Gas-dissolved liquid concentration control system

Abstract

To provide a gas-dissolved liquid concentration control system capable of shortening a time until a gas-dissolved liquid of a predetermined target concentration is generated, or capable of suppressing fluctuation of a concentration of the generated gas-dissolved liquid to be small.SOLUTION: A concentration of a gas-dissolved liquid measured by a concentration measurement unit 13 is input to a control unit 16 of a gas-dissolved liquid concentration control system 1, and the control unit 16 outputs a control input value to a raw material gas generation unit 6, thereby performing feedback control for controlling a gas amount of raw material gas generated by the raw material gas generation unit 6. In the feedback control, a control input value to be output to the raw material gas generation unit 6 is calculated based on a current value of a control input value input to the raw material gas generation unit 6, a current value of a concentration of the gas-dissolved liquid measured by the concentration measurement unit 13, a target concentration of the gas-dissolved liquid, and a correction value calculated in advance based on a relation between the control input value and the concentration of the gas-dissolved liquid measured during test run.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a gas solution concentration control system that controls the amount of source gas generated in a source gas generation unit so as to generate a gas solution having a predetermined target concentration. [Background technology]

[0002] Conventionally, there is known an ozone water generating device that automatically adjusts the concentration of ozone water to a target value (see, for example, Patent Document 1). In the conventional device, the concentration of ozone water is detected by a concentration meter, and if the detected concentration of ozone water is higher than a predetermined concentration target value, the voltage value of the ozone gas generator is lowered by one step, and if the detected concentration of ozone water is lower than the predetermined concentration target value, the voltage value of the ozone gas generator is raised by one step, thereby automatically adjusting the concentration of ozone water to the target value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-185572 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in conventional gas solution concentration control systems, if the detected ozone water concentration is higher than a predetermined concentration target value, the voltage value of the ozone gas generator is lowered by one step, and if the detected ozone water concentration is lower than a predetermined concentration target value, the voltage value of the ozone gas generator is raised by one step, thereby automatically adjusting the concentration of the ozone water to the target value.As a result, it takes a relatively long time for ozone water of the predetermined target concentration to be generated, and the concentration of the generated ozone water varies greatly (see Figure 5(b)).

[0005] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a gas dissolved liquid concentration control system that can shorten the time it takes for a gas dissolved liquid of a predetermined target concentration to be generated, or that can minimize fluctuations in the concentration of the gas dissolved liquid generated. [Means for solving the problem]

[0006] The gas solution concentration control system of the present invention comprises a raw material gas generation unit that generates a raw material gas, a gas dissolution unit that dissolves a raw material liquid in the raw material gas to generate a gas solution, a concentration measurement unit that measures the concentration of the gas solution generated by the gas dissolution unit and supplied to a point of use, and a control unit that controls the amount of the raw material gas generated by the raw material gas generation unit so that a gas solution of a predetermined target concentration is generated, wherein the control unit receives the concentration of the gas solution measured by the concentration measurement unit, and the control unit performs feedback control to control the amount of the raw material gas generated by the raw material gas generation unit by outputting a control input value to the raw material gas generation unit, and the feedback control calculates a control input value to be output to the raw material gas generation unit based on a current value of the control input value input to the raw material gas generation unit, a current value of the concentration of the gas solution measured by the concentration measurement unit, a target concentration of the gas solution, and a correction value that is calculated in advance based on the relationship between the control input value measured during a test run before starting production of the gas solution and the concentration of the gas solution.

[0007] According to this configuration, the amount of the raw gas generated in the raw gas generating unit is controlled so that a gas solution having a predetermined target concentration is generated. In this case, feedback control is performed to control the amount of the raw gas generated in the raw gas generating unit by outputting a control input value from the control unit to the raw gas generating unit. In this feedback control, the control input value output from the control unit to the raw gas generating unit is appropriately calculated based on the current value of the control input value, the current value of the concentration of the gas solution, the target concentration of the gas solution, and a correction value calculated in advance based on the relationship between the control input value measured during the test run and the concentration of the gas solution. Such feedback control can shorten the time until a gas solution having a predetermined target concentration is generated, or can suppress the fluctuation in the concentration of the generated gas solution to be small.

