Ultrapure water production device and its operation method

Abstract

To provide an ultrapure water production system that can effectively utilize concentrated water from an RO membrane device or EDI. [Solution] The ultrapure water production apparatus 1 includes a primary pure water system 1a that produces primary pure water and produces ultrapure water from the primary pure water. The primary pure water system 1a includes at least one of a reverse osmosis membrane device 6 and an electrical deionization device 8, and a pipe 20 that supplies facility water containing at least a portion of the concentrated water discharged from at least one of the devices to a facility outside the ultrapure water production apparatus 1.

Description

[Technical field]

[0001] The present invention relates to an ultrapure water production system and an operating method thereof. [Background technology]

[0002] An ultrapure water production system generally comprises a primary pure water system that produces primary pure water, and a subsystem (secondary pure water system) that further treats the primary pure water to produce ultrapure water. The primary pure water system comprises a reverse osmosis (RO) membrane device, an electrical deionization device (EDI), an ultraviolet oxidation device, an ion exchange resin filling device, a membrane degassing device, etc., depending on the quality of the raw water and the required quality of the primary pure water. For example, an RO-EDI system, in which water to be treated is supplied to an RO membrane device and the permeate from the RO membrane device is treated with an EDI, is widely known as a primary pure water system.

[0003] Patent Document 1 describes a water treatment device in which water to be treated is purified by passing it through a softener, a first RO membrane device, and a second RO membrane device in that order. An alkali is added to the water supplied to the first RO membrane device, and an acid is added to the water supplied to the second RO membrane device. This allows high-quality treated water to be obtained from the second RO membrane device. Patent Document 2 describes a technique for returning concentrated water from EDI, which has been used to produce pure water, to the water to be treated. Patent Document 3 describes a pure water production system that has a deionization section that removes ions from RO treated water and a membrane degassing section that degasses dissolved gas in the RO treated water, and uses concentrated water from the deionization section as seal water for a water seal vacuum pump attached to the membrane degassing section. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2002-192152 A [Patent Document 2] Japanese Patent Application Publication No. 11-244854 [Patent Document 3] JP 2004-160380 A Summary of the Invention [Problem to be solved by the invention]

[0005] Factories that manufacture semiconductors and electronic components require high-purity cleaning water to clean the semiconductors and electronic components. In addition, such factories also require water for cleaning the manufacturing equipment within the factory, as make-up water, and scrubber water. In the above-mentioned ultrapure water production system, the produced ultrapure water can be used as the high purity cleaning water. However, the concentrated water from the RO membrane device or EDI is simply discarded or reprocessed within the ultrapure water production system, and the concentrated water has not been effectively used for equipment outside the ultrapure water production system.

[0006] An object of the present invention is to solve the above problems and to provide an ultrapure water production system that can effectively utilize concentrated water from an RO membrane device or EDI, and an operating method thereof. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, according to one aspect of the present invention, there is provided an ultrapure water producing apparatus comprising a primary pure water system for producing primary pure water and for producing ultrapure water from the primary pure water, the primary pure water system comprising at least one of a reverse osmosis membrane device and an electrical regenerative deionization device, and piping for supplying facility water containing at least a portion of the concentrated water discharged from the at least one of the devices to a facility external to the ultrapure water producing apparatus.

[0008] According to another aspect of the present invention, there is provided a method for operating an ultrapure water producing apparatus having a primary pure water system for producing primary pure water and producing ultrapure water from the primary pure water, the primary pure water system having at least one of a reverse osmosis membrane device and an electrical regenerative deionization device, the method including the steps of: supplying facility water containing at least a portion of concentrated water discharged from at least one of the devices to equipment external to the ultrapure water producing apparatus; and operating the primary pure water system so that the pH of the facility water approaches neutral or the conductivity of the facility water is less than a predetermined value. Effect of the Invention

[0009] According to the present invention, concentrated water from an RO membrane device or EDI can be effectively utilized in equipment external to the ultrapure water production system. [Brief description of the drawings]

[0010] [Figure 1] 1 is a block diagram showing a configuration of an ultrapure water production system according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram showing the configuration of an ultrapure water production apparatus as a comparative example. [Diagram 3] FIG. 4 is a block diagram showing the configuration of an ultrapure water production system according to a second embodiment of the present invention. [Figure 4] FIG. 11 is a block diagram showing the configuration of an ultrapure water production system according to a third embodiment of the present invention. [Diagram 5] FIG. 11 is a block diagram showing the configuration of an ultrapure water production system according to a fourth embodiment of the present invention. [Figure 6] FIG. 11 is a block diagram showing the configuration of an ultrapure water production system according to a fifth embodiment of the present invention. [Figure 7] FIG. 13 is a block diagram showing the configuration of an ultrapure water production system according to a sixth embodiment of the present invention. [Figure 8] FIG. 13 is a block diagram showing the configuration of an ultrapure water production system according to a seventh embodiment of the present invention. [Figure 9] FIG. 13 is a block diagram showing the configuration of an ultrapure water production system according to an eighth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. However, the components described in the embodiment are merely examples and are not intended to limit the scope of the present invention.

[0012] (First embodiment) Fig. 1 is a block diagram showing the configuration of an ultrapure water production system according to a first embodiment of the present invention. Referring to Fig. 1, the ultrapure water production system 1 of this embodiment includes a primary pure water system 1a that produces primary pure water and a subsystem 1b that further processes the primary pure water to produce ultrapure water.

