JPH0262300B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for continuously dissolving and transferring a gas in a liquid (solvent) in an atmosphere with a pressure higher than atmospheric pressure, and the method. The present invention relates to a device that can be used effectively.

[Prior Art] Methods and devices for dissolving gas in liquid under pressure, that is, under pressure equal to or higher than atmospheric pressure, include the following (a):
Those shown in ~(c) are known.

(a) Equipment consisting of pumps, compressors, pressure tanks, etc. This device uses a compressor in a pressure vessel containing a liquid to pump gas into it.
The liquid and gas are retained in the pressure vessel, and the gas is dissolved from the liquid surface in an almost static state.

(b) A device in which a stirrer is attached to the pressure tank of (a) above to promote the dissolution of gas.

(c) A device in which a filler such as a baffle plate is installed in the pressure tank of (a) or (b) above.

[Problems to be Solved by the Invention] According to the melting device (a), the contact area of gas and liquid in the pressure tank is very small, and the melting is performed in a static state. For this reason, there was a problem in that the gas-liquid dissolution efficiency was low and the time required for dissolution was long unless the pressure tank was made considerably large. Also, like the dissolving device in (b) above,
Providing a stirrer in the pressure tank will somewhat accelerate dissolution, but the gas will still dissolve only at the liquid level. Furthermore, a new power source must be provided to drive the agitator, and a seal structure must be provided between the pressure tank and the agitator.
Theoretically, it would be possible to disperse the gas in the liquid in the tank by applying a strong stirring force using a special rotating blade, but if only the dissolved liquid is in the tank, leaving undissolved gas behind. In order to extract it outside, it would be necessary to install yet another tank, which is not practical. Further, according to the dissolving device (c) above, the dissolving efficiency is slightly improved compared to the devices (a) or (b), but the above-mentioned problems are not solved.

Furthermore, in order to statically dissolve gas using the conventional devices described in (a) to (c) above, it is necessary to control the level of the liquid in the pressure tank. Therefore, it is necessary to provide equipment such as a means to adjust the amount of gas introduced into the pressure tank and a gas vent valve to separate undissolved gas in the pressure tank, making the entire device complicated and expensive. There was a problem with this.

[Purpose of the Invention] The present inventor has discovered that in order to efficiently dissolve gas in liquid, it is generally necessary to lengthen the contact time of gas and liquid and increase the chance of contact between gas and liquid. They came up with the idea that it would be sufficient to make the gas present in excess in the liquid and provide stirring. That is, according to the conventional apparatus and method described above,
It was thought that stirring could not be achieved due to the presence of an excessive amount of finely divided gas in the pressure tank.
Therefore, the present inventor has developed a method for dissolving and transferring gas that can efficiently dissolve gas in liquid by increasing the contact time and chance of contact between gas and liquid by stirring the liquid with an excessive presence of fine air bubbles. The purpose of this invention was to provide a device useful for this method.

[Means for Solving the Problems] In order to achieve the above-mentioned object and solve the conventional problems, a method for dissolving and transferring gas according to the present invention includes pumping gas and liquid to a cyclone, and transporting the fluid into the cyclone. The gas is dispersed and dissolved in the liquid by stirring and staying there, and at the same time, the gas and liquid are separated by centrifugal force, and the dissolved liquid is extracted to the outside from the underflow port of the cyclone, and the liquid containing excess dispersed gas is removed. The fluid is extracted from the overflow port of the cyclone and passed through the injector, and the injector sucks in gas using a suction force that corresponds to the kinetic energy of the fluid passing through the injector. At the same time, additional liquid is added to this fluid, and the fluid is forced into the cyclone again. It is characterized by the fact that Further, the gas dissolving and transferring device according to the present invention includes a pump for pumping gas and liquid, internally stirring and retaining the gas and liquid supplied from the pump, dispersing and dissolving the gas in the liquid, and centrifuging the gas and liquid. A cyclone in which gas and liquid are separated by force and the dissolved liquid is extracted from the underflow port, and a liquid containing excess dispersed gas extracted from the cyclone passes through it, and a suction force is generated depending on the kinetic energy of the passing fluid. The pump is characterized by comprising an injector for sucking gas into the inside of the pump, and a liquid inlet connected to an inlet of the pump together with an outlet of the injector.

