Method for operating a deionized water production system and deionized water production system

Abstract

A method for operating a deionized water production system that produces deionized water from treated water using an electrodeionization water production device, has a water production mode in which treated water is passed to a desalination chamber of the electrodeionization water production device to obtain treated water without energizing the electrodeionization water production device, and a water production and regeneration mode in which treated water is passed to the desalination chamber to obtain treated water while energizing the electrodeionization water production device, and water is passed to at least one of a concentration chamber and an electrode chamber of the electrodeionization water production device, the water production and regeneration mode and the water production mode are alternately operated, and the electrodeionization water production device is operated in such a manner that the operation time of the water production mode is 1.5 to 6.4 times the operation time of the water production and regeneration mode.

Description

Technical Field

[0001] This invention relates to the operation method of a deionized water manufacturing system equipped with an electro-deionized water manufacturing apparatus, and to the deionized water manufacturing system itself. Background Technology

[0002] Deionized water production systems are known to deionize water by passing it through an ion exchanger, such as an ion exchange resin, via an ion exchange reaction. Such systems typically include a device with an ion exchanger, utilizing an ion exchange reaction based on the ion exchanger to produce deionized water (e.g., pure water). However, in devices with ion exchangers, the ion exchange groups of the ion exchanger become saturated as water is passed through, leading to a decrease in deionization performance. Therefore, a process to restore the deionization performance (hereinafter referred to as "regeneration") is required.

[0003] As a process for regenerating ion exchangers, known methods include periodically replacing ion exchangers with new ones, periodically regenerating ion exchangers using reagents such as acids or alkalis, and continuously regenerating ion exchangers using an electro-deionized water production device (also known as an EDI (Electro Deionization) device).

[0004] Since periodically replacing ion exchangers cannot produce deionized water during the replacement process, there is a technical problem of not being able to continuously produce deionized water. Furthermore, when producing deionized water by passing large volumes of treated water through the exchanger, ion exchanger replacements occur frequently, making it unsuitable for applications requiring large volumes of treated water to produce deionized water. Moreover, since periodically replacing ion exchangers involves using them only once, this increases waste and is therefore not preferred.

[0005] The method of regenerating ion exchangers using chemicals requires chemicals such as acids and alkalis. Since deionized water cannot be produced during the regeneration process, there is a technical problem that deionized water cannot be produced continuously.

[0006] Methods involving periodically replacing ion exchangers or using chemicals are used to continuously produce deionized water, for example, by preparing both active and standby ion exchangers and alternating between them. However, such methods lead to an increase in the number of devices used for filling ion exchangers and for injecting the chemicals required for regeneration.

[0007] An EDI device is structured with multiple anion exchange membranes and cation exchange membranes arranged between electrodes (anode and cathode) to form an electrode chamber, a concentration chamber, and a desalination chamber. Ion exchangers (anion exchangers and cation exchangers) are filled in the desalination chamber, etc. Water to be treated is supplied to the desalination chamber, while water (e.g., treated water, deionized water, etc.) is supplied to the electrode chamber and concentration chamber. The EDI device induces a current flow by applying a voltage between the electrodes, thereby causing a water dissociation reaction that generates hydrogen ions (H+). + ) and hydroxide ions (OH-) - The ion exchangers, through the exchange of ions with the ion exchangers attached to the desalination chamber, maintain deionization performance. Therefore, if an EDI device is used, the production of deionized water and the regeneration of the ion exchangers can be carried out continuously. For example, an EDI device is described in Patent Document 1.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: International Publication No. 2018 / 117035 Summary of the Invention

[0011] The technical problem that the invention aims to solve

[0012] To prevent the deterioration of deionized water (treated water) quality caused by reduced deionization performance, EDI units are typically powered continuously during operation. Therefore, deionized water production systems equipped with EDI units suffer from increased power consumption. Furthermore, during operation, treated water is supplied to the desalination chamber, and water is also supplied to the concentration and electrode chambers. Deionized water is produced in the desalination chamber, and concentrated water containing ions that have migrated from the desalination chamber is discharged from the concentration chamber, while electrode water is discharged from the electrode chamber. Therefore, EDI units also suffer from increased wastewater discharge.

[0013] The present invention was made to solve the technical problems of the background art as described above, and its purpose is to provide an operation method and a deionized water manufacturing system that can suppress the deterioration of the water quality of the treated water and reduce the power consumption and drainage of the electro-deionized water manufacturing device.

[0014] Technical solutions for solving technical problems

[0015] To achieve the above objectives, the present invention provides an operation method for a deionized water manufacturing system that uses an electro-deionized water manufacturing device to produce deionized water from treated water. This method includes a water intake mode and a water intake / regeneration mode.

[0016] In the water collection mode, when the electro-deionized water production device is not powered, the water to be treated is passed to the desalination chamber of the electro-deionized water production device to obtain treated water.

