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

Abstract

An operating method for a deionized water manufacturing system, using an electric deionized water manufacturing device to produce deionized water from treated water, includes: a water intake mode, in which, when the electric deionized water manufacturing device is not energized, water to be treated is passed to the desalination chamber of the aforementioned electric deionized water manufacturing device to obtain treated water; and a water intake and regeneration mode, which alternates with the water intake mode, in which the electric deionized water manufacturing device is energized while water to be treated is passed to the aforementioned desalination chamber to obtain treated water, and water is simultaneously passed to at least one of the concentration chamber and electrode chamber of the electric deionized water manufacturing device; and the electric deionized water manufacturing device is operated such that the operating time of the water intake mode is 1.5 to 6.4 times that of the operating time of the water intake and regeneration mode.

Description

[Technical Field]

[0001] The present invention relates to an operation method of a deionized water manufacturing system having an electric deionized water manufacturing apparatus and a deionized water manufacturing system. [Previous Technology]

[0002] Deionized water production systems are known in which water to be treated is passed through an ion exchanger such as an ion exchange resin and deionized by an ion exchange reaction. Such systems generally have a device with an ion exchanger and use an ion exchange reaction performed by the ion exchanger to produce deionized water (e.g., pure water). However, in devices with ion exchangers, as water to be treated is passed through, the ion exchange groups of the ion exchanger become saturated and the deionization performance decreases, so a process to restore the deionization performance (hereinafter referred to as "regeneration") must be performed.

[0003] As a process for regenerating ion exchangers, there are known methods such as periodically replacing ion exchangers with new ones, periodically regenerating ion exchangers using agents such as acids or alkalis, and continuously regenerating ion exchangers using an electric deionized water production device (also known as an EDI (ElectroDeionization) device).

[0004] The method of periodically replacing ion exchangers has the following problems: deionized water cannot be produced during the replacement operation, so continuous production of deionized water is not possible. Furthermore, when producing deionized water by passing a large flow rate of treated water through the system, the replacement of ion exchangers occurs more frequently, making it unsuitable for applications involving the production of deionized water from large flow rates of treated water. Moreover, the method of periodically replacing ion exchangers involves discarding them after use, leading to increased waste and thus making it less than ideal.

[0005] The method of regenerating ion exchangers using reagents has the following problems: it requires reagents such as acids and bases, and deionized water cannot be produced during the regeneration process, so it is impossible to continuously produce deionized water.

[0006] If it is desired to continuously produce deionized water by periodically replacing ion exchangers or by using chemicals, one might consider, for example, preparing ion exchangers for current use and for future use and switching between them alternately. However, such a method would increase the number of devices for filling ion exchangers and devices for injecting chemicals required for regeneration.

[0007] An EDI device is configured to form an electrode chamber, a concentration chamber, and a desalination chamber by arranging multiple anion exchange membranes and cation exchange membranes between electrodes (anode and cathode), and to fill the desalination chamber with ion exchangers (anion exchangers and cation exchangers). The desalination chamber is supplied with water to be treated, and the electrode chamber and concentration chamber are supplied with water (e.g., water to be treated, deionized water, etc.). The EDI device initiates a water dissociation reaction by applying a voltage and allowing current to flow between the electrodes, generating hydrogen ions (H+) and hydroxide ions (OH-), which then exchange with ions attached to the ion exchangers in the desalination chamber, thereby maintaining deionization performance. Therefore, by using an EDI device, the production of deionized water and the regeneration of ion exchangers can be carried out continuously. For example, an EDI device has been described in Patent Document 1. [Prior Art Documents] [Patent Documents]

[0008] [Patent Document 1] International Publication No. 2018 / 117035 [Summary of the Invention]

[0009] [The problem the invention aims to solve]

[0010] EDI devices are typically kept powered during operation to prevent the deterioration of deionized water (treated water) quality due to reduced deionization performance. Therefore, deionized water production systems equipped with EDI devices suffer from increased power consumption. Furthermore, during operation, treated water is supplied to the desalination chamber, as well as to the concentration chamber and electrode chamber. Thus, while deionized water is being produced in the desalination chamber, concentrated water containing ions that have migrated from the desalination chamber is discharged from the concentration chamber, and electrode water is discharged from the electrode chamber. Therefore, EDI devices also suffer from increased wastewater discharge.

