JP3224498B2 - Stirrer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stirrer, and more particularly to a stirrer capable of rapidly and uniformly stirring and mixing a fluid having a wide viscosity range from low viscosity to high viscosity.

[0002]

2. Description of the Related Art A stirrer equipped with a stirring tank, a rotating shaft rotatably supported in the stirring tank, and a stirring blade rotatably fixed to the rotating shaft in the stirring tank has conventionally been used in the chemical industry. Widely used in the field.

For example, Japanese Patent Application Laid-Open No. Hei 5-49890 discloses that a rotating shaft is vertically provided at a central portion in a vertical cylindrical stirring tank, and a plurality of paddle blades are mounted on the rotating shaft in upper and lower stages. The lower paddle blades are arranged close to the bottom of the stirring tank, and the upper paddle blades are positioned in front of the lower paddle blades vertically adjacent to each other at an intersection angle of less than 90 degrees in the rotation direction. A stirring device is disclosed. In this stirrer, one large circulating flow over the entire stirring tank is formed by arranging the upper and lower paddle blades at an intersection angle of less than 90 degrees, so that stirring operation conditions from the transition flow to the laminar flow region are performed. This has the advantage that the stirring efficiency of the fluid in can be greatly improved. In addition, 1-37-1717
In JP-A-3, a stirring shaft rotatable from the outside of the tank is provided at the center of the stirring tank, and the bottom paddle disposed at the bottom of the tank is slid on the bottom wall of the stirring tank at the lower end thereof. Attach and attach a lattice blade composed of an arm portion and a strip extending in a direction perpendicular to the arm portion above the bottom paddle of the stirring shaft, and a plurality of blades along the axial direction from the bottom to the top on the side wall surface of the stirring tank. A stirrer in which baffles are arranged at intervals is disclosed. In this stirrer, the liquid at the bottom of the tank is discharged in the radial direction by the bottom paddle and collides with the side wall of the tank, and the liquid in the tank is restrained from moving in the tank by the baffle plate and is moved upward to the top of the tank. The liquid descending in the tank is sheared and fragmented by the arm portion and the strip, and the fragmented liquid is entrained and mixed in a fine vortex generated behind the arm portion and the strip. Therefore, since the whole liquid in the stirring tank can be mixed by mixing the divided liquids, the power required for stirring can be small, and the mixing performance at the time of low-speed rotation stirring (at the time of low power required) can be improved. Have the advantages that can be. Also,
Japanese Patent Application Laid-Open No. 6-198155 discloses that a rotating stirring shaft arranged in a vertical direction is installed in a stirring tank, and a vertical flat blade and a vertical flat blade arranged in parallel with the axis of the stirring shaft are provided. A plurality of blade groups consisting of a plurality of inclined flat blades having an inclination angle with respect to the axis of the stirring shaft arranged so as to generate a descending flow are arranged vertically and attached to the stirring shaft, and the adjacent A stirrer in which the directions of the vertical flat blade and the inclined flat blade of the blade group are shifted from each other is disclosed. In this stirrer, a vertical plate impeller generates an ascending flow in an object near the inner wall surface of the stirring tank, and an inclined flat plate blade causes a descending flow in an object near the center of the stirring tank to generate a descending flow. Since the flow is formed over the entire inner region, there is an advantage that two or more kinds of liquids having different viscosities can be mixed quickly and efficiently.

Further, a stirring tank 1, a rotating shaft 2 rotatably supported in the stirring tank 1, and a rotating shaft 2 rotatably fixed in the stirring tank 1 and inclined with respect to the rotating shaft 2. It has a pair of semi-elliptical upper blades 3 extending radially and vertically, and a lower blade 4 disposed close to the upper blades 3 and extending downward and radially from the rotary shaft 2 to near the bottom surface of the stirring tank 1. FIGS. 14 and 15 show a stirring device provided with the stirring blade 5 and a baffle plate 6 provided between the inner wall of the stirring tank 1 and the stirring blade 5. 14 and 15, since a large vertical circulating flow can be generated by the semi-elliptical upper wings 3, there is an advantage that the liquid in the stirring tank 1 can be stirred and mixed quickly and efficiently. . For example, as shown in FIG. 16, a four-pitch paddle blade 16a having two upper and lower sets of four paddle blades 16a as shown in FIG. The stirring blades of the stirring device used for stirring and mixing the liquid in the region include:
For example, as shown in FIG.
A helical ribbon blade 17 provided with a pair is used.

