JP3198819B2 - Stirrer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to batch processing of various viscous fluids in small-quantity, multi-product production in the chemical, pharmaceutical and food industries, etc., and changes in liquid viscosity over a wide range due to reaction, dissolution or dispersion during operation. The present invention relates to a stirring device that can be used in a process.

[0002]

2. Description of the Related Art The flow characteristics of a liquid in a stirring tank differ greatly between a low viscosity region and a high viscosity region, and the flow characteristics and mixing characteristics also change. In particular, in the low viscosity region, a poor rotation portion is formed on the shaft portion due to the co-rotation phenomenon between the fluid and the blade, and poor mixing occurs. Therefore, it is generally considered essential to install a baffle plate in the tank. However, the effect of the baffle plate, which is indispensable in the low-viscosity region, is reduced due to the increase in the viscosity of the liquid, and in the high-viscosity region, it causes stagnation and adhesion of the back surface of the baffle plate. Therefore, in the case of a process in which the viscosity changes in a very wide range such as a polymer polymerization process, it is difficult to set the stirring blade. That is, it is difficult to obtain almost the same stirring effect from low viscosity to high viscosity with the same conventional stirring device.

[0003] In addition to the above-mentioned good stirring efficiency, the stirring device has low investment costs, easy cleaning, easy maintenance, and low running costs such as electricity bills. Is required. Chemical Handbook Revision 4
The plate (5th printing on December 20, 1985) includes a turbine type, a propeller type, and a well-known conventional stirring blade.
Examples include an anchor type, a Faudler type, a double helical type, and a screw type. It is said that turbine-type, propeller-type, anchor-type, and Faudler-type stirring blades are mainly suitable for stirring and mixing low-viscosity liquids and are not very suitable for stirring high-viscosity liquids.

As shown in FIG. 1, the double helical-type stirring blade has band-shaped blades arranged twice in a spiral shape. The double helical stirring blade is said to be suitable for stirring a high-viscosity liquid, and is designed so that even a high-viscosity liquid flows sufficiently in the vertical direction of the stirring tank. The double helical agitating blade is a wide band-shaped blade, which applies fluid by lifting liquid from the lower part to the upper part. On the other hand, in the central part, the liquid lifted from the lower part flows from the upper part to the lower part. In this way, even a highly viscous liquid flows smoothly in the vertical direction. As shown in FIG. 2, Japanese Patent Publication No. 1-37173 discloses a stirring shaft 22 provided at the center of a stirring tank 21.
A flat blade 23 along the inner surface of the bottom wall of the stirring tank 21 is provided at a lower part of the stirring tank 21, and a lattice-shaped blade 24 continuous with the flat blade 23 is provided on the upper portion of the stirring shaft 22. A plurality of baffles 25 along the axial direction from the lower part to the upper part
Are provided at intervals.

[0005] At a plant show held in Makuhari in November 1993, Shinko Pantech's catalog distributed a novel full zone type stirring blade as shown in Fig. 3. I have. A parallel-plate-type blade 31 is provided above a stirring shaft provided at the center, and an S-shaped blade 32 is formed below the parallel-plate-type blade 31 at an angle with the upper parallel-plate-type blade 31. Is provided.

[0006]

The double helical stirring blade is suitable for stirring a high viscosity liquid because of its structural principle. However, the yield of high-viscosity products is inferior to other stirring blades due to the complicated shape of the blade, cleaning is difficult due to the complicated shape of the blade, and an extremely large motor is required due to a large rotating load. There are drawbacks such as the necessity and the high running load due to the large rotating load. The lattice-shaped stirring blade disclosed in Japanese Patent Publication No. 1-373173 can be stirred with smaller power compared to a double helical blade. Certainly, low-viscosity liquids can be sufficiently agitated with a small amount of power, but even with baffles, high-viscosity liquids have insufficient stirring in the vertical direction, so the stirring efficiency is not as good as double helical blades. Was. In addition, a stagnant portion is easily formed on the back surface of the baffle plate, and this has the disadvantage that the system becomes non-uniform or some reaction systems gel.

In the case of a low-viscosity liquid, the full-zone stirring blade shown in FIG. 3 can obtain sufficient mixing with a small power. The full zone stirring blade is similar to the lattice stirring blade described above,
Since there is a disadvantage that the stirring in the vertical direction is insufficient, the stirring efficiency with a high-viscosity liquid is not sufficient. Conventional stirring blades have the above-mentioned problems, and there is no satisfactory process in which the viscosity changes over a wide range. The double helical stirring blade is a stirring blade that can be widely used from low viscosity region to high viscosity region,
It has the problems already described.

[0008] An object of the present invention is to provide a stirring blade which does not have the above-mentioned problems and can be widely used from a low viscosity region to a high viscosity region.

