JP5372585B2 - Gas-liquid dissolution tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas-liquid dissolving tank which has a simple structure, a high dissolution rate of the gas to the liquid and a small pressure drop. <P>SOLUTION: The gas-liquid dissolving tank for dissolving the gas into the liquid under pressurization has a jet generating member to generate a jet on the tip and is provided with an interpolation tube for introducing a mixture of the gas and liquid into the inside of the tank, and a baffle plate arranged at the outflow direction of the jet. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a gas-liquid dissolution tank, and more particularly, to a gas-liquid dissolution tank of a pressurized water generator in a pressurized flotation process used in wastewater treatment or water treatment.

  In wastewater treatment and irrigation treatment, a levitating separation apparatus is used in which fine bubbles are mixed and adhered to a substance to be removed in the for-treatment water, for example, SS component and oil, and separated in a levitation tank by its buoyancy. In many cases, the substance to be removed in the water to be treated is flocified by adding a flocculant before mixing fine bubbles.

  As a method of generating fine bubbles, a method of generating fine bubbles is often used by reducing a pressurized liquid such as pressurized water in which a gas such as air is dissolved under pressure to a deep water pressure. Such a floating separation process using pressurized water is particularly referred to as a pressurized floating process. In the pressure levitation treatment, a large amount of fine bubbles can be supplied to the water to be treated, so that many bubbles can adhere to the floc in the water to be treated, the quality of the treated water is good, and There is an advantage that the processing speed can be set high, and it is widely adopted.

  The method of generating fine bubbles by dissolving air under pressure utilizes the fact that high pressure water can dissolve a large amount of air. A large amount of fine bubbles are generated.

  In general, an apparatus for preparing pressurized water includes a pressurized water pump, a compressor, a gas-liquid dissolution tank, and the like. In a state where water is pressurized to, for example, 0.3 to 0.6 MPa by a pressurized water pump or the like, air is supplied into the system by a compressor or the like to dissolve the air into water. Air that has not been dissolved in the gas-liquid dissolution tank is separated, and pressurized water in which the air is dissolved is supplied to the water to be treated.

  However, in reality, simply supplying air to high-pressure water does not sufficiently dissolve the air, so a dissolver is installed or a structure that promotes dissolution of air is provided inside the gas-liquid dissolution tank. Etc. are made.

  As an index for evaluating the degree of air dissolution, there is an air dissolution rate (%) with respect to the theoretical air dissolution amount (hereinafter sometimes simply referred to as “dissolution rate”), which is defined by Equation 1. The theoretical air dissolution amount in Equation 1 can be calculated from Henry's law.

  Examples of the dissolver include a line mixer (for example, see FIG. 8) and an ejector (for example, see FIG. 9). A line mixer, after mixing a gas such as air and a liquid such as water, is provided with a plate that creates a swirling flow in a direction parallel to the flow in the pipe, increasing the contact area of the gas and liquid, It works to promote gas dissolution.

  The ejector is installed in a part where a gas such as air and a liquid such as water are mixed, and a negative pressure is generated by narrowing the main pipe diameter, and air or other gas is self-supplied or press-fitted with a compressor or the like. The gas and liquid are brought into contact with each other vigorously to dissolve the gas.

  When using a dissolver such as a line mixer or ejector alone to dissolve air in water, the dissolution rate is limited to about 40 to 50% even if a large amount of air is blown. When the dissolution rate is 40 to 50% with the use of a single dissolver, the ratio of pressurized water to treated water (pressurized water ratio) is used to supply the treated water with a predetermined amount of bubbles necessary for flotation. Needs to be as large as 20 to 40%. For this reason, a pressurized water pump having a large capacity is required, and the running cost mainly including the initial cost and the power cost increases. The dissolution rate can be improved by using multiple dissolvers, such as combining an ejector and a line mixer, but the pressure loss in the dissolver increases, and a pressurized water pump with a capacity that allows for the pressure loss is necessary. This also increases initial costs and running costs.