[0005]

In the conventional stirring apparatus, when the liquid in the stirring tank has a medium viscosity or more, the circulating flow in the vertical direction is weakened. However, there is a disadvantage that the liquid in the whole stirring tank cannot be uniformly stirred and mixed. FIG.
As the viscosity of the liquid in the stirring tank increases in the stirring device shown in FIG. 1, the liquid flows radially outward at the lower end 3a of the semi-elliptical upper blade 3 as shown in FIG.
The flow of the liquid inside the lower wing 4 is weakened. FIG.
In the stirrer shown in (1), the inside of the stirring tank 1 is filled with an aqueous solution of starch syrup having a viscosity of 74P and the aqueous solution has a particle diameter of 4.4 mm
Tracer particles (PMMA particles)
19 (A) and 19 (B) show the flow trajectory and the reached depth of the tracer particles in the stirring tank 1 in the case where the rotation speed was set to 90 rpm, respectively. That is, the bold line in FIG. 19A shows the locus of the tracer particles flowing most frequently, and FIG.
Shows the percentage of the frequency of tracer particles present at each of the division points when the liquid surface to the bottom of the tank is divided into 10 parts in the depth direction. From FIGS. 19A and 19B, it can be seen that the frequency of tracer particles in the stirring tank 1 reaching the tank bottom is low. For this reason, there is a disadvantage that the circulating flow generated in the stirring tank 1 does not reach the bottom of the tank and the liquid near the bottom of the stirring tank 1 cannot be sufficiently stirred.

[0006] The mixing performance of the stirrer can be evaluated by the time required for decolorization using a decolorization reaction of, for example, an iodine-hypo aqueous solution. Lines B and C in the logarithmic graph of FIG. 7 are respectively the stirring and mixing of the iodine-hypo aqueous solution in the stirring device having the four-pitch paddle blades 16 shown in FIG. 16 and the stirring device having the helical ribbon blades 17 shown in FIG. shows the relationship between the Reynolds number Re and the dimensionless mixing time number N _TM frames that have undergone decolorization reaction with. Here, the Reynolds number Re indicates that the low viscosity of the liquid stirring tank 1 as their number is large, the number N _TM dimensionless mixing time is iodo the rotational speed of the stirring blade - required for decolorization of hypo solution time, That is, a value obtained by multiplying the bleaching time is shown. As shown in line B of Figure 7, in the case of four pitched paddle blades 16 shown in FIG. 16, the Reynolds number Re bleaching time number N _TM dimensionless mixing time is small is short of 100 or more relatively low viscosity region Therefore, if Re is less than 100, the dimensionless mixing time _NTM increases rapidly and the mixing performance decreases. Further, as shown by the line C in FIG. 7, in the case of the helical ribbon blade 17 shown in FIG. 17, the Reynolds number Re is 10
In a relatively high viscosity region of 0 or less, the dimensionless mixing time N
_TM change is relatively small and mixing performance is excellent, but Re is 1
In the low-viscosity region of 00 or more, the mixing performance is lower than that of the four-pitch paddle blade 16 in FIG. Therefore, a low-viscosity blade such as the four-pitch paddle blade 16 shown in FIG. 16 and a high-viscosity blade such as the helical ribbon blade 17 shown in FIG. 17 must be used in accordance with the viscosity of the liquid. Therefore,
The conventional stirrer has a disadvantage that one kind of stirrer cannot quickly and efficiently stir and mix when the viscosity of a liquid such as a polycondensation reaction changes in a wide range.

Accordingly, an object of the present invention is to provide a stirrer that can rapidly and uniformly stir and mix fluids in a wide viscosity range from low viscosity to high viscosity.

[0008]

