Pure water manufacturing device

Abstract

The present invention provides a pure water production device capable of realizing a sufficiently fast flow rate in each deionized water production device and capable of suppressing damage to the deionized water production device due to application of an excessive pressure. The purified water production device is provided with: a booster pump (3) disposed between deionized water production devices (1, 2); and a pressure gauge (4b) disposed between the booster pump (3) and the deionized water production device (1) located on the upstream side of the booster pump (3). At least one of the deionized water production devices (1) located on the upstream side of the booster pump (3) and the pressure gauge (4b) is an electroregenerative deionized water production device. At least one of the start and stop of the operation of the booster pump (3) is performed on the basis of the measured value of the pressure gauge (4b).

Description

Technical Field

[0001] This invention relates to a pure water production apparatus. Background Technology

[0002] Previously, in the manufacture of semiconductor devices and liquid crystal devices, highly purified water (including ultrapure water) with impurities such as organic matter, ions, particles, and bacteria removed was used as cleaning water. In particular, the requirements for water quality used in the cleaning process of electronic components containing semiconductor devices have been increasing year by year. Especially in recent years, there has been a strong demand for reducing boron. It is known that boron, a weakly acidic component, can be removed using reverse osmosis membrane devices (hereinafter referred to as "RO devices") and electro-regenerated deionized water production devices (hereinafter referred to as "EDI devices"). In recent years, as disclosed in Patent Document 1 (Japanese Patent Application Publication No. 2018-34103), methods for reducing the boron concentration in treated water have been put into practical use, including multi-stage treatment using multiple EDI devices connected in series, and multi-stage treatment combining EDI devices and other deionized water production devices (such as ion exchange resin devices, boron selective resin devices, etc.).

[0003] EDI units are more complex and expensive than ion exchange resin units, with more structural components. Therefore, to minimize the cost of pure water production, efforts are being made to increase the volume of water processed per unit time by using high flow rates. If the number of EDI units is increased when performing multi-stage treatment, the requirement for even higher flow rates becomes even more stringent.

[0004] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2018-34103 Summary of the Invention The technical problem that the invention aims to solve Increasing the flow rate of liquid through an EDI unit increases the pressure difference (water pressure differential) between the upstream and downstream sides of the EDI unit. In the case of producing pure water through multi-stage processing, increasing the flow rate of liquid through each of the multiple EDI units increases the water pressure differential for each unit. When achieving a high flow rate across all EDI units, considering the increased water pressure differential, a higher pressure needs to be applied to the liquid supplied to the upstream EDI unit than to the downstream EDI unit. That is, the desired water pressure differential for the downstream EDI unit needs to be added to the desired water pressure differential for the upstream EDI unit itself to supply a higher-pressure liquid to the upstream EDI unit. As a result, excessively high-pressure liquid is supplied to the upstream EDI unit, which may damage the unit. In particular, since EDI units typically have a structure with stacked plastic frames and relatively low pressure resistance, they are prone to damage when supplied with high-pressure liquids. Therefore, if a liquid with insufficient pressure is supplied to prevent damage to the upstream EDI unit, the downstream EDI unit cannot obtain a supply water pressure sufficient to achieve a sufficiently fast flow rate, and the cost-saving effect is reduced. It should be noted that the same problem arises in structures where other deionized water production devices (e.g., ion exchange resin devices, boron-selective resin devices, etc.) are installed instead of the downstream EDI unit.

[0005] Therefore, the object of the present invention is to provide a pure water manufacturing apparatus that can achieve a sufficiently fast flow rate in each deionized water manufacturing apparatus and can suppress damage to the deionized water manufacturing apparatus caused by applying excessively high pressure.

[0006] Technical solutions for solving technical problems This invention provides a pure water production apparatus comprising: a booster pump disposed between deionized water production devices; and a pressure gauge disposed between the booster pump and a deionized water production device located upstream of the booster pump. At least one of the deionized water production devices located upstream of the booster pump and the pressure gauge is an electro-regenerating deionized water production device. At least one of the start and stop of operation of the booster pump is based on the measurement value of the pressure gauge. It should be noted that this configuration also includes cases where other devices (e.g., ultraviolet oxidation devices, tanks, pumps) are disposed between the deionized water production devices in addition to the booster pump.

[0007] Alternatively, the booster pump may start operating when the pressure gauge reading increases from below the first set pressure value to above the first set pressure value during the shutdown of the booster pump.

[0008] Alternatively, during the operation of the booster pump, the pump may stop operating when the pressure gauge reading decreases from a value exceeding a second set pressure value to below the second set pressure value. Furthermore, during the shutdown of the booster pump, the pump may start operating when the pressure gauge reading increases from a value below a first set pressure value to above the first set pressure value, where the first set pressure value is a value greater than the second set pressure value.

[0009] The second set pressure value can be a value within the range of 0.00MPa to 0.05MPa.

[0010] The first set pressure value can be a value in the range of 0.02MPa to 0.1MPa.

[0011] Alternatively, during the shutdown of the booster pump, the booster pump may start operating when a set time has elapsed since the start of liquid delivery to the inlet of the booster pump.

[0012] The supply pump, located upstream of the deionized water manufacturing device at the forefront, can stop operating at the same time as the booster pump stops operating.

[0013] Pure water production can be carried out under the following conditions: the pressure difference of at least one of the plurality of deionized water production devices is greater than 0.20 MPa, and the sum of the pressure at the inlet of the desalination chamber of the electro-regenerative deionized water production device located upstream of the booster pump and the pressure at the outlet of the booster pump is greater than 1.5 times the pressure at the inlet of the desalination chamber of the electro-regenerative deionized water production device.

[0014] A switching valve is provided upstream of the deionized water manufacturing device on the upstream side of the booster pump. This valve switches between a water supply line that supplies water to the deionized water manufacturing device and a circulation line that returns the water to the upstream side of the supply pump. The supply pump is located upstream of the deionized water manufacturing device at the foremost stage. A switching valve is provided downstream of the deionized water manufacturing device on the downstream side of the booster pump. This valve switches between a water supply line that delivers treated water to the outside of the deionized water manufacturing device and another circulation line that returns the treated water to the upstream side of the supply pump. At least one of the switching valves may be a three-way valve.

[0015] Invention Effects According to the present invention, a sufficiently fast flow rate can be achieved in each deionized water manufacturing device, and damage to the deionized water manufacturing device caused by excessive pressure can be suppressed. Attached Figure Description

[0016] Figure 1This is a block diagram schematically illustrating a pure water production apparatus according to a first embodiment of the present invention.

[0017] Figure 2 This is a cross-sectional view schematically illustrating an example of the internal structure of a single-chamber EDI device.

[0018] Figure 3 This is a cross-sectional view schematically illustrating an example of the internal structure of a two-chamber desalination EDI device.

[0019] Figure 4 This is a block diagram schematically representing the pure water production apparatus of the first comparative example.

[0020] Figure 5 This is a block diagram schematically illustrating a pure water production apparatus according to a second embodiment of the present invention.