  In some cases, the gas-liquid dissolution tank is used to promote air dissolution. Some gas-liquid dissolution tanks perform only air dissolution, and separation / exclusion of undissolved air is performed in another tank, and air dissolution and gas-liquid separation are performed in one tank. For example, the former type includes a gas-liquid dissolution tank 80 having a structure as shown in FIG. 10 described in Non-Patent Document 1, and a turbulence generated when a fluid under high pressure passes through a hole in a perforated plate. The gas is subdivided by the flow, and the gas-liquid contact area is increased to promote air dissolution. In the latter type, there is a gas-liquid dissolution tank 82 having a structure as shown in FIG. 11 described in Patent Document 1. First, the gas-liquid is vigorously mixed and brought into contact with a nozzle installed at the tank inlet to dissolve a certain amount of air. In this structure, the flow path is lengthened to sufficiently contact with air to promote air dissolution.

  When air is dissolved in water using a gas-liquid dissolution tank, those that do not have any internal filling structure need to take a long residence time of water (about 3 to 5 minutes) in order to obtain a predetermined air dissolution effect. In addition, since the tank volume is increased, the installation area and the manufacturing cost are increased. When the gas-liquid dissolution tank is structured as shown in FIGS. 10 and 11 and the method of promoting the dissolution of air into water is taken, the dissolution rate is about 60 to 70% with a small capacity of about 1 minute of water retention time. However, it is required to obtain a higher dissolution rate.

  Furthermore, the following two points can be considered as problems of the gas-liquid dissolution tank having the structure as shown in FIG. The first is that when a predetermined dissolution rate is to be obtained, a large pressure loss occurs because a multi-stage perforated plate is installed. Therefore, it is necessary to use a pressurized water pump that allows for the pressure loss. Secondly, it is necessary to arrange a gas-liquid separation tank separately from the gas-liquid dissolution tank, and as a result, a large installation area is required for the entire pressurized water production facility.

  Further, in the gas-liquid dissolution tank having the structure as shown in FIG. 11, the pressure loss is only at the nozzle at the tank inlet. However, since the internal structure of the tank is complicated, the manufacturing cost increases when a large apparatus is used, and the pressurized water is increased. When the raw water for use contains SS, it is expected that SS will accumulate in the tank over a long period of operation, and maintenance such as cleaning is required.

JP 2004-290803 A

Mooyoung Han, Tschung-il Kim, Sungwon Park, Youkun Jung, “The development of a generator to produce bubbles of tailored sizes”, The 5th International Conference on Flotation in Water and Wastewater Systems, pp. 1-7 (2007)

  An object of the present invention is to provide a gas-liquid dissolution tank having a simple structure, a high gas dissolution rate in a liquid, and a small pressure loss.

The present invention, a gas a gas-liquid dissolving tank for dissolving under pressure in the liquid, has a jet flow generating member causing jets to the tip, the mixture of gas and liquid for introduction into the interior of the tank An intubation tube, a draft tube having both ends open, and a baffle plate arranged in the outflow direction of the jet , wherein the draft tube is disposed so as to be submerged in the tank. The intubation is inserted from one opening of the draft tube so that the tip of the jet generating member is located in the draft tube, and the baffle plate is submerged outside the other opening of the draft tube. a gas-liquid mixing tank that will be arranged to.

Further, in the gas-liquid dissolving tank, Rukoto the jet is the insertion tube is arranged to occur substantially vertically upward are preferred.

  The gas-liquid dissolution tank preferably includes an exhaust pipe inserted from the upper part of the tank to the inside with a predetermined length and a valve connected to the exhaust pipe for adjusting the exhaust amount.

  In the present invention, a nozzle or an orifice for generating a jet flow is provided at the tip, and an internal intubation tube for introducing a mixture of gas and liquid into the tank and a baffle plate arranged in the flow direction of the jet flow are provided. A gas-liquid dissolution tank having a simple structure, a high gas dissolution rate in a liquid, and a small pressure loss can be provided.

