shown in Table 3 below. In addition, "full amount" and "stirring blade surface water level" mentioned here indicate the water level in the stirring tank, and "full amount" means the state where the stirring blade is completely immersed in the liquid, and "stirring blade". The "surface water level" means a state in which the upper end of the stirring blade and the liquid level are substantially equal (the liquid level is near the upper end of the stirring blade (slightly below the upper end)).
Table 3

From Table 3, in the paddle type stirring blades (45 ° paddle, 90 ° paddle), when the stirring blade is located at approximately the same level as the liquid level (stirring blade surface water level), the bubbling rank is 2 or It is 3.5, and foaming may occur if stirring is continued.
On the other hand, in the comb-type stirring blade (comb type 1), the water surface is only a gentle rotating flow wave regardless of whether the stirring blade is completely immersed in the liquid or the upper end of the stirring blade and the liquid level are approximately equal. Not observed.
Therefore, according to Experimental Example 1, it was confirmed that if a comb-shaped stirring blade is used, stirring can be performed while preventing foaming regardless of the amount of the liquid to be stirred.

[Experimental Example 2]
In Experimental Example 2, the influence of the shape of the bottom surface of the stirring tank on foaming was verified.
The conditions of Experimental Example 2 are as shown in Table 4 below. The experimental method and evaluation method in Experimental Example 2 are the same as those in Experimental Example 1 described above.
Table 4

The stirring blade used in this experimental example is the same as the "comb type 1" of experimental example 1, and in experimental example 2, the radial dimension is 50% of the inner diameter of the stirring tank.
The bottom surface shape described as “one-sided flow” in Table 4 is shown in FIG. In FIG. 11, one outlet E is formed in the vicinity of the cylindrical side wall portion S on the bottom surface B of the stirring tank, and when the liquid in the stirring tank flows out from the outlet E, the liquid is indicated by an arrow. As shown by A1, it is configured to flow out in only one direction.
The stirring pattern is constant velocity stirring, and the respective rotation speeds (constant stirring required power) are shown in Table 4. The rotating shaft of the stirring blade was attached in a state of being deviated from the center line of the stirring tank (eccentric shaft position), and the experiment was conducted under the condition that foaming was likely to occur.

The results of Experimental Example 2 are shown in Table 5 below.
Table 5

According to the results shown in Table 5, "when the stirring blade is approximately equal to the liquid level (water level on the stirring blade surface), the foaming of the one-sided flow bottom (Test Example 4) is rank 3 (Table 2). In the conical bottom (Test Example 5), the bubbling is ranked 2 (Table 2). Therefore, when a comb-shaped stirring blade is used, the "conical bottom" is better than the "single flow bottom". , It was confirmed that foaming was further improved.

[Experimental Example 3]
In Experimental Example 3, the case where the stirring blade was rotated at a constant velocity and the case where the stirring blade was rotated at a non-constant velocity were compared. The "comb-shaped stirring blade" used in Comparative Example 1 and Example 1 is the same as the "comb-shaped stirring blade" used in Experimental Example 1, and the diametrical dimension is 50% of the inner diameter of the stirring tank.
Under the conditions shown in Table 6 below, the experiment was conducted with the required power for stirring constant. In Experimental Example 1, a rotation mechanism (non-constant velocity stirring) using a pair of non-circular gears was used. The rotation of the stirring blade changes from low speed to high speed at half rotation, and from high speed to low speed at half rotation, and the ratio of the rotation speed at low speed to the rotation speed at high speed is 1: 1.75. This device has a structure in which a pair of oval gears are engaged, and the gears connected to the power (motor) rotate at a constant speed, so that the gears connected to the rotating shaft of the other stirring blade are unequal. Make a fast rotation. Therefore, Table 6 shows the number of rotations of the gears rotating at a constant speed.
In Table 6 and below, the term "control" refers to a tank using a paddle-type stirring blade that has been generally used during preparation and culturing during beverage production, and the stirring blade is 45. ° It has the same structure as the paddle.
In addition, the bottom shape and shaft position of the stirring tank are shown in Table 6 and are the same as those described in Experimental Examples 1 and 2.
Table 6

