JPH11151432A - Agitating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a gas absorption rate from a gas liq. interface by executing agitation and mixing by allowing an lower part of a helical ribbon balde to exist at a liq. phase and an upper part at a gas phase in the agitating device in which an agitating shaft to which plural helical ribbon blades are fixed is disposed vertically in an agitating tank. SOLUTION: In the helical ribbon balde 4 of the agitating device, its bottom end part is fixed to the agitating shaft 1 by interposing a supporting bar 2, when the lower part of the helical ribbon balde 4 is disposed so that it exists at the liq. phase 7 under the gas liq. interface 6 and the upper part is disposed so that it exists at the gas phase 8 above the gas liq. interface 6. A ratio h2 /h of a height h2 of the part existing at the gas phase 8 of the helical ribbon balde 4 to the height (h) of a total height of the helical ribbon balde 4 is set in a range of 0.05-0.5 preferably. A rotating direction of the helical ribbon balde 4 is the direction in which the liq. is transported upward by the helical ribbon balde 4 preferably, moreover, gas absorption effect is accelerated by imparting a incline angle of 5-45 deg. to the helical ribbon balde 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stirrer suitable for stirring a liquid having a large range of changing viscosity with gas absorption from a gas-liquid interface in a stirring tank.

[0002]

2. Description of the Related Art A stirrer in which gas is absorbed from a gas-liquid interface in a stirring tank is generally provided with a baffle in order to improve the gas absorption speed from the gas-liquid interface. Baffles can be used for low-viscosity fluids, but the gas-liquid interface is not efficiently updated for liquids with medium viscosities of about several thousand cP and high viscosities higher than that, so the gas absorption rate is extremely high. Was late. In addition, there is also a problem that a staying portion due to the baffle is likely to exist. For this reason, for example, in stirring involving a polymerization reaction,
There was a problem that a polymer having a wide molecular weight distribution was formed.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, improve the gas absorption rate from the gas-liquid interface, and stir for uniform stirring and mixing in a stirring tank. In providing the equipment.

[0004]

According to the present invention, there is provided a stirring apparatus having a stirring shaft having one or more helical ribbon blades fixed thereto and vertically installed in a stirring tank. In addition, there is provided a stirrer characterized in that an upper part is present in a gas phase part and is stirred and mixed.

[0005] Further, the present invention provides the above stirring device, wherein a ratio of a height of a portion existing in a gas phase portion of the helical ribbon blade to a total height of the helical ribbon blade is 0.05 to 0.5. Further, the present invention provides the above stirrer, wherein in a vertical cross section of the helical ribbon blade, an inclination angle from the stirring axis of the helical ribbon blade to a stirring tank wall with respect to a direction perpendicular to the stirring axis is 5 to 45 degrees. Further, the present invention provides the above stirring device, wherein the helical ribbon blade has a scraper, and the scraper is provided along the outer periphery of the helical ribbon blade or parallel to the stirring axis.

[0006]

FIG. 1 shows an example of a stirring device according to the present invention. As shown in FIG. 1, the helical ribbon blade 4 is installed so that the lower part is present in the liquid phase part 7 below the gas-liquid interface 6 and the upper part is in the gas phase part 8 above the gas-liquid interface 6.

[0007] The helical ribbon blade 4 is attached to the stirring shaft 1 via the support rod 2. In the example of FIG. 1, two helical ribbon blades 4 are provided, but a single helical ribbon blade or three or more helical ribbon blades may be provided. Usually, two or one helical ribbon blades are preferred.

In FIG. 1, D is the diameter of the stirring tank, d is the blade diameter of the helical ribbon blade, h is the blade height of the helical ribbon blade, h ₁
The blade pitch of the helical ribbon blade, h ₂ is the helical ribbon blade part existing gas phase height, d ₁ denotes the wingspan of the helical ribbon impeller.

The lower end of the helical ribbon blade 4 is fixed to the stirring shaft 1 via the support rod 2. In general, for example, the helical ribbon blade 4 is used as a measure against the movement of the stirring blade due to scale-up of the stirring device. It can be fixed to the stirring shaft at a plurality of positions, for example, by providing a support bar also on the upper part.