[0008] In addition, in the gas solution concentration control system of the present invention, the feedback control may calculate an initial value of the control input value to be output to the raw gas generation section based on the relationship between the control input value measured during the test run and the concentration of the gas solution.

[0009] According to this configuration, an initial value of the control input value to be output to the raw gas generating unit is calculated. Compared to the conventional case where the initial value is set empirically, an appropriate initial value is set, so that the time until a gas solution having a predetermined target concentration is generated can be shortened, or the fluctuation in the concentration of the generated gas solution can be suppressed to a small extent.

[0010] In addition, in the gas solution concentration control system of the present invention, a first control input value and a concentration of the first gas solution, and a second control input value and a concentration of the second gas solution are measured in the test run, and the initial value may be calculated by approximating the relationship between the first control input value and the concentration of the first gas solution, and the second control input value and the concentration of the second gas solution, with a linear function.

[0011] According to this configuration, by approximating the two measured values (the first control input value and the concentration of the first gas dissolved solution, and the second control input value and the concentration of the second gas dissolved solution) measured in the test run with a linear function, the initial value of the control input value to be output to the raw material gas generation unit can be appropriately calculated.

[0012] Further, in the gas dissolved solution concentration control system of the present invention, in the test run, the first control input value and the concentration of the first gas dissolved solution, the second control input value and the second gas dissolved solution, and the third control input value and the concentration of the third gas dissolved solution are measured, and the initial value may be calculated by approximating the relationship between the first control input value and the concentration of the first gas dissolved solution, the second control input value and the concentration of the second gas dissolved solution, and the third control input value and the third gas dissolved solution with a quadratic function.

[0013] According to this configuration, by approximating the three measured values (the first control input value and the concentration of the first gas dissolved solution, the second control input value and the concentration of the second gas dissolved solution, and the third control input value and the concentration of the third gas dissolved solution) measured in the test run with a quadratic function, the initial value of the control input value to be output to the raw material gas generation unit can be appropriately calculated.

[0014] Further, the gas dissolved solution concentration control system of the present invention includes a storage unit that stores the control input value input to the raw material gas generation unit as the previous value of the control input value when the generation of the gas dissolved solution is completed, and in the feedback control, the previous value of the control input value may be used as the initial value of the control input value to be output to the raw material gas generation unit when the generation of the gas dissolved solution is restarted.

[0015] According to this configuration, the control input value when the production of the gas solution is completed is stored as the previous control input value, and is used as the initial value of the control input value to be output to the raw gas production unit when the production of the gas solution is resumed. This allows an appropriate initial value to be set even when the control input value changes over time, so that it is possible to shorten the time until a gas solution with a predetermined target concentration is produced, or to minimize fluctuations in the concentration of the gas solution produced.

[0016] In addition, the gas solution concentration control system of the present invention may include a judgment unit that judges whether the control input value to be output to the raw gas generation unit is within a predetermined normal range, and a notification unit that issues an abnormality notification indicating an abnormality if the correction value is not within the normal range.

[0017] According to this configuration, when the control input value to be output to the raw material gas generating unit is not within a predetermined normal range, an abnormality notification is issued to indicate that an abnormality has occurred. This allows the user to recognize, for example, that a part has deteriorated over time (that it is time to replace the part).

[0018] The method of the present invention is a method executed by a control unit of a gas solution concentration control system, the gas solution concentration control system including a raw material gas generation unit that generates a raw material gas, a gas dissolving unit that dissolves the raw material gas in a raw material liquid to generate a gas solution, a concentration measuring unit that measures the concentration of the gas solution generated by the gas dissolving unit and supplied to a point-of-use, and the control unit that controls the amount of the raw material gas generated by the raw material gas generation unit so as to generate a gas solution having a predetermined target concentration, the method including the steps of: inputting the concentration of the gas solution measured by the concentration measuring unit; and performing feedback control to control the amount of the raw gas generated in the raw gas generation unit by outputting a control input value to the raw gas generation unit, wherein in the feedback control, a control input value to be output to the raw gas generation unit is calculated based on a current value of the control input value input to the raw gas generation unit, a current value of the concentration of the gas solution measured by the concentration measurement unit, a target concentration of the gas solution, and a correction value calculated in advance based on the relationship between the control input value measured during a test run before starting the generation of the gas solution and the concentration of the gas solution.

