Gas-dissolved liquid generation device and gas-dissolved liquid generation method

Abstract

This gas-dissolved liquid generation device 1 comprises: a pump 2 that suctions a liquid; an ejector 3 that is disposed on a primary side of the pump 2 and injects a gas into a flow of the liquid introduced by the suction to eject a gas-dissolved liquid; a buffer tank 4 capable of storing the gas introduced by suction or a liquid flowing back from a gas suction part of the ejector; and a discharge line 5 that discharges the liquid from the buffer tank 4 to a primary-side suction line 7 of the pump 2.

Description

Gas-dissolved liquid generating device and gas-dissolved liquid generating method

[0001] The present invention relates to a method for generating a gas-dissolved liquid and an apparatus therefor.

[0002] Examples of ozone water generating devices that dissolve ozone gas in water to generate ozone water include ejector-type devices such as those disclosed in Patent Documents 1 and 2.

[0003] In an ejector-type ozone water generating device, when a negative pressure occurs in the ozone generating device connected to the suction port of the ejector, the probability of a decrease in ozone gas generation capacity and malfunctions of the ozone generating device increases. Therefore, the ozone water generating device of Patent Document 1 provides an orifice between the ozone generating device and the ejector to keep the ozone gas generating part of the ozone generating device at a positive pressure, and supplies ozone gas to the ejector under the same pressure.

[0004] The ozone water supply system of Patent Document 2 includes a supply line for ozone water, a circulation line for ozone water, an ozone concentration sensor, and a controller for controlling the generated ozone concentration of an ozone generator, and controls so that fluctuations in ozone concentration due to the discharge of ozone water to the supply line, etc., are eliminated. The ozone gas used as a raw material for ozone water is generated by a discharge-type ozonizer that generates ozone gas by discharging, with oxygen as the main raw material, and the supply pressure is at normal pressure or higher.

[0005] Japanese Patent No. 4746515, Japanese Patent No. 7041466, Japanese Patent No. 4186551, Japanese Patent No. 4118185

[0006] The above prior art generates ozone water by mixing ozone gas and water using a gas-liquid mixing device such as an ejector. The supply pressure of the ozone gas at this time is considered to be a positive pressure.

[0007] On the other hand, there are devices (ozonizers) for generating ozone gas that hold ozone gas at a negative pressure inside the device for the purpose of suppressing the self-decomposition of highly concentrated ozone gas.

[0008] However, if sufficient suction pressure cannot be obtained due to abnormalities in the supply water temperature or circulation pump, water may flow back into the ozone gas supply system and enter the ozone gas flow meter, valves, etc., potentially causing malfunction or failure of the ozone gas supply system.

[0009] In view of the above circumstances, the present invention aims to prevent liquid that has flowed back from the gas suction section of an ejector into the gas supply system when a gas is supplied to the ejector together with a liquid to generate a gas-dissolved liquid.

[0010] One aspect of the present invention is a gas-dissolved liquid generating apparatus comprising: a pump for sucking up liquid; an ejector disposed on the primary side of the pump for injecting gas into the flow of liquid introduced by the suction to discharge a gas-dissolved liquid; a buffer tank capable of storing the gas introduced by suction or the liquid that flows back from the gas suction section of the ejector; and a discharge line for discharging the liquid from the buffer tank to the primary side suction line of the pump.

[0011] One aspect of the present invention is a gas-dissolved liquid generating apparatus in which the buffer tank is positioned directly above the horizontally positioned gas suction section, and an upright gas suction line communicating with the gas suction section is drawn into the buffer tank from the bottom of the buffer tank, and the discharge line is connected to the side surface near the bottom of the buffer tank.

[0012] One aspect of the present invention is a gas-dissolved liquid generating apparatus in which the discharge line includes a valve that discharges the liquid based on the liquid level of the liquid in the buffer tank, the valve starts discharge when the liquid level reaches an upper limit liquid level lower than the gas suction port in the buffer tank, and stops discharge when the liquid level reaches a lower limit liquid level higher than the suction port of the discharge line in the buffer tank.

[0013] In one aspect of the present invention, in the gas-dissolved liquid generating apparatus, the ejector is housed in the buffer tank.

[0014] One aspect of the present invention is a gas-dissolved liquid generating apparatus in which the discharge line includes a valve that discharges the liquid based on the liquid level of the liquid in the buffer tank, the valve starts discharge when the liquid level reaches an upper limit liquid level lower than the gas suction section, and stops discharge when the liquid level reaches a lower limit liquid level higher than the suction port of the discharge line in the buffer tank.

