Patent Application
20220323915
The present disclosure relates to an apparatus generating a liquid containing ultra-fine bubbles smaller than 1.0 μm in diameter, an ultra-fine bubble-containing liquid generating method, and an ultra-fine bubble-containing liquid.
Recently, there have been developed techniques for applying the features of fine bubbles such as microbubbles in micrometer-size in diameter and nanobubbles in nanometer-size in diameter. Especially, the utility of ultra-fine bubbles (hereinafter also referred to as “UFBs”) smaller than 1.0 μm in diameter has been confirmed in various fields.
Japanese Patent Laid-Open No. 2014-104441 describes an apparatus that generates fine bubbles by jetting a pressurized liquid in which a gas is pressurized and dissolved by a pressurized dissolution method from a nozzle.
Japanese Patent Laid-Open No. 2019-042732 discloses a technique of generating ultra-fine bubbles in a gas dissolving liquid by heating the gas dissolving liquid supplied from a gas dissolving unit (liquid supplying tank) with a heater provided in an ultra-fine bubble generating unit and generating film boiling.
The present disclosure is an ultra-fine bubble-containing liquid generating apparatus includes: a dissolving unit that generates a gas dissolving liquid in which a predetermined gas is dissolved into a liquid; an ultra-fine bubble generating unit that generates an ultra-fine bubble in the gas dissolving liquid; and a temperature controlling unit that controls at least one of temperatures of the dissolving unit and the ultra-fine bubble generating unit such that the temperature of the ultra-fine bubble generating unit is equal to or lower than the temperature of the dissolving unit.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
In the techniques disclosed in Japanese Patent Laid-Open Nos. 2014-104441 and 2019-042732, a gas is dissolved into a liquid before fine bubbles are generated. However, any of the patent literatures do not disclose a relationship between a temperature of a gas dissolving unit that dissolves a gas and a temperature of a bubble generating unit that generates fine bubbles. In general, in a case where the temperature is decreased, the gas dissolving amount into the liquid is increased. For this reason, in a case where a gas dissolving liquid in which a gas is dissolved to reach a saturation state by the gas dissolving unit is supplied to the bubble generating unit, if the temperature of the bubble generating unit is higher than the temperature of the gas dissolving unit, the gas dissolved in the gas dissolving liquid is precipitated again as air bubbles. Consequently, the dissolving amount of the gas in the gas dissolving liquid is reduced, and the amount of the bubbles generated by the bubble generating unit is accordingly reduced; thus, the efficiency of generating bubbles is reduced.
To deal with this, the present disclosure provides a technique that allows for efficient generation of ultra-fine bubbles.
First, a basic configuration of a UFB generating apparatus using a film boiling phenomenon is described.
When a certain amount of the liquid W is reserved in the degassing container 101 and then the depressurizing pump 103 is activated with all the valves closed, already-gasified gas components are discharged, and gasification and discharge of gas components dissolved in the liquid W are also prompted. In this process, the internal pressure of the degassing container 101 may be depressurized to around several hundreds to thousands of Pa (1.0 Torr to 10.0 Torr) while checking a manometer 108. The gases to be removed by the pre-processing unit 100 includes nitrogen, oxygen, argon, carbon dioxide, and so on, for example.
The above-described degassing processing can be repeatedly performed on the same liquid W by utilizing the liquid circulation passage 105. Specifically, the shower head 102 is operated with the valve 109 of the liquid introduction passage 104 and a valve 110 of the liquid discharge passage 106 closed and a valve 107 of the liquid circulation passage 105 opened. This allows the liquid W reserved in the degassing container 101 and degassed once to be resprayed in the degassing container 101 from the shower head 102. In addition, with the depressurizing pump 103 operated, the gasification processing by the shower head 102 and the degassing processing by the depressurizing pump 103 are repeatedly performed on the same liquid W. Every time the above processing utilizing the liquid circulation passage 105 is performed repeatedly, it is possible to decrease the gas components contained in the liquid W in stages. Once the liquid W degassed to a desired purity is obtained, the liquid W is transferred to the dissolving unit 200 through the liquid discharge passage 106 with the valve 110 opened.
With the above-described degassing processing performed as pre-processing, it is possible to increase the purity and the solubility of a desired gas with respect to the liquid W in the dissolving processing described later. Additionally, it is possible to increase the purity of desired UFBs contained in the liquid W in the T-UFB generating unit described later. That is, it is possible to efficiently generate a UFB-containing liquid (ultra-fine bubble-containing liquid) with high purity by providing the pre-processing unit 100 to precede the dissolving unit 200 and the T-UFB generating unit 300.
The liquid W supplied from the pre-processing unit 100 is supplied and reserved into the dissolving container 201 through the liquid introduction passage 204. Meanwhile, a gas G is supplied to the dissolving container 201 through the gas introduction passage 205.
Once predetermined amounts of the liquid W and the gas G are reserved in the dissolving container 201, the pressurizing pump 207 is activated to increase the internal pressure of the dissolving container 201 to about 0.5 MPa. A safety valve 208 is arranged between the pressurizing pump 207 and the dissolving container 201. With the rotation plate 202 in the liquid rotated via the rotation shaft 203, the gas G supplied to the dissolving container 201 is transformed into air bubbles, and the contact area between the gas G and the liquid W is increased to prompt the dissolution into the liquid W. This operation is continued until the solubility of the gas G reaches almost the maximum saturation solubility. In this case, a unit for decreasing the temperature of the liquid may be provided to dissolve the gas as much as possible. When the gas is with low solubility, it is also possible to increase the internal pressure of the dissolving container 201 to 0.5 MPa or higher. In this case, the material and the like of the container need to be the optimum for safety sake.
Once the liquid W in which the components of the gas G are dissolved at a desired concentration is obtained, the liquid W is discharged through the liquid discharge passage 206 and supplied to the T-UFB generating unit 300. In this process, a back-pressure valve 209 adjusts the flow pressure of the liquid W to prevent excessive increase of the pressure during the supplying.
The gas-dissolved liquid 3 in the drawings means “a region of the liquid W in which the dissolution concentration of the gas G mixed therein is relatively high.” In the gas components actually dissolved in the liquid W, the concentration of the gas components in the gas-dissolved liquid 3 is the highest at a portion surrounding the air bubble 2. In a case where the gas-dissolved liquid 3 is separated from the air bubble 2 the concentration of the gas components of the gas-dissolved liquid 3 is the highest at the center of the region, and the concentration is continuously decreased as away from the center. That is, although the region of the gas-dissolved liquid 3 is surrounded by a broken line in
An element substrate 12 provided with a heating element 10 is arranged on a bottom section of the chamber 301. With a predetermined voltage pulse applied to the heating element 10, a bubble 13 generated by the film boiling (hereinafter, also referred to as a film boiling bubble 13) is generated in a region in contact with the heating element 10. Then, an ultrafine bubble (UFB) 11 containing the gas G is generated caused by expansion and shrinkage of the film boiling bubble 13. As a result, a UFB-containing liquid W containing many UFBs 11 is discharged from the liquid discharge passage 303.
As illustrated in
A cavitation-resistant film 310 for protecting the protective layer 309 from chemical and physical impacts due to the heat evolved by the resistive layer 307 is formed on a portion and around the portion on the surface of the protective layer 309, the portion corresponding to a heat-acting portion 311 that eventually becomes the heating element 10. A region on the surface of the resistive layer 307 in which the wiring 308 is not formed is the heat-acting portion 311 in which the resistive layer 307 evolves heat. The heating portion of the resistive layer 307 on which the wiring 308 is not formed functions as the heating element (heater) 10. As described above, the layers in the element substrate 12 are sequentially formed on the surface of the silicon substrate 304 by a semiconductor production technique, and the heat-acting portion 311 is thus provided on the silicon substrate 304.
