JP2021098152A - Gas-liquid mixing device and gas-liquid mixing method - Google Patents

Abstract

To provide a gas-liquid mixing device and a gas-liquid mixing method, used for mixing gas and a liquid substance, capable of mixing the gas and the liquid substance with supplied bubbles efficiently distributed entirely in a mixing tank without increasing mixing power.SOLUTION: A gas-liquid mixing device comprises a mixing tank, a mixer, a baffle plate, and a gas supply pipe. The mixing tank has a shape of a circular column or a polygonal column with a circular bottom plate or a polygonal bottom plate having vertex angles equal to or larger than 90 degrees. An extended section is arranged so that at least a portion thereof is brought into contact with a cyclic flow boundary and/or an area around the same between a cyclic flow generated above a liquid substance in the mixing tank and a mixing flow generated below the cyclic flow. The baffle plate is arranged with a width direction thereof that coincides with a direction from an inner wall of the mixing tank to a center thereof. The gas supply pipe has a gas supply port which is directed toward an inside of the mixing tank. The gas supply port is positioned lower than a mixing blade.SELECTED DRAWING: Figure 2

Description

The present invention relates to a gas-liquid mixing device and a gas-liquid mixing method. More specifically, the present invention relates to a gas-liquid mixing device used for mixing a gas and a liquid material, and a gas-liquid mixing device and a gas-liquid mixing method capable of efficiently dispersing and mixing in the entire stirring tank.

For a chemical reaction in a chemical plant or the like, a mixing device for stirring and mixing liquid substances in a stirring tank using a stirring blade is widely used. In such a mixing device, various studies have been made in order to increase the mixing efficiency of the liquid substance without increasing the stirring power.

For example, in Patent Document 1, a stirring shaft is hung at the center of the stirring tank, a stirring blade is provided at the lower end of the stirring shaft, and the stirring blade is fixed to the bottom of the stirring tank so as to be arranged near the outer side of the stirring blade. A mixing device provided with blades has been proposed. According to the mixing device of Patent Document 1, a flow from the lower side to the upper side occurs near the inner wall surface of the stirring tank, and this flow gathers in the central portion and its vicinity, and the flow from the upper side to the lower side in the central portion and its vicinity. It has been reported that the swirling flow is converted into a radial discharge flow by the blades fixed to the bottom at the bottom thereof, and the mixing efficiency can be improved.

Further, according to Patent Document 1, it is also proposed to provide a baffle plate on the inner wall surface of the stirring tank and to provide an auxiliary stirring device above the stirring blade when dissolving or decomposing a light powder or solid matter. There is. It has also been reported that by using the baffle plate and the auxiliary stirrer in this way, it is possible to form a circulating flow that sends powder or solid matter downward.

Japanese Unexamined Patent Publication No. 2018-027544

By the way, in the gas-liquid mixing device, air bubbles are usually supplied from the lower part of the stirring tank. The bubbles supplied in this way tend to be diffused by the stirring flow of the liquid material. At this time, if a baffle plate is provided inside, the stirring flow tends to rise in the stirring tank, but when the stirring power is weak, the coalescence progresses too much until such bubbles reach the upper part of the stirring tank. Also, the bubbles do not diffuse sufficiently. When the stirring power is weak as described above, the mixing of the entire stirring tank may not be sufficient.

The present invention has been made in view of the above circumstances, and in a gas-liquid mixing device used for mixing a gas and a liquid substance, the supplied air bubbles can be stirred in a stirring tank without increasing the stirring power. It is an object of the present invention to provide a gas-liquid mixing device and a gas-liquid mixing method capable of efficiently dispersing and mixing the whole of the inside.

When the baffle is provided inside the stirring tank, the stirring flow generated in the lower part of the liquid material in the stirring tank has a rotation direction opposite to that of the circulating flow generated in the upper part of the liquid material in the stirring tank. It may flow. The flow from the inner wall of the stirring tank to the stirring shaft (center of the stirring tank) generated at the boundary of those flows (hereinafter, also referred to as “circulating flow boundary”) may be referred to as “circulating flow boundary flow”. ) May hinder mixing between the liquid material belonging to the circulating flow in the upper part of the stirring tank and the liquid material belonging to the stirring flow in the lower part. In such a case, the inhibition of mixing by the flow at the circulation flow boundary is caused by a part of the auxiliary stirrer including the extending portion extending from the stirring shaft toward the inner wall of the stirring tank to the circulation flow boundary and / or its vicinity. It can be suppressed by arranging it so as to contact the range. Specifically, the present invention provides the following.

(1) The invention according to the first embodiment includes a stirring tank, a stirring machine, a baffle plate, and a gas supply pipe, and the stirring tank is circular or polygonal with all angles of 90 ° or more. It has a tubular shape with a bottom surface and can accommodate liquid matter inside, and the stirrer has a stirring shaft hanging from the upper part of the stirring tank and stirring provided substantially perpendicular to the stirring shaft. It has a blade and an auxiliary stirrer including an extending portion extending from the stirring shaft toward the inner wall of the stirring tank, and the extending portion has at least a part of the liquid material in the stirring tank. The baffle plate is arranged so as to be in contact with the circulation flow boundary existing between the circulation flow generated in the upper part of the above and the stirring flow generated in the lower part thereof and / or a range in the vicinity thereof, and the baffle plate is viewed from above the stirring tank. In this case, the width direction is arranged from the inner wall side of the stirring tank toward the center of the stirring tank, and the gas supply pipe has a gas supply port toward the inside of the stirring tank. The gas supply port is a gas-liquid mixing device arranged below the stirring blade.

(2) The invention according to the second embodiment is a gas-liquid mixing device in which the extending portion has a rod shape in the first invention.

(3) The invention according to the third embodiment is the gas-liquid mixing device having a ring shape in the first or second invention.

(4) The invention according to the fourth embodiment is a gas-liquid mixing device having a plurality of gas supply ports in any one of the first to third inventions.

