JP7765800B2 - Fine bubble supply device - Google Patents

Description

This invention relates to a fine bubble supply device used in laboratories or measurement sites to stably convert artificial gas from a small gas cylinder into fine bubbles and introduce them into a measurement target, such as a relatively small amount of liquid, to expel and replace the dissolved gas, thereby obtaining accurate measurement data.

When raising fish in closed fish pens or tanks, the dissolved oxygen concentration in the water decreases due to the fish's breathing. Therefore, to maintain an appropriate dissolved oxygen concentration, oxygen gas or air is introduced into the water by blowing it in, thereby increasing the dissolved oxygen concentration.

Furthermore, in the water treatment industry, such as boiler water and circulating cooling water, dissolved oxygen can cause pipe corrosion. To remove this dissolved oxygen, nitrogen gas is blown into the water to replace the dissolved oxygen with nitrogen.

Fine bubbles (microbubbles with diameters on the order of 1 to 10 μm, e.g., several tens of μm, or nanobubbles with diameters of several tens to 1,000 nm) are used to efficiently introduce and replace these gases. Known methods for generating fine bubbles include high-speed shearing, pressurized collapse, cavitation, and aspirator. For example, Patent Document 1 discloses a deoxygenation device that reduces or removes dissolved oxygen from specific water, such as underwater or seawater, by circulating nitrogen gas in a nanobubble state through the water and replacing the dissolved oxygen with nitrogen. The device includes a nitrogen gas injection unit that injects nitrogen gas into the water to be treated, and a stack of multiple plates, each plate having a flat surface through which the nitrogen-injected water passes, with multiple holes arranged in the plate's upper and lower grooves in the direction of the hole arrangement, and the upper and lower grooves intersecting at the holes.

Among the methods for generating fine bubbles, the aspirator method is particularly widely used. Patent Document 2 discloses a microbubble generator for use with the aspirator method, which includes a casing with one end opening and the other end opening at each longitudinal end, a gas-liquid mixing means for introducing gas into the casing, a flow straightening cylinder installed inside the casing (4), a first propeller-type blade row fixed to the outside of the flow straightening cylinder, and a second propeller-type blade row fixed to the inside of the flow straightening cylinder.

This type of aspirator method generates fine bubbles by drawing in air or artificial fine bubble-forming gas from a gas cylinder or the like into the water flow passing through the aspirator. These bubbles can be used in a wide range of applications, from large to small, including fish pens, pools, aquariums, and laboratory containers. Because the aspirator's structure is relatively simple, there is no need for a complex and expensive fine bubble generator, and fine bubbles can be introduced cheaply and easily.

When using the aspirator method to sufficiently dissolve fine bubbles from introduced gas into a specified amount of water, one approach is to increase the amount of fine bubbles generated and introduced per specified time. Patent Document 2 states that there is a limit to the amount of fine bubbles (microbubbles) that can be generated per specified time, and that in practice, the upper limit for the liquid flow rate is approximately 15 to 30 liters per minute, and that the volume of gas in the liquid is said to be in the range of approximately 1 to 10 percent in terms of void fraction.

In the aspirator method, when the gas to be aspirated is air drawn in from the ambient atmosphere surrounding the device, a gas flow regulator and, if necessary, a gas flow meter and pressure gauge are used to adjust the amount of gas supplied to the aspirator. Such a gas flow regulator uses a needle valve. The needle valve adjusts the flow rate by changing the degree of opening of the conical needle-type release valve, and adjustments are made using a gas flow meter and pressure gauge.

Fine bubbles are generated by drawing a fixed amount of large volumes of introduced gas into the aspirator per unit of time, such as atmospheric air or artificial gases such as oxygen, nitrogen, or argon gas from an outdoor nitrogen gas tank or large gas cylinder (a 47-liter gas cylinder containing approximately 7,000 liters of gas at atmospheric pressure, a 40-liter gas cylinder containing approximately 6,000 liters, or a 10-liter gas cylinder containing approximately 1,500 liters). Even when a sufficient amount (e.g., 0.5 to 5 liters per minute) of introduced gas, such as atmospheric air or artificial gas from an outdoor nitrogen gas tank or large gas cylinder, is drawn into the aspirator, there is little or no change in the supply gas pressure or flow rate per unit of time. Therefore, once the gas flow rate is adjusted with the needle valve, there is no need to readjust it.