The configuration illustrated in the drawings is an example, and various other configurations are applicable. For example, a configuration in which the laminating order of the resistive layer 307 and the wiring 308 is opposite, and a configuration in which an electrode is connected to a lower surface of the resistive layer 307 (so-called a plug electrode configuration) are applicable. In other words, as described later, any configuration may be applied as long as the configuration allows the heat-acting portion 311 to heat the liquid for generating the film boiling in the liquid.
The P-MOS 320 includes a source region 325 and a drain region 326 formed by partial introduction of N-type or P-type impurities in a top layer of the N-type well region 322, a gate wiring 335, and so on. The gate wiring 335 is deposited on a part of a top surface of the N-type well region 322 excluding the source region 325 and the drain region 326, with a gate insulation film 328 of several hundreds of A in thickness interposed between the gate wiring 335 and the top surface of the N-type well region 322.
The N-MOS 321 includes the source region 325 and the drain region 326 formed by partial introduction of N-type or P-type impurities in a top layer of the P-type well region 323, the gate wiring 335, and so on. The gate wiring 335 is deposited on a part of a top surface of the P-type well region 323 excluding the source region 325 and the drain region 326, with the gate insulation film 328 of several hundreds of Å in thickness interposed between the gate wiring 335 and the top surface of the P-type well region 323. The gate wiring 335 is made of polysilicon of 3000 Å to 5000 Å in thickness deposited by the CVD method. A C-MOS logic is constructed with the P-MOS 320 and the N-MOS 321.
In the P-type well region 323, an N-MOS transistor 330 for driving an electrothermal conversion element (heating resistance element) is formed on a portion different from the portion including the N-MOS 321. The N-MOS transistor 330 includes a source region 332 and a drain region 331 partially provided in the top layer of the P-type well region 323 by the steps of introduction and diffusion of impurities, a gate wiring 333, and so on. The gate wiring 333 is deposited on a part of the top surface of the P-type well region 323 excluding the source region 332 and the drain region 331, with the gate insulation film 328 interposed between the gate wiring 333 and the top surface of the P-type well region 323.
In this example, the N-MOS transistor 330 is used as the transistor for driving the electrothermal conversion element. However, the transistor for driving is not limited to the N-MOS transistor 330, and any transistor may be used as long as the transistor has a capability of driving multiple electrothermal conversion elements individually and can implement the above-described fine configuration. Although the electrothermal conversion element and the transistor for driving the electrothermal conversion element are formed on the same substrate in this example, those may be formed on different substrates separately.
An oxide film separation region 324 is formed by field oxidation of 5000 Å to 10000 Å in thickness between the elements, such as between the P-MOS 320 and the N-MOS 321 and between the N-MOS 321 and the N-MOS transistor 330. The oxide film separation region 324 separates the elements. A portion of the oxide film separation region 324 corresponding to the heat-acting portion 311 functions as a heat-accumulating layer 334, which is the first layer on the silicon substrate 304.
An interlayer insulation film 336 including a PSG film, a BPSG film, or the like of about 7000 Å in thickness is formed by the CVD method on each surface of the elements such as the P-MOS 320, the N-MOS 321, and the N-MOS transistor 330. After the interlayer insulation film 336 is made flat by heat treatment, an Al electrode 337 as a first wiring layer is formed in a contact hole penetrating through the interlayer insulation film 336 and the gate insulation film 328. On surfaces of the interlayer insulation film 336 and the Al electrode 337, an interlayer insulation film 338 including an SiO2 film of 10000 Å to 15000 Å in thickness is formed by a plasma CVD method. On the surface of the interlayer insulation film 338, a resistive layer 307 including a TaSiN film of about 500 Å in thickness is formed by a co-sputter method on portions corresponding to the heat-acting portion 311 and the N-MOS transistor 330. The resistive layer 307 is electrically connected with the Al electrode 337 near the drain region 331 via a through-hole formed in the interlayer insulation film 338. On the surface of the resistive layer 307, the wiring 308 of Al as a second wiring layer for a wiring to each electrothermal conversion element is formed. The protective layer 309 on the surfaces of the wiring 308, the resistive layer 307, and the interlayer insulation film 338 includes an SiN film of 3000 Å in thickness formed by the plasma CVD method. The cavitation-resistant film 310 deposited on the surface of the protective layer 309 includes a thin film of about 2000 Å in thickness, which is at least one metal selected from the group consisting of Ta, Fe, Ni, Cr, Ge, Ru, Zr, Ir, and the like. Various materials other than the above-described TaSiN such as TaN0.8, CrSiN, TaAl, WSiN, and the like can be applied as long as the material can generate the film boiling in the liquid.
Before a voltage is applied to the heating element 10, the atmospheric pressure is substantially maintained in the chamber 301. Once a voltage is applied to the heating element 10, the film boiling is generated in the liquid in contact with the heating element 10, and a thus-generated air bubble (hereinafter, referred to as the film boiling bubble 13) is expanded by a high pressure acting from inside (timing 1). A bubbling pressure in this process is expected to be around 8 to 10 MPa, which is a value close to a saturation vapor pressure of water.
The time for applying a voltage (pulse width) is around 0.5 μsec to 10.0 μsec, and the film boiling bubble 13 is expanded by the inertia of the pressure obtained in timing 1 even after the voltage application. However, a negative pressure generated with the expansion is gradually increased inside the film boiling bubble 13, and the negative pressure acts in a direction to shrink the film boiling bubble 13. After a while, the volume of the film boiling bubble 13 becomes the maximum in timing 2 when the inertial force and the negative pressure are balanced, and thereafter the film boiling bubble 13 shrinks rapidly by the negative pressure.
In the disappearance of the film boiling bubble 13, the film boiling bubble 13 disappears not in the entire surface of the heating element 10 but in one or more extremely small regions. For this reason, on the heating element 10, further greater force than that in the bubbling in timing 1 is generated in the extremely small region in which the film boiling bubble 13 disappears (timing 3).
The generation, expansion, shrinkage, and disappearance of the film boiling bubble 13 as described above are repeated every time a voltage pulse is applied to the heating element 10, and new UFBs 11 are generated each time.
The states of generation of the UFBs 11 in each process of the generation, expansion, shrinkage, and disappearance of the film boiling bubble 13 are further described in detail with reference to
Thereafter, the surface temperature of the heating element 10 keeps increasing to around 600 to 800° C. during the pulse application, and the liquid around the film boiling bubble 13 is rapidly heated as well. In
The gas-dissolved liquid 3 within the not-yet-bubbling negative pressure region 15 exceeds the pressure dissolution limit and is vaporized to become an air bubble. The thus-vaporized air bubbles have diameters of about 100 nm and thereafter float independently in the liquid W without disappearing in a short time. In this embodiment, the air bubbles vaporized by the pressure action during the shrinkage of the film boiling bubble 13 are called the second UFBs 11B.
In this case, the gas-dissolved liquid 3 within the not-yet-bubbling negative pressure region 15 is resonated by the shock waves made by the disappearance of the film boiling bubble 13, and the gas-dissolved liquid 3 exceeds the pressure dissolution limit and the phase transition is made in timing when the low pressure surface 17B passes therethrough. Specifically, a number of air bubbles are vaporized in the not-yet-bubbling negative pressure region 15 simultaneously with the disappearance of the film boiling bubble 13. In this embodiment, the air bubbles generated by the shock waves made by the disappearance of the film boiling bubble 13 are called fourth UFBs 11D.
The fourth UFBs 11D generated by the shock waves made by the disappearance of the film boiling bubble 13 suddenly appear in an extremely short time (1 μS or less) in an extremely narrow thin film-shaped region. The diameter is sufficiently smaller than that of the first to third UFBs, and the gas-liquid interface energy is higher than that of the first to third UFBs. For this reason, it is considered that the fourth UFBs 11D have different characteristics from the first to third UFBs 11A to 11C and generate different effects.