(5) The invention according to the fifth embodiment is a gas-liquid mixing method in which a gas and a liquid substance are mixed, and has a circular shape or a tubular shape having a polygonal bottom surface having all angles of 90 ° or more. In the stirring tank, when the stirring tank is viewed from above, the liquid material is stored inside the stirring tank in which the baffle plate is arranged so that the width direction is from the inner wall side of the stirring tank toward the center of the stirring tank. Then, when gas is supplied to the stirring tank from the gas supply port of the stirring gas supply pipe and the liquid substance and the gas are mixed by the stirring machine, the stirring shaft and the stirring shaft hanging from the upper part of the stirring tank are used as the stirring machine. The stirring blade is provided perpendicular to the stirring shaft, and an auxiliary stirring tool including an extending portion extending from the stirring shaft toward the inner wall of the stirring tank is provided. At least a part thereof is arranged so as to be in contact with the circulating flow boundary existing between the circulating flow generated in the upper part of the liquid material in the stirring tank and the stirring flow generated in the lower part thereof and / or the vicinity thereof. This is a gas-liquid mixing method in which the mixing is performed by using a gas supply pipe whose gas supply port is arranged below the stirring blade.

According to the present invention, in the gas-liquid mixing device used for mixing a gas and a liquid substance, air bubbles supplied from the lower part of the stirring tank can be efficiently dispersed and mixed in the entire stirring tank.

It is a cross-sectional schematic diagram of the gas-liquid mixing apparatus which concerns on this embodiment. It is a schematic vertical sectional view of the gas-liquid mixing apparatus which concerns on this embodiment. It is a schematic diagram which shows the flow of a liquid substance generated when a liquid substance is stored in a stirring tank provided with a baffle and is stirred. It is a schematic diagram of the attachment device of the auxiliary stirrer. It is a schematic view of the auxiliary stirrer which concerns on this embodiment, (a) is a top view, and (b) is a side view. It is a schematic view of the auxiliary stirrer which concerns on this embodiment, (a) is a top view, and (b) is a side view. It is a schematic view of the auxiliary stirrer which concerns on this embodiment, (a) is a top view, and (b) is a side view. It is a schematic view of the auxiliary stirrer which concerns on this embodiment, (a) is a top view, and (b) is a side view. It is a schematic view of the auxiliary stirrer which concerns on this embodiment, (a) is a top view, and (b) is a side view. It is a schematic view of the auxiliary stirrer which concerns on this embodiment, (a) is a top view, and (b) is a side view. It is a schematic view of the auxiliary stirrer which concerns on this embodiment, (a) is a top view, and (b) is a side view. It is a vertical cross-sectional schematic diagram of the gas-liquid mixing apparatus for demonstrating the calculation method of a circulation flow boundary.

Hereinafter, specific embodiments of the present invention (hereinafter, referred to as “the present embodiment”) will be described in detail. However, the present invention is not limited to the following embodiments, and various modifications can be made without changing the gist of the present invention. In each drawing, the same components may be designated by the same reference numerals, and duplicate description may be omitted.

In the present embodiment, the solid, liquid, and gas (gas) refer to the three states of a substance itself. Liquids are concepts that include (pure) liquids, liquids including gases (including gases introduced from gas supply pipes), solutions and slurries.

≪Gas-liquid mixer≫
The gas-liquid mixing device according to the present embodiment includes a stirring tank, a stirrer, a baffle plate, and a gas supply pipe, and supplies gas to the liquid material contained in the stirring tank to perform gas-liquid mixing. It is something to do.

FIG. 1 is a schematic cross-sectional view of the gas-liquid mixing device according to the present embodiment. Further, FIG. 2 is a schematic vertical cross-sectional view of the gas-liquid mixing device according to the present embodiment. As shown in FIGS. 1 and 2, the gas-liquid mixing device 1 includes a stirring tank 11, a stirring machine 12, a baffle plate 13, and a gas supply pipe 14. The liquid substance L is contained in the stirring tank 11. The stirrer 12 has a stirrer shaft 121, a stirrer blade 122 provided on the stirrer shaft 121, and an auxiliary stirrer 123. The auxiliary stirrer 15 is arranged so that at least a part thereof contacts the circulation flow boundary existing between the circulation flow generated in the upper part of the liquid material L and the stirring flow generated in the lower part and / or a range in the vicinity thereof. It has an extending portion 124. Further, a gas supply port is provided at the tip of the gas supply pipe 14 on the inner side of the stirring tank. The details of the circulating flow, the stirring flow, and the circulating flow boundary will be described later with reference to FIG.

Such a gas-liquid mixing device 1 can be used, for example, to supply a gas to the liquid substance L and dissolve the components in the gas in the liquid substance L to obtain a solution. It can also be used to supply a gas to the liquid L containing the chemical solution to cause a chemical reaction between the chemical solution and the components in the gas to obtain a reaction product. As described above, the gas-liquid mixing device 1 can be used for any application as long as it is intended to mix the gas and the liquid substance L. If necessary, the gas-liquid mixing device 1 may be provided with a supply mechanism for supplying a drug, a solvent, or the like into the stirring tank 11.

FIG. 3 is a schematic view showing the flow of the liquid material generated when the liquid material is stored in a stirring tank provided with a baffle and the liquid material is stirred.

Hereinafter, the formation mechanism of the circulating flow interface B will be described with reference to FIG. The flow from the inner wall of the stirring tank 11 to the stirring shaft 121 (circulating flow interface flow) is provided in the stirring tank 11 for stirring the liquid substance L, supplying gas to the liquid substance L, and in the stirring tank 11. It is generated by the baffle plate 13.

When the stirring blade 122 rotates, a liquid substance is discharged toward the lower part of the stirring tank 11, and a flow due to stirring is generated. Of the flow due to the stirring, the component parallel to the stirring shaft 121 becomes a flow from the stirring blade 122 toward the bottom surface of the stirring tank 11. Further, the component perpendicular to the stirring shaft 121 goes from the stirring blade 122 to the inner wall of the stirring tank 11, and this component is a swirling flow having a component in the rotation direction of the stirring blade 122.

