JP2012139656A - Method and system for making nitrogen gas-dissolved water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and system for making nitrogen gas-dissolved water constituted so as to be continuously and stably operated over a long period of time by efficiently performing the discharge of condensed water in making the nitrogen gas-dissolved water by dissolving nitrogen gas in pure water or ultrapure water.SOLUTION: In the method for making the nitrogen gas-dissolved water by dissolving the nitrogen gas in pure water or ultrapure water using a gas dissolving membrane module 2 equipped with a gaseous phase chamber 22 and a liquid phase chamber 23 demarcated by a gas permeable membrane 21, the condensed water produced in the gaseous phase chamber 22 is introduced into the condensed water discharge part 4 connected to the gaseous phase chamber 22 to cut off the connection of the condensed water discharge part 4 with the gaseous phase chamber 22. The nitrogen gas is supplied to the condensed water discharge part 4 in a state that the connection with the gaseous phase chamber 22 is cut off to discharge the condensed water introduced into the condensed water discharge part 4.

Description

  The present invention relates to a nitrogen gas-dissolved water production method and a nitrogen gas-dissolved water production system for producing nitrogen gas-dissolved water by dissolving nitrogen gas in pure water or ultrapure water.

  Conventionally, in order to remove fine particles, organic substances, metals, etc. from the surface of electronic materials such as silicon wafers for semiconductors and glass substrates for flat panel displays, a high concentration based on hydrogen peroxide called RCA cleaning method A wet cleaning method at a high temperature with a chemical solution was performed. The RCA cleaning method is an effective method for removing metal or the like on the surface of the electronic material, but it is necessary to use a large amount of high-concentration acid, alkali, or hydrogen peroxide. Therefore, these large amounts of chemicals are discharged into the waste liquid, and there is a problem that a great burden is imposed on the neutralization treatment and precipitation treatment of the waste liquid and a large amount of sludge is generated. There is also a problem that a large amount of pure water or ultrapure water is required to rinse the object to be cleaned after cleaning.

  Therefore, gas-dissolved water prepared by dissolving a specific gas in pure water and adding a trace amount of chemicals as necessary has been used in place of high-concentration chemical solutions. If the cleaning is performed with gas-dissolved water, the burden of waste liquid treatment is reduced and the amount of cleaning water used can be reduced because the problem of chemical residue on the object to be cleaned is small and the cleaning effect is high. Specific gases used for the gas-dissolved water as the electronic material cleaning water include nitrogen gas, hydrogen gas, oxygen gas, ozone gas, rare gas, carbon dioxide gas, and the like.

  As a method for producing such gas-dissolved water, a method using a gas-dissolving membrane module having a gas phase chamber and a liquid phase chamber partitioned by a gas permeable membrane is known. The gas permeable membrane is a membrane that does not allow liquid such as water to pass therethrough but allows gas (gas) to pass therethrough. When a gas such as nitrogen gas is supplied to the gas phase chamber and pure water or ultrapure water is supplied to the liquid phase chamber, the nitrogen gas permeates the gas permeable membrane and dissolves in the pure water or ultrapure water in the liquid phase chamber. Gas dissolved water is produced. For example, in Patent Document 1, after degassing ultrapure water to lower the saturation level of dissolved gas, hydrogen gas is dissolved in the degassed ultrapure water using a gas dissolving membrane module. The technology is described.

  As described above, the gas permeable membrane does not allow liquid to permeate. However, when the gas-dissolved membrane module is used to dissolve the gas in pure water or ultrapure water, Part of the supplied pure water or ultrapure water becomes water vapor and permeates the gas permeable membrane and diffuses into the gas phase chamber. The water vapor that has permeated from the liquid phase chamber in this way is condensed in the gas phase chamber to become condensed water, and accumulates in the gas phase chamber.

  While the amount of such condensed water is small, the effect on the performance of the gas-dissolving membrane module is slight. However, when the amount of condensed water increases over time, the condensed water causes a gas-phase chamber of the gas permeable membrane. The surface on the side is covered, and the effective area contributing to gas permeation in the gas permeable membrane is reduced. As a result, the permeation of gas into the liquid phase chamber is not performed smoothly, so the performance of the gas dissolution membrane module is reduced, and the gas is sufficiently dissolved in pure water or ultrapure water supplied to the liquid phase chamber. Can not be made. In order to avoid such a situation, it is necessary to periodically discharge condensed water accumulated in the gas phase chamber of the gas dissolution membrane module to the outside of the system.

