JP2021122757A - Gas dissolving device - Google Patents

Abstract

To provide a gas dissolving device and a gas dissolving method which efficiently dissolve desired gas in the water, and can enhance dissolved concentration of the gas in the water.SOLUTION: A gas dissolving device 1a includes a tank 2 whose upper part is formed with a gas phase composed of oxygen having a pressure higher than an atmospheric pressure, a water supply pipe 3 whose one end is connected to a water supply port 2a of the tank 2, a water supply pump 5 whose discharge port is connected to the other end of the water supply pipe 3, a pipe 6 connected to a suction port of the water supply pump 5, an air feed pipe 7 which is connected to the vicinities of the inlet and the suction port of the water supply pump 5 and feeds oxygen to the water supply pipe 3, a drain pipe 4 whose one end is connected to a drain port 2b of the tank 2, and a swirl flow generator 8 which is installed in the gas phase in the tank 2 and feeds mixed liquid of water and oxygen from the water supply pipe 3; and forms a film-like swirl flow fs by water jetted into the gas phase in the tank 2 from the swirl flow generator 8.SELECTED DRAWING: Figure 1

Description

The present invention relates to an apparatus and a gas dissolution method for dissolving a desired gas in water in a lake, a fish and shellfish farm, a sewage treatment plant, or the like, and in particular, can increase the concentration of the gas dissolved in water. The present invention relates to a gas dissolving apparatus and a gas dissolving method.

Conventionally, an air diffuser has been installed at the bottom of lakes and marshes in order to increase the dissolved oxygen concentration in water. However, it is not possible to efficiently increase the dissolved oxygen concentration in water simply by supplying air into the water as in the air diffuser.
As a solution to such a problem, for example, Patent Document 1 has the name "gas dissolving device", and an invention aimed at stably producing a dissolved gas solution in which a desired gas is dissolved in a liquid. Is disclosed.

The invention disclosed in Patent Document 1 is a device for dissolving a predetermined gas component in a gas into a liquid by a pressure difference between the gas and the liquid, and is a container having a closed space whose inside is pressurized to atmospheric pressure or higher. The main body, three ring-shaped rectifying plates attached to the inner wall of the container main body, and after extending horizontally to the center of the container, upward in the container so as to discharge the liquid vertically upward. A liquid injection tube that is bent and has a discharge nozzle at the tip, two bladed rectifying plates attached to the vertical portion of the liquid injection tube, a gas supply tube, a gas discharge tube, and a liquid discharge tube. It has a structure provided.
In a gas melting device having such a structure, when water is supplied to the inside of the container body, the water rectified by the rectifying plate flows down like a waterfall to form a curtain-shaped water film. As a result, the contact area between the gas and the liquid is increased, so that the gas is easily dissolved in the liquid.

Further, Patent Document 2 discloses an invention under the name of "gas replacement device", which aims to reliably execute exhaust from the container body and intake air to the container body.
The invention disclosed in Patent Document 2 is a gas melting device disclosed in Patent Document 1, in which a liquid supply having a structure similar to those of a liquid injection pipe, a gas supply pipe, a gas discharge pipe and a liquid discharge pipe is used instead of the liquid injection pipe, the gas supply pipe, the gas discharge pipe and the liquid discharge pipe. It is equipped with a pipe, a replacement gas supply pipe, and a gas discharge pipe. A shielding member composed of a curved plate having an upwardly convex curved surface is installed on the upper part of the liquid supply pipe, and the replacement gas supply pipe is inserted from the center of the ceiling so that the discharge port is located at the center of the upper surface of the shielding member. It has a structure that has been improved.
In a gas replacement device having such a structure, when a replacement gas having a pressure higher than that supplied from the liquid supply pipe is supplied into the container body from the replacement gas supply pipe, a liquid forming a curtain-shaped water film is formed. It has the effect of expelling the gas contained therein to the replacement gas. Therefore, if the device is installed in a lake or the like and the gas contained in the water is replaced with oxygen, the dissolved oxygen concentration in the water can be increased.

Patent Document 3 discloses an invention relating to a device for generating microbubbles and carbonated springs in a bathtub or the like under the name of "microbubble / carbonated spring generator and gas-liquid mixing tank".
The gas-liquid mixing tank disclosed in Patent Document 3 is a closed type mixing container, which includes a water injection nozzle for injecting water from a bathtub, a gas injection nozzle for injecting carbon dioxide gas, an upper limit water level of the mixing container, and the like. The structure is provided with a water level detecting member for detecting the lower limit water level and a collision member for stirring provided at a position facing the water injection nozzle.
In a gas-liquid mixing tank having such a structure, when water mixed with air is injected from a water injection nozzle, the water collides with a collision member to agitate air and carbon dioxide. This promotes the dissolution of air and carbon dioxide in water.

Patent Document 4 discloses an invention relating to a device for generating fine bubbles in water under the name of "fine bubble generator based on a swirling unit".
The invention disclosed in Patent Document 4 includes a swirling unit that swirls the supplied water and gas while colliding with each other to flow out dissolved water, and a swirling unit that is sprayed from the swirling unit in the form of a spray to come into contact with air and then falls. The structure is provided with a dissolution tank in which the dissolved water is housed and a nozzle unit installed in the dissolution tank to eject the dissolved water into the water to generate fine bubbles.
According to such a structure, a large amount of fine bubbles can be generated with low power consumption.

Patent Document 5 discloses an invention under the name of "fine bubble generator", which relates to a device that takes in water and air to generate and discharge water containing fine bubbles.
The invention disclosed in Patent Document 5 includes an air introduction section having an air intake port for taking in air from the outside, an air mixing section for mixing air and water taken in from the air introduction section to form an air mixed water, and an air mixing section. A pressurizing pump that pressurizes and sends the air-mixed water, a generation discharge section that generates and discharges fine bubble-containing water from the air-mixed water pressurized by the pressurizing pump, and an air introduction section are provided. It has an ozone generation mechanism.
A plurality of pore-shaped injection ports are formed on the lower surface, and an injection nozzle forming a hollow disk is provided so as to project inward of the tank under pressure, and the above-mentioned air-mixed water is injected. The structure is such that vigorous air bubbles and water flow are formed by vigorously injecting air from the injection port of the nozzle toward the dissolution promoting portion below, and the dissolution of air in water is promoted.