Of the flow due to stirring, the main component toward the bottom surface of the stirring tank 11 collides with the bottom surface of the stirring tank 11 and becomes a flow that directly follows the bottom surface toward the inner wall of the stirring tank 11. Then, when this flow collides with the inner wall, it becomes a flow upward along the inner wall.

Of the flow due to stirring, the component perpendicular to the stirring shaft 121 collides with the inner wall of the stirring tank 11 and then swirls along the inner wall in the rotation direction of the stirring blade. However, since the baffle plate 13 is installed, it collides with the baffle plate 13 and changes the direction of the flow, merges with the component perpendicular to the stirring shaft 121, and becomes an upward flow.

Further, the liquid material in the stirring tank 11 circulates in the stirring tank 11 by stirring by the stirring machine 12. Of the flow due to stirring, the flow becomes an ascending flow along the inner wall of the stirring tank 11, becomes a flow along the circulation flow boundary B, and finally reaches the upper part of the stirring blade 122. From there, this flow becomes a flow toward the stirring shaft 121 again in the stirring tank 11 and is discharged toward the lower part of the stirring tank 11. The liquid material in the stirring tank 11 constantly repeats the above to form a circulating stirring flow S.

On the other hand, the gas supplied from the gas supply pipe 14 becomes bubbles in the liquid material L in the stirring tank 11. Buoyancy is generated in the bubbles due to the difference in density from the surrounding liquid product L. Here, the flow rate due to stirring increases from the stirring blade 122 to the gas supply pipe 14, and from the gas supply pipe 14 to the bottom surface of the stirring tank 11, the inner wall, the circulation flow boundary B, and the vicinity of the stirring shaft 121 of the circulation flow boundary B. It becomes slower and the force to split the bubbles in the flow (so-called shear stress) becomes smaller. In the flow by stirring slowed down in this way, the bubbles coalesce and the bubble diameter gradually increases. The buoyancy generated in a bubble is proportional to the cube of the diameter of the bubble. Also, the drag generated between the bubble and the flow is proportional to the square of the diameter of the bubble. Therefore, when the bubbles become large to some extent, the buoyancy becomes stronger than the drag force acting during the descending flow in the stirring tank 11, and the bubbles float away from the descending flow. The generation of bubbles that float away from the downward flow causes a reaction of the drag of the liquid acting on the bubbles, and the flow around the bubbles becomes an upward flow. Therefore, in the vicinity of the stirring shaft 121, with a specific height of the stirring tank 11 as a boundary, the upper part of the stirring tank 11 becomes an upward flow, and the lower part thereof becomes a downward flow. In this way, a circulating flow C that rotates in the opposite direction to the stirring flow S including the rising flow generated on the stirring shaft 121 is formed above the stirring flow S. In this reverse rotation circulation flow C, the flow flowing to the stirring shaft 121 via the vicinity of the inner wall of the stirring tank 11 is in contact with the flow above the stirring flow C. A circulating flow interface B is formed at a portion where the circulating flow C and the stirring flow S are in contact with each other due to this buoyancy, and a circulating flow interface flow from the stirring tank 11 toward the stirring shaft 121 is generated.

In the gas-liquid mixing device 1 according to the present embodiment, an auxiliary stirrer 123 including an extending portion 124 extending from the stirring shaft 121 toward the inner wall of the stirring tank 11 is provided at the circulation flow interface B, and the stirring shaft is provided. According to the rotation of 121, it is rotated together with the stirring blade 122. As a result, the circulating flow boundary flow is made to collide with the auxiliary stirrer and the flow generated by the auxiliary stirrer 123 to create a flow different from the circulating flow boundary flow, whereby the upper part of the liquid material L in the stirring tank 11 is formed. Can promote mixing between the bottom and the bottom.

Hereinafter, the gas-liquid mixing device 1 will be described in more detail with reference to FIGS. 1 and 2.

[Stirring tank]
The stirring tank 11 is a cylindrical tank (container) having a circular bottom shape or a polygonal bottom surface having all angles of 90 ° or more. At least one end (bottom surface) of the stirring tank 11 is closed, and the liquid substance L can be contained therein. On the one hand, the other end (upper surface) may be open or closed.

The upper surface (when closed) and the lower surface are not limited to those that are flat, respectively, and include a portion having a curvature on the upper surface or the bottom surface in a vertical cross-sectional view cut in the vertical direction, or the upper surface, the bottom surface, and the inner wall. Those including a portion having a curvature between and can be used.

When the bottom surface shape of the stirring tank is a polygon, it is not particularly limited as long as all the angles of the polygon are 90 ° or more, but it is preferably 100 ° or more, more preferably 110 ° or more, and 120 °. It is more preferably ° or more, and particularly preferably 130 ° or more.

As described above, the liquid L is not particularly limited, and a solution-like liquid or a slurry-like liquid in which a solid content is dispersed in a solvent can be used. The chemical solution and the like may include those that contribute to the chemical reaction, as well as a component modifier of the chemical solution, a trace amount of dispersant and a surfactant that do not contribute to the chemical reaction, and the like. Further, the liquid containing the chemical liquid and the like can also include a liquid such as a solvent and a diluting liquid. When a chemical reaction occurs inside this, the type is not particularly limited.

[Stirrer]
The stirrer 12 includes a stirring shaft 121 hanging from the upper part of the stirring tank 11, a stirring blade 122 provided perpendicular to the stirring shaft 121, and a spreading extending from the stirring shaft 12 toward the inner wall of the stirring tank 11. It has an auxiliary stirrer 123 including an existing part. The stirrer 12 has, for example, a motor, and the rotation of the motor is transmitted to the stirring shaft 12 to stir. The stirring shaft 12 rotates as a rotating shaft to stir the liquid material L contained in the stirring tank 11. A stirring flow is generated, and the stirring flow mixes with the gas supplied from the gas supply pipe 14.

The stirring blade 122 is not particularly limited as long as it can generate an axial flow, and specifically, the propeller blade and the paddle blade shown in FIGS. 1 and 2 can be used. Further, as the stirring blade 122, it is preferable to use one composed of two or more stirring blades in order to prevent shaft shake. For example, when a propeller blade is used as the stirring blade 122, the number of blades may be three or more. When a paddle blade is used as the stirring blade 122, the number of blades may be two or more. In any case, the number of blades is preferably 16 or less, for example, but may be 17 or more.