[0017] In the water collection and regeneration mode, while the electro-deionized water production device is powered on, the water to be treated is passed to the desalination chamber to obtain the treated water, and the water is also passed to at least one of the concentration chamber and electrode chamber of the electro-deionized water production device. The water collection and regeneration mode alternates with the water collection mode.

[0018] The electro-deionized water production device is operated such that the operating time of the water sampling mode is 1.5 to 6.4 times that of the operating time of the water sampling and regeneration mode.

[0019] Alternatively, it can be an operational method for a deionized water production system that uses an electro-deionization water production device to produce deionized water from treated water, which has a water intake mode and a water intake / regeneration mode.

[0020] In the water collection mode, when the electro-deionized water production device is not powered, the water to be treated is passed to the desalination chamber of the electro-deionized water production device to obtain treated water.

[0021] In the water collection and regeneration mode, while the electro-deionized water production device is powered on, the water to be treated is passed to the desalination chamber to obtain the treated water, and the water is also passed to at least one of the concentration chamber and electrode chamber of the electro-deionized water production device. The water collection and regeneration mode alternates with the water collection mode.

[0022] Let the daily load inflow be Q[meq], the processing flow rate of each desalination chamber be P[L / h], the total water operation time (both energized and de-energized) be T1[h], the conductivity of the water to be treated be C[μS / cm], the amount of regenerant generated due to energization in one day be G[meq], the total energization time per day be T2[h], the energizing current be I[A], and the Faraday constant be F[C / eq] = 96485, and satisfy the following conditions:

[0023] Q[meq]={(C-0.55)÷126.46}×P×T1

[0024] G[meq]=I×3600×T2÷F×1000

[0025] hour,

[0026] The electro-deionized water production apparatus is operated in the water intake mode and the water intake and regeneration mode in such a way that the load rate calculated by utilization load rate (%) = (Q÷G)×100 is in the range of 10% to 31%.

[0027] In other aspects, the deionized water manufacturing system of the present invention includes: an electro-deionized water manufacturing apparatus, which manufactures deionized water from water to be treated.

[0028] Power supply unit, which applies the required DC voltage to the electro-deionized water production apparatus; and

[0029] The control device is configured with a water sampling mode and a water sampling and regeneration mode. In the water sampling mode, when the electro-deionized water generating device is not powered, the water to be treated is passed to the desalination chamber of the electro-deionized water generating device to obtain treated water. In the water sampling and regeneration mode, the electro-deionized water generating device is powered while the water to be treated is passed to the desalination chamber to obtain the treated water, and the water is also passed to at least one of the concentration chamber and the electrode chamber of the electro-deionized water generating device. The water sampling and regeneration mode and the water sampling mode are operated alternately. The control device operates the electro-deionized water generating device such that the operating time of the water sampling mode is 1.5 times to 6.4 times the operating time of the water sampling and regeneration mode.

[0030] Alternatively, the deionized water manufacturing system may have: an electro-deionized water manufacturing device that produces deionized water from the water being treated;

[0031] Power supply unit, which applies the required DC voltage to the electro-deionized water production apparatus; and

[0032] The control device includes a water sampling mode and a water sampling / regeneration mode. In the water sampling mode, when the electro-deionized water generating device is not energized, the water to be treated is passed to the desalination chamber of the electro-deionized water generating device to obtain treated water. The device also includes a water sampling / regeneration mode, which alternates with the water sampling mode. In this mode, the electro-deionized water generating device is energized, and while the water to be treated is passed to the desalination chamber to obtain treated water, water is simultaneously passed to the concentration chamber and electrode chamber of the electro-deionized water generating device. In the absence of one of the following conditions, the control device sets the daily load inflow as Q[meq], the processing flow rate of each desalination chamber as P[L / h], the total water operation time (both during and without power supply) as T1[h], the conductivity of the water to be treated as C[μS / cm], the amount of regenerant generated due to power supply in one day as G[meq], the total power supply time per day as T2[h], the power supply current as I[A], and the Faraday constant as F[C / eq] = 96485, and satisfies the following conditions:

[0033] Q[meq]={(C-0.55)÷126.46}×P×T1

[0034] G[meq]=I×3600×T2÷F×1000

[0035] hour,

[0036] The electro-deionized water production apparatus is operated in the water intake mode and the water intake and regeneration mode in such a way that the load rate calculated by utilization load rate (%) = (Q÷G)×100 is in the range of 10% to 31%.

[0037] Invention Effects

[0038] According to the present invention, it is possible to suppress the deterioration of the water quality in the treated water and reduce the power consumption and drainage volume of the electro-deionized water production device. Attached Figure Description

[0039] Figure 1 This is a block diagram illustrating a structural example of the deionized water manufacturing system of the present invention.

[0040] Figure 2 It means Figure 1 A schematic diagram of a general structure example of an electro-deionized water manufacturing apparatus.

[0041] Figure 3 It means Figure 1 A schematic diagram of another general structural example of the electro-deionized water manufacturing apparatus shown.