[0009]

According to the present invention, as shown in FIGS. 4A and 4B, a stirrer shaft 41 provided at the center of a stirrer tank is provided in parallel with the stirrer shaft 41. The flat wings 42 are mounted and the flat wings 44 are spaced below the wings at an angle of 20 to 90 degrees.
Is attached to the uppermost portion of the flat blade 42 so as to form an angle of 100 to 170 degrees with the flat blade 42.
And the wings 45 are formed at the bottom of the wings 44 so as to form an angle of 100 to 170 degrees with the wings 44.
Is attached to the stirring device. In the present invention, the presence of the blades 43 and 45 promotes the flow in the vertical direction and improves the stirring efficiency even with a high-viscosity liquid.

The height 42a of the flat wing 42 and the flat wing 44
Are equal lengths. Width 4 of flat wing 42
It is desirable that the width 2b and the width 44b of the flat blade 44 be the same and in the range of 30% to 80% of the diameter of the stirring tank. In the case of a low-viscosity liquid, stirring can be sufficiently performed even if the length is close to 30% of the diameter of the stirring tank, but if it is smaller than 30%, the stirring efficiency deteriorates. In the case of a high-viscosity liquid, the length is preferably close to 80% of the diameter of the stirring tank. However, if it is more than 80%, the stirring torque is rapidly increased due to the effect of the wall of the stirring tank. In FIG. 4A, the apparent height 43a of the wing 43 is the same as the apparent height 45a of the wing 45, and preferably ranges from 20% to 100% of the width 42a of the flat wing 42. If it is less than 20%, the flow in the vertical direction is less than the flow in the radial direction, so that the stirring efficiency is deteriorated. On the other hand, if it is larger than 100%, the flow in the radial direction decreases, and the stirring efficiency also decreases.

The interval between the flat blades 42 and the flat blades 44 is 10% to 10% of the height 42a (or 44a) of the flat blades 42.
A range of 50% is desirable. The reason why the interval between the two flat blades is increased is to divide the liquid, which becomes difficult to flow when the viscosity becomes high, into two upper and lower parts to facilitate the flow. If the interval is smaller than 10%, the effect of increasing the interval can hardly be expected, and if it exceeds 50%, there may be places where stirring itself becomes defective. The flat wing 42
The angle formed by the flat wings 44 is preferably 20 degrees to 90 degrees. If this angle is smaller than 20 degrees, the flow in the vertical direction is not performed efficiently. Due to the delay of the angle and the existence of the blades 43 and 45, the vertical flow and the radial flow are efficiently performed.

The angle between the flat wings 42 and the wings 43 and the angle between the flat wings 44 and the wings 45 are the same, preferably in the range of 100 ° to 170 °, more preferably 120 °.
A range of degrees to 160 degrees is good. If this angle is smaller than 100 degrees, the flow in the up and down direction is likely to occur, but the discharge flow rate will be small and the agitation in the up and down direction will be poor.
When the angle is larger than 170 degrees, the flow in the radial direction is more central than the flow in the vertical direction, and almost no vertical flow can be expected. The blades 43 and 45 are both attached to the plate blades 42 and 44 so as to flush the liquid downward. To achieve this purpose, the wing 43
The blade 45 is mounted so as to be in front of the plate blade 42 with respect to the rotation direction, and the blade 45 is mounted behind the plate blade 44 with respect to the rotation direction. In another embodiment, wings may be mounted on the opposite side, but in this case, the effect of flushing the liquid upward can be obtained.

Generally, therefore, the liquid level often fluctuates during the dissolution process, the reaction process, etc., but in the present invention, the flow is promoted in both the uppermost portion and the lowermost portion of the stirring blade in the vertical direction. Since the auxiliary wings are provided, fluctuations in the stirring efficiency with respect to fluctuations in the liquid level can be prevented. However, the effect of the stirring blade of the present invention can be best exhibited when the liquid level is about 10% of the total height 46 of the stirring blade in FIG.
%. The thickness of the stirring blade shown in FIG. 4A is sufficient as long as the high-viscosity liquid can be stirred at a sufficient speed and does not deform. The material of the stirring blade may be a general material. That is, the material is selected from iron, stainless steel, tantalum, glass, ceramics, copper, aluminum, and the like depending on the purpose, but is not limited to these materials.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments. In FIG. 5, reference numeral 51 denotes an inner diameter of 90 mm and a height of 20 mm.
In the center of the stirring tank 51, a stirring shaft 52 having a diameter of 6 mm and extending to the vicinity of the bottom wall is provided.
A pair of flat blades 53 and 55 are attached in parallel to the stirring shaft 2. The flat wings 53 and 55 have a width of 35 mm and a radial length of 60 mm, the flat wings 53 and the flat wings 55 have an interval of 10 mm, and the flat wings 53
And the plate-like wing 55 were installed so as to form an angle of 45 degrees.
At the uppermost part of the flat wing 53, a wing 54 having a width of 15 mm and a radial length of 60 mm at an angle of 45 degrees with the flat wing 53 is attached. 5
A wing 56 of the same size as the wing 54 was attached at an angle of 5 and 45 degrees. The blades 54 and 56 are positioned as shown in FIG. 5 such that the liquid flows downward with respect to the flat blades 53 and 55 when the stirring shaft of FIG. 5 rotates clockwise. Attached to.

The above-described stirring tank is filled with the test liquid so that the liquid level is about 120 mm, the uppermost part of the stirring blade is located at a position about 10 mm from the liquid level, and the bottom of the stirring tank is The stirring blade was installed so as to be about 10 mm above and at the bottom of the stirring blade. (Test liquid) Ethylene glycol-added glycerin (Newpole H90000 manufactured by Sanyo Chemical Co., Ltd.) as a test liquid
Was used. (Viscosity) The viscosity was adjusted by appropriately adding water to the ethylene glycol-added glycerin, and the viscosity was measured at 25 ° C. with a B-type rotational viscometer. (Torque, rotation speed) A test motor with a torque meter and a tachometer was used. (Mixing time) A small amount of an aqueous sodium hydroxide solution and phenol phthalene were added to the test solution in advance, and the test solution was colored reddish brown. The number of revolutions of the stirring blade is adjusted in advance so as to have a predetermined torque. The mixing time was set.

[0016] A plurality of test liquids having different viscosities are prepared.
Table 1 shows the results of measuring the mixing time while keeping the rotation torque constant.
Shown in

[0017]

Comparative Example As a comparative example, a double helical stirring blade and a full zone stirring blade were experimentally manufactured, and the mixing time was measured in the same manner. The results are shown in Table 1.

[0018]

[Table 1]

As is clear from Table 1, the torque was almost the same as in the full zone, and the mixing time was greatly reduced in the viscosity range of this embodiment. Particularly on the high viscosity side, the mixing time was significantly reduced. The mixing time is overwhelmingly shorter than that of a double helical type stirring blade which has been said to be effective for high viscosity stirring.

[0020]

The present invention has the above-described structure and has the following effects. By arranging two large flat wings at an angle, dividing the liquid flow into upper and lower two areas, and arranging angled wings at the top and bottom of the two flat wings In addition, the flow in the up-down direction is promoted, and a synergistic effect with the divided flow of the above-mentioned two regions significantly improves the stirring efficiency per unit torque as compared with the conventional stirring blade. The stirring load per unit rotation speed of the stirring blade of the present invention is almost the same as the conventional full zone which is said to have a small stirring load, and is considerably smaller than the double helical type. The product recovery rate of the stirring blade of the present invention is almost the same as the recovery rate in the full zone, and is considerably better than that of the double helical. The cleaning of the stirring blade of the present invention is as simple as the full zone, and is also overwhelmingly easier to clean than the double helical.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a conventional double helical stirring blade.

FIG. 2 is a cross-sectional view of a conventional lattice type stirring blade.

FIG. 3 is a cross-sectional view of a conventional full zone type stirring blade.

FIG. 4 is a schematic view showing the present invention and a schematic view when a stirring blade is rotated.

FIG. 5 is a sectional view showing an embodiment of the present invention.

[Brief description of reference numerals]

 21: Stirring tank 22: Stirring shaft 23: Flat blade 24: Lattice blade 25: Baffle plate 31: Parallel flat blade 32: S-shaped blade 41: Stirring shaft 42: Flat blade (upper) 42a: Flat blade Height 42b of wing 42b: Width of flat wing 42 43: Wing (upper) 43a: Apparent height of wing (upper) 44: Flat wing (lower) 44a: Height of flat wing 44 44b: Flat Width of blade 44 45: Blade (lower) 45a: Apparent height of blade (lower) 46: Total height of stirring blade 51: Stirring tank 52: Stirring shaft 53: Flat blade 54: Blade 55: Flat blade 56: Wing

Claims (3)

(57) [Claims] 1. A stirring shaft provided at the center of the stirring tank,
A flat wing A is attached parallel to the stirring axis, and a flat wing B is attached below the wing at an interval of 20 to 90 degrees with an interval therebetween. The wing A1 is attached to the flat wing A at an angle of 100 to 170 degrees with the flat wing B, and the wing B1 is formed at the bottom of the flat wing B with the flat wing B at an angle of 100 to 170 degrees. Is attached , the apparent height of wings A1 and B1
20% of the width (42a) of the flat wing A
From 100 to 100% . 2. The stirrer according to claim 1, wherein the distance between the flat blades A and the flat blades B is 10% to 50% of the height of the flat blades A. 3. A stirrer, wherein a baffle plate is installed in a stirrer provided with the stirrer according to claim 1.