However, when an artificial gas such as oxygen, nitrogen or argon gas is introduced into an aspirator at a rate of, for example, 0.5 to 5 liters per minute from a relatively small-capacity small gas cylinder (a 3.4 liter gas cylinder containing approximately 500 liters at normal pressure) or a handy mini gas cartridge, commonly known as a spray can (a 10 mL mini gas cartridge containing approximately 4.4 liters, a 15 mL mini gas cartridge containing approximately 6.6 liters, a 60 mL mini gas cartridge containing approximately 20 to 26 liters, or a 95 to 98 mL mini gas cartridge containing approximately 18 to 40 liters depending on the type of gas), the internal pressure of the cartridge gradually decreases, causing the flow rate per unit time to fluctuate and temporarily decrease; or, because the internal pressure is not very high, the flow rate per unit time will fluctuate sequentially in accordance with fluctuations in the external temperature and the operating pressure of the ejection valve. In such cases, it is extremely difficult to uniformly adjust the gas flow rate by simply adjusting the degree to which the jet valve is opened or adjusting the flow rate midway through the flow path with a needle valve.

If it were possible to adjust the degree of release of the spray valve on a small gas cylinder or mini gas cartridge in real time based on the flow rate measurement results from the small gas cylinder or mini gas cartridge, or to adjust the flow rate with a needle valve midway through the flow path, a large-scale adjustment mechanism would be required, making it impractical for a simple and compact aspirator-type fine bubble generator.

Japanese Patent Application Laid-Open No. 2015-116555 Japanese Patent Application Laid-Open No. 2007-21343

The present invention has been made to solve the above-mentioned problems, and aims to provide a simple, easy-to-use aspirator-type fine bubble supply device that can stably and efficiently generate a constant amount of fine bubbles per unit time using artificial gas from an artificial gas supply source such as a small-capacity gas cylinder or mini gas cartridge, and that supplies a small amount of fine bubbles to a measurement target.

The fine bubble supply device made to achieve the above object is:
A fine bubble supply device in which an artificial gas is drawn from an artificial gas supply source, which is a gas cylinder or gas cartridge or a spray can containing an artificial gas, and fine bubbles are generated by drawing the artificial gas from an artificial gas supply source , which is an artificial gas supply source, a gas cylinder or gas cartridge or a spray can, via an aspirator that is connected so as to draw the liquid from a liquid measurement object portion , which is made of a sample solution and placed in an open measurement object container, and then the liquid is supplied to the measurement object portion by the liquid supply pump,
The present invention is characterized in that a variable-volume buffer container is provided in the middle of the flow path between the artificial gas supply source and the aspirator, and the variable-volume buffer container is made of either a bag made of flexible resin film that expands or contracts so that the pressure of the artificial gas is equalized with atmospheric pressure, which is the ambient pressure of the measurement object part, or a piston syringe with a movable piston slidably inserted into a cylinder, thereby changing the volume so that the pressure is equalized with atmospheric pressure .

It is preferable that this fine bubble supply device has a regulator in the flow path between the variable volume buffer container and the artificial gas supply source, which regulates the flow rate of the artificial gas by the degree of opening of a flow control valve so that the pressure inside the variable volume buffer container is equal to the atmospheric pressure and the volume of the artificial gas inside the variable volume buffer container is maintained within a certain range .

This fine bubble supply device may have a regulator in the flow path between the variable volume buffer container and the artificial gas supply source, which supplies or increases the amount of artificial gas to the variable volume buffer container when the volume of the artificial gas falls below a lower threshold, while maintaining the pressure inside the variable volume buffer container at equal pressure with the atmospheric pressure, and stops or reduces the supply of the artificial gas when the volume exceeds an upper threshold.

This fine bubble supply device may have a mass flow controller in the flow path between the variable volume buffer container and the aspirator, which adjusts the pressure in the variable volume buffer container to be equal to the atmospheric pressure and adjusts the volume of the artificial gas in the variable volume buffer container to be constant.

This fine bubble supply device may be configured such that the variable capacity buffer container has an overflow mechanism that releases the artificial gas in the variable capacity buffer container to the outside world when its volume exceeds a predetermined amount until it reaches a predetermined volume.

It is preferable that this fine bubble supply device has a check valve in the overflow mechanism or in the excess gas exhaust line branching off from between the variable volume buffer container and the artificial gas supply source in the flow path to prevent backflow of outside air.

The fine bubble supply device of the present invention traps the artificial air pressure in a variable-capacity buffer container and equalizes it with the ambient pressure, even if the flow rate of artificial gas supplied from an artificial gas supply source such as a small-capacity gas cylinder or mini gas cartridge fluctuates over time or temporarily. This ensures that a constant amount of artificial gas is supplied to the aspirator per unit time, allowing the aspirator to stably and efficiently generate a constant amount of fine bubbles per unit time.