[0015] One aspect of the present invention is a method for producing a gas-dissolved liquid using a gas-dissolved liquid generating apparatus comprising: a pump for sucking up a liquid; an ejector disposed on the primary side of the pump for injecting gas into the liquid introduced by the suction to discharge a gas-dissolved liquid; and a buffer tank capable of storing the gas introduced by suction from the outside or the liquid that has backflowed from the gas suction section of the ejector, the method comprising: a process in which the liquid that has backflowed from the gas suction section is stored in the buffer tank; and a process in which the liquid is discharged from the buffer tank to the primary side suction line of the pump on the discharge side of the ejector.

[0016] According to the present invention described above, when supplying a gas together with a liquid to an ejector to generate a gas-dissolved liquid, it is possible to prevent the liquid that flows back from the gas suction section of the ejector from entering the gas supply system.

[0017] A schematic cross-sectional view of the gas-dissolved liquid generating apparatus according to Embodiment 1, one aspect of the present invention. A schematic cross-sectional view of the gas-dissolved liquid generating apparatus according to Embodiment 2, one aspect of the present invention. A schematic cross-sectional view of the gas-dissolved liquid generating apparatus according to Embodiment 3, one aspect of the present invention.

[0018] Embodiments of the present invention will be described below with reference to the drawings.

[0019] [Embodiment 1] The gas-dissolved liquid generating apparatus 1 of Embodiment 1, which is one aspect of the present invention as shown in Figure 1, comprises a pump 2, an ejector 3, a buffer tank 4, and a discharge line 5.

[0020] Pump 2 draws liquid from tank 6, which stores the liquid. The suction side of pump 2 communicates with the primary suction line 7 of pump 2, which is supplied with gaseous dissolved liquid from ejector 3. The discharge side of pump 2 communicates with a return line 8, which branches off from a supply line (not shown) that supplies the gaseous dissolved liquid to the utilization system of the gaseous dissolved liquid and returns a portion of the gaseous dissolved liquid to tank 6.

[0021] The ejector 3 is positioned between the tank 6 and the pump 2, and injects gas drawn from the buffer tank 4 into the flow of the liquid introduced from the tank 6 as the working fluid, thereby discharging the gas-dissolved liquid. For example, a well-known ejector described in Patent Documents 3, 4, etc., can be used as the ejector 3. The inlet 31 of the ejector 3 communicates with the inlet line 9 through which the liquid from the tank 6 is supplied. The gas suction 32 of the ejector 3 communicates with the gas suction line 10 through which gas introduced from the buffer tank 4 is supplied. The discharge 33 of the ejector 3 communicates with the primary side suction line 7 of the pump 2.

[0022] The buffer tank 4 is capable of storing the gas introduced by suction (reduced pressure supply) from an external gas supply system or the liquid that flows back from the gas suction section 32 of the ejector 3.

[0023] The gas supply system of this embodiment is designed to draw in gas at a pressure higher than the reduced pressure created by the suction force generated by the ejector 3, and includes gas supply systems under reduced pressure. Examples of such gas supply systems include gas supply systems below atmospheric pressure. More specifically, examples include well-known ozone gas supply systems that supply ozone gas with an ozone concentration of 50% by volume or more and an oxygen concentration of less than 50% by volume. In this case, the total pressure of the ozone gas becomes a reduced pressure state of, for example, 60 kPa (abs) or less (i.e., a state with an ozone partial pressure of 30 kPa (abs) or less).

[0024] A gas introduction line 11, through which the gas is supplied under reduced pressure from the gas supply system, is connected to the upper part of the buffer tank 4. The gas introduction line 11 is equipped with a flow control valve V1. A gas suction line 10, which communicates with the gas suction section 32 of the ejector 3, is connected to the side of the buffer tank 4 near the top. A discharge line 5 is connected to the bottom of the buffer tank 4.

[0025] The discharge line 5 discharges the liquid from the buffer tank 4 to the primary suction line 7 of the pump 2. The discharge line 5 is equipped with a flow control valve V2 that can appropriately discharge the liquid in the buffer tank 4 based on the liquid level of the buffer tank 4 detected by the liquid level sensor 12. The liquid level sensor 12 is not particularly limited and any well-known liquid level meter can be used as long as it can detect the liquid level in the buffer tank 4.

[0026] Referring to Figure 1, an example of the operation of the gas-dissolved liquid generator 1 of Embodiment 1 will be described. Here, the working fluid (liquid) is water, the gas is the ozone gas, and the gas-dissolved liquid is ozonated water. In particular, an example of stably supplying ozonated water with an ozone concentration of 200 ppm or higher will be described.