[0042] Figure 4 It means Figure 1 A schematic diagram of another general structural example of the electro-deionized water manufacturing apparatus shown.

[0043] Figure 5 It is a graph showing the current efficiency and the conductivity of the treated water relative to the regeneration time of the ion exchanger.

[0044] Figure 6 This is a graph showing the water quality of the treated water under the first to fifth conditions and the comparative examples shown in Table 1 over a day.

[0045] Figure 7 This is a graph showing the power consumption over a day under the first to fifth conditions and in the comparative examples shown in Table 1.

[0046] Figure 8 This is a graph showing the relationship between the conductivity of the treated water and the ratio of the energizing time to the energizing stop time of the EDI device shown in Table 2.

[0047] Figure 9This is a graph showing the relationship between the power consumption reduction rate shown in Table 1 and the ratio of power-on time to power-off time of the EDI device shown in Table 2.

[0048] Figure 10 This is a graph showing the relationship between the conductivity of the treated water and the load rate shown in Table 3.

[0049] Figure 11 It is a graph showing the relationship between the power consumption reduction rate shown in Table 1 and the load rate shown in Table 3.

[0050] Figure 12 This is a graph showing the relationship between the conductivity of the treated water and the ratio of the energizing time to the energizing stop time of the EDI device shown in Table 2.

[0051] Figure 13 This is a graph showing the relationship between the conductivity of the treated water and the load rate shown in Table 3. Detailed Implementation

[0052] Next, the invention will be described using the accompanying drawings.

[0053] The inventors of this invention discovered that during the regeneration of the ion exchanger in an EDI device, the efficiency of electricity used for regeneration is improved when the salt form ratio of the ion exchanger is high. Therefore, in this embodiment, a method is proposed as follows: before the salt form ratio of the ion exchanger increases, deionized water is produced without power to the EDI device (no power supply); then, the EDI device is powered on and operated when the salt form ratio increases to a certain extent. Furthermore, the inventors of this invention discovered that compared to when the EDI device is powered on and operating continuously, by producing deionized water by only supplying the desalination chamber with treated water and not the concentration chamber and electrode chamber of the EDI device without power, it is possible to obtain deionized water of the same quality while reducing power consumption and wastewater volume. It should be noted that there is no reason why water cannot be supplied to the concentration chamber and electrode chamber of the EDI device when no power is supplied; water can be supplied to these chambers even when no power is supplied. Furthermore, "no power supply" as used here refers to a state where no water dissociation reaction occurs within the EDI device, and also includes situations where a weak voltage is applied between the electrodes to prevent ions from diffusing from the concentration chamber to the desalination chamber. For example, since the theoretical voltage required for water dissociation is 0.83V, this includes applying a voltage of less than 0.83V to each desalination chamber.

[0054] Figure 1 This is a block diagram illustrating a structural example of the deionized water manufacturing system of the present invention. Figure 2 It means Figure 1 A schematic diagram of a general structure example of an electro-deionized water manufacturing apparatus. Figure 3 and 4 It means Figure 1 A schematic diagram of another general structural example of the electro-deionized water manufacturing apparatus shown. Figures 2-4 It is the structure disclosed in the aforementioned patent document 1.

[0055] like Figure 1 As shown, the deionized water manufacturing system of the present invention includes: an electro-deionization water manufacturing apparatus (EDI apparatus) 1, which prepares deionized water from treated water; a power supply device 2, which applies a DC voltage to the EDI apparatus 1 required to maintain the performance of the deionized water; and a control device 3, which controls the operation of the entire deionized water manufacturing system. The treated water is pumped to the desalination chamber (D) of the EDI apparatus 1 via a pump (not shown), and treated water (deionized water) is produced through the desalination chamber (D). The conductivity of the treated water and the treated water is measured using known conductivity meters 4 (41 and 42) to determine the water quality. Additionally, the discharge rate (production rate) of the treated water from the desalination chamber (D) of the EDI apparatus 1 is measured using a known flow meter (cumulative flow meter) 5. The control device 3 is connected to the conductivity meters 4 and 5 via a known communication means, and transmits data on the conductivity of the treated water and the treated water, as well as data on the production rate of the treated water. Furthermore, the supply and stop of water to the concentration chamber C and electrode chamber E of the EDI unit 1 are controlled by using valve 6. The concentrated water discharged from the concentration chamber (C) and the electrode water discharged from the electrode chamber are drained into the drain tank 7, respectively.

[0056] Control device 3 is connected to power supply unit 2, pump, and valve 6 via known communication means, and is capable of controlling the operation of power supply unit 2, pump, and valve 6. Control device 3 controls the on / off switching of power supply unit 2, and controls the supply and stop of treated water to the desalination chamber (D) of EDI unit 1, and the supply and stop of treated water to the concentration chamber (C) and electrode chamber (E) of EDI unit 1 by using pump and valve 6. Furthermore, control device 3 includes a timer to control the operating time of EDI unit 1 in the two operating modes described later (water intake mode and water intake / regeneration mode). Communication between control device 3 and power supply unit 2, pump, valve 6, conductivity meter 4, and flow meter 5 can be achieved using either known wired or wireless communication means, and the communication standard can be any known standard.