[0013] The primary pure water system 1a has an RO-EDI system including a reverse osmosis (RO) membrane device 6 to which the water to be treated is supplied, and an electrical deionization device (EDI) 8 to which the permeate of the RO membrane device 6 is supplied. Before being supplied to the RO membrane device 6, the water to be treated is pretreated to remove impurities according to the raw water quality and the required water quality as primary pure water. In this embodiment, a raw water tank 2, a pump 3a, a pretreatment device 4, an RO raw water tank 5, and a pump 3b are provided in front of the RO membrane device 6. The pretreatment device 4 includes, but is not limited to, a sand filtration device 40, an intermediate tank 41, a pump 42, an activated carbon device 43, a softening device 44, and a decarbonation device 45. In addition, in the rear of the EDI 8, an ultraviolet oxidizer (UVox) 22, a cartridge polisher (CP) 23, a membrane degassing device (MD) 24, and the like are usually provided, but are not limited to these. Between the EDI 8 and the ultraviolet oxidizer 22, a desalted water tank 21 for storing the treated water (desalted water) of the EDI 8 is provided. Furthermore, an ultraviolet oxidation device, an ion exchange resin filling device, a membrane degassing device, etc. may be provided in front of the EDI 8 or at another location. The intermediate tank 41 to the membrane degassing device 24 constitute a primary pure water system 1a.

[0014] The raw water tank 2 communicates with a sand filtration unit 40 via a pipe, and a pump 3a is provided on the pipe. The sand filtration unit 40 communicates with an intermediate tank 41 via a pipe. The intermediate tank 41 communicates with an activated carbon unit 43 via a pipe, and a pump 42 is provided on the pipe. The activated carbon unit 43 communicates with a softening unit 44 via a pipe. The softening unit 44 communicates with a decarbonation unit 45 via a pipe. The decarbonation unit 45 communicates with the RO raw water tank 5 via a pipe.

[0015] The water to be treated may be, for example, industrial water, well water, city water, surface water, wastewater provided from inside or outside a customer's factory, treated sewage water, desalinated seawater, or the like, and one or more of these waters are stored in the raw water tank 2. The pumps 3a and 42 are operated to pass the water to be treated through the sand filtration device 40, the intermediate tank 41, the activated carbon device 43, the softening device 44, and the decarbonation device 45 at an appropriate time. The sand filtration device 40 uses sand as a filter medium to filter the water to be treated. The activated carbon device 43 uses activated carbon with a porous structure to further filter the treated water from the sand filtration device 40. The softening device 44 uses an ion exchange resin that removes hardness components in the water to remove hardness components in the treated water from the activated carbon device 43. The decarbonation device 45 degasses (removes) carbon dioxide gas from the treated water from the softening device 44 using, for example, a decarbonation membrane through which gas can pass. The unit devices that perform the unit operations of pretreatment are not limited to the above devices. For example, a turbidity removing membrane device may be used to remove turbidity from raw water. In addition, an alkali softening device that adds an alkali agent to remove hardness components may be used as a softening device, and a decarbonation tower that removes carbon dioxide components in water by contacting water with an acidic pH with air may be used as a decarbonation device.

[0016] The treated water from the decarbonation device 45 is stored in the RO raw water tank 5 as RO raw water (water to be treated and supplied to the RO membrane device 6). The RO raw water tank 5 is in communication with the RO membrane device 6 via a pipe, and a pump 3b is provided on this pipe. When the pump 3b is operated, the RO raw water (water to be treated) stored in the RO raw water tank 5 is supplied to the RO membrane device 6.

[0017] The RO membrane device 6 has a first RO membrane device 6a and a second RO membrane device 6b. The first RO membrane device 6a includes one or more reverse osmosis membrane elements and is configured to remove impurities from the RO raw water by utilizing reverse osmosis. The first RO membrane device 6a discharges permeated water that has passed through the reverse osmosis membrane and concentrated water that contains impurities separated by the reverse osmosis membrane. The permeated water from the first RO membrane device 6a is supplied to the second RO membrane device 6b. The second RO membrane device 6b has the same structure as the first RO membrane device 6a and discharges permeated water and concentrated water.

[0018] The permeate discharge side of the second RO membrane device 6b is connected to the EDI raw water tank 7 via a pipe. The EDI raw water tank 7 stores the permeate from the second RO membrane device 6b as EDI raw water. The EDI raw water tank 7 is connected to the EDI 8 via a pipe, and a pump 3c is provided on the pipe. By operating the pump 3c, the stored water in the EDI raw water tank 7 (EDI raw water) is supplied to the EDI 8.

[0019] The EDI 8 removes ions from the permeate water supplied from the second RO membrane device 6b via the EDI raw water tank 7 to produce treated water (primary pure water) and discharges concentrated water containing the removed ions. Specifically, the EDI 8 has deionization compartments and concentration compartments arranged alternately, and the deionization compartments and concentration compartments are partitioned by anion exchange membranes and cation exchange membranes arranged alternately. An ion exchange resin is contained in the deionization compartments. Ions in the permeate water are trapped by the ion exchange resin and collected in the concentration compartments by an electric field, where they are discharged as concentrated water.

[0020] Subsystem 1b, which produces ultrapure water from primary pure water, is provided downstream of EDI 8. Subsystem 1b removes traces of ions and TOC (total organic carbon) that could not be completely removed in primary pure water system 1a, and can also remove ions and TOC that have eluted from system components subsequent to primary pure water system 1a.

[0021] In addition to the above-described existing structure, the ultrapure water production apparatus 1 of this embodiment is configured to be capable of supplying facility water to a facility provided outside the ultrapure water production apparatus 1. Specifically, the ultrapure water production apparatus 1 has a cleaning water tank 9 and a pipe 20. The concentrated water discharge side of the EDI 8 is connected to the cleaning water tank 9 via the pipe. The cleaning water tank 9 stores the concentrated water of the EDI 8 as facility water. The pipe 20 supplies the facility water stored in the cleaning water tank 9 to the external facility. The external facility may be, for example, a manufacturing facility such as a semiconductor manufacturing factory or an electronic component manufacturing factory. In this case, the facility water stored in the cleaning water tank 9 can be used as cleaning water, make-up water, or scrubber water for the manufacturing facility.