Japanese Patent Laid-Open No. 11-077023

  As a method of discharging condensed water accumulated in the gas phase chamber of the gas dissolution membrane module to the outside of the system, a vacuum pump or an ejector is connected to the gas phase chamber via a discharge pipe, and the condensed water accumulated in the gas phase chamber is It is conceivable to suction and discharge with a vacuum pump or the like. However, when the condensed water in the gas phase chamber is sucked with a vacuum pump or the like, the pressure in the gas phase chamber is reduced, and the gas phase is transmitted from the gas phase chamber to the pure water or ultrapure water in the liquid phase chamber. Since the amount of gas decreases, there is a problem that the gas concentration of the dissolved gas decreases. Therefore, when condensate is discharged, after the condensed water is introduced into the discharge pipe, the valve on the gas dissolution membrane module side of the discharge pipe is closed to affect the gas phase chamber of the gas dissolution membrane module. It is necessary to make it unacceptable.

  On the other hand, when the valve on the gas dissolution membrane module side of the exhaust pipe is closed and the gas phase of the gas dissolution membrane module is not affected, the exhaust pipe is connected by a vacuum pump or ejector connected to the exhaust pipe. Even if it is attempted to discharge the condensed water by reducing the pressure, the gas does not flow into the gas phase chamber and the condensed water is not pushed out, which causes another problem that the condensed water is not discharged well from the discharge pipe.

  The present invention has been made in view of the above-mentioned problems, and in producing nitrogen gas-dissolved water by dissolving nitrogen gas in pure water or ultrapure water, the condensate is discharged efficiently, An object is to provide a nitrogen gas-dissolved water production method and a nitrogen gas-dissolved water production system that can be operated continuously and stably over a period of time.

  In order to achieve the above object, first, the present invention uses a gas dissolution membrane module having a gas phase chamber and a liquid phase chamber partitioned by a gas permeable membrane, and converts nitrogen gas into pure water or ultrapure water. A method of producing dissolved nitrogen gas dissolved water by introducing the condensed water generated in the gas phase chamber into a condensed water discharge portion connected to the gas phase chamber, and the condensed water discharge portion; Cutting the connection with the gas phase chamber, and supplying nitrogen gas to the condensate discharge portion in a state where the connection with the gas phase chamber is cut off, thereby introducing the condensate discharge portion into the condensate discharge portion. And a step of discharging condensed water. A method for producing dissolved nitrogen gas water is provided (Invention 1).

  According to the above invention (Invention 1), the condensate is removed even in a state where the connection between the condensed water discharge part and the gas-phase chamber of the gas-dissolving membrane module is shut off and the gas-dissolving membrane module is not affected. Since the nitrogen gas supplied to the discharge unit pushes out the condensed water introduced into the condensed water discharge unit, the condensed water can be discharged efficiently. As a result, condensed water that covers the surface of the gas permeable membrane on the gas phase chamber side does not stay in the gas phase chamber, and the performance of the gas dissolution membrane module does not deteriorate. Nitrogen gas-dissolved water in which nitrogen gas is continuously and stably dissolved in pure water or ultrapure water can be produced.

  In the above invention (Invention 1), the method further comprises the step of measuring the amount of the condensed water introduced into the condensed water discharge part, and in the step of cutting off the connection between the condensed water discharge part and the gas phase chamber. When the amount of the condensed water introduced into the condensed water discharge part exceeds a predetermined amount, it is preferable to disconnect the connection between the condensed water discharge part and the gas phase chamber (Invention 2).

  According to the said invention (invention 2), the condensed water introduce | transduced into the condensed water discharge part does not overflow from a condensed water discharge part, but can discharge condensed water at an appropriate timing.

  In the above inventions (Inventions 1 and 2), the step of discharging the condensed water supplies nitrogen gas to the condensed water discharging unit in a state where the connection with the gas phase chamber is cut off, and the condensed water discharging unit It is preferable to discharge the condensed water introduced into the condensed water discharge part by depressurizing (Convention 3).

  According to the above invention (Invention 3), the condensed water can be sucked by depressurizing the condensed water discharge part while pushing out the condensed water staying in the condensed water discharge part by the supplied nitrogen gas. The condensed water can be discharged more efficiently.