[0057] The control device 3 can be implemented, for example, by a known PLC (Programmable Logic Controller). Alternatively, the control device 3 can be implemented by a known information processing device (computer) equipped with a CPU (Central Processing Unit), storage device, I / O interface, communication device, etc. The control device 3 executes a program pre-stored in the storage device via the processor of the PLC or information processing device, thereby realizing the operation method of the deionized water production system of the present invention.

[0058] Although Figure 1 Although not explicitly stated, in order to obtain deionized water with a sufficiently reduced impurity concentration, the deionized water production system of the present invention can include a reverse osmosis membrane device, which has a known reverse osmosis membrane (RO membrane) upstream of the EDI device 1. The deionized water production system can be a structure having multiple stages (e.g., two stages) of reverse osmosis membrane devices connected in series. In the case of two-stage reverse osmosis membrane devices, raw water stored in a storage tank or the like can be passed through the first-stage reverse osmosis membrane device, and this permeate can be passed through the second-stage reverse osmosis membrane device. The permeate from the second-stage reverse osmosis membrane device is then sent as treated water to the desalination chamber of the EDI device 1. The reverse osmosis membrane device can be, for example, any general reverse osmosis membrane structure used for the production of pure water.

[0059] like Figure 2 As shown, the structure of EDI device 1 is such that multiple sets of cation exchange membranes and anion exchange membranes are arranged between two electrodes (anode 11 and cathode 12). Figure 2 Electrode chambers 21 and 25, concentration chambers 22 and 24, and desalination chamber 23 are formed in two groups. Electrode chamber 21 (anode chamber) is formed by an anode 11 and a cation exchange membrane 31, and electrode chamber 25 (cathode chamber) is formed by a cathode 12 and an anion exchange membrane 34. Desalination chamber 23 is formed by an anion exchange membrane 32 and a cation exchange membrane 33, and the two concentration chambers 22 and 24 are formed to sandwich desalination chamber 23 in the middle. Concentration chamber 22 on the anode 11 side is formed by a cation exchange membrane 31 and anion exchange membrane 32, and concentration chamber 24 on the cathode 12 side is formed by a cation exchange membrane 33 and anion exchange membrane 34. Desalination chamber 23 is filled with an ion exchanger (MB) that is a mixture of cation and anion exchangers. It should be noted that ion exchangers may also be appropriately filled in electrode chambers 21 and 25 and concentration chambers 22 and 24.

[0060] In EDI device 1, the following structure also exists: Figure 3 As shown, multiple basic structures (unit groups) are arranged side by side between the anode 11 and the cathode 12. Each basic structure includes... Figure 2The concentration chamber 22, desalination chamber 23, and concentration chamber 24 are shown. At this time, adjacent concentration chambers can be shared between adjacent unit groups. Figure 3 This represents a structural example where N (N is an integer greater than or equal to 1) unit groups are arranged between the anode 11 and the cathode 12. Figure 3 In the EDI device 1 shown, the anode chamber 21 is filled with a cation exchanger (CER), the concentration chambers 22 and 24 and the cathode chamber 25 are filled with anion exchangers (AER), and the desalination chamber 23 is filled with a mixed ion exchanger (MB) of cation and anion exchangers. Furthermore, in Figure 3 The structure of the EDI device 1 shown is such that water is not supplied to the anode chamber 21 from the outside, but rather the outlet water of the cathode chamber 25 is supplied to the anode chamber 21.

[0061] In EDI device 1, the following structure also exists: Figure 4 As shown, two desalination chambers 26 and 27 are formed by placing an intermediate ion exchange membrane 36 between the two concentration chambers 22 and 24. Figure 4 In the EDI device 1 shown, desalination chamber 26 is filled with anion exchanger (AER), and desalination chamber 27 is filled with cation exchanger (CER). The treated water is passed through desalination chamber 27 and then through desalination chamber 26. The amounts of ion exchangers filled in the two desalination chambers 26 and 27 do not need to be the same. For example, it can be structured such that one desalination chamber is filled with both cation and anion exchangers, while the other chamber is filled with only cation exchangers. Alternatively, it can be structured such that one desalination chamber is filled with both cation and anion exchangers, while the other chamber is filled with only anion exchangers.

[0062] In addition, the EDI device 1 also has the following structure: an ion exchanger (anion exchange membrane 34 or cation exchange membrane 31) that does not separate the electrode chamber and the concentration chamber is provided, forming a combined chamber for both the concentration chamber and the electrode chamber.

[0063] In this configuration, in this embodiment, as the operating modes of the EDI device 1, there are two modes: a water sampling mode, in which the EDI device 1 is not energized, and the water to be treated is passed to the desalination chamber (D) to obtain treated water; and a water sampling and regeneration mode, in which the EDI device 1 is energized, and while the water to be treated is passed to the desalination chamber (D) to obtain treated water, the supply water is passed to the concentration chamber (C) and the electrode chamber (E) to regenerate the ion exchanger.

