JP7341389B2 - Reactor and chemical treatment method using the reactor - Google Patents

Description

The present invention relates to a reaction device for introducing a gas into a liquid phase and causing a reaction, and a chemical treatment method using such a reaction device.

2. Description of the Related Art Reactors used in chemical plants and the like are often used to carry out chemical treatment by stirring and introducing gas into a liquid phase such as a solution or slurry in a reaction vessel.

For example, Patent Document 1 discloses a shaft rotatable around the longitudinal axis of a container, and first and second impellers attached to the shaft and extending in the radial direction and spaced apart in the axial direction. A mixing vessel is disclosed. Specifically, in the mixing vessel, the first impeller includes a plurality of curved blades operable to move fluid axially toward the second impeller, and the second impeller axially moves the fluid toward the second impeller. It includes a plurality of curved blades operable to move fluid toward a first impeller and has a gas inlet in the bottom of the vessel. In Patent Document 1, by using a mixing container having such a configuration, a strong turbulent flow region is generated in the center of the mixing container, thereby making it possible to easily control the mixing of liquids within the container.

However, in such a mixing container, if large air bubbles are introduced through the large gas inlet in the center, the bubbles will reach the liquid level at the top of the mixing container before the bubble diameter decreases within the mixing container. There's a problem. Therefore, even if such a mixing container is used for a chemical reaction, the amount of gas that does not contribute to the reaction increases, resulting in a decrease in reaction efficiency.

It is important for the gas used in the chemical reaction in the reaction vessel to have a small bubble diameter in the liquid phase within the reaction vessel. The smaller the bubbles, the larger the area of the gas-liquid interface, and the longer the bubbles circulate and stay in the liquid, so the amount of gas components dissolved into the liquid phase increases, and as a result, the amount of gas components dissolved in the liquid phase increases. This is because the effect of increasing the gas concentration and improving the reaction efficiency can be expected.

Known techniques for reducing the diameter of bubbles in the liquid phase include a method using a sparger (diffuser tube) and a method in which gas is blown under stirring blades to break up the bubbles. For example, it is known that when a large amount of gas is blown into the liquid, the stirring blades idle due to the flooding phenomenon, and the amount of gas dissolved into the liquid becomes small. As a countermeasure against this, Patent Document 2 discloses a technique in which a ring sparger having a diameter larger than the stirring blade is used to carry the blown air bubbles into the flow of liquid circulating within the device.

However, when trying to apply a sparger to a reaction device that introduces gas, the pressure of the gas blown into the device from the sparger exceeds the sum of the internal pressure of the reaction vessel and the pressure loss of the sparger. It is necessary to press. Further, since the sparger has a small bubble outlet diameter and therefore has a large pressure loss, there is a problem in that the cost of equipment for pressurizing the gas to be introduced becomes high, especially when pressurizing the internal pressure of the reaction vessel. Furthermore, depending on the reaction, reaction products including intermediates or residues after the reaction may become deposits that block the small bubble outlet of the sparger, and if the equipment is stopped to remove the deposits, the operating rate may be reduced. There is also the problem of a decrease in Due to these various problems, it has sometimes been difficult to use a sparger in a reactor.

In a reactor that introduces gas, it is preferable to make the diameter and outlet diameter of the gas blowing pipe as large as possible in order to minimize pressure loss. However, it is well known that the diameter of the bubbles discharged from the gas blowing tube depends on the outlet diameter of the gas blowing tube, and if the pressure loss is to be minimized, the bubble diameter will become large. An increase in the bubble diameter means that the area of the gas-liquid interface decreases, which is not preferable. For this reason, there is a need for a technique for reducing the large diameter bubbles emitted from the large outlet diameter with small pressure loss to a small bubble diameter.

Special Publication No. 2009-536095 Japanese Patent Application Publication No. 2014-113564

The present invention was made in view of the above circumstances, and provides a reaction device that can introduce gas into a reaction liquid with a simple and low-cost structure, or a reaction device that uses such a reaction device. The purpose of the present invention is to provide a reaction device, etc., which can efficiently break up large-diameter gas bubbles introduced into a reaction liquid and sufficiently reduce the bubble diameter, even though the chemical treatment method is conventional. .

The present inventors have proposed a reaction device including a reaction vessel, a stirrer, and a gas blowing tube, in which the lower end of the gas blowing tube is directed downstream with respect to the liquid flow generated by the stirrer. The present invention was completed based on the discovery that by tilting the tube, the bubbles emitted from the gas blowing tube can be efficiently broken up and the bubble diameter can be made sufficiently small.