Patent Document 6 discloses an invention relating to an apparatus capable of improving the absorption efficiency of carbon dioxide gas under the name of "carbonated beverage producing apparatus".
The invention disclosed in Patent Document 6 is a carbonated beverage manufacturing apparatus that dissolves carbon dioxide gas in a treatment liquid supplied to a circulator tank formed so that carbon dioxide gas filled therein can be held at a predetermined pressure. The structure is arranged above the circulator tank and provided with a nozzle that discharges the treatment liquid in the form of a mist or a thin film.
According to such a structure, carbon dioxide gas is absorbed by the treatment liquid discharged into the inside of the circulator tank in the form of mist or thin film through the nozzle, so that the absorption efficiency of carbon dioxide gas is improved. do.

Further, the applicant of the present application has already applied for an invention relating to a highly productive device capable of generating a large amount of fine bubbles under the name of "gas dissolving device" (Patent Document 7).
The invention disclosed in Patent Document 7 includes a pump for delivering a liquid, a tank connected to a discharge port of the pump by a conduit, and an ejector for ejecting a fluid supplied from the conduit into the tank. It is characterized in that a gas-liquid mixed fluid generated by injecting a gas to be dissolved in a liquid into a suction port or a conduit of a pump is ejected from an ejector into a gas phase region in a tank.

In the gas dissolving device having the above structure, the gas-liquid mixed fluid ejected from the ejector into the gas-phase region in the tank contains fine water droplets and atomized particles, and the area in contact with oxygen is large. Has the effect of being easily dissolved. In addition, since the gas-liquid mixed fluid changes into water droplets, mist, or the like, it has the effect of staying in the gas phase region for a longer period of time as compared with the case where water is naturally dropped.
That is, in the invention disclosed in Patent Document 7, oxygen is easily dissolved in the gas-liquid mixed fluid, and the gas-liquid mixed fluid is in contact with oxygen for a long time, so that the amount of dissolved oxygen in the liquid can be increased. It is possible.

Japanese Unexamined Patent Publication No. 2013-27814 Re-table 2016/113877 Japanese Unexamined Patent Publication No. 2008-237965 Special Table 2013-523448 Japanese Unexamined Patent Publication No. 2010-155479 Japanese Unexamined Patent Publication No. 2015-147183 Japanese Unexamined Patent Publication No. 2018-176094

Regarding the invention disclosed in the prior art, the ease of dissolving oxygen in water droplets and fog will be described with reference to FIG. 9 as appropriate. 9 (a) and 9 (b) are schematic views showing the states of water and water droplets jetted in the form of mist, respectively. The portion shown by hatching in FIG. 9B represents the range in which oxygen in contact with water droplets can be dissolved.
In the inventions disclosed in Patent Document 1 and Patent Document 2, the liquid supplied to the inside of the container body is rectified by a rectifying plate and then flows down like a waterfall to form a curtain-shaped liquid film. However, since this liquid film is formed by free fall of the liquid and has an appropriate thickness, the gas in the container cannot be brought into contact with the liquid inside the liquid curtain.
As described above, in the inventions disclosed in Patent Document 1 and Patent Document 2, the liquid discharged from the liquid injection pipe is not sufficiently in contact with the gas in the container, so that the gas in the container is not sufficiently contacted. It is not easy to dissolve it efficiently in a desired liquid.

The invention disclosed in Patent Document 3 has a structure in which water mixed with air collides with a collision member immediately after being injected from the water injection nozzle, but the water injected from the water injection nozzle collides with the collision member. It is unlikely that water in which the gas is sufficiently dissolved can be obtained by contacting with the gas filling the gas-liquid mixing tank in a short time until the collision.
Further, although the structure is such that the water is agitated by colliding with the collision member, it is difficult to improve the dissolution efficiency of the air in the water only by mixing the air with the water and agitating the water.
That is, the invention disclosed in Patent Document 3 has a problem that a desired gas cannot be efficiently dissolved in water.

The invention disclosed in Patent Document 4 is to swirl the water and the gas flowing into the swirling unit while colliding with each other. However, simply swirling the water and the gas does not sufficiently dissolve the gas in the water. Can not.
Further, in the invention disclosed in Patent Document 4, it is necessary to limit the inflow amount of water into the dissolution tank in order to inject the water flowing into the dissolution tank in the form of spray. When the water is atomized, the area in contact with oxygen increases as shown in FIG. 9A, so that oxygen is easily dissolved. However, since the amount of water that comes into contact with oxygen at one time is small, the amount of dissolved water (water in which oxygen is dissolved) produced per unit time is extremely reduced as compared with the case where water is not sprayed in the form of mist. Therefore, in such a structure, oxygen cannot be efficiently dissolved in water.
Further, the invention disclosed in Patent Document 4 has a structure in which dissolved water contained in a dissolution tank is injected into water to generate fine bubbles. In this case, the amount of dissolved oxygen in the water elapses over time. There was a problem that it could not be applied to fish and shellfish farms because it easily decreased.

The invention disclosed in Patent Document 5 has a structure in which the air-mixed water is ejected from the injection nozzle toward the lower dissolution promoting portion, but the air-mixed water injected from the injection nozzle reaches the dissolution promoting portion. It is unlikely that the gas will dissolve in the air-mixed water by coming into contact with the gas in the tank in a short time until.
Further, even if vigorous air bubbles and water flow are formed in the dissolution promoting portion by the air mixed water injected from the injection nozzle, it is difficult to improve the dissolution efficiency of air in water by itself.
That is, the invention disclosed in Patent Document 5 has a problem that air cannot be efficiently dissolved in water.