[0021] Figure 6 It means that it was used. Figure 5 The graph shows the relationship between the measured values ​​of each pressure gauge during the pure water production process in the pure water production device and the elapsed time.

[0022] Figure 7 It is a graph showing the relationship between the ratio of the actual flow rate of the EDI device to the standard flow rate and the pressure difference of the desalination chamber.

[0023] Figure 8 It is a schematic representation Figure 5 The desalination chamber of the EDI unit shown is a 2-chamber type.

[0024] Figure 9 This is a schematic cross-sectional view of the desalination chamber of a type 1 desalination chamber EDI device.

[0025] Figure 10 This is a block diagram schematically representing the pure water production apparatus of the second comparative example.

[0026] Figure 11 It means that it was used. Figure 10 The graph shows the relationship between the measured values ​​of each pressure gauge during the pure water production process in the pure water production device and the elapsed time.

[0027] Figure 12 This is a block diagram schematically illustrating a pure water production apparatus according to a second embodiment of the present invention.

[0028] Figure 13 This is a block diagram schematically illustrating a pure water production apparatus according to a third embodiment of the present invention.

[0029] Figure 14 This is a block diagram schematically illustrating a pure water production apparatus according to a fourth embodiment of the present invention. Detailed Implementation

[0030] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0031] [First Implementation Method] Figure 1 This is a block diagram schematically illustrating the basic structure of the pure water production apparatus according to the first embodiment of the present invention. In this embodiment, two deionized water production devices 1 and 2 are connected in series, and a booster pump 3 and a pressure gauge 4 are provided between these deionized water production devices 1 and 2. The upstream deionized water production device 1 is an EDI device (electro-regenerated deionized water production device). The downstream deionized water production device 2 can be an EDI device or other deionized water production devices (e.g., ion exchange resin device, boron selective resin device, etc.). However, in the following description, as an example, an example in which both the upstream deionized water production device 1 and the downstream deionized water production device 2 are EDI devices will be described.

[0032] EDI devices typically consist of a desalination chamber separated by a pair of ion exchange membranes between the anode and cathode, and the desalination chamber is filled with ion exchange resin. Figure 2The illustrated EDI devices 1 and 2 are of a single-chamber structure, each having a desalination chamber 13. A concentration chamber 24, a desalination chamber 13, and a concentration chamber 25 are sequentially arranged from the anode chamber 20 side between an anode chamber 20 (with an anode 18) and a cathode chamber 21 (with a cathode 19). The anode chamber 20 and concentration chamber 24 are adjacent to each other via a cation exchange membrane (CEM) 26; the concentration chamber 24 and desalination chamber 13 are adjacent to each other via an anion exchange membrane (AEM) 22; the desalination chamber 13 and concentration chamber 25 are adjacent to each other via a cation exchange membrane 23; and the concentration chamber 25 and cathode chamber 21 are adjacent to each other via an anion exchange membrane 27. The desalination chamber 13 is filled with ion exchange resin (typically including anion exchange resin (AER) and cation exchange resin (CER)). The anode chamber 20 is filled with cation exchange resin, and the cathode chamber 21 is filled with anion exchange resin. When a DC voltage is applied between the anode 18 and the cathode 19 in the EDI devices 1 and 2, the water to be treated is supplied to the desalination chamber 13, and the water is desalinated (deionized). As a result, the water with the ionic components removed is discharged from the desalination chamber 13 as treated water. In the desalination chamber 13, the anions separated by the anion exchange membrane 22 disposed on the anode 18 side move to the concentration chamber 24. The cations separated by the cation exchange membrane 23 disposed on the cathode 19 side move to the concentration chamber 25. Concentration chamber supply water is supplied to the concentration chambers 24 and 25, and the concentrated water is discharged. Electrode chamber supply water is supplied to the cathode chamber 21. The electrode chamber supply water supplied to the cathode chamber 21 is supplied to the anode chamber 20 after passing through the cathode chamber 21, and is discharged from the anode chamber 20 as electrode water. It should be noted that the cation exchange membrane 26 and the anion exchange membrane 27 can be omitted, and the concentration chambers 24 and 25 can also be used as electrode chambers (anode chamber and cathode chamber).

[0033] Figure 3 The EDI devices 1 and 2 illustrated herein are two-chamber desalination chambers 13 adjacent to each other, separated by anion exchange membranes (anion exchange membranes) 12. Between an anode chamber 20 (with an anode 18) and a cathode chamber 21 (with a cathode 19), a concentration chamber 24, two desalination chambers 13, and a concentration chamber 25 are sequentially arranged from the anode chamber 20 side. The desalination chamber 13 on the anode 18 side, located between the anode 18 and cathode 19, is divided by anion exchange membranes 12 and 22 and filled with ion exchange resin (at least a portion of which is composed of anion exchange resin). The desalination chamber 13 on the cathode 19 side is divided by anion exchange membrane 12 and a cation exchange membrane 23 and filled with ion exchange resin (at least a portion of which is composed of cation exchange resin). Other structures are similar to... Figure 2The structure of the desalination chamber 1 shown is the same, so its description is omitted. In these EDI devices 1 and 2, with a DC voltage applied between the anode 18 and the cathode 19, the water to be treated is supplied to the desalination chamber 13 on the anode 18 side for desalination (deionization) treatment. Then, it is moved to the desalination chamber 13 on the cathode 19 side for further desalination treatment. The water with the ionized components removed is discharged from the desalination chamber 13 on the cathode 19 side as treated water. The treatment in the concentration chambers 24 and 25, the cathode chamber 21, and the anode chamber 20 is similar to... Figure 2 The structure of the desalination chamber shown is the same as that of chamber 1, therefore description is omitted. It should be noted that the water flow direction can also be the same as... Figure 3 In contrast to the example shown, after the water to be treated is supplied to the desalination chamber 13 on the cathode 19 side for desalination (deionization) treatment, it is moved to the desalination chamber 13 on the anode 18 side for desalination treatment again, and the water with the ion components removed is discharged from the desalination chamber 13 on the anode 18 side as treated water.

[0034] exist Figure 1 In the pure water production apparatus of this embodiment shown, pressure gauge 4 is connected to the inlet side (upstream side) of booster pump 3. The tank 5 containing the water to be treated is connected to the upstream EDI device 1 (in... Figure 1 In the example shown, a supply pump 6 is located upstream of the first-stage EDI unit 1 and is positioned between the first-stage EDI unit 1 and the tank 5. Therefore, the tank 5, supply pump 6, first-stage EDI unit 1, pressure gauge 4, booster pump 3, and subsequent-stage EDI unit 2 are connected sequentially from the upstream side. Pure water is then discharged from the outlet of the subsequent-stage EDI unit 2. At least one of the start and stop of the booster pump 3's operation is based on the measurement value of the pressure gauge 4. In this specification, for convenience, the water supplied to the first-stage EDI unit 1 is referred to as treated water, and the water supplied to the subsequent-stage EDI unit 2 through the first-stage EDI unit 1 is referred to as intermediate treated water. The water after passing through all EDI units 1 and 2 is referred to as treated water or pure water.

