JP2816963B2 - Stirrer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stirrer for agitation for mixing, dissolving, crystallization, reaction and the like. 2. Description of the Related Art Conventionally, (A) paddle blades (flat blade blades), inclined blade blades, and right-angle turbine blades are often used as stirring blades of a stirrer in one or more stages. In the stirrer using these stirring blades, by increasing the blade rotation speed and increasing the flow rate of the liquid discharged in the radial direction from the outer end of the blade, the liquid collides with the tank wall as shown in FIG. A circulating flow that goes up and down and returns back to the wings is generated to mix in the vessel. (B) Spiral blades and spiral ribbon blades are often used for high viscosity liquids. In addition, a horseshoe wing or an anchor wing is used for (C) a liquid containing a high-viscosity liquid or a solid that tends to settle at the bottom of the tank. [0003] Further, (D) a wound wound blade is often used for dissolving a solid in a liquid. (B), (C),
In the stirrer using the stirring blade of (D), the gap between the outer end of the blade and the tank is reduced to prevent adhesion to the tank wall, to move the liquid, and to shear and scrape the liquid by the blade so that the inside of the tank is reduced. To achieve other purposes. In addition, these stirrers are used at a relatively low blade rotation speed. [0004] When the conventional stirring blade of (A) is used in a single-stage form as shown in FIG. Even if a plurality of baffles reaching the upper part are arranged at intervals, the mixing time is considerably long while requiring a large power required for stirring, and the power characteristics and the mixing characteristics are poor. The mixing characteristics during low-speed rotation stirring are even worse. [0005] Even if the stirring blade of (A) is used in a multi-stage form,
There is a disadvantage that the liquid exchange between the stages is small and the mixing characteristics cannot be improved. Further, the conventional stirrers (B) and (C) have a disadvantage that they are not effective for low-viscosity liquids due to their structure. Further, in the conventional stirring blade of (D), since the discharge force of the liquid from the outer end of the blade is very weak and the phenomenon of liquid circulation and movement is unlikely to occur, it is not possible to achieve a complete mixing state in a short time. was there. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and it is an object of the present invention to reduce the power required for stirring and to improve the mixing performance at the time of low-speed stirring (low power required). And A stirrer according to the present invention is provided with a stirring shaft rotatable from the outside of the tank in the center of the stirring tank, and the shaft is provided with a lower end on the bottom wall surface of the stirring tank. A bottom paddle which is disposed in sliding contact with the bottom of the tank is attached, and an upper portion of the stirring shaft above the bottom paddle is composed of an arm portion and a strip extending in a direction perpendicular to the arm portion. In other words, the grid wings are narrowed as the distance from the stirrer is increased, and a baffle plate extending in the axial direction of the stirring shaft is provided on the side wall of the stirring tank. [0008] Another object of the present invention is to provide a stirring shaft rotatable from outside the tank at the center of the stirring tank inside the stirring tank and above the lattice blade via a coupling. Further, on the side wall surface of the stirring tank, a plurality of baffles extending continuously in the axial direction of the stirring shaft from the upper end of the side of the bottom paddle to the upper end of the side of the lattice blade are provided on the side wall surface of the stirring tank at substantially equal intervals. It is characterized by being arranged in. [0009] BRIEF DESCRIPTION by the examples shown in detail in FIGS. 1-8. In the figure, reference numeral 1 denotes a cylindrical stirring tank, and a stirring shaft 2 is provided in the center of the tank 1. The stirring shaft 2 has a coupling 5 having one end supported at the bottom of the tank via a bearing 3 and the other end provided to a drive unit 4 on the top of the tank, which is provided above a lattice blade 6 described later in the stirring tank. Connected through. Reference numeral 7 denotes a bottom paddle having two paddles, which is mounted on the lower end of the stirring shaft 2, and the lower end of which is in sliding contact with the bottom wall surface of the stirring tank 1. Therefore, this bottom paddle 7
The characteristics of both the conventionally known paddle wing, horseshoe-shaped wing, and anchor-type wing (discharge and shearing), that is, the characteristic of discharging the paddle wing in the radial direction, and the characteristics of the horseshoe-type wing and the anchor-type wing It has the characteristics of scraping, scattering and floating kimono. Reference numeral 6 denotes a lattice blade, and a bottom paddle 7 of the stirring shaft 2
It is attached to a higher part. The lattice wing 6 is composed of an arm portion 8 and a strip 9, and the arm portion 8
Is a plate bar-shaped two paddle extending in the tank radial direction, and the strip 9 is a plate bar extending in a direction perpendicular to the arm portion 8, and the interval between the strips 9 becomes narrower as the distance from the stirring shaft 2 increases. For this reason, the lattice blade 6 has a characteristic that, when rotating, the liquid is sheared and fragmented at the end of each component, and the fragmented liquid is mixed by a minute vortex generated on the rear side of each component. ing. The strip 9
Are combined so as to extend over the entire arm portion 8 ( FIG. 1 ) and are formed in a lattice shape. Reference numeral 10 denotes a flat baffle plate, which is formed of one continuous flat plate extending from the upper end of the side of the bottom paddle 7 to the upper end of the side of the lattice blade 6 on the side wall surface of the stirring tank 1. One or a plurality of these are arranged on the side wall surface of the stirring tank 1 or at substantially equal intervals in the circumferential direction. That is, this baffle plate 10
The liquid discharged from the bottom paddle 7 is circularly moved continuously from the upper end of the side of the bottom paddle on the side wall surface of the stirring tank 1 to the upper end of the side of the lattice blade 6 in the axial direction of the stirring shaft 2. And a characteristic of changing the flow to an axial flow and ascending to the upper portion of the stirring tank 1. Although an example has been described in which the driving device 4 for driving the stirring shaft 2 from outside the tank is provided at the top of the tank, the driving device 4 may be provided at the bottom of the tank. With this stirrer, attention operations (mixing, dissolution, various reactions, etc.) are performed during the stirring operation.