[0010] In the present invention, the helical ribbon blade is installed so that the upper portion is present in the gas phase. The ratio h ₂ / h of the height h ₂ of the portion present in the gas phase portion of the helical ribbon blade to the total height h of the helical ribbon blade is 0.05 to 0.5 in order to increase the gas-liquid contact area. Preferably, 0.0
8-0.4 is particularly preferred. As h ₂ / h, agitation, it is preferable to use the value in the mixture without rest.
The value in this state is preferable for a liquid having a large viscosity range that changes even during stirring and mixing, and has a good stirring effect.

In the present invention, the rotation direction of the helical ribbon blade is preferably such that the liquid is transported upward by the helical ribbon blade. By giving the helical ribbon blade an inclination angle from the stirring shaft to the stirring tank wall, the effect of gas absorption is further promoted.

FIG. 2 shows a helical ribbon blade having an inclined angle. The inclination angle (θ) is the inclination angle from the stirring axis of the helical ribbon blade to the stirring tank wall with respect to the direction perpendicular to the stirring axis in the vertical cross section of the helical ribbon blade. When the inclination angle θ of the helical ribbon blade is 5 to 45 degrees, the effect of gas absorption is high.

By rotating the helical ribbon blade having an inclined angle in a direction to lift up the liquid, the upward transfer of the liquid at the gas-liquid interface and the drop of the lifted liquid, that is, the dripping of the liquid, is caused. It has the effect of improving the contact.

FIG. 1 shows a case where the scraper 3 is installed along the outer periphery of the wing, but the scraper 3 can be used without installing the scraper. As shown in FIG. 3, a scraper can be installed in parallel with the stirring axis and in contact with the stirring tank wall.

Since the scraper is pressed and bent, the scraper must be made of resin because it is free from damage to the stirring tank body due to abrasion on the stirring tank wall, and because it is lightweight and easy to attach and detach. Is preferred. Particularly, it is preferably made of a fluororesin, for example, made of polytetrafluoroethylene, because of its heat resistance, chemical resistance, and easy removal of the attached scale.

The ratio h ₁ / d of the blade pitch h ₁ of the helical ribbon blade to the blade diameter d of the helical ribbon blade is 0.5 to 0.5.
2.0 is preferred. If it is too small, the agitation power increases, and if it is too large, the transporting force of the liquid having a medium viscosity or more above the helical ribbon blade decreases. Wing width d of helical ribbon wing
_The ratio d ₁ / d to the blade diameter d of ₁ is preferably in the range of 0.09 to 0.20 in view of the balance between the stirring power and the conveying force of the liquid having a medium viscosity or higher in the upward direction of the helical ribbon blade.
In order to shorten the residence time between the helical ribbon blade and the stirring tank wall, the ratio d / D of the blade diameter d of the helical ribbon blade to the stirring tank diameter D is preferably in the range of 0.9 to 0.98.

In the present invention, the ratio h ₂ / h, the inclination angle θ of the helical ribbon blade, the installation method of the scraper, the ratio h ₁
/ D and the ratio d / D can be variously combined, and liquids having various viscosities and various reaction tank volumes can be handled by combination of optimal conditions. Also, the number of helical ribbon turns,
By optimizing the width of the helical ribbon blade, the gas absorption speed can be further improved.

The stirring apparatus of the present invention is particularly suitable as a polymerization reactor for polymerizing monomers to produce a polymer.
The present invention can be applied to the production of polymers of various monomers such as olefins, vinyl chloride and methacrylate, as well as the polymers of the fluorine-containing monomers shown in Examples. In particular, it is an optimal stirring device for producing homopolymers and copolymers of fluorine-containing monomers such as tetrafluoroethylene, chlorotrifluoroethylene, vinylidene fluoride, and hexafluoropropene.

[0019]

The present invention will be described below in more detail with reference to Examples 1 to 14, but the present invention is not limited thereto.