[0035] The operation of the pure water production apparatus according to this embodiment will be explained. First, the supply pump 6 starts operating, supplying water to the upstream EDI device 1. Therefore, the reading on the pressure gauge 4 located downstream of the upstream EDI device 1 begins to rise. Then, while the booster pump 3 is stopped, when the reading on the pressure gauge 4 increases from below a predetermined value (first set pressure value) to above the first set pressure value, the booster pump 3 starts operating. Therefore, a sufficient amount of intermediate-treated water is supplied to the downstream EDI device 2. Thus, both the upstream EDI device 1 and the downstream EDI device 2 operate to produce pure water.

[0036] The effects of the pure water production apparatus of this embodiment described above will be explained. First, the pure water production apparatus of the first comparative example used for comparison with this embodiment will be described. Figure 4 In the first comparative example of the pure water production apparatus shown, similar to the first embodiment, a tank 5, a supply pump 6, a pre-stage EDI device 1, and a post-stage EDI device 2 are connected in series from the upstream side. However, a pressure gauge 4 and a booster pump 3 are not present. When the supply pump 6 of this comparative example of the pure water production apparatus starts operating, water is supplied from the tank 5 to the pre-stage EDI device 1 and the post-stage EDI device 2 to produce pure water. In this structure, in order to reduce processing costs, etc., it is assumed that the pressure difference (desired pressure difference) when the desired flow rate is achieved in each of the EDI devices 1 and 2 are X1 and X2, respectively. Then, the pressure of the water supplied to the pre-stage EDI device 1 is set as IP1, and the pressure of the pure water discharged from the outlet of the post-stage EDI device 2 is set as OP. Pressure OP is the desired pressure of the pure water produced and discharged during the stable operation of this pure water production apparatus. The pressure IP1 of the water supplied to the pre-stage EDI device 1 is obtained by calculating IP1 = OP + X1 + X2. That is, pressure IP1 is obtained by adding the pressure OP to the pressure difference X1 when achieving the desired flow rate of the upstream EDI device 1 and the pressure difference X2 when achieving the desired flow rate of the downstream EDI device 2, and it is a relatively high pressure. In practice, pressure losses in the path (water pipeline) also need to be considered, so pressure IP1 needs to be even higher. Thus, pressure IP1 is a very high pressure, which may damage the upstream EDI device 1. It should be noted that there are cases where the pressure difference X1 when achieving the desired flow rate of the upstream EDI device 1 is the same as the pressure difference X2 when achieving the desired flow rate of the downstream EDI device 2.

[0037] On the other hand, Figure 1 In the first embodiment of the present invention shown, a booster pump 3 is installed between the upstream EDI device 1 and the downstream EDI device 2. When the pressure of the intermediate treated water increases by Y through the booster pump 3, the pressure IP2 of the treated water supplied to the upstream EDI device 1 is obtained by calculating IP2 = OP + X1 + X2 - Y. This pressure IP2 is smaller than the pressure IP1 of the first comparative example, and the difference is the amount of pressure increase Y generated by the booster pump 3. Therefore, in this structure, the desired flow rates of EDI devices 1 and 2 can be achieved respectively to reduce processing costs, and the pressure IP2 of the treated water supplied to the upstream EDI device 1 can be suppressed to a low level to prevent damage to the upstream EDI device 1.

[0038] As described above, by installing a booster pump 3 between the upstream EDI unit 1 and the downstream EDI unit 2, the pressure IP2 of the treated water supplied to the upstream EDI unit 1 can be suppressed to a low level. However, both the supply pump 6 and the booster pump 3 require a certain amount of time from the start of operation to reaching a stable operating state. Therefore, the timing of starting the operation of the booster pump 3 after the supply pump 6 starts operating and the water flow to the upstream EDI unit 1 begins is important. When the supply pump 6 starts operating and the water flow to the upstream EDI unit 1 begins, but the booster pump 3 has not started operating, the pressure of the intermediate treated water supplied to the upstream side of the booster pump 3 increases. If the timing of starting the operation of the booster pump 3 is delayed, the pressure upstream of the booster pump 3 becomes too high, and therefore, the pressure applied to the upstream EDI unit 1 also becomes high, which may damage the EDI unit 1. On the other hand, if the booster pump 3 starts operating, the intermediate treated water that has already passed through the upstream EDI unit 1 is immediately transported to the downstream EDI unit 2 by the operation of the booster pump 3. As a result, the pressure of the intermediate treated water upstream of booster pump 3 decreases. If the timing of booster pump 3 starting operation is too early, the pressure of the intermediate treated water upstream of booster pump 3 becomes too low and turns into negative pressure, which may cause malfunction of booster pump 3 and damage to EDI unit 1. Consequently, sufficient water flow cannot be achieved in the downstream EDI unit 2, and good pure water production cannot be achieved.

[0039] If the timing of starting the booster pump 3 after the supply pump 6 has started operating and the water supply to the upstream EDI device 1 has begun is too early or too late, it may be difficult to produce good pure water, or it may cause damage to the EDI devices 1 and 2. Therefore, it is considered to start the booster pump 3 at a time when a constant time has elapsed since the supply pump 6 started operating. However, experiments have shown that the relationship between the elapsed time since the supply pump 6 started operating and the pressure change of the liquid in the booster pump 3 is not constant, and sometimes there will be deviations. Since the conditions when the pure water production device stops operating and the conditions of the device at the water delivery destination are not constant, even if it is desired to use a timer to adjust the timing of starting the booster pump 3 based on the elapsed time since the supply pump 6 started operating, there are cases where it is impossible to start the booster pump 3 at an appropriate time. Therefore, in the first embodiment of the present invention, a pressure gauge 4 for measuring the pressure of the intermediate treated water is arranged between the upstream EDI device 1 and the booster pump 3. And, the booster pump 3 is started when the measured value of the pressure gauge 4 reaches a predetermined value (first set pressure value). Therefore, regardless of the elapsed time from the start of operation of the supply pump 6, the boost pump 3 will start operating when the appropriate pressure is reached on the upstream side of the downstream EDI device 2 and the upstream side of the boost pump 3.

[0040] Furthermore, if the pressure of the intermediate treated water upstream of the booster pump 3 decreases for some reason after the booster pump 3 starts operating, it may cause malfunction of the booster pump 3 and negative pressure of the intermediate treated water as described above. Therefore, in this embodiment, during the operation of the booster pump 3, when the measured value of the pressure gauge 4 decreases from a value exceeding a predetermined value (second set pressure value) to below the second set pressure value, the operation of the booster pump 3 is stopped. Furthermore, at the same time as the operation of the booster pump 3 stops, the operation of the supply pump 6 also stops. In this way, by simultaneously stopping the booster pump 3 and the supply pump 6, the water supply to the EDI devices 1 and 2 is stopped, and the production of pure water is stopped. Therefore, it becomes possible to suppress pressure fluctuations at the time of stop, and it is possible to prevent the production of insufficiently high-quality pure water and damage to the EDI devices 1 and 2. In one example, it is preferable that the first set pressure value is a value in the range of 0.02 MPa to 0.1 MPa, and the second set pressure value is a value in the range of 0.00 MPa to 0.05 MPa, wherein the first set pressure value is greater than the second set pressure value. Furthermore, during normal operation shutdowns, simultaneously stopping both the booster pump 3 and the supply pump 6 can prevent damage to the device and ensure a stable shutdown. Thus, it is preferable that the start and stop of operation of the booster pump 3, located between the EDI devices 1 and 2, are based on the measurements from the pressure gauge 4. However, a structure where only the start and stop of operation of the booster pump 3 are based on the measurements from the pressure gauge 4 can also achieve certain benefits and is therefore preferred. These structures are also included within the scope of the present invention.

