CN115667094A

CN115667094A - Gas seal tank, seal gas supply method, ultrapure water production apparatus, and ultrapure water production method

Info

Publication number: CN115667094A
Application number: CN202180039357.9A
Authority: CN
Inventors: 山本克美
Original assignee: Nomura Micro Science Co Ltd
Current assignee: Nomura Micro Science Co Ltd
Priority date: 2020-08-20
Filing date: 2021-06-25
Publication date: 2023-01-31
Also published as: JP2022035213A; TW202208254A; KR20230051424A; WO2022038897A1

Abstract

Provided is a gas seal tank capable of suppressing the influence of dynamic pressure when a seal gas is supplied, and efficiently and stably adjusting the pressure of a gas phase portion. The gas-tight tank (10) is provided with: a hermetically sealable container (11) for containing the liquid (50) by bringing the liquid (50) into contact with a gas phase section (60) composed of a sealing gas; a seal gas exhaust device (12) which exhausts the seal gas in the storage container (11) when the pressure of the gas phase part (60) in the storage container (11) is higher than a predetermined exhaust starting pressure; and a seal gas supply device (13) that supplies seal gas to the gas phase section (60) in the storage container (11), wherein the seal gas supply device (13) has a seal gas supply port (13 a), and the seal gas supply port (13 a) is provided such that the supply direction of the seal gas supplied is parallel to or at an acute angle relative to the liquid surface (50 a) of the liquid (50).

Description

Gas seal tank, seal gas supply method, ultrapure water production apparatus, and ultrapure water production method

Technical Field

The present invention relates to a gas seal tank, a seal gas supply method, an ultrapure water production apparatus, and an ultrapure water production method.

Background

In a tank that temporarily stores and stores a liquid, when outside air (air) enters the tank, corrosion of the inner wall of the tank due to internal condensation, mixing of outside air components or moisture into the liquid in the tank, deterioration of the liquid due to oxidation, and the like occur, and therefore, in order to prevent the entry of outside air, replacement of the gas phase portion in the tank with a seal gas (inert gas) is performed.

Such a tank is relatively large, and therefore, the use of the stored liquid decreases, the replenishment of the liquid increases, and the like, and accordingly, the pressure in the gas phase portion changes due to changes in the gas phase portion, the external air conditions of the tank, and the like. Therefore, when the pressure of the gas phase portion increases, the sealing gas is discharged to the outside of the tank to reduce the pressure of the gas phase portion, and when the pressure of the gas phase portion decreases, the sealing gas is supplied.

For example, in the cleaning of precision electronic parts such as semiconductor wafers, ultrapure water is required which dissolves electrolytes, fine particles, colloidal substances, organic polymers, and exothermic substances, and also removes as much as possible dissolved gases, particularly dissolved oxygen, which may promote the growth of microorganisms. In particular, when a semiconductor wafer or the like is cleaned in pure water in which oxygen is dissolved, oxidation of the wafer is promoted, which causes a problem of deterioration in yield. Therefore, a degassing facility such as a vacuum degassing apparatus or a heating degassing apparatus is attached to the production line of pure water. The pure water from which the dissolved gas has been removed by these deaerators is temporarily stored in a pure water tank provided in the production line until the pure water is sent to a next-stage subsystem or until the pure water is used at a point of use. However, although oxygen, carbonic acid gas, and the like are trace in the pure water storage tank, they may be dissolved again in pure water in an amount that is not preferable for cleaning of semiconductor wafers, and a method of sealing the water surface of pure water with an inert gas by pressurizing the inert gas such as nitrogen into the gas phase portion in the pure water storage tank has been generally employed so far (for example, see patent document 1).

Further, as the liquid contained in the gas-tight tank, there are mentioned, in addition to pure water (ultrapure water), oil such as rust preventive oil, hydraulic oil for hydraulic devices, petroleum-based liquid, volatile liquid and the like, and the liquid is contained in the tank by being similarly gas-tight (for example, see patent documents 2 and 3).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. H06-191591

Patent document 2: japanese laid-open patent publication No. 2005-256886

Patent document 3: japanese patent laid-open No. 2007-45491

Disclosure of Invention

Problems to be solved by the invention

However, in the conventional gas seal tank, since the seal gas is supplied at a higher pressure to the gas phase portion of the gas seal tank in which a pressure higher than the normal outside pressure is sealed, the dynamic pressure generated at this time may be a problem.

That is, the seal gas supplied into the gas seal tank is generally supplied downward in the vertical direction from a seal gas supply port provided in a ceiling portion of the gas seal tank. However, since the supplied seal gas collides with the liquid surface of the liquid contained in the gas seal tank and flows while changing its direction to the left and right and upward, the pressure detection unit of the seal gas exhaust device may malfunction due to the dynamic pressure of the seal gas flowing upward. In this malfunction, the pressure detection unit erroneously recognizes the pressure of the gas phase portion in the gas seal tank as a pressure higher than the actual pressure, and therefore, the seal gas is discharged to the outside of the gas seal tank at this time. However, since the dynamic pressure based on the supply of the seal gas is a cause of the operation due to the malfunction, the operation of exhausting the seal gas is not stopped, the pressure of the gas phase portion is lowered, the supply of the seal gas is continued, and the exhaust of the seal gas is continued. That is, even when the amount of liquid in the tank is constant, the exhaust and intake are performed alternately, and this continues continuously, so that the seal gas is unnecessarily consumed.