[Function] When gas and liquid are sucked into the pump, the gas is finely pulverized inside the pump, dispersed in the liquid, and a portion is dissolved in the liquid. The fluid discharged from the pump flows into the cyclone, and the fluid is stirred by rotational movement within the cyclone, and the gas is further dissolved into the liquid by stirring and retention. Within the cyclone, the liquid containing more undissolved gas collects in the center of the cyclone due to centrifugal force, while the fluid containing dissolved gas is drawn out to the outside through the liquid outlet. The liquid containing undissolved gas is then extracted from the cyclone, supplied to the injector, and passes through the injector toward the outlet. At this time, a suitable amount of gas is sucked into the injector by a suction force depending on the kinetic energy of the fluid passing through the injector, and the gas is dispersed in the fluid. Then, the fluid that has passed through the injector joins with the liquid supplied from the liquid inlet, enters the suction port of the pump, is compressed again, and is sent to the cyclone. That is,
A liquid containing undissolved gas is circulated between the cyclone injector and the pump, and the injector self-controls the intake air amount according to the proportion of bubbles contained in the liquid. Therefore, according to the present invention, there are many chances of contact between gas and liquid, and the contact area is also large, so that gas can be efficiently dissolved in a short time.

[Example] An example of the present invention will be described with reference to FIGS. 1 to 6.

FIG. 1 shows a gas dissolving and transferring device 1 according to this embodiment.
2 is a schematic diagram showing a pump, in which 2 is a pump for dispersing and dissolving gas in a liquid and pumping the fluid to a cyclone 3, which will be described later. In general, in a normal centrifugal pump, if the proportion of gas in the inflowing fluid becomes large, vibrations, abnormal noises, abnormal wear of the rotating blades, etc. may occur, and the fluid may become unable to be discharged or the discharge may become intermittent. This may cause inconveniences such as getting tired. The inventors of the present invention believe that the cause of such inconvenience lies in the shape of the fluid passage in the impeller section, and further confirmed that the cause is that the cross-sectional area of the fluid passage is larger on the outlet side than on the inlet side. Therefore, the pump 2 used in this embodiment
As will be described later, the impeller section is structured so that it can pump a large amount of gas together with liquid. 4 shown in FIG. 2a is an impeller body composed of a main plate 6 having a boss 6a to which a drive shaft 5 is attached, and a plurality of blades 7 provided on one side of the main plate 6. be. A disk-shaped side plate 8 having a hole 8a formed in the center is fixed to the blades 7 of the impeller main body 4, forming an impeller 9. As shown in FIG. 2a, the blades 7 have a claw-shaped cross-sectional shape curved into an arc, and each blade 7, the side surface of the main plate 6, and the inner surface of the side plate 8 form a plurality of blades. A fluid passage 1 is configured.
Unlike the fluid passage in a normal centrifugal pump, this fluid passage 10 has a larger cross-sectional area on the elliptical inlet 11 side and a smaller cross-sectional area on the elliptical outlet 12 side, as shown in Fig. 2b. The walls are smooth with no corners. However, depending on the manufacturing cost and other considerations, the cross-sectional shape of the fluid passage 10 may have corners such as a rectangular shape. In addition, both cross-sectional areas are determined by the fluid pressure at the outlet 12 so that the apparent flow velocity of the fluid in the fluid passage 10 (the value obtained by dividing the apparent volume of fluid flowing within a certain period of time by that time) is constant. Set based on the mixing ratio of gas and liquid. For example, when trying to mix and transfer 6 m ³ /h of water and 2 m ³ /h of air, if the pressure of the fluid at the outlet 12 is 5 Kgf/cm ² , the volume of the gas will be compressed to about 1/5. The cross-sectional area A on the inlet 11 side and the cross-sectional area A' on the outlet 12 side can be determined by the following equation.

6+2/A=6+0.4/A' Next, the discharge port 13 of the pump 2 is connected and communicated with the cyclone 3. The cyclone 3 is a fluid tank for stirring and retaining the fluid supplied from the pump 2 under pressure to dissolve gas in the liquid. As shown in FIG. 3, this cyclone 3 has a cylindrical upper half 3a and a substantially conical lower half 3b, but the cone angle of the lower half 3b has been determined experimentally.
Good results can be obtained by setting the angle to around 20°. The pipe P1 led from the discharge port 13 of the pump 2 is
It is connected and communicated in a tangential direction to the side surface of the upper half 3a via the valve V1 and the pressure gauge G1, and the cross-sectional shape of the connection part is preferably a rectangular shape elongated along the circumferential direction of the cyclone 3. In addition, a circulating fluid outlet 1 as an overflow port is provided in the center of the upper half 3a.
4 is provided, and the pipe P2 is connected and communicated with the pipe P2.
When the cyclone 3 is placed vertically as in this embodiment, it is preferable that the pipe P2 connected to the circulating fluid outlet (overflow port) 14 not protrude into the inside of the cyclone 3. At the lower end of the cyclone 3, a solution outlet 15 is provided as an underflow port for dissolving solution. A pipe P3 is connected and communicated with this liquid outlet (underflow port) 15, and a pipe V2 is provided in the pipe P3. Further, this cyclone 3 is provided with a pressure gauge G2.

