JP3820313B2 - Agitator blade structure of vertical agitator - Google Patents

Description

[0001]
[Field of the Invention]
The present invention relates to a stirring device used for stirring in various tanks of various fluids, semi-fluids, powders, and the like, and more particularly, to a stirring blade structure of a vertical stirring apparatus applied to an acute angle conical bottom type stirring tank.
[0002]
[Prior art]
In general, this type of agitation device supports a rotating shaft having an agitating blade at the center of the agitating tank so as to protrude from the tank, and rotates the agitating blade by rotating the rotating shaft from the outside of the tank. At the same time, a swirl flow and a vertical circulation flow are generated in the processed material (substance to be stirred) in the tank to perform stirring and mixing. As conventional stirring blades, discharge-type blades such as turbine blades, paddles, propellers, and receding blades, or shear-type stirring blades such as gates, helical ribbon blades, screws, and anchors are known.
[0003]
FIG. 7 is a cross-sectional view of a conventional stirring device using two-stage turbine blades. In this example, the stirring tank 20 has a conical bottom shape with a half apex angle α at the bottom, and a rotating shaft 21 that is rotationally driven from outside is provided at the center of the tank so as to extend along the entire length of the tank. One or a plurality of stirring blades 23 are attached. The stirring blade 23 discharges the liquid to the surroundings by the rotation of the rotating shaft 21, and performs the action of circulating the liquid in the tank by the discharge flow. A coil 24 may be installed on the inner periphery of the tank 20.
[0004]
[Problems to be solved by the invention]
With a conventional stirring blade, for example, in the case of (1) a high liquid depth stirring tank (the ratio of the liquid depth L from the tank bottom to the liquid surface and the tank inner diameter D is L / D> 1.5) Cannot be achieved. (2) In an acute angle conical bottom type stirring tank having a half apex angle of 60 ° or less, as seen in FIG. 7, a horizontal arm-shaped blade similar to the stirring blade 23 in the tank body is provided below the rotating shaft 21. Since only one 30 is provided at most, a liquid retaining portion 27 is inevitably generated at the tip portion of the conical, and mixing does not proceed at that portion. In particular, when the coil is installed on the periphery of the tank, the above-mentioned problems (1) and (2) become more remarkable.
[0005]
With reference to FIG. 7 and FIGS. 8 to 11, the above-described conventional problems will be described in detail. As shown in FIG. 8, when the discharge type stirring blade 23 is used in a single stage, the blade 23 is usually installed in the vicinity of TL (joining line between the straight body portion and the conical portion of the tank). In this state, since the moving distance from the tank bottom 20a to the liquid level 25 is long, the flow velocity is attenuated while the discharged liquid is moving (portion A in FIG. 8), and upper and lower uniform mixing is achieved. In other words, stagnation occurs in part B of FIG.
[0006]
In order to eliminate this non-uniform state, as shown in FIG. 9, there are cases where the stirring blades are used in a multi-stage configuration having two or more stages, but a collision of the discharge flow occurs between the blades 23a and 23b, which is denoted by reference numeral 26. Thus, the state is as if partition walls were provided in the middle of the upper and lower sides of the tank, and the uniform mixing of the upper and lower sides was rather hindered by the partition-like liquid phase.
[0007]
In the conical bottom type agitation tank 20 having a half apex angle of 60 ° or less in FIGS. 7, 10, and 11, the cross-sectional area becomes smaller as the tip of the conical is approached, so that fluid resistance is easily generated when the liquid flows. Therefore, in reality, the liquid does not flow up to the tip of the tank, and so-called flow separation occurs in which the liquid tends to flow in a direction with less resistance. As a result, a liquid retaining portion 27 is generated at the tip portion of the conical. This tendency is stronger as the viscosity increases. Even with the paddle-shaped stirring blade 30 at the bottom of the tank, the retention of this portion cannot be eliminated. In FIG. 7, the hatched portion indicates a portion where the liquid is poorly flowed.
[0008]
In addition, for shear type stirring blades such as gates, helical ribbon blades, screws, anchors, etc., it is generally said that they rotate at a low speed and promote mixing by lifting or scraping the liquid. These shear-type wings perform as they are nominally limited to so-called laminar flow areas with a Re number of at least 100 or less, otherwise the ability to form a liquid up-and-down circulating flow is extremely high. Low. When the Re number is 100 or more, the upper and lower mixing is difficult to proceed. The Re number is the number of ray nozzles and is expressed by d ² nρ / μ. Here, d is the stirring blade diameter [m], n is the blade rotation speed [1 / s], ρ is the density [kg / m ³ ], and μ is the viscosity [kg / m · s].