  In the above invention (Invention 3), the condensed water discharge part may be decompressed by a vacuum pump (Invention 4), or the condensed water discharge part may be decompressed by an ejector (Invention 5).

  Secondly, the present invention provides a gas-dissolved membrane module having a gas phase chamber and a liquid phase chamber partitioned by a gas permeable membrane, and a condensed water discharge device for discharging condensed water generated in the gas phase chamber. A system for producing dissolved nitrogen gas, wherein the condensed water discharge device is connected to the gas phase chamber, the condensed water discharge unit into which condensed water generated in the gas phase chamber is introduced, and the condensation Nitrogen gas-dissolved water production comprising: a valve capable of interrupting connection between a water discharge part and the gas phase chamber; and a nitrogen gas supply device for supplying nitrogen gas to the condensed water discharge part A system is provided (Invention 6).

  According to the above invention (Invention 6), the connection between the condensed water discharge part and the gas-phase chamber of the gas-dissolving membrane module is blocked by a valve, and even in a state where the gas-dissolving membrane module has no influence on the gas-phase chamber, Since the nitrogen gas supplied to the condensed water discharge unit by the nitrogen gas supply device pushes out the condensed water introduced into the condensed water discharge unit, the condensed water can be discharged efficiently. As a result, condensed water that covers the surface of the gas permeable membrane on the gas phase chamber side does not stay in the gas phase chamber, and the performance of the gas dissolution membrane module does not deteriorate. Nitrogen gas-dissolved water in which nitrogen gas is continuously and stably dissolved in pure water or ultrapure water can be produced.

  In the said invention (invention 6), the said condensed water discharge | emission apparatus is further equipped with the measuring apparatus which measures the quantity of the said condensed water introduced into the said condensed water discharge part, The said condensed water measured by the said measurement apparatus When the amount exceeds a predetermined amount, the valve preferably disconnects the connection between the condensed water discharge part and the gas phase chamber (Invention 7).

  According to the said invention (invention 7), the condensed water introduce | transduced into the condensed water discharge part does not overflow from a condensed water discharge part, but can discharge condensed water at an appropriate timing.

  In the said invention (invention 6 and 7), it is preferable that the said condensed water discharge apparatus is further equipped with the pressure reduction means which pressure-reduces the said condensed water discharge part (invention 8).

  According to the above invention (Invention 8), the condensed water can be sucked by depressurizing the condensed water discharge part while extruding the condensed water staying in the condensed water discharge part by the supplied nitrogen gas. The condensed water can be discharged more efficiently.

  In the said invention (invention 8), the said pressure reduction means may be a vacuum pump (invention 9), and may be an ejector (invention 10).

  According to the nitrogen gas-dissolved water production method and the nitrogen gas-dissolved water production system of the present invention, condensed water can be discharged efficiently, and nitrogen gas can be purified continuously or stably over a long period of time with pure water or Nitrogen gas-dissolved water dissolved in ultrapure water can be produced.

It is the schematic which shows the nitrogen gas dissolved water manufacturing system which concerns on one Embodiment of this invention. It is the schematic which shows the nitrogen gas dissolved water manufacturing system which concerns on other embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a nitrogen gas dissolved water production system 1 according to this embodiment includes a gas dissolved membrane module 2, a nitrogen gas supply device 3, a condensed water discharge unit 4, an exhaust gas supply device 5, and a vacuum pump 6. It is configured.

  The gas dissolution membrane module 2 is partitioned into a gas phase chamber 22 and a liquid phase chamber 23 by a gas permeable membrane 21. A raw water supply pipe 24 and a gas-dissolved water supply pipe 25 are connected to the liquid phase chamber 23, and raw water W produced by a pure water production apparatus (not shown) is dissolved into the gas via the raw water supply pipe 24. Gas dissolved water supplied to the membrane module 2 and manufactured in the gas dissolved membrane module 2 is supplied to a cleaning device (not shown) via the gas dissolved water supply pipe 25. A nitrogen gas supply device 3 is connected to the gas phase chamber 22 via a gas supply pipe 31. A nitrogen gas supply control valve 32 for adjusting the flow rate of nitrogen gas supplied from the nitrogen gas supply device 3 to the gas phase chamber 22 is provided in the middle of the gas supply pipe 31. Further, the gas phase chamber 22 is connected to a condensed water discharge portion 4 for discharging condensed water generated in the gas phase chamber 22.

