JPH0648828U - Stirrer for high viscosity substances - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a stirring device for a high-viscosity substance that can cool even a thixotropic high-viscosity substance at a high speed and can well disperse additives throughout the substance to be stirred. [Composition] In a stirring device having a blade provided with a scraping member extending from a low position to a high position of a tank wall and having a water cooling jacket on the outer surface of the tank wall, the clearance between the scraping member and the inner surface of the tank wall is The small amount of clearance allows the substance to be stirred in the clearance to be mixed by the shear displacement caused by the rotational movement of the scraping member.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a stirrer for high viscosity substances, which is useful for stirring thixotropic high viscosity liquids.

[0002]

[Prior art]

 When stirring a liquid or the like with a stirrer, stirring must cause a large relative displacement of the liquid in the tank (ie convection mixing) and a local relative displacement inside the liquid (ie shear mixing). Done by.

Although the purpose of stirring is wide-ranging, promotion of heat transfer when the liquid in the tank is cooled from the outside, dispersion of additive substances, etc. are general purposes, and these purposes are mainly used. It is said that the above convective mixing contributes.

Conventionally, as a stirring device used for promoting cooling of the liquid in the tank and promoting dispersion of the additive, those shown in FIGS. 2 (A) to 2 (D) are known. In any of the stirring devices shown in FIGS. 2A to 2B, the cooling jacket 2'is provided on the outer surface of the tank wall. The stirring device shown in FIG. 2 (a) has a scaly blade 3 ′, and the stirring device shown in FIG. 2 (b) has a butterfly blade 3 ″. In the stirring device shown in (c), the squid blade 3'and the turbine blade 4'are provided, and in the stirring device shown in Fig. 3 (d), the butterfly blade 3 "and the turbine blade 4" are provided. I have each.

[0005]

[Problems to be solved by the device]

 The agitator shown in FIGS. 2 (a) to 2 (d) is intended for agitating a liquid having a viscosity range of 5000 cps to 600.000 cps, and is a vertical scraping member 32 'of an Ikari blade or a butterfly blade. The distance between the inner wall 11 'and the inner wall 11' is set to about 25 mm.

According to the experience of the present inventor using such a stirring device, when a liquid having a thixotropy in the above viscosity range is stirred by the above stirring device, a low viscosity region is obtained. Compared to the substance to be stirred, it takes a considerably long time to cool and the cooling rate is slow. In addition, the additive is not dispersed in the substance to be stirred in the liquid layer in contact with the inner surface of the tank wall, and the product in that portion must be removed as a defective product.

Therefore, the inventors of the present invention conducted various experiments and investigated the cause. The cause was that the scratching member was generated even if the scraping member was moved relative to the inner surface of the tank wall by the rotation of the blades. The contacting liquid layer is subjected to shearing force, which increases the fluidity due to thixotropic property, and due to the fluidization of this liquid layer, the shearing force is applied to the liquid layer near the inner surface of the tank wall which is separated from this liquid layer. It is presumed that the liquid near the inner surface of the tank wall remained without being transferred, and the heat transfer from the cooling jacket to the liquid in the tank due to stirring did not occur easily.

The object of the present invention is, based on the above findings, a stirrer for high-viscosity substances that can cool even thixotropic high-viscosity substances at a high speed and can well disperse additives throughout the substance to be stirred. To provide.

[0009]

[Means for Solving the Problems]

 The stirrer for highly viscous substances of the present invention has a blade having a scraping member extending from a low position to a high position on a tank wall, and a stirrer having a water cooling jacket on the outer surface of the tank wall. It is characterized in that the clearance between the tank and the inner wall of the tank is a small clearance that allows the substance to be stirred in this clearance to be mixed by shear displacement due to the rotational movement of the scraping member.

[0010]

[Action]

 The liquid layer in contact with the inner surface of the tank wall is mixed by shear displacement, and the heat transfer between the water cooling jacket and this liquid layer portion is well promoted. As a result, the substance to be stirred is cooled at a high speed.

Also, the dispersion of the additive is well promoted in the liquid layer in contact with the inner surface of the tank wall.

[0012]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing an embodiment of the present invention.

In FIG. 1, reference numeral 1 is a tank body, and a cooling water jacket 2 is provided on the outer surface thereof. Reference numeral 3 is a butterfly blade, and a scraping member 32 extending from a low position to a high position of the tank wall is attached to the tip of an inclined paddle 31 which is hollowed out like a spectacle. 4 is a Turbin wing.

The clearance a between the scraping member 32 and the inner wall surface 11 of the tank is a small clearance that allows the substance to be stirred in the clearance a to be mixed by shear displacement due to the rotational movement of the scratching member 32. Viscosity, rotation peripheral speed of the scraping member, etc. (inner diameter or tank volume of the tank and blade rotation speed) vary, but viscosity is 10,000 cps or more, tank volume is about 50 liters, butterfly blade rotation speed is 20 rpm to 90 rpm. In this case, the length is 15 mm or less.