This fine bubble supply device does not necessarily require the use of a gas flow meter or pressure gauge, and does not require the need to adjust the degree of opening of the artificial gas supply source's jet valve in real time or adjust the flow rate with a needle valve midway through the flow path. It can be configured simply and easily, and can reliably control the gas flow rate, stably and efficiently generating a constant amount of fine bubbles per unit time.

This fine bubble supply device is equipped with a variable-capacity buffer container that can buffer even slight fluctuations in the gas flow rate, eliminating the need to constantly adjust the gas flow rate from the artificial gas supply source using complicated methods such as measuring the gas flow rate and providing feedback. Even when the measurement target area is small, such as in lab-scale measurements or on-site measurements in the ocean, rivers, or lakes, the dissolved gas in the measurement target area, such as dissolved oxygen, can be reliably replaced with fine bubbles from the artificial gas.

This fine bubble supply device is highly versatile, as it can be constructed using a simple, readily available variable-volume buffer container such as a bag, cylinder, or piston, while also using a general-purpose aspirator or liquid delivery pump that can be commercially available or manufactured as needed.

This fine bubble supply device can stably and efficiently generate a constant amount of fine bubbles per unit time, whether at normal pressure, under high-pressure conditions such as in the ocean or on the seabed, or under low-pressure conditions such as at high altitudes, so it can be used to reliably and accurately measure the target area regardless of location or environment.

1 is a schematic diagram showing a fine bubble supply device to which the present invention is applied. FIG. 1 is a plan view showing an aspirator of a fine bubble supply device to which the present invention is applied. FIG. 1 is a schematic diagram showing another embodiment of a fine bubble supplying device to which the present invention is applied. FIG. 1 is a schematic perspective view showing a variable-volume buffer container of a fine bubble supplying device to which the present invention is applied. FIG. 10 is a plan view showing another embodiment of a variable-volume buffer container of the fine bubble supply device to which the present invention is applied. FIG. 10 is a plan view showing another embodiment of a variable-volume buffer container of the fine bubble supply device to which the present invention is applied. FIG. 10 is a schematic diagram showing a part of a fine bubble supplying device according to another embodiment of the present invention. FIG. 10 is a schematic diagram showing the state of use of a fine bubble supplying device according to another embodiment of the present invention. FIG. 10 is a schematic diagram showing the state of use of a fine bubble supplying device according to another embodiment of the present invention.

The following describes in detail the embodiments of the present invention, but the scope of the present invention is not limited to these embodiments.

Referring to Figure 1, which shows a schematic diagram of the fine bubble supply device 1 of the present invention, artificial fine bubbles 12 are introduced into a liquid measurement object 11, such as a sample solution, to replace dissolved gas, such as dissolved oxygen, in the measurement object 11 with the artificial gas.

This fine bubble supply device 1 is connected to a liquid measurement target 11 and includes a liquid delivery pump 20, an aspirator 30, a variable-volume buffer container 40, and an artificial gas supply source 50.

This fine bubble supply device 1 is specialized for introducing fine bubbles 12 of artificial gas into a liquid measurement object 11, typically a maximum of 1 L, preferably 1 mL to 500 mL, more preferably 3 to 250 mL, specifically 5 to 200 mL, using an artificial gas supply source 50 such as a small gas cylinder containing a maximum of approximately 500 L of artificial gas, preferably 20 to 40 L at room temperature, or a mini gas cartridge containing only approximately 5 L.

In this fine bubble supply device 1, it is preferable that the variable-volume buffer container 40 and the artificial gas supply source 50 are always connected, but it is also possible to separate or block the artificial gas supply source 50 from the variable-volume buffer container 40 after a sufficient amount of artificial gas has been introduced from the artificial gas supply source 50 into the variable-volume buffer container 40.

Artificial gases include nitrogen gas, argon gas, helium gas, oxygen gas, carbon dioxide gas, ammonia gas, and mixtures of any two or more of these gases.

The sample solution, which is the liquid measurement object 11, is contained in an open measurement object container 10, such as a beaker. An intake tube 21, which draws in the sample solution 11, is connected to a liquid delivery pump 20. An outlet tube 22 extends from the liquid delivery pump 20, sending the liquid solution to an aspirator 30. The outlet tube 22 is connected to the aspirator 30 via an aspirator inlet connector 31. The sample solution flow path 32 narrows within the aspirator 30 at the aspirator inlet connector 31, and continues to the aspirator outlet connector 33. Inside the aspirator 30, the sample solution flow path 32 merges with an artificial gas intake flow path 35. An outlet tube 36, whose diameter expands at the aspirator outlet connector 33 connected to the sample solution flow path 32, extends from the aspirator 30, with its open end 36a immersed in the sample solution 11 in the measurement object container 10.