A stirrer according to the present invention comprises a stirrer and an upper blade fixed to a stirrer rotating shaft (hereinafter simply referred to as a rotating shaft) rotatably supported in the stirrer. A lower blade and a stirring blade. The two lobes of the first upper wing of the upper wing are fixed to the rotating shaft while being inclined at a predetermined upward angle in the direction of rotation of the rotating shaft.
At a predetermined lower portion of the first upper wing, two leaves of the second upper wing are fixed to the rotating shaft while being inclined at a predetermined downward angle toward the rotating direction of the rotating shaft. Also, the upper end of the lower wing is close to the lower end of the second upper wing, the lower end of the lower wing is close to the inner bottom surface of the stirring tank, and the lower wing has an end facing the inner surface of the stirring tank. To the vicinity of the inner surface of the stirring tank. Further, a pair of inclined wings are formed on the upper and lower portions of the rotating shaft so as to sandwich the two leaves of the first and second upper wings from both sides toward the rotating shaft. A pair of inclined step blades intersecting with each other is formed by sandwiching the two blades of the inclined blade intersecting the upper and lower portions from both sides of the rotation shaft. Furthermore, the lower side of the first upper wing and the upper side of the second upper wing forming the stepped portion of the inclined stepped blade have portions overlapping each other in the direction of the stirring rotation axis. The outer peripheral end from the stirring rotation axis of the pair of inclined step blades toward the inner wall of the stirring tank is a position where the inclined step blades can rotate in the stirring tank. In such a stirring device according to the present invention, the first upper wing forming the inclined step wing moves the liquid in the stirring tank downward, and is provided at a predetermined lower portion of the first upper wing. The second upper wing is formed as a divided wing having a step with respect to the first upper wing. Therefore, the step portion serves as an inlet for sucking the liquid, and the first
The upper wing moves the liquid above the stirring tank to the bottom of the tank by the suction force generated in the overlapping part with the upper wing, and the lower wing moves the liquid at the bottom of the stirring tank to the inside of the stirring tank. The liquid is moved upward along the inner wall of the stirring tank. Also, the blade width toward the upper and lower ends of the inclined step blade is gradually reduced from the blade width of the overlapping portion, and the upper and lower ends of the inclined step blade are as close as possible to the inner surface of the stirring tank. The shape of the inclined stepped wing may be used. The first upper wing and the second upper wing each include a pair of quarter-elliptical flat plates arranged symmetrically with respect to the rotation axis, and the first and second upper wings have a semi-elliptical shape. The upper wing is formed as an inclined step wing. In addition, with respect to the second upper wing provided at a predetermined lower portion with respect to the first upper wing, a horizontal plane distance d between the upper end of the first upper wing and the lower end of the second upper wing and the second The range of the ratio of the first and second upper wings to the interval C in the rotation axis direction is desirably 0.05 ≦ C / d ≦ 0.6, and the first upper wing and the downward inclination that are inclined upward in the rotation direction of the rotation axis. The range of the predetermined inclination angle θ with the inclined second upper wing is 30 ° ≦ θ ≦
60 ° is desirable. In addition, a baffle plate is provided in a gap with the inner wall of the agitation tank, and the baffle plate is provided near an end of the agitation blade in the inner surface direction of the agitation tank. Providing this baffle plate makes it easier for the liquid to move upward along the inner wall of the stirring tank as a well-known effect. Further, a portion overlapping the upper side of the lower wing in the axial direction may be provided at the bottom of the second upper wing.

When the stirring blade comprising the first and second upper blades and the lower blade is rotated, the liquid in the stirring tank is moved downward by the first upper blade, and the liquid moved downward is further removed by the first upper blade. 2 is moved to the bottom of the tank by the upper wing. At this time, the first
The positive pressure is generated on the lower surface side of the upper wing and the second upper wing, and the negative pressure is generated on the upper surface side, so that the lower side of the first upper wing and the upper side of the second upper wing overlap each other. A suction force is generated, and the liquid in the stirring tank moved downward by the first upper blade is reliably drawn into the tank bottom by the second upper blade through the overlapping portion. The liquid drawn into the tank bottom by the second upper blade is moved radially outward by the lower blade, and this liquid is further moved upward along the inner wall of the stirring tank. This generates a relatively strong and large circulating flow of the liquid in the stirring tank reaching the bottom of the tank, so that the liquid in a wide viscosity range from low viscosity to high viscosity can be stirred and mixed quickly and efficiently. Further, since the liquid in the stirring tank can be reliably drawn into the tank bottom by the suction force generated in the overlapping portion between the first upper blade and the second upper blade, the entire liquid in the stirring tank can be promptly and rapidly discharged. Stir and mix uniformly. When each of the first and second upper wings is formed of a pair of quarter-elliptical flat plates to form a pair of first and second upper wings to form a pair of semi-elliptical upper wings, the wings may be arranged in a radial direction. The liquid in the stirring tank can be stirred to every corner because it can be stretched widely to one cup. Furthermore, when a baffle plate is provided between the inner wall of the stirring tank and the stirring blade, it is possible to prevent the flow of the liquid along the rotation direction of the stirring blade and change it into an upward flow, thereby promoting the circulation flow in the tank. it can.