[0011] This invention addresses the problems existing in the prior art described above, and aims to provide an operation method and system for a deionized water production system that inhibits the deterioration of treated water quality and reduces power consumption and wastewater discharge in electric deionized water production devices. [Means for Solving the Problems]

[0012] To achieve the above objective, the operation method of the deionized water manufacturing system of the present invention is an operation method of a deionized water manufacturing system, which uses an electric deionized water manufacturing device to manufacture deionized water from treated water, comprising: a water intake mode, in which the treated water is fed to the desalination chamber of the electric deionized water manufacturing device to obtain treated water when the electric deionized water manufacturing device is not powered; and a water intake and regeneration mode, which alternates with the water intake mode, in which the treated water is fed to the desalination chamber to obtain the treated water while the electric deionized water manufacturing device is powered, and at the same time the water is fed to at least one of the concentration chamber and the electrode chamber of the electric deionized water manufacturing device; and the electric deionized water manufacturing device is operated in such a way that the operation time of the water intake mode is 1.5 times to 6.4 times the operation time of the water intake and regeneration mode.

[0013] Alternatively, a method of operating a deionized water manufacturing system, using an electric deionized water manufacturing device to manufacture deionized water from treated water, comprising: a water intake mode, in which, when the electric deionized water manufacturing device is not energized, the treated water is passed to the desalination chamber of the electric deionized water manufacturing device to obtain treated water; and a water intake and regeneration mode, which alternates with the water intake mode, in which the electric deionized water manufacturing device is energized while the treated water is passed to the desalination chamber to obtain the treated water, and water is simultaneously passed to at least one of the concentration chamber and the electrode chamber of the electric deionized water manufacturing device; and the electric deionized water manufacturing device is operated in the water intake mode and the water intake and regeneration mode with a load rate in the range of 10-31%, the load rate being calculated as follows. 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 (with and without power) be T1[h], the conductivity of the treated water be C[μS / cm], the amount of regenerant generated by power in one day be G[meq], the total power-on time per day be T2[h], the current be I[A], the Faraday constant be F[C / eq]=96485, and Q[meq]={(C-0.55)÷126.46}×P×T1 G[meq]=I×3600×T2÷F×1000, then the load rate (%)=(Q÷G)×100.

[0014] On the other hand, the deionized water manufacturing system of the present invention comprises: an electric deionized water manufacturing apparatus that manufactures deionized water from treated water; a power supply device that applies a required DC voltage to the electric deionized water manufacturing apparatus; and a control device that sets a water intake mode and a water intake and regeneration mode that alternates with the water intake mode; the water intake mode is used to obtain treated water by passing the treated water to the desalination chamber of the electric deionized water manufacturing apparatus when the electric deionized water manufacturing apparatus is not powered; the water intake and regeneration mode is used to obtain treated water by passing the treated water to the desalination chamber while the electric deionized water manufacturing apparatus is powered, and simultaneously passing water to at least one of the concentration chamber and the electrode chamber of the electric deionized water manufacturing apparatus; and the control device operates the electric deionized water manufacturing apparatus such that the operating time of the water intake mode is 1.5 to 6.4 times the operating time of the water intake and regeneration mode.

[0015] Alternatively, a deionized water manufacturing system may be provided, comprising: an electric deionized water manufacturing apparatus that manufactures deionized water from treated water; a power supply device that applies a required DC voltage to the electric deionized water manufacturing apparatus; and a control device that sets a water intake mode and a water intake / regeneration mode that alternates with the water intake mode; the water intake mode is used when the electric deionized water manufacturing apparatus is not powered, by passing the treated water to the desalination chamber of the electric deionized water manufacturing apparatus to obtain treated water; the water intake / regeneration mode is used when the electric deionized water manufacturing apparatus is powered, by passing the treated water to the desalination chamber to obtain treated water, and simultaneously passing water to at least one of the concentration chamber and the electrode chamber of the electric deionized water manufacturing apparatus; and the control device operates the electric deionized water manufacturing apparatus in the water intake mode and the water intake / regeneration mode with a load rate in the range of 10-31%, the load rate being calculated as follows. Let the daily load inflow be Q[meq], the processing flow rate of each desalination chamber be P[L / h], the total water flow time (with and without power) be T1[h], the conductivity of the treated water be C[μS / cm], the daily regenerant production due to power supply be G[meq], the total power supply time per day be T2[h], the current be I[A], the Faraday constant be F[C / eq] = 96485, and Q[meq] = {(C-0.55)÷126.46}×P×T1 G[meq] = I×3600×T2÷F×1000, then the load rate (%) = (Q÷G)×100. [Effects of the Invention]

[0016] According to the present invention, the deterioration of the water quality of the treated water can be suppressed and the power consumption and drainage of the electric deionized water production device can be reduced.

