JP7105446B2 - Reactor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a reactor for introducing a gas into a liquid phase for reaction.

2. Description of the Related Art As a reaction apparatus such as a chemical plant, a reaction apparatus is often used in which chemical treatment is performed by introducing a gas into a liquid phase such as a solution or slurry in a reaction vessel while stirring the reaction vessel.

For example, U.S. Pat. No. 5,400,000 discloses a shaft rotatable about the longitudinal axis of the vessel and attached to the shaft are first and second axially spaced radially extending impellers. A mixing vessel is disclosed. Specifically, in this mixing vessel, the first impeller includes a plurality of curved blades operable to move the fluid axially toward the second impeller, the second impeller axially It includes a plurality of curved blades operable to move fluid toward the first impeller, and a gas inlet is provided in the bottom surface of the vessel. In Patent Literature 1, by using a mixing container having such a configuration, a strong turbulent flow area is generated in the central portion of the mixing container, so that mixing of liquids in the container can be easily controlled.

However, in such a mixing vessel, when large bubbles are introduced from the large gas inlet provided in the center, they reach the liquid level at the top of the mixing vessel before the diameter of the bubbles in the mixing vessel becomes small. There's a problem. Therefore, even if such a mixing vessel 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 in the reaction vessel. Because of the longer time that is circulated and retained in the liquid, the amount of gas components dissolved in the liquid phase increases, and as a result, the effect of increasing the gas concentration in the liquid phase and improving the reaction efficiency can be expected. In other words, in order to improve the efficiency of the reaction, it is important to maximize the amount of small bubbles in the gas to be introduced in the liquid phase.

Known techniques for reducing the diameter of bubbles in a liquid phase include a method using a sparger (air diffuser) and a method in which gas is blown under a stirring blade to split the bubbles with the blade. For example, it is known that when a large amount of gas is blown in, the stirring blades idle due to a flooding phenomenon, and the amount of gas dissolved in the liquid decreases. A technique is disclosed in which a ring sparger having a diameter larger than that of a blade is used to allow blown air bubbles to flow onto a liquid flow circulating within the device.

However, when trying to apply the sparger to a reactor into which gas is introduced, the pressure of the gas blown into the device from the sparger is increased to exceed the sum of the internal pressure of the reaction vessel and the pressure loss of the sparger. need to press. In addition, since the sparger has a small bubble outlet diameter, the pressure loss is large. Therefore, especially when the internal pressure of the reaction vessel is pressurized, there is a problem that the cost of pressurizing equipment for the introduced gas is high. Furthermore, depending on the reaction, reaction products including intermediates or residues after the reaction may become deposits that clog the small bubble outlets of the sparger. There is also the problem that the Due to these various problems, it was sometimes difficult to use a sparger in the reactor.

In a reactor into which a gas is introduced, it is preferable to maximize the diameter of the gas-injecting pipe and the outlet diameter to minimize pressure loss. However, it is well known that the bubble diameter of bubbles discharged from a gas blowing pipe depends on the outlet diameter of the gas blowing pipe, and minimizing the pressure loss results in a large bubble diameter. An increase in bubble diameter means a decrease in the area of the gas-liquid interface, which is not preferable. For this reason, there is a demand for a technique for reducing the diameter of large-diameter bubbles discharged from a large-diameter outlet with low pressure loss.

Japanese Patent Publication No. 2009-536095 JP 2014-113564 A

The present invention has been made in view of such circumstances, and provides a reaction apparatus capable of introducing a gas into the reaction liquid with a structure that is simple and can be realized at low cost. Another object of the present invention is to provide a reactor capable of efficiently dividing gas bubbles having a large diameter to sufficiently reduce the diameter of the bubbles.

In a reaction apparatus comprising a reaction vessel, a stirrer, and a gas blowing pipe, the present inventors have found that a plurality of projections are formed on the outer surface of the gas blowing pipe corresponding to the downstream side with respect to the liquid flow generated by the stirrer. By forming a group of protrusions, the bubbles released from the gas blowing pipe can be efficiently divided, thereby making it possible to reduce the diameter of the bubbles.

(1) A reaction vessel that is a liquid phase storage tank, a stirrer vertically installed in the center of the reaction vessel, and a hollow space vertically installed in the reaction vessel at a position closer to the outer peripheral wall than the stirrer. and a gas blowing pipe having a gas blowing port on the lower end side, wherein the stirrer is capable of forming a liquid flow from the center of the reaction vessel toward the outer peripheral wall The reaction device, wherein the gas injection pipe has a group of protrusions formed on the outer surface thereof in the downstream direction of the liquid flow in a region extending vertically upward from the vicinity of the gas injection port as a starting point.