[0019] In this method, the amount of the raw gas generated in the raw gas generating unit is controlled so that a gas solution having a predetermined target concentration is generated, as in the above system. In this case, feedback control is performed to control the amount of the raw gas generated in the raw gas generating unit by outputting a control input value from the control unit to the raw gas generating unit. In this feedback control, the control input value output from the control unit to the raw gas generating unit is appropriately calculated based on the current value of the control input value, the current value of the concentration of the gas solution, the target concentration of the gas solution, and a correction value calculated in advance based on the relationship between the control input value measured during the test run and the concentration of the gas solution. Such feedback control can shorten the time until a gas solution having a predetermined target concentration is generated, or can suppress the fluctuation in the concentration of the generated gas solution to be small.

[0020] A program of the present invention is a program executed by a control unit of a gas solution concentration control system, the gas solution concentration control system including a raw material gas generation unit that generates a raw material gas, a gas dissolution unit that dissolves the raw material gas in a raw material liquid to generate a gas solution, a concentration measurement unit that measures a concentration of the gas solution generated by the gas dissolution unit and supplied to a point-of-use, and the control unit that controls the amount of the raw material gas generated by the raw material gas generation unit so as to generate a gas solution having a predetermined target concentration, the program including a process of inputting the concentration of the gas solution measured by the concentration measurement unit to the control unit. and a process of performing feedback control to control the amount of the raw gas generated in the raw gas generation unit by outputting a control input value to the raw gas generation unit. In the feedback control, a control input value to be output to the raw gas generation unit is calculated based on a current value of the control input value input to the raw gas generation unit, a current value of the concentration of the gas solution measured by the concentration measurement unit, a target concentration of the gas solution, and a correction value calculated in advance based on the relationship between the control input value measured during a test run before starting the generation of the gas solution and the concentration of the gas solution.

[0021] This program also controls the amount of raw gas generated in the raw gas generating unit so that a gas solution with a predetermined target concentration is generated, as in the above system. In this case, feedback control is performed to control the amount of raw gas generated in the raw gas generating unit by outputting a control input value from the control unit to the raw gas generating unit. In this feedback control, the control input value output from the control unit to the raw gas generating unit is appropriately calculated based on the current value of the control input value, the current value of the concentration of the gas solution, the target concentration of the gas solution, and a correction value calculated in advance based on the relationship between the control input value measured during the test run and the concentration of the gas solution. Such feedback control can shorten the time until a gas solution with a predetermined target concentration is generated, or can reduce the fluctuation in the concentration of the gas solution to be generated. Effect of the Invention

[0022] According to the present invention, it is possible to shorten the time until a gas solution having a predetermined target concentration is generated, or to minimize fluctuations in the concentration of the generated gas solution. [Brief description of the drawings]

[0023] [Figure 1] 1 is an explanatory diagram showing a configuration of an ozone water concentration control system according to an embodiment of the present invention. [Diagram 2] 1A is a diagram showing an example of measurement values ​​measured at two points in a test run, and FIG. 1B is a diagram showing an example of measurement values ​​measured at three points in a test run. [Diagram 3] FIG. 2 is a flow chart for explaining the operation (operation during a test run) of the ozone water concentration control system in the embodiment of the present invention. [Figure 4] FIG. 2 is a flow chart for explaining the operation (operation during generation of ozone water) of the ozone water concentration control system in the embodiment of the present invention. [Diagram 5] 1A is an explanatory diagram showing a change in the concentration of ozone water generated by an ozone water concentration control system according to an embodiment of the present invention, and FIG. 1B is an explanatory diagram showing a change in the concentration of ozone water generated by a conventional system. [Figure 6] FIG. 2 is an explanatory diagram showing another configuration of the ozone water concentration control system according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, a gas solution concentration control system according to an embodiment of the present invention will be described with reference to the drawings. In this embodiment, an ozone water concentration control system used in an ozone water generation system or the like will be described as an example. The ozone water concentration control system according to this embodiment has a function of shortening the time required to generate ozone water of a predetermined target concentration, or suppressing fluctuations in the concentration of the generated ozone water. These functions are realized by a program stored in a memory unit or the like of the ozone water concentration control system.