Implementation Method

[0018] The present invention will be described below using drawings. 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 better when the salt content of the ion exchanger is relatively high. Therefore, in this embodiment, a method is proposed to produce deionized water without powering the EDI device (no power supply) until the salt content of the ion exchanger increases, and then powering on and operating the EDI device once the salt content has increased to a certain extent. Furthermore, the inventors of this invention discovered that by producing deionized water by only introducing treated water into the desalination chamber without powering on the concentration chamber and electrode chamber of the EDI device, the same quality of deionized water can be obtained compared to continuously operating the EDI device while powering it on, and power consumption and wastewater volume can be reduced. Moreover, there is no reason why water cannot be introduced into the concentration chamber and electrode chamber of the EDI device without power; water can be introduced into these chambers even without power. Furthermore, the term "no power supply" as used here refers to a state in which the water dissociation reaction has not occurred within the EDI device. It also includes situations where a weak voltage is applied between the electrodes beforehand to prevent ions from diffusing from the concentration chamber to the desalination chamber. For example, this includes situations where a voltage of less than 0.83V is applied to each desalination chamber because the theoretical voltage required for water dissociation is 0.83V.

[0019] FIG1 is a block diagram showing one configuration example of the deionized water manufacturing system of the present invention. FIG2 is a schematic diagram showing a schematic configuration example of the electro-deionized water manufacturing apparatus shown in FIG1. ​​FIG3 and 4 are schematic diagrams showing another schematic configuration example of the electro-deionized water manufacturing apparatus shown in FIG1. ​​FIG2 to FIG4 are configurations disclosed in the aforementioned Patent Document 1.

[0020] As shown in Figure 1, the deionized water manufacturing system of the present invention includes an electrical deionization water manufacturing apparatus (EDI device) 1 for manufacturing deionized water from treated water, a power supply device 2 for applying the necessary DC voltage to the EDI device 1 to maintain the deionization performance, and a control device 3 for controlling the operation of the entire deionized water manufacturing system. The treated water is fed into the desalination chamber (D) of the EDI device 1 via a pump (not shown), and treated water (deionized water) is manufactured through the desalination chamber (D). The water quality is determined by measuring the conductivity of the treated water and the treated water using known conductivity meters 4 (41 and 42). Furthermore, the discharge volume (manufacturing volume) of the treated water from the desalination chamber (D) of the EDI device 1 is measured using a known flow meter (cumulative flow meter) 5. The control device 3 is connected to the conductivity meters 4 and the flow meter 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 manufacturing volume of the treated water, to the control device 3. Furthermore, valve 6 is used to control the supply and stop of treated water to the concentration chamber (C) and electrode chamber (E) of the EDI device 1. The concentrated water discharged from the concentration chamber (C) and the electrode water discharged from the electrode chamber are respectively discharged into the drain tank 7.

[0021] The control device 3 is connected to the power supply 2, pump, and valve 6 via a known communication means, and can control the operation of the power supply 2 and the pump and valve 6. The control device 3 controls the on / off state of the power supply 2, and simultaneously uses the pump and valve 6 to control the supply and stop of treated water to the desalination chamber (D) of the EDI device 1, and the supply and stop of treated water to the concentration chamber (C) and electrode chamber (E) of the EDI device 1. Furthermore, the control device 3 is equipped with a timer to control the operating time of the EDI device 1 in the two operating modes described later (water intake mode and water intake and regeneration mode). The communication means between the control device 3 and the power supply 2, pump, and valve 6, and between the control device 3 and the conductivity meter 4 and flow meter 5, can use any known wired or wireless communication means, and the communication standard can also use any known standard.

[0022] The control device 3 can be implemented, for example, using a well-known PLC (Programmable Logic Controller). The control device 3 can also be implemented using a well-known information processing device (computer) equipped with a CPU (Central Processing Unit), storage device, I / O interface, communication device, etc. The control device 3 implements the operation method of the deionized water production system of the present invention by executing a program pre-saved in the storage device using the processor of the PLC or information processing device.

[0023] Although not shown in Figure 1, in order to obtain deionized water with sufficiently reduced impurity concentration, the deionized water manufacturing system of the present invention may also include a known reverse osmosis membrane device equipped with a reverse osmosis membrane (RO membrane) upstream of the EDI device 1. The deionized water manufacturing system may also be configured to have multiple reverse osmosis membrane devices connected in series (e.g., two stages). When a two-stage reverse osmosis membrane device is provided, the raw water stored in the storage tank or the like is passed through the first stage reverse osmosis membrane device, the permeate is passed through the second stage reverse osmosis membrane device, and the permeate from the second stage reverse osmosis membrane device is fed into the desalination chamber of the EDI device 1 as the treated water. The reverse osmosis membrane device only needs to be configured with a general reverse osmosis membrane, such as that used in the production of pure water.

