JP6565347B2 - Method for producing gas-dissolved water - Google Patents

Description

  The present invention relates to a method and an apparatus for producing gas-dissolved water, and more particularly, to a method and apparatus for safely producing gas-dissolved water having a high liquid temperature and a high dissolved gas concentration and supplying it to a place of use.

  Hydrogen gas-dissolved water and nitrogen gas-dissolved water are used as cleaning liquids for electronic materials, etc., and in order to increase the cleaning power, the dissolved gas concentration of the gas-dissolved water is increased and the liquid temperature is increased. It has been broken.

  However, when the liquid temperature becomes high, the dissolved gas concentration of the gas-dissolved water exceeds the saturation solubility, and there is a possibility of foaming. For example, Patent Document 1 discloses that ozone gas-dissolved water foams and the cleaning effect is reduced due to uneven cleaning due to bubbles adhering to the surface of the object to be cleaned; It is described that the problem that the vibrator is damaged due to the vibration of the vibrator is caused. In addition, when bubbles remain in the liquid feeding pipe, there is a problem that it is difficult to completely extrude the bubbles.

Conventionally, as a countermeasure for preventing foaming when using high-temperature gas-dissolved water, it has been proposed to pressurize the gas-dissolved water or use it after removing a part of the dissolved gas.
For example, Patent Documents 2 and 3 describe that the temperature of gas-dissolved water is in the range of 10 to 90 ° C., and also describes that pressurization is performed to increase the solubility of gas-dissolved water.
In Patent Document 4, in order to stably adjust gas-dissolved water having a temperature of about 40 to 50 ° C., a part of the dissolved gas is removed by depressurizing high-concentration gas-dissolved water prepared to have a solubility or higher. Is described.

JP 2017-93357 A JP 2011-134864 A JP 2012-143708 A JP 2007-243113 A

However, in order to put the inside of the washing machine into a pressurized state so that the gas-dissolved water used at the time of washing does not foam, the equipment for that is complicated.
Further, the method for removing dissolved gas has a problem of exhaust gas treatment because the removed gas is released out of the system. For example, for explosive hydrogen gas, it is a preferable method from the viewpoint of safety. It can not be said.
In order to surely prevent foaming, setting the dissolved gas concentration to a low value cannot cope with a case where a high cleaning power is required because the cleaning power of the dissolved gas decreases.

  For this reason, it is desired to produce gas-dissolved water having a dissolved gas concentration that is as close as possible to the saturation solubility without exceeding the saturation solubility at the liquid temperature of the heated gas-dissolved water.

  It is an object of the present invention to provide a method and an apparatus for safely producing a gas dissolved water having a high liquid temperature and a high dissolved gas concentration and supplying it to a place of use.

As a result of repeated studies to solve the above problems, the present inventors have measured the liquid temperature of heated gas-dissolved water, and controlled the amount of gas dissolved in the gas-dissolved water based on this measured value. It has been found that gas-dissolved water having a dissolved gas concentration close to the saturation solubility can be produced without exceeding the saturation solubility.
That is, the gist of the present invention is as follows.

[1] A gas dissolving step of dissolving a dissolved gas composed of a gas that does not self-decompose in water in the supply water, and a heating step of heating the obtained gas-dissolved water to a target value T ₀ of the liquid temperature. In the method for producing gas dissolved water, the dissolved gas concentration of the gas dissolved water does not exceed the saturation solubility in the measured value T based on the measured value T of the liquid temperature of the gas dissolved water after heating in the heating step. Thus, the method for producing gas-dissolved water, wherein the amount of gas dissolved in the gas-dissolving step is controlled.