Accordingly, an object of the present invention is to provide a gas seal tank and a seal gas supply method capable of stably supplying seal gas, which can suppress the influence of dynamic pressure when seal gas is supplied to the gas seal tank and efficiently and stably adjust the pressure of a gas phase portion.

Another object of the present invention is to provide an ultrapure water production apparatus and an ultrapure water production method using the gas seal tank.

Means for solving the problems

The gas seal tank of the present invention is characterized by comprising: a hermetically sealable container for containing a liquid in contact with a gas phase portion formed of a sealing gas; a seal gas exhaust device configured to exhaust the seal gas in the storage container when a pressure of a gas phase portion in the storage container is higher than a predetermined exhaust start pressure; and a seal gas supply device configured to supply a seal gas to a gas phase portion in the storage container, wherein the seal gas supply device has a seal gas supply port provided in such a manner that a supply direction of the seal gas supplied from the seal gas supply port is parallel to or acute in angle with respect to a liquid surface of the liquid.

The method for supplying a sealing gas according to the present invention is characterized in that the sealing gas is supplied by the sealing gas supply means so as to be parallel to or at an acute angle with respect to the liquid surface of the liquid, using the gas sealed tank of the present invention which contains the liquid and whose gas phase portion is filled with the sealing gas.

The ultrapure water production apparatus of the present invention is characterized by comprising a primary pure water apparatus having a degasifier, and a secondary pure water apparatus, wherein the gas seal tank of the present invention is disposed between the primary pure water apparatus and the secondary pure water apparatus, or in the primary pure water apparatus at a stage subsequent to the degasifier.

The method for producing ultrapure water according to the present invention is a method for producing ultrapure water, comprising producing primary pure water obtained by degassing water to be treated in a primary pure water apparatus provided with a degasifier, and treating the primary pure water in a secondary pure water apparatus to produce secondary pure water, wherein the primary pure water obtained by the primary pure water apparatus or the treated water degassed by the degasifier in the primary pure water apparatus is contained in the gas-tight tank of the present invention.

Effects of the invention

According to the gas canister and the method of supplying the sealing gas of the present invention, the pressure in the gas phase portion can be efficiently and stably adjusted while suppressing the influence of dynamic pressure when the sealing gas is supplied.

Further, the gas canister and the method of supplying the sealing gas according to the present invention suppress the blowing of the sealing gas to the liquid surface of the contained liquid at the time of supplying the sealing gas, and therefore, can suppress the fluctuation of the liquid surface, stabilize the liquid surface, and suppress the amount of the sealing gas dissolved in the liquid.

The apparatus and method for producing ultrapure water according to the present invention can stably store primary pure water and efficiently and stably supply secondary pure water to the apparatus for producing ultrapure water, when secondary pure water is produced from the primary pure water produced, because the gas-tight tank according to the present invention is provided therebetween. Furthermore, the contamination of the seal gas into the primary pure water and the like can be suppressed, and the ultrapure water can be produced efficiently and stably.

Drawings

Fig. 1A is a side sectional view showing a schematic configuration of a gas sealing can in the embodiment of the present invention.

Fig. 1B is a plan view showing a schematic configuration of a gas sealing can in the embodiment of the present invention.

Fig. 2A is a diagram for explaining a sealing gas supply direction of the sealing gas supply device in the embodiment of the present invention.

Fig. 2B is a diagram for explaining a sealing gas supply direction of the sealing gas supply device in the embodiment of the present invention.

Fig. 3 is a diagram for explaining a relationship with a liquid surface with respect to a sealing gas supply direction of the sealing gas supply device in the embodiment of the present invention.

Fig. 4 is a plan view showing a modification of the gas sealing can in the embodiment of the present invention.

Fig. 5 is a view for explaining a supply direction of the sealing gas in the gas sealing tank shown in fig. 4.

Fig. 6 is a diagram showing a distance from the seal gas supply device to the pressure detection portion in the gas seal tank shown in fig. 4.

Fig. 7 is a plan view showing a modification of the gas sealing can according to the embodiment of the present invention.

Fig. 8 is a plan view showing a modification of the gas sealing can according to the embodiment of the present invention.

FIG. 9 is a view showing a schematic configuration of an ultrapure water production apparatus according to the present embodiment.

Fig. 10 is a graph showing the temporal change in dissolved nitrogen concentration of ultrapure water obtained by the examples and comparative examples.

Detailed Description

Hereinafter, a gas canister and a method of supplying a sealing gas in the present embodiment will be described with reference to the drawings.

[ gas-tight canister ]

A gas canister according to a first embodiment of the present invention includes: a hermetically sealable container for containing a liquid by bringing the liquid into contact with a gas phase portion formed of a sealing gas; a sealed gas exhaust device for exhausting the sealed gas in the container when the liquid is supplied from the liquid supply port and the pressure of the gas phase part in the container is higher than a predetermined exhaust start pressure; and a seal gas supply device for supplying seal gas to the gas phase portion in the housing container when the liquid flows out from the liquid outlet and the pressure of the gas phase portion in the housing container is lower than a predetermined supply start pressure. In the gas canister, the seal gas supply device has a seal gas supply port provided in such a manner that the supply direction of the seal gas supplied is parallel to or at an acute angle with respect to the liquid surface of the liquid. In addition, illustration of the liquid supply port and the liquid outflow port is omitted.

As an example of the gas sealed tank, as shown in fig. 1A and 1B, a gas sealed tank 10 having a storage container 11, a seal gas supply device 12, and a seal gas exhaust device 13 can be exemplified. Hereinafter, each configuration will be described in further detail.