[0024] As shown in Figure 2, the EDI device 1 is composed of multiple sets of cation exchange membranes and anion exchange membranes (two sets are shown in Figure 2) arranged between two electrodes (anode 11 and cathode 12), forming electrode chambers 21 and 25, concentration chambers 22 and 24, and a desalination chamber 23. Electrode chamber 21 (anode chamber) is formed by anode 11 and cation exchange membrane 31, and electrode chamber 25 (cathode chamber) is formed by cathode 12 and anion exchange membrane 34. Desalination chamber 23 is formed by anion exchange membrane 32 and cation exchange membrane 33, with two concentration chambers 22 and 24 separated by desalination chamber 23. Concentration chamber 22 on the anode 11 side is formed by cation exchange membrane 31 and anion exchange membrane 32, and concentration chamber 24 on the cathode 12 side is formed by cation exchange membrane 33 and anion exchange membrane 34. The desalination chamber 23 is filled with an ion exchanger (MB) obtained by mixing cation exchanger and anion exchanger. In addition, ion exchangers may be appropriately filled into electrode chambers 21 and 25, as well as concentration chambers 22 and 24.

[0025] The EDI device 1 also has a configuration as shown in Figure 3, in which multiple basic structures (unit groups) consisting of concentration chambers 22, desalination chambers 23 and concentration chambers 24 shown in Figure 2 are arranged side by side between the anode 11 and the cathode 12. In this case, adjacent unit groups can share adjacent concentration chambers. Figure 3 shows a configuration example in which N (N is an integer greater than or equal to 1) unit groups are arranged between the anode 11 and the cathode 12. In the EDI device 1 shown in Figure 3, 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 an ion exchanger (MB) obtained by mixing cation exchangers and anion exchangers. Furthermore, the EDI device 1 shown in Figure 3 is configured 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.

[0026] The EDI apparatus 1 also has a configuration as shown in FIG. 4, in which an intermediate ion exchange membrane 36 is disposed between two concentration chambers 22 and 24 to form two desalination chambers 26 and 27. In the EDI apparatus 1 shown in FIG. 4, anion exchanger (AER) is filled in desalination chamber 26 and cation exchanger (CER) is filled in desalination chamber 27. The water to be treated is passed to desalination chamber 27 and then to desalination chamber 26. The amount of ion exchanger filled in the two desalination chambers 26 and 27 does not need to be the same. For example, it is also possible to fill one desalination chamber with both cation exchanger and anion exchanger and fill the other chamber with only cation exchanger. Alternatively, it is also possible to fill one desalination chamber with both cation exchanger and anion exchanger and fill the other chamber with only anion exchanger.

[0027] Furthermore, the EDI device 1 also has a configuration that removes the ion exchanger (anion exchange membrane 34 or cation exchange membrane 31) that separates the electrode chamber and the concentration chamber, thus forming a chamber that can be used for both the concentration chamber and the electrode chamber.

[0028] Under such configuration, in this embodiment, the operating modes of the EDI device 1 are as follows: a water intake mode in which the water to be treated is passed to the desalination chamber (D) to obtain treated water without powering on the EDI device 1; and a water intake and regeneration mode in which the water to be treated is passed to the desalination chamber (D) while powering on the EDI device 1 to obtain treated water, and at the same time the supply water is passed to the concentration chamber (C) and the electrode chamber (E) to regenerate the ion exchanger.

[0029] For example, if one wishes to obtain treated water with the water quality A1 required for testing used water and discharged water as specified in Japanese Industrial Standard (JIS K 0557), or the water quality of the standard specification Type IV for reagent water as specified in ASTM standards (5 μS / cm (0.5 mS / m)), it is ideal to set the operating time of the water intake mode to within the range of 1.5 to 6.4 times that of the water intake and regeneration mode. Furthermore, if one wishes to obtain 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 ideal to set the operating time of the water intake mode to within the range of 1.5 to 4.0 times that of the water intake and regeneration mode. The lower limit of 1.5 times is determined based on the power consumption reduction rate described later.

[0030] The operating times of the water intake mode and the water intake / regeneration mode can also be determined as follows. For example, regarding treated water, if it is desired to obtain water quality of the aforementioned standard specification (5 μS / cm (0.5 mS / m)), the operating times of the water intake mode and the water intake / regeneration mode should be set in a range of 10% to 31% based on the load rate calculated below. Alternatively, if it is desired to obtain treated water with a better water quality (1 μS / cm (0.1 mS / m)) as specified in the aforementioned Japanese Industrial Standard (JIS K 0557), the operating times of the water intake mode and the water intake / regeneration mode should be set in a range of 10% to 20% based on the load rate calculated below.