Additionally, the fourth UFBs 11D are evenly generated in many parts of the region of the concentric sphere in which the shock waves are propagated, and the fourth UFBs 11D evenly exist in the chamber 301 from the generation thereof. Although many first to third UFBs already exist in the timing of the generation of the fourth UFBs 11D, the presence of the first to third UFBs does not affect the generation of the fourth UFBs 11D greatly. It is also considered that the first to third UFBs do not disappear due to the generation of the fourth UFBs 11D.
As described above, it is expected that the UFBs 11 are generated in the multiple stages from the generation to the disappearance of the film boiling bubble 13 by the heat generation of the heating element 10. Although the above example illustrates the stages to the disappearance of the film boiling bubble 13, the way of generating the UFBs is not limited thereto. For example, with the generated film boiling bubble 13 communicating with the atmospheric air before the bubble disappearance, the UFBs can be generated also if the film boiling bubble 13 does not reach the disappearance.
Next, remaining properties of the UFBs are described. The higher the temperature of the liquid, the lower the dissolution properties of the gas components, and the lower the temperature, the higher the dissolution properties of the gas components. In other words, the phase transition of the dissolved gas components is prompted and the generation of the UFBs becomes easier as the temperature of the liquid is higher. The temperature of the liquid and the solubility of the gas are in the inverse relationship, and the gas exceeding the saturation solubility is transformed into air bubbles and appeared in the liquid as the liquid temperature increases.
Therefore, when the temperature of the liquid rapidly increases from normal temperature, the dissolution properties are decreased without stopping, and the generation of the UFBs starts. The thermal dissolution properties are decreased as the temperature increases, and a number of the UFBs are generated.
Conversely, when the temperature of the liquid decreases from normal temperature, the dissolution properties of the gas are increased, and the generated UFBs are more likely to be liquefied. However, such temperature is sufficiently lower than normal temperature. Additionally, since the once generated UFBs have a high internal pressure and large gas-liquid interface energy even when the temperature of the liquid decreases, it is highly unlikely that there is exerted a sufficiently high pressure to break such a gas-liquid interface. In other words, the once generated UFBs do not disappear easily as long as the liquid is stored at normal temperature and normal pressure.
In this embodiment, the first UFBs 11A described with
On the other hand, in the relationship between the pressure and the dissolution properties of liquid, the higher the pressure of the liquid, the higher the dissolution properties of the gas, and the lower the pressure, the lower the dissolution properties. In other words, the phase transition to the gas of the gas-dissolved liquid dissolved in the liquid is prompted and the generation of the UFBs becomes easier as the pressure of the liquid is lower. Once the pressure of the liquid becomes lower than normal pressure, the dissolution properties are decreased instantly, and the generation of the UFBs starts. The pressure dissolution properties are decreased as the pressure decreases, and a number of the UFBs are generated.
Conversely, when the pressure of the liquid increases to be higher than normal temperature, the dissolution properties of the gas are increased, and the generated UFBs are more likely to be liquefied. However, such pressure is sufficiently higher than the atmospheric pressure. Additionally, since the once generated UFBs have a high internal pressure and large gas-liquid interface energy even when the pressure of the liquid increases, it is highly unlikely that there is exerted a sufficiently high pressure to break such a gas-liquid interface. In other words, the once generated UFBs do not disappear easily as long as the liquid is stored at normal temperature and normal pressure.
In this embodiment, the second UFBs 11B described with
Those first to fourth UFBs generated by different causes are described individually above; however, the above-described generation causes occur simultaneously with the event of the film boiling. Thus, at least two types of the first to the fourth UFBs may be generated at the same time, and these generation causes may cooperate to generate the UFBs. It should be noted that it is common for all the generation causes to be induced by the volume change of the film boiling bubble generated by the film boiling phenomenon. In this specification, the method of generating the UFBs by utilizing the film boiling caused by the rapid heating as described above is referred to as a thermal-ultrafine bubble (T-UFB) generating method. Additionally, the UFBs generated by the T-UFB generating method are referred to as T-UFBs, and the liquid containing the T-UFBs generated by the T-UFB generating method is referred to as a T-UFB-containing liquid.
Almost all the air bubbles generated by the T-UFB generating method are 1.0 or less, and milli-bubbles and microbubbles are unlikely to be generated. That is, the T-UFB generating method allows dominant and efficient generation of the UFBs. Additionally, the T-UFBs generated by the T-UFB generating method have larger gas-liquid interface energy than that of the UFBs generated by a conventional method, and the T-UFBs do not disappear easily as long as being stored at normal temperature and normal pressure. Moreover, even if new T-UFBs are generated by new film boiling, it is possible to prevent disappearance of the already generated T-UFBs due to the impact from the new generation. That is, it can be said that the number and the concentration of the T-UFBs contained in the T-UFB-containing liquid have the hysteresis properties depending on the number of times the film boiling is made in the T-UFB-containing liquid. In other words, it is possible to adjust the concentration of the T-UFBs contained in the T-UFB-containing liquid by controlling the number of the heating elements provided in the T-UFB generating unit 300 and the number of the voltage pulse application to the heating elements.
Reference to
The cation exchange resins 412 are synthetic resins in which a functional group (ion exchange group) is introduced in a high polymer matrix having a three-dimensional network, and the appearance of the synthetic resins are spherical particles of around 0.4 to 0.7 mm. A general high polymer matrix is the styrene-divinylbenzene copolymer, and the functional group may be that of methacrylic acid series and acrylic acid series, for example. However, the above material is an example. As long as the material can remove desired inorganic ions effectively, the above material can be changed to various materials. The UFB-containing liquid W absorbed in the cation exchange resins 412 to remove the inorganic ions is collected by the collecting pipe 414 and transferred to the next step through the liquid discharge passage 415.
The impurities removed by the filtration filter 422 include organic materials that may be mixed at a tube or each unit, such as organic compounds including silicon, siloxane, and epoxy, for example. A filter film usable for the filtration filter 422 includes a filter of a sub-μm-mesh (a filter of 1 μm or smaller in mesh diameter) that can remove bacteria, and a filter of a nm-mesh that can remove virus.
After a certain amount of the UFB-containing liquid W is reserved in the storage container 421, the vacuum pump 423 is stopped and the valve 424 is opened to transfer the T-UFB-containing liquid in the storage container 421 to the next step through the liquid discharge passage 426. Although the vacuum filtration method is employed as the method of removing the organic impurities herein, a gravity filtration method and a pressurized filtration can also be employed as the filtration method using a filter, for example.
First, a predetermined amount of the UFB-containing liquid W is reserved into the precipitation container 431 through the liquid introduction passage 432 with the valve 433 closed, and leaving it for a while. Meanwhile, the solid substances in the UFB-containing liquid W are precipitated onto the bottom of the precipitation container 431 by gravity. Among the bubbles in the UFB-containing liquid, relatively large bubbles such as microbubbles are raised to the liquid surface by the buoyancy and also removed from the UFB-containing liquid. After a lapse of sufficient time, the valve 433 is opened, and the UFB-containing liquid W from which the solid substances and large bubbles are removed is transferred to the collecting unit 501 through the liquid discharge passage 434.
Reference to
Here, an effect of putting back the generated T-UFB-containing liquid W to the dissolving unit 200 again is simply described in accordance with details of specific testing performed by the present disclosures. First, in the T-UFB generating unit 300, 10000 pieces of the heating elements 10 were arranged on the element substrate 12. Industrial pure water was used as the liquid W and was flowed in the chamber 301 of the T-UFB generating unit 300 at a flow rate of 1.0 liter/hour. I this state, a voltage pulse with a voltage of 24 V and a pulse width of 1.0 μs was applied at a driving frequency of 10 KHz to the individual heating elements.