The cyclone 3 of this embodiment is installed vertically, but when a cyclone 3' having approximately the same shape as this is used horizontally, the circulating fluid outlet (overflow port) is It is preferable to provide a gently sloped cone 16 between the cone 14 and the pipe P2. Furthermore, if it is desired to downsize the entire device or to keep manufacturing costs low, a cylindrical cyclone 17 as shown in FIGS. 5a and 5b may be used. Such a cylindrical cyclone 17 has a smaller centrifugal force applied to the fluid than the cyclones 3 and 3', and therefore has a slightly inferior fluid separation property, but is effective when handling gases that are difficult to dissolve.

Next, a pipe P2 connected to the circulating fluid outlet (overflow port) 14 of the cyclone 3 is connected to the inlet 19 of the injector 18 via a flowmeter G3 and a valve V3. As shown in FIG. 6, the injector 18 is a pipe-shaped device with a passage in the center through which the fluid passes, and has a tapered shape in which the inner diameter is narrowed from the inlet 19 to the center where the throttle hole 21 is located. It is formed in a tapered shape in which the inner diameter increases from the central part to the outlet 20. A suction port 22 communicating with the throttle hole 21 is formed on the outer circumferential surface of the central portion. It is configured so that gas can be sucked into it. A check valve 23 is provided inside the suction port 22 to prevent fluid flowing from the inflow port 19 toward the outflow port 20 from being discharged from the suction port 22 to the outside. Further, a disk-shaped twisting blade 24 is rotatably provided at the inlet 19 of the injector 18.
In addition to stabilizing the gas suction force, the injector 1
The gas sucked into the chamber 8 can be effectively atomized. In addition, instead of such a disk-shaped twisting blade 24, a propeller-shaped blade with less pressure loss may be provided.

Next, a pipe P4 is connected to the suction port 22 of the injector 18. A valve V4 and a flow meter G4 are connected to the pipe P4, and the gas inlet 28 is open to gas at a predetermined pressure.
Further, a pipe P5 connected to the outlet 20 of the injector 18 is inserted into a T-pipe 26 connected to the suction port 25 of the pump 2 from one open end thereof. A pipe P6 is connected to the other open end of the T-pipe 26 via a valve V5, and the end of the pipe P6 serves as a fluid inlet 27.

Next, a method for dissolving and transferring gas using the apparatus configured as described above will be described.

The pump 2 is driven by a drive means (not shown), and liquid and gas are supplied to the pump 2. The liquid and gas sucked into the impeller part 9 are pressurized while moving through a fluid passage 10 having a smooth shape. The fluid passage 10 of the impeller part 9 in the pump 2 of this embodiment has a large cross-sectional area on the inlet 11 side through which the uncompressed fluid passes, and the outlet 12 through which the compressed fluid passes.
The side cross-sectional area is made smaller. Therefore, when a liquid and a gas, which is a compressible fluid, are pumped together, the apparent flow velocity of the fluid from the inlet 11 to the outlet 12 in the fluid passage 10 (the value obtained by subtracting the apparent volume of the fluid flowing within a certain period of time by that time) ) becomes constant, so
There are no regions of different pressures within the fluid passageway 10, and no harmful vortices are generated within the fluid passageway 10. In particular, in this embodiment, the wall surface of the fluid passage 10 has a smooth shape with no corners, so the resistance between the wall surface and the fluid is uniform in all parts, which reduces the possibility of abrasion of the wall surface. There is also no fear that a fluid vortex will occur in a particular part. In this way, the gas and liquid sucked into the impeller section 9 are smoothly transferred at a constant flow rate within the smooth-shaped fluid passage 10 without generating vortices, so that a considerable amount of gas can be pumped together with the liquid. Even if the pump 2 is in operation, no trouble such as abnormal noise or vibration occurs, and the wall surface of the fluid passage 10 does not wear abnormally. Then, in the impeller section 9, the sucked gas is pressurized and pulverized into fine pieces, dispersed and mixed in the liquid, and a part of the gas is dissolved in the liquid.