Further, it is preferable that the stirring shaft 121 is arranged so that the center thereof coincides with the center of the cross section of the stirring tank 11 in the cross-sectional view of the stirring tank 11.

[Baffle board]
The baffle plate 13 is arranged in the stirring tank 11, and when the stirring tank 11 is viewed from above, the baffle plate 13 is arranged upright from the inner wall side of the stirring tank 11 toward the center of the stirring tank 11. Is to be done. The flow of the liquid material generated by the stirrer 12 is mainly a flow that swirls in the horizontal direction, but by using the baffle plate 13, the flow in the vertical (vertical) direction can be made stronger. However, when the flow in the vertical (vertical) direction is weak, the stirring flow generated in the lower part of the stirring tank 11 does not reach the upper part, and the rotation direction is opposite to that of the circulating flow generated in the upper part of the stirring tank 11. Flow with. At the boundary between the lower stirring flow and the upper circulating flow (circulating flow boundary), both flows flow from the stirring tank 11 toward the stirring shaft 121 and strengthen each other. In this way, the strong flow in the direction from the stirring tank 11 to the stirring shaft 121 (circulating flow boundary flow) generated at the circulation flow boundary hinders mixing between the upper part and the lower part of the stirring flow tank 11.

Here, the height of the baffle plate 13 means the distance in the longitudinal direction of the stirring tank 11. The width of the baffle plate 13 means the width of the baffle (obstruction plate) in the direction from the inner tank of the stirring tank toward the central axis, and is the horizontal length of the surface of the baffle 13 when the stirring tank 11 is viewed from above. That's right.

The height of the baffle plate 13 is not particularly limited, but it is preferable to use one that is higher than the liquid height of the liquid material, which is the distance from the bottom surface of the stirring tank 11 to the liquid surface. The baffle plate 13 does not have to be arranged in contact with the bottom surface.

As the baffle plate 13, one or a plurality of baffle plates 13 can be used. From the viewpoint of further increasing the stirring efficiency in the stirring tank 11, it is preferable to use a plurality of baffle plates 13. When a plurality of baffle plates 13 are used, it is preferable to arrange them at equal intervals when the stirring tank 11 is viewed from above from the viewpoint of further improving the stirring efficiency in the stirring tank 11.

The baffle plate 13 does not necessarily have to be in contact with the inner wall or bottom of the stirring tank 11, and may be separated from the inner wall or bottom of the stirring tank 11.

[Auxiliary stirrer]
The auxiliary stirrer 123 includes an extending portion 124 extending from the stirring shaft 121 toward the inner wall of the stirring tank 11. Then, at least a part of the extending portion 124 and the flow generated by the rotation of the extending portion 124 of the auxiliary stirrer 123 (effective flow generated in the vicinity range) are generated in the upper part of the liquid material L in the stirring tank. It is arranged so as to be in contact with the circulating flow boundary B and / or the vicinity thereof existing between the circulating flow and the agitated flow generated below it. That is, the auxiliary stirrer 123 has an extending portion 124 extending from at least a portion of the stirring shaft 121 above the stirring blade 22 toward the inner wall of the stirring tank 11.

The bubbles supplied from the gas supply port of the gas supply pipe 14 ride on the flow of the liquid substance L in the stirring tank 11 by stirring, and finally the bubbles are united in the vicinity of the stirring shaft 121. When the buoyancy of the grown bubbles is larger than the drag generated by the flow descending in the stirring tank 11, the flow from the inner wall side to the central axis side of the stirring tank 11 is stably generated in the stirring tank 11. .. Since this circulating flow boundary flow has almost no shearing force, mixing is hardly performed between the upper part and the lower part with this flow as a boundary.

Therefore, the auxiliary stirrer 123 is provided at such a position, and is rotated together with the stirring blade 122 according to the rotation of the stirring shaft 121. As a result, the circulating flow boundary flow collides with the flow generated by the rotation of the auxiliary stirrer and the extending portion 124 of the auxiliary stirrer 123, and while mixing at that portion, the vertical direction is different from that of the circulating flow boundary flow. It becomes the flow of. The upward flow mixes with the circulating flow C at the top of the tank, and the downward flow mixes with the stirring flow S at the bottom of the tank. Therefore, mixing between the upper part and the lower part of the liquid material L in the stirring tank 11 can be promoted.

The auxiliary stirrer 123 can be appropriately designed in consideration of the shape and size of the stirring tank 11, the stirring shaft 121, the stirring blade 122, etc., the increase in rotational power when the auxiliary stirrer 123 is installed, and the like.

The mass of the auxiliary stirrer 15 is not particularly limited, but is preferably 1/2 or less of the total mass of the stirring shaft 121 and the stirring blade 122 from the viewpoint of increasing the stirring efficiency without increasing the initial stirring power. However, if the stirring shaft 121 starts to rotate, a large stirring power is not required, so that the mass of the auxiliary stirring tool 15 may be more than 1/2 of the total mass of the stirring shaft 121 and the stirring blade 122.

FIG. 4 is a schematic view of an auxiliary stirrer attachment device. As shown in FIG. 4, as the auxiliary stirrer 123a, for example, in the mounting device 125a that covers at least a part around the stirring shaft, the extending portion 124 is formed so as to extend from the outer surface. Can be done. The stirring shaft and the extending portion may be integrally formed.

