Purified water supply system

Abstract

To provide a purified water supply system capable of reducing a capacity of an electric deionizer.SOLUTION: A purified water supply system includes a reverse osmosis membrane device, a tank, a membrane filtration device positioned downstream of the tank to separate reverse osmosis treated water into filtered water and concentrated water, an electric deionizer positioned in a water delivery line, and a concentrated water line connecting the membrane filtration device to a point downstream of the electric deionizer in the water delivery line, through which the concentrated water flows.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a purified water supply system. [Background technology]

[0002] There is a purified water supply system that includes a reverse osmosis membrane device, an electrodeionization device, and an ultrafiltration device. Patent Document 1 discloses a purified water supply system in which a reverse osmosis membrane device, an electrodeionization device, and an ultrafiltration device are provided in this order on a water supply line. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-32884 Summary of the Invention [Problem to be solved by the invention]

[0004] In the purified water supply system described in Patent Document 1, an electrodeionization device and an ultrafiltration device are provided in a closed water supply line. In this purified water supply system, concentrated water from the ultrafiltration device passes through the electrodeionization device again. This makes it difficult to reduce the capacity of the electrodeionization device.

[0005] An object of the present invention is to provide a purified water supply system that allows the capacity of an electrodeionization device to be reduced. [Means for solving the problem]

[0006] (1) A purified water supply system includes a reverse osmosis membrane device, a tank for storing reverse osmosis membrane-treated water produced in the reverse osmosis membrane device, a water supply line connecting the reverse osmosis membrane device to the tank, an ultrafiltration device located downstream of the tank and separating the reverse osmosis membrane-treated water into filtered water and concentrated water, a water supply line connecting the tank to the ultrafiltration device, an electrodeionization device located on the water supply line, a concentrated water line connecting the ultrafiltration device to the water supply line downstream of the electrodeionization device and through which concentrated water flows, a pump and a heat exchanger located downstream of the connection point with the concentrated water line on the water supply line, and a water supply valve located upstream of the connection point on the water supply line.

[0007] In the purified water supply system (1), water to be treated is converted into reverse osmosis-treated water by a reverse osmosis membrane device, and the reverse osmosis-treated water is supplied to a tank through a water supply line. During the water supply process, when the water supply valve is opened, the reverse osmosis-treated water is supplied from the tank through the water supply line to an electrodeionization device, where ions are removed. The reverse osmosis-treated water is then supplied to an ultrafiltration device through the water supply line (via a pump and a heat exchanger), where it is separated into filtrate and concentrated water by the ultrafiltration device. The concentrated water flows through the concentrated water line and into the water supply line from a connection. In this way, the concentrated water circulates through the pump, heat exchanger, and ultrafiltration device in part of the water supply line and the concentrated water line. In other words, the concentrated water does not pass through the electrodeionization device, allowing the electrodeionization device's capacity to be reduced.

[0008] (2) The purified water supply system further includes a filtered water line connecting the ultrafiltration device and the tank, a bypass line connecting the concentrated water line and the water supply line upstream of the electrodeionization device, and a bypass valve disposed in the bypass line.

[0009] In the purified water supply system (2), the filtered water is returned from the ultrafiltration unit to the tank through the filtered water line. Furthermore, during the sterilization process, when the bypass valve is opened and the water supply valve is closed, the reverse osmosis membrane-treated water flows through the bypass line to the concentrated water line. In other words, during the above process, the filtered water is supplied to the concentrated water line without passing through the electrodeionization unit. Therefore, there is no need to install an electrodeionization unit with hot water sterilization specifications.

[0010] (3) The purified water supply system further includes a control unit that controls the pump, the water supply valve, and the bypass valve. The control unit further includes a water flow control unit that opens the water supply valve, closes the bypass valve, and drives the pump, and a sterilization control unit that closes the water supply valve, opens the bypass valve, and drives the pump.

[0011] According to the purified water supply system of (3), the control unit has a water flow control unit and a sterilization control unit, so that the water flow process and the control process can be switched over. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a purified water supply system that allows the capacity of an electrodeionization device to be reduced. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic configuration diagram of a purified water supply system according to a first embodiment. [Figure 2] FIG. 2 is a block diagram showing a control configuration of the purified water supply system. [Figure 3] FIG. 2 is a schematic diagram of a purified water supply system showing the flow of water during a water passing step. [Figure 4] FIG. 2 is a schematic diagram of a purified water supply system showing the flow of water in a sterilization process. DETAILED DESCRIPTION OF THE INVENTION

[0014] 1. First embodiment (1) Basic configuration of purified water supply system A purified water supply system 1 according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic diagram of the purified water supply system according to the first embodiment.