  The gas permeable membrane 21 is not particularly limited as long as it does not transmit water and allows gas to pass. For example, polypropylene, polydimethylsiloxane, polycarbonate-polydimethylsiloxane block copolymer, polyvinylphenol-polydimethylsiloxane. -Polysulfone block copolymers, polymer films such as poly (4-methylpentene-1), poly (2,6-dimethylphenylene oxide), polytetrafluoroethylene and the like.

  As the raw water W, pure water or ultrapure water purified to such an extent that the object to be cleaned can be cleaned to the required cleanliness level is generally used. However, the raw water W is not limited to this and is used at a use point. Water that has a cleanliness that satisfies the intended use and does not contain a substance that can easily degrade or alter the gas permeable membrane. Moreover, you may use the deaerated water which performed the deaeration process.

  The condensed water discharge part 4 includes a tubular condensed water discharge pipe 40, a first valve 41 provided near the middle upstream of the condensed water discharge pipe 40, and a second provided near the middle downstream of the condensed water discharge pipe 40. It consists of a valve 42 and a measuring instrument 43 provided in the middle of the condensed water discharge pipe 40 and on the primary side of the first valve 41. The upstream end of the condensed water discharge pipe 40 is connected to the gas phase chamber 22 of the gas dissolution membrane module 2. Further, the exhaust gas supply device 5 is connected to the condensed water discharge pipe 40 through the exhaust gas supply pipe 51 at a position near the first valve 41 between the first valve 41 and the second valve 42. . An exhaust gas supply control valve 52 for adjusting the flow rate of nitrogen gas supplied from the exhaust gas supply device 5 to the exhaust gas supply pipe 51 is provided in the middle of the exhaust gas supply pipe 51. Further, the vacuum pump 6 is connected to the downstream end of the condensed water discharge pipe 40.

  The measuring device 43 is a liquid level gauge (level sensor) that detects the level of condensed water accumulated in the condensed water discharge pipe 40. In the present embodiment, a liquid level gauge is used as the measuring device 43 for measuring the amount of condensed water accumulated in the condensed water discharge pipe 40. For example, a weight measuring device for measuring the weight of accumulated condensed water is used. May be. The measuring device 43 may be a liquid level meter that uses light, or may be a liquid level meter that uses ultrasonic waves, capacitance, or the like. In the present embodiment, the measuring instrument 43 is provided on the primary side of the first valve 41. In other words, when the measuring device 43 detects the liquid level of the condensed water, the liquid level of the condensed water is located on the primary side of the first valve 41. Therefore, when the first valve 41 is closed in the condensed water discharge step, a part of the condensed water is left on the primary side of the first valve 41, and the first valve 41 is opened to discharge the condensed water. When the process is completed, the remaining condensed water flows into the secondary side of the first valve 41, so that the exhaust gas is prevented from flowing into the primary side of the first valve 41. As a result, the gas dissolved water is hardly contaminated by the exhaust gas.

  The exhaust gas supply device 5 is a device that supplies nitrogen gas to the condensed water discharge pipe 40, and is between the first valve 41 and the second valve 42 of the condensed water discharge pipe 40 and close to the first valve 41. It is connected to the position via an exhaust gas supply pipe 51. When the exhaust gas supply device 5 is connected to such a position, the nitrogen gas is supplied from the exhaust gas supply device 5 to the condensed water discharge pipe 40 in a state where the first valve 41 is closed. The condensed water in which the nitrogen gas stays in the condensed water discharge pipe 40 is pushed out toward the second valve 42, and the condensed water can be discharged efficiently.

  Although there is no restriction | limiting in particular in the vacuum pump 6, What can take in water vapor | steam like a water-sealed vacuum pump, a scroll pump provided with the water vapor removal function, etc. is preferable, for example. By operating the exhaust gas supply device 5 to supply nitrogen gas to the condensed water discharge pipe 40 and operating the vacuum pump 6, the condensed water staying in the condensed water discharge pipe 40 by the supplied nitrogen gas. Since the vacuum pump 6 depressurizes the condensed water discharge pipe 40 and sucks the condensed water while pushing out the condensed water, the condensed water can be discharged more efficiently.

  In the present embodiment, the vacuum pump 6 is provided as a decompression device for decompressing the inside of the condensed water discharge pipe 40. However, the present invention is not limited to this. For example, as shown in FIG. Instead of this, the ejector 7 may be provided, or such a decompression device may not be provided. The nitrogen gas dissolved water manufacturing system 1A shown in FIG. 2 has the same configuration as the nitrogen gas dissolved water manufacturing system 1 shown in FIG. 1 except that an ejector 7 is provided instead of the vacuum pump 6. Therefore, detailed description thereof is omitted.