[0025] Figure 1 is an explanatory diagram showing the configuration of the ozone water concentration control system according to the present embodiment. As shown in Figure 1, the ozone water concentration control system 1 includes a gas supply line 2 to which oxygen serving as a raw material for ozone gas is supplied, and a liquid supply line 3 to which pure water (DIW) serving as a raw material for ozone water is supplied. The gas supply line 2 is provided with an on-off valve 4, a mass flow controller 5, and an ozone gas generation unit 6, and the ozone gas generation unit 6 generates a raw material gas (ozone gas) for ozone water. The liquid supply line 3 is provided with an on-off valve 7 and a booster pump 8. Here, the ozone gas generation unit 6 corresponds to the raw material gas generation unit of the present invention.

[0026] Then, the ozone gas generated by the ozone gas generation unit 6 and the pure water pressurized by the booster pump 8 are sent to the nozzle 9, and ozone water is generated. The ozone water generated at the nozzle 9 is sent to the gas-liquid separator 10 and separated into ozone water supplied to the use point and exhaust gas discharged from the exhaust port. Here, the nozzle 9 corresponds to the gas dissolution unit of the present invention.

[0027] The gas-liquid separator 10 is provided with a liquid delivery line 11 through which ozone water supplied to the use point is delivered, and an exhaust line 12 through which exhaust gas discharged from the exhaust port is delivered. The liquid delivery line 11 is provided with a concentration meter 13 for measuring the concentration of the ozone water supplied to the use point. Further, the exhaust line 12 is provided with a decomposition catalyst 14 for decomposing the exhaust gas and a pressure regulating valve 15 for adjusting the pressure of the exhaust gas from the exhaust port. Here, the concentration meter 13 corresponds to the concentration measurement unit of the present invention.

[0028] Furthermore, the ozone water concentration control system 1 of this embodiment includes a control unit 16 that controls the amount of raw material gas generated in the ozone gas generation unit 6 so that ozone water of a predetermined target concentration is generated. The concentration of ozone water measured by the concentration meter 13 is input to this control unit 16, and the control unit 16 performs feedback control to control the amount of raw material gas generated in the ozone gas generation unit 6 by outputting a control input value to the ozone gas generation unit 6. Note that, although a BCD value (Binary-Coded Decimal value) is used as the control input value here, other values ​​such as a current value can also be used.

[0029] In this feedback control, a control input value to be output to the ozone gas generating unit 6 is calculated based on the current value of the control input value input to the ozone gas generating unit 6, the current value of the concentration of ozone water measured by the concentration meter 13, the target concentration of ozone water, and a correction value calculated in advance based on the relationship between the control input value and the concentration of ozone water measured during a test run before the start of ozone water generation. In this embodiment, the control input value to be output to the ozone gas generating unit 6 is calculated based on the following formula. Control input value = control input value (current value) + (target density - current density) x correction value

[0030] In addition, in this feedback control, an initial value of the control input value to be output to the ozone gas generating unit 6 is calculated based on the relationship between the control input value and the concentration of ozone water measured during the test run. For example, as shown in Fig. 2(a), when two measured values ​​(a first control input value and the concentration of the first ozone water, and a second control input value and the concentration of the second ozone water) are measured during the test run, the initial value is calculated by approximating the relationship between the first control input value and the concentration of the first ozone water, and the second control input value and the concentration of the second ozone water, using a linear function.