(1) A reaction vessel which is a cylindrical liquid phase storage tank, a stirrer vertically installed in the center of the reaction vessel, and a stirrer vertically installed in the reaction vessel at a position closer to the outer peripheral wall than the stirrer. and a gas blowing tube that is a hollow tubular member having a gas blowing port on the lower end side, the stirrer forming a liquid flow from the center of the reaction vessel toward the outer peripheral wall. The reactor is a reactor capable of producing a reactor, wherein the gas blowing pipe is installed in such a manner that the lower end side thereof is oriented toward the downstream side of the liquid flow rather than vertically downward.

According to the reaction device (1), although it is a device that introduces gas into the reaction liquid through a gas blowing tube made of a hollow tubular member that has a simple structure and can be manufactured and used at low cost, the liquid flow of the reaction liquid is By appropriately adjusting the inclination angle of the gas blowing pipe with respect to the direction, the gas bubbles introduced into the reaction liquid can be efficiently separated and the bubble diameter can be sufficiently reduced.

(2) The reaction device according to (1), wherein the inclination angle of the gas blowing pipe is 20° or more and +40° or less in terms of angle difference from the vertically downward direction.

According to the reaction device (2), by optimizing the inclination angle of the gas blowing pipe to a more preferable angle range, it is possible to further improve the above-mentioned bubble breaking effect achieved by the invention (1).

(3) A chemical treatment method in which a gas is introduced into a liquid phase to cause a reaction, which comprises: a reaction vessel that is a cylindrical liquid phase storage tank; a stirrer vertically installed in the center of the reaction vessel; The reaction is carried out using a reaction device comprising a gas blowing pipe, which is a hollow tubular member vertically installed in a container at a position closer to the outer peripheral wall than the stirrer, and has a gas blowing port on the lower end side, In a state where the agitator is forming a liquid flow from the center of the reaction vessel toward the outer peripheral wall, the gas blowing pipe is moved so that the lower end side is closer to the downstream side of the liquid flow than vertically downward. A chemical treatment method in which a gas is blown into a liquid phase through the gas blowing tube while the gas is tilted toward the liquid phase.

According to the chemical treatment method (3), in a method using a reaction device in which gas is introduced into the reaction liquid through a gas blowing tube made of a hollow tubular member that has a simple structure and can be manufactured and used at low cost, the reaction liquid By appropriately adjusting the inclination angle of the gas blowing pipe with respect to the direction of the liquid flow, the gas bubbles introduced into the reaction liquid can be efficiently separated and the bubble diameter can be sufficiently reduced.

(4) The chemical treatment method according to (3), wherein the inclination angle of the gas blowing pipe when blowing the gas is 20° or more and +40° or less in terms of angle difference from the vertically downward direction.

According to the chemical treatment method (4), by optimizing the inclination angle of the gas blowing pipe to a more preferable angle range, the above-mentioned bubble breaking effect achieved by the invention (3) can be further improved.

According to the present invention, although the present invention is a reaction device capable of introducing gas into a reaction liquid with a simple and low-cost structure, or a chemical treatment method using a reaction device, the gas introduced into the reaction liquid is It is possible to efficiently divide the bubbles and sufficiently reduce the bubble diameter.

FIG. 1 is a schematic vertical cross-sectional view showing the overall configuration of the reaction apparatus of the present invention. FIG. 2 is a diagram schematically showing the action of the reaction device and the chemical treatment method using the reaction device of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a reaction apparatus and a chemical treatment method using the reaction apparatus, which are one specific embodiment of the present invention, will be described in detail with reference to the drawings as appropriate. Note that the present invention is not limited to the embodiments described below, and various changes can be made without changing the gist of the present invention.

<Reactor>
FIG. 1 is a schematic longitudinal cross-sectional view of a reaction apparatus 1 that is an embodiment of the present invention. As shown in the figure, the reaction apparatus 1 includes a reaction vessel 10, a stirrer 20, and a gas blowing pipe 30.

The reaction device 1 stores a reaction liquid in a liquid phase such as a liquid or slurry in a reaction vessel 10, and introduces a gas contributing to a chemical reaction from a gas blowing pipe 30 while a liquid flow is generated by a stirrer 20. This causes a chemical reaction to occur while stirring the gas in the liquid phase. The gas introduced into the reaction vessel 10 is not particularly limited, and for example, gases such as air, nitrogen, and oxygen can be used depending on the desired chemical reaction in the reaction liquid.