[0064] For example, when obtaining treated water with the water quality A1 for testing water use and drainage as specified in Japanese Industrial Standard (JIS K 0557), or the standard specification Type IV water quality (5 μS / cm (0.5 mS / m)) for reagent water as specified in ASTM standards, it is preferable to set the operating time of the water sampling mode to a range of 1.5 to 6.4 times that of the water sampling and regeneration mode. Furthermore, when obtaining treated water with even better water quality (1 μS / cm (0.1 mS / m)) as specified in the aforementioned Japanese Industrial Standard (JIS K 0557), it is more preferable to set the operating time of the water sampling mode to a range of 1.5 to 4.0 times that of the water sampling and regeneration mode. The lower limit of 1.5 times is determined by the power consumption reduction rate described later.

[0065] The operating times for the water intake mode and the water intake / regeneration mode can be determined as follows. For example, when the treated water has the water quality of the aforementioned standard specification (5 μS / cm (0.5 mS / m)), the operating times for the water intake mode and the water intake / regeneration mode are set such that the load rate calculated below is in the range of 10% to 31%. Alternatively, when the treated water has a better water quality (1 μS / cm (0.1 mS / m)) as specified in the aforementioned Japanese Industrial Standard (JIS K0557), the operating times for the water intake mode and the water intake / regeneration mode are set such that the load rate calculated below is in the range of 10% to 20%.

[0066] Load factor (%) = (Daily load inflow ÷ Daily regenerant generation due to power supply) × 100

[0067] Here, the daily load inflow is denoted as Q[meq], the treatment flow rate of each desalination chamber is denoted as P[L / h], the daily water operation time (the sum of the energized and non-energized periods) is denoted as T1[h], the conductivity of the treated water is denoted as C[μS / cm], the amount of regenerant generated due to energization in one day is denoted as G[meq], the total energization time per day is denoted as T2[h], the energizing current is denoted as I[A], and the Faraday constant is denoted as F[C / eq] = 96485.

[0068] Q[meq]={(C-0.55)÷126.46}×P×T1

[0069] G[meq]=I×3600×T2÷F×1000

[0070] calculate.

[0071] The daily load inflow Q is calculated by subtracting the conductivity of pure water from the conductivity of the treated water, converting the remaining conductivity to the limiting molar conductivity of NaCl, and then converting that to milliequivalents (meq). The daily regenerant generation G is calculated by converting the current value to electrical energy, and then converting that electrical energy to milliequivalents using the Faraday constant.

[0072] It should be noted that the water to be treated, preferably supplied to EDI unit 1, is water with a low concentration of components that may precipitate due to retention in the concentration chamber during operation in water intake mode. The water to be treated preferably has, for example, a silica concentration of 150 μg / L or less and a hardness (calcium and magnesium concentration) of 100 μg CaCO3 / L or less.

[0073] Incidentally, for example, intermittent operation of the EDI device 1 is also described in Japanese Patent Application Publication No. 2017-56384 (Patent Document 2). However, Patent Document 2 points out that if the operation of the EDI device 1 is stopped at the point when the required amount of treated water is obtained, the boron in the treated water increases, and proposes an operation method to maintain the boron removal rate. Therefore, the purpose of Patent Document 2 is not to reduce power consumption and wastewater while suppressing the deterioration of the treated water quality, as is the case with this invention, and is completely different from the operation method of the deionized water production system of this invention.

[0074] Example

[0075] Next, embodiments of the present invention will be described.

[0076] In this embodiment, Figure 1 In the deionized water manufacturing system shown, by controlling the operating time of the above-mentioned water sampling mode and water sampling and regeneration mode respectively, the deterioration of the water quality of the treated water can be suppressed, and the power consumption and drainage of the EDI device 1 can be reduced.

[0077] (First Embodiment)

[0078] In the first embodiment, a salt-type (chloride ion-type) ion exchange resin is prepared as the anion exchanger and filled into the desalination chamber of the EDI device 1 together with a regenerable cation exchange resin. Then, when the ion exchanger is regenerated by passing pure water through the desalination chamber, concentration chamber, and electrode chamber respectively, the proportion of current used in the discharge of chloride ions (regeneration of the ion exchange resin) relative to the amount of electricity energized to the EDI device 1 is calculated from the concentration of chloride ions discharged as concentrated water; that is, the current efficiency is plotted. Furthermore, the graph also shows the change in water quality of the treated water based on the conductivity measurement results.

[0079] Figure 5This is a graph showing the relationship between current efficiency and the conductivity of treated water relative to the regeneration time of the ion exchanger. Since the lower the amount of ions present, the lower the conductivity value, it can be said that the lower the conductivity value, the better the water quality.