[0031] In the example of FIG. 2(a), the first control input value is 2000, the first ozone water concentration is 15 mg / L, the second control input value is 3000, and the second ozone water concentration is 25 mg / L. In this case, if the control input value is X and the ozone water concentration is Y, it can be approximated to a linear function of Y=BX+C, and B=0.01 and C=-5 are obtained. At this time, the correction value is obtained from the slope B of the two points and calculated as 1 / B=100. In addition, if the target ozone water concentration is 20, the initial value of the control input value is obtained from the approximated linear equation and calculated as X=(YC) / B=2500.

[0032] In this case, when the generation of ozone water is started, the initial value 2500 calculated as described above is used first. Thereafter, feedback control is performed at every predetermined elapsed time (times T1, T2, ...) (see FIG. 5(a)). For example, at time T1, the initial value 2500 is used as the current value of the control input value, and if the concentration of ozone water measured by concentration meter 13 at this time is 22 mg / L, the control input value to be output to ozone gas generator 6 at time T1 is calculated as 2300 (=2500+(20-22)×100) based on the above formula.

[0033] At the next time T2, the above 2300 is used as the current value of the control input value, and if the concentration of ozone water measured by the concentration meter 13 at this time is 19 mg / L, then based on the above formula, the control input value to be output to the ozone gas generator 6 at time T2 is calculated as 2400 (=2300+(20-19)×100). Thereafter, feedback control is repeated until the generation of ozone water is completed.

[0034] Furthermore, for example, as shown in FIG. 2(b), when three measurement values ​​(first control input value and first ozone water concentration, second control input value and second ozone water concentration, and third control input value and third ozone water concentration) are measured in a test run, an initial value is calculated by approximating the relationship between the first control input value and first ozone water concentration, the second control input value and second ozone water concentration, and the third control input value and third ozone water with a quadratic function.

[0035] In the example of Fig. 2(b), the first control input value is 1500, the concentration of the first ozone water is 10 mg / L, the second control input value is 2000, the concentration of the second ozone water is 19 mg / L, the third control input value is 3000, and the concentration of the third ozone water is 25 mg / L. In this case, if the control input value is X and the concentration of the ozone water is Y, then Y = AX 2 can be approximated by a quadratic function of + BX + C, and A = -0.000008, B = 0.046, and C = -41 are obtained. At this time, the correction value is calculated as 1 / α = 56 from the slope α of the two smaller values among the three points (ozone water concentrations 10 and 19 mg / L), and 1 / β = 166 is calculated from the slope β of the two larger values among the three points (ozone water concentrations 19 and 25 mg / L). In feedback control, among these two correction values 1 / α and 1 / β, the correction value of the closer ozone water concentration value is used. That is, within the range of the ozone water concentration from 10 to 19 mg / L, the correction value 1 / α is used, and within the range of the ozone water concentration from 19 to 25 mg / L, the correction value 1 / β is used. Also, when the target ozone water concentration is 20, the initial value of the control input value is obtained from the approximated quadratic formula, and X = (-B ± (B 2 - 4AC) 0.5 ) / 2A = 2075, 3675 (among these, X = 2075 within the test run range) is calculated.

[0036] In this case, when starting the generation of ozone water, first, the initial value 2075 calculated as described above is used. Thereafter, feedback control is performed at every predetermined elapsed time (times T1, T2,...) (see Fig. 5(a)). For example, at time T1, the initial value 2075 is used as the current value of the control input value. Assuming that the concentration of the ozone water measured by the concentration meter 13 at this time is 22 mg / L, then using the correction value 1 / β = 166 calculated from the slope β of the two larger values among the three points (ozone water concentrations 19 and 25 mg / L), the control input value to be output to the ozone gas generation unit 6 at time T1 is calculated as 1743 (= 2075 + (20 - 22) × 166).