[0022] As described above, according to the ultrapure water production system 1 of this embodiment, the concentrated water of EDI 8 can be effectively used in external facilities. In regions where water shortages are serious, it is important to increase the recovery rate of water treatment, and from this perspective, it is effective to use the concentrated water as facility water.

[0023] Depending on the quality of facility water (cleaning water, make-up water, scrubber water), corrosion or scale may occur in external facilities, and the yield may decrease due to contamination in the product. In the ultrapure water production apparatus 1 of this embodiment, the primary pure water system 1a is operated so that the pH of the facility water, which is concentrated water of EDI8, approaches neutral, or the conductivity of the facility water is less than a predetermined value. Here, the predetermined value can be set appropriately according to the water quality required by the external facility. This makes it possible to provide facility water having the water quality required by the external facility.

[0024] In order to realize the operation of the primary pure water system 1a, the ultrapure water production apparatus 1 of this embodiment has a pH adjustment device 11 that adjusts the pH of the feed water in the RO membrane device 6 so that the pH of the facility water approaches neutral or the conductivity of the facility water is less than a predetermined value. In the pH adjustment operation of the pH adjustment device 11, a pH meter 10a and a conductivity meter 10b are used. The pH meter 10a measures the pH value of the facility water, which is concentrated water of EDI8. The measurement value of the pH meter 10a is supplied to the pH adjustment device 11. The conductivity meter 10b measures the conductivity of the facility water, which is concentrated water of EDI8. The measurement value of the conductivity meter 10b is supplied to the pH adjustment device 11. The pH adjustment device 11 adjusts the pH of the feed water to the first RO membrane device 6a or the second RO membrane device 6b based on the measurement value of at least one of the pH meter 10a and the conductivity meter 10b so that the pH of the facility water approaches neutral or the conductivity of the facility water is less than a predetermined value. This pH adjustment makes it possible to provide water for use in external facilities, such as manufacturing facilities, having the water quality required by those facilities.

[0025] A specific structure of the pH adjustment will be described below. In this embodiment, the pH adjustment device 11 has an alkali addition device 11a and an acid addition device 11b. The alkali addition device 11a adds an alkali agent to the supply water to the first RO membrane device 6a. The alkali agent is, for example, calcium hydroxide, sodium hydroxide, etc. The acid addition device 11b adds an acid agent to the supply water to the second RO membrane device 6b. The acid agent is, for example, sulfuric acid, hydrochloric acid, etc. The pH adjustment device 11 adjusts the amount of acid agent added by the acid addition device 11b based on the measured value of at least one of the pH meter 10a and the conductivity meter 10b. For example, when the supply water to the first RO membrane device 6a is pH>10, the amount of acid agent added is adjusted so that the supply water to the second RO membrane device 6b is pH≦8.5. This allows the pH of the concentrated water (facility water) of EDI8 to approach neutrality, and the conductivity to be less than a predetermined value. Furthermore, according to the series of operations using the RO membrane described above, it is possible to reduce the concentrations of components such as sodium, carbonate, and hydroxide ions contained in the permeate (EDI raw water) of the second RO device 6b. The reduction in the concentrations of components such as sodium, carbonate, and hydroxide ions contained in the EDI raw water contributes to improving the desalination performance and silica and boron removal performance of the EDI 8, and as a result of this operation, the quality of the treated water of the EDI 8 can be improved. The concentrations of sodium and carbonate in the second RO membrane device 6b are not particularly limited, but it is preferable that, for example, sodium is 1 ppm or less and carbonate is 1 ppm or less.

[0026] The raw water of customers stored in the raw water tank 2 varies, and the pH of the water supplied to the second RO membrane device 6b varies depending on the quality of the raw water stored in the raw water tank 2. In consideration of such variations in the quality of the raw water, it is preferable to adjust the pH of the water supplied to the second RO membrane device 6b to 6 or more and 8.5 or less. In this case, the pH of the concentrated water (water for facility use) can be adjusted to within the range of 5.5 to 8.5. In addition, the conductivity of the concentrated water (water for facility use) can be adjusted to within the range of 1 to 40 μS / cm, more preferably within the range of 1 to 20 μS / cm.

[0027] The effect of the above-mentioned pH adjustment will be described in detail below with reference to comparative examples. Fig. 2 shows the configuration of an ultrapure water production system 100 as a comparative example. This ultrapure water production system 100 has the same configuration as the ultrapure water production system 1 shown in Fig. 1 except for the cleaning water tank 9, the piping 20, the pH adjustment device 11, the pH meter 10a, and the conductivity meter 10b.

[0028] In the comparative ultrapure water production system 100, from the viewpoint of increasing the boron and silica rejection rate and improving the recovery efficiency, an alkaline agent is added to the water supplied to the first RO membrane device 6a (pH>10), and the first RO membrane device 6a and the second RO membrane device 6b are each operated under alkaline conditions. In this case, the permeated water (alkaline) of the first RO membrane device 6a passes through the second RO membrane device 6b, and the permeated water of the second RO membrane device 6b becomes alkaline as sodium is eluted. As a result, the concentrated water of EDI8 becomes alkaline, and its conductivity becomes, for example, 50 to 100 μS / cm. If concentrated water from EDI8, which is alkaline and has a conductivity of 50 to 100 μS / cm, is used as equipment water (cleaning water, make-up water, or scrubber water) for the manufacturing equipment mentioned above, corrosion and scale may occur, and the product may become contaminated, resulting in a decrease in yield.