[Example 1 (embodiment)] In two rows, the blade diameter d is 19
5 mm, wing height h is 187 mm, wing width d ₁ is 20 mm, ratio h ₁ / d is 0.64, helical ribbon blade inclination angle θ
In a stainless steel reaction vessel having a stirring vessel diameter D of 203 mm and a capacity of 10 liters, in which a helical ribbon blade having a winding number of 1.5 and a winding number of 1.5 was installed, copper sulfate (10 ^-4 mol /
l) to which 0.5 ml of an aqueous sodium sulfite solution (0.1 mL) was added.
(12 mol / l), 4 liters were charged, the inside of the reaction vessel was degassed under reduced pressure, and then pressurized to 50 mmHg with oxygen. The h ₂ / h in the stationary state without stirring and mixing was 0.50. At a predetermined stirring number, the oxygen partial pressure drop in the reaction vessel at a liquid temperature of 30 ° C. was measured, and the oxygen absorption rate per unit volume of the reaction solution (unit: 10 ⁻⁶ mol / liter · second) was determined. Table 1 shows the results.

Example 2 (Comparative Example) Copper sulfate (10 ⁻⁴ mol / l) was ^{added to} 0.1 ml of the same reaction vessel and stirring blade as in Example 1.
9 ml of aqueous sodium sulfite solution (0.12 mol
/ L) 7 liters were charged, and the oxygen absorption rate was determined in the same manner as in Example 1. Table 1 shows the results. Stirring, do not mix,
H ₂ / h in the stationary state was 0.

Example 3 (Example) The oxygen absorption rate was measured using the same reaction vessel and stirring blade as in Example 1. Viscosity 2000 with 0.5 ml of copper sulfate (10 ^-4 mol / l) added
cP sodium sulfite syrup aqueous solution (0.12 mol /
l) 4 liters were charged, and the absorption rate was determined in the same manner as in Example 1. Table 1 shows the results. h ₂ / h was 0.50.

Example 4 (Comparative Example) The oxygen absorption rate was measured using the same reaction vessel and stirring blade as in Example 1. Viscosity 2000 with 0.9 ml of copper sulfate (10 ^-4 mol / l) added
cP sodium sulfite aqueous solution of starch syrup (0.12 mol /
l) 7 liters were charged, and the absorption rate was determined in the same manner as in Example 1. Table 1 shows the results. h ₂ / h was 0.

[0024]

[Table 1]

Example 5 (Example) A 10 liter stainless steel reaction vessel was degassed, and 1,1,2,2,3,
3,4,4,5,5,6,6,6-tridecafluorohexane 10.7 kg, (perfluorobutyl) ethylene 15.3 g, tetrafluoroethylene (hereinafter referred to as TFE) 724 g, ethylene 51.0 g, chain 10.7 g of cyclohexane as a transfer agent and a 1% by weight perfluorohexane solution of perfluorobutyl peroxide as a polymerization initiator were charged, and the reaction was started at 65 ° C. The same stirring device as that used in Example 1 was used. H ₂ / h in the stationary state without stirring and mixing at the beginning of the reaction
Was 0.09.

During the reaction, a mixed gas of TFE / ethylene 53/47 (molar ratio) was introduced into the reaction vessel, and the reaction pressure was maintained at 8.1 kg / cm ² . The polymerization initiator was charged intermittently so that the polymerization rate was almost constant, and a total of 100
ml. After 6 hours, a slurry having a solid content of 1.1 kg and a concentration of 130 g / liter (solvent) was obtained. At the beginning of the reaction, the slurry is about 1 cP. After the completion of the reaction, the slurry is estimated to be about 5500
cP.

Example 6 (Comparative Example) In the same manner as in Example 5,
In a similar stirring device, stirring at the start of the reaction, not mixed, h ₂ / h in the still state the reaction was carried out at 0. After 12 hours, a slurry having a solid content of 1.0 kg and a concentration of 108 g / liter (solvent) was obtained. The initial stage of the reaction was about 1 cP, and the slurry after the completion of the reaction was about 5000 cP at the reaction temperature according to the estimation from the stirring power.

[Example 7 (Example)] A stainless steel reactor having an internal volume of 20 liters was degassed, and CF ₂ = CFOCF ₂ C
10.07 kg of FOCF ₃ (CF ₂ ) ₂ SO ₃ F, C
5.73 kg of ClF ₂ CF ₂ CHClF and 2,2′-azobisisobutyronitrile (AIB) as a polymerization initiator
N) was charged at 400 ppm. After introducing TFE into the reaction vessel and dissolving it in the charged monomer and solvent until the saturation solubility was reached, the reaction was started. Reaction temperature is 7
At 0 ° C., the reaction pressure was maintained at 11.1 kg / cm ² . The stirring rotation speed was 142 rpm.