[0037] At the next time T2, the above 1743 is used as the current value of the control input value, and if the concentration of ozone water measured by the concentration meter 13 at this time is 19 mg / L, the control input value to be output to the ozone gas generator 6 at time T2 is calculated as 1799 (=1743+(20-19)×56) using a correction value 1 / α=56 calculated from the slope α of the two smallest values ​​of the three points (ozone water concentrations 10 and 19 mg / L). Thereafter, feedback control is repeated until the generation of ozone water is completed.

[0038] Moreover, the ozone water concentration control system 1 of this embodiment includes a storage unit 17 that stores the control input value input to the ozone gas generator 6 as the previous control input value when the generation of ozone water is terminated. In the feedback control, the previous control input value can be used as the initial value of the control input value to be output to the ozone gas generator 6 when the generation of ozone water is resumed.

[0039] Furthermore, the ozone water concentration control system 1 of this embodiment includes a determination unit 18 that determines whether or not the control input value to be output to the ozone gas generation unit 6 is within a predetermined normal range, and a notification unit 19 that issues an abnormality notification indicating that an abnormality exists when the correction value is not within the normal range. For example, when the control input value to be output to the ozone gas generation unit 6 becomes 3500 or more, an abnormality notification is issued indicating that an abnormality exists.

[0040] The operation of the ozone water concentration control system 1 configured as above will be described with reference to the flow charts of FIG. 3 and FIG.

[0041] When ozone water is generated using the ozone water concentration control system 1 according to the embodiment of the present invention, a test run is first started (S1) as shown in FIG. 3, and a control input value and the concentration of ozone water are measured in advance (S2). For example, two measurement points are measured in advance as shown in FIG. 2(a). Alternatively, three measurement points are measured in advance as shown in FIG. 2(b). Then, an initial value and a correction value of the control input value are calculated based on the results of the advance measurement (S3). For example, an initial value is calculated by approximating the results of the two measurement points with a linear function, and a correction value is calculated from the slope of the two points. Alternatively, an initial value is calculated by approximating the results of the three measurement points with a quadratic function, and two correction values ​​are calculated from the slopes of two of the three points.

[0042] 4, when ozone water is generated (S10), first, it is determined whether or not the control input value input to the ozone gas generating unit 6 when the previous generation of ozone water was completed is stored as a previous value (S11), and if the previous value is stored, the previous value is used as the initial value of the control input value (S12). On the other hand, if the previous value is not stored, a calculated initial value is used as the initial value of the control input value (S13).

[0043] Then, when feedback control is started (S14), the concentration of ozone water is measured at every predetermined time (time T1, T2, ...), and a control input value to be output to the ozone gas generating unit 6 is calculated (S16). Next, it is determined whether the calculated control input value is within a normal range (S17), and if it is determined that it is not within the normal range, an abnormality notification is issued (S18). On the other hand, if it is determined that it is within the normal range, it is output as a control input value to the ozone gas generating unit 6 (S19).

[0044] The above processes (S15 to S19) are repeated until the generation of ozone gas is completed. Then, when the generation of ozone gas is completed (S20), the control input value output to the ozone gas generator 6 at that time is stored as the previous value (S21).

[0045] According to the ozone water concentration control system 1 of the present embodiment, the amount of the raw material gas generated in the ozone gas generating unit 6 is controlled so that ozone water of a predetermined target concentration is generated. In this case, feedback control is performed to control the amount of the raw material gas generated in the ozone gas generating unit 6 by outputting a control input value from the control unit 16 to the ozone gas generating unit 6. In this feedback control, the control input value output from the control unit 16 to the ozone gas generating unit 6 is appropriately calculated based on the current value of the control input value, the current value of the concentration of the ozone water, the target concentration of the ozone water, and a correction value calculated in advance based on the relationship between the control input value measured during the test run and the concentration of the ozone water. By such feedback control, as shown in FIG. 5(a), it is possible to shorten the time until ozone water of a predetermined target concentration is generated, or to suppress the fluctuation in the concentration of the generated ozone water to a small value.