[0009]
Furthermore, most of the conventional agitation devices have a blade shape and a combination of blades that form an upward flow (reference numerals 28 and 29 in FIG. 7) in the vicinity of the wall surface. In such a conventional blade shape, the center of an acute angle conical bottom is used. Then, it is not possible to form an upward flow. Furthermore, since the flow velocity attenuates in the middle under conditions of high liquid depth and coil, the inside of the tank does not become a single circulation flow, but a number of secondary circulation flows (flows isolated from the entire flow) 28 and 29 are formed. As a result, the uniform mixing throughout the tank is very poor.
[0010]
The present invention eliminates the above-mentioned conventional problems, uses a sharp conical bottom with a half apex angle of 60 ° or less , and uses a stirring tank in which a heat transfer coil is arranged near the inner wall of the bottom of the conical bottom shape. An object of the present invention is to provide a stirring blade structure of a vertical stirring apparatus that does not cause stagnation and that can achieve shortening of the uniform mixing time in the vertical direction, uniforming of the flow velocity in the vertical direction, and shortening of the heat transfer time.
[0011]
[Means for Solving the Problems]
The stirring blade structure according to the present invention includes a stirring tank having a bottom formed in an acute-angled conical shape with a half apex angle of 60 ° or less, a heat transfer coil installed along the inner wall of the bottom of the conical bottom of the stirring tank, In a vertical stirring apparatus having a rotating shaft that is disposed at the center of the stirring tank and is driven to rotate from the outside of the tank, and a stirring blade attached to the rotating shaft, the stirring blade is located at a bottom position of the stirring tank. and a conical bottom paddle part having disposed Rutotomoni the spreading from the rotating shaft in a radial direction and along the heat transfer coil installed in conical bottom shaped bottom of the stirring tank external.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Next, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a vertical stirring apparatus using a stirring blade structure according to one embodiment of the present invention. The stirring blade of this embodiment is composed of a conical bottom paddle portion 31 attached to the lower part of a stirring shaft (rotating shaft) 8. The conical bottom paddle portion 31 has a much larger area than the conventional stirring vane 30 at the bottom of the stirring tank shown in FIG. 7, and the outer shape of the conical bottom paddle section 31 is similar to that of the conical bottom bottom 7 of the stirring tank 32. A side shape 31a is formed which is close and substantially along the semi-acute angle shape of the bottom portion 7. The upper edge 31 b of the paddle part 31 is in the vicinity of the boundary position between the conical bottom-shaped bottom part 7 and the straight body part 6 of the stirring tank 32 when the stirring shaft 8 is assembled to the stirring tank 32.
[0013]
Further, in this embodiment, the number of blades of the paddle portion 31 is four around the stirring shaft 8 as shown in FIG. 2, but the present invention is not necessarily limited to this number of blades. Instead, two blades aligned in the diametrical direction, or three blades provided at regular intervals may be used. Above the conical bottom paddle portion 31, only the stirring shaft 8 is provided in this embodiment and no other blades are provided, but an appropriate blade can be attached to this portion. The paddle portion 31 may be structured to be inclined, refracted or retracted. In addition, the inclination means that the paddle part 31 is inclined when viewed from the horizontal / vertical direction, the refraction means that the paddle part 31 is refracted when viewed from the vertical direction, and the retreat means that the paddle part 31 is bent. The one that is curved.
[0014]
In the embodiment of FIG. 1, the processing liquid is rotated from the side portion 31a of the conical bottom paddle portion 31 by the paddle portion 31 to the inner wall surface 7a of the tank bottom portion 7 by rotating the stirring shaft 8 with a driving source (not shown) outside the vessel. Is pushed perpendicularly to the tank, flows downward along the inclined surface of the tank inner wall 7a, rises from the tip 7b of the tank bottom along the axis 8 near the agitation shaft 8, Then, it descends again along the inner wall of the tank, and as a result, the treatment liquid repeats good circulation in the tank and is uniformly stirred, and does not stay at the bottom of the tank as in the prior art.