[0029] In contrast, in the ultrapure water production system 1 of this embodiment, the pH adjustment device 11 adjusts the water supplied to the second RO membrane device 6b so that the pH is ≦8 (or 6≦pH≦8). This makes it possible to bring the pH of the concentrated water of EDI8 closer to neutral, and to make the conductivity, for example, less than 50 μS / cm. In this way, the concentrated water of EDI8 can be made to have the water quality required for use in the production facility, thereby making it possible to suppress corrosion, scale generation, and yield reduction.

[0030] The following modifications can be applied to the ultrapure water production system 1 of this embodiment. The pH adjusting device 11 adjusts the amount of the acid agent added while keeping the amount of the alkaline agent fixed, but is not limited to this. The pH adjusting device 11 may adjust the amount of the alkaline agent added while keeping the acid agent fixed, as long as it can make the pH of the facility water neutral and the conductivity less than a predetermined value. In this case, the pH adjusting device 11 adjusts the amount of the alkaline agent added by the alkali adding device 11a based on the measured value of at least one of the pH meter 10a and the conductivity meter 10b.

[0031] In addition, the cleaning water tank 9 may be filled with an inert gas such as N2, which can suppress the dissolution of gas into the facility water. Furthermore, the EDI 8 may be a two-stage EDI in which a first EDI and a second EDI are connected in series. In this case, only the concentrated water from the first EDI (first stage) may be supplied to the cleaning water tank 9, or the concentrated water from the first EDI (first stage) and the concentrated water from the second EDI (second stage) may be joined together and supplied to the cleaning water tank 9.

[0032] Furthermore, the pH meter 10a may measure the pH of the water supplied to the EDI 8, and the pH adjusting device 11 may adjust the amount of alkaline or acidic agent added based on the measurement value of the pH meter 10a so that the pH of the water supplied to the EDI 8 is 6 or more and 8.5 or less. By adjusting the pH of the water supplied to the EDI 8 to 6 or more and 8.5 or less, the pH of the concentrated water of the EDI 8 can be made neutral, and the conductivity can be made less than a predetermined value (e.g., 50 μS / cm).

[0033] In this embodiment, the pH adjusting device 11 constantly monitors (or monitors at predetermined intervals) the measured values ​​of the pH meter 10a and the conductivity meter 10b while automatically adjusting the amount of the acid or alkali agent added, but this is not limited to this. For example, the measured values ​​of the pH meter 10a and the conductivity meter 10b may be checked manually from time to time to adjust the amount of the acid or alkali agent added so that the pH of the facility water approaches neutral or the conductivity of the facility water is less than a predetermined value.

[0034] In addition, although an acid agent is added to the water supplied to the second RO membrane device 6b, it is also possible to add an acid agent to the water supplied to the EDI 8 from the viewpoint of making the concentrated water of the EDI 8 closer to neutral. However, in this case, the following problems arise. When hydrochloric acid is added as an acid agent to the supply water to the second RO membrane device 6b, chloride ions are rejected by the RO membrane. On the other hand, when hydrochloric acid is added to the supply water to the EDI 8, chloride ions are removed by the EDI 8, and concentrated water containing the removed chloride ions is discharged from the EDI 8. As a result, the conductivity of the concentrated water (facility water) of the EDI 8 increases.

[0035] The concentrated water of EDI 8 may contain hydrogen generated by electrolysis. For this reason, it is preferable to separate the hydrogen contained in the concentrated water of EDI 8 using a gas-liquid separation means. This gas-liquid separation means can be provided, for example, in the upstream of the cleaning water tank 9. In addition to the concentrated water of the EDI 8, clear water may be added to the facility water tank 9. The clear water is, for example, RO treated water, EDI treated water, primary pure water, ultrapure water, or the like. The amount of concentrated water from EDI8 is small compared to the amount of permeate from EDI8. If the amount of concentrated water from EDI8 is insufficient for the amount of water required for the external equipment, a portion of the permeate from EDI8 (EDI treated water) may be added to the concentrated water from EDI8 and used as water for the equipment. In addition, other water may be mixed with the EDI8 concentrated water (facility water).

[0036] The ultrapure water producing system 1 of this embodiment is expected to provide the following effects. In the primary pure water system 1a, when concentrated water (RO concentrated water, EDI concentrated water) is returned to a tank or other equipment located in the upstream stage, certain components are concentrated within the system. For example, EDI concentrated water contains large amounts of components such as carbon dioxide and boron that could not be completely removed by the RO membrane. When these impurity components are returned to the upstream tank, the concentration of the impurity components in the raw water increases accordingly, resulting in so-called cyclic concentration. This cyclic concentration can deteriorate the quality of the pure water and ultrapure water, and increase treatment costs. According to the ultrapure water production system 1 of this embodiment, for example, when a part of the concentrated water of EDI8 is configured to be returned to the equipment upstream of EDI8, the high concentration of boron contained in the concentrated water of EDI8 can be discharged outside the primary pure water system 1a as equipment water, thereby preventing excessive circulating concentration in the primary pure water system 1a. Therefore, the increase in equipment costs due to concentrated circulation can be minimized, and the concentrated water of EDI8 can be effectively used in equipment outside the ultrapure water production system 1. Note that boron does not affect the electrical conductivity or the quality of the equipment water.

[0037] Second embodiment Fig. 3 is a block diagram showing the configuration of an ultrapure water production system according to a second embodiment of the present invention. The ultrapure water production system 1A shown in Fig. 3 has the same configuration as the ultrapure water production system 1 shown in Fig. 1, but differs from the ultrapure water production system 1 in that concentrated water from the second RO membrane device 6b is supplied to a cleaning water tank 9. To avoid duplication, a description of the same configuration as the ultrapure water production system 1 will be omitted.