[0046] In this embodiment, an initial value is calculated for the control input value to be output to the ozone gas generator 6. An appropriate initial value is set even for changes over time in the control input value, so that it is possible to shorten the time required for ozone water of a predetermined target concentration to be generated, or to minimize fluctuations in the concentration of the generated ozone water.

[0047] Furthermore, in this embodiment, as shown in FIG. 2(a), the initial value of the control input value to be output to the ozone gas generation unit 6 can be appropriately calculated by approximating two measurement values ​​(the first control input value and the first ozone water concentration, and the second control input value and the second ozone water concentration) measured in a test run with a linear function.

[0048] Alternatively, in this embodiment, as shown in Figure 2(b), the initial value of the control input value to be output to the ozone gas generation unit 6 can be appropriately calculated by approximating three measurement values ​​measured in a test run (the first control input value and the first ozone water concentration, the second control input value and the second ozone water concentration, and the third control input value and the third ozone water concentration) with a quadratic function.

[0049] Furthermore, in this embodiment, the control input value when the generation of ozone water is terminated is stored as the previous control input value, and is used as the initial value of the control input value to be output to the ozone gas generator 6 when the generation of ozone water is resumed. This allows a more appropriate initial value to be set compared to the conventional case in which the initial value is set empirically, so that it is possible to shorten the time until ozone water of a predetermined target concentration is generated, or to minimize fluctuations in the concentration of the generated ozone water.

[0050] In this embodiment, when the control input value to be output to the ozone gas generating unit 6 is not within a predetermined normal range, an abnormality notification is issued to indicate that an abnormality has occurred. This allows the user to recognize, for example, that a part has deteriorated over time (that it is time to replace the part).

[0051] Although the embodiments of the present invention have been described above by way of example, the scope of the present invention is not limited to these, and changes and modifications can be made according to the purpose within the scope of the claims.

[0052] For example, in the above description, the gas-dissolved liquid is ozone water, but other gas-dissolved liquids can be used in the same manner. In addition, in the above embodiment, the system for generating ozone water using a nozzle 9 and a gas-liquid separator 10 as shown in Fig. 1 is described, but the system for generating ozone water using a dissolution film 20 as shown in Fig. 6 can be used in the same manner. [Industrial Applicability]

[0053] As described above, the gas dissolved liquid concentration control system of the present invention has the effect of being able to shorten the time required for a gas dissolved liquid of a predetermined target concentration to be generated, or of being able to minimize fluctuations in the concentration of the gas dissolved liquid generated, and is useful, for example, in ozone water generation systems, etc. [Explanation of symbols]

[0054] 1. Ozone water concentration control system (gas dissolved liquid concentration control system) 2 Gas supply lines 3 Liquid Supply Lines 4 Opening and closing valve 5 Mass Flow Controller 6 Ozone gas generator (raw gas generator) 7 Opening and closing valve 8 Booster Pump 9 Nozzle (gas dissolving part) 10 Gas-liquid separator 11 Liquid delivery line 12 Exhaust line 13 Densitometer (concentration measuring section) 14 Decomposition catalyst 15 Pressure Regulating Valve 16 Control section 17 Memory section 18 Judgment section 19 Notification Department 20 Dissolved membrane (gas dissolving part)

Claims

1. a raw material gas generating unit that generates a raw material gas; a gas dissolution unit that dissolves the source gas in a source liquid to generate a gas solution; a concentration measuring unit for measuring the concentration of the gas solution generated in the gas dissolving unit and supplied to a point of use; a control unit that controls the amount of the source gas generated in the source gas generating unit so that a gas solution having a predetermined target concentration is generated; Equipped with The control unit receives an input of the concentration of the gas solution measured by the concentration measurement unit, the control unit performs feedback control to control the amount of the raw material gas generated by the raw material gas generation unit by outputting a control input value to the raw material gas generation unit; In the feedback control, a control input value to be output to the raw gas generation unit is calculated based on a current value of a control input value input to the raw gas generation unit, a current value of the concentration of the gas solution measured by the concentration measurement unit, a target concentration of the gas solution, and a correction value calculated in advance based on the relationship between the control input value and the concentration of the gas solution measured during a test run before starting generation of the gas solution.