[0015] The purified water supply system 1 is a system for producing purified water by removing impurities from raw water.

[0016] The purified water supply system 1 mainly includes a reverse osmosis membrane device 2, a tank 3, an ultrafiltration device 5, an electrodeionization device (EDI device) 7, a pump 9, and a heat exchanger 10. The purified water supply system 1 further includes a water supply line 4, a water delivery line 6, a concentrated water line 8, a filtered water line 13, and a bypass line 14.

[0017] (2) Detailed configuration of the purified water supply system The reverse osmosis membrane device 2 is equipped with a reverse osmosis membrane (RO membrane) and is a device that filters impurities contained in raw water P1 (water to be treated) to separate the raw water P1 into reverse osmosis membrane-treated water P2 from which the impurities have been removed and concentrated wastewater containing impurities. The concentrated wastewater is then discharged to the outside.

[0018] The tank 3 is a tank for storing reverse osmosis membrane treated water P2. The tank 3 is connected to the reverse osmosis membrane device 2 via a water supply line 4. The water supply line 4 is a flow path extending from the reverse osmosis membrane device 2 to the tank 3, and supplies the reverse osmosis membrane treated water P2 to the tank 3.

[0019] The ultrafiltration device 5 is connected to the tank 3 via a water supply line 6. The ultrafiltration device 5 is disposed downstream of the tank 3. The water supply line 6 is a flow path extending from the tank 3 to the ultrafiltration device 5. The ultrafiltration device 5 has an ultrafiltration membrane (UF membrane) and is a device that separates the reverse osmosis membrane treated water P2 into filtered water P3 (purified water) and concentrated water P4 by removing fine particles and the like contained in the reverse osmosis membrane treated water P2.

[0020] The electrodeionization device 7 is disposed on the water supply line 6. The electrodeionization device 7 is disposed upstream of the ultrafiltration device 5. The electrodeionization device 7 is a device that performs a deionization (demineralization) process on the reverse osmosis membrane-treated water P2. This removes ions (cations and anions) from the reverse osmosis membrane-treated water P2.

[0021] The ultrafiltration device 5 is connected to a connection point 11, which is a point on the water supply line 6 upstream of the electrodeionization device 7, via a concentrated water line 8. The concentrated water line 8 is a flow path extending from the ultrafiltration device 5 to the connection point 11, and supplies concentrated water P4 from the ultrafiltration device 5 to the connection point 11.

[0022] The pump 9 is disposed in the water supply line 6 between the electrodeionization device 7 and the ultrafiltration device 5. The pump 9 supplies the reverse osmosis membrane-treated water P2 to the ultrafiltration device 5 via the water supply line 6 at a predetermined water pressure.

[0023] The heat exchanger 10 is disposed in the water supply line 6 between the electrodeionization device 7 and the ultrafiltration device 5. The heat exchanger 10 is disposed downstream of the pump 9. The heat exchanger 10 heats the reverse osmosis membrane-treated water P2 to produce hot water. Specifically, the heat exchanger 10 heats the reverse osmosis membrane-treated water P2 by supplying steam thereto. For example, the heat exchanger 10 heats the reverse osmosis membrane-treated water P2 to, for example, 85°C and supplies the heated water as hot water.

[0024] The connection 11 (the portion of the water supply line 6 to which the downstream end of the concentrated water line 8 is connected) is provided between the electrodeionization device 7 and the pump 9 and heat exchanger 10. Therefore, the concentrated water P4 is not supplied upstream of the electrodeionization device 7.

[0025] The water supply line 6 is provided with a water supply valve 12. Specifically, the water supply valve 12 is disposed upstream of the connection part 11 in the water supply line 6. The water supply valve 12 is configured as a solenoid valve that can be switched between a fully open and a fully closed state, or a control valve that can adjust the opening degree.

[0026] The ultrafiltration device 5 is connected to the tank 3 via a filtered water line 13. The filtered water line 13 is a flow path for supplying the filtered water P3 from the ultrafiltration device 5 to a point-of-use UP and returning unused filtered water P5 to the tank 3. The point-of-use UP is a facility, device, location, etc. where the filtered water P3 is used.

[0027] (3) Bypass structure used in the sterilization process The purified water supply system 1 has a bypass line 14. The bypass line 14 is a flow path that connects the concentrated water line 8 to the upstream side of the electrodeionization device 7 in the water supply line 6. In other words, the bypass line 14 is arranged in parallel with the upstream portion of the water supply line 6 that extends to the connection portion 11, and connects the water supply line 6 and the concentrated water line 8.