[0031] Load rate (%) = (Daily load inflow ÷ Daily regenerant production due to power supply) × 100 Here, let the daily load inflow be Q[meq], the processing flow rate of each desalination chamber be P[L / h], the daily water operation time (the sum of the time when powered on and when not powered on) be T1[h], the conductivity of the treated water be C[μS / cm], the daily regenerant production due to power supply be G[meq], the total power supply time per day be T2[h], the current be I[A], and the Faraday constant be F[C / eq] = 96485. Then, Q[meq] = {(C-0.55)÷126.46}×P×T1 and G[meq] = I×3600×T2÷F×1000 are used for calculation.

[0032] The daily load inflow Q is the value obtained by converting the conductivity of the treated water (minus the conductivity of pure water) into milliequivalents (meq) using the limiting molar conductivity of NaCl. The daily amount of regenerant produced due to energization G is the value obtained by converting the current value during energization into electrical quantity and then converting that quantity into milliequivalents using the Faraday constant.

[0033] Furthermore, the water supplied to the EDI unit 1 should preferably be water with a low concentration of components that may precipitate out if they remain in the concentration chamber during operation in water intake mode. Ideally, the water should have a concentration of ionic silica of 150 μg / L or less, and a hardness (calcium and magnesium concentration) of 100 μg CaCO3 / L or less.

[0034] However, for example, Japanese Patent Application Publication No. 2017-56384 (Patent Document 2) also describes intermittent operation of the EDI device 1. 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 content in the treated water will increase, and proposes an operating method to maintain the boron removal rate. Therefore, Patent Document 2 does not aim to suppress the deterioration of the treated water quality and reduce power consumption and wastewater volume as in this invention, and its operating method is completely different from the deionized water production system of this invention. [Example]

[0035] Hereinafter, embodiments of the present invention will be described. In this embodiment, it is shown that the EDI device 1 is operated by controlling the operation time of the above-mentioned water intake mode and water intake and regeneration mode in the deionized water production system shown in FIG1, thereby suppressing the deterioration of the water quality of the treated water and reducing the power consumption and drainage of the EDI device 1. (First Embodiment) In the first embodiment, a salt-form (chloride ion-form) ion exchange resin is prepared as an anion exchanger and filled together with a regenerable cation exchange resin in the desalination chamber of the EDI device 1. Then, when pure water is introduced into the desalination chamber, concentration chamber and electrode chamber respectively and the ion exchanger is regenerated, the proportion of the current used for the discharge of chloride ions (regeneration of ion exchange resin) is calculated relative to the power supplied to the EDI device 1 and based on the concentration of chloride ions discharged in the form of concentrated water, i.e., the current efficiency, and is graphed. In addition, the change in the water quality of the treated water is also displayed in the graph based on the measurement results of conductivity.

[0036] Figure 5 is a graph showing the changes in current efficiency and conductivity of treated water relative to the regeneration time of the ion exchanger. The fewer ions contained, the lower the conductivity value, so a lower value can be considered to represent better water quality.

[0037] As shown in Figure 5, it is known that the current efficiency is above 90% for about 2 hours after the EDI device 1 is powered on, but it gradually decreases and reaches below 50% after 10 hours. Moreover, when the EDI device 1 is powered on, it can be confirmed that the conductivity of the above-mentioned water quality of the treated water below 1 μS / cm can be achieved in about 1 hour after the power is turned on.

[0038] Therefore, it is known that the current efficiency of EDI device 1 is higher when operating with a higher proportion of salt in the ion exchanger. Furthermore, it is known that if the operating time of EDI device 1 in one cycle, i.e., the water intake and regeneration mode, is set to 2 hours or more, better water quality (lower conductivity) can be achieved. However, as mentioned above, the current efficiency drops below 50% after 10 hours; therefore, the operating time of EDI device 1 in water intake and regeneration mode should preferably be 10 hours or less. (Second Embodiment) In the second embodiment, EDI device 1 was operated under conditions 1 to 5 shown in Table 1 below, and changes in power consumption and treated water quality were compared. Data from continuous operation of EDI device 1 is also shown in Table 1 as a comparative example (Table 1 shows "Comparison").