[0038] The pH meter 10a measures the pH of the facility water stored in the cleaning water tank 9. The conductivity meter 10b measures the conductivity of the facility water stored in the cleaning water tank 9. The pH adjustment device 11 adjusts the pH of the water supplied to the first RO membrane device 6a or the second RO membrane device 6b based on the measured value of at least one of the pH meter 10a and the conductivity meter 10b so that the pH of the facility water approaches neutral or the conductivity of the facility water is less than a predetermined value. For example, the pH adjustment device 11 adjusts the amount of acid agent added by the acid addition device 11b based on the measured value of the conductivity meter 10b so that the conductivity of the facility water is in the range of 1 to 40 μS / cm, preferably 1 to 20 μS / cm. This makes it possible to provide facility water having the water quality required by external equipment (e.g., manufacturing equipment). In this embodiment, both the pH meter 10a and the conductivity meter 10b are attached to the cleaning water tank 9, but this is not limited thereto. The pH meter 10a and the conductivity meter 10b may be attached to a pipe that supplies the concentrated water of the second RO membrane device 6b to the cleaning water tank 9 and a pipe that supplies the concentrated water of EDI8 to the cleaning water tank 9, respectively. For example, since the flow rates of the concentrated water of the second RO membrane device 6b and the concentrated water of EDI8 are known in advance, the pH value of the cleaning water can be calculated from the measurement value and flow rate of the pH meter 10a of each pipe. Similarly, the conductivity of the cleaning water can be calculated from the measurement value and flow rate of the conductivity meter 10b of each pipe. In this case, the pH adjustment device 11 adjusts the pH based on at least one of the calculated values ​​of the pH and the conductivity of the cleaning water.

[0039] The ultrapure water production apparatus 1A of this embodiment also provides the effects described in the first embodiment. In addition to the concentrated water of the EDI 8, the concentrated water of the second RO membrane device can be used as facility water, so that the amount of facility water can be increased. The ultrapure water producing apparatus 1A of this embodiment can also apply the modifications described in the first embodiment to each component. For example, in the primary pure water system 1a, a part of the concentrated water (RO concentrated water, EDI concentrated water) may be returned to equipment such as a water tank arranged in the upstream stage. In this case, as in the first embodiment, the high concentration of boron contained in the concentrated water can be discharged outside the primary pure water system 1a as equipment water, thereby preventing excessive circulating concentration in the primary pure water system 1a. Therefore, the increase in equipment costs due to the concentrated water circulation can be minimized, and the concentrated water from the RO membrane device 6b and the EDI 8 can be effectively used in equipment outside the ultrapure water production system 1.

[0040] (Third embodiment) Fig. 4 is a block diagram showing the configuration of an ultrapure water production system according to a third embodiment of the present invention. The ultrapure water production system 1B shown in Fig. 4 has the same configuration as the ultrapure water production system 1, except that the EDI raw water tank 7, pump 3c, and EDI 8 are deleted from the configuration of the ultrapure water production system 1 shown in Fig. 1, and the cartridge polisher 23 is replaced with an ion exchange resin filling device (SBP) 25. To avoid duplication, a description of the same configuration as the ultrapure water production system 1 will be omitted.

[0041] The concentrated water of the second RO membrane device 6b is supplied to the washing water tank 9 as facility water. The pH meter 10a measures the pH of the concentrated water of the second RO membrane device 6b. The conductivity meter 10b measures the conductivity of the concentrated water of the second RO membrane device 6b. The pH adjustment device 11 adjusts the pH of the supply water of the first RO membrane device 6a or the second RO membrane device 6b based on the measured value of at least one of the pH meter 10a and the conductivity meter 10b so that the pH of the facility water approaches neutral or the conductivity of the facility water is less than a predetermined value. For example, the pH adjustment device 11 adjusts the amount of acid agent added by the acid addition device 11b based on the measured value of the conductivity meter 10b so that the conductivity of the facility water is in the range of 20 to 100 μS / cm, preferably in the range of 10 to 40 μS / cm, and more preferably in the range of 5 to 20 μS / cm. This makes it possible to provide facility water having the water quality required by external facilities (e.g., manufacturing facilities).

[0042] The ultrapure water producing apparatus 1B of this embodiment can also apply the modifications described in the first embodiment to each component.

[0043] (Fourth embodiment) Fig. 5 is a block diagram showing the configuration of an ultrapure water production system according to a fourth embodiment of the present invention. The ultrapure water production system 1C shown in Fig. 5 has the same configuration as the ultrapure water production system 1, except that the softener 44, the decarbonator 45, the pump 3c, the RO membrane device 6 (6a, 6b), the EDI raw water tank 7, and the EDI 8 are removed from the configuration of the ultrapure water production system 1 shown in Fig. 1, a two-bed, three-tower (2B3T) device 46, and an RO membrane device 60 are added, and the cartridge polisher 23 is changed to an ion exchange resin filling device (SBP) 25. To avoid duplication of explanation, explanations of the same configuration as the ultrapure water production system 1 will be omitted.

[0044] The activated carbon device 43 communicates with the 2B3T device 46 via a pipe. The 2B3T device 46 communicates with the RO raw water tank 5 via a pipe. The 2B3T device 46 has a cation exchange resin device, a decarbonation device, and an anion exchange resin device. The cation exchange resin device removes cationic components from the treated water of the activated carbon device 43. The decarbonation device removes carbonate components from the treated water of the cation exchange resin device (treated water from which cation components have been removed). The anion exchange resin device removes anion components from the treated water of the decarbonation device (treated water from which carbonate components have been removed). The cation exchange resin device, decarbonation device, and anion exchange resin device can be those used in existing pure water production systems.

[0045] The treated water from the anion exchange resin device (treated water from which anion components have been removed) is supplied to the RO membrane device 60 via the RO raw water tank 5. The RO membrane device 60 has a configuration similar to that of the first RO membrane device 6a, and removes impurities from the RO raw water by utilizing reverse osmosis. The RO membrane device 60 discharges permeated water that has permeated the reverse osmosis membrane, and concentrated water containing impurities separated by the reverse osmosis membrane. The permeated water from the RO membrane device 60 is supplied to downstream equipment via the desalted water tank 21. The concentrated water from the RO membrane device 60 is supplied to the washing water tank 9 as equipment water.