A preferred embodiment of the stirring device according to the present invention will be described below with reference to FIGS. However, in these drawings, substantially the same parts as those in FIGS. 14 to 19 are denoted by the same reference numerals, and description thereof will be omitted. The stirrer according to the present invention is, as shown in FIG. 1, replaced with the two-leaf inclined blade 3 of the stirring blade 5 in the conventional stirrer shown in FIG.
It has a stirring blade 10 provided with upper blades 7 and 8 including two leaves of a first upper blade 7 and two leaves of a second upper blade 8 inclined with respect to the rotation axis 2. The two lobes of the first upper wing 7 of the upper wing are fixed to the rotating shaft 2 while being inclined at a predetermined upward angle θ in the rotation direction of the rotating shaft 2 of the stirring tank 1. The two leaves of the second upper wing 8 are provided below the predetermined interval C between the two leaves of the first upper wing 7 at a predetermined downward angle θ in the rotation direction of the rotating shaft 2 of the stirring tank 1. It is inclined and fixed to the rotating shaft 2 (FIG. 1). These two leaves of the first upper blade 7 of the two leaves and the second upper blade 8 of the two leaves are sandwiched from both sides toward the rotation shaft 2 so that the upper and lower parts are mutually positioned with respect to the stirring shaft 2. , Each forming a pair of inclined step wings 7 and 8 (FIGS. 1 and 2).
In addition, the first upper wing 7 of these four-leaf upper wings 7 and 8
As described above, the two leaves of the first upper wing 7 and the second upper wing 8 are sandwiched from both sides of the rotary shaft 2 so as to form a step that is inclined because they are located above and below each other. The second upper blade 8 forms a pair of inclined step blades [7, 8] that intersect each other and are divided at the step section (FIGS. 1, 2, and 12). Such an inclined step wing [7, 8]
The lower side 7a of the first upper wing 7 and the upper side 8a of the second upper wing 8, which are divided portions, form a portion overlapping each other in the direction of the stirring rotation axis (FIGS. 1, 2 and 3). (Fig. 6). Moreover, the outer peripheral end of the pair of inclined step blades [7, 8] from the stirring rotation axis toward the inner wall of the stirring tank is located at a position where the inclined step blade can rotate in the stirring tank (FIG. 1, FIG. 1). 3 and 5). Further, the lower end of the lower blade 9 provided close to the lower end 8b of the inclined step blade [7, 8] has the vicinity of the bottom surface of the stirring tank, and the radius of the stirring tank 1 of the lower blade 9 is provided. The end in the direction extends to the vicinity of the inner surface of the stirring tank 1 (FIG. 1). In the present invention, the horizontal distance d between the upper end 7b of the first upper wing 7 and the lower end 8b of the second upper wing 8 and the vertical distance C between the first and second upper wings 7, 8 are determined. Of the ratio (C / d) is preferably 0.05 ≦ C / d ≦ 0.6, and the inclination angle θ of the first and second upper wings 7, 8 with respect to the horizontal plane (the above-mentioned predetermined upward and Is preferably 30 ° ≦ θ ≦ 60 °. In the example shown in FIG. 1, C / d = 0.13, θ =
45 °.

As shown in FIG. 2, the first upper wing 7 and the second upper wing 8 are each composed of a pair of quarter-elliptical flat plates 11 arranged symmetrically with respect to the rotation axis 2.
As shown in (1), a pair of first and second upper wings 7 and 8 form a semi-elliptical upper wing. As shown in FIG. 4, the lower wing 9 is composed of a pair of flat plates 12 extending downward and parallel to the rotation axis 2 and symmetrically arranged. Are formed with bent portions 12a each having a receding angle of 45 ° with respect to the rotation direction. Further, an inclined portion 12b is formed at the bottom of the pair of flat plates 12 of the lower blade 9 to avoid contact with the bottom plate of the stirring tank 1.
As shown in FIG. 5, three baffle plates 6 are provided in the circumferential direction of the stirring tank 1 and are close to the radial end 10a of the stirring blade 10. Other configurations are the same as those of the stirring device shown in FIG.

