JP2010264356A - Stirring method and stirring apparatus for high viscous liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stirring method and a stirring apparatus for preventing roll-up of a liquid to a stirring shaft or the rise of the liquid on the inner wall of a stirring tank when the high viscous liquid is stirred in the stirring tank. <P>SOLUTION: In the method of stirring the liquid 2 to be treated in the stirring tank 3 by rotating a helical ribbon blade 7 with the rotation of the stirring shaft 5 using the stirring apparatus 1 provided with the cylindrical stirring tank 3 in which a liquid 2 to be treated is charged and stored, the stirring shaft 5 arranged inside the stirring tank 3 and the helical ribbon blade 7 attached to the stirring shaft 5, when the stirring shaft 5 is positively rotated, the helical ribbon blade 7 is rotated in the direction scraping up the liquid 2 to be treated and when the viscosity of the liquid 2 to be treated is ≥100 Pa s, the stirring shaft 5 is reversely rotated in the direction that the helical ribbon blade 7 scrapes down the liquid 2 to be treated. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method of stirring the inside of the stirring tank uniformly and preventing the liquid from rising to the inner wall of the stirring tank or rolling up to the stirring shaft when stirring the high viscosity liquid in the stirring tank. .

Conventionally, various stirring devices that have a cylindrical reaction vessel and perform mixing, dispersion, and reaction operations of various liquids to be treated have been proposed. In particular, in the production of adhesives and pressure-sensitive adhesives, products that have been devised in various ways have been proposed from the viewpoint that stirring of a high-viscosity liquid to be treated is essential.
For example, in a high viscosity range of several Pa · s to several thousand Pa · s level, a stirring tank equipped with a stirring shaft disposed in the stirring tank and a helical ribbon blade attached to the stirring shaft is used. Often done. However, in general, when stirring in a high viscosity liquid or non-Newtonian fluid, the phenomenon that the liquid to be treated rises to the inner wall of the stirring tank or the so-called Weisenberg phenomenon is likely to occur on the stirring shaft. The same can be said for stirring with a ribbon blade.
When the above phenomenon occurs in the agitation tank, the liquid to be treated rises on the inner wall of the agitation tank and winds up on the agitation shaft, so that a good agitation / mixing cannot be performed, resulting in an unreacted part. Uneven things will be produced. In addition, since the agitation is not sufficiently performed, the liquid to be treated adheres to and solidifies around the inner wall of the agitation tank, the agitation shaft, and the agitation blade, thereby further reducing the agitation performance.
As said countermeasure, there exists a thing using a baffle plate like patent documents 1-3. In any case, it can be said that the above-mentioned rising phenomenon is prevented by promoting the vertical circulation mixing of the liquid to be treated in the vicinity of the inner wall of the stirring tank.

JP 2002-282667 A JP 2005-46752 A Japanese Patent Laid-Open No. 8-266881

However, when trying to prevent the above-mentioned baffle plate from rising to the inner wall of the stirring tank, the high viscosity liquid / non-Newtonian liquid causes a new rise from the baffle plate or the like as a base point. It is not possible to prevent the rising to the inner wall of the stirring tank. In addition, this is not a technique that takes into consideration the hoisting of the stirring shaft, and the hoisting cannot be prevented.
Furthermore, these baffle plates may cause problems because the gel-like substance generated during the reaction adheres to the baffle plates to inhibit a uniform reaction, and a stagnant portion due to the baffle plates is generated.

  The present invention has been made to solve the above problems, and prevents the liquid from rising up to the inner wall of the stirring tank and from being rolled up to the stirring shaft when the high viscosity liquid is stirred in the stirring tank. The present invention also relates to a method for stirring the inside of the stirring tank uniformly and a stirring device.

  In order to achieve the above object, the stirring method according to claim 1 includes a cylindrical stirring tank into which a liquid to be treated is charged and stored, a stirring shaft disposed in the stirring tank, and a helical ribbon attached to the stirring shaft. In the method of stirring the liquid to be treated in the stirring tank by rotating the helical ribbon blade by rotating the stirring shaft using a stirring device equipped with a blade, and when the stirring shaft is rotated forward, the helical ribbon blade Rotates in the direction to scrape the liquid to be treated, and when the viscosity of the liquid to be treated is 100 Pa · s or more, the helical ribbon blade rotates the stirring shaft in the direction to scrape the liquid to be treated. It is characterized by.