Meanwhile, an artificial gas supply source 50, such as a small gas cylinder or mini gas cartridge, is connected via piping tube 54 to a regulator 53 having a flowmeter or pressure gauge 52 and a main valve 51 for adjusting the opening and closing of the gas. If necessary, a flow control valve 55, such as a needle valve, is provided along the piping tube 54. The piping tube 54 branches off at a T-shaped pipe 56 and connects to a branch tube 41. The branch tube 41 is inserted into an airtight variable-capacity buffer container 40, such as a sealed bag, via a variable-capacity buffer container inlet connector 42. The variable-capacity buffer container inlet connector 42 and the variable-capacity buffer container 40 are heat-sealed, so that the tip hole 41a of the branch tube 41 communicates with the interior of the variable-capacity buffer container 40 while preventing leakage to the outside. If necessary, a check valve 57 is provided along the piping tube 54. The tip of the piping tube 54 is connected to the aspirator 30, where the piping tube 54 is connected to the artificial gas suction flow path 35 via the aspirator inlet connector 34.

The aspirator 30 is also known as an aspirator or ejector type, and generates fine bubbles using the principle of sucking an external fluid into a high-pressure fluid through a constriction or nozzle. As shown in the cross-sectional view of the sample solution flow path 32 and the artificial gas intake flow path 35 in Figure 2, the aspirator 30 has the artificial gas intake flow path 35 joining the straight sample solution flow path 32 from a diagonal rearward side toward the downstream end of the flow path, making it easier to entrain the artificial gas from the artificial gas intake flow path 35 into the sample solution flow path 32. While Figure 2 shows an example in which the artificial gas intake flow path 35 joins the sample solution flow path 32 from a diagonal side, a T-shaped vertical merger is also possible (not shown). The inner diameters of the sample solution flow path 32 and the artificial gas intake flow path 35 are not particularly limited as long as the aspirator 30 uses a water jet to entrain the artificial gas and generate fine bubbles. However, because this fine bubble supply device 1 uses an artificial gas supply source 50 such as a small gas cylinder or mini gas cartridge to introduce fine bubbles into a small amount of liquid measurement target 11, it is preferable that the inner diameters of the sample solution flow path 32 and the artificial gas intake flow path 35 are not too large. Specifically, the inner diameters of the intake tube 21, the delivery tube ₂₂ , the outlet tube 36, and the piping tube 54 are _{each 0.5} to 10 mm, preferably 1 to 5 mm, more preferably 1 to 3 mm, or specifically 2 mm, while the inner diameters _W2 of the sample solution flow path 32 and _W5 of the artificial gas intake flow path 35 are 0.05 to 1 mm, preferably 0.1 to 0.5 mm, more preferably 1 to 0.25 mm, or specifically 0.2 mm.

Such an aspirator 30 is made of a transparent hard resin, such as polycarbonate (PC) or acrylic (PMMA), or an opaque hard resin, such as polyether ether ketone (PEEK), and can be fabricated by bonding a hard resin plate into which the sample solution flow path 32 and artificial gas intake flow path 35 are engraved to a flat hard resin plate, by three-dimensional printing molding, or by drilling holes for the sample solution flow path 32 and artificial gas intake flow path 35.

The artificial gas fine bubbles 12 formed by this aspirator 30 are minute bubbles with diameters of approximately 100 nm to 10 μm, or roughly 1 μm.

The variable-volume buffer container 40 is not particularly limited as long as it is airtight and can constantly trap the artificial gas, but a preferred example is an airtight bag made of flexible resin film. The variable-volume buffer container 40 traps the artificial gas and equalizes it with atmospheric pressure, while buffering fluctuations and changes over time in the flow rate and pressure of the artificial gas from the artificial gas supply source 50, so that a constant amount of artificial gas can be delivered to the aspirator 30 per unit time. This makes it possible to deliver a constant amount of fine bubbles made of artificial gas per unit time to the aspirator 30, even when using an artificial gas supply source 50 such as a small gas cylinder or mini gas cartridge, whose flow rate and pressure fluctuate and change over time over a short period of use.

The variable-volume buffer container 40 has a flow control valve 55 that adjusts the flow rate of the artificial gas depending on the degree of release, allowing the volume of the artificial gas within the variable-volume buffer container 40 to be maintained within a constant range. The flow control valve 55 may be adjusted manually or automatically so that the bag that is the variable-volume buffer container 40 is inflated with the artificial gas during measurement of the liquid measurement object 11. For example, in this case, a needle valve, solenoid valve, or ball valve is used as the flow control valve 55. While the flow control valve 55 is illustrated in Figure 1, a flow meter (mass flow meter: MFM) may be used instead of or in addition to the flow control valve 55. The flow control valve 55 may be adjusted by a drive circuit according to the reading of the mass flow meter 58, or an MFC (mass flow controller) may be used.