[2] In [1], when the measurement value T is less than the target value T ₀ , the gas dissolution amount is controlled by any one of the following (1) to (4), and the measurement is performed. After the value T reaches the target value T ₀ , the gas dissolution amount is controlled by any one of the following (2) to (4).
(1) The gas dissolution amount of the gas dissolved water is controlled using the saturation solubility of the gas to be dissolved at the target value T ₀ obtained in advance as the adjustment value of the dissolved gas concentration.
(2) A continuous calibration relationship between the liquid temperature of the gas-dissolved water and the saturated solubility of the gas to be dissolved is obtained in advance, and the saturated solubility at the measured value T obtained from the calibration relationship is calculated as the dissolved gas concentration. The gas dissolution amount of the gas dissolution water is controlled as an adjustment value.
(3) A calibration relationship between the liquid temperature of the gas-dissolved water and the saturated solubility of the gas to be dissolved is obtained in advance at a predetermined liquid temperature interval, and the measured value T of the liquid temperatures indicated in the calibration relationship is obtained. And the amount of dissolved gas in the gas dissolved water is controlled using the saturation solubility at the liquid temperature closest to the measured value T as the adjusted value of the dissolved gas concentration.
(4) A calibration relationship between the liquid temperature of the gas-dissolved water and the saturated solubility of the gas to be dissolved is obtained in advance at a predetermined liquid temperature interval, and the measured value T reaches the liquid temperature indicated by the calibration relationship. In some cases, the amount of gas dissolved in the gas dissolved water is controlled using the saturation solubility at the liquid temperature as an adjustment value of the dissolved gas concentration.

[3] In [2], the calibration relationship obtained at the predetermined liquid temperature interval is a relationship between the liquid temperature and the saturation solubility at the liquid temperature at a liquid temperature interval of 10 ° C. or less. To produce gas-dissolved water.

[4] The gas according to any one of [1] to [3], wherein the temperature of the feed water is 20 ° C. or higher, and the rising temperature of the dissolved gas due to the heating is 10 ° C. or higher. A method for producing dissolved water.

[5] The gas-dissolved water according to any one of [1] to [4], wherein the target value T ₀ is less than 80 ° C., and a saturated solubility ratio calculated by the following formula is 70% or more. Manufacturing method.
Saturation solubility ratio = (S _X / S) × 100
(In the above formula, S represents the saturation solubility at the measured value T, and S _X represents the dissolved gas concentration of the gas-dissolved water.)

[6] The method for producing gas-dissolved water according to [5], wherein the target value T ₀ is less than 70 ° C., and the saturation solubility ratio is 80% or more.

[7] The method for producing gas-dissolved water according to any one of [1] to [6], wherein the heating intensity of the gas-dissolved water is controlled based on the measured value T.

[8] In [7], an inflow amount of the gas-dissolved water into the heating step is measured, and the gas-dissolved water is measured based on a measured value of the inflow amount of the gas-dissolved water and the measured value T. A method for producing gas-dissolved water, wherein the heating intensity is controlled.

[9] Gas dissolving means for dissolving a gas to be dissolved made of a gas that does not self-decompose in water in supply water, and heating means for heating the obtained gas dissolved water so as to reach a target value T ₀ of the liquid temperature. In the gas dissolved water production apparatus, the liquid temperature measuring means for measuring the liquid temperature of the gas dissolved water after heating in the heating means, and the dissolved gas of the gas dissolved water based on the measured value T of the liquid temperature And a control means for controlling the amount of dissolved gas in the gas dissolving means so that the concentration does not exceed the saturation solubility at the measured value T.

  According to the present invention, based on the measured value of the liquid temperature of the heated gas-dissolved water, the manufactured heated gas is used to control the amount of gas-dissolved water dissolved so as not to exceed the saturation solubility at the liquid temperature. The dissolved water does not exceed the saturation solubility and the risk of foaming can be avoided. Moreover, it can be set as the dissolved gas density | concentration close | similar to saturation solubility, and dissolved gas density | concentration is high enough, and heated gas dissolved water with a high cleaning effect can be supplied to a use place.

  In the present invention, the produced gas-dissolved water can be supplied to the place of use without increasing the saturation solubility by pressurization or cooling after heating. Therefore, it is possible to use gas-dissolved water that maintains a high dissolved gas concentration. it can. In addition, since there is no generation or discharge of surplus gas from gas dissolution to supply to the place of use, exhaust gas treatment becomes unnecessary, and when explosive gas such as hydrogen gas is used as dissolved gas, it is safe Can be processed.

It is a systematic diagram which shows embodiment of the manufacturing apparatus of the gas dissolution water of this invention. It is a graph which shows the relationship between the temperature rising time by a heater, and heater exit temperature.