The storage container 11 is a container that can hermetically seal and store the liquid 50 to be stored. At this time, the storage container 11 can store the liquid 50 by bringing the liquid 50 into contact with the gas phase portion 60 made of the sealing gas. The sealing gas can prevent the liquid 50 from coming into contact with air or the like, and can suppress deterioration (oxidation or the like) thereof. In addition, since the sealed gas is generally stored in a pressurized state at a higher pressure than normal pressure, a storage container having resistance to the pressure of the sealed gas to be held is used as the storage container 11.

The storage container 11 may stably store the liquid 50 as described above, and the shape thereof is not particularly limited. As the storage container 11, a known shape of the storage container can be exemplified, and for example, a shape of the storage container whose external shape in plan view is a polygonal shape such as a circular shape, a triangular shape, or a quadrangular shape, and a circular shape is preferable. Fig. 1B illustrates a case where the outer shape of the storage container 11 is a circular shape. Here, the circular shape includes not only a perfect circle but also a flat ellipse, a deformed shape in which a part of the circle has a concavity and a convexity, and the like, and the polygonal shape also includes the deformed shape.

The size of the storage container 11 is not particularly limited, and may be set as appropriate according to the type of the liquid 50 to be stored and the storage (use) state thereof. For example, when ultrapure water used for cleaning in the production of semiconductor devices is used, one side (diameter) of the storage container can be set to 1 to 10m, and the height (side wall) can be set to 1 to 12m.

The liquid 50 contained in the storage container 11 is not particularly limited as long as it is required to be isolated from the outside air such as air, and known liquids can be exemplified. Specific examples of such a liquid include pure water (ultrapure water), engine oil such as lubricating oil and rust-proof oil, petroleum-based liquid, and chemical liquid, and pure water (ultrapure water) is preferable.

As the sealing gas constituting the gas phase section 60, a rare gas such as nitrogen, helium, neon, or argon is generally used as an inert gas, and a known inert gas can be used without limitation. The sealing gas may be selected as appropriate to be optimal. One kind of sealing gas may be used alone, or two or more kinds may be used in combination.

The seal gas exhaust device 12 is a device for exhausting the seal gas in the storage container 11 when the pressure of the gas phase portion 60 in the storage container 11 is higher than a predetermined exhaust start pressure.

When the pressure of the gas phase portion 60 in the housing container 11 becomes high, the seal gas exhaust device 12 exhausts the seal gas constituting the gas phase portion 60 to the outside of the housing container 11, so that the pressure in the housing container 11 does not become excessively high.

As the seal gas exhaust device 12, a known seal gas exhaust device can be used without limitation, and examples thereof include a bleed valve, an automatic control valve, and the like. Specifically, the KN series available from King Kogyo K.K. is exemplified.

The sealing gas supply device 13 is a device for supplying the sealing gas to the gas phase portion 60 in the storage container 11. The seal gas supply device 13 has a seal gas supply port 13a, and the seal gas supply port 13a is provided so that the supply direction of the supplied seal gas is parallel to or at an acute angle with respect to the liquid surface of the contained liquid 50.

The seal gas supply device 13 includes a gas tank (not shown) for storing seal gas, and the gas tank is connected to a pipe 13b, is adjusted to a predetermined pressure by a pressure reducing valve (not shown), and is capable of introducing the seal gas into the storage container 11 through the pipe 13 b.

The pipe 13b has a valve 13c for controlling the flow of the seal gas, and the seal gas is supplied into the storage container 11 by opening the valve 13 c. The valve 13c is normally opened and closed when the pressure of the gas phase portion 60 in the storage container 11 is lower than a predetermined supply start pressure, and is closed when the pressure of the gas phase portion 60 is higher than the supply start pressure. Thus, in this case, the seal gas supply device 13 has a pressure detection portion for gas supply for detecting the pressure of the gas phase portion 60.

As the seal gas supply device 13, a gas seal unit GU series manufactured by seiko corporation, and the like are suitably used. Further, the present invention is not limited to this, and a device in which a normal pressure sensor is combined with an automatic control valve may be used.

The seal gas supply device 13 is characterized by having a seal gas supply port 13a provided so that the supply direction of the seal gas to be supplied is parallel to or at an acute angle with respect to the liquid surface of the liquid 50 to be stored. This point will be described with reference to fig. 2A and 2B.

Fig. 2A and 2B show a case where the pipe extends vertically downward from the ceiling of the storage container 11, but the gas supply port 13a is provided on a side surface of the pipe near an end portion of the pipe. In a typical conventionally known seal gas supply device, the seal gas is directly opened at an end of the pipe, and the seal gas is blown vertically to the liquid 50, which is different from the present invention.

In the sealing gas supply device 13, the supply direction of the sealing gas may be set to the predetermined direction, and for example, as shown in fig. 2A and 2B, the sealing gas supply device may be exemplified in the vicinity of an end portion of a pipe extending downward in the vertical direction from the ceiling of the storage container 11, and a gas supply port 13a may be provided in a side surface of the pipe.

Fig. 2A shows an example in which a disk-shaped member is provided at an end (lower end) of a pipe, and a seal gas supply port 13a is provided in a side surface near the end of the pipe. At this time, the supplied seal gas is introduced into the housing container 11 from above through the pipe, but at this time, the supplied seal gas collides with the disk-shaped member at the end portion, passes through the seal gas supply port 13a, and is supplied in the horizontal direction. That is, the supply direction FD of the sealing gas at this time is parallel to the liquid surface 50 a.