  In order to produce nitrogen gas-dissolved water using the nitrogen gas-dissolved water production system 1 configured as described above, first, raw water W produced by a pure water production apparatus (not shown) is supplied from the raw water supply pipe 24 to the gas. Supply to the liquid phase chamber 23 of the dissolved membrane module 2 is started. Further, the nitrogen gas supply control valve 32 is opened, and supply of nitrogen gas from the nitrogen gas supply device 3 to the gas phase chamber 22 of the gas dissolution membrane module 2 is started. At this time, the first valve 41 of the condensed water discharge unit 4 is closed. The second valve 42 of the condensed water discharge unit 4 is preferably closed, but may be opened.

  When raw water W is supplied to the liquid phase chamber 23 of the gas dissolution membrane module 2 and nitrogen gas is supplied to the gas phase chamber 22, the nitrogen gas permeates the gas permeable membrane 21 from the gas phase chamber 22 side to the liquid phase chamber 23 side. Dissolve in the raw water W in the liquid phase chamber 23. The nitrogen gas dissolved water thus obtained is supplied to the use point via the gas dissolved water supply pipe 25.

  Thus, in the process of producing the nitrogen gas dissolved water, a part of the raw water W supplied to the liquid phase chamber 23 of the gas dissolved membrane module 2 becomes water vapor and diffuses into the gas phase chamber 22 through the gas permeable membrane 21. Come on. The water vapor that has permeated from the liquid phase chamber 23 in this way is condensed in the gas phase chamber 22 to become condensed water, and begins to stay in the gas phase chamber 22.

  Here, the first valve 41 is opened with the second valve 42 of the condensed water discharge part 4 closed. Thereby, the condensed water generated in the gas phase chamber 22 is stored in the condensed water discharge pipe 40 of the condensed water discharge portion 4. Since the second valve 42 is closed, the amount of condensed water stored in the condensed water discharge pipe 40 gradually increases. This amount of condensed water is measured in the condensed water discharge pipe 40. Measured by instrument 43. In addition, in the process in which the condensed water generated in the gas phase chamber 22 is stored in the condensed water discharge pipe 40 of the condensed water discharge portion 4, the second valve 42 is closed, so that Gas and impurities are prevented from flowing into the gas-dissolving membrane module 2 through the condensed water discharge pipe 40.

  When the amount of condensed water stored in the condensed water discharge pipe 40 measured by the measuring device 43 exceeds a predetermined amount, the first valve 41 is closed and the second valve 42 is opened. The exhaust gas supply control valve 52 is also opened, and supply of nitrogen gas from the exhaust gas supply device 5 to the condensed water discharge pipe 40 is started. As a result, the condensed water stored in the condensed water discharge pipe 40 is pressed by the nitrogen gas, is pushed away toward the second valve 42, and is discharged from the condensed water discharge pipe 40 to the outside of the system. As described above, nitrogen gas is supplied from the exhaust gas supply device 5 to the condensed water discharge pipe 40. At this time, the first valve 41 is closed, so that the first valve 41 is closed. Nitrogen gas does not flow into the upstream side, and condensed water does not flow backward into the gas dissolution membrane module 2. Moreover, since the pressure in the gas phase chamber 22 of the gas dissolution membrane module 2 does not increase, the production of nitrogen gas dissolved water is stably continued.

  By using nitrogen gas as the gas supplied from the exhaust gas supply device 5 to the condensed water discharge pipe 40, the first valve 41 is opened again after the condensed water is discharged, and the condensed water discharge pipe 40 and the gas dissolution membrane module 2 are opened. When the connection with the gas phase chamber 22 is recovered, there is an advantage that the influence on the production of the nitrogen gas dissolved water in the gas dissolving membrane module 2 can be minimized. That is, after the condensed water is discharged, the condensed water discharge pipe 40 is filled with the gas supplied from the exhaust gas supply device 5, and in this state, the condensed water discharge pipe 40 and the gas phase chamber 22 of the gas dissolution membrane module 2 are filled. When the connection is restored, the gas also flows into the gas phase chamber 22 side. Here, if the gas is air or hydrogen gas, the amount of nitrogen gas passing through the gas permeable membrane 21 from the gas phase chamber 22 side to the liquid phase chamber 23 side will be affected. However, if the gas is nitrogen gas, the amount of nitrogen gas that permeates the gas permeable membrane 21 from the gas phase chamber 22 side to the liquid phase chamber 23 side is hardly affected, and nitrogen is stably stabilized in the liquid phase chamber 23. Gas-dissolved water can be produced.