Another example of adjusting the variable volume of the variable volume buffer vessel 40 is to measure the volume of the artificial gas flowing into the aspirator 30 using a mass flow meter (MFM) 58 (see Figure 1), which is provided as needed, and then control the degree of opening of the flow control valve 55 using a drive circuit according to the reading of the mass flow meter 58 so that only the volume of artificial gas recognized by the digital conversion circuit flows into the bag or piston syringe that constitutes the variable volume buffer vessel 40, thereby adjusting the volume of the variable volume buffer vessel 40 to a constant level. A flow control valve 55 that adjusts the flow rate using a drive circuit according to the reading of the mass flow meter 58 may be located between the mass flow meter 58 and the variable volume buffer vessel 40, and an auxiliary pump may also be located on the variable volume buffer vessel 40 side.

The system may also include a regulator that supplies artificial gas to the variable-volume buffer container 40 when the volume of the artificial gas in the variable-volume buffer container 40 falls below a lower threshold and stops supplying artificial gas when the volume exceeds an upper threshold. When the variable-volume buffer container 40 is a bag, the regulator, as shown in FIG. 3, has pressure sensors installed inside and outside the bag. When the outside of the bag (the variable-volume buffer container 40) touches the pressure sensors, it detects an upper limit, and when the inside of the bag touches the pressure sensors, it detects a lower limit. This allows the regulator to sense upper and lower volume thresholds. When a comparison circuit detects that the upper threshold is exceeded, the drive circuit closes or tightens the flow control valve 55. Conversely, when the comparison circuit detects that the lower threshold is exceeded, the drive circuit opens or loosens the flow control valve 55. Preferably, the volume of the variable-volume buffer container 40 is monitored, and the flow control valve 55 is turned on and off to maintain the volume between the upper and lower thresholds. For example, as shown in Figures 11(a) to 11(c), the pressure sensor may be configured with an electrode pair consisting of an electrode 46b arranged on the upper exterior of the bag of the variable-capacity buffer container 40 and an electrode 46a arranged above the bag, which senses the upper threshold when the electrodes 46a and 46b come into contact with each other when the volume of the artificial gas exceeds the upper threshold and the bag becomes excessively inflated, and an electrode pair consisting of an electrode 46c arranged inside the upper surface of the bag and an electrode 46d arranged inside the lower surface of the bag, which senses the lower threshold when the electrodes 46c and 46d come into contact with each other when the volume of the artificial gas falls below the lower threshold and the bag becomes excessively deflated. Alternatively, although not shown, the pressure sensor may be a capacitance-type pressure sensor that detects pressure based on changes in capacitance caused by applied force (for example, a force pushing up on the sensor when the bag is over-inflated or gravity due to a weight when the bag is over-deflated) instead of an electrode pair, or a pressure-sensitive conductive rubber-type pressure sensor that detects pressure based on a decrease in resistance in response to applied force by mixing a conductive material with insulating rubber. The pressure sensor may be a 1-axis, 3-axis, or 6-axis force sensor that detects forces in the length, width, and height directions, moment plane, and action, a capacitance-type force sensor that detects shape distortion of the bag caused by applied force or moment based on changes in the capacitance of a capacitor, or a strain gauge-type force sensor that uses a strain gauge sensor to detect shape distortion of the bag caused by applied force or moment.

Alternatively, as shown in Figure 4, an image of the variable-volume buffer container 40 is taken with a camera 47, and the image is compared with control images taken in advance, ranging from a deflated state to an over-inflated state. Through image recognition, when it is determined that the bag that constitutes the variable-volume buffer container 40 is over-inflated, as shown in Figure 4(a), the drive circuit closes or tightens the flow control valve 55, and when it is determined that the bag is deflated, as shown in Figure 4(c), the drive circuit opens or loosens the flow control valve 55, thereby keeping the volume of the artificial gas inside the variable-volume buffer container 40 within a certain range.

While a bag has been used as an example of the variable-volume buffer container 40, it may also be an airtight resin, metal, or glass piston syringe connected to a branch tube 41, with a plunger 44 fitted with a rubber gasket 44a at its tip slidably inserted within an outer cylinder 43, as shown in FIG. 5(a). Alternatively, it may be an airtight resin or metal piston syringe connected to a branch tube 41, with a movable piston 44' slidably inserted within a cylinder 43', as shown in FIG. 5(b). One example of adjusting the volume of the piston syringe serving as the variable-volume buffer container 40 is to have a position sensor that detects the position of the plunger 44 or piston 44'. When a position sensor detects that the upper threshold position has been exceeded, the drive circuit closes or tightens the flow control valve 55, and when a position sensor detects that the lower threshold position has been exceeded, the drive circuit opens or loosens the flow control valve 55. Instead of a position sensor, the upper and lower threshold positions may be determined using image recognition.