[0039] [Table 1]

[0040] In the second embodiment, an EDI device (EDI-HF2-1000) 1 manufactured by Orlucan Corporation was used. The flow rate of treated water to the desalination chamber (D) was set to 2000 L / h, and the flow rate of water supplied to the concentration chamber (C) and the electrode chamber (E) was set to 240 L / h during operation in the water intake and regeneration mode. Furthermore, during operation in the water intake and regeneration mode, the EDI device 1 was set to constant current operation with a DC current of 2.5 A. For the desalination chamber (D) of the EDI device 1, permeate water with a permeation rate of 2.5 ± 0.2 μS / cm was supplied through two series-connected reverse osmosis membranes. Table 1 shows the daily operating data after operation for more than two days under the conditions 1 to 5 described above, and after the data had stabilized.

[0041] Figure 6 is a graph showing the changes in the quality of the treated water over one day under conditions 1 to 5 and the comparative example shown in Table 1. Figure 7 is a graph showing the changes in power consumption over one day under conditions 1 to 5 and the comparative example shown in Table 1.

[0042] As shown in Figure 6, it can be confirmed that the conductivity of the treated water decreases when operating in the water intake and regeneration mode, and increases when operating in the water intake mode. Furthermore, it was found that under condition 1, which operates for only 5 hours per day, the conductivity increases significantly (water quality deteriorates significantly). On the other hand, under conditions 3 to 5, the water quality shows a certain degree of stability. However, as shown in Table 1, compared with the comparison group that operates continuously in the water intake and regeneration mode for 24 hours, it can be confirmed that condition 5 consumes more power than the comparison example.

[0043] Conditions 2 through 4 require a total of 7 hours of power-on time per day. However, as shown in Figure 6, the water quality (conductivity) varies. Condition 3 represents the best water quality (lowest conductivity) and is stable. Therefore, the power-on time (operation time of the water intake and regeneration mode) should be set to at least 2 hours per cycle. Condition 5 also requires at least 2 hours of power-on time (operation time of the water intake and regeneration mode) and the water quality (conductivity) is also relatively good, but as mentioned above, power consumption increases. Regarding conditions 3 and 5, the number of times the water intake and regeneration mode is operated per day differs: 3 times for condition 3 and 6 times for condition 5. That is, even if the water quality is the same, increasing the number of times the water intake and regeneration mode is operated will increase the drainage volume and power consumption.

[0044] Table 2 shows the ratio of power-on time to power-off time (no power-on time / power-on time) of EDI device 1 under conditions 1 to 5 and the comparative example shown in Table 1. Table 3 shows the above-mentioned load rate under conditions 1 to 5 and the comparative example shown in Table 1. Power-on time is the operating time in water intake and regeneration mode, and no power-on time is the operating time in water intake mode.

[0045] [Table 2] condition Power-on time: Power-off 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

[0046] [Table 3] condition Load rate [%] 1 19.9 2 14.2 3 14.2 4 14.2 5 7.6 Compare 4.1

[0047] Figure 8 is a graph showing the relationship between the conductivity of the treated water (maximum value in 1 day) and the ratio of the on-time to off-time of EDI device 1 shown in Table 2 (no-power-on time / power-on time). Figure 9 is a graph showing the relationship between the power consumption reduction rate shown in Table 1 and the ratio of the on-time to off-time of EDI device 1 shown in Table 2 (no-power-on time / power-on time).

[0048] Furthermore, Figures 8 and 9, and Figures 10 to 13 described below, show the results after the maximum value calculated under the conditions shown in Tables 1 to 3 has been extended using an approximate curve.

[0049] As shown in Figure 8, if it is desired to obtain treated water with a conductivity of, for example, 1 μS / cm as described above, the ratio of the energizing time to the de-energizing time of the EDI device 1 (no energizing time / energizing time) should be set to 4.0 times or less. Furthermore, as shown in Figure 9, if it is desired to reduce the power consumption of the EDI device 1 by 0% or less, that is, to reduce power consumption further than in the comparative example described above, the ratio of the energizing time to the de-energizing time of the EDI device 1 (no energizing time / energizing time) should be set to 1.5 times or more.

[0050] Figure 10 is a graph showing the relationship between the conductivity of the treated water and the load rate shown in Table 3. Figure 11 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 is a graph showing the relationship between the conductivity of the treated water and the ratio of the energization time to the de-energization time (no energization time / energization time) of EDI device 1 shown in Table 2. Figure 13 is a graph showing the relationship between the conductivity of the treated water and the load rate shown in Table 3. Figure 12 is a further extension and display of the approximate curve starting from the maximum value of the graph shown in Figure 8, and Figure 13 is a further extension and display of the approximate curve starting from the maximum value of the graph shown in Figure 10.

[0051] As shown in Figure 10, if it is desired to obtain treated water with a conductivity of, for example, 1 μS / cm as described above, the load rate should be 20% or less. Furthermore, as shown in Figure 11, if it is desired to reduce the power consumption of EDI device 1 by 0% or less, that is, to reduce power consumption further than the comparative example described above, the load rate should be 10% or more.