[0041] like Figure 1 As shown, when only one deionized water manufacturing device is provided upstream of the booster pump 3, this deionized water manufacturing device is EDI device 1, and a pressure gauge 4 is arranged between EDI device 1 and booster pump 3. Although not shown, assuming that multiple deionized water manufacturing devices are provided upstream of booster pump 3, at least one of these deionized water manufacturing devices, preferably the one closest to booster pump 3, is EDI device 1, and a pressure gauge 4 is arranged between EDI device 1 and booster pump 3. Although not shown, as a preferred embodiment, a structure can also be adopted in which tank 5, supply pump 6, RO device (not shown), upstream EDI device 1, pressure gauge 4, booster pump 3, and downstream EDI device 2 are connected sequentially from the upstream side.

[0042] [Second Implementation] Similar to the pure water manufacturing apparatus of the first embodiment, Figure 5The pure water production apparatus shown according to the second embodiment of the present invention includes a tank 5, a supply pump 6, a pre-stage EDI device 1, a pressure gauge 4b, a booster pump 3, and a post-stage EDI device 2. Furthermore, in this embodiment, inverters 7 are connected to both the supply pump 6 and the booster pump 3, and the acceleration time until a set frequency is reached is controlled to be 2 to 10 seconds, more preferably 2 to 6 seconds. In addition, in this embodiment of the pure water production apparatus, not only is pressure gauge 4b ​​connected to the downstream side of the pre-stage EDI device 1 and the upstream side of the booster pump 3, as in the first embodiment, but pressure gauge 4a is connected to the upstream side of the pre-stage EDI device 1, pressure gauge 4c is connected to the upstream side of the post-stage EDI device 2 and the downstream side of the booster pump 3, and pressure gauge 4d is connected to the downstream side of the post-stage EDI device 2. Furthermore, a water quality meter 8a is arranged on the upstream side of the pre-stage EDI device 1, between the supply pump 6 and the pressure gauge 4a. A water quality meter 8b is positioned downstream of the preceding EDI device 1 and upstream of the following EDI device 2, between the booster pump 3 and the pressure gauge 4c. A water quality meter 8c is positioned downstream of the following EDI device 2 and downstream of the pressure gauge 4d. It should be noted that the water quality conditions measured by water quality meter 8a differ significantly in cleanliness (the amount of impurities) from those measured by water quality meters 8b and 8c; therefore, water quality meters 8a and 8b and 8c are different types of water quality meters. Specifically, water quality meter 8a measures conductivity in units of μS / cm; a smaller value indicates greater cleanliness. On the other hand, water quality meters 8b and 8c measure resistivity in units of MΩ·cm; a larger value indicates greater cleanliness. In the pure water production apparatus of this embodiment, in addition to the water supply pipeline connecting the preceding EDI device 1 and the following EDI device 2 in series, a dual-system circulation pipeline is also provided. Specifically, a three-way valve 9a, serving as a switching valve, is installed upstream of the preceding EDI device 1, between the water quality meter 8a and the pressure gauge 4a, and a return path 10 is provided to allow the treated water to return from the three-way valve 9a to the tank 5. Furthermore, a three-way valve 9b, also serving as a switching valve, is installed downstream of the following EDI device 2, downstream of the water quality meter 8c, and a return path 11 is provided to allow the treated water to return from the three-way valve 9b to the tank 5. It should be noted that the following EDI device 2 can also be replaced with other deionized water production devices (e.g., ion exchange resin devices, boron selective resin devices, etc.). Preferably, at least one of the switching valves installed upstream of the preceding EDI device 1, between the water quality meter 8a and the pressure gauge 4a, and the switching valve installed downstream of the following EDI device 2, downstream of the water quality meter 8c, is a three-way valve, and more preferably both are three-way valves.

[0043] The method for producing pure water using the pure water production apparatus of this embodiment will be described. Figure 6 This indicates the relationship between the elapsed time since the start of the operation and the pressure values ​​measured by the pressure gauges 4a to 4d. First, the supply pump 6 is started. At this time, the three-way valve 9a cuts off the downstream path (water supply line) and opens the return path 10. Therefore, the treated water is circulated (step S1). This is called pre-circulation. The measurement value of the water quality gauge 8a immediately downstream of the supply pump 6 is continuously or intermittently checked (step S2). At the moment T1 when the specified water quality conditions (e.g., below 10 μS / cm) are reached, the three-way valve 9a is switched to allow the treated water to flow downstream. Therefore, water is supplied to the upstream EDI device 1 to desalinate the treated water (step S3). In parallel with the water supply to the upstream EDI device 1, the pressure of the pressure gauge 4b ​​on the inlet side (upstream side) of the booster pump 3 is continuously or intermittently measured (step S4). At the moment T2 when the measured value rises to the first set pressure value (e.g., 0.02 MPa), the booster pump 3 is started. Therefore, water is passed to the downstream EDI unit 2 to further desalinate the intermediate treated water (step S5). In this stage, the three-way valve 9b cuts off the downstream path (outlet of the pure water production unit) and opens the return path 11. Then, the measured value of the water quality meter 8c at the outlet side (downstream side) of the booster pump 3 is continuously or intermittently checked (step S6). At time T3 when a condition is met (e.g., 18 MΩ·cm or higher), the three-way valve 9b is switched to allow the treated water to flow downstream (step S7). Thus, pure water is produced using the pure water production unit of this embodiment. Afterwards, although... Figure 6 Not shown, but if the pressure reading of the pressure gauge 4b ​​on the inlet side (upstream side) of the booster pump 3 falls below the second set pressure value (e.g., 0.01 MPa), the operation of the supply pump 6 and the booster pump 3 will be stopped.