It is a schematic block diagram which shows an example of the pressurized water manufacturing system which concerns on embodiment of this invention. It is the schematic which shows the structure of an example of the gas-liquid dissolution tank which concerns on embodiment of this invention. It is the schematic which shows the structure of an example of the baffle plate in the gas-liquid melt | dissolution tank which concerns on embodiment of this invention. It is the schematic which shows the structure of an example of the pipe | tube (draft tube) by which the both ends became the opening in the gas-liquid dissolution tank which concerns on embodiment of this invention. It is the schematic which shows the structure of the other example of the gas-liquid dissolution tank which concerns on embodiment of this invention. It is the schematic which shows the structure of the other example of the gas-liquid dissolution tank which concerns on embodiment of this invention. It is a schematic block diagram which shows the pressurized water manufacturing system used in the Example of this invention. It is the schematic which shows the structure of an example of the conventional line mixer. It is the schematic which shows the structure of an example of the conventional ejector. It is the schematic which shows the structure of an example of the conventional gas-liquid dissolution tank. It is the schematic which shows the structure of an example of the conventional gas-liquid dissolution tank.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

  FIG. 1 shows a schematic configuration of an example of a pressurized water production system according to an embodiment of the present invention. The pressurized water production system 1 includes a raw water tank 10, a pressurized water pump 12, a compressor 14, and a gas-liquid dissolution tank 16.

  In the pressurized water production system 1 of FIG. 1, the raw water tank 10 is connected to the lower side surface of the gas-liquid dissolution tank 16 through a pressurized water pump 12, a raw water flow rate adjustment valve 18, a raw water flow meter 26, and the raw water pipe 34. The compressor 14 is connected between the raw water flow meter 26 of the raw water pipe 34 and the gas-liquid dissolution tank 16 by an air pipe 36 or the like via the air flow rate adjusting valve 20 and the air flow meter 28. A pressurized water pipe 38 is connected to the lower part of the gas-liquid dissolution tank 16 via a pressurized water flow meter 30 and a pressure reducing valve 22. An exhaust pipe 40 is connected to the upper part of the gas-liquid dissolution tank 16 via an exhaust adjustment valve 24. A tank pressure gauge 32 is installed above the gas-liquid dissolution tank 16.

  In the pressurized water production system 1, liquid such as water (raw water) from the raw water tank 10 is pressurized by the pressurized water pump 12 through the raw water pipe 34, and the flow rate is adjusted by the raw water flow rate adjustment valve 18. A gas such as air pressurized by the compressor 14 is adjusted in flow rate by the air flow rate adjusting valve 20 through the air pipe 36 and mixed with liquid such as water in the raw water pipe 34. The mixture of water and air is supplied to the inside of the gas-liquid dissolution tank 16 from the lower side surface of the gas-liquid dissolution tank 16 through the raw water pipe 34. Inside the gas-liquid dissolution tank 16, after air is dissolved in water under pressure, the pressurized water is discharged from the lower part of the gas-liquid dissolution tank 16 through the pressurized water pipe 38, and the condensed water is used as the pressurized water in the pressure levitation process. To be supplied. When the pressurized water passes through the pressure reducing valve 22, it is released to a deep water pressure, and for example, fine bubbles on the order of micrometers are generated. On the other hand, a gas such as undissolved air is discharged from the upper part of the gas-liquid dissolution tank 16 through the exhaust pipe 40.

  FIG. 2 shows an example of the structure of the gas-liquid dissolution tank 16 according to this embodiment. The gas-liquid dissolution tank 16 includes a tank body 42 and a nozzle or orifice 44 (hereinafter, “nozzle or orifice 44” may be simply referred to as “nozzle 44”), which is a jet generating member that generates a jet. An intubation tube 46 is provided at the tip for introducing a gas and liquid mixture into the tank, and a baffle plate 48 is arranged in the jet flow direction. The gas-liquid dissolution tank 16 adjusts the amount of exhaust gas such as undissolved air that stays in the upper part of the tank so as to maintain the tank internal pressure and the water level within a predetermined range, and a draft tube 50 that is an open tube at both ends. An exhaust pipe 40 and an exhaust adjustment valve 24 may be provided as an exhaust amount adjustment mechanism.