According to the reaction apparatus of (1), although it is a device that introduces gas into the reaction liquid by means of a gas blowing pipe 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 By efficiently dividing the bubbles released from the gas blowing pipe by the group of projections formed on the side surface of the gas blowing pipe with special consideration given to the relationship between , the bubble diameter can be made small.

According to the present invention, a reaction apparatus capable of introducing gas into a reaction liquid with a structure that can be realized at a simple and low cost can efficiently remove large-diameter gas bubbles introduced into the reaction liquid. It is possible to provide a reactor in which the cell diameter can be sufficiently reduced by dividing.

BRIEF DESCRIPTION OF THE DRAWINGS It is a longitudinal cross-sectional schematic diagram which shows the whole structure of the reaction apparatus of this invention. FIG. 2 is an enlarged view of the vicinity of the outlet (gas blowing port) of the gas blowing pipe in part A of FIG. 1, and is a diagram for explaining the positional relationship between the liquid flow and the region where the projection group is formed. FIG. 3 is a schematic diagram showing an example of a group of protrusions that are a constituent element of the reaction apparatus of the present invention.

Hereinafter, the details of the reactor, which is one of the specific embodiments of the present invention, will be described with appropriate reference to the drawings. The present invention is not limited to the embodiments described below, and various modifications are possible within the scope of the present invention.

FIG. 1 is a schematic diagram of a longitudinal section of a reactor 1 that is one 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. In the reactor 1, a reaction liquid in a liquid phase such as a liquid or slurry is contained in a reaction vessel 10, and a gas that contributes to a chemical reaction is introduced from a gas injection pipe 30 in a state in which a liquid flow is generated by a stirrer 20. Then, a chemical reaction is caused while stirring the gas in the liquid phase.

The gas introduced into the reaction vessel 10 is not particularly limited, and 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 having a circular cross section in a horizontal cross section, in which a reaction liquid is stored up to a predetermined height, and a chemical reaction takes place in the reaction liquid. give rise to The reaction vessel 10 may be open-topped or closed-topped. The top surface (when closed) and the bottom surface of the reaction vessel 10 are not limited to flat surfaces. and the side surface may have a curved portion.

[mixer]
The stirrer 20 has a function of stirring the reaction liquid contained in the reaction vessel 10 . The stirrer 20 includes a stirring shaft 21 that is suspended from the top 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 have

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

The stirring blades 22 are rotated at a predetermined speed with the stirring shaft 21 as the rotation axis, so that a liquid flow is introduced into the reaction liquid from the center of the reaction vessel 10 toward the outer peripheral wall, preferably from the center toward the outer peripheral wall. Any liquid flow may be generated as long as it can generate an obliquely downward liquid flow that descends vertically downward. The liquid flow along the direction of the arrow indicated below the stirring blade 22 in FIG. can be stirred efficiently. The stirring blade 22 is not limited to a specific shape or the like as long as it has a shape and installation mode that can generate such a liquid flow, but a plurality of stirring blades as shown in FIG. 1 are appropriately combined. 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 the above-described liquid flow can be generated. In addition, 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 injection pipe 30 introduces a gas that contributes to the chemical reaction into the reaction liquid contained in the reaction vessel 10, and is a hollow tubular member having a gas injection port at its lower end.

As shown in FIG. 1, the gas injection pipe 30 is inserted substantially perpendicularly to the surface of the reaction liquid at a horizontal position that is closer to the outer wall than the center of the reaction vessel 10 and does not interfere with the rotation of the stirring blade 22. It is In addition, regarding the arrangement of the gas blowing pipe 30, the gas blowing port is arranged at a position where the strength (flow rate and/or flow velocity) of the liquid flow becomes as large as possible in relation to the above liquid flow. Arrangement is preferred.

The portion of the gas blowing pipe 30 near the gas blowing port at the lower end thereof, which includes the region where the group of projections 31 is formed, is oriented vertically downward, or is at an angle difference from the direction. is oriented within 20°. Since the portion including the region where the projection group 31 is formed is oriented in the direction within the above angle range, the projection group 31 formed near the gas inlet facilitates the division of the bubbles by the liquid flow. Advantageous effects of the present invention can be expressed more efficiently. Details of the action and effect of promoting the division of air bubbles by the group of protrusions 31 will be described later.