  Hereinafter, embodiments of the present invention will be described in detail.

[mechanism]
When manufacturing heated gas-dissolved water, the target value T ₀ of the gas-dissolved water heating temperature is set as the required cleaning liquid temperature from the use point (use point) where the heated gas-dissolved water is used as the cleaning liquid. is the measured value T of the liquid temperature after heating of the gas dissolved water is, so as to approach the target value T _0, the heater heating intensity can be determined from prior heating of the gas dissolved water temperature and flow rate.

However, only by adjusting the heating intensity of the heater may is not easy to control the target value T _0, the heater outlet temperature T, i.e., the measured value T of the liquid temperature of the gas dissolved water after heating varies Sometimes. For example, as the heating intensity increases from the start of operation of the heater, the heater outlet temperature, that is, the measured value T of the liquid temperature, gradually increases, and the outlet temperature (measured value T) reaches the target value T ₀ (hereinafter, this target). The stage until the value T ₀ is reached may be referred to as “stage 1”). From this point, the fine adjustment of the heater heating intensity, after the measurement value T has reached the stable to (the target value T ₀ after a while varied target value T ₀ near the measured value T of the phase to stabilize The stage where the measured value T is stabilized after that is referred to as “stage 2”, and may be referred to as “stage 3”. However, strictly speaking, even in the stage 3, since there is a slight flow rate fluctuation in the feed water (raw water), the heater outlet temperature thereafter fluctuates slightly.

For example, gas dissolved water in which about 36 mg / L of oxygen gas is dissolved is supplied to a heater “DI WATER HEATER, HDWII-12N” manufactured by Omega Semicon Electronics Co., Ltd. at a flow rate of 5.8 L / min. When a heating experiment was performed by setting the value T ₀ to 66 ° C. and heating, the amount of water flowing into the heater also fluctuated due to fluctuations in the flow rate from the raw water supply side, and the temperature rise time and the heater outlet temperature (gas after heating) corresponds to the measured value of the liquid temperature of the dissolution water.) relationship between becomes as shown in Table 1 and Figure 2, the heater outlet temperature after reaching the target value T ₀ may vary slightly.

In the conventional method, as shown in Comparative Example 1 described later, since the saturated solubility at the target value T ₀ is set as the adjustment value of the dissolved gas concentration of the gas dissolved water to produce the gas dissolved water, the target value T ₀ After reaching the value, the saturation solubility may be exceeded due to fluctuations in the actual heating temperature, and foaming may occur.

In the present invention, the liquid temperature of the heated gas dissolved water is measured, so that the dissolved gas concentration of the gas dissolved water does not exceed saturation solubility in the measured value T even after the measurement value T has reached the target value T ₀ Such foaming problems are avoided because the amount of dissolved gas is controlled.
Moreover, by controlling the dissolved gas concentration close to the saturation solubility at the liquid temperature based on the measured value T of the liquid temperature, it is possible to produce gas dissolved water having a high dissolved gas concentration.

[Dissolved gas]
In the present invention, since the gas-dissolved water is heated, ozone gas that self-decomposes by heating cannot be applied as the gas to be dissolved. Examples of the gas to be dissolved that does not self-decompose in water include noble gases such as hydrogen gas, oxygen gas, nitrogen gas, and argon gas, but are not limited thereto.

[Supply water]
As the supply water for dissolving the gas to be dissolved, ultrapure water is usually used.
In particular, when the produced gas-dissolved water is used as a cleaning liquid for electronic materials, the ultrapure water used as the supply water has an electrical resistivity at a temperature of 25 ° C. of 18 MΩ · cm or more and an organic carbon concentration of 10 μg / L or less. The metal content is preferably 20 ng / L or less, and the fine particle content is preferably 10,000 particles / L or less.

  In addition, when using ultrapure water, it may be purged with nitrogen after deaeration and used as an aqueous solution with a water quality equivalent to nitrogen gas-dissolved water. Especially when used as warm ultrapure water, it is purged so that purge nitrogen does not foam. Since it is preferable to control the amount, ultrapure water purged with nitrogen gas is also included in the nitrogen gas-dissolved water in the present invention.