  Thus, by supplying nitrogen gas to the condensed water discharge pipe 40, the condensed water stored in the condensed water discharge pipe 40 is discharged out of the system. At this time, the vacuum pump 6 is operated. When the inside of the condensed water discharge pipe 40 is depressurized, the condensed water remaining in the condensed water discharge pipe 40 is pushed out by the supplied nitrogen gas, and the vacuum pump 6 depressurizes the condensed water discharge pipe 40 to condense. Since water is sucked, condensed water can be discharged more efficiently.

  After the condensed water stored in the condensed water discharge pipe 40 is discharged, the second valve 42 and the exhaust gas supply control valve 52 are closed and the first valve 41 is opened to discharge the condensed water. Is completed. This discharging step may be repeated a predetermined number of times every predetermined time, or may be appropriately performed while observing the production status of the nitrogen gas dissolved water.

  By performing the condensate discharge process as described above, the first valve 41 provided in the condensate discharge pipe 40 is closed so that the gas dissolution chamber module 2 is not affected by the gas phase chamber 22. Even when the condensed water stored in the condensed water discharge pipe 40 is discharged, the nitrogen gas supplied from the exhaust gas supply device 5 to the condensed water discharge pipe 40 is contained in the condensed water discharge pipe 40. Since the stored condensed water is pushed out of the system, the condensed water can be efficiently discharged. Moreover, as a result, the condensed water which covers the surface of the gas permeable membrane 21 on the gas phase chamber 22 side does not stay in the gas phase chamber 22, and the performance of the gas dissolution membrane module 2 does not deteriorate. Therefore, it is possible to produce nitrogen gas-dissolved water in which nitrogen gas is dissolved in pure water or ultrapure water continuously and stably over a long period of time. Furthermore, when the gas supplied from the exhaust gas supply device 5 to the condensed water discharge pipe 40 is nitrogen gas, the gas dissolving membrane module 2 can also be used when the first valve 41 is opened again after the condensed water is discharged. The influence on the production of the nitrogen gas-dissolved water can be minimized, and the nitrogen gas-dissolved water can be produced stably.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention in detail, this invention is not limited at all by these Examples.

[Example 1]
In the nitrogen gas dissolved water production system shown in FIG. 2, ultrapure water is used as raw water W that passes through the liquid phase chamber 23 of the gas dissolved membrane module 2, and nitrogen gas is supplied to the gas phase chamber 22 from the nitrogen gas supply device 3. Then, nitrogen gas-dissolved water was produced with the first valve 41 of the condensed water discharge unit 4 opened and the second valve 42 closed. When the dissolved oxygen concentration in the produced nitrogen gas-dissolved water was measured, the dissolved oxygen concentration was around 5 μg / L.

  Thereafter, when the measuring device 43 (level sensor) senses the condensed water stored in the condensed water discharge section 4, the first valve 41 is closed, the second valve 42 is opened, and the exhaust gas supply control valve 52 is opened. When the nitrogen gas was supplied to the condensed water discharge pipe 40 at 1 NL / min for 10 seconds, the amount of residual condensed water in the section from the first valve 41 to the second valve 42 of the condensed water discharge pipe 40 was The volume of the section from the first valve 41 to the second valve 42 of the condensed water discharge pipe 40 was about 10%.

  After the condensed water is discharged from the condensed water discharge pipe 40, the first valve 41 is opened, the second valve 42 is closed, the exhaust gas supply control valve 52 is closed, and the dissolved oxygen concentration in the nitrogen gas dissolved water immediately after is opened. Was measured, and the dissolved oxygen concentration was around 5 μg / L. That is, the dissolved oxygen concentration of the nitrogen gas-dissolved water produced by the gas-dissolving membrane module 2 after performing the condensed water discharging step did not rise more than before the condensating water discharging step.