2. In the feedback control, 2. The gas dissolved liquid concentration control system according to claim 1, wherein an initial value of the control input value to be output to the raw gas generation unit is calculated based on the relationship between the control input value measured during the test run and the concentration of the gas dissolved liquid.

3. In the test run, a first control input value and a concentration of a first dissolved gas, and a second control input value and a concentration of a second dissolved gas are measured; 3. The gas dissolved liquid concentration control system of claim 2, wherein the initial value is calculated by approximating a relationship between a first control input value and a concentration of the first gas dissolved liquid and a second control input value and a concentration of the second gas dissolved liquid with a linear function.

4. In the test run, a first control input value and a concentration of a first dissolved gas, a second control input value and a concentration of a second dissolved gas, and a third control input value and a concentration of a third dissolved gas are measured; 3. The gas dissolved liquid concentration control system of claim 2, wherein the initial value is calculated by approximating a relationship between a first control input value and a concentration of the first gas dissolved liquid, a second control input value and a concentration of the second gas dissolved liquid, and a third control input value and a concentration of the third gas dissolved liquid, using a quadratic function.

5. a storage unit that stores a control input value that has been input to the raw material gas generation unit as a previous value of the control input value when the generation of the gas solution is completed, In the feedback control, 2. The gas dissolved liquid concentration control system according to claim 1, wherein when production of the gas dissolved liquid is resumed, a previous value of the control input value is used as an initial value of the control input value to be output to the raw gas production section.

6. a determination unit that determines whether a control input value to be output to the raw material gas generation unit is within a predetermined normal range; a notification unit that issues an abnormality notification indicating that the correction value is abnormal if the correction value is not within the normal range; The gas dissolved liquid concentration control system according to claim 1 , comprising:

7. A method executed by a control unit of a gas solution concentration control system, comprising: The gas solution concentration control system includes: a raw material gas generating unit that generates a raw material gas; a gas dissolution unit that dissolves the source gas in a source liquid to generate a gas solution; a concentration measuring unit for measuring the concentration of the gas solution generated in the gas dissolving unit and supplied to a point of use; the control unit controls the amount of the source gas generated in the source gas generation unit so that a gas solution having a predetermined target concentration is generated; Equipped with The method comprises: A step of inputting the concentration of the gas solution measured by the concentration measuring unit; performing feedback control to control the amount of the raw material gas generated in the raw material gas generating unit by outputting a control input value to the raw material gas generating unit; Including, In the feedback control, a control input value to be output to the raw gas generation unit is calculated based on a current value of a control input value input to the raw gas generation unit, a current value of the concentration of the gas dissolved liquid measured by the concentration measurement unit, a target concentration of the gas dissolved liquid, and a correction value calculated in advance based on the relationship between the control input value measured during a test run before starting generation of the gas dissolved liquid and the concentration of the gas dissolved liquid.

8. A program executed by a control unit of the gas solution concentration control system, The gas solution concentration control system includes: a raw material gas generating unit that generates a raw material gas; a gas dissolution unit that dissolves the source gas in a source liquid to generate a gas solution; a concentration measuring unit for measuring the concentration of the gas solution generated in the gas dissolving unit and supplied to a point of use; the control unit controls the amount of the source gas generated in the source gas generation unit so that a gas solution having a predetermined target concentration is generated; Equipped with The program causes the control unit to A process of inputting the concentration of the gas solution measured by the concentration measurement unit; a process of performing feedback control to control the amount of the raw material gas generated by the raw material gas generating unit by outputting a control input value to the raw material gas generating unit; The above is executed. In the feedback control, a control input value to be output to the raw gas generation unit based on a current value of a control input value input to the raw gas generation unit, a current value of the concentration of the gas solution measured by the concentration measurement unit, a target concentration of the gas solution, and a correction value calculated in advance based on the relationship between the control input value and the concentration of the gas solution measured during a test run before starting generation of the gas solution, said program.

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