The component ratio is set according to the required capacity. The main operation is as follows. When the lattice blade 6 and the bottom paddle 7 are rotated, the liquid filled in the stirring tank 1 is discharged in the radial direction while being prevented from adhering to the bottom wall of the tank by the bottom paddle 7, and is discharged to the side wall of the tank. At the same time as the collision occurs, the circular motion is changed to linear motion (axial flow of the stirring shaft) by the baffle plate 10 and is raised to the upper part of the tank. The wing 6 moves (flows) downward from near the uppermost arm portion 8 of the wing 6 and returns to the bottom paddle 7. In such a large circulation flow, the descending liquid is sheared and fragmented by the arm portion 8 and the strip 9 of the lattice wing 6 disposed above the bottom paddle 7, and the fragmented liquid is combined with the arm portion 8. The fine vortex generated behind the strip 9 is swirled and mixed. FIGS. 4 and 5 illustrate the above operation. As shown in FIG . 4 , the bottom paddle 7 is
Unlike the conventional paddle blades, the paddle blades are slidably disposed on the bottom of the stirring tank 1 to have both functions as a paddle blade, a horseshoe blade, and an anchor blade. Further, as shown in FIG. 5 , the baffle plate 10 has an action of promoting the generation of the liquid discharged from the bottom paddle 7 to the tank side wall so that the liquid does not move circularly but flows upward. Also, the arm portion 8 of the lattice wing 6
The strip 9 has a function of subdividing and mixing the liquid circulating in the tank by the action of the bottom paddle 7 and the baffle plate 10 in the descending process. At this time, since the interval between the strips 9 at the center of the tank (near the stirring shaft) is wide, the lowering of the circulating liquid is not hindered. In general, the coefficients indicating the characteristics and performance of the blade in the stirring tank include the number of mixing starts and the number of circulations of how many times the liquid discharged from the outer end of the blade circulates in the stirring tank to complete the mixing. Although the comparison test results show that the paddle wings (without baffle plate) are 4 to 7 times and the spiral ribbon wings are 2 times, whereas the one of the present invention (with baffle plate) has a component ratio of Although there was a little width, the number was 1 to 1.3 times. As a representation of the mixing characteristics of the blades in the stirring tank
N. Shown in FIG . there is a θ _M ~R _e curve. In the figure, n. θ _M
Is the complete mixing time θ _M (sec) and the blade rotation speed n (1 / s)
ec) is a value peculiar to the blade multiplied by ec) and is referred to as mixing time, and is an index indicating the mixing performance of the liquid by the blade (including the tank conditions). R _e is a measure of how disordered state of the liquid by the blades (including the bath conditions.), Is said to Reinoizu ^{number, n · d 2 · ρ /} μ
It is represented by Here, n: blade rotation speed (1 / sec),
d: blade diameter (m), ρ: liquid density (kg / m ³ ), μ: liquid viscosity (kg / m · sec). Further, there is an N _{p to} R _e curve shown in FIG. 7 as a representation of the power performance of the blade in the stirring tank. N _p in the figure is a indicator of the power performance of the liquid by the blades (bath conditions including.), Is said power number, represented by ^{P · gc / ρ · n 3} · d 5. Here, P: power (kgm / sec, gc: unit conversion coefficient, ρ: liquid density (kg / m ³ ), n: blade rotation speed (1
/ Sec), d: blade diameter (m). [0019] The n · θ _M ~R _e curve and _N p to R _e curve, D (So径) = 1m, d = 0.5m, ρ = 1000k
g / m ³ . Using these curves, μ = 0.5 kg / m · sec (= 500 c.
p. ), N = 1r. p. s and R _e = 500, the mixing time n · θM is less than that of the present invention (H / D =
(At 1.0), the value a at point A = 16 and the value c at point C in the prior art are c = 80. Therefore, the present invention requires only 1/5 of the mixing time compared to the prior art, and is high even when n = 1 It can be seen that there is mixing ability. The power number _{N p,} the present invention (H / D = 1.0
), The value e at the point E = 5, and the value g at the point G = 8 in the related art.