  Further, in the stirring method according to claim 2, the viscosity of the liquid to be treated increases as the stirring progresses, and while the viscosity of the liquid to be treated is less than 100 Pa · s, the stirring shaft is rotated in the forward direction, The rotation of the stirring shaft is switched to the reverse rotation based on the time point when the viscosity of the liquid reaches 100 Pa · s.

  The stirring device according to claim 3 is a cylindrical stirring tank into which a liquid to be treated is charged and stored, a stirring shaft disposed in the stirring tank, a helical ribbon blade attached to the stirring shaft, When the viscosity of the liquid to be processed is less than 100 Pa · s, the helical ribbon blade rotates the stirring shaft in a direction to scoop up the liquid to be processed, and the viscosity of the liquid to be processed Is 100 Pa · s or more, the helical ribbon blade rotates the agitation shaft in the reverse direction so as to scrape the liquid to be treated.

  In the stirring method according to the first aspect, when the viscosity of the liquid to be treated is 100 Pa · s or more, the helical ribbon blade rotates the stirring shaft in the direction of scraping the liquid to be treated. Here, as will be described later, in this high viscosity region, there is no difference in stirring efficiency regardless of whether the stirring shaft is rotated forward or backward. Therefore, without lowering the stirring efficiency, if the stirring shaft is rotated forward in this high viscosity region, the liquid to be treated, which is likely to occur, is prevented from rising up to the inner wall of the stirring tank and rolling up to the stirring shaft. It can be stirred evenly.

  In the agitation method according to claim 2, the viscosity of the liquid to be treated increases as the agitation progresses. However, when the viscosity of the liquid to be treated is less than 100 Pa · s, the agitation shaft is rotated forward. More efficient stirring can be performed by reverse rotation. In addition, since the rotation of the stirring shaft is switched to the reverse rotation based on the time when the viscosity of the liquid to be treated reaches 100 Pa · s, it occurs when the stirring shaft is rotated forward in this high viscosity region without lowering the stirring efficiency. It is possible to prevent the liquid to be treated from easily rising on the inner wall of the stirring tank and from being rolled up to the stirring shaft, and to stir the inside of the stirring tank evenly.

  Further, in the stirring device according to claim 3, when the viscosity of the liquid to be processed stored in the cylindrical stirring tank is less than 100 Pa · s, the stirring shaft is rotated forward, so that the stirring is more efficient than the reverse rotation. It can be performed. When the viscosity of the liquid to be treated is 100 Pa · s or higher, the helical ribbon blade rotates the agitation shaft in the direction to scrape the liquid to be treated, so that the agitation is performed in this high viscosity region without lowering the agitation efficiency. When the shaft is rotated in the forward direction, the liquid to be treated, which is likely to occur when the shaft is rotated forward, can be prevented from rising up to the inner wall of the stirring tank and to the stirring shaft, and the stirring tank can be uniformly stirred.