[Dissolution and heating of dissolved gas]
Dissolution of the gas to be dissolved in the feed water can be performed according to a conventional method.

  For example, after the supply water is deaerated in the deaeration membrane module as necessary, the supplied water is supplied to the gas phase chamber of the gas permeable membrane module in which the gas phase chamber and the liquid phase chamber are partitioned through the gas permeable membrane. There is a method of dissolving a gas to be dissolved using a gas dissolving membrane module in which dissolved gas is transferred to supply water supplied to a liquid phase chamber via a gas permeable membrane and dissolved.

  Further, the dissolved gas can be dissolved by bubbling an excessive amount of the dissolved gas into the degassed supply water under normal pressure.

Gas-dissolved water can also be heated using a heater according to a conventional method. However, in order to avoid deterioration of the quality of the gas-dissolved water due to the heat treatment, the liquid contact member of the heating means is deteriorated in water quality such as fluororesin. It is preferable to use a member that does not have a risk of incurring.
For example, heat having a structure in which a plurality of tubes made of fluororesin are bundled and put in a container, gas dissolved water is allowed to flow inside or outside the tube, and the heating medium is passed or held on the opposite side through the tube wall surface. An exchanger can be used. In this case, the heating intensity can be adjusted by adjusting the temperature and flow rate of the heating medium.
Alternatively, it is also possible to use a heater that is heated by a radiant heater such as a halogen lamp installed in a space outside the water pipe while passing the gas-dissolved water through the light-transmitting quartz water pipe. In this case, the heating intensity can be adjusted by adjusting the output of the radiant heating element.

  The material of the water supply pipe for feeding the supply water and the gas-dissolved water is not limited as long as it does not deteriorate the water quality, and a material such as CVP (vinyl chloride) or PVDF (polyvinylidene fluoride) having low gas permeability is desirable. However, this is not the case when a high deaeration level (for example, a dissolved oxygen gas concentration of 50 ppb or less) is not required.

[Control of dissolved gas amount]
In the present invention, the temperature of the gas-dissolved water after heating is measured, and based on this measured value T, the dissolved gas concentration of the gas-dissolved water is dissolved in the supply water so as not to exceed the saturation solubility at the measured value T. Controls the amount of gas to be dissolved.

  Specifically, a calibration relationship between the liquid temperature of the gas-dissolved water and the saturated solubility of the gas to be dissolved at the liquid temperature is obtained in advance, and the saturated solubility corresponding to the measured value T is obtained from the calibration relationship, and the gas-dissolved water is obtained. There is a method of controlling the gas dissolution amount of the gas dissolved water so that the dissolved gas concentration of the gas is equal to or lower than the saturation solubility.

  This gas dissolution amount control is performed by, for example, transmitting a temperature signal of a liquid temperature measured by a thermometer provided in a heater or a heating pipe for supplying heated gas dissolved water from the heater to the control means, and preparing the control means in advance. Based on the calibration relationship, it is preferable to automatically adjust the output of the gas dissolving means so as to achieve the desired dissolved gas concentration.

  For example, when the gas to be dissolved is pressurized and supplied to the gas phase chamber of the gas dissolution membrane module with respect to the degassed supply water, and dissolved in the supply water in the liquid phase chamber The amount of dissolved gas can be adjusted by adjusting the output of a pump that pressurizes and supplies the gas to be dissolved. Alternatively, if the dissolved gas is dissolved by bubbling an excessive amount of the dissolved gas into the degassed feed water under normal pressure, the gas dissolved amount can be adjusted by adjusting the output of the aeration blower. Can do.