By rotating the rotating shaft 2 in the direction of the arrow, the first and second upper blades 7 and 8 and the lower blade 9 rotate, and the first upper blade 7 moves the liquid in the stirring tank 1 downward. The second upper blade 8 moves the liquid moved downward by the first upper blade 7 further to the bottom of the stirring tank 1. At this time, the lower side 7a of the first upper wing 7 and the upper side of the second upper wing 8 are formed by the pressure applied to the surface 7c of the first upper wing 7 and the negative pressure on the back surface 8c of the second upper wing 8. A suction force is generated in the overlapping portion with the portion 8a. For this reason, as shown in FIG. 6, the liquid in the stirring tank 1 moved downward by the first upper blade 7 is drawn into the overlapping portion and is pushed out further downward, and is further pushed downward by the second upper blade 8. Is securely pulled into the bottom of the The liquid drawn into the bottom of the stirring tank 1 is moved radially outward by the lower blade 9, and the baffle 6 prevents the flow of the liquid along the rotation direction of the stirring blade 10. Thereby, the stirring tank 1
The liquid inside is moved upward along the inner wall of the stirring tank 1.
At this time, the amount by which the liquid is moved downward by the first and second upper wings 7 and 8 and the amount by which the liquid is moved radially outward by the lower wing 9 are balanced, so that the flow of the liquid is continued and the stirring is continued. Since the area of the blade 10 is relatively large and the gap between the radial end 10a of the stirring blade 10 and the baffle plate 6 is extremely narrow,
A large circulation flow is generated in the liquid in the stirring tank 1 which is relatively strong and reaches the bottom of the tank. In a stirred apparatus of FIG. 1-iodo - shows the relationship between the Reynolds number Re and the dimensionless mixing time number N _TM frames that have undergone decolorization reaction by stirring and mixing the hypo solution in line A logarithmic graph of FIG. According to FIG.
The case of the stirrer of FIG. 1 (line A) is the case of the stirrer with four pitched paddle blades shown in FIG. 16 (line B) and the case of the stirrer with helical ribbon blades shown in FIG. 17 (line C). ), The number of non-dimensional mixing times _NTM is small over a wide range of viscosities, indicating that the decolorization time is short. Therefore, the liquid in the stirring tank 1 can be rapidly and efficiently stirred and mixed over a wide viscosity range from low viscosity to high viscosity. Further, since the liquid in the stirring tank 1 can be reliably drawn to the bottom by the suction force generated in the overlapping portion of the first upper blade 7 and the second upper blade 8, the liquid in the entire stirring tank 1 can be removed. Stir and mix quickly and uniformly. Further, in this example, since a pair of first and second upper wings 7 and 8 form a pair of semi-elliptical upper wings, the wings can be extended widely to the full extent in the radial direction, and the clearance with the baffle plate 6 can be reduced. Then, the liquid in the tank can be thoroughly stirred. Further, since the bent portions 12a are formed at both ends of the pair of flat plates 12 of the lower blade 9, the liquid at the bottom of the stirring tank 1 can be quickly moved radially outward. Also, since the inclined portion 12b is formed on the bottom side of the pair of flat plates 12 of the lower wing 9,
The blade can be extended widely downward, and the clearance between the stirring tank 1 and the bottom plate can be reduced to stir the liquid in the tank to every corner.

[0013]

EXAMPLE In the stirring apparatus shown in FIG.
In the same manner as the stirring device shown in FIG. 1, the inside of the stirring tank 1 is filled with an aqueous solution of starch syrup having a viscosity of 74P, and tracer particles (PMMA particles) having a particle diameter of 4.4 mm are mixed into the aqueous solution.
FIG. 8 (A) and FIG. 8 (A) show the flow trajectory and the reaching depth of the tracer particles in the stirring tank 1 when the operation was performed at a rotation speed of 90 rpm.
(B) shows each. Here, comparing FIGS. 19 (A) and (B) with FIGS. 8 (A) and (B), the frequency of tracer particles in the aqueous solution in the stirrer shown in FIG. It can be seen that the circulating flow generated in the liquid in the stirring tank 1 reaches the bottom of the tank, and the liquid in the entire stirring tank 1 can be rapidly and uniformly stirred and mixed. The dimensions of each part of the stirring device shown in FIG. 1 are set so as to have a relationship as shown in FIG.

Comparative Example 1 In the stirring apparatus of FIG. 1, the inclination angle θ of the first and second upper blades 7 and 8 was fixed at 45 ° and the value of C / d was 0.05, 0.13, Table 1 shows the decolorization time when the Reynolds number Re was 9 when the iodine-hypo aqueous solution was decolorized by stirring and mixing at 0.6.
Shown in However, in this comparative example, the comparison was performed with the capacity of the stirring tank 1 being 10 liters and the rotation speed of the stirring blade 10 being 84 rpm. The aqueous solution of iodine-hypopoise is composed of an aqueous solution of starch syrup having a viscosity of 50 P, containing 1.2 parts of iodine and 1.2 parts of hypo.