[0027] First, a predetermined amount of water is stored in the tank 6. Next, the pump 2 is started, and the water is circulated and supplied to the tank 6 via the inflow line 9, the ejector 3, the primary suction line 7, and the return line 8. After that, when the suction pressure of the ejector 3 reaches a pressure that can draw the ozone gas in the buffer tank 4 into the ejector 3, the ozone gas is supplied to the gas suction line 10 and the gas suction section 32 of the ejector 3, and is further injected into the water flowing through the orifice section of the ejector 3. The ozonated water discharged from the discharge section 33 of the ejector 3 is supplied to the pump 2 via the primary suction line 7. The ozonated water discharged from the pump 2 is returned to the tank 6 via the return line 8.

[0028] The ozonated water circulated to tank 6 is automatically supplied via a flow control valve V1, with the opening degree adjusted based on the ozone concentration and flow rate. Ozone gas is then injected from the ozone gas supply system into the water circulating in ejector 3 via the gas introduction line 11, buffer tank 4, and gas suction line 10. The ozonated water, with its ozone concentration adjusted to the desired level (for example, 200 mg / L or higher), is supplied to the ozonated water utilization system via the supply line branched from the return line 8. Water is then replenished to tank 6 from an external source as needed.

[0029] Here, if sufficient suction pressure cannot be obtained due to the supply water temperature or a malfunction of pump 2, and the pressure at the suction part of ejector 3 becomes equal to or higher than the gas supply pressure of gas suction line 10, the liquid will flow back into the buffer tank 4 via the gas suction part 32 and gas suction line 10. Next, when the liquid level in buffer tank 4 reaches the upper limit liquid level (the upper limit liquid level lower than the suction port of gas suction line 10), the flow control valve V2 opens. As a result, the fluid accumulated in buffer tank 4 is discharged to the primary side suction line 7 via the discharge line 5 by the suction force of pump 2. Then, when the liquid level in buffer tank 4 reaches the lower limit liquid level (the lower limit liquid level higher than the suction port of discharge line 5), the flow control valve V2 closes, and the discharge stops. This prevents backflow of water from the gas suction part 32 of ejector 3 to the gas suction line 10, buffer tank 4, and discharge line 5 due to the suction pressure of pump 2.

[0030] As described above, the gas-dissolved liquid generating apparatus 1 of this embodiment can prevent malfunctions and failures of the gas supply system that occur when sufficient suction pressure cannot be obtained due to abnormalities in the supply water temperature or circulation pump, etc., and the working fluid (liquid) flows back into the gas supply system and flows into gas flow meters, valves, etc. In particular, since the working fluid that flows back from the gas suction section 32 of the ejector 3 into the gas suction line 10 is discharged into the primary side suction line 7 of the pump 2, the amount of working fluid that blocks the airway of the gas suction line 10 can be minimized.

[0031] [Embodiment 2] In the gas-dissolved liquid generating apparatus 1 of Embodiment 2 of the present invention shown in Figure 2, a buffer tank 4 is positioned directly above the gas suction section 32 of a horizontally arranged ejector 3. A gas suction line 10, which is upright and communicates with the gas suction section 32 of the ejector 3, is drawn into the buffer tank 4 from the bottom of the buffer tank 4. In addition, a discharge line 5 is connected to the side surface near the bottom of the buffer tank 4. Except for the above configuration, this embodiment is the same as Embodiment 1.

[0032] As is clear from the above embodiments, the gas-dissolved liquid generating apparatus 1 of this embodiment provides the same effects as in Embodiment 1. In particular, the gas suction line 10 between the buffer tank 4 and the ejector 3 has a shorter flow path than the discharge line 5 between the buffer tank 4 and the primary side suction line 7, and the suction force of the ejector 3 is higher than the suction force of the pump 2. Therefore, even when the buffer tank 4 is empty and the flow control valve V2 of the discharge line 5 is open on the primary side suction line 7 of the pump 2, the balance between the suction pressure of the pump 2 and the suction pressure of the ejector 3 is less likely to be disrupted. Thus, the gas-dissolved liquid generated by injecting gas into a liquid can be supplied stably.

[0033] [Embodiment 3] The gas-dissolved liquid generating apparatus 1 of Embodiment 3, which is one aspect of the present invention shown in Figure 2, is the same as Embodiment 1 except that it is equipped with a buffer tank 4 that airtightly houses an ejector 3 which is arranged vertically or horizontally, instead of the buffer tank 4 of Embodiment 1.

[0034] The buffer tank 4 of this embodiment can be formed into any shape at the site where the gas-dissolved liquid generating device 1 is installed, and can store the gas supplied under reduced pressure from the gas supply system or the liquid that flows back from the gas suction section 32 of the ejector 3.