[0052] As shown in Figure 12, if it is desired to obtain treated water with a conductivity of, for example, the aforementioned 5 μS / cm, the ratio of the energizing time to the de-energizing time of the EDI device 1 (no energizing time / energizing time) should be set to 6.4 times or less. Furthermore, as shown in Figure 13, if it is desired to obtain treated water with a conductivity of, for example, the aforementioned 5 μS / cm, the load rate should be set to 31% or less.

[0053] That is, when it is desired to obtain treated water with a conductivity of 5 μS / cm as described above, the operating time (no-energization time) of the water intake mode should be set to 1.5 to 6.4 times the operating time (energization time) of the water intake and regeneration mode. Furthermore, when it is desired to obtain treated water with a conductivity of 1 μS / cm as described above, the operating time (no-energization time) of the water intake mode should be set to a range of 1.5 to 3.8 times the operating time (energization time) of the water intake and regeneration mode, and more preferably to a range of 1.5 to 2.4 times.

[0054] Alternatively, when it is desired to obtain treated water with a conductivity of 5 μS / cm, the water intake mode (no power supply) and the water intake and regeneration mode (power supply) should be set in a manner with a load rate in the range of 10% to 31%. Furthermore, when it is desired to obtain treated water with a conductivity of 1 μS / cm, the water intake mode (no power supply) and the water intake and regeneration mode (power supply) should be set in a manner with a load rate in the range of 10% to 20%.

[0055] As explained above, if, according to the present invention, a water intake mode is set where the treated water is passed to the desalination chamber (D) to obtain treated water while the EDI device 1 is not powered on, and a water intake and regeneration mode is set where the treated water 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, and the operating time (no power-on time) of the water intake mode is set to be within the range of 1.5 to 6.4 times the operating time (power-on time) of the water intake and regeneration mode, or the water intake mode (no power-on) and the water intake and regeneration mode (power-on) are set in such a way that the above-mentioned load rate is within the range of 10 to 31%, then the deterioration of the treated water quality can be suppressed and the power consumption and drainage of the EDI device 1 can be reduced.

[0056] At this time, if it is desired to obtain treated water with better water quality (conductivity of 1 μS / cm as mentioned above), the water intake mode (no power-on time) can be set to a range of 1.5 to 4.0 times that of the water intake and regeneration mode (power-on time), or the water intake mode (no power-on) and water intake and regeneration mode (power-on) can be set in such a way that the load rate is in the range of 10 to 20%. [Simplified Explanation of the Diagram]

[0017] [Figure 1] is a block diagram showing one configuration example of the deionized water manufacturing system of the present invention. [Figure 2] is a schematic diagram showing a schematic configuration example of the electro-electric deionized water manufacturing apparatus shown in Figure 1. [Figure 3] is a schematic diagram showing another schematic configuration example of the electro-electric deionized water manufacturing apparatus shown in Figure 1. [Figure 4] is a schematic diagram showing another schematic configuration example of the electro-electric deionized water manufacturing apparatus shown in Figure 1. [Figure 5] is a graph showing the change in current efficiency and conductivity of treated water relative to the regeneration time of the ion exchanger. [Figure 6] is a graph showing the change in water quality of treated water over one day under conditions 1 to 5 and the comparative example shown in Table 1. [Figure 7] is a graph showing the change in power consumption over one day under conditions 1 to 5 and the comparative example shown in Table 1. [Figure 8] is a graph showing the relationship between the conductivity of treated water and the ratio of the energization time to the de-energization time of the EDI device shown in Table 2. [Figure 9] is a graph showing the relationship between the power consumption reduction rate shown in Table 1 and the ratio of the power-on time to the power-off time of the EDI device shown in Table 2. [Figure 10] is a graph showing the relationship between the conductivity of the treated water and the load rate shown in Table 3. [Figure 11] 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] is a graph showing the relationship between the conductivity of the treated water and the ratio of the power-on time to the power-off time of the EDI device shown in Table 2. [Figure 13] is a graph showing the relationship between the conductivity of the treated water and the load rate shown in Table 3.

Claims

1. A method of operating a deionized water manufacturing system, comprising using an electric deionized water manufacturing device to manufacture deionized water from treated water, comprising: The water intake mode involves supplying treated water to the desalination chamber of the electro-deionized water generator when the generator is not powered on. The water intake and regeneration mode alternates with the water intake mode, supplying treated water to the desalination chamber while the generator is powered on to obtain treated water, and simultaneously supplying water to at least one of the concentration chamber and electrode chamber of the electro-deionized water generator. The electro-deionized water generator is operated such that the operating time of the water intake mode is 1.5 to 6.4 times that of the operating time of the water intake and regeneration mode.