  In the gas-liquid dissolution tank 16, the internal intubation 46 connected to the raw water pipe 34 in FIG. 1 is inserted from the lower side surface of the tank body 42. The inner tube 46 rises in a substantially vertical upward direction near the center of the lower surface of the tank, and has a nozzle 44 at the tip. The nozzle 44 is disposed so as to be submerged. A draft tube 50 is disposed so as to surround the tip portion of the nozzle 44, and a baffle plate 48 is disposed in the outflow direction of the jet. The baffle plate 48 is disposed so as to be submerged. The leading end, which is the outlet of the nozzle 44, is located inside the draft tube 50, and the baffle plate 48 and the draft tube 50 are not in contact with each other. The exhaust pipe 40 is inserted from the upper part of the tank to the inside with a predetermined length, and the exhaust pipe 40 is provided with an exhaust adjustment valve 24 for adjusting the exhaust amount. A pressurized water pipe 38 is connected to the lower part of the gas-liquid dissolution tank 16.

  The mixture of water and air supplied through the raw water pipe 34 in FIG. 1 is supplied from the lower side surface of the gas-liquid dissolution tank 16 into the tank through the inner tube 46. The mixture of water and air is ejected as a jet directed substantially vertically upward at the outlet of the nozzle 44 installed at the tip of the inner intubation tube 46. At that time, due to the turbulent flow generated at the outlet of the nozzle 44, the air becomes fine bubbles, the gas-liquid contact area increases, and the dissolution of the air into the water proceeds. Further, when the jet collides with the baffle plate 48, the bubbles are divided, and the gas and liquid are mixed and contacted, and the dissolution of air into water further proceeds. Furthermore, since a negative pressure is generated near the outlet of the nozzle 44, the water once dissolved in air is drawn again near the outlet of the nozzle 44 in the tank and comes into contact with the fine bubbles near the outlet of the nozzle 44. The dissolution of air is further promoted, resulting in a high air dissolution rate. The still undissolved air is adjusted by the exhaust pipe 40 having the exhaust adjustment valve 24 and discharged out of the tank. The water in which the air is sufficiently dissolved flows out from the pressurized water pipe 38 provided in the lower part of the tank as pressurized water, and is supplied to the condensed water through the pressure reducing valve 22 in FIG. When passing through the pressure reducing valve 22, it is released to a deep water pressure, and for example, fine bubbles on the order of micrometers are generated.

  As described above, the gas-liquid dissolution tank 16 according to the present embodiment has the nozzle or orifice 44 attached to the tip of the inner cannula 46 for introducing a mixture of gas and liquid into the tank, and jets the gas-liquid into the tank. In addition, a baffle plate 48 that is submerged in water is provided at the tip of the jet, and the jet stream is violently collided with the baffle plate 48.

  Further, in the present embodiment, the tank is provided with the draft tube 50 having both ends opened, the tip portion serving as the outlet of the nozzle 44 is located inside the draft tube 50, and the baffle plate 48 and the draft tube are disposed. 50 is arranged so as not to contact. As described above, since a negative pressure is generated near the outlet at the tip of the nozzle 44, the water once dissolved is drawn again near the outlet of the nozzle 44 in the tank. The flow that hits the baffle plate 48 returns from the inside of the draft tube 50 to the outside and also inside as shown in FIG. 2 with the tube wall of the draft tube 50 as the center, and a circulating flow is generated. The water that has flowed into the draft tube 50 again is mixed with the air ejected in the vicinity of the nozzle 44 and recontacts with the air. By this flow, the number of times of contact between the water in the tank and the fine bubbles at the outlet of the nozzle 44 is increased, and the dissolution of air is further promoted. The still undissolved air is adjusted by the exhaust pipe 40 having the exhaust adjustment valve 24 and discharged out of the tank.