[Table 1] As shown in Table 1, the upper end 7b of the first upper wing 7 and the second upper wing 7
Horizontal distance d between the lower end 8b of the upper wing 8 and the first and second
When the ratio C / d of the upper wings 7 and 8 to the vertical interval C is 0.13, the decolorization time is shortest, that is, the time required for decolorization is short, so the value of C / d is 0.13. It can be seen that the closer the mixture, the better the mixing efficiency. In this case, the amount by which the aqueous solution is moved downward by the first and second upper wings 7 and 8 and the amount by which the aqueous solution is moved radially outward by the lower wing 9 are balanced, so that the flow of the aqueous solution is continued. It is considered that a circulating flow that flows through the entire inside is formed. When the value of C / d is 0.05, the amount of the aqueous solution sucked into the overlapping portion of the first and second upper wings 7 and 8 decreases, so that the vicinity of the lower end 8b of the second upper wing 8 is reduced. A flow of the aqueous solution occurs radially outward.
For this reason, it is difficult for the aqueous solution to move to the bottom of the tank, and the mixing efficiency is reduced. Therefore, the decolorization time of the iodine-hypo aqueous solution is longer than in the case of C / d = 0.13. When the value of C / d is 0.6, the first and second
Since the vertical spacing between the upper wings 7 and 8 of the
The suction force generated in the overlapping portion of the second upper wing 7 and the second upper wing 8 is weakened, and the force of pushing the aqueous solution to the bottom of the tank by the first and second upper wings 7 and 8 is reduced. For this reason, the flow velocity of the circulating flow generated in the tank becomes slow, so that the average circulation time for circulating the aqueous solution in the tank becomes long, and the mixing efficiency is reduced. Therefore, also in this case, C / d = 0.13
The decolorization time of the iodine-hypo aqueous solution is longer than in the case of (1). Accordingly, the horizontal distance d between the upper end 7b of the first upper wing 7 and the lower end 8b of the second upper wing 8 from Comparative Example 1 described above.
It is desirable to set the value of the ratio C / d between the vertical distance C between the first and second upper wings 7 and 8 in the range of 0.05 ≦ C / d ≦ 0.6. It can be seen that it is best to set the value of / d to 0.13.

Comparative Example 2 Next, in the stirring device of FIG. 1, the value of C / d was 0.13.
When the decolorization reaction of the iodine-hypo aqueous solution is carried out by stirring and mixing with the inclination angles θ of the first and second upper wings 7 and 8 being 30 °, 45 ° and 60 °, the Reynolds number Re is 9 Table 2 shows the bleaching time. However, in this comparative example, the capacity of the stirring tank 1 was 10 liters,
The comparison was made with the rotation speed of 0 set to 84 rpm. Also,
The aqueous iodine-hypo aqueous solution is composed of an aqueous solution of starch syrup having a viscosity of 50P and a ratio of iodide to hypo to 1.2.

[Table 2] As shown in Table 2, the decolorization time is the shortest when the inclination angle θ of the first and second upper wings 7 and 8 is 45 °, so that the closer the inclination angle θ is to 45 °, the better the circulation in the tank. It can be seen that it can be obtained. Inclination angle θ of first and second upper wings 7, 8
When the angle is 30 °, the height of the stirring blade cannot be made sufficiently high with respect to the height from the tank bottom to the liquid level, so that the aqueous solution near the liquid level is not sufficiently stirred and tends to be stagnant. Further, in the balance of the liquid discharge amount between the first and second upper wings 7, 8 and the lower wing 9, the first and second upper wings 7, 8
Is smaller than the upward liquid discharge amount of the lower blade 9, the circulation flow in the stirring tank 1 is divided into upper and lower parts, and smooth circulation in the tank cannot be obtained. Therefore, θ = 4
The decolorization time of the iodine-hypo aqueous solution is longer than that at 5 °. When the inclination angle θ of the first and second upper wings 7 and 8 is 60 °, the first and second upper wings 7 and 8
The amount of liquid discharged outward in the radial direction increases as compared with the amount of liquid discharged downward, and the amount of pushing the aqueous solution to the bottom of the tank decreases, so that the circulating flow in the stirring tank 1 is divided vertically and smoothly. In-tank circulation cannot be obtained. Therefore, also in this case, the decolorization time of the iodine-hypo aqueous solution is longer than in the case of θ = 45 °. Therefore, the inclination angle θ of the first and second upper wings 7 and 8 with respect to the horizontal plane is 3
It can be seen that it is desirable to set the range of 0 ° ≦ θ ≦ 60 °, and it is best to set θ to 45 °.