In a case where the generated T-UFB-containing liquid W was collected by the collecting unit 500 without putting back to the dissolving unit 200, that is, in a case where the number of circulation was one time, 3.6 billion pieces per mL of the UFBs were confirmed in the T-UFB-containing liquid W collected by the collecting unit 501. On the other hand, in a case where the operation of putting back the T-UFB-containing liquid W to the dissolving unit 200 was performed nine times, that is, in a case where the number of circulation was ten times, 36 billion pieces per mL of the UFBs were confirmed in the T-UFB-containing liquid W collected by the collecting unit 500. That is, it was confirmed that the UFB-containing concentration is increased in the proportion of the number of circulation. The number density of the UFBs as described above was obtained by counting the UFBs smaller than 1.0 μm in diameter contained in the UFB-containing liquid W of a predetermined volume by using a measuring instrument (model number SALD-7500) manufactured by SHIMADZU CORPORATION.
The collecting unit 500 collects and stores the UFB-containing liquid W transferred from the post-processing unit 400. The T-UFB-containing liquid collected by the collecting unit 500 is a UFB-containing liquid with high purity from which various impurities are removed.
In the collecting unit 500, the UFB-containing liquid W may be classified by the size of the T-UFBs by performing some stages of filtration processing. Since it is expected that the temperature of the T-UFB-containing liquid W obtained by the T-UFB generating method is higher than normal temperature, the collecting unit 500 may be provided with a cooling unit. The cooling unit may be provided as a part of the post-processing unit 400.
The schematic description of the UFB generating apparatus 1 is given above; however, it is needless to say that the illustrated multiple units can be changed, and not all of them need to be prepared. Depending on the type of the liquid W and the gas G to be used and the intended use of the T-UFB-containing liquid to be generated, a part of the above-described units may be omitted, or another unit other than the above-described units may be added.
For example, when the gas to be contained by the UFBs is the atmospheric air, the degassing unit as the pre-processing unit 100 and the dissolving unit 200 can be omitted. On the other hand, when multiple kinds of gases are desired to be contained by the UFBs, another dissolving unit 200 may be added.
The functions of some units illustrated in
The removing units for removing the impurities as illustrated in
Particularly, in a case where an impurity removing unit using an ion-exchange resin illustrated in
Now, the liquid W usable for generating the T-UFB-containing liquid is described. The liquid W usable in this embodiment is, for example, pure water, ion exchange water, distilled water, bioactive water, magnetic active water, lotion, tap water, sea water, river water, clean and sewage water, lake water, underground water, rain water, and so on. A mixed liquid containing the above liquid and the like is also usable. A mixed solvent containing water and soluble organic solvent can be also used. The soluble organic solvent to be used by being mixed with water is not particularly limited; however, the followings can be a specific example thereof. An alkyl alcohol group of the carbon number of 1 to 4 including methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, and tert-butyl alcohol. An amide group including N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N,N-dimethylformamide, and N,N-dimethylacetamide. A keton group or a ketoalcohol group including acetone and diacetone alcohol. A cyclic ether group including tetrahydrofuran and dioxane. A glycol group including ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, and thiodiglycol. A group of lower alkyl ether of polyhydric alcohol including ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, and triethylene glycol monobutyl ether. A polyalkylene glycol group including polyethylene glycol and polypropylene glycol. A triol group including glycerin, 1,2,6-hexanetriol, and trimethylolpropane. These soluble organic solvents can be used individually, or two or more of them can be used together.
A gas component that can be introduced into the dissolving unit 200 is, for example, hydrogen, helium, oxygen, nitrogen, methane, fluorine, neon, carbon dioxide, ozone, argon, chlorine, ethane, propane, air, and so on. The gas component may be a mixed gas containing some of the above. Additionally, it is not necessary for the dissolving unit 200 to dissolve a substance in a gas state, and the dissolving unit 200 may fuse a liquid or a solid containing desired components into the liquid W. The dissolution in this case may be spontaneous dissolution, dissolution caused by pressure application, or dissolution caused by hydration, ionization, and chemical reaction due to electrolytic dissociation.
Here, as a specific example, a case of using ozone gas as the gas component is described. First, a method of generating ozone gas may include an electric discharge method, an electrolytic method, and an ultraviolet lamp method. The above methods are described below in sequence.
The electric discharge method includes a silent electric discharge method and a surface electric discharge method. In the silent electric discharge method, an alternating-current high voltage is applied while an oxygen-containing gas is flowed between a pair of electrodes arranged in the form of parallel flat plates or coaxial cylinders. With this, discharge occurs in the oxygen-containing gas, and ozone gas is generated. One of or both the surfaces of the pair of electrodes need to be covered with a dielectric such as glass. The discharge occurs in a gas (air or oxygen) in association with charges on the surface of the dielectric alternately varied positively and negatively.
On the other hand, in the surface electric discharge method, a surface of a flat plate-shaped electrode is covered with a dielectric such as ceramics, and a linear electrode is arranged on the surface of the dielectric. Then, an alternating-current high voltage is applied between the flat plate-shaped electrode and the linear electrode. With this, discharge occurs on the surface of the dielectric, and ozone gas is generated.
A pair of electrodes with an electrolyte membrane arranged therebetween are arranged in water, and a direct-current voltage is applied between the two electrodes. With this, electrolysis of the water occurs, and ozone gas is generated with oxygen on the oxygen generation side. An ozone generator being practically used includes porous titanium having a platinum catalyst layer on a cathode, porous titanium having a lead dioxide catalyst layer on an anode, one using a perfluorosulfonic acid cation exchange membrane as an electrolyte membrane, and the like. According to the present apparatus, highly concentrated ozone of 20% by weight or greater can be generated.
Ozone gas is generated by exposing ultraviolet to the air and the like by using a similar principle as that of how the ozone layer of Earth is created. Usually, a mercury lamp is used as an ultraviolet lamp.
In a case of using ozone gas as the gas component, an ozone gas generating unit employing the methods (1) to (3) described above may be additionally added to the UFB generating apparatus 1 in
Next, a method of dissolving the generated ozone gas is described. A method appropriate for dissolving ozone gas into the liquid W may include an “air bubble dissolution method”, a “membrane contactor dissolution method”, and a “filled-layer dissolution method” in addition to the pressurized dissolution method illustrated in
This is a method of mixing ozone gas into the liquid W as bubbles and flowing the ozone gas with the liquid W to dissolve. For example, there are a bubbling method in which ozone gas is blown from a lower portion of a container retaining the liquid W, an ejector method in which a narrow portion is provided in a part of a pipe through which the liquid W flows and ozone gas is blown into the narrow portion, a method of agitating the liquid W and the ozone gas by a pump, and the like. The air bubble dissolution method is a comparatively compact dissolution method and is used in a water treatment plant and the like.
This is a method of absorbing and dissolving ozone gas into the liquid W by flowing the liquid W through a porous Teflon (registered trademark) membrane while the ozone gas is flowed through the outside.
(iii) Filled-Layer Dissolution Method
This is a method of dissolving ozone gas into the liquid W in a filled-layer by making counterflow of the ozone gas and the liquid by flowing the liquid W from the top of the filled-layer while flowing the ozone gas from the bottom.
In a case of employing the methods (i) to (iii) described above, the dissolving unit 200 of the UFB generating apparatus 1 may be changed from the one with the configuration illustrated in
Particularly, in terms of the severe toxicity, ozone gas with high purity is obligated to purchase with a gas cylinder and the usage is limited unless a special environment is prepared. For this reason, it is difficult to generate ozone microbubbles and ozone ultra-fine bubbles by conventional methods of generating microbubbles or ultra-fine bubbles by gas introduction (for example, a Venturi method, a swirl flow method, a pressurized dissolution method, and so on).
On the other hand, as a method of generating ozone dissolving water, a method of generating ozone from oxygen supplied by the above-described electric discharge method, electrolytic method, or ultraviolet lamp method and dissolving into the water concurrently with the ozone generation is useful from the points of the safety and the handleability.