[0044] Thus, in the pure water production apparatus of this embodiment, when the measured value of the pressure gauge 4b ​​located at the inlet side of the booster pump 3 becomes equal to or greater than the first set pressure value, the booster pump 3 located between the upstream EDI device 1 and the downstream EDI device 2 begins operation. Afterwards, if the measured value of the pressure gauge 4b ​​falls below the second set pressure value, operation stops. However, as a variation of this embodiment, after starting the supply pump 6 to begin supplying water to the upstream EDI device 1 and supplying intermediate treated water to the inlet side of the booster pump 3—that is, after starting water supply from the upstream EDI device 1 to the downstream EDI device 2—the booster pump 3 can be started after a predetermined time has elapsed. This predetermined time is in the range of 1 to 10 seconds, more preferably in the range of 1 to 6 seconds. This predetermined time (the elapsed time until the booster pump 3 is started) and the acceleration time controlled by the inverter 7 are appropriately set according to the water flow rate, pipe diameter, etc. Specifically, if the processing flow rate (water flow rate) and the pipe diameter are large, it is preferable to adjust the time by extending the elapsed time until the booster pump 3 is started, and the acceleration time. For example, in a pipe diameter of 65A and 20m... 3 With a processing flow rate of approximately / h, it is preferable to set the elapsed time until the booster pump 3 is started to be approximately 2 seconds, and the inverter acceleration time to be approximately 5 seconds. According to this control method, the operation of the booster pump 3 can be controlled at an appropriate timing corresponding to changes in conditions during startup. These changes vary depending on the processing conditions of the stages preceding EDI devices 1 and 2, and the destination of the pure water delivered to the stages following EDI devices 1 and 2. In particular, extreme fluctuations in the pressure applied to the preceding EDI device 1 can be suppressed. Furthermore, in this embodiment, the operation of the supply pump 6 and the booster pump 3 is stopped when the pressure at the inlet side (upstream side) of the booster pump 3 decreases. Therefore, pressure fluctuations when the devices stop can also be suppressed.

[0045] In this embodiment, in addition to the water supply lines (supply lines) that supply water to EDI devices 1 and 2, a circulation line (return path 10) is also provided to return the treated water to tank 5. When starting the pure water production device, firstly, instead of supplying the treated water to the upstream EDI device 1, the treated water is circulated to tank 5. Then, the water quality of the treated water is checked using a water quality meter 8a located upstream of the upstream EDI device 1. After the water quality conditions are met, the circulation line is switched to the water supply line to begin pure water production. According to this structure, it is not necessary to check the water quality of the intermediate treated water that has passed through the upstream EDI device 1, and it is not necessary to set up a circulation line returning to tank 5 between the upstream EDI device 1 and the downstream EDI device 2. Moreover, stable startup can be achieved. In particular, if a three-way valve 9a is used to switch between the circulation line and the water supply line, the switching of the two lines can be performed completely synchronously. Because it can suppress timing deviations and degrees of opening and closing of the valve, it can suppress temporary flow and pressure fluctuations during the switching between the circulation pipeline and the water supply pipeline. The three-way valve 9a is preferably designed so that it does not become fully closed during switching operations, and all paths are connected at an intermediate opening. For example, the L3 type three-way valve manufactured by NIPPON VALVECONTROLS, INC. can be cited. Therefore, by minimizing the valve's long closing time, it is possible to prevent valve sticking and sluggish operation upon restarting.

[0046] A circulation pipeline (return path 11) is also provided to return the treated water from the downstream side of the subsequent EDI unit 2 back to tank 5. The decision to send treated water out of the pure water production unit or return it to tank 5 for circulation is made based on the water quality corresponding to the intended use of the pure water produced by this pure water production unit and the capacity of the tank (not shown) receiving the produced pure water. By also using a three-way valve 9b in this switching process, the same effect as described above can be achieved with the three-way valve 9a.

[0047] It should be noted that, although not shown, an overflow valve is located upstream of the upstream EDI unit 1 within the water supply line to release pressure during the temporary pressure increase at startup, thereby preventing excessive pressure from being applied to the upstream EDI unit 1. The overflow valve can discharge the treated water from the water supply line or return the treated water to a container such as tank 5.

[0048] [Effects of the Invention] EDI devices, due to the continuous electroregeneration enabled by direct current, have a higher flow rate (space velocity: SV) per unit resin volume compared to conventional ion exchange resin devices, typically ranging from 150 to 250 h⁻¹. -1The flow rate is approximately 0.09–0.15 MPa, with a pressure difference of around 0.09–0.15 MPa. In the case of multi-stage treatment using multiple EDI units for pure water production, increasing the flow rate of each EDI unit can improve treatment efficiency and thus reduce treatment costs. For example, as... Figure 7 As shown in the graph, if conventional EDI units are operated at a flow rate of approximately 1.3 to 1.5 times the standard flow rate (also known as Standard-Flow or Nominal-Flow) described in specifications such as those in catalogs, the pressure difference between each EDI unit increases to approximately 1.3 to 1.5 times. For example, if the processing flow rate of an EDI unit exceeds 1.2 times the standard flow rate, the pressure difference between the inlet and outlet of the desalination chamber is 0.2 MPa or more. Even though the specific values ​​vary to some extent depending on the individual EDI unit, the relationship remains unchanged: if the processing flow rate increases in this way, the pressure difference between the inlet and outlet of the desalination chamber also increases. Furthermore, when multiple EDI units are connected in series and the treated water is supplied from a single supply pump, high-pressure treated water needs to be supplied to the upstream EDI unit, and the pressure difference between this high-pressure treated water and the downstream EDI unit is added together.

[0049] According to "JIS B 8265 Structure of Pressure Vessels", the test pressure in the pressure test, under water pressure conditions, is specified as 1.5 times the operating pressure. Therefore, if a pressure exceeding 1.5 times the supply water pressure (operating pressure) during stable operation is applied by increasing the flow rate of the treated water supplied to the EDI unit, the pressure resistance of the EDI unit is exceeded, and the EDI unit may be damaged. As a condition for operating the EDI unit at high flow rates, a space velocity (SV) per unit volume of ion exchange resin in the desalination chamber is preferably 300–450 h⁻¹. -1 Water is circulated in a manner that allows for current density of 0.8–1.2 A / dm³. 2 The current is such that the pressure difference of the water in the desalination chamber is 0.2 to 0.3 MPa.

[0050] In this invention, a booster pump 3 is installed between the upstream EDI device 1 and the downstream EDI device 2 within the water supply pipeline. Therefore, since the pressure of the intermediate treated water increases as it flows through the water supply pipeline, it is not necessary for the treated water to have a high pressure, including the pressure difference between the two EDI devices 1 and 2, at the moment it is supplied to the upstream EDI device 1. However, in the structure where the booster pump 3 is installed between the upstream EDI device 1 and the downstream EDI device 2, when water is supplied to the EDI device at a high flow rate, if the time between the start-up of the supply pump 6 and the start-up of the booster pump 3 is late, the pressure of the treated water supplied to the upstream EDI device 1 may temporarily become too high. Conversely, if the time between the start-up of the supply pump 6 and the start-up of the booster pump 3 is too early, the pressure of the intermediate treated water at the inlet side of the booster pump 3 may be too low, potentially becoming a negative pressure. Therefore, the timing of starting the booster pump 3 after starting the supply pump 6 is important. The timing of starting the booster pump 3 can also be determined based on the elapsed time since the start of the supply pump 6. That is, the booster pump 3 can also be started when the time elapsed since the start of liquid delivery to the inlet of the booster pump 3 reaches a set time, even when the booster pump 3 has stopped operating. However, it is more preferable to determine the timing of starting the booster pump 3 based on the pressure at the inlet side of the booster pump 3. Therefore, it is possible to effectively produce pure water by passing water at a relatively fast flow rate while suppressing damage to the EDI devices 1 and 2, and to reduce processing costs.