Comparative Example 3 Further, in a conventional stirring device having an anchor type anchor blade near the bottom of the tank and the stirring device shown in FIG. 1, hypo was added to an aqueous solution of starch syrup having a viscosity of 50 P containing iodine. FIGS. 10 and 11 show the progress of decolorization of the aqueous solution in the case of performing the decolorization reaction by stirring and mixing, respectively. However, the rotation speed of the anchor blade in the conventional stirring device is 66 rpm, the Reynolds number Re is 11.4, and the rotation speed of the stirring blade 10 in the stirring device of FIG.
m and Reynolds number Re are 8.9. The power consumption per unit volume of both is 1.0 kw / m ³ , and the iodine / hypo content ratio in the aqueous starch syrup solution is 1: 1.2. According to FIGS. 10 and 11, after 300 seconds, the stirring device of FIG.
In addition, since the second stirring blades 7, 8 and the lower blade 9 are clearly shown, it can be seen that the decolorization is completed over substantially the entire inside of the tank. Incidentally, although not shown in FIG. 10, the time required to complete the decolorization in the entire tank in the conventional stirring device is 400 seconds later. Therefore, it can be seen that the aqueous solution in the entire stirring tank 1 can be rapidly and uniformly stirred and mixed in the stirring device of FIG. 1 as compared with the conventional stirring device.

The embodiment of the present invention is not limited to the above embodiment, but can be modified. For example, in the above-described embodiment, an example is shown in which a pair of first and second upper wings 7 and 8 composed of a pair of quarter-elliptical flat plates 11 form a semi-elliptical upper wing. The shape of the second upper wings 7, 8 is not limited to a semi-elliptical shape, but can be various shapes. For example, as shown in FIGS. 12 and 13, the first and second upper wings 14 and 15 are configured by a pair of trapezoidal flat plates 13 each having an inclined portion 13 a on one side, and each upper wing 14 and 15 is half. A hexagonal upper wing may be formed. In addition, the lower end of the second upper wing 8 may include a portion that overlaps the upper side of the lower wing 9 in the axial direction.

[0018]

As described above, according to the present invention, a fluid having a wide viscosity range from low viscosity to high viscosity can be rapidly and uniformly stirred and mixed. Even in the case of a change, it can be used without replacing the stirring blade, and the stirring efficiency can be improved to obtain a high quality polymer. Also, when a baffle plate is provided between the inner wall of the stirring tank and the stirring blade, the effect of preventing the flow of the liquid along the rotation direction of the stirring blade and changing the flow to an upward flow, thereby promoting the circulation flow in the tank is obtained. can get. Also, in the case where the cooling coil is installed in a vertical baffle shape or a helical coil shape in the stirring tank for the high heat generation polymerization, the same effect as when the baffle plate is provided by the cooling coil is obtained, and the circulation in the tank is achieved. The advantage is that flow is facilitated.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a preferred embodiment of a stirring device according to the present invention.

FIG. 2 is a perspective view showing the shapes of first and second upper blades used in the stirring device of FIG.

FIG. 3 is a front sectional view of the stirring device of FIG. 1;

FIG. 4 is a perspective view showing a shape of a lower wing used in the stirring device of FIG. 1;

FIG. 5 is a plan sectional view of the stirring device of FIG. 1;

FIG. 6 is a side sectional view showing a flow of a liquid in first and second upper blades of the stirring device of FIG. 1;

Figure 7 is a graph showing a relationship between the Reynolds number Re and the dimensionless mixing time number N _TM during bleaching reaction of various stirring device

8 is a partial front cross-sectional view showing a flow trajectory of tracer particles in a liquid of the stirring device of FIG. 1 and a graph showing the frequency of existence of tracer particles at each division of a stirring tank.

FIG. 9 is a three-sectional view showing a relationship between dimensions of each part of the stirrer of FIG. 1;

FIG. 10 is a diagram showing a decolorization process of an iodine-hypomixture in a stirring device having an anchor blade.

FIG. 11 is a diagram showing a decolorization process of an iodine-hypomixture in the stirring device of FIG. 1;

FIG. 12 is a perspective view showing shapes of first and second upper wings according to another embodiment of the present invention.

FIG. 13 is a front view and a plan view of the first and second upper wings of FIG. 12;

FIG. 14 is a side sectional view showing a conventional example of a stirring device.

15 is a perspective view and a plan view showing the shape of an upper wing used in the stirring device of FIG.

FIG. 16 is a perspective view showing the shape of a four-pitch paddle wing.

FIG. 17 is a perspective view showing the shape of a helical ribbon wing.

FIG. 18 is a side sectional view showing the flow of liquid in the upper wing of the stirring device of FIG.