  Furthermore, in the present embodiment, an exhaust pipe 40 that is an exhaust pipe that is inserted from the upper part of the tank to the inside with a predetermined length, and an exhaust adjustment valve 24 that is connected to the exhaust pipe 40 and adjusts the exhaust amount is provided. Prepare. Thereby, the water level and pressure in the tank can be kept as constant as possible, and the air dissolution effect can be stably obtained.

  The gas-liquid dissolution tank 16 according to the present embodiment can separate and discharge undissolved air, and has a simple structure with a small capacity and a higher dissolution rate than a conventional gas-liquid dissolution tank. The manufacturing cost of the liquid dissolution tank can be reduced, and the installation area of the gas-liquid dissolution tank that occupies a large proportion of the installation area required for the pressurized water production system can be reduced.

  Dissolution rate is about 40 to 50% by a method using a dissolver such as the above line mixer (FIG. 8) or ejector (FIG. 9), and dissolution in a gas-liquid dissolution tank having an internal structure as shown in FIGS. While the rate is about 50 to 70%, in the gas-liquid dissolution tank 16 according to the present embodiment, the dissolution rate is 75% or more, and when the draft tube 50 is installed, the air is dissolved at a dissolution rate of 80% or more. Can do. As a result, a predetermined amount of bubbles can be supplied to the coagulated water in the pressure levitation process with a small amount of pressurized water, so that the capacity of the pressurized water pump, compressor, etc. can be reduced, thereby reducing initial costs and running costs. be able to.

  In addition, since the gas-liquid dissolution tank 16 according to the present embodiment has a simple structure, it is less likely to accumulate SS and the like, and maintenance is easier than the gas-liquid dissolution tank having the internal structure as shown in FIG. is there.

  The jet direction of the gas and liquid into the tank by the nozzle or orifice 44 is not particularly limited as long as the jet flow collides with the baffle plate 48 to cause gas-liquid mixing and contact. To the baffle plate 48, it may be performed in a substantially vertical upward direction as shown in FIG. 2, may be performed in a substantially horizontal direction as shown in FIG. 5, or may be performed in a substantially vertical downward direction as shown in FIG. You may go in the direction. The gas-liquid dissolution tank 16 of FIGS. 5 and 6 also has a nozzle or orifice 44 for generating a jet at its tip, an inner tube 46 for introducing a mixture of gas and liquid into the tank, and a jet flow direction. And a baffle plate 48 disposed therein.

  In the gas-liquid dissolution tank 16 in FIG. 5, the internal intubation 46 connected to the raw water pipe 34 in FIG. 1 is inserted in a substantially horizontal direction from the vicinity of the center of the side surface of the tank body 42. A nozzle 44 is provided at the distal end of the inner tube 46. The nozzle 44 is disposed so as to be submerged. A draft tube 50 is disposed so as to surround the tip portion of the nozzle 44, and a baffle plate 48 is disposed in the outflow direction of the jet. The baffle plate 48 is disposed so as to be submerged. The leading end, which is the outlet of the nozzle 44, is located inside the draft tube 50, and the baffle plate 48 and the draft tube 50 are not in contact with each other. The exhaust pipe 40 is inserted from the upper part of the tank to the inside with a predetermined length, and the exhaust pipe 40 is provided with an exhaust adjustment valve 24 for adjusting the exhaust amount. A pressurized water pipe 38 is connected to the lower part of the gas-liquid dissolution tank 16.

  Further, in the gas-liquid dissolution tank 16 of FIG. 6, the internal insertion tube 46 connected to the raw water pipe 34 of FIG. 1 is inserted from the upper side surface of the tank body 42. The inner intubation 46 falls substantially vertically downward near the center of the upper surface of the tank, and has a nozzle 44 at the tip. The nozzle 44 is disposed so as to be submerged. A draft tube 50 is disposed so as to surround the tip portion of the nozzle 44, and a baffle plate 48 is disposed in the outflow direction of the jet. The baffle plate 48 is disposed so as to be submerged. The leading end, which is the outlet of the nozzle 44, is located inside the draft tube 50, and the baffle plate 48 and the draft tube 50 are not in contact with each other. The exhaust pipe 40 is inserted from the upper part of the tank to the inside with a predetermined length, and the exhaust pipe 40 is provided with an exhaust adjustment valve 24 for adjusting the exhaust amount. A pressurized water pipe 38 is connected to the lower part of the gas-liquid dissolution tank 16.