It is front sectional drawing which represents typically the stirring tank of this embodiment. FIG. 2 is a plan view schematically showing the stirring tank of the present embodiment, and is a view taken along arrow A-A ′ of FIG. 1. It is explanatory drawing which shows the location which traced the density | concentration change in the stirring tank in the case of the simulation for verifying the difference in stirring efficiency by the difference in the rotation direction of the stirring shaft in each viscosity condition. It is a graph which shows the simulation result which concerns on the stirring efficiency at the time of stirring the to-be-processed liquid of viscosity 1Pa * s by normal rotation. It is a graph which shows the simulation result which concerns on the stirring efficiency at the time of stirring the to-be-processed liquid with a viscosity of 1 Pa.s by reverse rotation. It is a graph which shows the simulation result which concerns on the stirring efficiency at the time of stirring the to-be-processed liquid with a viscosity of 10 Pa.s by forward rotation. It is a graph which shows the simulation result which concerns on the stirring efficiency at the time of stirring the to-be-processed liquid of viscosity 10Pa * s by reverse rotation. It is a graph which shows the simulation result which concerns on the stirring efficiency at the time of stirring the to-be-processed liquid of viscosity 100Pa * s by normal rotation. It is a graph which shows the simulation result which concerns on the stirring efficiency at the time of stirring the to-be-processed liquid with a viscosity of 100 Pa.s by reverse rotation. It is a graph which shows the simulation result which concerns on the stirring efficiency at the time of stirring the to-be-processed liquid with a viscosity of 1000 Pa.s by forward rotation. It is a graph which shows the simulation result which concerns on the stirring efficiency at the time of stirring the to-be-processed liquid with a viscosity of 1000 Pa.s by reverse rotation. It is the graph which put together the simulation result about the difference in the stirring efficiency by the forward / reverse rotation in each viscosity condition. It is explanatory drawing which shows typically the experimental result from which the wall surface height of the stirring tank inner wall to which a to-be-processed liquid adheres by the difference in the rotation direction of a stirring shaft.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
1 and 2, the stirring device 1 of the present embodiment is provided with a cylindrical stirring tank 3 into which various liquids 2 to be treated are charged and stored. The liquid to be treated 2 in the present embodiment is a non-Newtonian fluid of a type whose viscosity increases when force is continuously applied by stirring or the like, for example, an adhesive solution generated by adding various additives to a polymer solution. is there.

The agitation tank 3 includes a cylindrical body and a bottom plate having a semi-elliptical cross section attached to the lower end of the cylindrical body. A stirring shaft 5 is suspended from the central portion of the stirring tank 3 so as to be concentric with the cylindrical body of the stirring tank 3.
A motor (not shown) is connected to the agitation shaft 5, and the agitation shaft 5 is rotated in such a manner that the agitation shaft 5 can rotate forward and backward (normal rotation is in the R direction in FIG. 2). In addition, since the stirring shaft 5 penetrates the liquid surface of the liquid 2 to be treated stored in the stirring tank 3 upward, a winding phenomenon may occur due to the rotation of the stirring shaft 5.
A brace 6 is provided at the lower end of the stirring shaft 5. Two helical ribbon blades 7 are attached to the stirring shaft 5 and the arm 6. The helical ribbon blade 7 is provided so as to be along the axial direction of the stirring shaft 5, and the outer edge portion thereof is arranged near the inner wall of the stirring tank 3. When the stirring shaft 5 is rotated in the forward direction, the helical ribbon blade 7 rotates in a direction for scooping up the liquid 2 to be processed near the upper surface of the blade. On the other hand, when the stirring shaft 5 is rotated in the reverse direction, the helical ribbon blade 7 rotates in a direction to scrape the liquid 2 to be treated near the lower surface of the blade.

[Verification of stirring efficiency]
Subsequently, when the liquid 2 to be processed that has been put into the stirring tank 3 is stirred using the stirring device 1 configured as described above, the viscosity of the liquid 2 to be processed and the rotational direction of the helical ribbon blade 7 are determined. A simulation analysis was conducted to verify how different the stirring performance is. This simulation analysis is based on an analysis model having the same configuration as that of the stirring apparatus 1 of the present embodiment shown in FIGS.
The simulation was performed under the following conditions.
Analysis software program: Fluent (manufactured by ANSYS)
Number of rotations of helical ribbon wing: 20 min ⁻¹
Specific gravity of liquid to be treated: equivalent to water

  As shown in FIG. 3, in this simulation, first, arbitrary seven points such as the bottom C and the vicinity of the stirring axis D and G were selected in the stirring tank. Then, after adding and storing the liquid to be treated of each viscosity, a tracer liquid having the same viscosity as the liquid to be treated is dropped into the stirring tank in a state where the stirring shaft is rotated at the above speed, and the concentration at the seven points Change was tracked. Then, after dropping the tracer solution, the time until the relative concentration at 7 points becomes 1 as stirring is determined as the time when the concentration in the stirring tank becomes uniform, and this is used as an index for checking the stirring property. The viscosity of the liquid to be treated was simulated under each condition of 1 Pa · s, 10 Pa · s, 100 Pa · s, and 1000 Pa · s.