In the invention disclosed in Patent Document 6, a treatment for filling the tank by spraying the treatment liquid from the upper part of the circulator tank so as to reach the tank wall surface and uniformly spraying the entire tank with a spray nozzle. The structure is such that carbon dioxide gas is absorbed by the treatment liquid while the liquid droplets fall or the treatment liquid that hits the tank wall surface flows down in the form of a thin film.
However, since this thin film is formed by free fall of the treatment liquid and has an appropriate thickness, carbon dioxide gas cannot be brought into contact with the liquid inside the thin film, and the thin film is a tank. Carbon dioxide gas cannot be brought into contact with the side that is in contact with the wall surface.
Further, when the treatment liquid is sprayed in the form of a mist by the spray nozzle, the area in contact with the carbon dioxide gas increases as described with reference to FIG. 9A in the case of injecting the treatment liquid in the form of a mist, so that the carbon dioxide gas is dissolved. Although it has the advantage of being easy to use, it is difficult to efficiently dissolve the carbon dioxide gas in the treatment liquid because the amount of the treatment liquid to be brought into contact with the carbon dioxide gas cannot be increased at one time.
Therefore, the invention disclosed in Patent Document 6 has a problem that not only carbon dioxide gas but also a desired gas cannot be efficiently dissolved in the treatment liquid.

In the invention disclosed in Patent Document 7, since the gas-liquid mixed fluid ejected from the ejector into the gas phase region in the tank contains fine water droplets and atomized particles, the area in contact with oxygen is large and oxygen is present. In addition to being easily dissolved, the gas-liquid mixed fluid changes into water droplets, mist, or the like, so that there is an advantage that the water stays in the gas phase region for a longer time than when water is naturally dropped.
However, when the gas-liquid mixture fluid ejected into the gas phase in the tank is in the form of water droplets, oxygen in the tank can only come into contact with the surface of the water droplets Wd as shown in FIG. 9B. In this case, since oxygen dissolves only in the water near the surface of the water droplet Wd but not in the water inside the water droplet Wd, the concentration of oxygen dissolved in the water does not increase so much. On the other hand, when the gas-liquid mixed fluid ejected into the gas phase in the tank is atomized, the amount of the gas-liquid mixed fluid that is brought into contact with oxygen at one time is increased as described with reference to FIG. 9 (a). Processing efficiency is not good because it cannot be done.
As described above, it is considered that the present invention still has room for improvement in that oxygen is efficiently dissolved in water.

The present invention has been made in response to such conventional circumstances, and is a gas dissolving device and a gas capable of efficiently dissolving a desired gas in water and increasing the dissolved concentration of the gas in water. It is an object of the present invention to provide a dissolution method.

In order to achieve the above object, the gas melting device according to the first invention is provided with a water supply port and a drainage port at the upper part and the lower part, respectively, and a gas phase composed of a gas having a pressure higher than the atmospheric pressure is formed inside. A tank, a water supply pipe for supplying water to the inside of this tank through a water supply port, a water supply pump for sending water to this water supply pipe, and a pipe for supplying water to this water supply pump. An air supply pipe for supplying gas to the tank, a drain pipe for discharging the treated water accumulated in the lower part of the tank from the drain port, and a water supply pipe installed in the tank and supplied from the water supply pipe through the water supply port. It is characterized by including a swirling flow generator that ejects water into a gas phase and forms a swirling flow composed of a film thinner than a film formed by linearly traveling water.

In the gas melting device having the above structure, the swirling flow formed by the swirling flow generator is formed by water that is ejected from the ejection hole and travels in a spiral shape that gradually expands in diameter toward the front. Therefore, it has the effect that the film thickness becomes thinner toward the front due to the action of centrifugal force, and finally becomes granular or atomized. In addition, the swirling flow has a longer path until the water ejected from the ejection hole becomes granular or atomized, and the flow is slower than that of the membranous flow formed by linearly traveling water. It has an effect that the time during which the above-mentioned water can form a film and come into contact with the surrounding gas is much longer than in the case of the above-mentioned film-like flow. Further, in the swirling flow, the swirling water constantly updates the surface in contact with the surrounding gas, so that the surrounding gas is more easily dissolved as compared with the film-like flow.
Since the swirling flow is formed in the gas phase, it has the effect of increasing the amount of dissolved oxygen in the treated water as compared with the case where fine bubbles are generated in the liquid phase.

The gas melting device according to the second invention is formed elongated in the vertical direction, is installed so that at least a part of it is submerged in water, and has water supply ports and drainage ports at the upper and lower parts, respectively, and has an atmospheric pressure. A tank in which a gas phase consisting of a gas having a higher pressure is formed inside, a water supply pipe for supplying water to the inside of this tank through a water supply port, and a water supply pump for delivering water to this water supply pipe. And the piping for supplying water to this water supply pump, the air supply pipe for supplying gas to the tank, the air supply pump installed in this air supply pipe, and above the drain port and An exhaust port provided on the side surface of the tank so as to be located below the water surface, an exhaust pipe connected to this exhaust port, a valve installed in this exhaust pipe, and installed in the tank above the exhaust port. A swirling flow generator that ejects water supplied from a water supply pipe through a water supply port into the gas phase to form a swirling flow consisting of a film thinner than a film formed by linearly traveling water. It is characterized by having.

In the second invention, when the air supply pump is operated to supply air from the air supply pipe into the tank, a part of water is pushed out from the drain port and the gas-liquid interface moves downward, but the valve of the exhaust pipe When the valve is opened, the gas-liquid interface stays at that position, and the pressure of the gas phase in the tank is kept constant at a state higher than the atmospheric pressure.
Further, also in the second invention, since the structure is such that a swirling flow is formed by using a swirling flow generator in the gas phase showing a pressure higher than the atmospheric pressure, the swirling flow is the same as that of the first invention. It has a similar effect. Then, in the second invention, since the gas in the tank is constantly replaced, there is an action that the composition of the gas is kept constant.
Further, in the second invention, a branch pipe is connected to the air supply pipe upstream of the air supply pump, and a desired gas component contained in the air supplied from the air supply pipe to the tank is supplied from the branch pipe to the air supply pipe. Increasing the proportion of the gas component has the effect of increasing the partial pressure of the gas component in the gas phase formed in the tank.