[0051] Example [First Embodiment] The first embodiment of the present invention will be described. In this embodiment, a method is used... Figure 5 The pure water production apparatus of the second embodiment shown produces pure water. The EDI devices 1 and 2 of this embodiment are as follows... Figure 3 , 8 The schematic diagram shows a two-chamber desalination device with two adjacent desalination chambers 13 separated by an ion exchange membrane 12. Using two such two-chamber desalination EDI devices 1 and 2, a device is manufactured as follows... Figure 5 The pure water production apparatus shown. Both the upstream EDI unit 1 and the downstream EDI unit 2 set the spatial velocity SV of the desalination chamber 13 to a high flow rate condition, i.e., 320 [h]. -1 Set the current value to 1.0 [A / dm]. 2 The aforementioned steps S1 to S7 are performed. The space velocity SV is the value obtained by dividing the volume of the ion exchange resin contained in the desalination chamber 13 (which is substantially the same as the volume of the desalination chamber 13) by the flow rate of the liquid passing through the desalination chamber 13 (flow rate per unit time). The acceleration time of the inverter 7 connected to the booster pump 3 is set to 5 seconds. In this embodiment, the relationship between elapsed time and pressure from startup (when the supply pump 6 begins operation) is as follows: Figure 6 As shown.

[0052] When producing pure water, the supply pump 6 is started, and the treated water is circulated from the upstream side of the upstream EDI device 1 back to the tank 5 (step S1). The measurement value of the water quality meter 8a immediately downstream of the supply pump 6 is continuously or intermittently checked (step S2). When the measured value falls below the set value (e.g., 10 μS / cm) at time T1, the three-way valve 9a is switched to supply water to the upstream EDI device 1 (step S3). The measurement value of the pressure gauge 4b ​​at the inlet side (upstream side) of the booster pump 3 is continuously or intermittently checked (step S4). When the measured value rises to the first set pressure value (e.g., 0.02 MPa) at time T2, the booster pump 3 is started to supply water to the downstream EDI device 2 (step S5). The water quality meter 8c at the outlet (downstream) side of the booster pump 3 is continuously or intermittently checked (step S6). At time T3, when the measured value reaches or exceeds a set value (e.g., 18 MΩ·cm), the three-way valve 9b is switched to allow the treated water to flow downstream (step S7). Figure 6 As shown, the pressure of the water supplied to the upstream EDI unit 1 (measured by pressure gauge 4a) reaches its maximum value (0.28 MPa) near the start of operation of the booster pump 3, and then the measured value decreases to a stable state (0.25 MPa). It should be noted that if there is a time lag from the input of the start signal to the booster pump 3 to the start of water supply and discharge (until the motor speed fully increases), then the pressure of the water being treated reaches its maximum value after the start signal is input to the booster pump 3. Furthermore, in Figure 6In the example shown, pressure gauge 4a is measured intermittently (at 0.5-second intervals). A discrepancy (time lag) occurs between the timing when the actual pressure reaches its maximum value and the timing of the pressure gauge 4a measurement. As a result, the pressure gauge 4a reading appears to be at its maximum value after the booster pump 3 starts operating. However, theoretically, assuming these time lags can be ignored, the pressure of the water being treated reaches its maximum value before the booster pump 3 starts operating. If the booster pump 3 starts, the pressure of the water being treated gradually decreases. Thus, pure water production continues under a stable state with a constant pressure of the water being treated. That is, the maximum pressure (0.28 MPa) upstream of the upstream EDI device is suppressed to approximately 1.12 times the stable pressure (0.25 MPa). The possibility of EDI device 1 being damaged due to pressure rise at this level is very low. It should be noted that the pressure differential of the upstream EDI device 1 in this embodiment is 0.2 MPa, and the pressure differential of the downstream EDI device 2 is 0.19 MPa. It should be noted that if a resin with a relatively small particle size (e.g., a resin with an average particle size of 100 to 400 μm) is used as the ion exchange resin filling the desalination chamber 13, the pressure differential increases compared to the case where a resin with a large particle size (e.g., a resin with an average particle size greater than 400 μm) is used. Therefore, when using a resin with a relatively small particle size (e.g., a resin with an average particle size of 100 μm to 400 μm) as the ion exchange resin, it is particularly preferable to employ the present invention to prevent excessive pressure from being applied to the upstream EDI device 1.

[0053] exist Figure 8 In the case of the two-chamber desalination chamber type EDI device shown, the pressure difference between the treated water at the inlet of the desalination chamber 13 on the upstream side (anode side) and the treated water at the outlet of the desalination chamber 13 on the downstream side (cathode side) in the water flow direction is the water flow pressure difference. Furthermore, in the two-chamber desalination chamber type EDI device, the value Q / V1[h] is obtained by dividing the volume V1[L] of the ion exchange resin contained in one desalination chamber 13 by the flow rate Q[L / h] of the liquid passing through that desalination chamber 13. -1 The spatial velocity SV of the desalination chamber 13 is the value Q / V2[h] obtained by dividing the volume V2[L] of the ion exchange resin contained in another desalination chamber 13 by the flow rate Q[L / h] of the liquid passing through the desalination chamber 13. -1 ] represents the spatial velocity SV of the desalination chamber 13.

[0054] As EDI devices 1 and 2 in this embodiment, they can also use, for example Figure 2 , 9 The desalination chamber type 1 EDI device shown is not as... Figure 3 , 8The diagram shows a two-chamber desalination chamber type EDI device. In the case of a one-chamber desalination chamber type EDI device, the pressure difference between the treated water at the inlet and outlet of the single desalination chamber 13 is the flow pressure differential. Furthermore, the value Q / V[h] is obtained by dividing the volume V[L] of the ion exchange resin contained in the single desalination chamber 13 by the flow rate Q[L / h] of the liquid passing through the desalination chamber 13. -1 [Speed ​​SV] represents the space velocity. In this embodiment, even when using a pure water production apparatus employing an EDI device with a desalination chamber 1 type, the same effect as when using a pure water production apparatus employing an EDI device with a desalination chamber 2 type (achieving a fast flow rate while suppressing damage to EDI devices 1 and 2) can be obtained. Furthermore, in a pure water production apparatus using an EDI device with a desalination chamber 1 type, if a resin with a small particle size is used as the ion exchange resin filling the desalination chamber 13, a large water pressure differential occurs. Therefore, the present invention is particularly preferred to prevent excessive pressure from being applied to the upstream EDI device 1. For example, when the space velocity SV is 150 to 450 [h]... -1 In a desalination chamber 1-type EDI device operating under certain conditions, where at least a portion of the resin filling the desalination chamber 13 is made of resin with an average particle size of 100 to 400 μm, the present invention is particularly preferred to prevent excessive pressure from being applied to the upstream EDI device 1.