The shape of the auxiliary stirrer 123 is not particularly limited as long as it has a shape other than the disk shape centered on the stirring shaft 121 and can come into contact with the circulation flow boundary B and / or its vicinity, and is rod-shaped or plate-shaped. Etc., a combination of rod-shaped parts, etc. (see, for example, FIG. 9) may have any shape. From the viewpoint of more efficiently mixing the upper circulation flow C and the lower stirring flow S of the liquid material in the stirring tank 11, the volume of the rotating body formed with the rotating shaft 121 of the auxiliary stirrer 123 as the rotating shaft is defined. It is preferable to make it smaller. For example, rather than arranging the rectangular plate-shaped auxiliary stirrer 123 so as to coincide with the vertical direction of the stirring tank 11, the width direction of the rectangular frame-shaped (for example, "R" -shaped) auxiliary stirrer 123 Is arranged so as to coincide with the vertical direction of the stirring tank 11, because the volume of the rotating body is reduced, which is preferable. This reduces the power required for the assistive device. However, when the rod-shaped auxiliary stirrer is used in a state where it intersects the stirring shaft 121 perpendicularly, the range in which the mixing effect can be obtained is narrow in the vertical direction of the stirring tank 11.

The number of auxiliary stirrers 123 is not particularly limited as long as it is 1 or more. Further, the size of the auxiliary agitator 123 is not particularly limited as long as it has a shape capable of contacting the circulation flow boundary B and / or a range in the vicinity thereof.

5 to 11 are schematic views of the auxiliary stirrer according to the present embodiment, (a) is a schematic view of the upper surface, and (b) is a schematic view of the side surface. The "upper surface" and "side surface" of the auxiliary stirrer coincide with the "upper surface" and "side surface" of the stirring tank in the installed state of the auxiliary stirrer.

The auxiliary stirrer 123b shown in FIG. 5 has two extending portions 124b extending from the attachment device 125b and arranged in a straight line, and as shown in the side view (FIG. 5B), 2 The two extending portions 124b are arranged on one horizontal plane.

The auxiliary stirrer 123c shown in FIG. 6 has two extending portions 124c extending in a straight line extending from the attachment 125c, and as shown in the side view (FIG. 6B), 2 The two extending portions 124c are arranged at an angle of 30 ° from the horizontal direction.

The auxiliary stirrer 123d shown in FIG. 7 has two extending portions 124d extending in a straight line from the attachment 125d, and the two extending portions 124d have the attachment 125d side end. It has a shape that extends further up and down at different ends. That is, as shown in the side view (FIG. 7 (b)), such a shape forms the letter "H" by the two extending portions 124d.

The auxiliary stirrer 123e shown in FIG. 8 has four extending portions 124e extending from the attachment device 125e. In the top view (FIG. 8A), all four extending portions 124e are arranged at right angles to two adjacent extending portions. As shown in the side view (FIG. 8B), the four extending portions 124e are arranged in one horizontal plane.

The auxiliary stirrer 123f shown in FIG. 9 is formed by joining eight rod-shaped portions extending from the mounting device 125f to one annular portion on the end side different from the mounting device 125f side end. is there. As shown in the side view (FIG. 9B), the extending portion 124f is arranged in one horizontal plane.

The auxiliary stirrer 123g shown in FIG. 10 can be considered to be a partially cut portion of the annular portion of the auxiliary stirrer 123f shown in FIG. The auxiliary stirrer 123g has an extending portion 124e. In the top view (FIG. 10A), all four extending portions 124g are arranged at right angles to the two adjacent extending portions. The end portion different from the 125 g side end portion of the attachment has a shape that extends substantially perpendicular to the extending portion in the horizontal direction. As shown in the side view (FIG. 10B), the four extending portions 124g are arranged in one horizontal plane.

The auxiliary stirrer 123h shown in FIG. 11 has six extending portions 124h extending from the attachment device 125h. In the top view (FIG. 11A), all six extending portions 124h are arranged so as to form 60 ° with two adjacent extending portions. As shown in the side view (FIG. 11B), the six extending portions 124h are arranged in one horizontal plane.

(Determination of circulating flow boundary)
Hereinafter, a method for determining the position of the circulation flow boundary (height from the bottom of the stirring tank 11) will be described. The circulation flow boundary is a point where the upward flow and the downward flow suddenly change when the flow of the liquid material in the stirring tank 11 is measured while gradually hanging down the flow direction meter. If the device (size, shape), stirring blade (size, shape), number of stirrings, amount of liquid material, type, gas supply amount, bubble diameter, etc. change, the circulation flow boundary also changes, so it is actually Try to get closer to the mixed environment of.

The position of the circulation flow boundary (height from the bottom of the stirring tank 11) can also be calculated by calculation. Hereinafter, a detailed description will be given with reference to FIG. FIG. 12 is a schematic vertical cross-sectional view of a gas-liquid mixing device for explaining a method of calculating a circulating flow boundary.

と表すことができる。 The inner wall of the circulation flow boundary height of the agitating tank 11 and S _s, the height of the circulation flow boundary of the stirring shaft 121 side and S _e. The height of the circulation flow boundary is the distance from the bottom of the stirring tank 11. _{Let y be the difference between the height S s} of the circulating flow boundary on the inner wall side of the stirring tank 11 and the height of the circulating flow boundary on the stirring shaft 121 side.

It can be expressed as.

で表すと仮定し、反応槽内の代表流速をＶ_２とした場合に、

と表すことができることが分かった。式（３）を用いた場合、高さＳ_ｅは攪拌槽１１の代表長Ｌの１０％以内の誤差で推定可能である。 By our experiments, the flow velocity v at a distance r ₃ from the stirring shaft

Assuming that it is represented by, and the representative flow velocity in the reaction vessel is V ₂ ,

It turned out that it can be expressed as. When using the equation (3) can be estimated with high S _e is the error of within 10% of the characteristic length L of the agitating tank 11.

で表すことができる。 Note that V ₂ can be calculated from the discharge flow rate V _s from the stirring blade 11 and the volume of the liquid material, and the discharge flow rate V _s uses d (diameter of the stirring tank 11) / r ₂ (diameter of the stirring blade 122). hand

Can be represented by.

Further, the circulating flow boundary flow is regarded as a flow in which an ascending flow generated from the bottom of the stirring tank 11 along the inner wall and a descending flow generated from the upper part (liquid level) of the stirring tank 11 along the inner wall merge. It is also possible.