[0035] Furthermore, a gas introduction line 11 is connected to the top of the buffer tank 4 to introduce ozone gas supplied under reduced pressure from the ozone gas supply system. This gas introduction line 11 is equipped with a flow control valve V1. In addition, a discharge line 5 is connected to the bottom of the buffer tank 4 to discharge the liquid that has accumulated due to backflow from the gas suction section 32 of the ejector 3 and supply it to the primary suction line 7 of the pump 2. This discharge line 5 is equipped with a flow control valve V2 that can discharge the liquid in the buffer tank 4 as needed based on the liquid level of the buffer tank 4 detected by the liquid level sensor 12.

[0036] As is clear from the above embodiments, it is evident that the gas-dissolved liquid generating apparatus 1 of this embodiment provides the same effects as in Embodiment 1.

[0037] In other words, when generating ozonated water, which is a liquid containing dissolved gas, ozone gas is introduced by suction from the gas introduction line 11, supplied to the gas suction section 32 of the ejector 3 via the buffer tank 4, and injected into the water flowing through the orifice section of the ejector 3 to generate ozonated water. The ozonated water discharged from the discharge section 33 of the ejector 3 is supplied to the pump 2 via the primary suction line 7.

[0038] Here, if sufficient suction pressure cannot be obtained due to the supply water temperature or a malfunction of pump 2, the liquid that flows back from the gas suction section 32 of ejector 3 accumulates at the bottom of buffer tank 4. Next, when the liquid level in buffer tank 4 reaches the upper limit level (an upper limit level lower than the gas suction section 32 of ejector 3), the flow control valve V2 opens. As a result, the liquid accumulated in buffer tank 4 is discharged to the primary side suction line 7 via the discharge line 5 by the suction force of pump 2. Then, when the liquid level in buffer tank 4 reaches the lower limit level (a lower limit level higher than the suction port of discharge line 5), the flow control valve V2 closes, and the discharge stops. This prevents the liquid from flowing back from the gas suction section 32 of ejector 3 to buffer tank 4 and discharge line 5 due to the suction pressure of pump 2.

[0039] 1...Gas-dissolved liquid generation device 2...Pump 3...Ejector, 31...Inlet, 32...Gas suction, 33...Discharge 4...Buffer tank 5...Discharge line 6...Tank 7...Primary side suction line 8...Return line 9...Inlet line 10...Gas suction line 11...Gas introduction line 12...Liquid level sensor V1, V2...Flow control valves

Claims

1. A gas-dissolved liquid generating apparatus comprising: a pump for drawing in liquid; an ejector positioned on the primary side of the pump for injecting gas into the flow of liquid introduced by the suction to discharge a gas-dissolved liquid; a buffer tank capable of storing the gas introduced by suction or the liquid that flows back from the gas suction section of the ejector; and a discharge line for discharging the liquid from the buffer tank to the primary side suction line of the pump.

2. The gas-dissolved liquid generating apparatus according to claim 1, characterized in that the buffer tank is positioned directly above the horizontally positioned gas suction unit, an upright gas suction line communicating with the gas suction unit is drawn into the buffer tank from the bottom of the buffer tank, and the discharge line is connected to the side of the buffer tank near the bottom.

3. The gas-dissolved liquid generating apparatus according to claim 1 or 2, wherein the discharge line is equipped with a valve that discharges the liquid based on the liquid level of the liquid in the buffer tank, and the valve starts the discharge when the liquid level reaches an upper limit liquid level lower than the gas suction port in the buffer tank, and stops the discharge when the liquid level reaches a lower limit liquid level higher than the suction port of the discharge line in the buffer tank.

4. The gas-dissolved liquid generating apparatus according to claim 1, characterized in that the ejector is housed in the buffer tank.

5. The gas-dissolved liquid generating apparatus according to claim 4, wherein the discharge line is equipped with a valve for discharging the liquid based on the liquid level of the liquid in the buffer tank, and the valve starts discharging when the liquid level reaches an upper limit liquid level lower than the gas suction port, and stops discharging when the liquid level reaches a lower limit liquid level higher than the suction port of the discharge line in the buffer tank.

6. A method for producing a gas-dissolved liquid using a gas-dissolved liquid generating apparatus comprising: a pump for drawing in liquid; an ejector disposed on the primary side of the pump for injecting gas into the flow of liquid introduced by the suction to discharge a gas-dissolved liquid; and a buffer tank capable of storing the gas introduced by suction from an external source or the liquid that has backflowed from the gas suction section of the ejector, the method comprising: a process in which the liquid that has backflowed from the gas suction section is stored in the buffer tank; and a process in which the liquid is discharged from the buffer tank to the primary side suction line of the pump on the discharge side of the ejector.

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