[0055] [Second Comparative Example] As a second comparative example compared to the first embodiment described above, using Figure 10 The pure water production apparatus shown produces pure water. This apparatus uses a combination of two switching valves 14a and 14b instead of three-way valve 9a, and a combination of two switching valves 14c and 14d instead of three-way valve 9b. In addition, it is... Figure 5 The pure water production apparatus shown has essentially the same structure. Furthermore, in this comparative example, the timing for initiating the operation of the booster pump 3 is changed from that of the aforementioned embodiment. Figure 11This indicates the relationship between the elapsed time from the start of the operation and the pressure values ​​measured by each pressure gauge 4a to 4d. Similar to the previous embodiment, the supply pump 6 is started (step S1), and the measurement value of the water quality meter 8a is continuously or intermittently checked (step S2). At time T1, when the measured value falls below the set value (e.g., 10 μS / cm), water is introduced into the upstream EDI device 1 (step S3). Then, the elapsed time from the start of water introduction into the upstream EDI device 1 is measured (step S4'). At time T2', when the elapsed time reaches 4 seconds, the booster pump 3 starts operating, introducing water into the downstream EDI device 2 (step S5). The measurement value of the water quality meter 8c at the outlet side of the booster pump 3 is continuously or intermittently checked (step S6). At time T3, when the measured value falls above the set value (e.g., 18 MΩ·cm), the treated water is allowed to flow downstream (step S7). During the stable operation of this comparative example, the relationship between the water pressure difference of each EDI device 1 and 2 and the pressure of the water to be treated supplied to each EDI device 1 and 2 is the same as that in the first embodiment described above, but as... Figure 11 As shown, the maximum pressure of the treated water supplied to the upstream EDI unit 1 (measured by pressure gauge 4a) is 0.48 MPa. This is 1.92 times the pressure of the treated water supplied under stable conditions when the upstream EDI unit 1 is operating (e.g., 0.25 MPa), which could potentially damage the EDI unit 1. It is believed that part of the reason for this increased pressure is the incomplete synchronization of the individual switching valves 14a-14d, and the time required for the booster pump 3 to start and reach stable operation (e.g., approximately 5 seconds). In contrast, it is considered that by shortening the time from the start of the supply pump 6 to the start of the booster pump 3, the pressure rise can be suppressed to a lower level. However, if this time is too short, the inlet side of the booster pump 3 will become negative, preventing proper water flow.

[0056] [Comparison between the first embodiment and the second comparative example] As described above, in the second comparative example, it is not easy to minimize the possibility of damaging EDI devices 1 and 2 while ensuring good water flow. This is because it is difficult to properly set the timing for starting the operation of the booster pump 3. However, as in the aforementioned embodiments of the present invention, if the start of the operation of the booster pump 3 is determined based on the measurement value of the pressure gauge 4b ​​rather than on elapsed time, the operation of the booster pump 3 starts at a good timing, and it is easier to produce good pure water while suppressing damage to EDI devices 1 and 2.

[0057] [Second Embodiment] Reference Figure 12 The pure water production apparatus according to a second embodiment of the present invention will be described. It can be used... Figure 5In the first embodiment of the pure water manufacturing apparatus shown, more specifically, one or more structural elements are provided between the upstream EDI device 1 and the downstream EDI device 2. In this embodiment, as an example, a pressure gauge 4e, a boron selective resin device (a deionized water manufacturing device of a different type than the EDI device) 17, an ultraviolet oxidation device 15, and an ion exchange resin device (a filter cartridge processor, a deionized water manufacturing device of a different type than the EDI device) 16 are sequentially arranged between the water quality meter 8b and the pressure gauge 4c immediately downstream of the pressure pump 3. Other than these, the structure is the same as that of the first embodiment, and therefore description is omitted. Using the pure water manufacturing apparatus of this embodiment, the same steps S1 to S7 as in the first embodiment are performed to produce pure water. During the stable state of pure water production, the pressure readings of gauge 4a are 0.31 MPa, 4b are 0.11 MPa, 4c are 0.26 MPa, 4d are 0.07 MPa, and the pressure reading of gauge 4e at the outlet of booster pump 3 is 0.46 MPa. At this time, the pressure difference of the upstream EDI device 1 is 0.2 MPa, and the pressure difference of the downstream EDI device 2 is 0.19 MPa.

[0058] The combined pressure of the treated water supplied under steady-state conditions when only the upstream EDI unit 1 is operating (e.g., 0.31 MPa) and the pressure of the treated water supplied under steady-state conditions when only the downstream unit of the booster pump 3 is operating (e.g., 0.46 MPa) is 0.31 MPa + 0.46 MPa = 0.77 MPa. This is 2.48 times the pressure of the treated water supplied under steady-state conditions when only the upstream EDI unit 1 is operating (e.g., 0.31 MPa). If treated water at this pressure were supplied to the EDI unit 1, the possibility of damage to the EDI unit 1 would be high. However, in this embodiment, the booster pump 3 increases the pressure of the liquid in the water supply line, thus reducing the pressure of the liquid supplied to the EDI unit 1 and suppressing damage to the EDI unit 1. It should be noted that the pure water production apparatus of this embodiment has a structure with four deionized water production units: the upstream EDI unit 1, the intermediate boron selective resin unit 17 and ion exchange resin unit 16, and the downstream EDI unit 2. In this structure, the operation of the booster pump 3 is controlled by the pressure gauge 4b ​​on the inlet side (upstream side) of the booster pump 3, which also helps to suppress damage to the upstream EDI device 1 caused by excessive pressure.

[0059] [Third Embodiment] Reference Figure 13 A pure water production apparatus according to a third embodiment of the present invention will be described. In the pure water production apparatus of this embodiment, when... Figure 5The pure water manufacturing apparatus of the first embodiment shown has the same booster pump 3, immediately downstream of the water quality meter 8b and pressure gauge 4d, with pressure gauge 4e, boron selective resin device (a deionized water manufacturing device of a different type than the EDI device) 17, ultraviolet oxidation device 15, and ion exchange resin device (filter cartridge processor, a deionized water manufacturing device of a different type than the EDI device) 16 arranged sequentially. However, pressure gauge 4c and the subsequent EDI device 2 are not provided. The structure other than this is the same as the pure water manufacturing apparatus of the first embodiment, so description is omitted. In the first embodiment, the EDI device 2 is set as the subsequent deionized water manufacturing device; in contrast, in this embodiment, the boron selective resin device 17 and the ion exchange resin device 16 are set as subsequent deionized water manufacturing devices. Using this pure water manufacturing apparatus, the same steps S1 to S7 as in the first embodiment are performed to produce pure water. The pressure readings of pressure gauge 4a, 4b, and 4d under steady-state conditions during pure water production are 0.31 MPa, 0.11 MPa, and 0.10 MPa, respectively. The pressure reading at the outlet of booster pump 3, measured by pressure gauge 4e, is 0.30 MPa. At this point, the differential pressure between the upstream EDI unit 1 and the downstream boron selective resin unit 17, ultraviolet oxidation unit 15, and ion exchange resin unit (filter cartridge processor) 16 is 0.20 MPa.