The stirring device used had a stirring tank diameter D of 250.
mm, having a stirring blade provided with a scraper along the ribbon on two helical ribbon blades, and a blade diameter d of 23 mm.
0 mm, wing height h is 207 mm, wing width d ₁ is 21.8 m
m, the ratio h ₁ / d is 0.90, the inclination angle θ of the helical ribbon blade is 5 degrees, and the number of turns of the helical ribbon blade is 1.0. The h ₂ / h in the stationary state without stirring and mixing at the start of the reaction was 0.26.

After 8 hours, a slurry having a solid content of 2.85 kg and a solid concentration of 16.4% by weight was obtained. At the beginning of the reaction, it was about 1 cP, and after the completion of the reaction, the slurry was found to have a reaction temperature of 16,000 cP according to estimation from power.

Example 8 (Comparative Example) Using the same reactor as in Example 7, a scraper was installed along the ribbon on two helical ribbon blades, the blade diameter d was 230 mm, and the blade height h was 154 m.
m, blade width d ₁ is 21.8 mm, ratio h ₁ / d is 0.6
7. A stirring blade having a helical ribbon blade inclination angle θ of 5 degrees and a helical ribbon blade winding number of 1.0 is used, and h ₂ / h is 0.
The reaction was carried out in the same manner as in Example 7. After 24 hours, a slurry having a solid content of 2.55 kg and a solid concentration of 14.8% by weight was obtained. The initial stage of the reaction was about 1 cP, and the slurry after the completion of the reaction was about 14000 cP at the reaction temperature according to the estimation from the stirring power.

Example 9 (Example) Using the same reactor as in Example 7, a scraper was installed on two helical ribbon blades in parallel with the stirring axis, the blade diameter d was 230 mm, and the blade height h was 179 m.
m, blade width d ₁ is 21.8 mm, ratio h ₁ / d is 0.5
2. Using a stirring blade having a helical ribbon blade inclination angle θ of 5 degrees and a helical ribbon blade winding number of 1.5, with h ₂ / h of 0.14, a reaction was carried out in the same manner as in Example 7. . 10.
After 5 hours, a slurry having a solid content of 2.68 kg and a solid concentration of 15.5% by weight was obtained. The initial stage of the reaction was 1 cP, and the slurry after the completion of the reaction was approximately 15000 cP at the reaction temperature according to the estimation from the stirring power.

Example 10 (Example) Using the same reactor as in Example 7, a scraper was installed along two helical ribbon blades along the helical ribbon blade, the blade diameter d was 230 mm, the blade height h was 207 mm, Wing width d ₁ is 21.8 mm, ratio h ₁ /
d is 0.90, the number of turns of the helical ribbon blade is 1.0, and the inclination angle θ of the helical ribbon blade is 20 degrees.
The reaction was carried out in the same manner as in Example 7, except that h ₂ / h was 0.26. After 7 hours, the solid content is 2.85 kg and the solid content concentration is 16.
A 4% by weight slurry was obtained. Initial reaction is about 1 cP
After the completion of the reaction, the slurry had a reaction temperature of about 16000 cP, as estimated from the stirring power.

Example 11 (Comparative Example) Using the same reactor as in Example 7, a scraper was installed along two ribbons on a helical ribbon blade, the blade diameter d was 230 mm, and the blade height h was 154.
mm, wing width d ₁ is 21.8 mm, ratio h ₁ / d is 0.6
7. Using a stirring blade having a helical ribbon blade winding number of 1.0 and a helical ribbon blade inclination angle θ of 20 degrees, a reaction was carried out in the same manner as in Example 7, except that h ₂ / h was 0. After 23.5 hours, a slurry having a solid content of 2.52 kg and a solid content concentration of 14.7% by weight was obtained. The initial stage of the reaction was about 1 cP, and the slurry after the completion of the reaction was about 14000 cP at the reaction temperature according to the estimation from the stirring power.