Further, in the third invention, in the first invention or the second invention, the swirling flow generator has a hollow portion and is substantially rotationally symmetric, and the diameter is reduced toward one of the axial directions of the rotational symmetry axis. The main body is provided so that the introduction hole connected to the water supply pipe opens in the peripheral wall portion in the tangential direction, and the reduced diameter portion is provided in the axial direction of the axis of rotational symmetry. It is characterized in that a ejection hole is provided so as to open to.
In the gas melting device having such a structure, in addition to the action of the first invention or the second invention, the water supplied from the water supply pipe to the inside of the swirling flow generator through the introduction hole is along the inner surface of the main body. When the main body moves in the direction of reducing the diameter while swirling, it has an action of forming a film-like swirling flow as a result of being radially ejected from the ejection hole while rotating by centrifugal force.

The gas dissolution method according to the fourth invention includes a step of forming a gas phase composed of a gas having a pressure higher than the atmospheric pressure inside a closed tank, and supplying water to the inside of the tank to supply water into the gas phase. It is characterized by including a step of forming a thin-film swirling flow composed of the above.
According to the fourth invention, as compared with the method of generating fine bubbles in the liquid phase and the method of forming a water film in the gas phase by linearly advancing water, the surrounding gas in the water to be treated Has the effect of being much easier to dissolve.

As described above, according to the first invention, it is possible to efficiently dissolve a desired gas in water to be treated and maintain a high concentration of the gas dissolved in the water. ..

According to the second invention, it is possible to easily adjust the pressure of the gas phase formed in the tank by changing the number of exhaust ports and the installation location. Further, in the second invention, since a sensor for detecting the position of the gas-liquid interface and a control mechanism for maintaining the gas phase formed in the tank at a constant pressure are not required, the manufacturing cost is reduced. It can be reduced. Then, according to the second invention, since the same swirling flow as in the first invention is formed in the gas phase showing a pressure higher than the atmospheric pressure, the effect exerted by the swirling flow in the first invention. Further, in the second invention, since the gas in the tank is constantly replaced and its composition is maintained, the dissolved concentration of the gas in the treated water discharged from the exhaust port can be kept constant. can. Further, according to the second invention, since it is easy to adjust the partial pressure of the desired gas component contained in the gas phase formed in the tank, the gas component is dissolved in the treated water discharged from the exhaust port. It is possible to increase the amount efficiently.

According to the third invention, in addition to the effect of the first invention or the second invention, the effect of being able to form a swirling flow made of a film thinner than the film formed by linearly traveling water can be obtained. Play.

According to the fourth invention, it is possible to efficiently dissolve a desired gas in water and increase the dissolved concentration of the gas in water.

(A) is a view showing the appearance of Example 1 of the gas melting apparatus according to the embodiment of the present invention, and (b) is a thin film swirl by a swirl flow generator in the tank in the figure (a). It is the figure which showed the state which the flow is generated enlarged. (A) is a cross-sectional view of a main part of the swirling flow generator shown in FIG. 1 (a) or FIG. 1 (b), and FIGS. It is a perspective view schematically showing a membranous flow formed by a swirling flow and water ejected from an ejection hole and traveling linearly, and (d) and (e) are B- in the figure (b), respectively. It is a cross-sectional view taken along the line B and a cross-sectional view taken along the line CC in the figure (c). (A) to (c) are photographs showing how a thin film swirling flow is formed by various swirling flow generators. (A) and (b) are graphs showing the amount of oxygen dissolved in water treated by the gas dissolving apparatus of the present invention. (A) and (b) are graphs showing the rate at which the amount of oxygen dissolved in water treated by the gas dissolving apparatus of the present invention changes. It is a graph which showed the time change of the oxygen concentration dissolved in the water treated by the gas dissolving apparatus of this invention and the conventional apparatus. It is a figure which showed the appearance of Example 2 of the gas melting apparatus which concerns on embodiment of this invention. It is a figure which showed the appearance of Example 3 of the gas melting apparatus which concerns on embodiment of this invention. (A) and (b) are diagrams schematically showing water and water droplets jetted in the form of mist, respectively.

The gas dissolving apparatus of the present invention will be specifically described with reference to FIGS. 1 to 8. In the following description, oxygen is dissolved in water, but the gas to be dissolved in water is not limited to oxygen. That is, in the gas dissolving apparatus of the present invention, the following actions and effects are similarly exhibited when a gas other than oxygen is dissolved in water.

FIG. 1 (a) shows an example of the appearance of the gas melting apparatus of the present invention, and FIG. 1 (b) is an enlarged view of the swirling flow generator shown in FIG. 1 (a). It shows how a membranous swirling flow is generated.
As shown in FIG. 1 (a), the gas melting device 1a is provided in a closed tank 2 in which a gas phase composed of oxygen having a pressure higher than the atmospheric pressure is formed in the upper part, and in the upper part of the tank 2. The water supplied from the water supply pipe 3 having one end connected to the water supply port 2a, the drainage pipe 4 having one end connected to the drainage port 2b provided at the bottom of the tank 2, and the pipe 6 connected to the suction port. The other end of the water supply pipe 3 is connected to the discharge port so that it can be sent to the water supply pipe 3, and the water supply pump 5 is connected to the inlet (in the case of a centrifugal pump, the impeller inlet) or the vicinity of the suction port. , The air supply pipe 7 that mixes oxygen with the water supplied from the pipe 6, and the swirl that is installed in the gas phase in the tank 2 and the mixed fluid of water and oxygen is supplied from the water supply pipe 3 through the water supply port 2a. The flow generator 8 is provided.