Fig. 2B shows an example in which an elliptic plate-like member is obliquely provided at an end (lower end) of the pipe, and the side surface near the end of the pipe is provided with the seal gas supply port 13a in the same manner as in fig. 2A. At this time, the supplied seal gas is introduced into the storage container 11 from above through the pipe, but at this time, the seal gas collides with the elliptical plate-shaped member at the end portion, passes through the seal gas supply port 13a, and is supplied obliquely downward. That is, the supply direction FD of the sealing gas at this time is acute angle with respect to the liquid surface 50 a. The shape of the seal gas supply port 13a is not particularly limited as long as the shape does not depart from the gist of the present invention. For example, a pipe bent in an L shape can be used.

The sealing gas supply device 13 illustrated in fig. 2A is an example having a pipe shape in which the flow of the sealing gas is changed from the vertical direction to the horizontal direction, but the supply direction FD of the sealing gas is further described with reference to fig. 3.

The angle of the feeding direction FD with respect to the liquid surface 50a can be represented by an angle θ shown in fig. 3. The supply direction FD is an acute angle with respect to the liquid surface 50a, and in the present specification, means that the angle θ is an angle smaller than 90 degrees, and the angle θ is preferably 45 degrees or less, more preferably 30 degrees or less, further preferably 20 degrees or less, and particularly preferably 10 degrees or less. When the angle θ is 0, the feeding direction FD is most preferably parallel to the liquid surface 50 a.

When the seal gas is supplied at an acute angle with respect to the liquid surface 50a in this manner, the dynamic pressure due to collision between the seal gas and the liquid surface 50a is reduced, and erroneous operation of the seal gas exhaust device 12 can be suppressed.

In addition, although the above description has exemplified a pipe shape in which the flow of the seal gas is changed from the vertical direction to the horizontal direction, the seal gas may be supplied directly parallel to or at an acute angle with respect to the liquid surface 50a without changing the supply direction in a case where the pipe 13b for supplying the seal gas to the side surface of the housing container 11 is connected and the connection portion is directly provided as the supply port 13a.

While the vertical direction has been described above with respect to the supply direction FD of the seal gas, the positional relationship between the seal gas exhaust device 12 and the supply direction in a plan view of the gas seal tank 1 will be described below.

Since the dynamic pressure due to collision between the sealing gas and the liquid surface 50a can be reduced in the direction FD of supply of the sealing gas as described above, the direction FD of supply of the sealing gas in a plan view is not particularly limited, and the sealing gas can be supplied in any direction. In this case, the seal gas supply port 13a may be provided over the entire 360 degrees in the planar direction, but as shown in fig. 2A and 2B, it is preferable to provide a side wall in a part thereof and provide the seal gas supply port 13a in a specific direction.

In order to suppress the malfunction of the above-described exhaust operation of the seal gas, the supply direction FD is preferably set as follows.

Fig. 4 and 5 are views showing the gas sealing can 10 in plan view, as in fig. 1B. Here, the seal gas exhaust device 12 detects the pressure of the gas phase portion 60 as described above, and determines whether or not the operation is possible, and therefore, includes a pressure detector. The pressure detector is configured such that an opening for detection, which is indicated as a pressure detection portion 12a, is provided in the vicinity of the sealed gas exhaust device 12, and the opening is connected to the pressure detector via a gas flow path.

The position of the pressure detecting unit 12a is not particularly limited as long as the pressure of the gas phase unit 60 can be detected, but in the present invention, it is preferable that the pressure detecting unit is not affected by the supply and exhaust of the seal gas. Therefore, fig. 4 and 5 illustrate a case where the pressure detection unit 12a is provided at a position slightly separated from the connection portion (opening through which the seal gas passes during the gas discharge) between the seal gas discharge device 12 and the housing container 11.

At this time, the seal gas supply port 13a is preferably not opened to the pressure detection unit 12a that operates the seal gas exhaust device 12. Here, "not to open to the side of the pressure detection unit 12 a" means that the sealing gas is not directly supplied from the sealing gas supply port 13a to the lower side of the pressure detection unit 12a, and in this case, the pressure detection unit 12a can accurately detect the pressure of the gas phase unit 60 without being affected by the pressure of the supplied sealing gas.

In fig. 4, the supply direction FD of the sealing gas is shown, but this indicates the main supply direction, and since the opening has a width in practice, the sealing gas is supplied so as to spread in a fan shape to the left and right of the supply direction FD shown in fig. 4. That is, it is preferable that all the supply directions FD are not directed toward the pressure detection unit 12a.

Further, it is preferable that the seal gas supply port 13a is not opened to the seal gas exhaust device 12 side other than the pressure detection unit 12a side.

Fig. 5 is a diagram for explaining a range of the supply direction FD of the sealing gas, which is preferable in a plan view. At this time, it is preferable that the seal gas supply port 13a is provided on a concentric circle passing through the seal gas supply port 13a with respect to the outer shape of the housing container 11 so that the supply direction FD of the seal gas ranges from the tangential direction of the concentric circle starting from the seal gas supply port 13a to the center position of the concentric circle. A preferred region Q in the direction FD of the sealing gas supply at this time is shown by a hatched pattern.

In addition to the above-described effects, the sealing gas does not collide with the side wall of the storage container 11 immediately after the supply, or even if the sealing gas collides with the side wall, the angle formed between the supply direction and the side wall is an acute angle of 45 degrees or less, and therefore, there is no problem such as occurrence of turbulence.