_{If the representative velocity V btm} of the liquid substance near the bottom surface of the stirring tank 11 _{and the representative velocity V top} of the liquid substance on the liquid surface can be measured with a flow velocity meter, the height of the liquid substance in the stirring tank 11 (liquid). _{As the surface height) h and the height imp top} from the bottom surface of the stirring tank to the top of the stirring blade, S _s may be obtained as follows.

として、式（４）又は（５）に代入し、Ｖ_２を算出する。 Further, assuming that the turning radius of the stirring blade 11 is r ₂ and the rotation speed of the stirring blade 122 is ω, the average velocity v ₁ of the liquid material discharged from the stirring blade 122 is the amount of liquid material V _{s discharged from the stirring blade 122.} a discharge area pi] r ₂ ² divided by the ^{_{(V s / πr 2 2)}} . On the other hand, the amount of liquid material V _s is expressed as V _s ∝ω × (2r ₂ ) ³ when the diameter of the stirring blade is 2r _2. Considering the width H of the stirring blades and the number n of the stirring blades 122, assuming that the discharge direction is only downward,

As, into equation (4) or (5) to calculate the _{V 2.}

(Near range of circulating flow boundary)
Since the auxiliary stirrer 123 is rotating, there is always a portion that moves relative to this flow and a portion that moves away from the flow. Therefore, the "neighborhood range" means that _{even when the radius of gyration rj} or the rotation speed ω of the auxiliary stirrer 123 is smaller than the flow velocity, the mixture is mixed between the upper part and the lower part of the stirring tank 11 by the portion that moves relative to the flow. At least the range in which the effect can be obtained. When calculating by calculation, for example, it is calculated as follows.

以内の距離である。 A difference (y) occurs between _{the height S s} on the inner wall side of the stirring tank 11 at the _{circulation flow boundary and the height S e} on the stirring shaft 121 side at the circulation flow boundary. Therefore, particularly when the auxiliary stirrer 123 is a combination of thin rod-shaped or thin rod-shaped portions, the stirring blade 122 has the stirring blade 122 in the horizontal direction from the stirring shaft 121 to the endmost portion from the viewpoint of particularly improving the stirring efficiency. When the length of _{the auxiliary stirrer 123 is r j} (cm) and the rotation speed is ω (rpm), the range of the installation height of the auxiliary stirrer 123 in the direction of the stirring shaft 121 is up and down from the circulation flow boundary.

Within a distance.

Further, in order to sufficiently obtain the effect of splitting the bubbles and reducing the diameter of the bubbles (reducing the diameter), it is preferable that the moving speed of the end of the auxiliary stirrer 123 is larger than the flow velocity of the flow at the boundary of the circulating flow.

When changing the operating conditions such as changing the rotation speed of the stirring blade or changing the gas supply amount during one operation (for example, from the start to stop of the sequential reaction or during one batch reaction). In the case where the height of the circulation flow boundary changes due to the influence of the change in the conditions, a plurality of auxiliary stirrers 123 may be installed according to the respective heights.

Further, even when the operation is performed under the condition that the fluctuation of the circulation flow boundary is likely to occur and the fluctuation changes with a certain width, by providing a plurality of auxiliary stirrers 123 and arranging them in a part of the vicinity range. A sufficient mixing effect can be obtained even if only the generated effective flow is arranged so as to be in contact with the circulation flow boundary.

As the auxiliary stirrer, in addition to the configuration having the extending portion 124, it is conceivable to use a tubular body so as to surround the stirring shaft 121, but in this case, after the circulating flow boundary flow collides with the tubular body. Since the flow velocity is reduced and the shearing force in the liquid is significantly reduced, the mixing efficiency is reduced. Further, in such a case, the bubbles do not disperse and split due to the decrease in the flow velocity and the shearing force, the coalescence progresses rapidly, the bubbles become coarse, the area of the gas-liquid interface decreases, and the efficiency of dissolution and reaction becomes large. It may decrease.

Further, when the neighborhood range is calculated by another calculation or an experiment, it may be a point that the mixing ratio obtained under the actual conditions of mixing is greatly changed while changing the position of the auxiliary stirrer 123.

[Gas supply pipe]
The gas supply port is arranged below the stirring blade 122.

The gas supplied from the gas supply port of the gas supply pipe 14 becomes bubbles in the liquid, which causes buoyancy. In order for the circulating flow boundary flow to constantly exist at a stable position, it is preferable to keep the buoyancy generated in the bubbles in the vicinity of the gas supply pipe 14 in a small state and to put it on the circulating flow by stirring by the stirrer 12. The smaller the bubble diameter, the smaller the buoyancy. For that purpose, it is preferable to place the bubbles in a stirring stream near the gas supply pipe 14. Therefore, the position of the gas supply pipe 14 is preferably arranged below the stirring blade 122.

Further, the gas supply pipe 14 may be provided with a gas supply port such as a single pipe or a plurality of pipes. It is preferable to use a ring type sparger as the gas supply pipe 14 in order to efficiently disperse the gas supplied to the liquid material as bubbles and generate the circulating flow boundary flow so as to have little bias in the height direction. .. The shape of the gas supply does not matter as long as it can be arranged evenly around the stirring shaft.

The amount of gas supplied is not particularly limited, but is preferably 1/10000 or more and 1/100 or less per second, and more preferably 1/50000 or more and 1/200 or less with respect to the amount of liquid matter on a volume basis. It is preferably 1/20000 or more and 1/500 or less.

The type of gas is not particularly limited, and for example, a gas such as air, nitrogen, or oxygen can be used in a liquid substance according to a desired chemical reaction. In addition to the gas that functions as a direct drug that reacts only between the gas and the liquid containing the chemical solution in the liquid material, the reaction that contributes to the reaction in a form that affects the chemical reaction in the liquid material. It can also contain a gas that acts as an aid. For example, in a chemical reaction in a liquid material, when dissolved oxygen in the liquid material affects this chemical reaction, the effect is reduced by supplying nitrogen from the gas supply pipe 14 to reduce the amount of dissolved oxygen. Nitrogen in the case corresponds to this.