The control of the gas dissolution amount may always be performed based on the liquid temperature measurement value T based on the saturation solubility at the liquid temperature, and when the liquid temperature measurement value T is less than the target value T ₀ (ie, stage 1). After the gas dissolution amount is controlled in any of the following (1) to (4) and the measured value T reaches the target value T ₀ (that is, the steps 2 and 3) The gas dissolution amount of the gas dissolution water may be controlled by any one of the following (2) to (4).
(1) The gas dissolution amount of the gas dissolved water is controlled using the saturation solubility of the gas to be dissolved at the target value T ₀ obtained in advance as the adjustment value of the dissolved gas concentration.
(2) A continuous calibration relationship between the liquid temperature of the gas-dissolved water and the saturated solubility of the gas to be dissolved is obtained in advance, and the saturated solubility at the measured value T obtained from the calibration relationship is calculated as the dissolved gas concentration. The gas dissolution amount of the gas dissolution water is controlled as an adjustment value.
(3) A calibration relationship between the liquid temperature of the gas-dissolved water and the saturated solubility of the gas to be dissolved is obtained in advance at a predetermined liquid temperature interval, and the measured value T of the liquid temperatures indicated in the calibration relationship is obtained. And the amount of dissolved gas in the gas dissolved water is controlled using the saturation solubility at the liquid temperature closest to the measured value T as the adjusted value of the dissolved gas concentration.
(4) A calibration relationship between the liquid temperature of the gas-dissolved water and the saturated solubility of the gas to be dissolved is obtained in advance at a predetermined liquid temperature interval, and the measured value T reaches the liquid temperature indicated by the calibration relationship. In some cases, the amount of gas dissolved in the gas dissolved water is controlled using the saturation solubility at the liquid temperature as an adjustment value of the dissolved gas concentration.

  Here, “controlling the amount of dissolved gas based on the saturation solubility” means controlling the amount of dissolved gas using the saturation solubility as an adjustment value (target value) of the dissolved gas concentration of the obtained dissolved gas. .

  The calibration relationship between the liquid temperature and the saturated solubility may be obtained continuously or may be obtained at predetermined liquid temperature intervals. For example, the relationship between the liquid temperature and the saturation solubility at the liquid temperature at a liquid temperature interval of 10 ° C. or less may be obtained. If this liquid temperature interval is larger than 10 ° C., accurate control cannot be performed, and foaming may not be reliably prevented. Moreover, the gas-dissolved water with the dissolved gas concentration close to the saturation solubility may not be produced.

  The liquid temperature interval is preferably as small as possible from the viewpoint of performing high-precision control, but the liquid temperature interval is preferably set to about 1 to 10 ° C. in consideration of the work for measuring the calibration relationship and the control accuracy.

As a method for controlling the amount of dissolved gas based on the calibration relationship, for example, as in Example 1 described later, the liquid temperature and the saturation solubility at the liquid temperature at appropriate liquid temperature intervals (for example, 10 ° C. or less). The calibration relationship is obtained in advance, and the liquid temperature of the heated gas dissolved water at the heater outlet is measured at regular intervals, and the saturation solubility at the closest liquid temperature higher than the measured value T among the calibration temperature is measured. As a method for adjusting the dissolved gas concentration of the dissolved gas, there is a method of controlling the amount of dissolved gas (above (3)).
Also, the temperature of the heated gas dissolved water at the heater outlet is continuously measured, and the saturated solubility of the liquid temperature that becomes the temperature rise relay point when the calibration related liquid temperature is reached is used as the adjustment value of the dissolved gas concentration. The amount of dissolution may be controlled ((4) above).

For example, when raising the temperature of hydrogen gas-dissolved water with a liquid temperature of 5 ° C., first adjust the output of the pressurized pump of the gas to be dissolved with a saturation solubility of 1.72 mg / L at 10 ° C. as the adjustment value of the dissolved gas concentration. When heating starts and the heater output gradually rises and the heater outlet temperature reaches 10 ° C, the operation of changing the dissolved gas concentration adjustment value to 1.59 mg / L of saturated solubility at 20 ° C is repeated every 10 ° C. Can control the amount of dissolved gas.
Although the above shows an example in increments of 10 ° C., as described above, control with higher accuracy is possible as the calibration-related liquid temperature interval is smaller.

When controlling the amount of dissolved gas by intermittently measuring the temperature of the heated gas dissolved water, there is no particular limitation on the frequency, and it depends on the rate of temperature increase of the gas dissolved water during heating and the degree of fluctuation of the liquid temperature. different, for example, measurement and control spacing liquid temperature may be constant at 60 seconds, the Atsushi Nobori process to reach the target value T ₀ (step 1), reached the target value T _0, the liquid temperature The liquid temperature measurement / control interval may be set to different conditions after the time when the large fluctuation disappears (step 2 and step 3).