[0080] like Figure 5 As shown, it can be seen that after the EDI device 1 is powered on, it can operate at a high efficiency of over 90% for about 2 hours, but the efficiency gradually decreases thereafter, falling below 50% after 10 hours. Furthermore, it can be confirmed that if the EDI device 1 is powered on, a conductivity of less than 1 μS / cm, representing the water quality of the treated water, can be achieved approximately 1 hour after the power-on begins.

[0081] Therefore, it can be seen that the current efficiency of EDI device 1 is high when operating with a high proportion of salt-type ion exchangers. Furthermore, it is known that if the operating time of EDI device 1 in a single power-on cycle, i.e., the water intake and regeneration mode, is set to 2 hours or more, operation can be performed with relatively good water quality (low conductivity). However, as mentioned above, since the current efficiency falls below 50% after 10 hours, it is preferable that the operating time of EDI device 1 in the water intake and regeneration mode is 10 hours or less.

[0082] (Second Embodiment)

[0083] In the second embodiment, the EDI device 1 was operated under the first to fifth conditions shown in Table 1 below, and the power consumption and the change in treated water quality were compared. In addition, Table 1 also shows the data for continuous operation of the EDI device 1 as a comparative example ("Comparison" in Table 1).

[0084] [Table 1]

[0085]

[0086] In the second embodiment, an EDI device (EDI-HF2-1000) 1 manufactured by Organo Corporation was used. The flow rate of treated water to the desalination chamber (D) was set to 2000 L / h, the flow rate of water supplied to the concentration chamber (C) in the water intake and regeneration mode was set to 240 L / h, and the flow rate of water supplied to the electrode chamber (E) was set to 20 L / h. Furthermore, in the water intake and regeneration mode, the EDI device 1 was set to operate at a constant current of 2.5 A DC current. Permeate water with a permeability of 2.5 ± 0.2 μS / cm, having passed through two series-connected reverse osmosis membrane units, was supplied to the desalination chamber (D) of the EDI device 1. Table 1 shows the daily operating data after the data stabilized following operation for more than two days under the first to fifth conditions described above.

[0087] Figure 6This is a graph showing the water quality of the treated water under the first to fifth conditions and the comparative examples shown in Table 1 over a day. Figure 7 This is a graph showing the power consumption over a day under the first to fifth conditions and in the comparative examples shown in Table 1.

[0088] like Figure 6 As shown, it can be confirmed that the conductivity of the treated water decreases when operating in water intake and regeneration mode, and increases when operating in water intake mode. Furthermore, it is observed that under the first condition of operating for only 5 hours per day, the conductivity increases significantly (water quality deteriorates significantly). On the other hand, under conditions three through five, the water quality shows a tendency to stabilize to some extent. However, it can be confirmed that the power consumption under condition five is higher than that in the comparison column shown in Table 1, which operates continuously for 24 hours in water intake and regeneration mode.

[0089] In conditions two through four, the total daily power-on time is equal (7 hours), but if... Figure 6 As shown, the water quality (conductivity) of the treated water changes over time, with the third condition stabilizing at the best water quality (lowest conductivity). Therefore, it is considered that the power-on time (operation time of the water intake and regeneration mode) should preferably be set to more than 2 hours each time. The fifth condition also requires a power-on time (operation time of the water intake and regeneration mode) of more than 2 hours each time, and the water quality (conductivity) of the treated water is also relatively good, but as mentioned above, the power consumption increases. The number of times the water intake and regeneration mode is operated per day differs between the third and fifth conditions: three times in the third condition and six times in the fifth condition. That is, it can be seen that even if the water quality is the same, increasing the number of times the water intake and regeneration mode is operated increases the drainage volume and power consumption.

[0090] Table 2 shows the ratio of power-on time to power-off time (no power-on time / power-on time) for the first to fifth conditions shown in Table 1 and the comparative example of EDI device 1. Table 3 shows the load rates mentioned above for the first to fifth conditions shown in Table 1 and the comparative example. Power-on time is the operating time in the water intake and regeneration mode, and no power-on time is the operating time in the regeneration mode.

[0091] [Table 2]

[0092] condition Power-on time: Stop time 1 1：3.8 2 1：2.4 3 1：2.4 4 1：2.4 5 1：0.8 Compare 1：0.0

[0093] [Table 3]

[0094] condition Load factor [%) 1 19.9 2 14.2 3 14.2 4 14.2 5 7.6 Compare 4.1

[0095] Figure 8 This is a graph showing the relationship between the conductivity of the treated water (maximum value in one day) and the ratio of the energized time to the energized-off time of the EDI device shown in Table 2 (no energization time / energized time). Figure 9 It is a graph showing the relationship between the power consumption reduction rate shown in Table 1 and the ratio of power-on time to power-off time (no power-on time / power-on time) of EDI device 1 shown in Table 2.

[0096] It should be explained that Figure 8 and Figure 9 And the following Figures 10-13 The curve represents the case where the approximate curve is extended using the maximum value calculated under the conditions shown in Tables 1 to 3.