Further, since the sealing gas is supplied in the direction FD in many cases so as to have a fan-like spread as described above, the portion overlapping the range of the region Q in the direction FD is preferably 50% or more, more preferably 80% or more, still more preferably 90% or more, particularly preferably 95% or more, and most preferably 100%.

The seal gas supply port 13a is preferably disposed such that the seal gas supply port 13a is not visible when the piping of the seal gas supply device 13 is viewed from the position of the pressure detection unit 12a. Thus, the supplied seal gas easily flows along the side surface of the storage container 11, and a swirling flow is easily generated in the storage container 11. By providing the swirling flow, for example, when the tank is filled with air at the time of starting the water purification apparatus or when air is mixed in, the water can be easily discharged and replaced.

In addition, when the swirling flow is set, it is preferable that the pressure detection unit 12a is provided near the back surface of the seal gas supply device 13, so that the movement distance of the supplied seal gas flow when reaching the pressure detection unit 12a can be increased, and the pressure detection unit 12a is not affected by the supply pressure of the seal gas. For example, as shown in fig. 6, the distance between the seal gas supply device 13 and the pressure detection unit 12a is represented by a distance a in a straight line, but the moving distance in which the flow of the seal gas supplied in the direction of the arrow whirls and reaches the pressure detection unit 12a is, for example, at least a distance b represented by a broken line. Therefore, the distance between the seal gas supply device 13 and the pressure detection unit 12a can be made closer, and the closer the distance is, the longer the seal gas reaches below the pressure detection unit after being supplied, and the more difficult the seal gas is affected by the dynamic pressure of the supplied seal gas. For example, since the distance between the seal gas supply port 13a of the seal gas supply device 13 and the pressure detection unit 12a can be made close to within 1m, the degree of freedom in installing the tank, the piping, and the attached equipment becomes large, and the device design becomes easy. In fig. 6, the distance between the seal gas supply device 13 and the pressure detection unit 12a is taken as a problem, but the distance between the seal gas supply device 13 and the seal gas exhaust device 12 can be considered in the same manner.

The sealing gas supply device 13, the sealing gas exhaust device 12, and the pressure detection unit 12a may be provided in plurality as necessary.

When a plurality of sealing gas supply ports are provided, for example, the sealing gas supply port 13a may be directed toward the center of the circle as shown in fig. 7, or the sealing gas supply device 13, the sealing gas exhaust device 12, and the pressure detection unit 12a may be provided diagonally as shown in fig. 8. In the case of the arrangement as shown in fig. 8, the sealing gas is more preferably likely to flow along the side surface of the storage container 11, and a swirling flow is more likely to be generated in the storage container 11.

Note that, in the case where a cylindrical member is used as shown in fig. 2A and 2B, the seal gas supply port 13a of the seal gas supply device 13 described above may be a movable member that can rotate around its axis. In this case, in the case where the seal gas supply port 13a is provided on the side wall in the planar direction, the direction of the seal gas supply port 13a can be changed by rotation. In this case, it is not necessary to pay attention to the arrangement direction of the seal gas supply device 13, and it is preferable that the optimum supply direction FD of the seal gas can be adjusted according to the arrangement of the seal gas exhaust device 12, the pressure detector 12a thereof, and the like. For example, the influence of the sealing gas supply direction may be complicated. This possibility is high when a plurality of seal gas supply devices 13, seal gas exhaust devices 12, and pressure detection units 12a are provided. Therefore, in the use of the gas seal tank, the optimum direction FD of the seal gas can be adjusted while confirming the actual influence.

[ method of supplying sealing gas ]

Next, a method of supplying the seal gas according to the present invention will be described by taking a case of using the gas seal tank of fig. 1A and 1B as an example.

First, the gas-tight tank 10 is prepared which contains the liquid 50 in the container 11 and fills the gas phase portion 60 with the sealing gas, and then the liquid flows out from the liquid outlet port, and when the pressure of the gas phase portion in the container is lower than a predetermined supply start pressure, the sealing gas is supplied by the sealing gas supply device 13 so as to be parallel to or at an acute angle with respect to the liquid surface 50a of the liquid 50.

By supplying the sealing gas based on the specific conditions in this manner, the sealing gas does not directly collide with the liquid surface 50a of the liquid 50 from the vertically upward direction, and the dynamic pressure due to the supply of the sealing gas can be suppressed, whereby the malfunction of the sealing gas exhaust apparatus can be avoided.

Further, since the seal gas does not directly collide with the liquid surface 50a of the liquid 50 from above in the vertical direction, the fluctuation of the liquid surface 50a can also be suppressed. In this case, since the fluctuation of the liquid surface 50a is suppressed, the height of the liquid surface 50a is accurately measured by the liquid level meter or the like, and the measured value does not pulsate. Therefore, since the liquid level of the liquid 50 can be stably measured, when the liquid level is proportionally controlled, the control accuracy can be improved and the liquid level can be stably controlled. For example, when the pump is controlled by the height of the liquid surface 50a, the pump is not turned on or off in a fragmentary manner due to pulsation of the liquid surface 50 a.

Further, since the seal gas does not directly collide with the liquid surface 50a of the liquid 50 from above in the vertical direction, the seal gas can be prevented from being mixed (dissolved) into the liquid 50.

Hereinafter, the storage of the liquid in the storage container, the replacement of the liquid in the seal gas, the supply of the seal gas, and the exhaust will be described in more detail.