[Control of heating intensity]
The heating intensity of the gas dissolved water is preferably controlled based on the measured value T of the liquid temperature of the heated gas dissolved water. In particular, the flow rate of the supplied water or the amount of gas dissolved water flowing into the heating means is measured, It is preferable to control based on the measured value and the measured value T of the liquid temperature. That is, if the measured value T of the liquid temperature approaches the target value T _0, or measurements of the liquid temperature After exceeds the target value T _0, decreasing the heating intensity.

[Heating temperature and saturation solubility ratio]
In the present invention, in particular, the liquid temperature of the feed water is 20 ° C. or higher, for example, 20 to 30 ° C., the rising temperature of the gas dissolved water by heating is 10 ° C. or higher, particularly about 10 to 70 ° C., and the liquid temperature is 40 to 90 °. As in the case of producing heated gas-dissolved water at about 0 ° C., this is effective for producing heated gas-dissolved water in which the change in saturation solubility of the gas to be dissolved by heating is large.

In producing such heated gas-dissolved water, according to the present invention, when the target value T _{0 of} the heated gas-dissolved water temperature is less than 80 ° C., the saturated solubility ratio calculated by the following formula is 70% or more. Gas-dissolved water can be produced. In particular, when the target value T ₀ is less than 70 ° C., gas-dissolved water having a saturation solubility ratio of 80% or more can be produced.
Saturation solubility ratio = (S _X / S) × 100
(In the above formula, S represents the saturation solubility at the measured value T, and S _X represents the dissolved gas concentration of the gas dissolved water.)

[Production equipment for dissolved gas]
Hereinafter, an embodiment of the gas dissolved water production apparatus of the present invention will be described with reference to FIG. 1. FIG. 1 shows an example of an embodiment of the gas dissolved water production apparatus of the present invention. The gas-dissolved water production apparatus of the present invention is not limited to that shown in FIG.

In FIG. 1, 1 is a degassing membrane module, 2 is a gas dissolution membrane module, 3 is a heater, and 4 is a controller. V ₁ and V ₂ are open / close valves.

  The inside of the deaeration membrane module 1 is partitioned into a liquid phase chamber 1a and a gas phase chamber 1b by a gas permeable membrane 1M. Similarly, the gas dissolution membrane module 2 is also divided into a liquid phase chamber 2a and a gas phase chamber 2b by a gas permeable membrane 2M.

  The gas permeable membranes 1M and 2M are not particularly limited as long as they do not allow water to permeate and allow gas to permeate. For example, polypropylene, polydimethylsiloxane, polycarbonate-polydimethylsiloxane block copolymer, polyvinylphenol Examples thereof include polymer films such as polydimethylsiloxane-polysulfone block copolymer, poly (4-methylpentene-1), poly (2,6-dimethylphenylene oxide), and polytetrafluoroethylene.

Supply water (raw water) is introduced into the liquid phase chamber 1a of the degassing membrane module 1 from the raw water piping 11, and the gas phase chamber 1b of the degassing membrane module ₁ is sucked by the vacuum pump P1 through the exhaust piping 13. Is degassed.

There is no particular limitation on the vacuum pump P _1, for example, such as a scroll pump with liquid ring vacuum pumps and steam removal function and that can be used in the intake steam.

Deaerated water from the deaeration membrane module 1 is introduced into the liquid phase chamber 2 a of the gas dissolution membrane module 2 through the deaeration water pipe 12. The gas phase chamber 2b of the gas dissolving membrane module 2, the dissolved gases are supplied through the dissolved gas pipe 14 by the pressure pump P _2, the dissolved gases are dissolved in degassed water passes through the gas permeable membrane 2M Is done.

  The gas-dissolved water from the gas-dissolving membrane module 2 is supplied to the heater 3 through the pipe 15 and heated, and the heated gas-dissolved water is supplied from the pipe 16 to a washing machine or the like at the place of use.