However, in a case of employing a cavitation method and the like, although it is possible to generate ozone ultra-fine bubbles by using the ozone dissolving water, there are still problems such as an increase in size of the apparatus and the difficulty in increasing the concentration of the ozone ultra-fine bubbles.
In contrast, the T-UFB generating method of the present embodiment is better than the other generating methods such as the cavitation method in that the apparatus can be proportionally small in size, and highly concentrated ozone ultra-fine bubbles can be generated from the ozone dissolving water.
Next, the characteristics and the effects of the above-described T-UFB generating method are described by comparing with a conventional UFB generating method. For example, in a conventional air bubble generating apparatus as represented by the Venturi method, a mechanical depressurizing structure such as a depressurizing nozzle is provided in a part of a flow passage. A liquid flows at a predetermined pressure to pass through the depressurizing structure, and air bubbles of various sizes are generated in a downstream region of the depressurizing structure.
In this case, among the generated air bubbles, since the relatively large bubbles such as milli-bubbles and microbubbles are affected by the buoyancy, such bubbles rise to the liquid surface and disappear. Even the UFBs that are not affected by the buoyancy may also disappear with the milli-bubbles and microbubbles since the gas-liquid interface energy of the UFBs is not very large. Additionally, even if the above-described depressurizing structures are arranged in series, and the same liquid flows through the depressurizing structures repeatedly, it is impossible to store for a long time the UFBs of the number corresponding to the number of repetitions. In other words, it has been difficult for the UFB-containing liquid generated by the conventional UFB generating method to maintain the concentration of the contained UFBs at a predetermined value for a long time.
In contrast, in the T-UFB generating method of this embodiment utilizing the film boiling, a rapid temperature change from normal temperature to about 300° C. and a rapid pressure change from normal pressure to around a several megapascal occur locally in a part extremely close to the heating element. The heating element is a rectangular shape having one side of around several tens to hundreds of μm. It is around 1/10 to 1/1000 of the size of a conventional UFB generating unit. Additionally, with the gas-dissolved liquid within the extremely thin film region of the film boiling bubble surface exceeding the thermal dissolution limit or the pressure dissolution limit instantaneously (in an extremely short time under microseconds), the phase transition occurs and the gas-dissolved liquid is precipitated as the UFBs. In this case, the relatively large bubbles such as milli-bubbles and microbubbles are hardly generated, and the liquid contains the UFBs of about 100 nm in diameter with extremely high purity. Moreover, since the T-UFBs generated in this way have sufficiently large gas-liquid interface energy, the T-UFBs are not broken easily under the normal environment and can be stored for a long time.
Particularly, the present invention using the film boiling phenomenon that enables local formation of a gas interface in the liquid can form an interface in a part of the liquid close to the heating element without affecting the entire liquid region, and a region on which the thermal and pressure actions performed can be extremely local. As a result, it is possible to stably generate desired UFBs. With further more conditions for generating the UFBs applied to the generation liquid through the liquid circulation, it is possible to additionally generate new UFBs with small effects on the already-made UFBs. As a result, it is possible to produce a UFB liquid of a desired size and concentration relatively easily.
Moreover, since the T-UFB generating method has the above-described hysteresis properties, it is possible to increase the concentration to a desired concentration while keeping the high purity. In other words, according to the T-UFB generating method, it is possible to efficiently generate a long-time storable UFB-containing liquid with high purity and high concentration.
The method of dissolving ozone gas into the liquid W is described herein; however, a method of dissolving nitric oxide gas into the liquid W instead of ozone gas may be applied. Use of nitric oxide gas is also appropriate for medical and clinical application by using a biological activity function and the like.
Next, characteristic configurations and operations of the present disclosure are described based on first to fourth embodiments described below.
A liquid introduction flow passage 1102 that introduces the liquid to the gas dissolving tank 1101 and a gas introduction flow passage 1103 that introduces the gas to the gas dissolving tank 1101 are coupled to the gas dissolving tank 1101. The gas dissolving tank 1101 generates a gas dissolving liquid 1104 by dissolving the gas introduced from the gas introduction flow passage 1103 into the liquid introduced from the liquid introduction flow passage 1102.
The gas dissolving liquid 1104 generated in the gas dissolving tank 1101 is transferred to the UFB generating unit 1107 by a pump 1105 through the inside of a gas dissolving liquid flow passage 1106A. The UFB generating unit 1107 generates the UFBs from the dissolved gas contained in the gas dissolving liquid. In this process, the amount of the generated UFBs is large as the amount of the dissolved gas contained in the gas dissolving liquid 1104 is large. With this taken into consideration, in order to set a low temperature state in which the solubility of the gas into the liquid is increased, a temperature controlling unit 2110 for gas dissolving tank (hereinafter, also referred to as a first temperature controlling unit) is disposed in the gas dissolving tank 1101. The first temperature controlling unit 2110 includes a coolant flow passage 2111 routed in an outer periphery of the gas dissolving tank 1101 and a coolant supplying unit 2112 that circulates a coolant such as an antifreeze liquid in the coolant flow passage 2111. The gas dissolving tank 1101 can be cooled by circulating the coolant in the coolant flow passage 2111. As the gas dissolving tank 1101 is cooled and thus the liquid introduced therein is cooled, the amount of the gas dissolved into the liquid is increased.
The first temperature controlling unit 2110 is not limited to have the above-described configuration using the coolant flow passage, and other configurations may be applied as long as it is a configuration capable of adjusting the temperature of the liquid in the gas dissolving tank 1101. Additionally, as long as the configuration of the gas dissolving tank 1101 is capable of dissolving the gas into the liquid, the shape, structure, and the like are not particularly limited.
In the UFB generating unit 1107, a temperature controlling unit 2120 for UFB generating unit (hereinafter, also referred to as a second temperature controlling unit) is disposed to control the temperature of the liquid to be equal to or lower than a temperature in the gas dissolving tank 1101. This is for inhibiting the gas dissolved by the gas dissolving tank 1101 from exceeding the saturation solubility of the gas and becoming air bubbles to precipitate in a case where the temperature of the UFB generating unit 1107 is higher than that of the gas dissolving tank 1101. The second temperature controlling unit 2120 may have a similar configuration as that of the first temperature controlling unit 2110. That is, the second temperature controlling unit 2120 can include a coolant flow passage 2121 routed in an outer periphery of the UFB generating unit 1107 and a coolant supplying unit 2122 that circulates a coolant in the coolant flow passage 2121. Note that, also the second temperature controlling unit 2120 may have other configurations as long as it is a configuration capable of controlling the temperature of the liquid in the UFB generating unit 1107.
In the present embodiment, the gas dissolving liquid flow passage 1106A that allows the gas dissolving tank 1101 and the UFB generating unit 1107 to communicate with each other is short, and it hardly affects substantially the temperature rise of the gas dissolving liquid 1104. For this reason, no temperature controlling unit is disposed in the gas dissolving liquid flow passage 1106A. The UFB-containing liquid generated in the UFB generating unit 1107 is injected into a container 1111 through an outlet port flow passage 1110. Since the outlet port flow passage 1110 and the container 1111 are a route through which the liquid passes after the UFBs are generated, the temperature controlling unit is not required to be disposed therein.
<Liquid and Gas Introduced into Gas Dissolving Tank>
As the liquid introduced into the gas dissolving tank 1101, for example, pure water, ion exchange water, distilled water, physiologically active water, magnetically active water, lotion, tap water, sea water, river water, clean water and sewage water, lake water, underground water, rainwater, and so on are usable. A mixed liquid including the above liquids and the like is also usable. A mixed solvent of water and a water-soluble organic solvent is also usable.