In Experimental Example 3, the case where the stirring blade was completely immersed in the liquid (full amount) and the case where the upper end of the stirring blade and the liquid level were substantially equal (water level on the stirring blade surface) were performed.
In Experimental Example 3, the experimental methods of four items shown in Table 7 below (confirmation of poorly mixed portion, confirmation of mixed state, measurement of dissolved oxygen, measurement of foaming amount) are adopted.
In the "Confirmation of mixing state" column of Table 7, the numerical values "(1.5)", "(1)", and "(0.3)" indicate the mixing ratio. That is, the mixing ratio of syrup, yogurt and calcium lactate solution is 1.5: 1: 0.3 (about 5: 3: 1).
Table 7

The experimental results for the four items in Table 7 (confirmation of poor mixing, confirmation of mixed state, measurement of dissolved oxygen, measurement of foaming amount) are summarized in Table 8 below. The poorly mixed portion and the mixed state are indexes indicating the stirring performance, and the smaller the poorly mixed portion and the smaller the particle size of the preparation and the smaller the amount of precipitation, the better the stirring performance. Moreover, since the amount of dissolved oxygen increases due to foaming, the amount of dissolved oxygen is an index indicating the degree of foaming.
Table 8

表１０

表１１

Of the four items, the results regarding the mixed state are shown in Table 9, and the results when the stirring blade is completely immersed in the liquid (full amount) in the measurement of the dissolved oxygen concentration are shown in Table 10. Table 11 shows the results when the upper end of the above and the liquid level are approximately equal (stirring blade surface water level). The "precipitation amount" in Table 9 is a value obtained by dividing the amount of precipitation obtained by the method shown in Table 7 by the total amount of the preparation to be centrifuged × 100 (%).
Table 9

Table 10

Table 11

According to the evaluation results shown in Tables 8 and 9, Comparative Example 1 was significantly inferior to the control in both the poorly mixed portion and the mixed state.
On the other hand, in Example 1, the poorly mixed portion, the particle size of the preparation, and the amount of precipitation were the same as those of the control. Therefore, it was confirmed that Example 1 had the same stirring performance as the control.

In addition, in the measurement of the dissolved oxygen concentration, in the case of "full amount" (Table 10), the dissolved oxygen concentration in the control was 4.59 mg / L after 30 minutes, whereas in Example 1, it was 2.18 mg / L. In Example 1, the dissolved oxygen concentration was reduced by 50% or more as compared with the control. Also, in the case of "stirring blade surface water level" (Table 11), the dissolved oxygen concentration was 4.08 mg / L in Example 1 against the oxygen dissolved concentration of 7.23 mg / L in the control after 30 minutes. Significant improvement was seen. Further, as shown in Table 8, it was confirmed that the amount of foaming in Example 1 was very small as compared with the control in both "full amount" and "water level on the stirring blade surface".
From this, if the configuration described with reference to FIGS. 1 to 4 is combined with the non-constant velocity rotational motion, the stirring performance is high and the effect of suppressing the generation of bubbles is controlled (stirring according to the prior art). It was confirmed that the result exceeded that of the tank).

[Experimental Example 4]
In Experimental Example 4, in order to examine the size of the comb-shaped stirring blade, the stirring efficiency (stirring performance) and the amount of bubbles generated (foaming) were measured.
Table 12 shows the conditions of the two types of stirring blades (Example 2 and Comparative Example 2) used in Experimental Example 4.
Table 12

In Table 12, the wording "comb (50%)" in the "stirring blade shape" line means that the diametrical dimension of the comb-shaped stirring blade is 50% of the inner diameter of the stirring tank. The wording "mold (90%)" means that the diametrical dimension of the comb-shaped stirring blade is 90% of the inner diameter of the stirring tank.
The comb-shaped stirring blade of Example 2 is the same as that of Example 1. Further, the comb-shaped stirring blade (“comb-shaped (90%)”) of Comparative Example 2 has four combs, and the lower end portion of the comb-shaped stirring blade is parallel to the horizontal plane on the bottom surface of the stirring tank.
In Table 12, in "Example 2" and "Comparative Example 2", the required power for stirring is the same, and the ratio of the rotation speed at low speed to the rotation speed at high speed of non-constant velocity stirring is 1: 1.75. Yes, the non-constant velocity stirring device is the same as in Example 1. Further, as for the stirring rotation speed in Table 12, the rotation speeds of the gears rotating at a constant speed among the gears used in the non-constant speed stirring device are described in the same manner as in Example 1.
Others are the same as those described in Experimental Examples 1 to 3.