(protrusion group)
As shown in FIG. 1, a projection group 31 is formed on the outer surface of the gas blowing pipe 30 . The main feature of the reactor 1 of the present invention is that the projection group 31 is formed in a manner optimized for the direction and strength of the liquid flow generated in the reaction vessel 10 .

The shape and forming range of the group of protrusions 31 are optimized for the liquid flow in the reaction vessel 10 . As for the specific formation range, the downstream half range with respect to the liquid flow direction of the reaction liquid (for example, the arrow direction in FIG. 1) of the entire circumference of the outer surface of the gas injection pipe 30 is the protrusion group 31 is set.

Here, the "downstream half range" of the outer surface of the gas blowing pipe 30 with respect to the liquid flow direction specifically refers to the region B in FIG. 2 of the outer surface. As shown in FIG. 2 , when the reaction liquid flows in the direction indicated by the arrow with respect to the center point of the gas blowing pipe 30 , the projection group 31 is arranged such that the liquid flow is at the center point of the gas blowing pipe 30 is formed on the outer surface of the gas blowing pipe 30 within a range surrounded by a line segment that forms an angle of 90° or more with a line directed toward .

The range in which the group of protrusions 31 should be formed on the outer surface of the gas injection pipe 30 (the downstream half range with respect to the liquid flow direction of the reaction liquid) is the direction in which the liquid flow direction is from the center of the reaction layer toward the outer peripheral wall direction. As long as, that is, when the stirrer 20 generates a liquid flow in such a direction, the preferable formation position of the projection group 31 corresponding to this is, of the entire circumference of the outer surface, It is within the range of half of the side near the outer peripheral wall of the reaction vessel 10 .

In addition, as shown in FIGS. 1 and 3, the formation range of the projection group 31 in the vertical direction is a range in which the lower end portion is in the vicinity of the gas blowing port and extends vertically upward as appropriate from the lower end portion. good.

Here, the bubbles released from the outlet of the gas blowing pipe 30 rise due to buoyancy, move in the direction from the center of the reaction vessel 10 toward the outer peripheral wall due to the liquid flow, and rise due to the buoyancy. These bubbles are desirably divided by the shearing force of the liquid flow to become bubbles with a sufficiently small diameter during this upward movement. However, the bubbles immediately after being released from the gas blowing pipe 30 are not yet sufficiently divided and have a large bubble diameter, so they are easily affected by buoyancy, and the bubbles hit the downstream side of the liquid flow, near the outer surface of the gas blowing pipe 30. will rise toward the liquid surface.

On the other hand, in the reactor 1 , the unevenness due to individual protrusions forming the protrusion group 31 promotes turbulence of the liquid flow near the outer surface of the gas injection pipe 30 . Then, the air bubbles released from the gas inlet at the lower end of the gas blowing pipe 30 are sheared by the velocity difference of the liquid flow thus generated, thereby promoting the breakup of large-diameter bubbles.

FIG. 3 is a view of the gas blowing pipe 30 of FIG. 1 viewed from the downstream direction of the liquid flow, that is, from the outer peripheral wall side of the reaction vessel. A protrusion group formed by forming a plurality of protrusions in a range extending vertically upward from the lower end of the gas blowing pipe 30 in the vicinity of the gas blowing port on the outer surface corresponding to the downstream side with respect to the liquid flow direction of the gas blowing pipe 30. 31 are formed. The height and the number of individual projections forming the projection group 31 are not particularly limited. When the length (L) of is not particularly limited, the length (L) is not particularly limited. All of these may be appropriately adjusted according to various conditions related to the reactor (flow rate of gas to be introduced, diameter of gas injection pipe, flow velocity of liquid phase, etc.).

1 Reactor 10 Reaction Vessel 20 Stirrer 21 Stirring Shaft 22 Stirring Blade 30 Gas Blowing Tube 31, 31a, 31b, 31c Projection Group

Claims (1)

a reaction vessel that is a liquid phase storage tank;
a stirrer vertically installed in the center of the reaction vessel;
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 having 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 vessel toward the outer peripheral wall,
The reaction apparatus, wherein the gas blowing pipe has a group of protrusions formed in a region extending vertically upward from the vicinity of the gas blowing port on the outer surface of the liquid flow in the downstream direction.

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