  When the simulation was performed, the results shown in FIGS. 4 to 11 were obtained. As is apparent from FIGS. 4 and 5, when the viscosity of the liquid to be treated is 1 Pa · s, the inside of the stirring tank is uniform, whereas the case where the stirring shaft is rotated forward is about 100 s. When rotating, it takes about 300 s, and stirring efficiency is better when rotating forward than when rotating backward.

  Further, as apparent from FIGS. 6 and 7, when the viscosity of the liquid to be treated is 10 Pa · s, the inside of the stirring tank is uniform, whereas the case where the stirring shaft is rotated forward is about 100 s. In the case of reverse rotation, it takes about 150 seconds, and the forward rotation is better than the reverse rotation for better stirring efficiency.

  As is clear from FIGS. 8 and 9, when the viscosity of the liquid to be treated is 100 Pa · s, the inside of the stirring tank is uniform because the stirring shaft is rotated forward or backward for about 300 seconds. Thus, there is no difference in the stirring efficiency between the forward rotation and the reverse rotation.

  Further, as apparent from FIGS. 10 and 11, when the viscosity of the liquid to be treated is 1000 Pa · s, the inside of the stirring tank is uniform in about 50 s both in the forward rotation and in the reverse rotation. There is no difference in the stirring efficiency between rotation and reverse rotation.

When the simulation results are summarized as shown in FIG. 12, when the viscosity of the liquid to be treated is 1 Pa · s and 10 Pa · s, the stirring efficiency is better when the stirring shaft is rotated forward than when it is rotated backward. On the other hand, when the viscosity of the liquid to be treated was 100 Pa · s and 1000 Pa · s, there was no difference between the two. This is considered to be due to the following reason.
When the stirring shaft is rotated in the forward direction, the helical ribbon blade rotates in the direction of scooping up the liquid to be processed, so that an upward flow of the liquid to be processed occurs near the inner wall of the stirring tank, which is the center of the stirring tank near the liquid surface. It is pushed in the direction, sucked in the vicinity of the stirring shaft, and a circulating flow is created that becomes a downward flow. On the other hand, when the agitation shaft is rotated in the reverse direction, the helical ribbon blade rotates in a direction to scrape the liquid to be treated, thereby causing a downward flow of the liquid to be treated near the inner wall of the stirring tank, which is centered near the bottom of the stirring tank. This creates a circulating flow that is pushed by the part and rises near the stirring axis.

Here, the strength of the upward flow, which is considered to have a strong relationship with the agitation efficiency in the agitation tank, is compared because the flow is in a direction against gravity. The upward flow near the inner wall of the stirring tank when the stirring shaft is rotated forward is due to the helical ribbon blade directly scooping up, whereas the upward flow near the stirring shaft when the stirring shaft is rotated backward is The downward flow caused by the helical ribbon wing scraping is a secondary one that rises in search of a refuge. For this reason, it is considered that the upward flow when the stirring shaft is rotated forward is stronger than the upward flow when the stirring shaft is rotated backward.
Here, the circulation flow by rotating the helical ribbon blade in the stirring tank appears remarkably when the liquid to be treated has a relatively low viscosity (for example, 10 Pa · s or less), but the liquid to be treated has a high viscosity. The tendency to become weaker and the influence on the fluidity in the agitation tank tend to decrease.
For this reason, the lower the viscosity of the circulating flow, the greater the difference in the strength of the upward flow due to the difference in forward and reverse rotation of the stirring shaft, and the reverse rotation of the stirring shaft. It is thought that there will be a big difference in the stirring efficiency. On the other hand, the higher the viscosity of the liquid to be treated, the gentler the circulating flow and the smaller the difference in the strength of the upward flow due to the difference between the forward and reverse rotations. Therefore, the difference in the stirring efficiency is narrowed to 100 Pa · s. It is thought that it will disappear from the standard.