[0046] In the ultrapure water producing apparatus 1C of this embodiment, the conductivity of the treated water from the 2B3T device 46 can be set to, for example, 0.06 to 5 μS / cm. This allows the conductivity of the concentrated water from the RO membrane device 60 to be reduced, so that it is possible to make the resistivity of facility water, for example, 1 MΩ·cm or more. This makes it possible to provide facility water of the quality required by external facilities (for example, manufacturing facilities).

[0047] In the ultrapure water production system 1C of this embodiment, a desalination facility may be provided, and the concentrated water (facility water) from the RO membrane device 60 may be mixed with other water. Moreover, the modifications described in the first embodiment can be applied to each component of the ultrapure water producing apparatus 1C as well.

[0048] Fifth embodiment Fig. 6 is a block diagram showing the configuration of an ultrapure water production system according to a fifth embodiment of the present invention. The ultrapure water production system 1D shown in Fig. 6 has the same configuration as the ultrapure water production system 1, except that the acid addition device 11b is deleted from the configuration of the ultrapure water production system 1 shown in Fig. 1 and a recovery rate adjustment device 12 is added. To avoid duplication, a description of the same configuration as the ultrapure water production system 1 will be omitted.

[0049] EDI8 can adjust the recovery rate, which indicates the ratio of treated water to feed water. The mechanism for adjusting the recovery rate will be briefly explained. In EDI8, the relationship is [feed water = concentrated water + electrode water + treated water]. Since the amount of electrode water is very small, the recovery rate can be adjusted by controlling the amount of concentrated water and the amount of treated water. Specifically, a first valve for controlling the flow rate is provided in the pipe for discharging the concentrated water, and a second valve for controlling the flow rate is provided in the pipe for discharging the treated water. The recovery rate can be changed by controlling the first and second valves to change the balance of the flow rates of the concentrated water and the treated water. For example, increasing the flow rate of the concentrated water and decreasing the flow rate of the treated water will decrease the recovery rate. Conversely, decreasing the flow rate of the concentrated water and increasing the flow rate of the treated water will increase the recovery rate.

[0050] The measured values ​​of the pH meter 10a and the conductivity meter 10b are supplied to a recovery rate adjustment device 12. Based on the measured value of at least one of the pH meter 10a and the conductivity meter 10b, the recovery rate adjustment device 12 controls the first and second valves to adjust the recovery rate of EDI 8. Specifically, the recovery rate adjustment device 12 adjusts the recovery rate of EDI 8 so that the pH of the facility water approaches neutral or the conductivity of the facility water becomes less than a predetermined value.

[0051] The recovery rate is preferably adjusted in the range of 80 to 95%. The higher the recovery rate, the higher the conductivity of the concentrated water and the further away from neutral the pH of the concentrated water. By lowering the recovery rate, the quality of the concentrated water of EDI8 is improved. For example, the recovery rate adjustment device 12 adjusts the recovery rate of EDI8 based on the measured value of the conductivity meter 10b so that the conductivity of the facility water is in the range of 1 to 40 μS / cm, preferably 1 to 20 μS / cm. This makes it possible to provide facility water having the water quality required by external facilities (e.g., manufacturing facilities).

[0052] The ultrapure water producing apparatus 1D of this embodiment can also apply the modifications described in the first embodiment to each component. Furthermore, by combining the recovery rate adjustment of the ultrapure water production system 1D with the pH adjustment of either the ultrapure water production system 1 or 1A, the quality of the water for use in the facility can be further improved.

[0053] Sixth embodiment Fig. 7 is a block diagram showing the configuration of an ultrapure water production system according to a sixth embodiment of the present invention. The ultrapure water production system 1E shown in Fig. 7 has the same configuration as the ultrapure water production system 1, except that the softening device 44 and the decarbonation device 45 are deleted from the configuration of the ultrapure water production system 1 shown in Fig. 1, and the arrangement of the alkali addition device 11a and the acid addition device 11b is changed. To avoid duplication, a description of the same configuration as the ultrapure water production system 1 will be omitted.

[0054] The activated carbon device 43 is connected via a pipe to the RO raw water tank 5. The acid adding device 11b adds an acid agent to the feed water of the first RO membrane device 6a. The alkali adding device 11a adds an alkali agent to the feed water of the second RO membrane device 6b.

[0055] The pH adjusting device 11 adjusts the amount of alkaline agent added by the alkali adding device 11a based on the measured value of at least one of the pH meter 10a and the conductivity meter 10b so that the pH of the facility water approaches neutral or the conductivity of the facility water is less than a predetermined value. For example, when the pH of the feed water to the first RO membrane device 6a is set to pH<5, the pH of the feed water to the second RO membrane device 6b is set to 6 or more and 8.5 or less. In this case, the conductivity of the concentrated water of EDI8 can be set to 1 to 40 μS / cm, preferably 1 to 20 μS / cm. This makes it possible to provide facility water having the water quality required by external equipment (e.g., manufacturing equipment).

[0056] According to the ultrapure water producing apparatus 1E of this embodiment, the softening device 44 and the decarbonation device 45 are not required, so that it is possible to simplify the configuration of the pretreatment device 4. However, in this case, the removal rate of boron carbonate may decrease. The ultrapure water producing apparatus 1E of this embodiment can also apply the modifications described in the first embodiment to each component.

[0057] Seventh embodiment Fig. 8 is a block diagram showing the configuration of an ultrapure water production system according to a seventh embodiment of the present invention. The ultrapure water production system 1F shown in Fig. 8 has the same configuration as the ultrapure water production system 1, except that a water quality meter 13 is added to the configuration of the ultrapure water production system 1 shown in Fig. 1. To avoid duplication, a description of the same configuration as the ultrapure water production system 1 will be omitted.