A gas airtight can 10 is prepared. At this time, the liquid 50 is not stored in the storage container 11, and the sealing gas is not supplied and filled with air. In the gas seal tank 10, first, the liquid 50 is supplied, and a part of the air is replaced with the liquid 50. After that, the liquid 50 is discharged from the liquid discharge port, and the sealing gas is supplied. At this time, the supply start pressure of the seal gas is set to a predetermined pressure range of the exhaust start pressure. By repeating the operations of supplying the liquid (discharging the air) and supplying the sealing gas, only the liquid 50 and the gas phase filled with the sealing gas are formed in the storage container 11. In this case, according to the method of the present embodiment, since air cannot be accumulated in any portion in the tank and air can be efficiently discharged, the number of repetitions of the above operation can be reduced and the start-up can be performed at an early stage.

The storage container 11 is provided with flow paths (not shown) for supplying and discharging the liquid 50.

When the gas phase portion 60 is replaced with the seal gas and the liquid 50 is supplied to a predetermined water level, the operation of storing the liquid in the storage container, which is the object of the present invention, can be performed. That is, the liquid 50 supplied to the predetermined water level maintains its state until the liquid 50 is used.

Then, when the use of the liquid 50 is started, the liquid 50 in the storage container 11 decreases, and the volume of the gas phase portion 60 increases, so that the pressure of the gas phase portion 60 decreases. When the pressure of the gas phase portion 60 is lower than a predetermined supply start pressure, the seal gas supply device 13 is operated to supply the seal gas into the storage container 11, thereby adjusting the pressure of the gas phase portion 60.

At this time, the sealing gas is stably supplied as described above because the supply direction thereof is parallel to or at an acute angle with respect to the liquid surface 50 a.

Next, when the water level of the liquid 50 is lowered to a predetermined amount or less by use, the liquid 50 is supplied into the storage container 11 again to a desired amount. At this time, when the liquid 50 is supplied, the gas phase portion 60 is compressed and the pressure becomes high, but when the pressure becomes higher than a predetermined exhaust start pressure, the seal gas exhaust device 12 operates to discharge the seal gas to the outside of the housing container 11, thereby adjusting the pressure of the gas phase portion 60.

When the liquid 50 is supplied to a desired amount, the supply of the liquid 50 is stopped, and the pressure fluctuation of the gas phase portion 60 is also eliminated, and therefore, the operation of the seal gas exhaust apparatus 12 is also stopped. At this time, the liquid 50 is in contact with the sealing gas constituting the gas phase portion 60, and is not in contact with air or the like, and therefore, can be stably stored.

The supply start pressure and the exhaust start pressure are appropriately set so that the storage state of the liquid 50 is optimal, and the exhaust start pressure is set to be higher than the supply start pressure (exhaust start pressure > supply start pressure), and are not particularly limited.

For example, when the liquid 50 is ultrapure water used for cleaning in semiconductor device production, the supply start pressure is set to 0.2 to 1kPa, the exhaust start pressure is set to 0.5 to 5kPa, and the supply pressure of the seal gas is set to 0.2 to 0.5MPa, and the exhaust start pressure is set to about 0.3 to 2kPa higher than the supply start pressure. The numerical values are merely examples, and are not necessarily limited thereto.

At this time, the pressure of the gas phase portion 60 is adjusted to be maintained in a range from the supply start pressure to the exhaust start pressure. In the case where the seal gas supply device 13 uses an automatic control valve together with the seal gas exhaust device 12, pressure ranges are set as the supply pressure and the exhaust pressure. For example, the supply pressure is set to 0.2 to 0.5kPa, the exhaust pressure is set to 1 to 5kPa, and the pressure of the gas phase section 60 is maintained between the set pressures, for example, in the range of 0.5 to 1 kPa.

Next, an embodiment in which the gas seal tank and the method of supplying a seal gas are applied to an ultrapure water production system will be described.

(apparatus for producing ultrapure water)

As shown in fig. 9, the ultrapure water production apparatus of the present embodiment is an ultrapure water production apparatus 30 having a primary pure water apparatus 31 and a secondary pure water apparatus 32 of a degasser, and having the configuration in which the gas seal tank 10 of the present embodiment described above is provided between the primary pure water apparatus 31 and the secondary pure water apparatus 32.

The primary water purification apparatus 31 and the secondary water purification apparatus 32 can be any apparatuses used in known ultrapure water production apparatuses without any particular limitation. Further, the primary pure water apparatus 31 is provided with a degasifier.

In fig. 9, the gas seal tank 10 is configured to store the primary pure water obtained by the primary pure water apparatus 31, but the gas seal tank may be incorporated into the primary pure water apparatus 31 and used as a storage tank constituting the primary pure water apparatus 31. At this time, the gas seal tank 10 is disposed at a position located at a later stage than the degasifier, and stores the treated water to be degassed.

The degasifier used here may be a known degasifier, and preferably a degassing membrane, a vacuum degassing tower, or a catalyst degasifier.

Further, as other devices constituting the primary water purification device 31, a reverse osmosis membrane device, an electron deionization device, an ion exchange device, an ultraviolet irradiation device, and the like can be mentioned, and these devices can be provided in any combination.

The secondary pure water apparatus also preferably includes a degasser. The degasifier may be a known degasifier, like the primary water purifier, and preferably includes a degassing membrane, a vacuum degassing tower, and a catalyst degasifier. Examples of other devices constituting the secondary water purification apparatus include an ultraviolet irradiation apparatus, an ultrafiltration apparatus, and an ion exchange apparatus, and these devices can be provided in any combination.

Further, the ultrapure water to be produced may be provided with a dissolving film and a dissolving tank to dissolve a gas such as hydrogen, ozone, or nitrogen, thereby producing functional water. In this case, since ultrapure water having low dissolved nitrogen is used, the amount of gas dissolved as the functional water can be increased, and thus, high-concentration functional water can be produced. Further, since ultrapure water with little fluctuation in dissolved nitrogen concentration is used, the gas concentration of the functional water can be stabilized.

In a degasser, nitrogen is generally used as a purge gas in a degassing membrane or a vacuum degassing tower, and therefore the removal rate of nitrogen in the treated water after the degassing treatment does not increase. In addition, the catalyst degasser has a disadvantage that nitrogen cannot be removed. In such degassed treated water, although nitrogen may be further dissolved in the conventional gas sealed tank, the disadvantages of the conventional gas sealed tank can be compensated for by the apparatus and method for producing pure water using the gas sealed tank of the present embodiment.

In this ultrapure water production apparatus 30, the gas seal tank 10 of the present embodiment is used as a tank for storing primary ultrapure water, and ultrapure water can be produced by the same operation as in the production of conventional ultrapure water. That is, the water to be treated is degassed in the primary pure water apparatus 31 having a degasser to obtain primary pure water, and the primary pure water is stored and stored in the gas seal tank 10. Next, the primary pure water is sent from the gas seal tank 10 to the secondary pure water apparatus 32 at a desired timing, and is treated in the secondary pure water apparatus 32 to obtain secondary pure water (ultrapure water). The produced ultrapure water may be sent to a place of use (POU), and for example, the remaining ultrapure water may be circulated through a gas seal tank. Here, the liquid contained in the gas seal tank 10 is primary pure water, and nitrogen is used as its seal gas.

In the case of this ultrapure water production system 30, since the gas seal tank 10 of the present embodiment is used, the amount of nitrogen used can be reduced as compared with the conventional one.

Further, since the water surface in the gas seal tank 10 is not disturbed by the direct impact of the gas flow (nitrogen flow), the amount of dissolved nitrogen in the tank can be minimized. This is because the area of the interface between the dissolved liquid and the gas is minimized because the water level in the tank is not disturbed. The degassed primary pure water stored in the tank is so-called freely soluble water (Hungrywater), and nitrogen is rapidly dissolved from the gas-liquid interface, and therefore the above-described effect is exhibited without disturbing the reduction in surface area by the water surface.

In the past, in an ultrapure water production apparatus, although the design conditions and the operating conditions of the apparatus such as a gas seal tank and a degasser are also based, the amount of Dissolved Nitrogen (DN) in the produced ultrapure water is high and fluctuates greatly due to the dissolution of nitrogen in the tank. For example, although the average concentration may vary from 0.5ppm to 1.5ppm, the average concentration may be 0.4ppm, or 0.3 to 0.5ppm, and the average concentration and variation may be small when the ultrapure water production apparatus of the present embodiment is used.

[ examples ] A method for producing a compound

The present invention will be described below with reference to examples. This embodiment is an example, and the present invention is not limited to the description of this embodiment.

(example 1)

The apparatus having the configuration shown in fig. 9 was used as an ultrapure water production apparatus. Here, the primary pure water apparatus 31 is configured such that an activated carbon Apparatus (AC), a reverse osmosis membrane apparatus (RO), an electrodeionization apparatus (EDI), an ultraviolet irradiation apparatus (TOC-UV), a mixed bed ion exchange apparatus (MB), and a degassing membrane apparatus (MDG) are connected in this order from the upstream side, and primary pure water obtained from these primary pure water apparatuses is temporarily stored in the gas seal tank 10. The secondary pure water apparatus is disposed at the rear stage of the gas seal tank 10, and is connected with an ultraviolet irradiation apparatus (TOC-UV), a degassing membrane apparatus (MDG), a polishing Machine (MBP), and an ultrafiltration membrane apparatus (UF) in this order from the upstream, and can supply ultrapure water to a place of use (POU).

The gas-tight canister used here has an inner diameter: as shown in fig. 6, a sealed gas exhaust device 12, a pressure detection unit 12a, and a sealed gas supply device 13 are provided on a ceiling portion of a cylindrical sidewall 3900mm and 2500mm in height. A relief valve (trade name: KN1-40JF, manufactured by King Kogyo Co., ltd.) was used as the seal gas exhaust device 12, and a gas seal unit (trade name: GU25, manufactured by King Kogyo Co., ltd.) was used as the seal gas supply device 13. As the seal gas supply device 13, a device having a seal gas supply port 13a in the seal gas supply direction FD shown in fig. 2A and 4 is used. Liqui-CelX4014 (manufactured by 3M) was used as a membrane degasser.

Using this ultrapure water production apparatus, the city water of thickwood was used as the raw water, and the outlet flow rate of the gas seal tank was 300m ³ The ultrapure water was continuously produced by treating raw water. At this time, the seal gas exhaust device 12 is not affected by the dynamic pressure supplied by the seal gas, and its operation is stable. The concentration of dissolved nitrogen in the ultrapure water obtained by the treatment was measured at the outlet of the secondary pure water unit (outlet of the ultrafiltration membrane unit) using a concentration measuring apparatus (product name: oribishphere 510, manufactured by hashes corporation), and the results are shown in FIG. 10.

Comparative example 1

Ultrapure water was produced by the same operation using an ultrapure water production apparatus having the same configuration except that in the ultrapure water production apparatus used in example 1 described above, a conventional gas seal tank (the seal gas supply port of the seal gas supply unit 13 was set to supply seal gas downward in the vertical direction) was used in place of the gas seal tank 10. The dissolved nitrogen concentration of ultrapure water was measured in the same manner as in example 1, and the results are also shown in fig. 10.

Fig. 10 shows the relationship between the elapsed time (h) from the start of measurement of the dissolved nitrogen concentration and the dissolved nitrogen concentration (ppm) of the produced ultrapure water. From the results, it was found that the concentration of dissolved nitrogen in ultrapure water produced by the ultrapure water production apparatus using the gas seal tank of the present embodiment can be reduced to an average of 0.4ppm, and that the fluctuation of the concentration is small, and stable water quality can be obtained.

When the ultrapure water production apparatus of the present embodiment is used, ultrapure water having a low dissolved oxygen content and a low dissolved nitrogen content can be produced, and therefore, ultrapure water for use in, for example, semiconductor display panel production, in particular, ultrapure water for use in a liquid immersion exposure step in semiconductor production can be supplied without requiring any special addition of an apparatus or the like.

As described above, according to the sealing gas supply device and the supply method of the present invention, the sealing gas in the gas sealing tank can be stably supplied.

As described with reference to fig. 4 and 5, the sealing gas can be supplied more stably by setting the positional relationship with the pressure detecting portion 12a of the sealing gas exhaust device 12, the positional relationship with the sealing gas exhaust device 12, the supply direction FD of the sealing gas, and the like.

By applying such a gas sealing tank to an ultrapure water production apparatus, dissolution of the sealing gas (nitrogen gas) into ultrapure water can be suppressed, and ultrapure water with a small amount of dissolved gas or the like reduced can be produced and supplied.

The present invention has been described in terms of several embodiments, which are disclosed as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in other various ways, and various omissions, substitutions, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

Description of reference numerals

10 … gas seal tank, 11 … storage container, 12 … seal gas exhaust device, 12a … pressure detection section, 13 … seal gas supply device, 13a … seal gas supply port, 13b … piping, 13c … valve, 30 … ultrapure water production device, 31 … primary deionized water device, 32 … secondary deionized water device, 50 … liquid, 50a … liquid level, 60 … gas phase section

Claims

1. A gas-tight can, comprising:

a hermetically sealable container for containing a liquid in contact with a gas phase portion formed of a sealing gas;

a seal gas exhaust device configured to exhaust the seal gas in the storage container when a pressure of a gas phase portion in the storage container is higher than a predetermined exhaust start pressure; and

a sealing gas supply device for supplying a sealing gas to the gas phase portion in the container,

in the gas-tight tank, the gas is introduced into the tank,

the seal gas supply device has a seal gas supply port provided so that the supply direction of the seal gas supplied from the seal gas supply port is parallel to or acute in angle to the liquid surface of the liquid.

2. The gas-tight can of claim 1,

the seal gas supply port is not opened to the pressure detection unit side that operates the seal gas exhaust device in a plan view.

3. The gas-tight can of claim 2,

the seal gas supply port is further not open to the seal gas exhaust device side.

4. The gas-tight can according to any one of claims 1 to 3,

the gas sealing tank has a circular outer shape in plan view, and the seal gas supply port is provided on a concentric circle passing through the seal gas supply port with respect to the circular outer shape so that the supply direction of the seal gas ranges from a tangential direction of the concentric circle starting from the seal gas supply port to a center position of the concentric circle.

5. The gas-tight can according to any one of claims 1 to 4,

the seal gas supply port has a piping shape that changes the flow of the seal gas from the vertical direction to the horizontal direction.

6. The gas-tight can according to any one of claims 1 to 5,

the seal gas supply port is provided so as to generate a swirling flow in the gas seal tank by the seal gas supplied thereto.

7. The gas-tight can according to any one of claims 1 to 6,

the sealing gas supply device includes a cylindrical member having the supply port on a side surface thereof, and the cylindrical member is a movable member capable of changing a supply direction of the sealing gas by rotating an axis thereof.

8. A method for supplying a sealing gas,

a gas-tight can according to any one of claims 1 to 7, which contains a liquid and has a gas phase portion filled with a sealing gas,

the sealing gas is supplied by the sealing gas supply device so as to be parallel to or at an acute angle with respect to the liquid surface of the liquid.

9. The sealing gas supply method according to claim 8,

and supplying the seal gas to the gas phase section by the seal gas supply device when the pressure of the gas phase section is lower than a predetermined supply start pressure.

10. The sealing gas supply method according to claim 8 or 9,

when the pressure of the gas phase portion is higher than a predetermined exhaust start pressure, the seal gas is discharged to the outside of the storage container by the seal gas exhaust device.

11. An apparatus for producing ultrapure water, characterized in that,

comprises a primary water purification device having a degasifier and a secondary water purification device,

in the ultrapure water manufacturing apparatus, the ultrapure water is supplied to the ultrapure water manufacturing apparatus,

a gas seal tank according to any one of claims 1 to 7, which is provided between the primary water purification apparatus and the secondary water purification apparatus or at a rear stage of the degasifier in the primary water purification apparatus.

12. A method for producing ultrapure water, characterized in that,

primary pure water obtained by degassing water to be treated in a primary pure water apparatus provided with a degasser,

the primary pure water is processed by a secondary pure water apparatus to produce secondary pure water,

in the method for producing ultrapure water, in the present invention,

the gas seal tank according to any one of claims 1 to 7 contains primary pure water obtained by the primary pure water apparatus or treated water degassed by the degasser in the primary pure water apparatus.