[0097] from Figure 8 It is understood that, for example, in order to obtain treated water with a conductivity of 1 μS / cm as described above, the ratio of the energizing time to the energizing stop time (no energizing time / energizing time) of the EDI device 1 is preferably 4.0 times or less. Furthermore, as... Figure 9 As shown, in order to reduce the power consumption of EDI device 1 to 0% or less, that is, to further reduce power consumption than the above comparative example, it is preferable that the ratio of power-on time to power-off time (no power-on time / power-on time) of EDI device 1 is 1.5 times or more.

[0098] Figure 10 This is a graph showing the relationship between the conductivity of the treated water and the load rate shown in Table 3. Figure 11 It is a graph showing the relationship between the power consumption reduction rate shown in Table 1 and the load rate shown in Table 3. Figure 12 This is a graph showing the relationship between the conductivity of the treated water and the ratio of the energizing time to the energizing stop time (no energizing time / energizing time) of the EDI device shown in Table 2. Figure 13 This is a graph showing the relationship between the conductivity of the treated water and the load rate shown in Table 3. Figure 12 Indicates further extension from Figure 8 The curve shown is an approximate curve starting from the maximum value of the graph. Figure 13 Indicates further extension from Figure 10 The curve shown is an approximate curve starting from the maximum value of the graph.

[0099] Depend on Figure 10 It is understood that, for example, in order to obtain treated water with a conductivity of 1 μS / cm as described above, a loading rate of 20% or less is preferred. Furthermore, from... Figure 11 It is understood that in order to reduce the power consumption of EDI device 1 to 0%, that is, to further reduce power consumption than the above comparative example, the load rate is preferably 10% or more.

[0100] from Figure 12 It is understood that, for example, in order to obtain treated water with a conductivity of 5 μS / cm as described above, the ratio of the energizing time to the energizing stop time (no energizing time / energizing time) of the EDI device 1 is preferably 6.4 times or less. Furthermore, from Figure 13It is understood that, for example, in order to obtain treated water with a conductivity of 5 μS / cm as described above, it is preferable to have a load rate of 31% or less.

[0101] That is, when obtaining treated water with a conductivity of 5 μS / cm as described above, it is preferable to set the operating time (no-energization time) of the water sampling mode to 1.5 to 6.4 times the operating time (energization time) of the water sampling and regeneration mode. Furthermore, when obtaining treated water with a conductivity of 1 μS / cm as described above, it is preferable to set the operating time (no-energization time) of the water sampling mode to 1.5 to 3.8 times the operating time (energization time) of the water sampling and regeneration mode, and more preferably to a range of 1.5 to 2.4 times.

[0102] Alternatively, when obtaining treated water with a conductivity of 5 μS / cm, it is preferable to set the water intake mode (no power supply) and the water intake / regeneration mode (power supply) in a manner where the load rate is in the range of 10% to 31%. Furthermore, when obtaining treated water with a conductivity of 1 μS / cm, it is preferable to set the water intake mode (no power supply) and the water intake / regeneration mode (power supply) in a manner where the load rate is in the range of 10% to 20%.

[0103] As described above, according to the present invention, a water sampling mode and a water sampling and regeneration mode are provided. In the water sampling mode, the water to be treated is passed to the desalination chamber (D) to obtain treated water without powering on the EDI device 1. In the water sampling and regeneration mode, the water to be treated is passed to the desalination chamber while the EDI device 1 is powered on to obtain treated water, and the supply water is passed to the concentration chamber (C) and the electrode chamber (E) to maintain the deionization performance of the ion exchanger. The operating time (no power-on time) of the water sampling mode is set to a range of 1.5 to 6.4 times that of the operating time (power-on time) of the water sampling and regeneration mode. Alternatively, if the water sampling mode (no power-on) and the water sampling and regeneration mode (power-on) are set in such a way that the load rate is in the range of 10% to 31%, the power consumption and drainage volume of the EDI device 1 can be reduced while suppressing the deterioration of the treated water quality.

[0104] In order to obtain treated water with better quality (conductivity of 1 μS / cm as mentioned above), the operating time of the water sampling mode (no power supply time) can be set to a range of 1.5 to 4.0 times that of the operating time of the water sampling and regeneration mode (power supply time), or the water sampling mode (no power supply) and the water sampling and regeneration mode (power supply) can be set in such a way that the load rate is in the range of 10% to 20%.

Claims

1. A method for operating a deionized water manufacturing system, comprising a method for producing deionized water from treated water using an electro-deionization water manufacturing device, wherein the method for operating the deionized water manufacturing system includes a water intake mode and a water intake / regeneration mode. In the water collection mode, when the electro-deionized water production device is not powered, the water to be treated is passed to the desalination chamber of the electro-deionized water production device to obtain treated water. In the water collection and regeneration mode, while the electro-deionized water production device is powered on, the water to be treated is passed to the desalination chamber to obtain the treated water, and the water is also passed to at least one of the concentration chamber and electrode chamber of the electro-deionized water production device. The water collection and regeneration mode alternates with the water collection mode. The electro-deionized water production device is operated such that the operating time of the water sampling mode is 1.5 to 6.4 times that of the operating time of the water sampling and regeneration mode.

