Ultrapure water production equipment

Abstract

To provide an ultrapure water production facility capable of preventing residual water in a bypass channel from mixing with ultrapure water.SOLUTION: Water in a sub-tank 1 is treated by a pump 2, a heat exchange device 3, a UV oxidation device 4, a deionization device 5, and a UF membrane separation device 7 to make ultrapure water. A bypass flow path 20 is provided to bypass the UF membrane separator 7. The bypass flow path 20 has first piping 21, a first valve 22, second piping 23, a second valve 24, and third piping 25. The first piping 21 is connected to piping 6 and the third piping 25 is connected to piping 8. Lengths of the piping 21 and 25 are short.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to ultrapure water production equipment, and particularly to ultrapure water production equipment in which a filtration device is installed at the final stage. More specifically, the present invention relates to ultrapure water production equipment provided with a bypass flow path so as to bypass this filtration device.

Background Art

[0002] In ultrapure water production equipment, water in a sub-tank for storing primary pure water is treated by a pump, a heat exchanger, an ultraviolet (UV) oxidation device, a deionization device, and an ultrafiltration (UF) membrane separation device to become ultrapure water. The produced ultrapure water is sent to a use point via a pipe (supply line), and a part of it is used (for example, for washing semiconductors) at the use point, and the unused ultrapure water is returned to the sub-tank via a pipe (return line).

[0003] Primary pure water can be obtained, for example, by subjecting raw water such as industrial water, well water, and municipal water to pretreatment such as coagulation sedimentation, and then sequentially performing reverse osmosis membrane separation treatment, treatment with anionic and cationic ion exchange resins, and further reverse osmosis membrane treatment.

[0004] Patent Document 1 describes providing a bypass flow path that bypasses the UF membrane separation device of ultrapure water production equipment. A valve is provided in this bypass flow path, and the opening and closing of the valve is switched so that the sterilization drainage and rinse drainage of other equipment bypass the UF membrane separation device.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In conventional ultrapure water production facilities that have a bypass channel that bypasses the UF membrane separator, water remains in the bypass channel. When this residual water mixes with the ultrapure water, the quality of the ultrapure water deteriorates.

[0007] The object of this invention is to provide an ultrapure water production system that prevents residual water in the bypass channel from mixing with ultrapure water. [Means for solving the problem]

[0008] [1] An ultrapure water production facility having a filtration device and a bypass channel that bypasses the filtration device, characterized in that a first on-off valve is provided at the uppermost part of the bypass channel and a second on-off valve is provided at the lowermost part.

[0009] [2] An ultrapure water production facility of [1] having a discharge means for discharging residual water from a flow path between the first on-off valve and the second on-off valve.

[0010] [3] The ultrapure water production facility [2] has a drain valve provided at one end of the flow path between the first on-off valve and the second on-off valve, and a purge gas supply means for supplying purge gas to the other end.

[0011] [4] The purge gas is nitrogen gas. [3] An ultrapure water production facility.

[0012] [5] An ultrapure water production facility of any of [1] to [4], wherein the length of the piping from the upstream end of the bypass channel to the first on-off valve is 0.3 m or less, and the length of the piping from the downstream end of the bypass channel to the second on-off valve is 0.3 m or less.

[0013] [6] An ultrapure water production facility of any of [1] to [5], wherein the first and second on-off valves are made of fluororesin.

[0014] [7] An ultrapure water production facility having a filtration device and a bypass channel that bypasses the filtration device, characterized in that a first on-off valve is provided at the uppermost part of the bypass channel, and a discharge means is provided for discharging residual water in the bypass channel downstream of the first on-off valve. [Effects of the Invention]

[0015] In one aspect of the present invention, since first and second on-off valves are provided in the bypass channel, it is prevented that water flows through the bypass channel in a short circuit and mixes with the ultrapure water, thereby preventing a deterioration in the quality of the ultrapure water.

[0016] In one aspect of the present invention, the length of the piping upstream of the first on-off valve and downstream of the second on-off valve in the bypass flow path is shortened, so that the amount of residual water in these pipes is reduced, and the deterioration of the ultrapure water quality is prevented.

[0017] In one aspect of the present invention, residual water in the bypass channel is discharged, so that the residual water in the bypass channel does not mix with the ultrapure water, thereby preventing a deterioration in the quality of the ultrapure water.

[0018] In one aspect of the present invention, by introducing nitrogen gas as a purge gas into the bypass channel, the mixing of air into the ultrapure water is prevented, thereby preventing a deterioration in the quality of the ultrapure water (increase in dissolved oxygen concentration). [Brief explanation of the drawing]

[0019] [Figure 1] This is a diagram showing the configuration of an ultrapure water production facility according to an embodiment. [Figure 2] This is an enlarged view of a portion of Figure 1 (the UF membrane separation apparatus). [Modes for carrying out the invention]

[0020] The embodiments will be described below with reference to Figures 1 and 2.

[0021] FIG. 1 is an overall configuration diagram of an ultrapure water production facility according to an embodiment. The water in the sub-tank 1 for storing primary pure water is treated by a pump 2, a heat exchanger 3, an ultraviolet (UV) oxidation device 4, a deionization device 5 such as an ion exchange device, and a UF membrane separation device 7 to become ultrapure water. The produced ultrapure water is sent to a use point 9 via a pipe (supply line) 8, a part of which is used at the use point 9, and the unused ultrapure water is returned to the sub-tank 1 via a pipe (return line) 10.

[0022] As shown in FIG. 2, in this embodiment, the UF membrane separation device 7 has a configuration including a plurality of UF membrane modules 7a arranged in parallel, but is not limited thereto.