[Comparative Experiment 1]
Next, in order to verify the difference in how the liquid to be treated 2 rises to the inner wall of the stirring tank 3 and rolls up to the stirring shaft 5 by rotating the stirring shaft 5 forward and backward. A comparative experiment was performed using the experimental device of the stirring device 1 described above.
This comparative experiment was performed under the following conditions.
Experimental machine capacity: 2L
Number of rotations of the helical ribbon blade 7: 20 min ⁻¹
Specific gravity of liquid 2 to be treated: equivalent to water

In this comparative experiment, two stirring tanks 3 storing the same amount of the liquid 2 to be processed were prepared, and the stirring shaft 5 was rotated forward and the other was rotated reversely and stirred. Then, when the viscosity of the liquid to be treated 2 was 100 Pa · s, the height of the liquid to be treated 2 attached to the inner wall surface of the stirring tank 3 and the height of the liquid to be attached to the stirring shaft 5 were compared in forward and reverse rotation.
As shown in FIG. 13, the liquid level of the liquid 2 to be treated in the stirring tank 3 (right side in FIG. 13) in which the stirring shaft 5 is rotated forward is low at the center of the stirring tank 3 and high near the inner wall of the stirring tank 3. It was. On the other hand, the liquid level of the liquid 2 to be treated in the stirring tank 3 (left side in FIG. 13) in which the stirring shaft 5 was rotated in the reverse direction was uniform in the stirring tank 3. Due to this difference, the wall height of the inner wall of the agitation tank 3 to which the liquid 2 to be treated was attached was markedly higher when the agitation shaft 5 was rotated forward than when it was reversely rotated.
Further, although the height of the stirring shaft 5 to which the liquid 2 to be treated is attached does not appear in FIG. 13, the forward rotation of the stirring shaft 5 was higher than the reverse rotation.

[Comparison experiment 2]
Comparative experiment 2 was performed in the same manner as comparative experiment 1 except that the above comparison was performed when the viscosity of the liquid to be treated was 1000 Pa · s.
Whether the stirring shaft 3 is rotated forward or backward, the height of the wall surface of the stirring tank 3 to which the liquid to be treated 2 adheres is the same as that of Comparative Experiment 1 performed when the viscosity of the liquid 2 to be treated is 100 Pa · s. It was about the same. On the other hand, when the stirring shaft was rotated forward, the height of the stirring shaft 5 to which the liquid 2 to be treated adhered was higher than when the liquid viscosity was 100 Pa · s. On the other hand, the adhering height of the stirring shaft 5 in the reverse rotation was about the same as that at 100 Pa · s.

  As described above, when the viscosity of the liquid to be treated 2 is 100 Pa · s and 1000 Pa · s, the stirring shaft 5 is rotated backward to the inner wall of the stirring tank 3 of the liquid 2 to be treated as compared with the case of normal rotation. It was confirmed that the uplift and the winding up to the stirring shaft 5 can be alleviated.

In addition, the relaxation of the above-mentioned rising phenomenon is due to the difference in the liquid level of the liquid 2 to be treated in the vicinity of the inner wall of the agitation tank 3 when the agitation shaft 5 is rotated in the forward direction and in the reverse direction. It seems that it originates in the difference in the direction of the circulating flow in the tank 3. FIG.
Moreover, although the direction of rotating the agitation shaft 5 in the forward direction is lower than the amount of liquid in the vicinity of the agitation shaft 5 in the reverse direction, the roll-up phenomenon can be alleviated by rotating the agitation shaft 5 in the reverse direction. Thus, it is considered that the influence of the circulating flow is relatively small when the viscosity of the liquid to be treated 2 is 100 Pa · s and 1000 Pa · s. That is, in this high viscosity region, the helical ribbon blades 7 scrape the liquid 2 to be treated near the liquid surface rather than the downward flow in the vicinity of the stirring shaft 5, which is a circulating flow generated by rotating the stirring shaft 5 forward. It is considered that the upward flow has a greater influence on the presence or absence of the roll-up phenomenon.

  As explained above, in the stirring method according to the present embodiment, when the stirring shaft 5 disposed in the stirring tank 3 is rotated forward in the method of stirring the liquid 2 to be processed in the cylindrical stirring tank 3, the helical When the ribbon blade 7 rotates in the direction to scrape the liquid to be treated 2 and the viscosity of the liquid to be treated 2 is 100 Pa · s or more, the helical ribbon blade 7 reversely rotates the stirring shaft 5 in the direction to scrape the liquid to be treated 2. Let In this high viscosity region, the stirring efficiency does not change even if the stirring shaft 5 is rotated forward or backward. Therefore, without lowering the stirring efficiency, the helical ribbon blade 7 rises to the inner wall of the stirring tank 3 and appears on the stirring shaft 5 when the helical ribbon blade 7 rotates the stirring shaft 5 in this high viscosity region. The inside of the agitation tank 3 can be evenly stirred while preventing roll-up.