Although the water-soluble organic solvent to be mixed with water for use is not particularly limited, the followings can be a specific example thereof
The above-described water-soluble organic solvent may be used independently or two or more types may be used in combination.
As the gas, for example, hydrogen, helium, oxygen, nitrogen, methane, fluorine, neon, carbon dioxide, ozone, argon, chlorine, ethane, propane, air, a mixed gas containing the above, and the like are usable.
In the first nozzle portion 1210, an introduction portion 1211, a first tapered portion 1212, and a first throat portion 1213 are continuously formed sequentially from the upstream side toward the downstream side of a nozzle flow passage 1202. In the second nozzle portion 1220, a first enlarged portion 1221, a second tapered portion 1222, and a second throat portion 1223 are provided. In the third nozzle portion 1230, a second enlarged portion 1231, a third tapered portion 1232, and a third throat portion 1233 are formed.
An inner surface of the introduction portion 1211 is a substantially cylindrical surface with a central axis J1 of the nozzle flow passage 1202 as the center, and the flow passage area of the introduction portion 1211 is substantially constant in a direction along the central axis J1. An upstream end of the first tapered portion 1212 communicates with a downstream end of the introduction portion 1211. A flow passage cross section at the upstream end of the first tapered portion 1212 coincides with a flow passage cross section at the downstream end of the introduction portion 1211. An inner surface of the first tapered portion 1212 has a substantially truncated cone shape with the central axis J1 as the center. The flow passage area of the first tapered portion 1212 is gradually reduced from the upstream toward the downstream of the nozzle flow passage 1202 (that is, toward a direction in which the gas dissolving liquid 1104 flows). In a vertical cross section including the central axis J1, an angle α1 formed by the inner surface of the first tapered portion 1212 and the central axis J1 is preferably 10° or greater and 90° or smaller.
An upstream end of the first throat portion 1213 is connected to a downstream end of the first tapered portion 1212. A flow passage cross section at the upstream end of the first throat portion 1213 coincides with a flow passage cross section at the downstream end of the first tapered portion 1212. An inner surface of the first throat portion 1213 is a substantially cylindrical surface with the central axis J1 as the center, and the flow passage area of the first throat portion 1213 is substantially constant in the central axis J1 direction. The flow passage area of the first throat portion 1213 is the smallest in the first nozzle portion 1210. The length of the first throat portion 1213 in the central axis J1 direction is preferably 1.1 times or more and 10 times or less of the diameter of the flow passage cross section of the first throat portion 1213 and is more preferably 1.5 times or more and 2 times or less thereof. In the following descriptions, the length of a flow passage in the central axis J1 direction is simply referred to as a “length”, and the diameter of a flow passage cross section is simply referred to as a “diameter”.
An opening at a downstream end of the first throat portion 1213 is a first jetting port 1217 that jets a fluid flowing from the first tapered portion 1212 into the first throat portion 1213 as a jet flow to the first enlarged portion 1221 of the second nozzle portion 1220 adjacent to the first jetting port 1217 on the downstream side. If a part of the flow passage area of the first nozzle portion 1210 is slightly changed, a portion having the smallest flow passage area affects the entire liquid fluidity of the first throat portion 1213.
The first enlarged portion 1221 is connected to the first jetting port 1217 of the first throat portion 1213, and the flow passage area is immediately enlarged from the first throat portion 1213. In a vertical cross section including the central axis J1, an angle (31 formed by a first surface 1221a of the first enlarged portion 1221 and the central axis J1 is preferably 45° or greater and 90° or smaller. In the present embodiment, the angle (31 formed by the first surface 1221a of the first enlarged portion 1221 and the central axis J1 is 90°. A flow passage cross section at an upstream end of the first enlarged portion 1221 is greater than the first jetting port 1217 of the first throat portion 1213, and a periphery of the flow passage cross section (opening portion at the upstream end of the first enlarged portion 1221) is positioned around the first jetting port 1217 to be away radially outward from the first jetting port 1217.
The second tapered portion 1222 is connected to a downstream end of the first enlarged portion 1221. A flow passage cross section at an upstream end of the second tapered portion 1222 coincides with a flow passage cross section of the downstream end of the first enlarged portion 1221. An inner surface of the second tapered portion 1222 has a substantially truncated cone shape with the central axis J1 as the center. The flow passage area of the second tapered portion 1222 is gradually reduced from the upstream toward the downstream. In a cross section including the central axis J1, an angle α2 formed by the inner surface of the second tapered portion 1222 is preferably 10° or greater and 90° or smaller.
The second throat portion 1223 communicates with a downstream end of the second tapered portion 1222. A flow passage cross section at an upstream end of the second throat portion 1223 coincides with a flow passage cross section at the downstream end of the second tapered portion 1222. An inner surface of the second throat portion 1223 is a substantially cylindrical surface with the central axis J1 as the center, and the flow passage area of the second throat portion 1223 is substantially constant. The flow passage area of the second throat portion 1223 is the smallest in the second nozzle portion 1220. The length of the second throat portion 1223 is preferably 1.1 times or more and 10 times or less of the diameter of the second throat portion 1223 and is more preferably 1.5 times or more and 2 times or less thereof.
An opening at a downstream end of the second throat portion 1223 is a second jetting port 1227 that jets a fluid flowing from the second tapered portion 1222 toward the second throat portion 1223 as a jet flow to the second enlarged portion 1231 of the third nozzle portion 1230 adjacent to the second jetting port 1227 on the downstream side. If a part of the flow passage area of the second nozzle portion 1220 is slightly changed, a portion having the smallest flow passage area affects the entire liquid fluidity of the second throat portion 1223.
The second enlarged portion 1231 is connected to the second jetting port 1227 of the second throat portion 1223, and the flow passage area is immediately enlarged from the second throat portion 1223. In a vertical cross section including the central axis J1, an angle β2 formed by a first surface 1231a of the second enlarged portion 1231 and the central axis J1 is preferably 45° or greater and 90° or smaller. In the present embodiment, the angle β2 formed by the first surface 1231a of the second enlarged portion 1231 and the central axis J1 is 90°. A flow passage cross section at an upstream end of the second enlarged portion 1231 is greater than the second jetting port 1227 of the second throat portion 1223, and an outer peripheral edge of the flow passage cross section (opening portion at the upstream end of the second enlarged portion 1231) is positioned around the second jetting port 1227 to be away radially outward from the second jetting port 1227.
An upstream end of the third tapered portion 1232 is connected to a downstream end of the second enlarged portion 1231. A flow passage cross section at the upstream end of the third tapered portion 1232 coincides with a flow passage cross section at the downstream end of the second enlarged portion 1231. An inner surface of the third tapered portion 1232 has a substantially truncated cone shape with the central axis J1 as the center. The flow passage area of the third tapered portion 1232 is gradually reduced from the upstream toward the downstream. In a vertical cross section including the central axis J1, an angle α3 formed by the inner surface of the third tapered portion 1232 is preferably 10° or greater and 90° or smaller.
An upstream end of the third throat portion 1233 is connected to a downstream end of the third tapered portion 1232. A flow passage cross section at the upstream end of the third throat portion 1233 coincides with a flow passage cross section at the downstream end of the third tapered portion 1232. An inner surface of the third throat portion 1233 is a substantially cylindrical surface with the central axis J1 as the center, and a flow passage area of the third throat portion 1233 is substantially constant. The flow passage area of the third throat portion 1233 is the smallest in the third nozzle portion 1230. The length of the third throat portion 1233 is preferably 1.1 times or more and 10 times or less of the diameter of the third throat portion 1233 and is more preferably 1.5 times or more and 2 times or less thereof.
An opening at a downstream end of the third throat portion 1233 is a third jetting port 1237 that jets a fluid flowing from the third tapered portion 1232 into the third throat portion 1233 as a jet flow to the downstream side. If a part of the flow passage area of the third nozzle portion 1230 is slightly changed, a portion having the smallest flow passage area affects the entire liquid fluidity of the third throat portion 1233. Preferably, the diameter of the third throat portion 1233 is equal to or greater than the diameter of the second throat portion 1223, and the diameter of the second throat portion 1223 is equal to or greater than the diameter of the first throat portion 1213.
In the present embodiment, the first tapered portion 1212, the second tapered portion 1222, and the third tapered portion 1232 have the same shape. The first enlarged portion 1221 and the second enlarged portion 1231 have the same shape. The diameters of the introduction portion 1211, the first enlarged portion 1221, and the second enlarged portion 1231 are about 4 to 5 times as great as the diameter of the first throat portion 1213, the diameter of the second throat portion 1223, and the diameter of the third throat portion 1233, respectively. Each diameter of the first throat portion 1213, the second throat portion 1223, and the third throat portion 1233 is desirably increased from the upstream toward the downstream, and more desirably, the increase rate of the increase in the diameter is desirably at 7% or less. In this case, the increase rate indicates a ratio expressed by the following expression.
Increase rate=(diameter of downstream throat portion−diameter of upstream throat portion)/diameter of downstream throat portion×100(%)
In the above expression, for example, if the upstream throat portion is the first throat portion 1213, the downstream throat portion is the second throat portion 1223, and if the upstream throat portion is second throat portion 1223, the downstream throat portion is the third throat portion 1233.
In the UFB generating unit 1107 having the above-described configuration, the gas dissolving liquid 1104 flowing into the nozzle flow passage 1202 from a nozzle inlet port 1201 flows into the first throat portion 1213 while gradually accelerating in the first tapered portion 1212. The flow velocity of the gas dissolving liquid 1104 in the first throat portion 1213 is preferably 7 to 30 m per second. In the first throat portion 1213, the static pressure of the gas dissolving liquid 1104 is reduced. Accordingly, the gas (dissolved gas) dissolved in the gas dissolving liquid 1104 exceeds the saturation solubility of the gas and precipitates into the liquid as fine air bubbles. The liquid containing the fine air bubbles (fine air bubble-containing liquid) is jetted as a jet flow from the first jetting port 1217 toward the first enlarged portion 1221.
The precipitation of the fine air bubbles continues also in the fine air bubble-containing liquid jetted to the first enlarged portion 1221. The fine air bubbles are made finer by shear force and the like generated in the first enlarged portion 1221 by the jet flow from the first jetting port 1217. The fine air bubble-containing liquid flowing through the first enlarged portion 1221 flows into the second throat portion 1223 while gradually accelerating in the second tapered portion 1222 and is jetted as a jet flow from the second jetting port 1227 toward the second enlarged portion 1231. The fine air bubbles contained in the fine air bubble-containing liquid jetted to the second enlarged portion 1231 is made finer by shear force and the like generated in the second enlarged portion 1231 by the jet flow.
The fine air bubble-containing liquid flowing through the second enlarged portion 1231 flows into the third throat portion 1233 while gradually accelerating in the third tapered portion 1232 and is jetted as a jet flow from the third jetting port 1237 toward the outlet port flow passage 1110. The fine air bubbles in the fine air bubble-containing liquid are made finer by shear force and the like generated in the third enlarged portion 1234 by the jet flow, and thus a UFB-containing liquid containing many UFBs smaller than 1 μm in diameter is generated.
In the above-described UFB generating apparatus, the first temperature controlling unit 2110 and the second temperature controlling unit 2120 need to control the gas dissolving tank 1101 and the UFB generating unit 1107 within a higher temperature range than the coagulation point of the gas dissolving liquid in order to avoid the coagulation (freezing) of the gas dissolving liquid. The temperature range as the control target is preferably a range from the coagulation point of the gas dissolving liquid to a temperature higher than the coagulation point 15° C. or more, and more preferably, the temperature range is a range to a temperature higher than the coagulation point of the gas dissolving liquid 10° C. or more. The temperature of the UFB generating unit 1107 is preferably controlled to be lower than the temperature of the gas dissolving tank 1101 2° C. or more, and more preferably, the temperature of the UFB generating unit 1107 is controlled to be lower than the temperature of the gas dissolving tank 1101 5° C. or more.
In the present embodiment, in the UFB generating apparatus, the temperature of the gas dissolving tank 1101 was set to 10° C. by the first temperature controlling unit 2110, and the temperature of the UFB generating unit 1107 was set to 5° C. by the second temperature controlling unit 2120. Under the temperature conditions, the UFBs were generated, and the UFB concentration was measured. The temperature of the gas dissolving tank 1101 in the present embodiment was measured by disposing a sensor in the liquid in the gas dissolving tank 1101. The temperature of the UFB generating unit 1107 was measured by disposing a sensor on the upstream side of the gas dissolving liquid flow passage 1106A.
The liquid used was pure water, and oxygen was used as the gas dissolved in the pure water. The amount of the pure water introduced into the gas dissolving tank 1101 was 10 L. In the gas dissolving tank 1101, oxygen was introduced at a flow rate of about 100 mL/min, bubbling was performed in the gas dissolving tank 1101 for an hour to dissolve oxygen into the pure water and make a gas dissolving liquid, and thus an oxygen dissolving water was generated.
After the bubbling for an hour, the amount of the dissolved oxygen in the oxygen dissolving water was measured by a dissolved oxygen analyzer. As a result, the amount of the dissolved oxygen in the oxygen dissolving water was 54 mg/L. In contrast, the measured value of the amount of the dissolved oxygen contained in the pure water at the normal temperature before the oxygen dissolution was 8 mg/L. Accordingly, it was found that sufficient oxygen was dissolved in the oxygen dissolving water generated by the oxygen dissolving processing in the gas dissolving tank 1101 in the present embodiment.
Next, the oxygen dissolving water as the gas dissolving liquid was introduced into the UFB generating unit 1107 at a flow rate of about 1 L/min, and the UFB-containing liquid was generated in the oxygen dissolving water passing through the UFB generating unit 1107. As described above, since the UFB generating unit 1107 was set to be 5° C. lower than the set temperature of the gas dissolving tank 1101, oxygen dissolved in the gas dissolving tank 1101 did not reach the saturation state in the UFB generating unit 1107, and almost all the oxygen was used for the UFB generating. Thereafter, the UFB-containing liquid generated by the UFB generating unit 1107 passed through the discharge route 10 and was stored in the container 1111.
The concentration of the generated UFB-containing liquid stored in the container 1111 was measured by using SALD7500nano (manufactured by SHIMADZU CORPORATION). As a result, in the UFB-containing liquid generated, it was confirmed that the concentration of the UFBs of 1 μm or smaller was about 100 hundred million pieces/mL, and the average particle diameter of the UFBs was 110 nm.
The UFB generating unit 1113 in the UFB-containing liquid generating apparatus 1002 in the present embodiment employs the T-UFB generating method described in the above-described basic configuration. In the UFB generating unit 1113, the temperature controlling unit (second temperature controlling unit) 2220 for UFB generating unit is provided. The UFB generating unit 1113 and the second temperature controlling unit 2220 are described later.
In the present embodiment, the temperature controlling unit 2230 for gas dissolving liquid flow passage that controls the temperature of the gas dissolving liquid flow passage 1106B transferring the gas dissolving liquid generated in the gas dissolving tank 1101 to the UFB generating unit 1113 is provided. Configurations of units in the UFB-containing liquid generating apparatus 1002 in the second embodiment are described below in more detail while focusing on the different points from the first embodiment.
In the UFB generating unit 1113 having the above-described configuration, the gas dissolving liquid 1104 generated in the gas dissolving tank 1101 is introduced from the inlet 1401 to the UFB generating flow passage 1404 by way of the gas dissolving liquid flow passage 1106B. The gas dissolving liquid 1104 introduced in the UFB generating flow passage 1404 is heated by the heating elements 1402 while passing through the element substrate 1403, and film boiling occurs. Consequently, UFBs 1405 are generated in the gas dissolving liquid 1104, and the UFB-containing liquid is generated. The UFB-containing liquid generated in the UFB generating flow passage 1404 is transferred to the outlet port flow passage 1110 from the outlet 1406 and stored in the container 1111.
Referring back to
The UFB-containing liquid generating apparatus of the present embodiment having the above-described configuration was used to generate the UFBs under the conditions described below and measure the UFB concentration. The temperature of the gas dissolving tank 1101 was measured by disposing a sensor in the liquid in the gas dissolving tank 1101. The temperature of the UFB generating unit 1113 was measured by disposing a sensor on an upstream side of the inlet 1401 of the UFB generating flow passage 1404.
The liquid used was pure water, and oxygen was used as the gas dissolved in the pure water. The amount of the pure water introduced into the gas dissolving tank 1101 was 10 L, and the temperature of the gas dissolving tank 1101 was set at 10° C. Oxygen was introduced into the gas dissolving tank 1101 at a flow rate of about 100 mL/min, bubbling was performed in the gas dissolving tank 1101 for an hour to dissolve oxygen into the pure water. As a result of measuring by a dissolved oxygen analyzer, the amount of the dissolved oxygen in the generated oxygen dissolving water was 54 mg/L.
Next, the oxygen dissolving water was introduced into the UFB generating unit 1113 at a flow rate of about 1 L/min, and the UFB-containing liquid was generated. In this process, the number of the heating elements 1402 in the UFB generating unit 1113 was 100,000 pieces, the driving frequency of the heating elements 1402 was 20 kHz, the pulse width of the pulse signal applied to the driving heating elements was 1.0 μsec, the pulse voltage was 24V, and the temperature of the UFB generating unit 1113 was 5° C. The generated UFB-containing liquid passed through the outlet port flow passage 1110 and was stored in the container 1111.
The UFB concentration in the UFB-containing liquid generated was measured by SALD7500nano (manufactured by SHIMADZU CORPORATION). As a result, it was confirmed that the concentration of the UFBs of 1 μm or smaller contained in the UFB-containing liquid was about 1.4 billion pieces/mL, and the average particle diameter was 110 nm.
In the UFB-containing liquid generating apparatus of the present embodiment, the UFBs were generated while setting the temperature of the gas dissolving tank 1101 at 5° C. and the temperature of the UFB generating unit 1113 at 3° C. The conditions other than the temperatures were all the same as that of <Example (2) of Generating UFB-Containing Liquid> described above.
The UFB concentration in the UFB-containing liquid generated was measured by SALD7500nano (manufactured by SHIMADZU CORPORATION). As a result, it was confirmed that the concentration of the UFBs of 1 μm or smaller contained in the UFB-containing liquid was about 1.6 billion pieces/mL, and the average particle diameter was 110 nm.
In the circulation flow passage 1114, a temperature controlling unit 2340 for circulation flow passage is provided. The fourth temperature controlling unit 2340 includes a coolant flow passage 2341 arranged around the circulation flow passage 1114 and a coolant supplying unit 2342 that circulates a coolant in the coolant flow passage 2341. The temperature controlling unit 2340 makes it possible to suppress the temperature rise in the circulation flow passage 1114 of the UFB-containing liquid generated in the UFB generating unit 1113.
The UFB-containing liquid generating apparatus 1003 of the present embodiment having the above-described configuration was used to generate the UFB-containing liquid by continuing operation of the apparatus until the liquid in the gas dissolving tank 1101 was circulated five times, and thereafter, the UFB-containing liquid was stored into the container 1111 by way of the outlet port flow passage 1110. The temperature conditions to generate the UFB-containing liquid were the same as that of <Example (2) of Generating UFB-Containing Liquid> in the above-described second embodiment.
The concentration of the generated UFBs in the UFB-containing liquid generated was measured by SALD7500nano (manufactured by SHIMADZU CORPORATION). As a result, it was confirmed that the concentration of the UFBs of 1 μm or smaller contained in the UFB-containing liquid was about 4 billion pieces/mL, and the average particle diameter was 110 nm.
Thus, since the gas dissolving tank 1101 and the UFB generating unit 1113 exist in the same region in the storing chamber 1135, the temperatures of the gas dissolving tank 1101 and the UFB generating unit 1113 are the same. In the present embodiment, the second temperature controlling unit 2220 and the third temperature controlling unit 2230 described in the second embodiment are not provided.
The UFB-containing liquid generating apparatus 1004 having the above-described configuration was used to generate the UFB-containing liquid while setting the conditions other than the temperature conditions the same as that of the second embodiment. The temperatures of the gas dissolving tank 1101 and the UFB generating unit 1113 during the UFB generating were set at 5° C. by the temperature controlling unit in the storing chamber 1135.
The UFB concentration in the UFB-containing liquid generated was measured by SALD7500nano (manufactured by SHIMADZU CORPORATION). As a result, it was confirmed that the concentration of the UFBs of 1 μm or smaller contained in the UFB-containing liquid was about 1.2 billion pieces/mL, and the average particle diameter was 110 nm.
As described above, sufficient UFB generating concentration and average particle diameter can be obtained also in the present embodiment. However, the UFB concentration of the UFB-containing liquid generated in the present embodiment is lower than the UFB concentration of the UFB-containing liquid generated in <Example (2) of Generating UFB-Containing Liquid> in the second embodiment. It can be considered that this is because of the following reasons.
In the present embodiment, since the gas dissolving tank 1101 and the UFB generating unit 1113 are controlled at the same spatial temperature, a slight temperature rise occurs in the UFB generating unit 1113 by an effect of the heating elements 1402 and the like. In this case, the dissolved oxygen that exceeds the saturation solubility is gasified in the gas dissolving liquid, and the dissolved oxygen contained in the gas dissolving liquid is reduced. It can be considered that this causes the reduction in the UFB concentration of the UFB-containing liquid generated in the present embodiment.
Here is described a comparative example of the second embodiment. In the comparative example, the UFB-containing liquid generating apparatus 1002 having the same configuration described in the second embodiment is used to generate the UFB-containing liquid by setting both the temperatures of the gas dissolving tank 1101 and UFB generating unit 1113 at a normal temperature (25° C.). The conditions other than the temperatures are the same as that of <Example (2) of Generating UFB-Containing Liquid> in the second embodiment.
The concentration of the generated UFBs in the UFB-containing liquid generated was measured by SALD7500nano (manufactured by SHIMADZU CORPORATION). As a result, it was confirmed that the concentration of the UFBs of 1 μm or smaller in the generated UFB-containing liquid was about 1 billion pieces/mL, and the average particle diameter was 110 nm. From this result, it was found that it is possible to efficiently generate a highly concentrated UFB-containing liquid by performing temperature control like the above-described embodiment.
In the above-described embodiments, examples of using the method of using a nozzle portion and the T-UFB generating method are described as the UFB generating method in the UFB generating unit; however, it is not limited thereto. The present embodiment is also effective in a case of using another UFB generating method.
In the above-described embodiments, an example of performing temperature control using a corresponding temperature controlling unit if there are provided multiple temperature controlling units is described; however, it is not limited thereto. Even there are provided multiple temperature controlling units, the temperature of the UFB generating unit may be controlled to be equal to or lower than the temperature of the gas dissolving tank by executing at least the temperature control by the temperature controlling unit cooling the UFB generating unit. As long as the UFB generating unit is sufficiently cooled, the temperature of the UFB generating unit may be controlled to be equal to or lower than the temperature of the gas dissolving tank by executing the temperature control of the gas dissolving tank.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2021-066520, filed Apr. 9, 2021, which is hereby incorporated by reference wherein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-066520 | Apr 2021 | JP | national |