[0015]
FIG. 3 is a side view of a vertical stirring apparatus according to another embodiment of the present invention. In this figure, the outer shell case 10 is shown in phantom for clarity. The agitation tank 32 has a tank case 10 composed of a straight body part 6, an inverted conical tank bottom part 7, and a lid body 13 that closes the upper part of the straight body part 6. A stirring shaft (rotating shaft) 8 extending through the lid 13 is provided. The stirring shaft 8 protruding upward from the lid body 13 is connected to the output shafts of the electric motor 9 and the speed reducer 18 mounted on the upper portion of the lid body, and is rotationally driven by the urging force of the electric motor 9. A heat transfer coil 11 is installed in the vicinity of the inner wall of the tank case 10 from the straight body 6 to the tank bottom 7 via an appropriate coil support 12. In the illustrated example, the coil 11 is double, but it may be single or multiple. A baffle plate is provided on the inner wall of the tank case 10 as necessary, but this baffle plate may be shared by the coil support 12 as in the illustrated embodiment. The case 10 is provided with a nozzle 14 for passing cooling water or a heat medium through the coil 11.
[0016]
The agitation shaft 8 is pivotally supported by a bottom plate 15 of the tank bottom 7 and a lid 13 at the upper part of the tank, and a lattice blade 3 described later is provided on the outer side of the agitation shaft 8 at a position corresponding to the straight body 6. A conical bottom paddle portion 31 having a large lateral projection area is attached to the stirring shaft 8 at a position corresponding to the tank bottom portion 7. The stirring blade structure of this embodiment is composed of a conical bottom paddle portion 31 at the tank bottom portion 7 and a lattice blade portion 3 at the tank straight body portion 6. The conical bottom paddle part 31 has a lower side part 31a formed at an acute angle so as to follow the inverted conical shape of the tank bottom part 7 as shown in the drawing, and has a vertical outer part 31c near the upper end. The paddle part 31 may be inclined, refracted, or retracted as described with reference to FIG. In the case where the lattice blade part 3 and the conical bottom paddle part 31 are two blades in which the number of blades is aligned in the diameter direction, the positions of the vertical grid 1 of the lattice blade part 3 and the blades of the paddle part 31 are circumferential. Alternatively, they may be shifted from each other by 90 °.
[0017]
The lattice wing 3 attached to the upper stirring shaft 8 adjacent to the conical bottom paddle 31 is provided with a plurality of horizontal arms 2 attached to the stirring shaft 8 and the tip of the horizontal arm 2 and stirred. It has a vertical grid 1 extending parallel to the axis 8. With reference to FIG. 3 and FIG. 4 (A), (B), FIG. 5 (A), (B), the outermost edge 1a of the vertical grid 1 in the outer end of the horizontal arm 2 and the center of the stirring shaft 8 The distance L is larger than the one-side maximum width dimension W (FIG. 3) of the lower large paddle portion 31. Further, the vertical grid 1 as a whole has a wide upper portion and a lower lower portion. In this case, a configuration in which the inside of the lower part is cut into one step as shown in FIG. 3, or a mode in which the inside is cut out in multiple steps as shown in FIG. As shown in FIG. 5B, the inner side may be continuously cut from the upper part toward the lower part so that the lower width becomes narrower.
[0018]
One or more intermediate vertical grids 4 are provided on the horizontal arm 2 between the stirring shaft 8 and the vertical grid 1 at the outer end of the horizontal arm. The vertical grid 1 at the outer end of the arm may be attached to the liquid flow as shown in FIG. 4 (A) or in a retracted form as shown in FIG. The arrows shown in FIGS. 2A and 2B indicate the rotation direction of the stirring shaft 8.
[0019]
FIG. 6 is a side view schematically showing the flow of the liquid during operation of the stirring tank when the tank is viewed from the lateral direction in the embodiment shown in FIG. As described above, since the vertical grid 1 is wide at the top and narrow at the bottom, a downward flow 16 is generated in the vicinity of the inner wall surface of the tank body 6. Since the side of the lower large paddle part 31 runs along the wall surface of the conical tank bottom 7 from near the upper part to the lower part thereof, the flow 17 toward the tank bottom wall is generated here, and the center of the paddle 31 Then, the liquid is sent upward from the tank bottom (reference numeral 19). By combining the downward flow 16 on the wall surface side of the straight body portion and the action of the lower large paddle portion 31 sucking up the liquid in the tank bottom 7 without interfering with each other, a so-called one-stroke circulation flow (continuous sub-circulation flow) ), And a uniform mixing time and a uniform flow rate are provided throughout the tank.
[0020]
In the present invention, since the bottom paddle portion 31 having a large projected area is installed below the lattice blade portion 3, the shape of the bottom portion of the stirring tank has a half apex angle of 60 due to the action of sucking up the liquid at the bottom of the tank by the large blade. Even when it has an acute angle of less than 0 °, uniform mixing can be realized without causing liquid retention at the tip of the tank bottom.