The drain pipe 4 is provided with a pressure adjusting valve 4a for maintaining the internal pressure of the tank 2, and the air supply pipe 7 is provided with a solenoid valve 7a for adjusting the amount of gas supplied. Further, the gas melting device 1a controls the opening degree of the electromagnetic valve 7a based on the detection results of the water level sensor 2c for detecting the upper limit water level and the lower limit water level of the water accumulated inside the tank 2 and the water level sensor 2c. A control unit (not shown) is installed. That is, the gas melting device 1a has a structure that stabilizes the water level in the tank by controlling the amount of gas supplied from the air supply pipe 7 to the tank 2 based on the water level in the tank detected by the water level sensor 2c. There is.
The gas melting device 1a is characterized in that a film-like swirling flow fs is formed by water ejected from the swirling flow generator 8 into the gas phase in the tank 2 as shown in FIG. 1 (b). ..

FIG. 2A is a cross-sectional view of a main part of the swirling flow generator 8 and shows a state in which the main body is cut in a plane including a rotation symmetry axis. Further, FIGS. 2B and 2C show a film-like swirling flow fs and a cylindrical ejection hole formed by the swirling flow generator 8 at a constant angle with respect to the cylindrical axis, respectively. It is a perspective view which shows typically the membranous flow f'formed by the water ejected linearly in the direction away from each other. Further, FIGS. 2 (d) and 2 (e) are a cross-sectional view taken along the line BB in FIG. 2 (b) and a cross-sectional view taken along the line CC in FIG. 2 (c), respectively. The portions shown by hatching in FIGS. 2 (d) and 2 (e) represent the range in which oxygen in contact with the swirling flow fs and the membranous flow f'can be dissolved.
As shown in FIG. 2A, the swirling flow generator 8 is formed so that the main body 9 having a hollow portion has substantially rotational symmetry and the diameter is reduced toward one of the axial directions of the rotational symmetry axis. ing. The peripheral wall portion 9a of the main body 9 is provided with an introduction hole 10 connected to the water supply pipe 3 via the water supply port 2a of the tank 2 so as to open in the tangential direction, and is rotationally symmetrical to the above-mentioned reduced diameter portion. An ejection hole 9b is provided so as to open in the axial direction of the shaft.

The mixed fluid of water and oxygen supplied from the water supply pipe 3 to the inside of the swirling flow generator 8 through the introduction hole 10 is along the inner surface of the peripheral wall portion 9a as shown by the broken line arrow A in FIG. 2 (a). While turning, the main body 9 moves in the direction of contraction. At that time, centrifugal force and centripetal force act on water and oxygen, respectively, due to the difference in specific gravity between water and oxygen, so that oxygen dissolved in the mixed fluid continuously gathers in the center of the main body 9, and the oxygen is continuously collected. As a result, the water ejected from the ejection hole 9b forms a film-like swirling flow fs as shown in FIG. 2 (b). At this time, since the oxygen forming the gas phase of the tank 2 exists not only outside the swirling flow fs but also inside the swirling flow fs, it comes into contact with the outer surface and the inner surface of the swirling flow fs as shown in FIG. do. As a result, the dissolved concentration of oxygen in the water forming the swirling flow fs is increased.

Even when water is ejected linearly from the ejection hole as shown by an arrow in FIG. 2 (c), a film-like flow f'having substantially the same shape as the swirling flow fs shown in FIG. 2 (b) is formed. NS. Since the swirling flow fs is formed by water that is ejected from the ejection hole 9b and travels in a spiral shape that gradually expands in diameter toward the front, the film thickness increases toward the front due to the action of centrifugal force. It becomes thin and eventually becomes granular or mist.
On the other hand, the membranous flow f'is formed by water ejected from the ejection hole and traveling linearly, and no centrifugal force is generated. That is, in the case of FIG. 2 (c), a water film that expands in a trumpet shape against gravity is formed only by the force of water ejected from the ejection hole and traveling linearly. It is necessary to eject more water from the ejection hole in a shorter time than in the case of b). Therefore, the film thickness of the film-like flow f'(see FIG. 2 (e)) is thicker than the film thickness of the swirling flow fs (see FIG. 2 (d)).

Therefore, when oxygen is in contact with the swirling flow fs, oxygen is dissolved in the water inside the swirling flow fs as shown in FIG. 2D, whereas oxygen is in contact with the membranous flow f'. In this case, as shown in FIG. 2 (e), oxygen dissolves only in the water near the surface of the membranous flow f'and does not dissolve in the water inside, so that the oxygen dissolved in the water The concentration is not so high.
Further, in the case of FIG. 2 (c), as compared with the case of FIG. 2 (b), the path until the water ejected from the ejection hole becomes granular or mist is shorter, and the flow is faster. The time during which the above-mentioned water can form a film and come into contact with the surrounding gas is much shorter than in the case of FIG. 2 (b).
Further, in the swirling flow fs, the swirling water constantly updates the surface in contact with the surrounding gas, so that the gas is dissolved as compared with the membranous flow f'in which such a phenomenon cannot occur. It has the effect of being easy.

As already described, Patent Document 1 and Patent Document 2 describe that the water rectified by the straightening vane flows down like a waterfall to form a curtain-shaped water film. Since this water film is formed by water that travels linearly due to free fall, its thickness hardly changes, and it is much thicker than the swirling flow fs shown in FIG. 2 (b). .. That is, in the gas dissolving apparatus of the present invention, a film thinner than the curtain-shaped water film formed by the natural drop of water as described in Patent Document 1 and Patent Document 2 is formed.
Further, in the curtain-shaped water film, since the water only travels linearly and does not swirl, the phenomenon that the surface in contact with the surrounding gas is constantly updated does not occur. Therefore, in the water film, the efficiency of dissolving the surrounding gas is lower than that of the swirling flow fs.
Although Patent Document 6 describes that the treatment liquid is released into a thin film inside the circulator tank, the efficiency of dissolving the surrounding gas (carbon dioxide gas) in the treatment liquid is carbon dioxide. It is considered that the efficiency at which carbon dioxide gas is dissolved in the swirling flow fs when the swirling flow fs is formed in the gas phase is significantly lower than the efficiency.