Example 12 (Example) Using the same reactor as in Example 7, a scraper was installed in parallel with the stirring shaft on two helical ribbon blades, the blade diameter d was 230 mm, and the blade height h was 179.
mm, wing width d ₁ is 21.8 mm, ratio h ₁ / d is 0.5
2. Using a stirring blade having a helical ribbon blade winding number of 1.5 and a helical ribbon blade inclination angle θ of 20 °, h ₂ / h was 0.14, and the reaction was carried out in the same manner as in Example 7. . 9.5
After an hour, the solid content was 2.71 kg, and the solid content was 15.
A 7% by weight slurry was obtained. Initial reaction is 1cP,
After the completion of the reaction, the slurry had a reaction temperature of about 15000 cP as estimated from the stirring power.

Example 13 (Example) Using the same reactor as in Example 7, a scraper was installed along the ribbon on two helical ribbon blades, the blade diameter d was 230 mm, and the blade height h was 207.
mm, the blade width d ₁ is 21.8 mm, and the ratio h ₁ / d is 0.9.
0, the number of turns of the helical ribbon blade is 1.0, using a stirring blade tilt angle θ is 30 degrees of the helical ribbon blade, h ₂ / h is 0.26, the reaction was carried out in a similar manner to Example 7 . After 7 hours, a slurry having a solid content of 2.95 kg and a solid concentration of 16.9% by weight was obtained. The initial stage of the reaction was about 1 cP, and the slurry after completion of the reaction was about 17000 cP at the reaction temperature according to estimation from the stirring power.

Example 14 (Comparative Example) Using the same reactor as in Example 7, a scraper was installed in parallel with the stirring shaft on two helical ribbon blades, the blade diameter d was 230 mm, and the blade height h was 179.
mm, wing width d ₁ is 21.8 mm, ratio h ₁ / d is 0.5
2. Using a stirring blade having a helical ribbon blade winding number of 1.5 and a helical ribbon blade inclination of 50 degrees, and h ₂ / h of 0.1
In 4, the reaction was carried out in the same manner as in Example 7. After 7 hours, a slurry having a solid content of 2.62 kg and a solid content concentration of 15.2% by weight was obtained. The initial stage of the reaction was about 1 cP, and the slurry after the completion of the reaction was about 15000 cP at the reaction temperature according to the estimation from the stirring power.

[0038]

According to the present invention, the helical ribbon has a liquid phase portion, and the upper portion of the helical ribbon blade is in the gas phase. The ratio to the total wing height is 0.05 to 0.5
By being installed, stirring, and mixing,
The upward transfer of the liquid at the gas-liquid interface and the drop of the picked-up liquid, that is, the liquid dripping have an effect of improving the gas-liquid contact.

In the case where gas is absorbed from the gas-liquid interface, the liquid having a low viscosity disturbs the gas-liquid interface, and the liquid having a medium viscosity or more efficiently disperses the fluid carried by the helical ribbon at the gas-liquid interface. Renewal can promote gas absorption rate.

[Brief description of the drawings]

FIG. 1 is a front view of an example of the stirring device of the present invention.

FIG. 2 is a vertical sectional view of an example of a helical ribbon blade according to the present invention.

FIG. 3 is a front view of another example of the stirring device of the present invention.

[Explanation of symbols]

 1: stirring shaft 2: support rod 3: scraper 4: helical ribbon blade 5: frame 6: gas-liquid interface 7: stirring liquid phase 8: stirring gas phase

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nobumoto Kasahara 1150 Hazawa-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Inside (72) Inventor Jun Watanabe 1150 Hazawa-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Asahi Glass Co., Ltd. Inside

Claims (4)

[Claims] An agitator having one or more helical ribbon blades fixed to a stirring vessel and having a stirring shaft fixed vertically, wherein a lower portion of the helical ribbon blade is in a liquid phase portion and an upper portion is in a gas phase portion. A stirrer characterized by being present and adapted to be stirred and mixed. 2. The ratio of the height of the portion of the helical ribbon blade present in the gas phase to the total height of the helical ribbon blade is 0.0.
The stirrer according to claim 1, wherein the ratio is 5 to 0.5. 3. The stirring according to claim 1 or 2, wherein in a vertical cross section of the helical ribbon blade, an inclination angle from the stirring axis of the helical ribbon blade to a wall of the stirring tank with respect to a direction perpendicular to the stirring axis is 5 to 45 degrees. apparatus. 4. The helical ribbon wing has a scraper,
4. The stirring device according to claim 1, wherein the scraper is provided along the outer periphery of the helical ribbon blade or parallel to the stirring axis.