This pipe 16 is provided with a thermometer T _m, the liquid temperature of the heating gas dissolved water is measured, the measured value T is input to the control unit 4. The controller 4 sets a target dissolved gas concentration adjustment value from a preset calibration relationship between the liquid temperature and the saturation solubility based on the input measurement value T, and a gas dissolution amount corresponding to the adjustment value. and so that, to control the output of the pressure pump P ₂ of the dissolution gas pipe 14.

The control unit 4 is further based on the measured value T of the thermometer T _m, it may be configured to control the heating intensity of the heater 3. Furthermore, a flow meter is provided in the piping 15 or 16, the measured value of the flowmeter, based on the measured value T of the thermometer T _m, may be configured to control the heating intensity of the heater 3.

In FIG. 1, reference numeral 17 denotes a blow pipe for discharging heated gas dissolved water during heating process or trouble of the heater to the outside of the system, and the heated gas dissolving is appropriately performed by opening and closing the valves V ₁ and V _2. The water destination is controlled.

[To be cleaned]
The heated gas-dissolved water produced by the present invention is useful as a cleaning liquid for various parts because it has a high temperature and a high dissolved gas concentration and is excellent in cleaning effect. There are no particular restrictions on the object to be cleaned, but due to its excellent cleaning effect, a high degree of cleanliness is required, such as silicon wafers for semiconductors, glass substrates for flat panel displays, and quartz substrates for photomasks. It is suitable for cleaning of electronic materials (electronic parts, electronic members, etc.) to be used.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

In the following Examples and Comparative Examples, ultrapure water was used as feed water, and after deaeration treatment with a deaeration membrane module: “Liquicel G248” manufactured by Millipore, a gas dissolution membrane module: “GNH-01R” manufactured by Japan Gore-Tex The dissolved gas was dissolved to produce gas-dissolved water, and the gas-dissolved water was heated with a heater: “DI WATER HEATER, HDWII-12N” manufactured by Omega Semicon Electronics Co., Ltd.
The dissolved gas concentration was measured by “510 Series Gas Analyzer” manufactured by ORBISPHERE.

[Comparative Example 1]
The target value T ₀ is set to 66 ° C., the temperature is raised without controlling the amount of dissolved gas based on the measured value T of the gas dissolved water after heating, and the saturated solubility ratio (dissolved gas at the measured value T is measured). The ratio of concentration to saturation solubility S) was determined. The adjustment value of the dissolved gas concentration was set at a target value T ₀ : saturated solubility So at 66 ° C .: 1.07 mg / L, and the conditions were fixed, so the saturated solubility ratio was (So / S) × 100 (%). Become.
As a result, as shown in Table 3 below, since the amount of dissolved gas was not controlled, the saturation solubility ratio was less than 80% until nearly 30 seconds after the start of heating, and after the heating time of 70 seconds passed, There were times when the solubility ratio exceeded 100%, which resulted in the possibility of foaming.

[Example 1]
The target value T ₀ was set to 66 ° C., and the temperature was raised while controlling the amount of dissolved gas based on the measured value T of the liquid temperature of the dissolved gas after heating.
In this control, the saturated solubility at each liquid temperature is obtained in advance at intervals of 5 ° C. or 10 ° C., and as shown in Table 2 below, for example, when the measured value T is 25 ° C. or higher and lower than 30 ° C., the dissolved gas concentration Was adjusted to the saturation solubility S _X at 30 ° C. to adjust the gas dissolution amount.

The saturation solubility ratio at this time (the ratio Sx / S × 100 (%) of the dissolved gas concentration S _x at the measurement value T and the saturation solubility S at the measurement value T) was determined.
As shown in Table 3, the result is that the gas dissolution amount is controlled based on the measured value T of the liquid temperature, so that the saturation solubility ratio is stably maintained at 90% or more regardless of the change in the saturation solubility due to the temperature rise. In addition, since the saturated solubility ratio did not exceed 100%, foaming could be prevented.