[0021]
Furthermore, the tank bottom has a conical shape with a half apex angle of 60 ° or less, and a tank shape with a high liquid depth (ratio L / D> 1.5 between the liquid depth L from the tank bottom to the liquid surface and the tank inner diameter D). Even in this case, the range of the liquid volume that can be operated is wide, and it is possible to cope with a liquid volume that is 1/200 of the maximum liquid volume. That is, when the liquid amount of the operation is large and the liquid amount fluctuation is large so that it finally increases up to 200 when the initial amount is 1, what has conventionally been used by combining two types of large and small tanks is used in the present invention. Can be handled with one tank.
[0022]
In the case of a stirring tank with a coil, if the outer diameter of the vertical grid 1 of the upper lattice blade portion is set to 0.7 or more with respect to the winding diameter dc of the inner coil 11 in the present invention, As a result, the flow velocity near the heat transfer jacket and the coil is significantly higher than the conventional stirring blade, and as a result, high heat transfer performance can be realized.
[0023]
【The invention's effect】
As described above, according to the present invention, the heat transfer that extends radially from the agitation shaft at the bottom of the agitation tank and along the vicinity of the inner wall of the bottom of the conical bottom of the agitation tank, according to the present invention. Since the conical bottom paddle portion having the outer shape along the coil for use and having a large area is provided, it is possible to perform a good agitation treatment without generating a retention portion of the treatment liquid at the bottom of the tank. In the case where another lattice wing is formed on the conical bottom paddle, the width of the vertical grid of the lattice wing is made wider at the top and narrow at the bottom, and more vertically than the lower large paddle. Since the outermost edge of the grid is made larger than the outer diameter of the paddle part, a downward liquid flow is generated along the tank wall surface in the straight body part of the tank, whereas in the tank bottom part of the conical bottom, By drawing up the liquid, it is possible to form a one-stroke circulation flow with the wall surface of the tank facing downward, using an acute conical bottom with a half apex angle of 60 ° or less , and the inner wall of the bottom of the conical bottom shape There is an effect that it is possible to shorten the upper and lower uniform mixing time in the stirring tank in which the heat transfer coil is arranged along the vicinity, to equalize the flow velocity in the upper and lower directions, and to shorten the heat transfer time.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view of a vertical stirring apparatus when a stirring blade structure having a conical bottom paddle portion according to one embodiment of the present invention is applied to a conical bottom stirring tank.
FIG. 2 is a plan sectional view taken along line AA in FIG.
FIG. 3 is a side view of a vertical stirring apparatus according to another embodiment of the present invention.
FIG. 4 is a plan view when the vertical grid according to the embodiment of the present invention is attached to the horizontal arm while being inclined or retracted.
FIG. 5 is a front view showing an example in which the width of a vertical grid is changed according to an embodiment of the present invention.
6 is a side view schematically showing the flow of the liquid during operation of the stirring tank in the embodiment shown in FIG. 3. FIG.
FIG. 7 is a cross-sectional view of a conventional stirring device using two-stage turbine blades.
FIG. 8 is a schematic view of a conventional stirring device using a discharge type single-stage blade.
FIG. 9 is a view showing a state in which upper and lower liquids are separated by a conventional stirring device using two-stage blades.
FIG. 10 is a view showing a state in which a liquid retention portion is formed at the bottom of a conventional conical bottom type agitation tank.
FIG. 11 is a view showing a state in which a liquid retaining portion is formed at the bottom of a conventional conical bottom type agitation tank.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vertical grid 2 Horizontal arm 3 Lattice blade part 6 Straight body part 7 Tank bottom part 8 Stirring shaft 9 Electric motor 10 Tank case 11 Coil 12 Coil support 31 Conical bottom paddle part 32 Stirrer tank

Claims (2)

An agitating tank whose bottom is formed in an acute conical shape with a half apex angle of 60 ° or less, a heat transfer coil installed along the vicinity of the inner wall of the conical bottom-shaped bottom of the agitating tank, and the center of the agitating tank and a rotating shaft that is driven to rotate from Sogai, in vertical stirring device having a stirring blade attached to said rotary shaft, said stirring blades are arranged in the bottom position of the agitating tank from Rutotomoni said rotary shaft A stirrer blade structure for a vertical stirrer having a conical bottom paddle portion that extends in a radial direction and has an outer shape along the heat transfer coil installed at a conical bottom-shaped bottom portion of the stirring tank. The said stirring blade has the lattice blade part which combined the vertical grid and horizontal arm of the outer diameter larger than the outer diameter of this paddle part above the said conical bottom paddle part. The stirring blade structure of the described vertical stirring apparatus.

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