  As described above, even when the jet direction of the gas and liquid into the tank by the nozzle 44 is substantially horizontal (FIG. 5) or substantially vertically downward (FIG. 6), the same effect as the substantially vertically upward (FIG. 2) is obtained. However, the substantially vertical upward direction as shown in FIG. 2 is preferable from the viewpoint that undissolved air can be reliably separated.

  The gas-liquid dissolution tank 16 according to the present embodiment is for dissolving a gas into a liquid under pressure and for separating an undissolved gas from the liquid, and performs gas dissolution and gas-liquid separation in one tank. However, a separation means such as a gas-liquid separation tank for separately dissolving undissolved gas from the liquid by dissolving the gas in the liquid under pressure using the gas-liquid dissolution tank 16 according to the present embodiment. Gas-liquid separation may be performed by providing the Air is usually used as the gas, and water is usually used as the liquid. Pressurized flotation treated water or the like may be used as water (raw water) to be pressurized water.

  Mixing of a gas such as air and a liquid such as water may be performed by supplying air from a compressor or the like in the rear path of the pressurized water pump 12 as shown in FIG. You may supply to water. As the pressurized water pump 12, for example, a spiral pump may be used.

  The tank main body 42 in the gas-liquid dissolution tank 16 is usually in a shape having a straight body portion 52.

  The residence time in the gas-liquid dissolution tank 16 is, for example, 30 seconds to 1 minute.

  The jet generating member that generates the jet is not particularly limited as long as it generates the jet, and for example, a nozzle, an orifice, or the like may be used. A pressure loss between the inlet and the outlet is preferably 0.05 MPa or more from the viewpoint of generating a jet and easily generating fine bubbles.

  The arrangement position of the nozzle or orifice 44 is such that the distal end which is the outlet of the nozzle or orifice 44 is from the end where the inner tube 46 of the straight body 52 is inserted to the straight body from the viewpoint of effective use of the internal volume. It is preferable that they are arranged so as to fall within a range of 50% or less of the length of the portion 52. When the draft tube 50 is provided, the tip of the nozzle or orifice 44 may be positioned inside the draft tube 50. From the viewpoint of effective use of the internal volume, the tip of the nozzle or orifice 44 is connected to the draft tube 50. It is preferable that the end portion on the side where the intubation tube 46 is inserted is disposed at a position of 50% or less of the entire draft tube 50.

  The baffle plate 48 is not particularly limited as long as gas-liquid mixing is caused by the collision of the jet flow. For example, a baffle shape as shown in FIG. 3 may be used. The baffle plate 48 is fixed to the inside of the tank body 42 of the gas-liquid dissolution tank 16 by, for example, the support member 54.

  The arrangement position of the baffle plate 48 is not particularly limited as long as the baffle plate 48 is disposed so as to be submerged in the direction perpendicular to the jetting direction of the jet flow. It is preferable to be arranged so that it is within a range of 30% or less of the length of the straight body portion 52 from the end portion on the side where the is installed. In the case of the form of FIG. 2, it is preferable to arrange so as to be submerged near the water surface.

  The size of the baffle plate 48 is in the range of 25 to 80% of the inner diameter of the straight body portion 52 of the tank body 42 from the viewpoint that most of the jet flow from the nozzle 44 hits the baffle plate 48. It is preferable. When the draft tube 50 is provided, it is preferably within the above range and larger than the inner diameter of the draft tube 50.