2. A method for operating a deionized water manufacturing system, comprising a method for producing deionized water from treated water using an electro-deionization water manufacturing device, wherein the method for operating the deionized water manufacturing system includes a water intake mode and a water intake / regeneration mode. In the water collection mode, when the electro-deionized water production device is not powered, the water to be treated is passed to the desalination chamber of the electro-deionized water production device to obtain treated water. In the water collection and regeneration mode, while the electro-deionized water production device is powered on, the water to be treated is passed to the desalination chamber to obtain the treated water, and the water is also passed to at least one of the concentration chamber and electrode chamber of the electro-deionized water production device. The water collection and regeneration mode alternates with the water collection mode. Let the daily load inflow be Q[meq], the processing flow rate of each desalination chamber be P[L / h], the total water operation time (both during and without power supply) be T1[h], and the conductivity of the water to be treated be C[…]. μ Let G[meq] be the amount of regenerant generated due to daily energization, T2[h] be the total daily energization time, I[A] be the energizing current, and Faraday's constant be F[C / eq] = 96485, and satisfy the following conditions: Q[meq]={(C-0.55)÷126.46}×P×T1 G[meq]=I×3600×T2÷F×1000 hour, The electro-deionized water production apparatus is operated in the water intake mode and the water intake and regeneration mode in such a way that the load rate calculated by utilization load rate (%) = (Q÷G)×100 is in the range of 10% to 31%.

3. The method of operating the deionized water production system according to claim 1 or 2, wherein, The water extraction and regeneration mode operates for more than 2 hours each time.

4. The method of operating the deionized water production system according to claim 1 or 2, wherein, The permeate water after passing through the reverse osmosis membrane device is used as the treated water and passed into the desalination chamber.

5. The method of operating the deionized water production system according to claim 1 or 2, wherein, The concentration of ionic silica in the treated water is 150. μ g / L or less, hardness 100 μ Below g CaCO3 / L.

6. A deionized water production system, comprising: An electro-deionized water manufacturing device that produces deionized water from water being treated; Power supply unit, which applies the required DC voltage to the electro-deionized water production apparatus; and The control device is configured with a water sampling mode and a water sampling and regeneration mode. In the water sampling mode, when the electro-deionized water generating device is not powered, the water to be treated is passed to the desalination chamber of the electro-deionized water generating device to obtain treated water. In the water sampling and regeneration mode, the electro-deionized water generating device is powered while the water to be treated is passed to the desalination chamber to obtain the treated water, and the water is also passed to at least one of the concentration chamber and the electrode chamber of the electro-deionized water generating device. The water sampling and regeneration mode and the water sampling mode are operated alternately. The control device operates the electro-deionized water generating device such that the operating time of the water sampling mode is 1.5 times to 6.4 times the operating time of the water sampling and regeneration mode.

7. A deionized water production system, comprising: An electro-deionized water manufacturing device that produces deionized water from water being treated; Power supply unit, which applies the required DC voltage to the electro-deionized water production apparatus; and The control device is configured with a water sampling mode and a water sampling and regeneration mode. In the water sampling mode, when the electro-deionized water production device is not powered, the water to be treated is passed to the desalination chamber of the electro-deionized water production device to obtain treated water. In the water sampling and regeneration mode, the electro-deionized water production device is powered on while the water to be treated is passed to the desalination chamber to obtain treated water, and the water is also passed to at least one of the concentration chamber and electrode chamber of the electro-deionized water production device. The control device defines the daily load inflow as Q[meq], the treatment flow rate of each desalination chamber as P[L / h], the total water flow operation time during the day when powered on and when not powered as T1[h], and the conductivity of the water to be treated as C[…]. μ Let G[meq] be the amount of regenerant generated due to daily energization, T2[h] be the total daily energization time, I[A] be the energizing current, and Faraday's constant be F[C / eq] = 96485, and satisfy the following conditions: Q[meq]={(C-0.55)÷126.46}×P×T1 G[meq]=I×3600×T2÷F×1000 hour, The electro-deionized water production apparatus is operated in the water intake mode and the water intake and regeneration mode in such a way that the load rate calculated by utilization load rate (%) = (Q÷G)×100 is in the range of 10% to 31%.

8. The deionized water production system according to claim 6 or 7, wherein, The water extraction and regeneration mode operates for more than 2 hours each time.

9. The deionized water production system according to claim 6 or 7, wherein, The deionized water production system also includes a reverse osmosis membrane device, which uses the permeate after passing through the reverse osmosis membrane as the treated water to be passed into the desalination chamber.

10. The deionized water production system according to claim 6 or 7, wherein, The concentration of ionic silica in the treated water is 150. μ g / L or less, hardness 100 μ Below g CaCO3 / L.

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