[0028] The bypass line 14 is provided with a bypass valve 15. The bypass valve 15 is configured by a solenoid valve that can be switched between a fully open and a fully closed state, or a control valve that can adjust the opening degree.

[0029] The water supply valve 12 and the bypass valve 15 allow the flow of reverse osmosis membrane treated water P2 from the tank 3 to be switched between a first flow path that passes through the electrodeionization device 7 and a second flow path that bypasses the electrodeionization device 7 (described below).

[0030] (4) Control configuration The control configuration of the purified water supply system 1 will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the control configuration of the purified water supply system. The purified water supply system 1 has a control unit 21.

[0031] The control unit 21 is a computer system having a processor (e.g., a CPU), a storage device (e.g., a ROM, a RAM, a HDD, an SSD, etc.), and various interfaces (e.g., an A / D converter, a D / A converter, a communication interface, etc.) The control unit performs various control operations by executing programs stored in the storage unit (corresponding to part or all of the storage area of ​​the storage device).

[0032] The control unit 21 controls the pump 9 , the heat exchanger 10 , the water supply valve 12 , and the bypass valve 15 .

[0033] Specifically, the control unit 21 includes a water flow control unit 22 and a sterilization control unit 23.

[0034] In the water flow process, the water flow control unit 22 opens the water supply valve 12, closes the bypass valve 15, and drives the pump 9.

[0035] In the sterilization step, the sterilization control unit 23 closes the water supply valve 12, opens the bypass valve 15, and drives the pump 9 and the heat exchanger 10.

[0036] (5) Water passage process The water flow process will be explained using Figure 3. Figure 3 is a schematic diagram of the purified water supply system, showing the flow of water in the water flow process. In the water flow process, treated water is constantly circulated at room temperature and supplied to the point of use UP as needed. In Figure 3, the actual flow of water is indicated by a thick line.

[0037] (5-1) Flow of reverse osmosis treated water (tank → ultra treatment device) Because the water flow control unit 22 opens the water supply valve 12 and closes the bypass valve 15, the reverse osmosis membrane-treated water P2 is supplied from the tank 3 through the water supply line 6 to the electrodeionization device 7, where ions are removed. The reverse osmosis membrane-treated water P2 is then supplied through the water supply line 6 (via the pump 9 and the heat exchanger 10) to the ultrafiltration device 5. The reverse osmosis membrane-treated water P2 is separated by the ultrafiltration device 5 into filtrate P3 and concentrated water P4.

[0038] (5-2) Flow of concentrated water (ultrafiltration device → connection part) The concentrated water P4 passes through the concentrated water line 8 and flows into the water supply line 6 from the connection part 11.

[0039] As described above, concentrated water P4 circulates through part of water supply line 6 (from connection 11 to ultrafiltration device 5) and concentrated water line 8, passing through pump 9, heat exchanger 10, and ultrafiltration device 5. In other words, concentrated water P4 does not pass through electrodeionization device 7, allowing the capacity of electrodeionization device 7 to be reduced. This reduces the power consumption of electrodeionization device 7 and the cost of producing purified water.

[0040] (5-3) Flow of filtered water (ultrafiltration device → point of use → tank) The filtered water P3 is supplied to the point of use UP through the filtered water line 13. The unused filtered water P5 is returned to the tank 3 through the filtered water line 13.

[0041] (6) Sterilization process The sterilization process will be explained using Figure 4. Figure 4 is a schematic diagram of a purified water supply system showing the flow of water in the sterilization process. The sterilization process is carried out to suppress the growth of bacteria in the device or piping. The sterilization process is carried out at a predetermined timing, for example, for 30 minutes or more. In Figure 4, the actual flow of water is indicated by a thick line.

[0042] (6-1) Flow of reverse osmosis treated water (tank → ultra treatment device) Because the sterilization control unit 23 closes the water supply valve 12 and opens the bypass valve 15, the reverse osmosis membrane-treated water P2 is supplied from the tank 3 through the bypass line 14 to the concentrated water line 8 and then flows into the water supply line 6 at the connection part 11. The reverse osmosis membrane-treated water P2 then passes through the pump 9 and the heat exchanger 10 in the water supply line 6 and is supplied to the ultrafiltration device 5. The reverse osmosis membrane-treated water P2 is heated by the heat exchanger 10. As a result, the temperature of the reverse osmosis membrane-treated water P2 becomes, for example, 85°C. As a result, the ultrafiltration device 5 is sterilized with hot water. The reverse osmosis membrane-treated water P2 is separated by the ultrafiltration device 5 into filtrate P3 and concentrated water P4.