[Additional part for chemicals, etc.]
The gas-liquid mixing device 1 according to the present embodiment may be provided with a chemical solution addition unit (not shown) depending on its use. The chemical solution addition section adds the chemical solution or the like to the liquid material of the stirring tank 11.

As the chemical solution, a solution containing a liquid solution, a slurry, or a solution containing a solid substance according to a desired chemical reaction can be used. It can also contain a component adjusting agent for a chemical solution, a trace amount of a dispersant and a surfactant that do not contribute to a chemical reaction, and the like.

≪Gas-liquid mixing method≫
The gas-liquid mixing method according to the present embodiment is, for example, a method that can be performed using the gas-liquid mixing device 1 described above, and specifically, a circular or polygonal bottom surface having all angles of 90 ° or more. A stirring tank 11 having a baffle plate 13 arranged so that the width direction is from the inner wall side of the stirring tank 11 toward the center of the stirring tank 11 when the stirring tank 11 is viewed from above. When the liquid material is housed inside the stirring gas 11 and the gas is supplied to the stirring tank from the gas supply port of the stirring gas supply pipe and the liquid material and the gas are mixed by the stirring machine 12, the stirring tank 11 is used as the stirring machine 12. Auxiliary stirrer 123 including a stirring shaft 121 hanging from the upper part, a stirring blade 122 provided perpendicular to the stirring shaft 121, and an extending portion 124 extending from the stirring shaft 121 toward the inner wall of the stirring tank 11. The extending portion 124 has a circulating flow boundary and / or a circulating flow boundary in which at least a part thereof exists between the circulating flow generated in the upper part of the liquid material in the stirring tank 11 and the stirring flow generated in the lower part thereof. It is characterized in that those arranged so as to be in contact with the vicinity range thereof are used, and as the gas supply pipe 14, one having a gas supply port arranged below the stirring blade 122 is used.

Hereinafter, examples of the present invention will be described in more detail, but the present invention is not limited to the following examples.

The height S _e of the circulation flow boundary of the stirring shaft 121 side, a value calculated by the equation (3), in order to verify the integrity of the measured values, the following experiment was performed.

On the inner wall of a cylindrical stirring tank having an inner diameter of dm, n baffle plates having a width of 1 / 11d and a length of 0.96h were provided at equal intervals so that the central angles of the circles on the bottom surface of the stirring tank were equal.

For Test Nos. 1 to 4, the baffle plate was installed below the stirring blade. Further, the baffle plate was arranged so as not to be separated from the bottom surface and the inner wall of the stirring tank.

In other examples, the baffle plate was placed below the stirring blade. The baffle plate was separated from the bottom surface of the stirring tank by 0.04 h. The baffle plate was separated from the inner wall by 0.03 h.

In such a stirring tank, the liquid material is placed at a height of 80% of the height of the stirring tank, for example, Test No. In the case of 1, the tank was housed up to a height of 0.31 m from the bottom with respect to a tank height of 0.39 m.

As the stirring blade, a rotating diameter of 2 rm, a width of the stirring blade H, and n number of stirring blades were used. The stirring blade was stirred at a rotation speed of ω rpm during the test.

The gas supply pipe is circular with a diameter of 1 / 40d, and 32 gas supply ports having a diameter of less than φ mm are provided evenly in the circumferential direction. With this gas supply pipe, the bubble diameter becomes about 1 mm. All gas supply ports were arranged facing upward. The gas was supplied at a rate of 0.7 kg / s.

Table 1 below shows the inner diameter d of the stirring tank, the height of the liquid material in the stirring tank h, the diameter of the stirring blade 2r, the width of the stirring blade (in the direction perpendicular to the diameter) H, the number of blades n, and the number of rotations of the stirring shaft ω. , the diameter of the stirring shaft rs, bubble size phi (expected value) observed in the liquid surface, the measured value of the height S _e of the circulation flow boundary of the stirring shaft near (in Table 1, referred to as "measured value".) and the calculated value of S _e calculated using equation (3) (in Table 1, referred to as "calculated value of S _e".) shows a representative length of the reaction vessel, the error rate of the S _e. Incidentally, the "error rate S _e", the difference between the calculated value of the measured values and S _e of S _e (absolute value) is a value obtained by dividing the characteristic length of the agitating tank. Further, the actual measurement method is a point in which the upward flow and the downward flow suddenly change when the flow of the liquid substance in the stirring tank is measured while gradually hanging down the flow direction meter.

Test No. In any of 1 to 10, the error rate of the circulating flow boundary was less than 10%, and it was found that the height of the circulating flow boundary near the stirring axis could be determined using the above equation (3).

[Example]
On the inner wall of a cylindrical stirring tank having an inner diameter of 8.68 m and a height of 10.4 m, three baffle plates having a width of 0.75 m and a length of 10 m were provided at intervals of 120 ° at the central angle of the circle on the bottom surface of the stirring tank. The baffle plate was placed 0.4 m away from the bottom surface of the stirring tank and below the stirring blade. In addition, it was separated from the inner wall by 0.3 m.

The stirring blade used had a rotating diameter of 3 m and 16 stirring blades. The stirring blade was stirred at a rotation speed of 43 rpm during the test.

A total of three types of auxiliary stirrers, A to C, were prepared. The auxiliary stirrer A is a rod-shaped body having a length of 2 m and a square shape having a cross section of 5 cm perpendicular to the length direction, attached so as to be horizontal and symmetrical with respect to the stirring axis. The auxiliary stirrer B is an instrument having an H-shaped vertical cross section, and has a square shape with a cross section of 5 cm from the stirring shaft (perpendicular to the length direction of the rod) and two rods with a length of 0.63. The body was arranged so as to extend horizontally from the stirring axis and the two rods were arranged in a straight line (corresponding to one H-shaped horizontal line). The central portion of the rod-shaped body having a length of 2 m was attached to the stirring shaft side and the other end side of the two rod-shaped bodies so that the length direction coincided with the vertical direction (H-shaped vertical direction 2). Corresponds to the line of the book.) Auxiliary instrument C is a square-shaped body with a cross section of 5 cm perpendicular to the length direction, and a rod-shaped body with a length of 1.7 m attached so as to be horizontal and symmetrical with respect to the stirring axis. It is provided in.