  The draft tube 50 is a tube having openings at both ends, and usually has a cylindrical shape as shown in FIG. The draft tube 50 is fixed to the inside of the tank main body 42 of the gas-liquid dissolution tank 16 by a support member 56, for example.

  The length of the draft tube 50 is preferably in the range of 50 to 80% (1/2 to 4/5) of the length of the straight body portion 52 of the tank body 42 from the viewpoint that a circulating flow is easily generated. .

  The inner diameter of the draft tube 50 is preferably in the range of 25 to 75% (1/4 to 3/4) of the inner diameter of the straight body portion 52 of the tank body 42 from the viewpoint that a circulating flow is easily generated.

  The draft tube 50 may be disposed so as not to contact the baffle plate 48, but the end of the draft tube 50 on the baffle plate 48 side of the draft tube 50 is located on the straight body portion 52 from the viewpoint of easy circulation. It is preferable to be disposed so as to fall within a range of 5 to 20% of the length of the straight body portion 52 from the end portion on the baffle plate 48 side.

  The exhaust amount adjustment mechanism may be any mechanism that adjusts the exhaust amount of undissolved air or the like that stays in the upper part of the tank so as to maintain the internal pressure and water level of the gas-liquid dissolution tank 16 within a predetermined range. There is no particular limitation. For example, the exhaust amount adjusting mechanism is an exhaust pipe 40 that is an exhaust pipe inserted from the upper part of the gas-liquid dissolution tank 16 into a predetermined length and a valve that is connected to the exhaust pipe 40 and adjusts the exhaust amount. And an exhaust adjustment valve 24. In this case, if undissolved air stays in the vicinity of the upper water surface in the tank, the air is discharged from the exhaust pipe 40, and when the air is discharged to some extent, the water surface rises and the discharge of air stops. Thereby, undissolved air can be discharged | emitted, suppressing the fluctuation | variation of the internal pressure and water level in a tank. From the viewpoint of securing the gas-liquid separation area, it is preferable that the lower end portion of the inserted exhaust pipe 40 is disposed below the upper end of the straight body portion. A level switch or the like may be used as the displacement adjustment mechanism.

  The gas-liquid dissolution tank 16 according to the present embodiment can be used for preparing pressurized water in a pressurized flotation process used in, for example, waste water treatment or water treatment. In addition, it can be used for ozone dissolution.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

<Example 1 and Comparative Examples 1 and 2>
A comparative experiment was conducted using the pressurized water production system shown in FIG. Air is supplied to the raw water from the raw water tank 60 from the compressor 66 in the raw water pipe 64 on the downstream side of the pressurized water pump 62, and the gas-liquid dissolution tank 16 having the internal structure of FIG. The gas-liquid dissolution tank 80 having the structure of FIG. 11 and the gas-liquid separation tank 84, the gas-liquid dissolution tank 82 having the structure of FIG. The water flow to each tank was performed for each series using the inlet channel switching valve 68 and the outlet channel switching valve 70.

(Common experimental conditions)
Raw water: Pressurized levitated treated water SS 20mg / L
Raw water flow rate: 6m ³ / hr
Air supply amount: 1.8 m ³ / hr (gas-liquid mixture ratio: 30%)
Tank volume: 100L
Tank residence time: 1 min
Tank inlet pressure: 0.55 MPa
Water temperature: 20 ° C

  Under the above conditions, taking into consideration the operation of the actual machine, 60 sets (total 1200 hours) of intermittent water flow were performed with 10 hours of operation and 2 hours of stop being one set, and the air dissolution rates in each tank internal structure were compared. The tank inlet pressure is set by a tank inlet pressure gauge 72 installed on the upstream side of the inlet flow switching valve 68, and the tank outlet pressure is set between each tank outlet and the outlet flow switching valve 70. 74. As shown in FIG. 7, the air dissolution rate was measured at a sampling point on the upstream side of the pressure reducing valve 76 on the downstream side of the outlet flow path switching valve 70. Further, the state of pressurized water at the outlet of the pressure reducing valve 76 was observed.

