JP2006088146A - Agitator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an agitator with which a satisfactory vertical circulation flow can be attained overall in a tank and which can exhibit a suitable agitating characteristic. <P>SOLUTION: Openings 4 are arranged on an agitation blade 3 so as to satisfy the following condition that the ratio (i) of the gross area of openings 4 in the upper half U of the agitation blade 3 to that of the upper half U of the agitation blade 3 (the opening ratio in the upper half U of the agitation blade 3) is 45-80%, the ratio (ii) of the gross area of openings 4 in the lower half D of the agitation blade 3 to that of the lower half D of the agitation blade 3 (the opening ratio in the lower half D of the agitation blade 3) is 18-50% and the ratio (iii) of the opening ratio in the lower half D of the agitation blade 3 to that in the upper half U of the agitation blade 3 is 31-71%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a stirrer for stirring treatment for the purpose of mixing, dissolution, crystallization, reaction and the like.

  Conventionally, there are many examples in which small blades such as turbine blades, paddle blades, propeller blades, and the like are used in multiple stages as stirring blades of a stirrer. In a stirrer using these stirring blades, by increasing the blade rotation speed and increasing the flow rate of the liquid discharged from the blade in the radial direction, the liquid collides with the tank wall and rotates upward and downward. A circulating flow returning to the wing is generated, and mixing in the tank is performed.

  However, in the small blade, as shown in FIG. 14, sufficient vertical circulation flow is not formed over the entire tank, and a plurality of partition zones Z are formed between the upper and lower sides. Not good. In addition, the shape of the wing tends to be complicated, the manufacturing cost is high, and cleaning is difficult.

On the other hand, for example, in the flat blade described in Patent Document 1, since the blade shape is simple, the manufacturing cost can be suppressed and the cleaning can be easily performed. Since the discharge flow rate of liquid to the tank is large, there is an advantage that the stirring characteristics are good, and it is particularly suitable for stirring processing of high viscosity liquids and liquids that easily settle to the bottom of the tank.
Japanese Patent Laid-Open No. 10-174857

  However, even if it is a flat type wing, if it is the one described in Patent Document 1 or a complete flat plate without an opening, as shown in FIG. Since the discharge flow rate of the discharged liquid is equal, the discharge flow from the upper half of the wing collides with the discharge flow from the lower half of the wing, and a partition zone Z is formed between the upper and lower sides. As a result, the stirring characteristics are deteriorated.

  Then, this invention makes it a subject to provide the stirrer which can form sufficient vertical circulation flow over the whole inside of a tank, and can exhibit a suitable stirring characteristic.

  The stirrer according to the present invention is a stirrer in which a stirring shaft 2 that is rotatable from the outside of the tank is disposed in the center of the stirring tank 1, and a flat and rectangular stirring blade 3 is attached to the stirring shaft 2. The stirring blade 3 has a plurality of openings 4,... (I) the ratio of the opening area of the opening 4 in the upper half U to the total area of the upper half U of the stirring blade 3 (the opening in the upper half U of the stirring blade 3). Ratio) is 45 to 80%, and (ii) the ratio of the opening area of the opening 4 in the lower half D to the total area of the lower half D of the stirring blade 3 (opening ratio in the lower half D of the stirring blade 3) is 18 to 50 %, (Iii) The ratio of the opening ratio in the lower half D of the stirring blade 3 to the opening ratio in the upper half U of the stirring blade 3 is 31 to 71%.

  According to the stirrer having the above configuration, the opening ratio in the upper half U of the stirring blade 3 is large, the opening ratio in the lower half D is small, and the discharge flow rate of the stirring object discharged in the radial direction from the lower half D is: It becomes larger than the discharge flow rate of the stirring object discharged from the upper half U in the radial direction. Therefore, a vertical circulation flow from a strong discharge region to a weak discharge region, that is, a continuous vertical circulation flow from the lower part to the upper part of the stirring tank 1 is formed. As a result, the stirring target is totally stirred without forming a partition zone.

  That is, the stirrer according to the present invention increases the opening ratio in the upper half of the stirring blade, decreases the opening ratio in the lower half, and optimizes the opening ratio so that the entire inside of the tank can be obtained. Therefore, a sufficient vertical circulation flow can be formed, and suitable stirring characteristics can be exhibited.

  Hereinafter, an agitator according to an embodiment of the present invention will be described with reference to FIG.

  1 is a cylindrical stirring tank, and a stirring shaft 2 is disposed at the center of the tank 1. The stirring shaft 2 has a lower end supported through a bearing (not shown) provided at the bottom of the tank, and an upper end connected to a driving device (not shown) on the tank top via a coupling (not shown). Yes.

  3 is a flat stirring blade provided with a plurality of openings 4, which has a rectangular shape, and is attached to the stirring shaft 2 at the center in the width direction of the stirring blade 3. In the opening 4, the opening ratio in the upper half U of the stirring blade 3 (the ratio of the total opening area to the total area of the upper half U of the stirring blade 3 (including the total opening area of the opening 4 in the upper half U)) is stirred. The upper half so as to be larger than the opening ratio in the lower part D of the blade 3 (the ratio of the total opening area to the total area of the lower half D of the stirring blade 3 (including the total opening area of the opening 4 in the lower half D)). U is more arranged. In the case of the present embodiment, four openings 4 having the same opening area are provided in the upper half U of the stirring blade 3 with a predetermined interval, and three openings 4 are provided in the lower half D of the stirring blade 3 with a predetermined interval. One is formed.

  A baffle plate 5 is a side wall surface of the agitation tank 1, and a plurality of baffle plates are attached at a predetermined interval in the circumferential direction (only one is shown in the figure). The baffle plate 5 is continuous along the axial direction from the lower side to the upper side of the side wall surface of the stirring tank 1, and has a characteristic of raising the stirring object discharged from the stirring blade 3 to the upper part of the stirring tank 1. Yes.

  The stirrer which concerns on this embodiment consists of the above structures, and next, the stirring characteristic of the stirrer which concerns on this embodiment is demonstrated based on FIG.

The discharge flow rate of the stirring object discharged in the radial direction from the blade is generally proportional to the product of the unit width area in the axial length direction of the stirring blade 3 and the cube of the outer diameter in the unit width area. Are known. Therefore, when the opening ratio in the upper half U of the stirring blade 3 is large and the opening ratio in the lower half D is small like the stirring blade 3 according to the present embodiment, the discharge flow rate Q ₁ of the stirring object in the lower half D is More than the discharge flow rate Q ₂ of the stirring object in the upper half U.

Then, due to the difference in the discharge flow rate between the upper half U and the lower half D of the stirring blade 3, that is, the difference in discharge strength, the vertical circulation flow R ₁ from the strong discharge region to the weak discharge region, that is, the stirring tank A vertical circulation flow R ₁ continuous from the lower part to the upper part of ₁ is formed. As a result, since the stirring target can be stirred as a whole without forming a partition zone, the stirring characteristics are improved.

Moreover, after reaching the upper part, the vertical circulation flow R ₁ moves from the side wall side of the stirring vessel 1 to the center side and becomes the vertical circulation flow R ₂ that moves downward along the stirring shaft 2 and the stirring blade 3. Returning to the bottom of the tank, since the stirring blade 3 is provided with a plurality of openings 4, the stirring object being lowered is sheared and subdivided by these openings 4, and the subdivided stirring object is stirred by the stirring blade. No. 3 is wound into a fine vortex generated on the rear side in the rotation direction and is stirred more finely.

In FIG. 2, for easy understanding, the discharge flow rates (discharge flow) Q ₁ and Q ₂ and the vertical circulation flows R ₁ and R ₂ are shown only on one side. Needless to say, the same flow mode occurs in the entire region in the direction.

  Here, the present inventor conducted various experiments to determine how the aperture ratio of the stirring blade 3 should be set.

FIG. 4 shows the result of performing the following experiment, plotting the experimental result (FIG. 3), and drawing the boundary line.
<Experimental conditions>
-Tank inner diameter D (inner diameter of the barrel of the stirring tank 1): 310 mm
Blade diameter d (width of stirring blade 3): 165 mm
Blade height B (height from the lowest position of the tank bottom to the uppermost end of the stirring blade 3): 295 mm
Liquid depth L (height from the lowest position of the tank bottom to the liquid level): 357 mm
-Tank bottom shape: semi-elliptical-Baffle plate: Yes-Liquid volume: 25 liters-Liquid viscosity: 1 cp (water)
・ Agitation power: 0.2 kW / m ³
<Experiment method>
The flow state is observed using an iodine reduction decolorization method. That is, the liquid in the stirring tank 1 is colored reddish brown with iodine, and after stirring the decoloring liquid, the progress of the decoloring of the liquid in the tank and the presence or absence of a partition zone are observed (VTR recording). . For example, Mixing (1975) Shinji NAGATA John Wiley & Sons, P187, 4.3.1 Method of Measuring Mixer Performance, Handbook of Industrial Mixing, John Willy & Sons, P167, 4-4.3 Approximate Mixing Time Measurement with This is a well-known method disclosed in Colorimetric methods. Incidentally, “◯” is an evaluation with respect to the case where the flow discharged from the lower part of the stirring tank 1 smoothly reaches the upper part, and one vertical circulation flow continuous in the vertical direction is formed, and “△” Although the flow discharged from the lower part of the stirring tank 1 has almost reached the upper part, it is an evaluation for the case where the flow toward the center side is seen partway. It is an evaluation for a case where the data is divided.

  FIG. 6 shows the approximate curve by performing the same experiment under the same experimental conditions as above, measuring the time from stirring until the solution in the tank is completely decolored, and plotting the experimental result (FIG. 5). It is what I subtracted. The ratio of mixing time means the ratio of each mixing time when the optimum value of mixing time (in the experiment, 3.1 seconds) is 100%, and the upper and lower aperture ratio is the ratio of the stirring blade 3 The ratio of the aperture ratio in the lower half D of the stirring blade 3 to the aperture ratio in the upper half U. Moreover, the optimum value (average value) of the mixing time means an average of 10 mixing time data in a region where the mixing time is short. Specifically, among the fifth data (3.1 seconds) to the 14th data (3.4 seconds) from the top of FIG. 5, the 13th data (4.0 seconds) is a singular point. And the average of the remaining nine data. FIG. 7 shows approximate curve data.

  3 and 4, the aperture ratio in the upper half U of the stirring blade 3 is 45 to 80%, the aperture ratio in the lower half D is 18 to 50%, and the ratio of the upper and lower aperture ratios of the stirring blade 3 is If it is 31 to 71% (a region sandwiched between y = 0.31x and y = 0.71x, where y is the vertical axis and x is the horizontal axis), the flow state (mixing characteristics) is good, Furthermore, if the ratio of the upper and lower aperture ratios of the stirring blade 3 is reduced to 37 to 65% (region sandwiched between y = 0.37x and y = 0.65x), the flow state (mixing characteristics) is further improved. I understand that

  From FIG. 6 and FIG. 7, the upper and lower opening ratio of the stirring blade 3 falls within the range of 110%, and the ratio of the upper and lower openings of the stirring blade 3 falls within the range of 120%. It can be seen that the aperture ratio of is 31 to 71%. This fact is consistent with the above facts derived from FIGS.

  From the above, the opening ratio of the stirring blade 3 is (1) the opening ratio in the upper half U of the stirring blade 3 is 45 to 80%, the opening ratio in the lower half D is 18 to 50%, and the stirring blade 3 It is preferable that the ratio of the upper and lower aperture ratios is 31 to 71%. (2) More preferably, the aperture ratio in the upper half U of the stirring blade 3 is 45 to 80%, and the aperture ratio in the lower half D is 18 to 50. %, And the ratio of the upper and lower aperture ratios of the stirring blade 3 is 37 to 65%.

  In addition, the stirrer which concerns on this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of this invention.

  For example, in the above embodiment, the upper and lower aperture ratio is 31% or more, more preferably 37% or more, and 71% or less, more preferably 65% or less, but the mixing time ratio is 100%. %, It is more preferable that it is 46% or more and 56% or less, and considering that the mixing time ratio is lower than 99%, it is 48% or more. Further, it is more preferable that it is 54% or less.

  Moreover, in the said embodiment, although the aperture ratio in upper half U was 45% or more and 80% or less, when only the evaluation is "(circle)", it is 50% or more, More preferably, it is 76% or less.

  Further, in the above-described embodiment, the horizontally-long rectangular openings 4 are arranged so as to be vertically arranged. However, as shown in FIG. In order to give different aperture ratios, the lengths of the openings 4 are made different), as shown in FIG. 9, the sizes of the openings 4 are made different, and they are appropriately arranged, as shown in FIG. FIG. 11 shows an aspect in which the agitation shaft 2 is arranged in a non-linear symmetry, as shown in FIG. 11, an aspect in which the phases of the left and right openings 4 are shifted in the axial direction across the agitation shaft 2, as shown in FIG. The aspect in which the openings 4 are arranged in a staggered manner in the axial length direction, the aspect in which the openings 4 are arranged in a checkered pattern as shown in FIG. If the opening ratio is smaller than half D, the shape, number, size and arrangement of the opening 4 No preference.

  Moreover, in the said embodiment, although opening is formed by making a hole in a board | plate material, for example, like an anchor type wing | blade, it is set as a flat and rectangular stirring blade, and between each structural member, it combines. The gap may be an opening.

  Moreover, in the said embodiment, although the lower end of the stirring shaft 2 is supported by the tank bottom part, the aspect which is spaced apart and supported from this tank bottom part may be sufficient.

  Moreover, in the said embodiment, although the drive device for rotationally driving the stirring shaft 2 from the tank outside is provided in the tank top part side, you may provide this drive apparatus in the tank bottom part side.

  Moreover, in the said embodiment, although the baffle plate 5 is provided, this baffle plate 5 is not an essential structure in this invention.

  Further, the tank inner diameter D, the blade diameter d, the blade height B, and the liquid depth L are not particularly limited, but generally, the blade diameter ratio d / D (blade diameter d / tank inner diameter D) is set. If the blade height ratio B / D (blade height B / tank inner diameter D) is set to 50 to 100% and the liquid depth ratio L / D (liquid depth L / tank inner diameter D) is set to 10 to 150%. Good.

The front view of the stirrer which concerns on this embodiment is shown. The conceptual diagram for demonstrating the stirring characteristic of the stirrer which concerns on the same embodiment is shown. The data table of the stirring characteristic (mixing characteristic) in the relationship between the aperture ratio in the upper half of a stirring blade and the aperture ratio in a lower half is shown. The graph showing the quality of the stirring characteristic (mixing characteristic) in the relationship between the aperture ratio in the upper half of a stirring blade and the aperture ratio in a lower half is shown. The data table of the relationship between the ratio of the aperture ratio in the lower half with respect to the aperture ratio in the upper half of the stirring blade and the ratio of the mixing time is shown. The graph showing the relationship between the ratio of the aperture ratio in the lower half to the aperture ratio in the upper half of the stirring blade and the ratio of the mixing time is shown. The data table of the approximate curve in FIG. 6 is shown. The front view of the stirrer which concerns on other embodiment (the 1) is shown. The front view of the stirrer which concerns on other embodiment (the 2) is shown. The front view of the stirrer which concerns on other embodiment (the 3) is shown. The front view of the stirrer which concerns on other embodiment (the 4) is shown. The front view of the stirrer which concerns on other embodiment (the 5) is shown. The front view of the stirrer which concerns on other embodiment (the 6) is shown. The conceptual diagram for demonstrating the stirring characteristic of the stirrer concerning the conventional small blade is shown. The conceptual diagram for demonstrating the stirring characteristic of the stirrer which concerns on the conventional large wing | blade is shown.

Explanation of symbols

1 ... stirred tank, 2 ... stirring shaft, 3 ... stirring blade, 4 ... opening, 5 ... baffle, R _1, R ₂ ... vertically circulating flow, Q _1, Q ₂ ... discharge flow rate

Claims (1)

In a stirrer in which a stirring shaft (2) rotatable from the outside of the tank is disposed in the central portion of the stirring tank (1), and a flat and rectangular stirring blade (3) is attached to the stirring shaft (2). The stirring blade (3) is provided with a plurality of openings (4,...) Under the following conditions.
(I) Ratio of opening area of opening (4) in upper half (U) to total area of upper half (U) of stirring blade (3) (opening ratio in upper half (U) of stirring blade (3)) Is 45-80%
(Ii) Ratio of opening area of opening (4) in lower half (D) to total area of lower half (D) of stirring blade (3) (opening ratio in lower half (D) of stirring blade (3)) 18-50%
(iii) The ratio of the opening ratio in the lower half (D) of the stirring blade (3) to the opening ratio in the upper half (U) of the stirring blade (3) is 31 to 71%

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