[0058] The water quality meter 13 measures the water quality of the treated water of EDI8. For example, the water quality meter 13 measures the water quality items required to provide the water quality required by the customer. Here, the water quality meter 13 measures the electrical conductivity, resistivity, Na, silica, boron, TOC, etc. of the treated water of EDI8. The measured value of the water quality meter 13 is supplied to the pH adjustment device 11.

[0059] The pH adjusting device 11 adjusts the amount of acid agent added by the acid adding device 11b based on the measured value of at least one of the pH meter 10a and the conductivity meter 10b and the measured value of the water quality meter 13. Specifically, the pH adjusting device 11 adjusts the amount of acid agent added so that the treated water of EDI8 meets the specified water quality required by the customer and the concentrated water of EDI8 meets the specified water quality for use in the facility. The specified water quality required by the customer is, for example, water quality that satisfies Na<0.5 ppb, silica<0.1 ppb, boron concentration<50 ppt, and resistivity>18 MΩ·cm.

[0060] According to the ultrapure water producing apparatus 1F of this embodiment, it is possible to provide facility water having the quality required for the manufacturing facility while maintaining the water quality of the treated water of the EDI8 at the level required by the customer. The water quality meter 13 may measure the water quality of the permeated water from the second RO membrane device 6b. In this case, the water quality meter 13 measures the electrical conductivity, resistivity, Na, silica, boron, and the like contained in the permeated water from the second RO membrane device 6b.

[0061] The pH adjustment device 11 can adjust the amount of alkaline or acidic agent added so that the water quality of the permeate from the second reverse osmosis membrane device 6b or the treated water from EDI8 meets the required water quality and so that the pH of the water for facility use approaches neutral or the conductivity of the water for facility use is less than a predetermined value. The ultrapure water producing apparatus 1F of this embodiment can also apply the modifications described in the first embodiment to each component.

[0062] Eighth embodiment Fig. 9 is a block diagram showing the configuration of an ultrapure water producing apparatus according to an eighth embodiment of the present invention. The ultrapure water producing apparatus 1G shown in Fig. 9 has the same configuration as the ultrapure water producing apparatus 1, except that an EDI 14 is added to the configuration of the ultrapure water producing apparatus 1 shown in Fig. 1. To avoid duplication, a description of the same configuration as the ultrapure water producing apparatus 1 will be omitted.

[0063] An EDI 14 is provided in a pipe 20 that communicates with the cleaning water tank 9. The EDI 14 has a structure similar to that of the EDI 8, and removes ions from the facility water supplied from the cleaning water tank 9. The treated water from the EDI 14 is used as the facility water. In this case, it is possible to provide facility water with a water quality having a resistivity of 1 MΩ cm, for example.

[0064] According to the ultrapure water producing apparatus 1F of this embodiment, it is possible to provide facility water of higher quality, and it is possible to provide facility water that is more suitable for external facilities (for example, manufacturing facilities). The quality of the water supplied to EDI14 is sufficiently high compared to that of the water supplied to EDI8. Usually, the lower the quality of the water supplied to EDI8, the higher the cost of the EDI. For example, the cost of an EDI that processes 100 μS / cm water is higher than that of an EDI that processes 20 μS / cm water. Therefore, the cost of EDI14 can be kept lower than that of EDI8.

[0065] Also, instead of the EDI 14, a membrane treatment (UF, RO, etc.), other regenerative ion exchange resins, non-regenerative ion exchange resins, a degassing device, a UV oxidation device, etc. can be used. In this case, too, it is possible to provide water suitable for use in an external facility (for example, a manufacturing facility). The ultrapure water producing apparatus 1F of this embodiment can also apply the modifications described in the first embodiment to each component.

[0066] The configurations of the ultrapure water production apparatus according to the first to eighth embodiments described above may be combined as necessary. For example, the quality of the facility water can be further improved by combining pH adjustment and EDI recovery rate adjustment. The quality of the facility water can be improved to a level that satisfies resistivity > 1 MΩ cm by mixing the EDI8 treated water with the cleaning water tank 9. In addition to the EDI8 treated water, clear water such as RO treated water, EDI concentrated water, primary pure water, and ultrapure water may be added to the facility water tank 9. The present invention may also include the following configuration. The primary pure water system 1a has a reverse osmosis membrane device 6 and an EDI 8. The reverse osmosis membrane device 6 has a single-stage structure including a first reverse osmosis membrane device 6a, or a two-stage structure including a first reverse osmosis membrane device 6a and a second reverse osmosis membrane device 6b to which permeated water from the first reverse osmosis membrane device 6a is supplied. In this case, permeated water from the first reverse osmosis membrane device 6a of the single stage structure or permeated water from the second reverse osmosis membrane device 6b of the two stage structure is supplied to the EDI 8. The facility water may include concentrated water from the EDI 8, or concentrated water from the EDI 8 and concentrated water from the first reverse osmosis membrane device 6a of the single stage structure or the second reverse osmosis membrane device 6b of the two stage structure. In the above case, the pH adjustment device 11 may adjust the pH of the supply water to the first single-stage reverse osmosis membrane device 6a or the second two-stage reverse osmosis membrane device 6b so that the water quality of the treated water from the EDI8 or the permeate from the first single-stage reverse osmosis membrane device 6a or the second two-stage reverse osmosis membrane device 6b meets the required water quality and so that the pH of the facility water approaches neutral or the conductivity of the facility water is less than a predetermined value. [Explanation of symbols]

[0067] 1 Ultrapure water production equipment 1a Primary pure water system 6 Reverse osmosis membrane equipment 8. Electrical regenerator deionizer 20 Piping