The gas supply pipe is circular with a diameter of 6 m, and 32 gas supply ports with a diameter of less than 1 mm are provided evenly along the circumference thereof. With this gas supply pipe, the bubble diameter becomes about 1 mm. All gas supply ports were arranged facing upward. The gas was supplied at a rate of 0.68 kg / s.

Six addition ports of the chemical solution were arranged at the same height above the liquid level of the liquid substance in the stirring tank. On the circumference of a circle with a diameter of 7.4 m (concentric circle with the bottom surface of the stirring tank) centered on the stirring shaft, a central angle of 40 ° is set between 6 points where the chemical solution is added and 3 places where the baffle plate is adjacent to each other. Arranged to make a circle. The chemical solution was supplied into the stirring tank at a rate of 500 kg / s. In addition, the chemical solution was discharged from a position 10.4 m in the height direction from the bottom surface of the container by an overflow method.

In order to confirm the state of stirring, a methacrylic resin (specific gravity: about 1 g / cm ³ ) colored red with safranin was added from the vicinity of the gas supply port. As the methacrylic resin, a spherical resin having a diameter of 1 mm and high hydrophilicity was used. Based on safranin, a total of 100 g was added at a rate equivalent to 1 g / 1 s.

The test was carried out according to the following procedure. First, gas was supplied from the gas supply pipe and a liquid material was supplied from the upper part of the stirring tank, and stirring was started when the liquid height reached 10.4 m. Approximately 30 minutes after the start of stirring, the height of the circulating flow boundary was measured using a flow direction meter. To measure the height of the circulating flow boundary, the measuring instrument was pulled down in the depth direction, and the point where the flow direction changed was measured. After that, the resin dispersed in water was started to be charged from the resin inlet. The liquid level was observed, and the time from charging until the vicinity of the liquid level became almost uniform with a color corresponding to the "light peach" color was measured by comparing with a commercially available color sample book. The stirring efficiency was evaluated by the reciprocal of the product of time and power of the stirrer. Table 2 below shows the values when the value of the stirring efficiency (the reciprocal of the product of the time and the power of the stirrer) of the comparative example in which the auxiliary stirrer is not set is 100%.

Table 2 below shows the position of the circulating flow boundary, the type of auxiliary agitator (any of A to C above), the cross-sectional shape of the extending portion (in the cross section perpendicular to the extending direction), and the length of the extending portion. Stirring radius r _j , 1.2√ (ωr _j ), position of auxiliary stirrer, viscosity of liquid material, density of liquid material, power required for uniform mixing, time required for uniform mixing, stirring efficiency (relative value) Is shown. The circulation flow boundary and the position of the auxiliary stirrer are vertical distances from the bottom of the stirring tank.

From the results shown in Table 2, it is possible to improve the stirring efficiency of the liquid material in the stirring tank by arranging the extending portion of the auxiliary stirring tool and the effective flow generated by the auxiliary stirring tool so as to be in contact with the circulation flow boundary. Do you get it.

1 Gas-liquid mixer 11 Stirrer tank 12 Stirrer 121 Stirrer shaft 122 Stirrer blade 123, 123a, 123b, 123c, 123d, 123e, 123f, 123g, 123h Auxiliary stirrer 124, 124a, 124b, 124c, 124d, 124e, 124f, 124g, 124h Extension 125, 125a, 125b, 125c, 123d, 123e, 123f, 123g, 123h Mounting equipment 13, 13a, 13b Baffle plate 14 Gas supply pipe L Liquid material S Stirring flow C Circulating flow B Circulating flow boundary

Claims (5)

A stirring tank, a stirrer, a baffle plate, and a gas supply pipe are provided.
The stirring tank has a circular shape or a tubular shape having a polygonal bottom surface having all angles of 90 ° or more, and can accommodate a liquid substance inside the stirring tank.
The stirrer includes a stirring shaft hanging from the upper part of the stirring tank, a stirring blade provided substantially perpendicular to the stirring shaft, and an extending portion extending from the stirring shaft toward the inner wall of the stirring tank. The extending portion has at least a part thereof between the circulating flow generated in the upper part of the liquid material in the stirring tank and the stirring flow generated in the lower part thereof. Arranged so as to contact the circulating flow boundary and / or its vicinity
The baffle plate is arranged so that the width direction of the baffle plate is directed from the inner wall side of the stirring tank toward the center of the stirring tank when the stirring tank is viewed from above.
The gas supply pipe has a gas supply port toward the inside of the stirring tank, and the gas supply port is arranged below the stirring blade.
Gas-liquid mixer. The extending portion has a rod shape.
The gas-liquid mixer according to claim 1. The gas supply pipe has an annular shape.
The gas-liquid mixer according to claim 1 or 2. The gas supply pipe has a plurality of the gas supply ports.
The gas-liquid mixing device according to any one of claims 1 to 3. It is a gas-liquid mixing method that mixes gas and liquid material.
A cylindrical stirring tank having a circular or polygonal bottom surface with all angles of 90 ° or more, and when the stirring tank is viewed from above, the width direction is from the inner wall side of the stirring tank to the stirring tank. A liquid substance is housed inside a stirring tank in which a baffle plate is arranged so as to face the center of the stirring gas, and gas is supplied to the stirring tank from the gas supply port of the stirring gas supply pipe to separate the liquid substance and the gas. When mixing with a stirrer
As the stirrer, a stirring shaft hanging from the upper part of the stirring tank, a stirring blade provided perpendicular to the stirring shaft, and an extending portion extending from the stirring shaft toward the inner wall of the stirring tank are provided. It has an auxiliary stirrer including, and the extending portion is a circulation in which at least a part thereof exists between a circulating flow generated in the upper part of the liquid material in the stirring tank and a stirring flow generated in the lower part thereof. Use one that is placed in contact with the flow boundary and / or its vicinity.
The mixing is performed using the gas supply pipe whose gas supply port is arranged below the stirring blade.
Gas-liquid mixing method.

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