In the above stirring device, the clearance between the scraping member 32 of the butterfly blade 3 extending from the low position to the high position of the tank wall and the tank wall inner surface 11 is sufficiently smaller than the conventional one. Even in the liquid layer portion near the inner wall 11 of the tank wall, which is separated from the scraping member 32, shear displacement due to the movement of the scraping member 32 can often be generated and shear mixed, and heat transfer between the cooling jacket 2 and the cooling jacket 2 can be effectively performed. And the substance to be stirred can be cooled at a high speed by a synergistic action with convection mixing by the turbine blade 4.

Of course, when the additive is added, the additive can be well dispersed even in the vicinity of the inner surface 11 of the tank wall, so that the liquid layer portion near the inner surface 11 of the tank wall does not have to be treated as a defective product, and the tank which has been agitated has not been treated. All the substances to be stirred inside can be transferred to the next process as good products, and good yield can be guaranteed.

In the above, if the clearance a between the scraping member 32 and the tank wall inner surface 11 is made extremely small (about 1 to 3 mm), the scraping member 32 can be expected to have an effect as a scraper, but the device is assembled. It is necessary to increase the accuracy, and the size of the clearance a is set in consideration of these points.

The above embodiment is a twin-screw mixer type in which a butterfly blade and a turbine are combined, but a twin-screw mixer type in which an Ikari blade and a turbine are combined, and a single-axis type using only a butterfly blade. Alternatively, it can be carried out as a uniaxial type using only the squid wing, and in these cases, the clearance between the scraping member extending from the lower part of the basin wall to the higher part of the basin wall and the inner wall of the basin wall However, a small clearance is set so that the substance to be stirred in this clearance can be mixed by the shear displacement caused by the rotational movement of the scraping member.

By using the stirring device of the present invention, the substance to be stirred can be cooled at high speed and with good heat efficiency, and the additive can be dispersed and mixed into all the substances to be stirred in the tank. This is clear from the comparison between the following examples and comparative examples.

Example As the stirring device, a biaxial mixer having a clearance of 7 mm and a capacity of 50 liters, which is a combination of a butterfly blade and a turbine shown in FIG. . The rotation speed of the butterfly blade was 43 rpm, and the rotation speed of the turbine blade was 425 rpm. The cooling jacket used had a heat radiation area of 0.224 m ² and a cooling water amount of 1100 kg / h, and the cooling water inlet temperature was 11 ° C.

Using this agitator, 40.4 kg of modified silicone sealant (viscosity: 400,000 cps, specific gravity: 1.45, specific heat: 0.45 Kcal / kg · ° C.) having an initial temperature of 63 ° C. is agitated. The time required for the average temperature to reach 30 ° C. was 49 minutes.

From the measurement result, the jacket overall heat transfer coefficient was calculated to be 174 Kcal / h · kg · ° C. In addition, when a pigment of a color different from that of the substance to be stirred was added during the stirring and the mixed state was observed, the layer thickness from the inner surface of the tank wall that can be judged as the unmixed layer was about 1 mm. The yield rate of defective parts was 99%.

Comparative Example The same stirring device as in the example was used except that the clearance between the scraping member and the inner surface of the tank wall was set to 16 mm, and the rotation speed of the blades, the water cooling condition by the cooling jacket, the agitated substance, etc. were all obtained in the example. Same as.

In this comparative example, it takes 128 minutes to cool the substance to be stirred to 30 ° C., and the overall jacket heat transfer coefficient is 72 Kcal / h · kg · ° C. Also, as in the example, when a pigment of a different color from the substance to be stirred was added during the stirring and the mixed state was observed, the layer thickness from the inner surface of the tank wall which can be judged as an unmixed layer was about 5 mm. The yield rate was only 95%.

[0025]

[Effect of device]

 As described above, the stirrer for highly viscous substances of the present invention sufficiently reduces the clearance between the scraping member extending from the lower part of the tank wall to the higher part of the blade and the inner surface of the tank wall in the blade ( Half), even in this clearance, the material to be stirred undergoes shear displacement and mixes, so heat transfer between the liquid layer in contact with the inner surface of the tank wall and the water cooling jacket can be promoted well, and the material to be stirred can be heat efficiently. Can cool at high speed.

Further, even in the liquid layer in contact with the inner surface of the tank wall, the dispersion can be promoted well, and the added substance can be dispersed without exception to all the substances to be stirred in the tank. In the case of stirring for the purpose of dispersion, good yield can be obtained. Can be guaranteed.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a different conventional example.

[Explanation of symbols]

 1 Tank main body 2 Water cooling jacket 3 Blade 32 Scratching member a Clearance between the scraping member and the inner surface of the tank wall

Claims (1)

[Scope of utility model registration request] 1. A stirring device having a blade having a scraping member extending from a low position to a high position of a tank wall and having a water cooling jacket on an outer surface of the tank wall, wherein a clearance between the scratching member and an inner surface of the tank wall is provided. A stirring device for high-viscosity substances, characterized in that the substance to be stirred in this clearance is a small clearance that can be mixed by shear displacement due to the rotational movement of the scraping member.