Claims

1. An ultrapure water producing apparatus comprising a primary pure water system for producing primary pure water, and for producing ultrapure water from the primary pure water, The primary pure water system comprises: At least one of a reverse osmosis membrane device and an electrodeionization device; and a pipe for supplying facility water containing at least a portion of the concentrated water discharged from the at least one of the devices to a facility outside the ultrapure water producing apparatus; the primary pure water system has the reverse osmosis membrane device, the reverse osmosis membrane device includes a first reverse osmosis membrane device and a second reverse osmosis membrane device to which permeated water from the first reverse osmosis membrane device is supplied; the ultrapure water production apparatus has a pH adjustment device that adjusts the pH of water supplied to the first reverse osmosis membrane device or the second reverse osmosis membrane device so that the pH of the facility water approaches neutral or the conductivity of the facility water becomes less than a predetermined value; The pH adjustment device is an ultrapure water producing apparatus that has an alkali adding means for adding an alkaline agent to the water supplied to the first reverse osmosis membrane device and an acid adding means for adding an acid agent to the water supplied to the second reverse osmosis membrane device, or an acid adding means for adding an acid agent to the water supplied to the first reverse osmosis membrane device and an alkali adding means for adding an alkaline agent to the water supplied to the second reverse osmosis membrane device, and adjusts the amount of the alkaline agent or the acid agent added so that the pH of the water supplied to the second reverse osmosis membrane device is 6 or more and 8.5 or less.

2. the primary pure water system includes the electrodeionization apparatus; The permeate of the second reverse osmosis membrane device is supplied to the electrodeionization device; 2. The ultrapure water producing apparatus according to claim 1, wherein the facility water includes concentrated water from the electrodeionization device, or concentrated water from the electrodeionization device and concentrated water from the second reverse osmosis membrane device.

3. 3. The ultrapure water producing apparatus of claim 2, wherein the pH adjustment device adjusts the pH of the water supplied to the second reverse osmosis membrane device so that the water quality of the treated water from the electrical regenerative deionization device or the permeate from the second reverse osmosis membrane device satisfies a required water quality and the pH of the water for use at the facility approaches neutral or the conductivity of the water for use at the facility is less than a predetermined value.

4. An ultrapure water production apparatus comprising a primary pure water system for producing primary pure water, and for producing ultrapure water from the primary pure water, The primary pure water system comprises: At least one of a reverse osmosis membrane device and an electrodeionization device; and a pipe for supplying facility water containing at least a portion of the concentrated water discharged from the at least one of the devices to a facility outside the ultrapure water producing apparatus; the primary pure water system includes the electrodeionization device, and the electrodeionization device is capable of adjusting a recovery rate indicating a ratio of treated water to feed water; An ultrapure water production apparatus having a recovery rate adjustment device that adjusts the recovery rate of the electrodeionization device so that the pH of the water for use in the facility approaches neutral or the conductivity of the water for use in the facility is less than a predetermined value.

5. 1. A method for operating an ultrapure water production apparatus having a primary pure water system for producing primary pure water, the method comprising the steps of: the primary pure water system includes at least one of a reverse osmosis membrane device and an electric deionization device; supplying facility water containing at least a portion of the concentrated water discharged from at least one of the devices to a facility outside the ultrapure water producing apparatus; and operating the primary pure water system so that the pH of the facility water approaches neutral or the conductivity of the facility water is less than a predetermined value; the primary pure water system includes the reverse osmosis membrane device, the reverse osmosis membrane device including a first reverse osmosis membrane device and a second reverse osmosis membrane device to which permeated water from the first reverse osmosis membrane device is supplied; The step of operating the primary pure water system comprises: adding an alkaline agent to the water supplied to the first reverse osmosis membrane device to adjust the pH of the water to 10 or higher; adding an acid to the water supplied to the second reverse osmosis membrane device to adjust the pH of the water to 6 or more and 8.5 or less; A method for operating an ultrapure water production apparatus comprising:

6. A method for operating an ultrapure water production apparatus having a primary pure water system for producing primary pure water, the method comprising the steps of: the primary pure water system includes at least one of a reverse osmosis membrane device and an electric deionization device; supplying facility water containing at least a portion of the concentrated water discharged from at least one of the devices to a facility outside the ultrapure water producing apparatus; and operating the primary pure water system so that the pH of the facility water approaches neutral or the conductivity of the facility water is less than a predetermined value; the primary pure water system includes the electrodeionization device, and the electrodeionization device is capable of adjusting a recovery rate indicating a ratio of treated water to feed water; The step of operating the primary pure water system comprises: A method for operating an ultrapure water production system, comprising a step of adjusting the recovery rate of the electrodeionization device so that the pH of the water for use in the facility approaches neutral or the conductivity of the water for use in the facility is less than a predetermined value.

7. A method for operating an ultrapure water production apparatus having a primary pure water system for producing primary pure water, the method comprising the steps of: the primary pure water system includes at least one of a reverse osmosis membrane device and an electric deionization device; supplying facility water containing at least a portion of the concentrated water discharged from at least one of the devices to a facility outside the ultrapure water producing apparatus; and operating the primary pure water system so that the pH of the facility water approaches neutral or the conductivity of the facility water is less than a predetermined value; the primary pure water system includes the reverse osmosis membrane device, the reverse osmosis membrane device including a first reverse osmosis membrane device and a second reverse osmosis membrane device to which permeated water from the first reverse osmosis membrane device is supplied; The step of operating the primary pure water system comprises: adding an acid to the water supplied to the first reverse osmosis membrane device to adjust the pH of the water to less than 5; adding an alkaline agent to the water supplied to the second reverse osmosis membrane device to adjust the pH of the water to 6 or more and 8.5 or less; A method for operating an ultrapure water production apparatus comprising:

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