[Reaction container]
The reaction vessel 10 is a cylindrical liquid phase storage tank that usually has a circular cross section when viewed in a horizontal cross section, and contains a reaction liquid to a predetermined height inside the reaction liquid. cause a reaction to occur. The reaction container 10 may have an open top surface or may be closed. The top surface (when closed) and the bottom surface of the reaction vessel 10 are not limited to those that are flat, but may have a curved portion on the top surface or bottom surface in a vertical cross-sectional view, or may have a top surface or bottom surface. It may have a curvature portion between the side surface and the side surface.

[mixer]
The stirrer 20 has a function of stirring the reaction liquid contained in the reaction container 10. The stirrer 20 includes a stirring shaft 21 that is suspended from the upper part of the reaction vessel 10, and a stirring blade 22 that is provided at the lower end of the stirring shaft 21 perpendicularly to the axial direction of the stirring shaft 21. and has.

It is preferable that the stirring shaft 21 is arranged so that its center coincides with the center of the circular reaction vessel in the cross-sectional view of the reaction apparatus 1. Thereby, the gas introduced into the reaction apparatus can be more efficiently dispersed in the reaction liquid.

The stirring blade 22 rotates at a predetermined speed using the stirring shaft 21 as a rotating shaft, thereby causing a liquid flow in the reaction liquid from the center of the reaction vessel 10 toward the outer circumferential wall, preferably from the center toward the outer circumferential wall. Any material that can generate a diagonally downward liquid flow that descends in a vertically downward direction may be used. The liquid flow along the direction of the arrow shown below the stirring blade 22 in FIG. can be stirred efficiently. The stirring blade 22 is not limited to a particular shape as long as it has a shape and installation mode that can generate such a liquid flow, but it is formed by appropriately combining a plurality of stirring blades as shown in FIG. 1. A propeller-shaped one can be preferably used.

The number of stirring blades 22 is preferably plural, but is not particularly limited as long as it can generate the liquid flow in the manner described above. Further, a plurality of such stirring blades 22 may be arranged at different vertical positions of the stirring shaft 21 in a vertically spaced manner.

[Gas blowing pipe]
The gas blowing tube 30 introduces a gas contributing to a chemical reaction into the reaction liquid contained in the reaction vessel 10, and is a hollow tubular member having a gas blowing port at its lower end.

As shown in FIG. 1, in the reaction apparatus 1 of the present invention, the gas blowing pipe 30 is installed in a state of being inclined along the direction of the liquid flow f with respect to the vertical direction. As shown in FIG. 3, the direction in which the gas blowing pipe 30 is tilted is optimized with respect to the liquid flow f within the reaction vessel 10. Specifically, the gas blowing pipe 30 is tilted so that the lower end side having the gas blowing port 31 faces toward the downstream side of the liquid flow f formed by the stirring blade 22 rather than vertically downward. .

As shown in FIG. 1, the gas blowing pipe 30 is placed in a horizontal position closer to the outer circumferential wall than the center of the reaction vessel 10 and does not interfere with the rotation of the stirring blade 22. In relation to the above-mentioned liquid flow, it is preferable to be at a position where the strength (flow rate and/or flow velocity) of the liquid flow is as large as possible.

In conventional reactors, a hollow tubular member for introducing gas into the liquid phase is installed with its lower end, where the gas inlet is located, facing vertically downward. In this case, a part of the gas blown from the gas blowing port did not separate from the tubular member and floated along the side surface of the tube while maintaining the bubble diameter at the time of release.

In contrast, in the reaction of the present invention, the gas blowing pipe 30 is installed in an appropriately inclined state toward the downstream side along the direction of the liquid flow f, as shown in FIG . In the device 1, almost all of the gas discharged from the gas blowing port 31 can be quickly separated from the gas blowing pipe 30.

As shown in FIG. 2 , after being released from the gas blowing pipe 30, the bubble g1 that quickly separates from the gas blowing pipe 30 and rises in the liquid phase becomes smaller in diameter due to the shearing of the liquid flow f. They float up in the liquid phase while forming bubbles g2 and g3. In this way, in the reaction apparatus 1, the bubble diameter of the gas discharged from the gas blowing pipe 30 can be made sufficiently small, the contact area between the gas and the reaction liquid can be increased, and the reaction efficiency can be improved. . Note that the shear of the liquid increases as the turbulent state increases, and the larger the Reynolds number, a dimensionless number representing the turbulent flow state, the smaller the bubble diameter. Here, the preferable Reynolds number is 10,000 or more.