[0043] As described above, in the sterilization process, hot water does not pass through the electrodeionization device 7. Therefore, there is no need to configure the electrodeionization device 7 for hot water sterilization. As a result, the cost of the electrodeionization device 7 can be reduced.

[0044] (6-2) Flow of concentrated water (ultrafiltration device → connection part) The concentrated water P4 passes through the concentrated water line 8 and flows into the water supply line 6 from the connection part 11.

[0045] As described above, the concentrated water P4 is circulated through a part of the water supply line 6 and the concentrated water line 8, passing through the pump 9, the heat exchanger 10, and the ultrafiltration device 5.

[0046] (6-3) Flow of filtered water (ultrafiltration device → tank) The filtered water P3 flows through the filtered water line 13 and returns to the tank 3 as unused filtered water P5.

[0047] (7) Effects A number of advantages of this embodiment will be described below. Each advantage may be obtained alone, or a number of advantages may be obtained simultaneously.

[0048] (7-1) The electrodeionization device 7 and the ultrafiltration device 5 are directly connected via a water supply line 6. In other words, the two devices are connected without an intermediate storage tank. This allows for space-saving in the purified water supply system 1 and reduces the installation costs of the various devices.

[0049] (7-2) In a system in which the electrodeionization device 7 and the ultrafiltration device 5 are directly connected, the reverse osmosis membrane device 2 is disposed upstream of the circulation flow path (e.g., the water supply line 6 and the filtered water line 13) of the ultrafiltration device 5. Therefore, even if the ultrafiltration device 5 is constantly operating in circulation, the reverse osmosis membrane device 2 does not constantly discharge concentrated wastewater. In other words, the amount of concentrated wastewater from the reverse osmosis membrane device 2 can be reduced.

[0050] (7-3) In the water passing step, concentrated water P4 discharged from the ultrafiltration unit is circulated through a part of the water supply line 6 and the concentrated water line 8, via the pump 9, the heat exchanger 10, and the ultrafiltration unit 5. In other words, because concentrated water P4 does not pass through the electrodeionization unit 7, the capacity of the electrodeionization unit 7 can be reduced.

[0051] (7-4) During the sterilization process, the hot water flowing from the tank 3 is passed through the bypass line 14, so that the hot water does not pass through the electrodeionization device 7. This eliminates the need to install the electrodeionization device 7 in a hot water sterilization configuration. As a result, the cost of the electrodeionization device 7 can be reduced.

[0052] 2. Other Embodiments Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention.

[0053] 3. Contribution to the United Nations-led Sustainable Development Goals (SDGs) This disclosure includes matters that contribute to achieving Goal 6 of the SDGs (Sustainable Development Goals), "Clean water and sanitation," and Goal 9, "Industry, innovation and infrastructure." [Explanation of symbols]

[0054] 1: Purified water supply system 2: Reverse osmosis membrane device 5: Ultrafiltration device 6: Water supply line 7: Electrodeionizer 8: Concentrated water line 9: Pump 10: Heat exchanger 11: Connection part 12: Water valve 14: Bypass line 15: Bypass valve 21: Control unit 22: Water flow control section 23: Sterilization control unit P2: Reverse osmosis treated water P3: Filtered water (purified water) P4: Concentrated water

Claims

1. A reverse osmosis membrane device; a tank for storing reverse osmosis membrane-treated water produced in the reverse osmosis membrane device; a water supply line connecting the reverse osmosis membrane device and the tank; an ultrafiltration device disposed downstream of the tank and configured to separate the reverse osmosis membrane treated water into filtered water and concentrated water; a water supply line connecting the tank and the ultrafiltration device; an electrodeionization device disposed on the water supply line; a concentrated water line connecting the ultrafiltration device to a downstream side of the electrodeionization device in the water supply line, through which concentrated water flows; a pump and a heat exchanger disposed downstream of a connection portion between the water supply line and the concentrated water line; a water supply valve disposed upstream of the connection portion in the water supply line.

2. a filtered water line connecting the ultrafiltration device and the tank; a bypass line connecting the concentrated water line to a portion of the water supply line upstream of the electrodeionization device; The purified water supply system of claim 1 , further comprising: a bypass valve disposed in the bypass line.

3. a control unit that controls the pump, the water supply valve, and the bypass valve; The control unit a water flow control unit that opens the water supply valve, closes the bypass valve, and drives the pump; The purified water supply system according to claim 2 , further comprising a sterilization control unit that closes the water supply valve, opens the bypass valve, and drives the pump.

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