  Further, the viscosity of the liquid to be treated 2 increases as the stirring proceeds, but when the viscosity of the liquid to be treated 2 is less than 100 Pa · s, the stirring shaft 5 is rotated forward so that the stirring is more efficient than the reverse rotation. It can be performed. In addition, since the rotation of the stirring shaft 5 is switched to the reverse rotation based on the time point when the viscosity becomes 100 Pa · s, the liquid 2 to be treated that appears in this high viscosity region is not applied to the stirring shaft 5 without lowering the stirring efficiency. The inside of the agitation tank 3 can be uniformly stirred while preventing rolling up and rising to the inner wall of the agitation tank 3.

  Further, in the stirring device according to this embodiment, when the viscosity of the liquid 2 to be processed stored in the cylindrical stirring tank 3 is less than 100 Pa · s, the stirring shaft 5 is rotated forward to be more efficient than reverse rotation. While stirring can be performed, when the pressure is 100 Pa · s or more, the stirring shaft 5 is rotated in the reverse direction, and the liquid 2 to be treated that appears in the high viscosity region is wound around the stirring shaft 5 without lowering the stirring efficiency. The inside of the agitation tank 3 can be uniformly agitated while preventing rising and rising to the inner wall of the agitation tank 3.

In addition, this invention is not limited to the said embodiment, Of course, various improvement and deformation | transformation are possible in the range which does not deviate from the summary of this invention.
For example, the liquid 2 to be treated may be a Newtonian fluid or a non-Newtonian fluid of a type whose viscosity decreases as stirring proceeds. Moreover, even if the stirring shaft is located at a position deviated from the central portion of the stirring tank, the roll-up phenomenon can occur, and therefore it is not necessary to provide it at the central portion. Even if the outer edge portion of the helical ribbon blade is not in the vicinity of the inner wall of the stirring tank, the outer edge portion may not be in the vicinity of the inner wall because it can be lifted up by rotation in the scraping direction. In the agitation tank, other types of blades such as an anchor blade and a paddle blade may be provided together with the helical ribbon blade.

DESCRIPTION OF SYMBOLS 1 Stirring apparatus 2 Liquid to be processed 3 Stirring tank 5 Stirring shaft 6 Arm 7 Helical ribbon blade

Claims (3)

Using a stirring device equipped with a cylindrical stirring tank into which the liquid to be treated is charged and stored, a stirring shaft disposed in the stirring tank, and a helical ribbon blade attached to the stirring shaft, In the method of stirring the liquid to be treated in the stirring tank by rotating the helical ribbon blade by rotation,
When the stirring shaft is rotated in the forward direction, the helical ribbon blade rotates in the direction of scooping up the liquid to be treated,
When the viscosity of the liquid to be treated is 100 Pa · s or higher, the stirring method is characterized in that the helical ribbon blade reversely rotates the stirring shaft in a direction to scrape the liquid to be treated. The viscosity of the liquid to be treated increases as the stirring proceeds,
While the viscosity of the liquid to be treated is less than 100 Pa · s, the stirring shaft is rotated forward,
2. The stirring method according to claim 1, wherein the rotation of the stirring shaft is switched to the reverse rotation based on a point in time when the viscosity of the liquid to be treated reaches 100 Pa · s. A cylindrical stirring tank into which the liquid to be treated is charged and stored;
A stirring shaft disposed in the stirring tank;
In a stirring device comprising a helical ribbon blade attached to the stirring shaft,
When the viscosity of the liquid to be treated is less than 100 Pa · s, the helical ribbon blade rotates the stirring shaft in a direction to scoop up the liquid to be treated, and the viscosity of the liquid to be treated is 100 Pa · s or more. Is a stirring device characterized in that the stirring shaft reversely rotates in the direction in which the helical ribbon blade scrapes the liquid to be treated.

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