[0060] The combined pressure of the treated water supplied under steady-state conditions when only the upstream EDI unit 1 is operating (e.g., 0.31 MPa) and the pressure of the treated water supplied under steady-state conditions when only the downstream unit of the booster pump 3 is operating (e.g., 0.30 MPa) is 0.31 MPa + 0.30 MPa = 0.61 MPa. This is 1.96 times the pressure of the treated water supplied under steady-state conditions when only the upstream EDI unit 1 is operating (e.g., 0.31 MPa). If treated water at this pressure were supplied to the EDI unit 1, the possibility of damage to the EDI unit 1 would be high. However, in this embodiment, the booster pump 3 increases the liquid pressure within the water supply line, thus reducing the pressure of the liquid supplied to the EDI unit 1 and suppressing damage to the EDI unit 1.

[0061] [Fourth Embodiment] Reference Figure 14 The pure water production apparatus according to the fourth embodiment of the present invention will be described. In the pure water production apparatus of this embodiment, instead of Figure 5The EDI device 2, a downstream unit of the pure water production apparatus shown in the first embodiment, is equipped with a boron selective resin device 17. The structure is otherwise identical to that of the pure water production apparatus in the first embodiment, and therefore description is omitted. In the first embodiment, the EDI device 2 was configured as a downstream deionized water production apparatus; conversely, in this embodiment, the boron selective resin device 17 is configured as a downstream deionized water production apparatus. Using this pure water production apparatus, steps S1 to S7, identical to those in the first embodiment, are performed to produce pure water. During the pure water production, the pressure gauge 4a measured 0.31 MPa, the pressure gauge 4b ​​measured 0.11 MPa, the pressure gauge 4d measured 0.10 MPa, and the pressure gauge 4c at the outlet of the booster pump 3 and the inlet of the boron selective resin device 17 measured 0.18 MPa. At this time, the pressure difference of the upstream EDI device 1 is 0.2 MPa, and the pressure difference of the downstream boron selective resin device 17 is 0.08 MPa.

[0062] The combined pressure of the treated water supplied under steady-state conditions when only the upstream EDI unit 1 is operating (e.g., 0.31 MPa) and the pressure of the treated water supplied under steady-state conditions when only the downstream unit of the booster pump 3 is operating (e.g., 0.18 MPa) is 0.31 MPa + 0.18 MPa = 0.49 MPa. This is 1.58 times the pressure of the treated water supplied under steady-state conditions when only the upstream EDI unit 1 is operating (e.g., 0.31 MPa). If treated water at this pressure were supplied to the EDI unit 1, the possibility of damage to the EDI unit 1 would be high. However, in this embodiment, the booster pump 3 increases the liquid pressure within the water supply line, thus reducing the pressure of the liquid supplied to the EDI unit 1 and suppressing damage to the EDI unit 1.

[0063] The present invention has been described above with reference to the embodiments, but the present invention is not limited to the above embodiments. The structure and details of the present invention can be modified in various ways that can be understood by those skilled in the art within the scope of the present invention.

[0064] This application claims priority based on Japanese Patent Application No. 2023-100016, filed on June 19, 2023, the entire contents of which are incorporated herein by reference.

[0065] Symbol Explanation 1. 2EDI unit (electric regeneration deionized water production unit) 3. Booster Pump 4, 4a, 4b, 4c, 4d, 4e pressure gauges 5 cans 6. Supply pump 7 Inverter Water quality meters 8a, 8b, and 8c 9a, 9b Three-way valves 10, 11 Return Path 12 Ion exchange membranes 13 Desalination Chamber Switching valves 14a, 14b, 14c, and 14d 15. Ultraviolet Oxidation Device 16. Ion exchange resin unit (filter cartridge processor, deionized water production unit) 17. Boron selective resin unit (deionized water production unit) 18 Anode 19 Cathode 20 Anode Chamber 21 Cathode Chamber 22, 27 Anion exchange membranes 23, 26 Cation exchange membranes Concentration chambers 24 and 25.

Claims

1. A pure water production device, characterized in that, have: Booster pumps, which are configured between deionized water production units; and A pressure gauge is disposed between the booster pump and the deionized water manufacturing device located upstream of the booster pump. At least one of the deionized water manufacturing devices located upstream of the booster pump and the pressure gauge is an electro-regenerated deionized water manufacturing device. The start and stop of the operation of the booster pump are based on the measurement value of the pressure gauge.

2. The pure water manufacturing apparatus according to claim 1, wherein, During the shutdown of the booster pump, the booster pump starts operating when the pressure gauge reading increases from a value below the first set pressure value to a value above the first set pressure value.

3. The pure water manufacturing apparatus according to claim 1, wherein, During the operation of the booster pump, the booster pump stops operating when the pressure gauge reading decreases from a value exceeding the second set pressure value to below the second set pressure value.

4. The pure water manufacturing apparatus according to claim 3, wherein, When the booster pump stops operating, it starts operating when the pressure gauge reading increases from a value below the first set pressure value to a value above the first set pressure value. The first set pressure value is a value greater than the second set pressure value.

5. The pure water manufacturing apparatus according to claim 3 or 4, wherein, The second set pressure value is a value within the range of 0.00MPa to 0.05MPa.

6. The pure water production apparatus according to claim 2 or 4, wherein, The first set pressure value is a value within the range of 0.02MPa to 0.1MPa.

7. The pure water manufacturing apparatus according to claim 3, wherein, During the shutdown of the booster pump, the booster pump starts operating when a set time has elapsed since the start of liquid delivery to the inlet of the booster pump.

8. The pure water manufacturing apparatus according to any one of claims 3, 4 and 7, wherein, The supply pump located upstream of the deionized water manufacturing unit at the forefront stops operating at the same time as the booster pump stops operating.

9. The pure water manufacturing apparatus according to any one of claims 1, 2, 3, 4 and 7, wherein, The pure water production apparatus produces pure water under the following conditions: The differential pressure of at least one of the deionized water manufacturing devices is greater than 0.20 MPa, and the combined pressure of the inlet pressure of the desalination chamber of the deionized water manufacturing device located upstream of the booster pump and the outlet pressure of the booster pump is greater than 1.5 times the inlet pressure of the desalination chamber of the deionized water manufacturing device.

10. The pure water manufacturing apparatus according to any one of claims 1, 2, 3, 4 and 7, wherein, A switching valve is provided upstream of the deionized water manufacturing device on the upstream side of the booster pump. This valve switches between a water supply line that supplies water to the deionized water manufacturing device and a circulation line that returns the water to the upstream side of the supply pump. The supply pump is located upstream of the deionized water manufacturing device, which is the first stage of the device. A switching valve is provided on the downstream side of the deionized water manufacturing device, downstream of the booster pump, to switch between a water supply pipeline that delivers treated water to the outside of the deionized water manufacturing device and another circulation pipeline that returns the treated water to the upstream side of the supply pump. At least one of the switching valves is a three-way valve.

Images