19 is a partial front cross-sectional view showing a flow trajectory of tracer particles in a liquid of the stirring device of FIG. 14, and a graph showing the frequency of tracer particles at each division of the stirring tank.

[Explanation of symbols]

1. . . Stirring tank; . . Rotation axis; . . Upper wing, 3
a. . . Lower end, 4. . . 4. lower wing; . . Stirring blades,
6. . . Baffle board, 7. . . First upper wing, 7a. . . Lower side, 7b. . . Top, 7c. . . Surface, 8. . . Second upper wing, 8a. . . Upper side, 8b. . . Lower end, 8c. . .
Back, 9. . . Lower wing, 10; . . Stirrer blade, 10
a. . . 10. radial end; . . 11. a pair of quarter-elliptical flat plates; . . A pair of flat plates, 12a. . . Bent part, 1
2b. . . Inclined part

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Michio Jono 3-29-5 Takada, Toshima-ku, Tokyo Inside Soken Chemical Co., Ltd. (56) References JP-A-49-4253 (JP, A) JP-A-5-29 103962 (JP, A) JP-A-4-90839 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01F ^7/ 00-7/32

Claims (8)

(57) [Claims] A stirrer having an upper blade and a lower blade fixed rotatably in a stirring tank and fixed to a rotation shaft for stirring, wherein the upper blade has a two-leaf first blade. An upper wing and two lobes of the second upper wing, wherein the two lobes of the first upper wing are provided to be inclined at a predetermined upward angle in the rotation direction of the stirring rotation axis, and the first upper wing is provided. At a predetermined lower position with respect to the wing, the second upper wing 2
A leaf is provided so as to be inclined at a predetermined downward angle in a rotation direction of the stirring rotation axis, an upper end of the lower wing is close to a lower end of the second upper wing, and a lower end of the lower wing is An end of the lower blade closer to the inner surface of the stirring tank, which is close to the inner surface of the stirring tank, and an inclined blade of each of the first and second upper blades. The two lobes intersect with each other so as to sandwich the stirring rotation axis from both sides, and the two lobes of the sloping wings supported on the upper and lower portions of the two lobes form a pair of inclined step wings that intersect with each other, A lower side of the first upper wing and an upper side of the second upper wing forming a step portion of the inclined step wing have a portion overlapping each other in a stirring rotation axis direction, and the pair of inclined parts The outer peripheral end from the stirring rotation axis of the step blade toward the inner wall of the stirring tank is connected to the inclined step blade in the stirring tank. Stirring device, characterized in that the rolling positions. 2. The stirring device according to claim 1, wherein a lower side of the first upper wing and an upper side of the second upper wing forming a step portion of the inclined step wing are mutually stirred tanks. Having an overlapping portion in the direction of the inner surface and overlapping each other, and further having a wing width toward the upper and lower ends of the inclined step wing gradually narrowing from the wing width of the overlapping section, and A stirrer wherein the upper and lower ends of the blade are as close as possible to the inner surface of the stirring tank. 3. A ratio of C / d relating to installation of the first upper wing and the second upper wing forming the inclined step wing,
The following formula (1), 0.05 ≦ C / d ≦ 0.6 (1) In the formula, d is the horizontal distance between the upper end of the first upper wing and the lower end of the second upper wing. 3. The stirrer according to claim 1, wherein C represents a distance between the first and second upper blades in the direction of the rotation axis of the stirrer. 4. The first of the pair of inclined step wings.
The predetermined upward and downward inclination angles θ relating to the first and second upper wings, respectively, are in the range of 30 ° ≦ θ ≦ 60 °. Stirrer. 5. Each of the four leaves forming the pair of inclined step wings is formed of a quarter-elliptical flat plate, and each of the two leaves forming the pair of inclined step wings forms a semi-elliptical shape. The stirring device according to any one of claims 1 to 4, wherein the stirring device is provided. 6. The method according to claim 1, wherein the lower blade is a pair of flat blades having two leaves, and both ends of the lower blade are provided with a bent portion with a swept angle with respect to the stirring rotation direction. The stirrer according to any one of the preceding claims. 7. The stirrer according to claim 1, wherein a lower end of the inclined step blade and an upper end of the lower blade have a portion overlapping in the direction of the stirring rotation axis. Item 2. The stirring device according to item 1. 8. A baffle plate is provided between an inner surface of a stirring tank and the stirring blade, and the baffle plate is provided near an upper end and a lower end of the inclined step blade. The stirrer according to any one of claims 1 to 7, wherein