The maximum variable capacity of the variable-volume buffer container 40 is, for example, 10 mL to 10 L, preferably 50 mL to 1 L, and specifically 100 to 200 mL.

1 to 5, as shown in FIG. 6, the piping tube 54, the variable volume buffer container 40, and/or the branch tube 41 may have an overflow mechanism that releases the artificial gas to the outside when the volume of the artificial gas in the variable volume buffer container 40 exceeds a predetermined amount, until the artificial gas reaches a predetermined amount. For example, as shown in FIG. 6(a), the variable volume buffer container 40 may be a piston syringe, and at the portion where the plunger 44 or piston exceeds a predetermined upper limit position, the outer tube 43 or cylinder may be provided with a check valve directly as an overflow mechanism 45 that releases excess artificial gas but prevents backflow of outside air, or an open hole and a check valve connected to it. Also, as shown in FIG. 6(b), the variable volume buffer container 40 may be a bag, and as an overflow mechanism 45 (45') that opens when excessive pressure is reached, a check valve may be directly provided, or an open hole and a check valve connected to it may be attached to the outer wall of the bag's artificial gas storage section.

As shown in Figure 7, the excess gas exhaust line may have a check valve 56 to prevent backflow of outside air.

The artificial gas supply source 50 contains 500 L or less at atmospheric pressure equivalent, and can be a small gas cylinder (3.4 L capacity, which contains approximately 500 L at atmospheric pressure equivalent) or a handy mini gas cartridge, commonly known as a spray can (10 mL capacity, which contains approximately 4.4 L; 15 mL capacity, which contains approximately 6.6 L; 60 mL capacity, which contains approximately 20-26 L; or 95-98 mL capacity, which contains approximately 18-40 L).

Since this fine bubble supply device 1 supplies fine bubbles to a small amount of the measurement target area 11, the artificial gas supplied from the artificial gas supply source 50 is adjusted to flow at approximately 1 to 1000 mL/min, preferably 5 to 200 mL/min, and more preferably 10 to 50 mL/min. The artificial gas is adjusted to a flow rate per unit time of approximately 2 to 1/100, preferably 1/2 to 1/10, of the sample solution circulated by the liquid delivery pump 20.

The liquid delivery pump 20 is not particularly limited as long as it can draw in sample solution from the intake tube 21 and deliver it from the delivery tube 22. Examples include a peristaltic pump, which delivers liquid by squeezing the intake tube 21, a soft tube made of silicone or the like, with a roller; an impeller pump; a diaphragm pump; a bellows pump; and a syringe pump. The liquid delivery pump 20 may be either a pulsating or non-pulsating type, although a non-pulsating type is preferred. Because the liquid delivery pump is designed to deliver a small amount of liquid to the measurement target 11, it is capable of delivering a flow rate of 1 to 500 mL/min, preferably 20 to 200 mL/min, and more specifically, approximately 100 mL/min.

Referring to the diagram, the fine bubble supply device 1 is used as follows: First, a sample solution, which is the liquid measurement target portion 11, is placed in the measurement target container 10. Next, the pump 20 is driven to draw in the sample solution through the intake tube 21 and deliver it through the delivery tube 22. The sample solution then passes through the aspirator 30 and is returned to the measurement target container 10 through the delivery tube 36. Meanwhile, when the main valve 51 of the artificial gas supply source 50 is opened and a predetermined amount of artificial gas is allowed to flow through the piping tube 54 while being adjusted with a flowmeter or pressure gauge 52, the artificial gas accumulates in the variable-volume buffer container 40 and reaches the aspirator 30. It is then drawn into the sample solution flow path 32 via the artificial gas intake flow path 35, forming fine bubbles of the artificial gas. Fine bubbles 12 are then drawn into the measurement container 10 along with the sample solution from the open end 36a of the outlet tube 36, and the artificial gas gradually dissolves in the sample solution due to the fine bubbles 12, eventually replacing the artificial gas. At this time, the artificial gas is adjusted to a nearly constant level in the variable-volume buffer container 40 using one of the methods shown in Figures 3 to 7.