3 (a) to 3 (c) show a fine bubble generator (BT50) manufactured by Bubble Tank Co., Ltd., a gas-liquid mixer (TR6242) manufactured by Nomura Electronics Co., Ltd., and a swirl type fine bubble generator manufactured by Hatada Iron Works, respectively. It is a photograph showing how a thin film swirling flow is formed by a vessel (HFB20).
In the fine bubble generator shown in FIG. 3A, the main body 9 having substantially rotational symmetry in the swirling flow generator 8 shown in FIG. 2A is reduced in diameter toward both sides in the axial direction of the rotational symmetry axis. The structure is such that the ejection holes 9b are provided on both sides in the axial direction so as to form a pair.
Therefore, when this fine bubble generator is used in place of the swirling flow generator 8 shown in FIG. 2A, a pair of oxygen and water mixed fluids supplied from the water supply pipe 3 to the inside of the main body 9 are ejected. It is ejected from the holes 9b and 9b to form a thin-film swirling flow similar to the swirling flow fs shown in FIG. 2 (b) (see FIG. 3 (a)).

The gas-liquid mixer shown in FIG. 3B has a circular liquid chamber inside, is formed of a short disc-shaped cylinder having a substantially square U-shaped cross section, and one end is closed by an end wall. At the same time, it was connected to a mixing cylinder provided at the other end with an opening communicating with the liquid chamber, a water guide pipe provided in a tangential direction on the outer periphery of the liquid chamber so as to communicate with the liquid chamber, and an end wall of the mixing cylinder. It has a structure equipped with an air supply tube.
Therefore, when this gas-liquid mixer is used in place of the swirling flow generator 8 shown in FIG. It is ejected from the opening to form a thin-film swirling flow similar to the swirling flow fs shown in FIG. 2 (b) (see FIG. 3 (b)).

The swirl-type fine bubble generator shown in FIG. 3 (c) has a substantially hemispherical shape with a hollow inside, and has a gas-liquid outlet and a gas inlet at positions facing each other on the axis of rotational symmetry of the outer wall. A pressurized liquid introduction pipe connected in the direction perpendicular to the axis of rotational symmetry and a gas introduction pipe connected to the gas introduction port are provided in the vicinity of the gas-liquid outlet of the body.
The inner wall of the hollow portion forms a smooth inner surface of the hemisphere with the gas-liquid outlet as the apex, and the gas inlet side is a circular wall that closes the bottom surface of the hemisphere. The gas inlet has a substantially conical trapezoidal shape protruding from the wall body into the hollow portion along the axis of rotational symmetry, and forms a smooth curved surface from the inner wall of the hollow portion through the wall body to the side surface of the substantially conical trapezoidal shape. There is.

The gas introduction pipe is provided so as to penetrate the wall body and the gas introduction port from the outside of the body, and the pressurized liquid introduction pipe is provided with respect to the axis of rotational symmetry in the vicinity of the opening of the hollow inner wall of the gas liquid outlet. It is connected vertically. A pressurized liquid introduction port is formed on the inner wall of the hollow portion.
Therefore, when this swirl type fine bubble generator is used in place of the swirl flow generator 8 shown in FIG. 2 (a), the water supplied from the pressurized liquid introduction pipe and the gas introduction pipe to the inside of the body, respectively. And oxygen are ejected from the gas-liquid outlet of the body to form a thin-film swirling flow similar to the swirling flow fs shown in FIG. 2 (b) (see FIG. 3 (c)).

The swirling flow generator 8 of the gas melting device 1 is not limited to the structure shown in FIG. 2 (a), and for example, a structure shown in any one of FIGS. 3 (a) to 3 (c) is used. Also, a swirling flow fs can be formed in the gas phase inside the tank 2. And even in such a case, the action and effect of the present invention described with reference to FIG. 2B are similarly exhibited.

The graphs of FIGS. 4 (a) and 4 (b) show a fine bubble generator manufactured by Bubble Tank Co., Ltd. instead of the swirling flow generator 8 shown in FIG. 2 (a) in the gas dissolution device 1 (FIG. 3 (a). ) Is shown as a result of measuring the amount of dissolved oxygen in the water treated using).
The horizontal axis shows the gauge pressure inside the tank 2, and the vertical axis shows the amount of dissolved oxygen. The black circles represent the experimental results when the fine bubble generator is installed in the upper part of the tank 2, and the white triangles are the fine particles in the liquid phase formed by storing water in the bottom of the tank 2. It shows the experimental results when a bubble generator is installed.

In FIG. 4A, the flow rate of oxygen inside the air supply pipe 7 is 2 [L / min], and the water supply pipe 3 to the tank when the fine bubble generator is installed in the gas phase and the liquid phase. The temperatures of the water supplied to 2 are 26.2 [° C.] and 26.1 [° C.], respectively. Further, in FIG. 4B, the flow rate of oxygen inside the air supply pipe 7 is 3 [L / min], and the water supply pipe 3 to the tank when the fine bubble generator is installed in the gas phase and the liquid phase. The temperatures of the water supplied to 2 are 26.9 [° C.] and 27.0 [° C.], respectively.

In FIGS. 4 (a) and 4 (b), the higher the pressure in the tank, the higher the treatment regardless of whether the oxygen flow rate inside the air supply pipe 7 is 2 [L / min] or 3 [L / min]. It is shown that the amount of dissolved oxygen in the water is large, and that the amount of dissolved oxygen in the treated water is larger when the fine bubble generator is installed in the gas phase than when the fine bubble generator is installed in the liquid phase.
That is, according to the gas dissolution method of the present invention in which a swirling flow fs is formed in the gas phase, it is possible to increase the amount of dissolved oxygen in the treated water as compared with the conventional method of generating fine bubbles in the liquid phase. be.

The graphs of FIGS. 5 (a) and 5 (b) show the oxygen dissolution efficiency (OTE: Oxygen) for the water treated by the gas dissolving apparatus 1 in the experiment described with reference to FIGS. 4 (a) and 4 (b). The result of measuring Transfer Efficiency) is shown.
The horizontal axis shows the gauge pressure inside the tank 2, and the vertical axis shows the oxygen dissolution efficiency. The black circles represent the experimental results when the fine bubble generator is installed in the upper part of the tank 2, and the white triangles are the fine particles in the liquid phase formed by storing water in the bottom of the tank 2. It shows the experimental results when a bubble generator is installed.