表１４

In Experimental Example 4, the so-called "iodine hypo method" (see Table 7) was performed for the stirring performance, and for confirmation of foaming, water was injected into the stirring tank and the stirring blade was completely immersed in the liquid. With respect to (full amount), dissolved oxygen was measured with continuous stirring for 30 minutes.
The comparison result of the stirring performance is shown in Table 13 below, and the comparison result regarding foaming is shown in Table 14 below.
Table 13

Table 14

According to Table 13, it was confirmed that in Example 2 as compared with Comparative Example 2, the mixing was completed in a short time when the required power for stirring was kept constant. From this, it was found that the diameter direction dimension (width dimension) of the comb-shaped stirring blade is preferably 50% or less of the inner diameter of the stirring tank from the viewpoint of stirring efficiency.
There was no significant difference between the samples in terms of dissolved oxygen concentration (results in Table 14).

The experimental results shown in Table 14 are for the case where the required power for stirring is the same, and in that case, as described above, no significant difference in the dissolved oxygen concentration was observed between the samples.
Therefore, the dissolved oxygen concentration was measured again with the rotation speeds of Example 2 and Comparative Example 2 kept constant (73 rpm). The results are shown in Table 15.
Table 15

As a result of re-measurement at a constant rotation speed (73 rpm), it was confirmed that the dissolved oxygen concentration in Comparative Example 2 increased as compared with Example 2, although the mixing property of Comparative Example 2 was improved. ..
From the above, it was found from Experimental Example 4 that the diameter direction dimension (width dimension) of the comb-shaped stirring blade is preferably 50% or less of the inner diameter of the stirring tank from the viewpoint of stirring efficiency and dissolved oxygen concentration (foaming suppression).

It is added that the illustrated embodiment is merely an example and is not a description intended to limit the technical scope of the present invention.

1 ... Stirring tank 2 ... Stirring blade 3 ... Rotor blade rotation mechanism 11 ... Side wall 12 ... Bottom 13 ... Top mirror 22 ... Opening 24 ... Vertical rail

Claims (8)

In a stirring tank and a stirring device having stirring blades,
The axis of rotation of the stirring blade extends to the central axis of the stirring tank.
The entire stirring blade is flat and has an opening extending in the vertical direction, the radial outer edge of the stirring blade extends in the vertical direction, and the radial dimension of the stirring blade is It is 60% or less of the inner diameter of the stirring tank,
The bottom of the stirring tank is conical and
A stirring device characterized by having a rotating mechanism that rotates a rotating shaft of a stirring blade at a non-constant speed that repeats low speed and high speed at regular intervals. The stirring device according to claim 1, wherein the ratio of the rotation speeds of the stirring blades at low speed and high speed is 1: 1.5 to 1: 4. The stirring device according to any one of claims 1 and 2, wherein the bottom surface of the stirring tank has a conical shape, and the central axis of the conical shape is inclined with respect to the central axis of the stirring tank. The stirring device according to any one of claims 1 to 3, wherein the diameter direction dimension of the stirring blade is 40 to 60% of the inner diameter of the stirring tank. The stirring device according to any one of claims 1 to 4, wherein the vertical dimension of the stirring blade is 100 to 300% of the radial dimension. The stirring device according to any one of claims 1 to 5, wherein the area of the opening is 20 to 50% with respect to the stirring blade. The stirring device according to any one of claims 1 to 6, wherein 4 to 6 regions other than the opening in the stirring blade and extending continuously in the vertical direction are provided. The stirring device according to any one of claims 3 to 7, wherein the lower end portion of the stirring blade extends parallel to the region having the largest inclination angle with respect to the horizontal plane on the bottom surface of the stirring tank.

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