The inclination angle of the gas blowing pipe 30 should be such that the angle difference (angle α in FIG. 2 ) with respect to the vertical downward direction is 20° or more and 40° or less, with the direction from the downstream side of the liquid flow f being positive. is more preferable. If this angle of inclination is set to 0° or more, the gas released from the gas blowing pipe 30 will easily separate from the gas blowing pipe 30 and rise in the liquid phase, and the bubble diameter will be reduced by shearing of the liquid flow f. be able to. Furthermore, when the inclination angle is 20° or more, almost all of the gas released into the reaction liquid is quickly separated from the tubular member, and the effects of the present invention are exhibited in a generally ideal state. It becomes like this.

On the other hand, by setting the above-mentioned inclination angle to 40 degrees or less, the gas discharged from the gas blowing pipe can be divided into gas lumps. If the angle of inclination is less than 20°, the gas will float a short distance away from the blow tube. The shearing that the gas receives near the blowing tube is small, and since the gas is concentrated, it is difficult to change the bubble diameter to a small one. Furthermore, if the inclination angle is greater than 40°, the area where the shear created by the blowing tube exists becomes smaller, and the speed at which the gas moves away from the blowing tube increases, resulting in less ideal conditions. As a result, it becomes difficult for the bubbles to change to smaller diameters.

As shown in FIG. 2, the gas blowing pipe 30 is not only installed so that the part that is in contact with the liquid phase has an inclination angle with respect to the vertical downward direction; It may be installed in a direction perpendicular to the liquid level, bent only near the gas inlet at the lower end, and installed so as to have an inclination angle with respect to the vertically downward direction. In this case, the inclination angle is the angle between the direction of the gas inlet and the vertically downward direction.

<Chemical treatment method>
The present invention can also be carried out by adjusting the arrangement of the gas blowing pipes in a conventional reaction apparatus having a reaction vessel and a stirrer, at least when blowing gas, to the same arrangement as in the reaction apparatus 1. can. In this case, as above, the direction in which the gas blowing pipe is tilted is the direction in which the lower end is directed toward the downstream side of the liquid flow, and the angle of inclination is 20 degrees or more in terms of the angle difference from the vertically downward direction, as in the above case. The angle is preferably 40° or less.

1 Reactor 10 Reaction container 20 Stirrer 21 Stirring shaft 22 Stirring blade 30 Gas blowing pipe

Claims (4)

a reaction vessel which is a cylindrical liquid phase storage tank;
a stirrer vertically installed in the center of the reaction vessel;
A reaction device comprising: a gas blowing pipe, which is a hollow tubular member vertically installed in the reaction vessel at a position closer to the outer peripheral wall than the stirrer, and has a gas blowing port on the lower end side,
The stirrer is a device capable of forming a liquid flow from the center of the reaction container toward the outer peripheral wall,
The gas blowing pipe is installed in a state where the lower end side is inclined so as to face in a direction closer to the downstream side of the liquid flow than vertically downward.
Reactor. The reaction device according to claim 1, wherein the inclination angle of the gas blowing pipe is 20° or more and 40° or less, with the direction from the downstream side of the liquid flow being positive, based on the angle difference from the vertically downward direction. A chemical treatment method in which a gas is introduced into a liquid phase and reacts,
a reaction vessel which is a cylindrical liquid phase storage tank;
a stirrer vertically installed in the center of the reaction vessel;
The method is carried out using a reaction apparatus comprising a gas blowing pipe, which is a hollow tubular member vertically installed in the reaction vessel at a position closer to the outer peripheral wall than the stirrer, and has a gas blowing port on the lower end side. I,
In a state where the stirrer forms a liquid flow from the center of the reaction vessel toward the outer peripheral wall, the gas blowing tube is oriented so that the lower end side thereof is directed toward the downstream side of the liquid flow rather than vertically downward. Blowing gas into the liquid phase from the gas blowing tube while tilting the tube as shown in FIG.
Chemical treatment methods. According to claim 3, the inclination angle of the gas blowing pipe when blowing the gas is set to 20° or more and 40° or less, with the angle difference from the vertical downward direction being positive in the direction from the downstream side of the liquid flow. Chemical treatment methods described.

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