The oxygen dissolution efficiency OTE is expressed by the following formula (1). However, in the formula (1), K _La is a general oxygen transfer capacity coefficient (1 / min), which is a value indicating the ability to transfer oxygen from the gas phase to the liquid phase in a unit time. Further, Cs is the saturated dissolved oxygen concentration (g / L), V is the volume of the tank 2 (L), Gs is the flow rate of oxygen inside the air supply pipe 7 (L / min), and ρ is the air density (g / L). , _OW is the mass fraction of oxygen in the air.

In FIGS. 5 (a) and 5 (b), the pressure in the tank is a constant value regardless of whether the oxygen flow rate inside the air supply pipe 7 is 2 [L / min] or 3 [L / min]. If it exceeds, the oxygen dissolution efficiency in the treated water may be lower when the fine bubble generator is installed in the gas phase than when the fine bubble generator is installed in the liquid phase, and the inside of the air supply pipe 7. When the oxygen flow rate is 2 [L / min], the oxygen dissolution efficiency is higher than when the oxygen flow rate inside the air supply pipe 7 is 3 [L / min].
That is, according to the gas dissolution method of the present invention in which a swirling flow fs is formed in the gas phase, fine bubbles are formed in the liquid phase by adjusting the flow rate of oxygen inside the air supply pipe 7 and the pressure in the tank. It is possible to increase the oxygen dissolution efficiency in the treated water as compared with the conventional method of generating.

The graph of FIG. 6 shows the results of measuring the temporal change of the dissolved oxygen concentration in the water treated by the gas dissolving apparatus of the present invention and the conventional apparatus.
The horizontal axis shows the time elapsed from the start of the measurement, and the vertical axis shows the concentration (measured value) of oxygen dissolved in 500 mmL of water treated by each device.
The black circles are the experimental results when the gas melting device 1 uses a fine bubble generator manufactured by Bubble Tank Co., Ltd. (see FIG. 3A) instead of the swirling flow generator 8 shown in FIG. 2A. The white diamonds represent the experimental results when the gas melting device manufactured by Daiei Seisakusho described in Patent Document 1 is used.

FIG. 6 shows that when the gas dissolving device 1a of the present invention is used, the dissolved oxygen concentration in the treated water is higher than when the conventional gas dissolving device described in Patent Document 1 is used, and the dissolved oxygen concentration is time. It shows that it does not easily decrease over time.
That is, according to the gas dissolution method of the present invention in which a swirling flow fs is formed in the gas phase, the dissolved oxygen concentration in the treated water is increased as compared with the method in which a curtain-shaped water film is formed in the gas phase by the natural fall of water. At the same time, it is possible to maintain the dissolved oxygen concentration in a high state.

FIG. 7 is a diagram showing the appearance of the gas dissolving device 1b according to the modified example of the gas dissolving device 1a of the first embodiment. The components shown in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted.
As shown in FIG. 7, in the gas melting device 1b, the air supply pipe 7 is connected to the inlet of the water supply pump 5 (in the case of a centrifugal pump, the impeller inlet) or the vicinity of the suction port in the gas melting device 1a of the first embodiment. Instead, it has a structure in which one end is connected to an air supply port (not shown) provided at the upper part of the tank 2. Further, in the air supply pipe 7, an air supply pump 11 is installed instead of the solenoid valve 7a, and a branch in which an electromagnetic valve 12a for adjusting the gas supply amount is installed on the upstream side of the air supply pump 11. The pipe 12 is connected. The air supply pipe 7 is used to supply air to the tank 2, and the branch pipe 12 is used to mix oxygen with the air supplied from the air supply pipe 7 to the tank 2.

In the gas melting device 1b, only water is supplied from the water supply pipe 3 to the inside of the swirling flow generator 8 through the introduction hole 10, but even with such a structure, the water ejected from the ejection hole 9b is supplied. As a result, a film-like swirling flow fs as shown in FIG. 2B is formed in the gas phase of the tank 2 as in the gas melting device 1a. Therefore, according to the use of the gas dissolution device 1b, the dissolved oxygen concentration in the treated water is higher than that in the case of using the conventional gas dissolution device described in Patent Document 1, and the dissolved oxygen concentration elapses over time. However, the action and effect of the gas dissolution device 1a, which is difficult to decrease, are similarly exhibited.

FIG. 8 is a diagram showing the appearance of the gas dissolving device 1c according to the modified example of the gas dissolving device 1b of the second embodiment. The components shown in FIGS. 1 to 3 are designated by the same reference numerals and the description thereof will be omitted.
As shown in FIG. 8, the gas melting device 1c is formed in the gas melting device 1b of the second embodiment in an elongated shape in the vertical direction, and 3 is inside a tank 2 installed so that at least a part of the gas melting device 1c is submerged in water. The swirling flow generators 8 are installed so that water can be supplied from the water supply pipes 3, respectively, and the drainage ports 2b and 2b are provided at the lower part of the tank 2 and above the drainage ports 2b and 2b. In addition, one ends of the exhaust pipes 13 and 14 are connected to the two exhaust ports 2d and 2d provided on the side surfaces of the tank 2 so as to be spaced apart from each other.

The water level sensor 2c is not installed in the tank 2. Further, the two exhaust ports 2d and 2d are both provided below the three swirling flow generators 8 and located below the water surface. That is, in the gas melting device 1c, the gas-liquid interface (boundary surface between the gas phase and the liquid phase) formed at the upper part of the tank 2 by the air supplied from the air supply pipe 7 is formed at a position lower than the water surface.

In the gas melting device 1c in which the inside of the tank 2 is filled with water, when the air supply pump 11 is operated to supply air from the air supply pipe 7 to the inside of the tank 2, a part of the water is discharged from the drain port 2b, As a result of being extruded from 2b, the gas-liquid interface moves downward and a gas phase is formed in the upper part of the tank 2.
However, if the solenoid valve 13a is opened, the air supplied from the air supply pipe 7 to the tank 2 passes through the exhaust pipe 13 to the tank when the gas-liquid interface reaches the exhaust port 2d to which the exhaust pipe 13 is connected. Since the gas-liquid interface is discharged to the outside of 2, the gas-liquid interface does not move downward and stays at the position of the exhaust port 2d to which the exhaust pipe 13 is connected. As a result, the pressure of the gas phase formed inside the tank 2 is kept constant at a state higher than the atmospheric pressure. For example, when the depth from the water surface to the exhaust port 2d to which the exhaust pipe 13 is connected is 3 m, the pressure of the gas phase described above is about 30 kPa (gauge pressure).

Further, if the solenoid valve 14a is opened instead of the solenoid valve 13a, the air supplied from the air supply pipe 7 to the tank 2 is exhausted when the gas-liquid interface reaches the exhaust port 2d to which the exhaust pipe 14 is connected. When the exhaust pipe 14 is discharged to the outside of the tank 2 through the pipe 14, the exhaust pipe 14 stays at the position of the connected exhaust port 2d, and the gas phase pressure formed inside the tank 2 opens the solenoid valve 13a. It is maintained at a higher level than that. For example, when the depth from the water surface to the exhaust port 2d to which the exhaust pipe 14 is connected is 6 m, the pressure of the gas phase described above is about 60 kPa (gauge pressure).

As described above, according to the gas melting device 1c, it is possible to easily adjust the pressure of the gas phase formed inside the tank 2 by changing the number of the exhaust ports 2d and the installation location. Further, in the gas melting device 1c, it is not necessary to install a sensor for detecting the position of the gas-liquid interface, a control mechanism for maintaining the gas phase formed inside the tank 2 at a constant pressure, and the like. , Manufacturing cost can be reduced. Further, in the gas dissolving device 1c, the gas inside the tank 2 is constantly replaced and the composition is kept constant, so that the concentration of the gas dissolved in the treated water discharged from the drain port 2b fluctuates. hard.

Further, in the gas melting device 1c, when the amount of oxygen supplied from the branch pipe 12 to the air supply pipe 7 is increased by adjusting the opening degree of the solenoid valve 12a, oxygen in the gas phase formed inside the tank 2 is charged. Partial pressure increases. For example, in the air containing 20% oxygen, the saturation amount of oxygen under atmospheric pressure of 20 degrees is 8.8 mg / L, but in the gas dissolving device 1c, the oxygen contained in the air forming the gas phase When the ratio of oxygen is increased to 30%, the saturation amount of oxygen becomes 1.5 times the above value. As described above, according to the gas dissolving device 1c, since it is easy to adjust the partial pressure of oxygen contained in the gas phase formed inside the tank 2, the amount of dissolved oxygen in the treated water discharged from the drain port 2b Can be efficiently increased.

The present invention is applicable not only to oxygen but also when it is necessary to dissolve a desired gas in a desired liquid.

1a to 1c ... Gas dissolution device 2 ... Tank 2a ... Water supply port 2b ... Drain port 2c ... Water level sensor 2d ... Exhaust port 3 ... Water supply pipe 4 ... Drain pipe 4a ... Pressure adjustment valve 5 ... Water supply pump 6 ... Piping 7 ... Air supply pipe 7a ... Solenoid valve 8 ... Swirling flow generator 9 ... Main body 9a ... Peripheral wall 9b ... Ejection hole 10 ... Introduction hole 11 ... Air supply pump 12 ... Branch pipe 12a ... Electromagnetic valve 13, 14 ... Exhaust pipe 13a, 14a ... Solenoid valve fs ... swirling flow f'... membranous flow

Claims (4)

A tank in which a water supply port and a drainage port are provided at the upper and lower parts, and a gas phase consisting of a gas having a pressure higher than the atmospheric pressure is formed inside.
A water supply pipe for supplying water to the inside of this tank through the water supply port,
A water supply pump for delivering the water to this water supply pipe,
The piping for supplying the water to this water supply pump and
An air supply pipe for supplying the gas to the tank and
A drainage pipe for draining the treated water collected in the lower part of the tank from the drainage port,
A swirling flow consisting of a membrane thinner than a membrane formed by water that is installed in the tank and is supplied from the water supply pipe through the water supply port and is ejected into the gas phase and travels linearly. A gas melting device comprising a swirling flow generator, which forms a. It is elongated in the vertical direction and is installed so that at least a part of it is submerged in water. It also has water supply ports and drainage ports at the top and bottom, respectively, and a gas phase consisting of gas with a pressure higher than atmospheric pressure. The tank formed inside and
A water supply pipe for supplying water to the inside of this tank through the water supply port,
A water supply pump for delivering the water to this water supply pipe,
The piping for supplying the water to this water supply pump and
An air supply pipe for supplying the gas to the tank and
The air supply pump installed in this air supply pipe and
An exhaust port provided on the side surface of the tank so as to be above the drain port and below the water surface.
The exhaust pipe connected to this exhaust port and
The valve installed in this exhaust pipe and
From a film formed by water that is installed in the tank above the exhaust port and ejects the water supplied from the water supply pipe through the water supply port into the gas phase and travels linearly. A gas melting device comprising a swirling flow generator that forms a swirling flow composed of a thin film. The swirling flow generator
It has a hollow part and is substantially rotationally symmetric, and has a main body formed so as to reduce the diameter toward one of the axial directions of the rotational symmetry axis.
This body is
An introduction hole connected to the water supply pipe is provided so as to open in the peripheral wall portion in the tangential direction, and at the same time.
The gas dissolving apparatus according to claim 1 or 2, wherein a ejection hole is provided in the reduced diameter portion so as to open in the axial direction of the axis of rotational symmetry. The process of forming a gas phase consisting of a gas with a pressure higher than atmospheric pressure inside a closed tank,
A gas dissolution method comprising a step of supplying water to the inside of the tank and forming a thin film-like swirling flow composed of the water in the gas phase.

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