[0023] Also, as shown in FIG. 2, a valve 11 is provided in a pipe 6 for supplying water from the deionization device 5 to the UF membrane separation device 7. Further, a valve 12 is provided in a pipe 8 for sending out ultrapure water from the UF membrane separation device 7.

[0024] In this embodiment, a bypass flow path 20 is provided so as to bypass the UF membrane separation device 7. The upstream end of the bypass flow path 20 is connected to a pipe 6 on the upstream side of the valve 11. Also, the downstream end of the bypass flow path 20 is connected to a pipe 8 on the downstream side of the valve 12.

[0025] As shown in FIG. 2, this bypass flow path 20 includes a first pipe 21, a first valve (first on-off valve) 22, a second pipe 23, a second valve (second on-off valve) 24, and a third pipe 25 that are connected from the pipe 6 side toward the pipe 8 side. The first pipe 21 is connected to the pipe 6, and the third pipe 25 is connected to the pipe 8. The lengths of the pipes 21 and 25 are each as short as 0.3 m or less. The valve may have a connection dimension with the pipe that exceeds 0.3 m in order to avoid interference with the welding line of the joint including the pipe and the flange.

[0026] One end of a pipe 30 having a valve 31 is connected to the portion of the second pipe 23 closest to the first valve 22, and a purge gas source 32 such as a nitrogen gas cylinder is provided at the other end of the pipe 30. A drain pipe 34 having a drain valve 33 is connected to the portion of the second pipe 23 closest to the second valve 24.

[0027] Each valve is preferably made of a fluororesin such as PTFE. In particular, valves 12, 22, and 24 are preferably made of fluororesin.

[0028] In this ultrapure water production facility, during the normal ultrapure water production process, valves 11 and 12 are open, and valves 22, 24, 31, and 33 are closed. Water from the deionizer 5 passes through the UF membrane separator 7, becomes ultrapure water, and is sent from the piping 8 to the point of use 9.

[0029] During the startup operation of the ultrapure water production facility, the deionizer 5 and the area upstream of it are cleaned. To prevent the cleaned wastewater (including rinse wastewater) from passing through the UF membrane separator 7, valves 11 and 12 are closed, and the first and second valves 22 and 24 are opened. Valves 31 and 33 are closed. As a result, the cleaned wastewater flows only through the bypass channel 20 and does not pass through the UF membrane separator 7. After the cleaning is complete, valves 22 and 24 are closed, and valves 11 and 12 are opened.

[0030] Furthermore, when sterilizing parts of the ultrapure water production facility other than the UF membrane separator 7, in order to prevent the sterilized water from passing through the UF membrane separator 7, valves 11 and 12 are closed and the first and second valves 22 and 24 are opened, as described above. Valves 31 and 33 are closed. After sterilization is complete, valves 22 and 24 are closed and valves 11 and 12 are opened.

[0031] After the above cleaning or sterilization is completed, cleaning or sterilization wastewater remains in the second pipe 23. Therefore, in this embodiment, the drain valve 33 is opened and the valve 31 is closed, a purge gas such as nitrogen gas is introduced into the pipe 23, and the residual water in the pipe 23 is discharged from the drain pipe 34.

[0032] After the residual water has been drained, valves 31 and 33 are closed.

[0033] In this embodiment, since the first and second valves 22 and 24 are provided in the bypass channel 20, water from the deionizer 5 is prevented from passing through the bypass channel 20 in a short circuit and mixing with the ultrapure water, thereby preventing a deterioration in the quality of the ultrapure water.

[0034] Furthermore, because pipes 21 and 25 are made extremely short, the amount of residual water in pipes 21 and 25 is small, preventing the deterioration of the ultrapure water quality caused by this residual water mixing with the ultrapure water.

[0035] Furthermore, since residual water in pipe 23 is discharged, the residual water in pipe 23 does not mix with the ultrapure water, thus preventing a deterioration in the quality of the ultrapure water.

[0036] Furthermore, by introducing nitrogen gas as a purge gas into the piping 23, the mixing of air into the ultrapure water is prevented, thus preventing a deterioration in the quality of the ultrapure water (increase in dissolved oxygen concentration). [Explanation of Symbols]

[0037] 1 Sub-tank 2. Ultraviolet oxidation apparatus 5. Deionizer 7 UF membrane separation equipment 20 Bypass channel 21. First Piping 22. Valve No. 1 23. Second Piping 25. Second valve 25 Third Piping 32. Purge gas source 33 Drain valve

Claims

1. In an ultrapure water production facility having a filtration device and a bypass channel that bypasses the filtration device, An ultrapure water production facility is provided in which a first on-off valve is installed at the uppermost part of the bypass channel and a second on-off valve is installed at the lowermost part, It has a discharge means for discharging residual water from the flow path between the first on-off valve and the second on-off valve, The discharge means is an ultrapure water production facility having a drain valve provided at one end of the flow path between the first on-off valve and the second on-off valve, and a purge gas supply means for supplying purge gas to the other end.

2. The ultrapure water production apparatus according to claim 1, wherein the purge gas is nitrogen gas.

3. The length of the piping from the upstream end of the bypass channel to the first on-off valve is 0.3 m or less. The ultrapure water production apparatus according to claim 1 or 2, wherein the length of the piping from the downstream end of the bypass channel to the second shut-off valve is 0.3 m or less.

4. An ultrapure water production apparatus according to any one of claims 1 to 3, wherein the first on-off valve and the second on-off valve are made of fluororesin.

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