2. A method of operating a deionized water manufacturing system, comprising using an electric deionized water manufacturing device to manufacture deionized water from treated water, comprising: The water intake mode involves supplying treated water to the desalination chamber of the electro-deionized water generator when it is not powered on, thereby obtaining treated water. The water intake and regeneration mode alternates with the water intake mode, where the electro-deionized water generator is powered on while the treated water is supplied to the desalination chamber to obtain the treated water, and water is simultaneously supplied to at least one of the concentration chamber and electrode chamber of the electro-deionized water generator. The electro-deionized water generator is operated in both the water intake mode and the water intake and regeneration mode with a load rate in the range of 10% to 31%, which is calculated as follows. 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 (with and without power) be T1[h], the conductivity of the treated water be C[μS / cm], the amount of regenerant generated by power in one day be G[meq], the total power operation time per day be T2[h], the current be I[A], the Faraday constant be F[C / eq]=96485, and Q[meq]={(C-0.55)÷126.46}×P×T1 G[meq]=I×3600×T2÷F×1000, then the load rate (%)=(Q÷G)×100%.

3. The operation method of the deionized water production system as described in claim 1 or 2, wherein, The water intake and regeneration mode operates for more than 2 hours per cycle.

4. The method of operating the deionized water production system as described in claim 1 or 2 is to pass the permeate water that has passed through the reverse osmosis membrane device into the desalination chamber as the water to be treated.

5. The operation method of the deionized water production system as described in claim 1 or 2, wherein, The concentration of ionic silica in the water to be treated is below 150 μg / L, and the hardness is below 100 μg CaCO3 / L, with the hardness being the concentration of calcium and magnesium.

6. A deionized water manufacturing system comprising: an electric deionized water manufacturing apparatus for manufacturing deionized water from treated water; a power supply device for applying a required DC voltage to the electric deionized water manufacturing apparatus; and a control device for setting a water intake mode and a water intake / regeneration mode that alternates with the water intake mode; the water intake mode wherein, when the electric deionized water manufacturing apparatus is not energized, the treated water is passed to the desalination chamber of the electric deionized water manufacturing apparatus to obtain treated water; the water intake / regeneration mode wherein, while the electric deionized water manufacturing apparatus is energized, the treated water is passed to the desalination chamber to obtain the treated water, and water is simultaneously passed to at least one of a concentration chamber and an electrode chamber of the electric deionized water manufacturing apparatus; and the control device operates the electric deionized water manufacturing apparatus such that the operating time of the water intake mode is 1.5 to 6.4 times the operating time of the water intake / regeneration mode.

7. A deionized water manufacturing system comprising: an electric deionized water manufacturing apparatus for manufacturing deionized water from treated water; a power supply device for applying a required DC voltage to the electric deionized water manufacturing apparatus; and a control device for setting a water intake mode and a water intake / regeneration mode that alternates with the water intake mode; the water intake mode wherein, when the electric deionized water manufacturing apparatus is not energized, the treated water is passed to the desalination chamber of the electric deionized water manufacturing apparatus to obtain treated water; the water intake / regeneration mode wherein, while the electric deionized water manufacturing apparatus is energized, the treated water is passed to the desalination chamber to obtain the treated water, and water is simultaneously passed to at least one of the concentration chamber and the electrode chamber of the electric deionized water manufacturing apparatus; and the control device operates the electric deionized water manufacturing apparatus in the water intake mode and the water intake / regeneration mode at a load rate in the range of 10% to 31%, the load rate being calculated as follows. 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 (with and without power) be T1[h], the conductivity of the treated water be C[μS / cm], the amount of regenerant generated by power in one day be G[meq], the total power operation time per day be T2[h], the current be I[A], the Faraday constant be F[C / eq]=96485, and Q[meq]={(C-0.55)÷126.46}×P×T1 G[meq]=I×3600×T2÷F×1000, then the load rate (%)=(Q÷G)×100%.

8. As in request item 6 or 7, a deionized water production system, wherein, The water intake and regeneration mode operates for more than 2 hours per cycle.

9. The deionized water production system of claim 6 or 7 further comprises: a reverse osmosis membrane device that passes the permeate through the reverse osmosis membrane as the treated water to the desalination chamber.

10. The deionized water production system as described in claim 6 or 7, wherein, The concentration of ionic silica in the water to be treated is below 150 μg / L, and the hardness is below 100 μg CaCO3 / L, with the hardness being the concentration of calcium and magnesium.

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