[Example 2]
In the nitrogen gas dissolved water production system shown in FIG. 2, the condensed water is supplied from the condensed water discharge pipe 40 in the same manner as in Example 1 except that the nitrogen gas is supplied to the condensed water discharge pipe 40 and the ejector 7 is operated. When discharged, the residual amount of condensed water in the section from the first valve 41 to the second valve 42 of the condensed water discharge pipe 40 is the volume of the section from the first valve 41 to the second valve 42 of the condensed water discharge pipe 40. Of less than 5%.

  After the condensed water is discharged from the condensed water discharge pipe 40, the first valve 41 is opened, the second valve 42 is closed, the exhaust gas supply control valve 52 is closed, and the dissolved oxygen concentration in the nitrogen gas dissolved water immediately after is opened. Was measured, and the dissolved oxygen concentration was around 5 μg / L.

Example 3
In the nitrogen gas dissolved water production system shown in FIG. 1, condensed water is supplied from the condensed water discharge pipe 40 in the same manner as in Example 1 except that nitrogen gas is supplied to the condensed water discharge pipe 40 and the vacuum pump 6 is operated. As a result, the remaining amount of condensed water in the section from the first valve 41 to the second valve 42 of the condensed water discharge pipe 40 is equal to that in the section from the first valve 41 to the second valve 42 of the condensed water discharge pipe 40. Less than 5% of the volume.

  After the condensed water is discharged from the condensed water discharge pipe 40, the first valve 41 is opened, the second valve 42 is closed, the exhaust gas supply control valve 52 is closed, and the dissolved oxygen concentration in the nitrogen gas dissolved water immediately after is opened. Was measured, and the dissolved oxygen concentration was around 5 μg / L.

[Comparative Example 1]
In the nitrogen gas dissolved water production system shown in FIG. 2, ultrapure water is used as raw water W that passes through the liquid phase chamber 23 of the gas dissolved membrane module 2, and nitrogen gas is supplied to the gas phase chamber 22 from the nitrogen gas supply device 3. Then, nitrogen gas-dissolved water was produced with the first valve 41 of the condensed water discharge unit 4 opened and the second valve 42 closed. When the dissolved oxygen concentration in the produced nitrogen gas-dissolved water was measured, the dissolved oxygen concentration was around 5 μg / L.

  Thereafter, when the measuring device 43 (level sensor) senses the condensed water stored in the condensed water discharge section 4, the first valve 41 is closed, the second valve 42 is opened, and the exhaust gas supply control valve 52 is opened. When the valve is used and air is supplied to the condensate discharge pipe 40 instead of nitrogen gas at 1 NL / min for one minute, the condensate remains in the section from the first valve 41 to the second valve 42 of the condensate discharge pipe 40. The amount was about 10% of the volume of the section from the first valve 41 to the second valve 42 of the condensed water discharge pipe 40.

  After the condensed water is discharged from the condensed water discharge pipe 40, the first valve 41 is opened, the second valve 42 is closed, the exhaust gas supply control valve 52 is closed, and the dissolved oxygen concentration in the nitrogen gas dissolved water immediately after is opened. Was measured, and the dissolved oxygen concentration was around 30 μg / L. That is, the dissolved oxygen concentration of the nitrogen gas-dissolved water produced by the gas-dissolved membrane module 2 after performing the condensed water discharging step increased from before the condensed water discharging step.

[Comparative Example 2]
In the nitrogen gas dissolved water production system shown in FIG. 2, nitrogen gas dissolved water is produced by the same method as in Comparative Example 1, and then the measuring device 43 (level sensor) removes the condensed water stored in the condensed water discharge unit 4. Upon detection, the first valve 41 is closed, the second valve 42 is opened, the exhaust gas supply control valve 52 is closed, and the ejector 7 is operated without supplying gas to the condensed water discharge pipe 40. As a result, the residual amount of condensed water in the section from the first valve 41 to the second valve 42 of the condensed water discharge pipe 40 is the volume of the section from the first valve 41 to the second valve 42 of the condensed water discharge pipe 40. About 20%.

  According to the above examples and comparative examples, the nitrogen gas supplied from the exhaust gas supply device 5 to the condensed water discharge pipe 40 pushes the condensed water stored in the condensed water discharge pipe 40 out of the system. It was confirmed that the condensed water can be discharged. Further, it was confirmed that the condensed water can be discharged more efficiently by supplying the nitrogen gas to the condensed water discharge pipe 40 and operating the vacuum pump 6 and the ejector 7. As a result, since the performance of the dissolved membrane module 2 does not deteriorate, it is possible to produce nitrogen gas-dissolved water in which nitrogen gas is dissolved in pure water or ultrapure water continuously and stably over a long period of time. confirmed. Further, by supplying nitrogen gas to the condensed water discharge pipe 40, the dissolved oxygen concentration gas of the nitrogen gas dissolved water is not affected even after the condensed water discharging step is performed, and nitrogen can be stably added. It was confirmed that gas-dissolved water can be produced.