The fluid protruding from the pump 2 flows into the cyclone 3, and this fluid is stirred in the cyclone 3 while rotating vigorously under pressure, and the gas is further dissolved into the liquid by stirring and retention. In the cyclone 3, a large amount of liquid containing a large amount of undissolved bubble-like gas gathers in the center of the cyclone 3 due to centrifugal force. Additionally, gases that have become difficult to dissolve due to their association and increase in volume also gather in the center. On the other hand, the liquid containing dissolved gas (solubility) moves to the lower half 3b of the cyclone 3 while rotating, passes through the liquid outlet (underflow port) 15, and enters the valve V.
2 to an external destination (not shown). In this case, the amount of dissolved liquid coming out of the liquid outlet (underflow port) 15 is kept constant by adjusting the opening degree of the valve V2, etc. The pressure is kept constant.

The liquid containing the undissolved gas is extracted from the circulating fluid outlet (overflow port) 14 and supplied to the inlet 19 of the injector 18.
It passes through the inside toward the outlet 20. At this time,
Gas is sucked into the injector 18 from the suction port 22 by the kinetic energy of the passing fluid. The suction force of gas varies depending on the kinetic energy of the passing fluid, that is, the amount of gas contained in the fluid. For example, when the fluid extracted from the circulating fluid extraction port (overflow port) 14 contains a large amount of gas, the kinetic energy of the fluid is small, so the amount of fluid sucked into the injector 18 is small. Conversely, if the fluid contains almost no air,
A large amount of gas is sucked into the injector 18 by a strong suction force corresponding to the kinetic energy. In this way, in the device 1 of this embodiment, the amount of gas suction is self-controlled. And injector 1
The gas sucked in at step 8 is atomized in this injector 18 together with undissolved gas sent together with the liquid from the cyclone 3, and dispersed and mixed in the liquid. Further, in this embodiment, since the injector 18 is provided with the twisted blades 24, the gas suction state is stable.

Next, the fluid that has passed through the injector 18 is sent into the T-pipe 26 via the pipe P5. A predetermined amount of liquid is supplied into this T-tube 26 from a liquid inlet 27 . The fluid and the liquid newly supplied into the system join together in this T pipe 26 and are sent to the suction port 25 of the pump 2.

In this way, in this example, an appropriate amount of liquid is supplied into the system, and an appropriate amount of solution is transferred to the cyclone 3.
The pressure inside the equipment system is kept constant by drawing water from the tank. The injector 18 self-controls the intake air amount while circulating part of the fluid including undissolved fluid within the system, thereby efficiently dissolving the gas into the liquid. That is, the device 1 of this embodiment
Since the fluid is circulated, there are many chances of contact between the gas and liquid, and because the gas is repeatedly made fine in various places, the contact area between the gas and liquid is large, so it is possible to statically extract the gas only from the liquid surface. Gases can be dissolved more efficiently than conventional devices and methods that dissolve gases.

The gas dissolution and transfer device 1 as in this embodiment has a simple structure, so manufacturing costs can be reduced.
Furthermore, since the pump 2 uses an impeller portion 9 that is less prone to troubles such as abnormal wear, maintenance is easy. Therefore, the device 1 can be effectively used in various fields, and can be used not only for simply dissolving gas in liquid, but also for other purposes. That is, according to the device 1, part of the gas is dissolved in the liquid, and the remaining part is mixed into the liquid as fine dispersed bubbles. Therefore, by adjusting the amount of circulating fluid flowing into the injector 18, the amount of gas sucked into the injector 18, and the amount of dissolving liquid discharged from the cyclone 3 by operating valves, etc., the dissolved liquid can be dissolved in the liquid. The amount and ratio of dispersed bubbles mixed into the gas and liquid can be set arbitrarily. Gas dissolved in a liquid becomes bubbles and precipitates under atmospheric pressure, so if this device 1 is used in a wastewater flotation separation facility that utilizes such precipitated bubbles or the above-mentioned dispersed bubbles, it can be This is advantageous because the ratio and amount of dispersed bubbles and precipitated bubbles can be adjusted as desired.

Next, the results of testing the dissolving and transferring device 1 will be explained using a specific example. 3.7KW×2900rpm
A conventional centrifugal pump has a fluid passage 1 as described above.
Attach the impeller part 9 having 0. Cyclone 3 has an inner diameter of approximately 260 mm and an internal volume of 19 mm.
The injector 18 used had an inner diameter of about 10 mm at the entrance/exit part, a total length of about 50 mm, and an inner diameter of the throttle hole 21 of about 3 mm. It has been experimentally confirmed that the self-suction air amount of this injector 18 is 10 N/min when the inflow pressure of the injector 18 is 4.Kgf/cm ² and the same inflow rate is 1/min.