[Examples 2 to 4]
As gas species, oxygen gas (Example 2), hydrogen gas (Example 3), and nitrogen gas (Example 4) were used, respectively, and degassing, gas dissolution, and heating were performed in the same manner as in Example 1. When the dissolved water was produced, the saturation solubility ratio was determined when the gas dissolution amount was controlled at intervals of 10 ° C. of the liquid temperature.
Conditions and results are shown in Tables 4 to 6 below.
Any gas type can maintain a saturation solubility ratio of 70% or more by controlling in increments of 10 ° C if the heating temperature is less than 80 ° C, and saturated by controlling in increments of 10 ° C if the heating temperature is less than 70 ° C. It was shown that the solubility ratio of 80% or more can be maintained, and that the saturation solubility ratio does not exceed 100%.

1 Degassing membrane module 2 Gas dissolution membrane module 3 Heater 4 Controller

Claims (6)

A gas dissolution process including a gas dissolution process for dissolving a gas to be dissolved, which is a gas that does not self-decompose in water, in a supply water, and a heating process for heating the obtained gas dissolution water to a target value T ₀ of the liquid temperature. In the method for producing water, based on the measured value T of the temperature of the dissolved gas after heating in the heating step, the dissolved gas concentration of the dissolved gas does not exceed the saturation solubility at the measured value T. A method for controlling the amount of gas dissolved in the gas dissolving step ,
When the measured value T is less than the target value T ₀ , the gas dissolution amount of the gas-dissolved water is controlled by any one of the following (1) to (4), and the measured value T becomes the target value T ₀ . After reaching , the gas-dissolved water production method characterized in that the gas-dissolved water amount is controlled by any one of the following (2) to (4) .
(1) The gas dissolution amount of the gas dissolved water is controlled using the saturation solubility of the gas to be dissolved at the target value T ₀ determined in advance as the adjustment value of the dissolved gas concentration.
(2) A continuous calibration relationship between the liquid temperature of the gas-dissolved water and the saturated solubility of the gas to be dissolved is obtained in advance, and the saturated solubility at the measured value T obtained from the calibration relationship is calculated as the dissolved gas concentration. The gas dissolution amount of the gas dissolution water is controlled as an adjustment value.
(3) A calibration relationship between the liquid temperature of the gas-dissolved water and the saturated solubility of the gas to be dissolved at the liquid temperature is obtained in advance at a predetermined liquid temperature interval of a liquid temperature interval of 10 ° C. or less, and is shown in the calibration relationship. The amount of dissolved gas in the gas dissolved water is controlled using the saturated solubility at a liquid temperature higher than the measured value T and closest to the measured value T as an adjustment value of the dissolved gas concentration.
(4) A calibration relationship between the liquid temperature of the gas-dissolved water and the saturated solubility of the gas to be dissolved at the liquid temperature is obtained in advance at a predetermined liquid temperature interval of a liquid temperature interval of 10 ° C. or less. When the liquid temperature indicated in the calibration relationship is reached, the gas dissolution amount of the gas dissolved water is controlled using the saturation solubility at the liquid temperature as an adjustment value of the dissolved gas concentration. Oite to claim 1, wherein the liquid temperature of the feed water is at 20 ° C. or higher, the manufacturing method of the gas dissolved water, wherein the elevated temperature of the gas dissolved water by the heating is 10 ° C. or higher. 3. The method for producing gas-dissolved water according to claim 1, wherein the target value T ₀ is less than 80 ° C., and a saturated solubility ratio calculated by the following formula is 70% or more.
Saturation solubility ratio = (S _X / S) × 100
(In the above formula, S represents the saturation solubility at the measured value T, and S _X represents the dissolved gas concentration of the gas-dissolved water.) According to claim 3, wherein a target value T ₀ is less than 70 ° C., the manufacturing method of the gas dissolved water, characterized in that the saturation solubility ratio of 80% or more. In any one of claims 1 to 4, a manufacturing method of the gas dissolved water, characterized by controlling the heating intensity of the gas dissolved water based on the measured value T. In Claim 5 , the amount of inflows into the heating step of the gas dissolved water is measured, and based on the measured value of the amount of inflow of the gas dissolved water and the measured value T, the heating intensity of the gas dissolved water is determined. A method for producing gas-dissolved water, characterized by controlling.

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