The fine bubble supply device 1 is useful for introducing a small amount of artificial gas fine bubbles from a small artificial gas supply source into the measurement target area, buffering the gas in the variable-volume buffer container 40 while replacing dissolved gas with artificial gas. However, it is not suitable for introducing a large amount of fine gas bubbles from a large artificial gas supply source (the atmosphere, a gas tank, or a large gas cylinder) into a swimming pool or fish pen. This is because when a large artificial gas supply source is used, pressure and flow fluctuations are unlikely to occur in a short period of time, making the use of a variable-volume buffer container 40 unnecessary and, in fact, making it more complicated and not providing the desired effect.

In Figure 1 and other figures, an example is shown in which fine bubbles of an artificial gas, such as nitrogen gas, are introduced into a liquid sample solution (specifically, a sample aqueous solution or sample suspension) in an open-system measurement container 10, such as a beaker, in an indoor laboratory or measurement room to expel and replace dissolved oxygen. However, the measurement target can also be the measurement environment at the measurement site, such as the seabed, ocean, underwater, lakes, or rivers. In such cases, a liquid can be drawn from a surrounding environment deemed to have the same water quality as the measurement target using a liquid delivery pump, and fine bubbles can be introduced into the measurement target. For example, as shown in Figure 8(a), an underwater condition measurement device 60 equipped with a fine bubble supply device 1 is deployed from a ship into the sea. When various data are measured at a desired depth, the fine bubble supply device 1 is activated to supply fine bubbles to the seawater being measured by various sensors. This allows for measurements of various parameters of seawater at specified depths in the ocean, specifically, accurate measurements of parameters such as carbon dioxide partial pressure by replacing the air with fine bubbles of nitrogen gas. Furthermore, as shown in Figure 1(b), a spear-shaped external cylinder 70 containing a built-in monitoring sensor and a seafloor subsurface condition monitoring device 71 containing a built-in fine bubble supply device 1 are used. The spear-shaped external cylinder 70 is pierced into the seafloor soil, and the seafloor subsurface condition monitoring device measures the circulation status and physicochemical properties of seafloor groundwater in the soil below the seafloor, as well as the methane gas concentration of seafloor methane hydrate. The fine bubble supply device 1 can be driven to supply fine bubbles to the seawater being measured by various sensors, replacing the seawater with fine bubbles containing nitrogen gas, allowing for accurate measurement of items such as methane gas concentration. This system can also be applied to aqueous solutions and suspended water, as well as supercritical water. Note that Figures 1(a) and 1(b) do not show the artificial gas supply source, variable-volume buffer vessel, intake tube, delivery tube, and piping tube, as they are hidden.

Below, we will explain a fine bubble supply device in an embodiment to which the present invention is applied, and a fine bubble supply device in a comparative example to which the present invention is not applied.

Example 1
The fine bubble supply device 1 shown in Figure 1 uses a 500 mL mini-gas cartridge containing approximately 4.5 L of nitrogen gas (equivalent to atmospheric pressure) as the artificial gas supply source 50, a Tedlar bag (manufactured by AS ONE Corporation; Tedlar is a registered trademark) made of polyvinyl fluoride resin as the variable-volume buffer container 40, a peristaltic pump as the pump, a needle valve as the flow control valve 55, and a needle valve and flow meter (mass flow meter) as the flow control valve 58. 100 mL of tap water was used as the sample solution for measurement 11, and the needle valve and flow meter of the flow control valve 58 were linked to expel dissolved oxygen while adjusting the flow rate to 20 mL/min, as shown in Figure 1. To measure the dissolved oxygen concentration in the sample solution, a dissolved oxygen sensor (manufactured by Mettler Toledo: product name Seven2Go DO meter S9) was inserted into the sample solution. The fine bubble supply device 1 was operated, and the fine bubble-coexisting sample solution was circulated through the sample solution. The correlation between the elapsed time and the dissolved oxygen concentration is shown in Figure 9(a). The right side of Figure 9(a) is an enlarged view of the dissolved oxygen concentration shown in the left side of the figure.

As is clear from Figure 9(a), the dissolved oxygen concentration of the sample solution was initially approximately 7 mg/L, but this decreased to approximately 1 mg/L two minutes after the fine bubble supply device 1 started operating, to approximately 0.1 mg/L after four minutes, and to 0.01 mg/L after six minutes.

(Comparative Example 1)
The dissolved oxygen concentration of 100 mL of tap water sample solution was measured in the same manner as in Example 1, except that the variable-volume buffer container 40 was not used. The results are shown in Figure 9(b). The right graph in Figure 9(b) is an enlarged view of the dissolved oxygen concentration of the left graph.