Here, air was selected as the gas and water was selected as the liquid, the gas inlet 28 was opened to the atmosphere, and the liquid inlet 27 was connected to a water tank (not shown), and the apparatus was operated under various conditions. As a result, the liquid (water) inflow rate was 100/min, and the average air suction rate was 2.5/min.
/min, cyclone internal pressure 4.5Kgf/cm ² , dissolved liquid withdrawal rate 100/min, when circulating liquid volume is only water
10, the following results were obtained. That is,
The amount of air that precipitates when the obtained solution is left under atmospheric pressure is 2.5%, and even if you operate all day and night in this state without adjusting the valves, the amount of dissolved solution and the air that precipitates from the solution will be 2.5%. No change was observed in the amount. However, the amount of air suction always fluctuated within the range of 0 to 10/min from the indicated value of the flowmeter G4.

From the above results, it was confirmed that with this device, the amount of air self-suction is automatically controlled, and a solution with a precipitated air amount of 2.5% can be continuously obtained with a residence time of 11.4 seconds.

In order to compare with the example of the test results mentioned above, the seventh
An example of operation will be shown in which a dissolving device as shown in the figure is configured and air is dissolved in water. This equipment system connects the cyclone 3 to a pressure tank 30 (capacity 240).
The discharge port 13 of the pump 2 and the inlet port 19 of the injector 18 are connected and communicated with the lower part of the pressure tank 30. Also, pressure tank 3
A dissolution liquid extraction port 31 is provided at the bottom of the 0.
A gas vent valve 32 is provided at the top. In the figure, G5 and G6 are flow meters, and G7 is a pressure gauge.

When such a device was operated under various conditions, the liquid (water) inflow rate was 60/min, the air suction rate was 4/min on average, the dissolved solution withdrawal rate was 60/min, and when the circulating liquid was only water, the rate was 10/min. /min, the result was that the amount of precipitated air was 2.5%. However, since this device does not automatically control the amount of intake air, excess air accumulates in the pressure tank 30. Therefore, the liquid level position in the pressure tank 30 is measured using a level meter (not shown), and the gas vent valve 32 is
Excess air had to be removed by manual operation. Furthermore, this example required a residence time of 4 minutes, and it was confirmed that the dissolution efficiency was extremely low compared to the previous example.

[Effects of the Invention] According to the method and device for dissolving and transferring gas according to the present invention, the pump and injector mainly use the pump and the injector to atomize the excess gas and disperse it in the liquid, and the cyclone mainly stirs and stagnates the fluid. This causes the gas to dissolve in the liquid. Further, the injector self-controls the intake air amount while circulating a part of the fluid containing undissolved gas within the system. Therefore, according to the present invention, there is an effect that gas can be efficiently dissolved in a liquid in a short time.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the device according to the present invention, FIG. Figure 3 a, b showing the shape of
are a plan view and a front view of the cyclone in the same embodiment, FIGS. 4a and 4b are views showing a horizontally installed cyclone,
Figures 5a and 5b are plan and front views showing other forms of the cyclone, Figure 6 is a sectional view of the injector in the same embodiment, and Figure 7 is constructed for comparison with the device of the same embodiment. FIG. 1 is an overall configuration diagram of a melting device having a pressure tank. 1... Gas dissolving and transferring device (device), 2... Pump,
3, 3', 17...Cyclone, 14...Circulating fluid outlet as an overflow port, 15...Dissolved liquid outlet as an underflow port, 18...Injector,
20...Injector inlet, 25...Pump suction port, 27...Liquid inlet.

Claims (1)

[Claims] 1. Gas and liquid are forced into a cyclone, and the fluid is stirred and retained in the cyclone to disperse and dissolve the gas in the liquid, while at the same time separating the gas and liquid by centrifugal force, The dissolved liquid is extracted to the outside from the underflow port of the cyclone, and the liquid containing excess dispersion gas is extracted from the overflow port of the cyclone and passed through the injector, using a suction force corresponding to the kinetic energy of the fluid passing through the injector. A method for dissolving and transferring gas, characterized in that the injector sucks the gas, further adds liquid to the fluid, and forces the cyclone to feed the gas again under pressure. 2. A pump that pumps gas and liquid under pressure, and a system that internally stirs and stirs the gas and liquid supplied from the pump.
A cyclone that disperses and dissolves the gas in the liquid by stagnation, separates the gas and liquid by centrifugal force, and extracts the dissolved liquid from the underflow port, and a cyclone that removes the excess dispersed gas extracted from the overflow port of the cyclone. an injector through which a contained liquid passes and which sucks gas into the interior with a suction force corresponding to the kinetic energy of the passing fluid; a liquid inlet connected to an inlet of the pump together with an outlet of the injector;
A liquid dissolving and transferring device characterized by comprising: