Inert gas sealed water tank

Abstract

To provide an inert gas sealed water tank that reduces a possibility of damage due to earthquakes, and improves maintenance safety and workability.SOLUTION: An inert gas sealed water tank 1 includes a sealed water tank body 2, and a water tank inlet nozzle 3 and a circulating water inlet nozzle 4 attached to a side of the sealed water tank body 2. The water tank inlet nozzle 3 and the circulating water inlet nozzle 4 are connected to water tank inlet piping 3A and circulating water inlet piping 4A having expansion joints 3B and 4B, respectively, and the water tank inlet piping 3A and the circulating water inlet piping 4A have expansion joints 3B and 4B, respectively. Further, a water tank outlet nozzle 6 is attached to a side of the sealed water tank body 2, and the water tank outlet nozzle 6 is connected to water tank outlet piping 6A having an expansion joint 6B. A top of the sealed water tank body 2 is connected to nitrogen gas sealed piping 8 communicating with a nitrogen gas source 8A.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an inert gas sealed water tank sealed with an inert gas such as nitrogen gas for temporarily storing degassed pure water or ultrapure water.

Background Art

[0002] Conventionally, ultrapure water used in the electronic industry field such as semiconductors and pure water for semiconductor cleaning is produced by treating pre-treated raw water with a primary pure water device or further treating it with an ultrapure water production device equipped with a secondary pure water device (subsystem). In such a primary pure water device, it is required to remove dissolved electrolytes, fine particles, colloidal substances, high molecular weight organic substances, heat generating substances, and further dissolved gases, particularly dissolved oxygen, from the raw water as much as possible. For example, when a semiconductor wafer or the like is washed with pure water in which oxygen is dissolved, oxidation of the wafer is promoted and the yield deteriorates. Therefore, a degassing facility such as a membrane type degassing device is attached to the primary pure water device. The pure water from which the dissolved gas has been removed by these degassing facilities is temporarily stored in a water tank for storing pure water provided in the line until it is sent to the next stage subsystem or until it is used at the use point. However, although trace amounts of oxygen, carbon dioxide gas, etc. are present in this water tank, there is a risk of redissolving in the pure water. Therefore, it is generally adopted to press an inert gas such as nitrogen gas into the pure water tank and seal the water surface of the pure water with the inert gas.

[0003] An example of such a conventional inert gas seal tank is shown in Figure 3. In Figure 3, the inert gas seal tank 21 has a cylindrical, sealable seal tank body 22, a tank inlet pipe 23 and a circulating water pipe 24 inserted from the top of the seal tank body 22, and the tank inlet pipe 23 and the circulating water pipe 24 extend from the top of the inert gas seal tank 21 to the bottom of the inert gas seal tank 21 so that they are submerged in the pure water W in which the tank inlet pipe 23 is stored, thereby preventing the pure water injected from the tank inlet pipe 23 and the circulating water pipe 24 from hitting the liquid surface of the pure water W stored in the seal tank body 22. In addition, a nitrogen gas seal pipe 25 connected to a nitrogen gas source 25A, a nitrogen gas pilot pipe 26 connected to a pressure detection means 26A, and a vent pipe 27 connected to the external environment 27A in an openable and closable manner are connected to the top of the seal tank body 22. Meanwhile, on the side of the sealed water tank body 22, an overflow pipe 28 is connected to a nitrogen gas seal pot 28A, with an expansion joint 28B installed in the middle. The water tank outlet nozzle 28 and a spare nozzle 29 are also connected. Furthermore, the water tank inlet pipe 23 and the circulating water pipe 24 are equipped with expansion joints 23A and 24A, respectively, to reduce vibrations caused by earthquakes and other events. Note that 31A, 31B, and 31C are spare pipes.

[0004] In the inert gas seal tank 21 described above, deaerated pure water W is supplied to the seal tank body 22 from the tank inlet pipe 23 and stored. Nitrogen gas supplied from the nitrogen gas source 25A as an inert gas is injected into the space above the surface of the stored pure water W through the nitrogen gas seal pipe 25, thereby expelling existing air and preventing oxygen and carbon dioxide from redissolving into the pure water W within the inert gas seal tank 21. The pure water W in the inert gas seal tank 21 is then sent from a pure water discharge pipe (not shown) connected to the tank outlet nozzle 28 to a subsystem consisting of a use point, an ultraviolet sterilization device, a cartridge polisher, an ultrafiltration membrane device, etc. Unused pure water W is returned through the circulating water pipe 24 as needed. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] In this inert gas-sealed water tank 21, the water tank inlet pipe 23 and the circulating water pipe 24 are inserted from the top surface of the sealed water tank body 22. Therefore, when operating the valve flow rate adjustment or performing maintenance, it is necessary to access the top of the sealed water tank body (tank) 22. This is at a height, which poses a safety problem in the workplace and leaves room for improvement in terms of workability. Furthermore, although expansion joints 23A and 24A are provided in the water tank inlet pipe 23 and the circulating water pipe 24, allowing for some damping of vibrations even in the event of an earthquake, if the sealed water tank body 22 shakes, stress due to the displacement is applied to the connection points of the water tank inlet pipe 23 and the circulating water pipe 24, which may cause pipe damage.

[0006] This invention has been made in view of the above problems, and aims to provide an inert gas-sealed water tank for temporarily storing degassed pure water or ultrapure water, which reduces the possibility of damage due to earthquakes and other events, and improves the safety and workability of maintenance. [Means for solving the problem]

[0007] In view of the above objectives, the present invention provides an inert gas seal tank comprising a seal tank body for storing degassed pure water, a tank inlet pipe and a tank outlet pipe connected to the seal tank body, and an inert gas supply pipe, wherein the upper space can be filled with inert gas from the inert gas supply pipe to prevent oxygen and carbon dioxide from redissolving into the pure water supplied from the tank inlet pipe into the seal tank body, and the tank inlet pipe and the tank outlet pipe are connected to the side surface of the seal tank body (Invention 1).

[0008] According to this invention (Invention 1), by connecting the tank inlet piping and the tank outlet piping to the side of the sealed tank body, the impact on the tank inlet piping and the tank outlet piping can be minimized even if the sealed tank body vibrates due to an earthquake or the like, thereby reducing the possibility of damage to the inert gas sealed tank due to an earthquake. Furthermore, since the tank inlet piping is connected from the side, operations such as adjusting the flow rate of the valve and maintenance can be performed from the side of the tank, improving the safety and workability of maintenance.

[0009] In the above invention (Invention 1), it is preferable that the circulating water inlet pipe is connected to the side surface of the seal water tank body (Invention 2).

[0010] According to this invention (Invention 2), by connecting the circulating water inlet piping to the side of the seal tank body, even if the seal tank body vibrates due to an earthquake or the like, the impact on the circulating water inlet piping can be minimized, thereby reducing the possibility of damage due to earthquakes.

[0011] In the above invention (Invention 1), it is preferable that an overflow pipe is connected to the side of the seal tank body and that an inert gas seal pot is provided at the end of the overflow pipe (Invention 3).

[0012] According to this invention (Invention 3), the pressure of the inert gas inside the sealed water tank can be properly maintained by the seal pot.

[0013] In the above invention (Invention 1), it is preferable that the water tank inlet piping and the water tank outlet piping are connected to the seal water tank body at a position of 1 / 2 or less in the height direction of the seal water tank body (Invention 4).

[0014] According to this invention (Invention 4), since the water tank inlet piping and the water tank outlet piping are connected at a relatively low position, the workability of operations such as adjusting the flow rate of the valve and maintenance work from the side of the tank can be further improved.

[0015] In the above invention (Invention 1), it is preferable that expansion joints are provided in the water tank inlet piping and the water tank outlet piping (Invention 5).

[0016] According to this invention (Invention 5), even if the inert gas seal tank vibrates due to an earthquake or the like, the vibration of the tank inlet piping and the tank outlet piping can be dampened, further reducing the possibility of damage due to earthquakes. In addition, the seal tank body deforms slightly as the water level inside the seal tank body rises and falls, but the stress at this time can be absorbed by the expansion joint, thus reducing the load on the inert gas seal tank.

[0017] In the above invention (Invention 3), it is preferable that an expansion joint is provided in the overflow piping (Invention 6).

[0018] According to this invention (Invention 6), even if the inert gas seal tank vibrates due to an earthquake or the like, the vibration of the overflow piping can be dampened, further reducing the possibility of damage due to earthquakes. [Effects of the Invention]

[0019] The inert gas seal tank of the present invention reduces the possibility of damage due to earthquakes because the tank inlet piping and tank outlet piping are connected to the side of the seal tank body. Furthermore, operations such as adjusting the flow rate of the valve and maintenance can be performed from the side of the tank, improving the safety and workability of maintenance. As a result, the inert gas seal tank of the present invention improves the maintainability of the device, the safety of operations, and the workability of the inert gas seal tank. [Brief explanation of the drawing]

[0020] [Figure 1] This is a schematic longitudinal cross-sectional view showing an inert gas-sealed water tank according to one embodiment of the present invention. [Figure 2] This is a plan view of the aforementioned inert gas seal water tank. [Figure 3] It is a longitudinal sectional view schematically showing an inert gas sealed water tank according to an embodiment of the conventional invention.

[0021] Hereinafter, an inert gas sealed water tank according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2.

[0022] (Inert gas sealed water tank) FIG. 1 is a side view schematically showing an inert gas sealed water tank according to an embodiment of the present invention, and FIG. 2 is a plan view thereof. In FIGS. 1 and 2, the inert gas sealed water tank 1 has a cylindrical sealable water tank body 2, a water tank inlet nozzle 3 and a circulating water inlet nozzle 4 attached to the side of the water tank body 2. A water tank inlet pipe 3A communicating with a primary pure water device (not shown) and a circulating water inlet pipe 4A returning from a use point or the like are connected to the water tank inlet nozzle 3 and the circulating water inlet nozzle 4, respectively. The water tank inlet pipe 3A and the circulating water inlet pipe 4A each have expansion joints 3B and 4B. Further, in the present embodiment, the insertion ends (tip portions) of the water tank inlet nozzle 3 and the circulating water inlet nozzle 4 are refracted in the horizontal direction in a direction away from the water tank outlet nozzle described later, and are further refracted upward by about 30 to 60°, for example, 45°. Thereby, the pure water W can be discharged in a direction away from the water tank outlet nozzle described later.

[0023] Furthermore, on the side surface side of the seal water tank body 2, an overflow pipe 5 communicating with a seal pot 5A of nitrogen gas and provided with an expansion joint 5B in the middle is connected, and a water tank outlet nozzle 6 and a spare nozzle 7 are provided. A water tank outlet pipe 6A and a spare pipe 7A having expansion joints 6B and 7B are connected to the water tank outlet nozzle 6 and the spare nozzle 7. The positions of the water tank inlet nozzle 3, the circulating water inlet nozzle 4, the overflow pipe 5, the water tank outlet nozzle 6 and the spare nozzle 7 are all shown in the longitudinal sectional view. For the sake of convenience, in FIG. 1, they are shown with a change in the angle in the plane.

[0024] In addition, at the top of the sealed water tank main body 2, a nitrogen gas seal pipe 8 communicating with a nitrogen gas source 8A as an inert gas source, a nitrogen gas pilot pipe 9 communicating with a pressure detection means 9A, and an openable and closable ventilation pipe 10 communicating with the external environment 10A are connected.

[0025] (Method of using an inert gas sealed water tank) In the inert gas sealed water tank 1 as described above, degassed pure water W is supplied from a water tank inlet nozzle 3 into the sealed water tank main body 2 via a water tank inlet pipe 3A from a pure water production device (which may be an ultrapure water production device) not shown in the figure and stored. Subsequently, nitrogen gas (N2) supplied from a nitrogen gas source 8A as an inert gas source is injected from the nitrogen gas seal pipe 8 into the space above the water surface of the stored pure water W to discharge existing air and seal it with nitrogen gas (N2). Thereby, oxygen and carbon dioxide gas are prevented from redissolving into the pure water W while the pure water W is stored in the inert gas sealed water tank 1. Then, the pure water W in the inert gas sealed water tank 1 is sent to a subsystem formed by combining a use point, an ultraviolet sterilizer, a cartridge polisher, an ultrafiltration membrane device, etc. from a water tank outlet pipe connected to the water tank outlet nozzle 6. And the pure water W that has not been used is refluxed via the circulation water inlet nozzle 4 from the circulation water inlet pipe 4A as necessary.

[0026] At this time, excess pure water W is discharged from the overflow pipe 5 so that the amount of pure water W stored in the sealed water tank main body 2 does not become excessive. Alternatively, the internal pressure of the sealed water tank main body 2 by nitrogen gas (N2) is monitored by the pressure detection means 9A of the nitrogen gas pilot pipe 9, and the internal pressure is maintained substantially equal to the atmospheric pressure by the seal pot 5A. <(

[0027] In this inert gas sealed water tank 1, since the water tank inlet nozzle 3, the circulation water inlet nozzle <4 and the water tank outlet nozzle <6 are provided on the side surface of the sealed water tank main body 2, operations such as flow rate adjustment of the valve of the water tank inlet nozzle 3 and maintenance can be accessed from the side of the tank and performed. Particularly in this embodiment, since it is below 1 / 2 of the height of the sealed water tank main body 2, the safety and workability of maintenance are improved.

[0028] Moreover, even if the inert gas seal tank 1 (seal tank body 2) vibrates due to an earthquake or the like, the impact on the tank inlet nozzle 3, circulating water inlet nozzle 4, tank outlet nozzle 6, and spare nozzle 7 can be minimized, reducing the possibility of damage due to earthquakes. Furthermore, since expansion joints 3B, 4B, 6B, and 7B are provided in the tank inlet piping 3A, circulating water inlet piping 4A, tank outlet piping 6A, and spare piping 7A, even if the seal tank body 2 vibrates due to an earthquake or the like, the vibrations of the tank inlet piping 3A, circulating water inlet piping 4A, and tank outlet piping 6A can be further attenuated. In addition, the seal tank body 2 deforms slightly as the water level of the pure water W filled inside the seal tank body 2 rises and falls, but the stress at this time can be absorbed by the expansion joints, thus reducing the load on the inert gas seal tank 1.

[0029] Furthermore, in this embodiment, since the overflow pipe 5 is also provided with an expansion joint 5B, even if the seal tank body 2 vibrates due to an earthquake or the like, the vibration of the overflow pipe 5 can be dampened, further reducing the possibility of damage due to earthquakes.

[0030] The inert gas seal water tank 1 of the present invention has been described above based on the above embodiments, but the present invention is not limited to the above embodiments and can be modified in various ways. For example, the seal water tank body 2 is not limited to a cylindrical shape but can be applied to various shapes such as a square tube. Also, the liquid stored in the seal water tank body 2 is not limited to deaerated pure water W, but may be a chemical solution such as dilute ammonia water. In this specification, deaerated pure water W also includes ultrapure water. [Explanation of symbols]

[0031] 1. Inert gas sealed water tank 2. Seal tank body 3. Aquarium Inlet Nozzle 3A Aquarium Inlet Piping 3B Expansion Joint 4. Circulating water inlet nozzle 4A Circulating water inlet piping 4B Expansion Joint 5. Overflow piping 5A Seal Pot 5B Expansion Joint 6. Tank outlet nozzle 6A Water Tank Outlet Piping 6B Expansion Joint 7 Spare nozzles 7A Spare piping 7B Expansion joint 8. Nitrogen gas sealing piping 8A Nitrogen gas source 9. Nitrogen gas pilot piping 9A Pressure detection means 10 Ventilation piping 10A external environment W Pure water

Claims

1. An inert gas seal tank comprising a seal tank body for storing degassed pure water, a tank inlet pipe and a tank outlet pipe connected to the seal tank body, and an inert gas supply pipe, wherein in order to prevent oxygen and carbon dioxide from redissolving into the pure water supplied from the tank inlet pipe into the seal tank body, an inert gas can be filled into the space above the water surface of the pure water in the seal tank body from the inert gas supply pipe, The tank inlet pipe and the tank outlet pipe are connected to the side of the sealed tank body. An inert gas seal tank, wherein the tank inlet piping is bent within the seal tank body so as to discharge pure water away from the tank outlet piping and at an upward angle of 30 to 60° with respect to the horizontal.

2. The inert gas seal tank according to claim 1, wherein a circulating water inlet pipe is connected to the side of the seal tank body.

3. The inert gas seal tank according to claim 1, wherein an overflow pipe is connected to the side of the seal tank body and an inert gas seal pot is provided at the end of the overflow pipe.

4. The inert gas seal tank according to claim 1, wherein the tank inlet piping and the tank outlet piping are connected to the seal tank body at a position of 1 / 2 or less in the height direction of the seal tank body.

5. The inert gas-sealed water tank according to claim 1, wherein expansion joints are provided in the water tank inlet piping and the water tank outlet piping.

6. The inert gas seal water tank according to claim 3, wherein an expansion joint is provided in the overflow piping.

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