As is clear from Figure 9(b), the dissolved oxygen concentration of the sample solution was initially approximately 7 mg/L. 2 minutes after the fine bubble supply device 1 started operating, this had decreased to approximately 1 mg/L, as in Figure 9(a). After 4 minutes, it had decreased to approximately 0.25 mg/L, and after 6 minutes, it had decreased to approximately 0.12 mg/L. Compared to Figure 9(a), the rate of decrease was slower. This is thought to be due to the fact that, since the variable-volume buffer container 40 was not used, the gas supply pressure decreased during operation of the device, resulting in a decrease in the gas supply amount.

Therefore, as is clear from Figures 9(a) and (b), the use of the variable-volume buffer container 40 was effective.

The fine bubble supply device of the present invention introduces a small amount of artificial fine bubbles from a small artificial gas supply source into the measurement target area, replacing dissolved gas with the artificial gas and eliminating the effects of the dissolved gas, making it useful for performing various physical and chemical analyses of the measurement target area.

Reference numeral 1 denotes a fine bubble supply device, 10 denotes a container for the measurement object, 11 denotes a measurement object (sample solution), 12 denotes fine bubbles, 20 denotes a liquid delivery pump, 21 denotes an intake tube, 22 denotes an output tube, 30 denotes an aspirator, 31 denotes an aspirator liquid inlet connector, 32 denotes a sample solution flow path, 33 denotes an aspirator liquid outlet connector, 34 denotes an aspirator gas inlet connector, 35 denotes an artificial gas intake flow path, 36 denotes an outlet tube, 36a denotes an open end, 40 denotes a variable capacity buffer container, 41 denotes a branch tube, 42 denotes a variable capacity buffer Container air inlet connector, 43 is an outer tube, 43' is a cylinder, 44 is a plunger, 44' is a piston, 45 and 45' are overflow mechanisms, 46a to 46d are electrodes, 47 is a camera, 50 is an artificial gas supply source, 51 is a main valve, 52 is a flow meter or pressure gauge, 53 is a regulator, 54 is a piping tube, 55 is a flow control valve, 56 is a T-pipe, 57 is a check valve, 58 is a mass flow meter, 60 is an underwater situation measuring device, 70 is a spear-shaped outer tube and monitoring sensor, 71 is a seabed underground situation monitoring device, and W ₁ to W ₅ are inner diameters.

Claims (6)

A fine bubble supply device in which an artificial gas is drawn from an artificial gas supply source, which is a gas cylinder or gas cartridge or a spray can containing an artificial gas, and fine bubbles are generated by drawing the artificial gas from an artificial gas supply source , which is an artificial gas supply source, a gas cylinder or gas cartridge or a spray can, via an aspirator that is connected so as to draw the liquid from a liquid measurement object portion , which is made of a sample solution and placed in an open measurement object container, and then the liquid is supplied to the measurement object portion by the liquid supply pump,
A fine bubble supply device characterized by having, in the middle of the flow path between the artificial gas supply source and the aspirator, a variable-capacity buffer container consisting of either a bag made of flexible resin film that expands or contracts so that the pressure of the artificial gas is equal to atmospheric pressure, which is the ambient pressure of the measurement object, or a piston syringe with a movable piston slidably inserted into a cylinder, thereby changing the volume so that the pressure is equal to atmospheric pressure . 2. The fine bubble supply device according to claim 1, further comprising a regulator in the flow path between the variable volume buffer container and the artificial gas supply source, which regulates the flow rate of the artificial gas by adjusting the degree of opening of a flow control valve so that the pressure in the variable volume buffer container is equal to the atmospheric pressure and the volume of the artificial gas in the variable volume buffer container is maintained within a certain range. The fine bubble supply device according to claim 2, characterized in that the regulator is provided in the flow path between the variable volume buffer container and the artificial gas supply source, and the regulator supplies or increases the amount of the artificial gas to the variable volume buffer container when the volume of the artificial gas falls below a lower threshold, while maintaining the pressure inside the variable volume buffer container equal to the atmospheric pressure, and stops or reduces the supply of the artificial gas when the volume exceeds an upper threshold . The fine bubble supply device according to claim 1, further comprising a mass flow controller in the flow path between the variable volume buffer container and the aspirator, which adjusts the pressure in the variable volume buffer container to be equal to the atmospheric pressure and adjusts the volume of the artificial gas in the variable volume buffer container to be constant. The fine bubble supply device according to claim 1, characterized in that the variable-volume buffer container has an overflow mechanism that releases the artificial gas in the variable-volume buffer container to the outside when its volume exceeds a predetermined amount until it reaches a predetermined volume. The fine bubble supply device according to claim 5 , characterized in that the overflow mechanism or the excess gas exhaust line branching off from between the variable volume buffer container and the artificial gas supply source in the flow path has a check valve to prevent backflow of outside air.