  The present invention is useful for producing nitrogen gas-dissolved water by efficiently dissolving nitrogen gas in pure water or ultrapure water.

DESCRIPTION OF SYMBOLS 1,1A ... Nitrogen gas dissolved water manufacturing system 2 ... Gas dissolved membrane module 21 ... Gas permeable membrane 22 ... Gas phase chamber 23 ... Liquid phase chamber 24 ... Raw water supply pipe 25 ... Gas dissolved water supply pipe 3 ... Nitrogen gas supply apparatus 31 ... Nitrogen gas supply pipe 32 ... Nitrogen gas supply control valve 4 ... Condensate discharge part 40 ... Condensate discharge pipe 41 ... First valve 42 ... Second valve 43 ... Measurement instrument 5 ... Exhaust gas supply device 51 ... Exhaust gas supply pipe 52 ... Exhaust gas supply control valve 6 ... Vacuum pump 7 ... Ejector

Claims (10)

A method for producing nitrogen gas-dissolved water by dissolving a nitrogen gas in pure water or ultrapure water using a gas-dissolving membrane module having a gas phase chamber and a liquid phase chamber partitioned by a gas permeable membrane,
Introducing the condensed water generated in the gas phase chamber into a condensed water discharge unit connected to the gas phase chamber;
Cutting off the connection between the condensed water discharger and the gas phase chamber;
Discharging the condensed water introduced into the condensed water discharge part by supplying nitrogen gas to the condensed water discharge part in a state where the connection with the gas phase chamber is interrupted;
A method for producing dissolved nitrogen gas water, comprising: Further comprising the step of measuring the amount of the condensed water introduced into the condensed water discharge part,
In the step of disconnecting the connection between the condensed water discharge part and the gas phase chamber, if the amount of the condensed water introduced into the condensed water discharge part exceeds a predetermined amount, the condensed water discharge part and the gas phase Connection with a chamber is interrupted | blocked, The nitrogen gas dissolved water manufacturing method of Claim 1 characterized by the above-mentioned.   The step of discharging the condensed water includes supplying nitrogen gas to the condensed water discharge portion in a state where the connection with the gas phase chamber is cut off, and reducing the pressure of the condensed water discharge portion, thereby discharging the condensed water. 3. The method for producing dissolved nitrogen gas according to claim 1 or 2, wherein the condensed water introduced into the section is discharged.   The method for producing dissolved nitrogen gas according to claim 3, wherein the condensed water discharge part is decompressed by a vacuum pump.   The method for producing dissolved nitrogen gas according to claim 3, wherein the condensed water discharge part is decompressed by an ejector. A system for producing dissolved nitrogen gas, comprising: a gas dissolution membrane module having a gas phase chamber and a liquid phase chamber partitioned by a gas permeable membrane; and a condensed water discharge device for discharging condensed water generated in the gas phase chamber. Because
The condensed water discharge device is:
A condensed water discharge unit connected to the gas phase chamber, into which condensed water generated in the gas phase chamber is introduced;
A valve capable of blocking connection between the condensed water discharge portion and the gas phase chamber;
A nitrogen gas supply device for supplying nitrogen gas to the condensed water discharge unit;
A system for producing dissolved water of nitrogen gas, comprising: The condensed water discharge device further includes a measuring device for measuring the amount of the condensed water introduced into the condensed water discharge portion,
The valve according to claim 6, wherein when the amount of the condensed water measured by the measuring device exceeds a predetermined amount, the valve cuts off the connection between the condensed water discharge part and the gas phase chamber. Nitrogen gas dissolved water production system.   The nitrogen gas dissolved water production system according to claim 6 or 7, wherein the condensed water discharge device further includes a decompression means for decompressing the condensed water discharge unit.   9. The nitrogen gas dissolved water production system according to claim 8, wherein the decompression means is a vacuum pump.   The system for producing dissolved water of nitrogen gas according to claim 8, wherein the decompression means is an ejector.

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