  Table 1 summarizes the results of the comparative experiments. When comparing the air dissolution rate and the theoretical value air dissolution rate (hereinafter, dissolution rate), the gas-liquid dissolution tank of Example 1 was able to obtain the highest air dissolution rate and dissolution rate. On the other hand, regarding the pressure loss, the gas-liquid dissolution tank of Example 1 was almost the same as the gas-liquid dissolution tank of Comparative Example 2, but smaller than 0.1 MPa compared with the gas-liquid dissolution tank of Comparative Example 1 It became. When the same amount of water is passed through the gas-liquid dissolution tank, the pressurized water pump requires a head with a pressure loss added to the gas-liquid dissolution tank, so the pressure is higher than that of the gas-liquid dissolution tank of Comparative Example 1. The gas-liquid dissolution tank of Example 1 with a small loss can use a pressurized water pump having a lower capacity than the gas-liquid dissolution tank of Comparative Example 1, and the initial cost and running cost can be reduced accordingly. In addition, the initial cost is further reduced because a separate gas-liquid separation tank is not required.

  In the comparison between the gas-liquid dissolution tank of Example 1 and the gas-liquid dissolution tank of Comparative Example 2, the pressure loss is almost the same, but the dissolution rate of the gas-liquid dissolution tank of Example 1 exceeds 15% or more. . Considering to supply a certain amount of bubbles to the condensed water, the gas-liquid dissolution tank of Example 1 having a high air dissolution amount can suppress the air supply amount compared to other structures, and the size of the compressor can be reduced. Therefore, initial cost and running cost can be reduced.

  In continuous water flow for 1200 hours, high-concentration SS flowed out from the outlet of the pressure reducing valve in the gas-liquid dissolution tank of Comparative Example 2 when the apparatus was started for 1120 hours. This is because SS is accumulating in a complicated path in the tank, and it has been found that maintenance such as periodic cleaning is required, leading to an increase in running cost. In contrast, the gas-liquid dissolution tank of Example 1 was able to supply pressurized water with good water quality even during intermittent operation for 1200 hours.

  1 Pressurized water production system 10, 60 Raw water tank, 12, 62 Pressurized water pump, 14, 66 Compressor, 16, 80, 82 Gas-liquid dissolution tank, 18 Raw water flow adjustment valve, 20 Air flow adjustment valve, 22, 76 Pressure reducing valve, 24 Exhaust adjustment valve, 26 Raw water flow meter, 28 Air flow meter, 30 Pressurized water flow meter, 32 Tank pressure gauge, 34, 64 Raw water piping, 36 Air piping, 38 Pressurized water piping, 40 Exhaust piping, 42 Tank body, 44 Nozzle or Orifice, 46 Inner tube, 48 Baffle plate, 50 Draft tube, 52 Straight barrel, 54, 56 Support member, 68 Inlet channel switching valve, 70 Outlet channel switching valve, 72 Tank inlet pressure gauge, 74 Tank outlet pressure Total, 84 gas-liquid separation tank.

Claims (3)

A gas-liquid dissolution tank for dissolving gas into liquid under pressure,
Has a jet flow generating member causing jets to the tip, the inner intubation for introducing a mixture of gas and liquid inside the tank,
A draft tube open at both ends;
A baffle arranged in the outflow direction of the jet;
Equipped with a,
The draft tube is disposed so as to be submerged in the tank,
The inner intubation is inserted from one opening of the draft tube so that the tip of the jet generating member is located in the draft tube,
The baffle is gas-liquid mixing tank, wherein Rukoto are arranged to submerge outside than the other opening of the draft tube. The gas-liquid dissolution tank according to claim 1,
Gas-liquid mixing tank said jet the insertion tube is arranged to occur in a substantially vertically upward direction, characterized in Rukoto. The gas-liquid dissolution tank according to claim 1 or 2,
An exhaust pipe inserted at a predetermined length from the top of the tank to the inside;
A valve connected to the exhaust pipe for adjusting the exhaust amount;
A gas-liquid dissolution tank comprising:

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