Since it is, when obtaining the power value required to produce the state of the _R e = 500 with ^{P = Np · (ρ · n} 3 · d 5) / gc, in the present invention 15.94, in the conventional 25. 51, which indicates that the present invention requires 1 / 1.6 of the power required for stirring as compared with the prior art. Further, the solution before mixing is mixed with the same μ = 1/100
0 kg / m · sec (1 cp), and the mixed solution was μ =
0.5 kg / m · sec (500 cp)
The mixing time n · θ _M conventionally changes from the _Co point to the C point as the viscosity increases, and the change amount C- _Co of the value increases to deteriorate the mixing performance. In the invention (when H / D = 1.3), the point changes from point _{Bo to} point B, and the amount of change b- _bo of the value becomes almost zero. It can be seen that there is stable mixing characteristics until the end (high-viscosity liquid) and the product yield is good as a reaction tank efficiently. Further, FIG. 8 shows the same safe mixing time θ.
A comparison between the conventional example and the example of the present invention for the required power corresponding to _M (sec) is shown. According to this, 2000 c.
p. Of 1c. p. It can be seen that the mixture of the present invention is significantly smaller than the conventional mixture. In other words, the present invention can obtain the same performance as the conventional one with small power. The present invention has the above-described structure and has the following effects. (1) good mixing properties over a wide range relative to the wing rotation speed is low Reynolds number because there is good mixing capability with the value R _e. (2) Since the number of circulations is very small, the time (mixing time) until the mixture is completely mixed is short. (3) Since the mixing characteristics at the time of low-speed rotation stirring are high, mild stirring can be performed. (4) The power required for stirring is small, and performance equivalent to that of the related art can be obtained. (5) Since it has stable mixing characteristics from low viscosity liquid to high viscosity liquid, it is effective as a reaction tank. (6) Due to the structure of the lattice blade, the mixing characteristics are stable against a change in the liquid level.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front sectional view showing a first embodiment of the present invention. FIG. 2 shows a first embodiment of the present invention, in which II-II
FIG. FIG. 3 shows a first embodiment of the present invention, and is similar to III-I.
II sectional drawing. FIG. 4 is a diagram illustrating the operation of the present invention. FIG. 5 is a diagram illustrating the operation of the present invention. [6] n · θ _M ~R _e diagram. FIG. 7 is an N _{p to} R _e diagram. [Figure 8] θ _M ~P _v diagram. FIG. 9 is a schematic diagram of a conventional stirrer using paddle blades. [Description of Signs] 1 Stirring tank 2 Stirring shaft 3 Bearing 4 Drive unit 5 Coupling 6 Lattice blade 7 Bottom paddle 8 Arm part 9 Strip 10 Baffle plate

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Seiji Yoshiki               1501 Imaizaie, Toyo City, Ehime Prefecture Sumitomo Heavy Industries               Machinery Co., Ltd.Toyo Factory (72) Inventor Masafumi Kuratsu               1501 Imaizaie, Toyo City, Ehime Prefecture Sumitomo Heavy Industries               Machinery Co., Ltd.Toyo Factory                (56) References JP-B-44-13151 (JP, B1)                 "Chemical engineering"               (Vol. 11 No. 9 1966               73-74 Chemical Industry Co., Ltd.)                 Yoshinori Oyama "Chemical Engineering ▲ II ▲"               P. 183-186 1965 Iwanami Shoten Co., Ltd.                 "Ullmanns Encyklo               radie des technisc               hen Chemie "(4th edition No.               Volume 2 (260-261 1972)                 "Mixing in the Ch               electronic Industry "               (Vol.5 P.306-308 1965)

Claims (1)

(57) [Claims] 1) A stirring shaft rotatable from the outside of the tank is provided at the center of the stirring tank, and the lower end of the stirring shaft is slidably contacted with the bottom wall surface of the stirring tank. A bottom paddle made of a wide flat plate to be provided is attached, and an arm portion and a strip extending in a direction perpendicular to the arm portion are provided above the bottom paddle of the stirring shaft, and the distance between the strips is kept away from the stirring shaft. A stirrer comprising a lattice blade narrowed in accordance with (1) and a baffle plate extending in the axial direction of the stirring shaft on the side wall surface of the stirring tank. 2) A stirrer shaft rotatable from outside the stirrer at the center of the stirrer inside the stirrer and above the lattice blade via a coupling so as to be connectable and separable. The stirrer according to claim 1. 3) On the side wall surface of the stirring tank, a plurality of baffles extending continuously in the axial direction of the stirring shaft from the upper end of the side of the bottom paddle to the upper end of the side of the lattice blade are provided on the side wall surface of the stirring tank at substantially equal intervals. The stirrer according to claim 1 or 2, wherein the stirrer is disposed in a stirrer.