KR102818974B1 - Ultrapure water manufacturing system and operating method of ultrapure water manufacturing system - Google Patents

Abstract

The present invention relates to the provision of an ultrapure water manufacturing system capable of shortening the operating time of an ultrapure water manufacturing system having an ultrafiltration membrane device, and an operating method thereof, comprising: a first ultrafiltration membrane module (110) having a first inlet (11a) for introducing water to be treated, a first permeate outlet (11b) and a first concentrated water outlet (11c) and accommodating a first ultrafiltration membrane inside; and a second ultrafiltration membrane module (120) having a second inlet (12a) for introducing water to be treated, a second permeate outlet (12b) for discharging permeate, and a second concentrated water outlet (12c) for discharging concentrated water, and accommodating a second ultrafiltration membrane inside, wherein each module has a common shape and size, and further, each of the inlet, the permeate outlet, and the concentrated water outlet of each module is arranged at a common position within each module, and further, the first ultrafiltration membrane and the second ultrafiltration membrane have a common molecular weight cutoff. and/or relates to an ultrapure water manufacturing system having an effective membrane area.

Description

Ultrapure water manufacturing system and operating method of ultrapure water manufacturing system

The present invention relates to an ultrapure water manufacturing system and an operating method of the ultrapure water manufacturing system.

Conventionally, ultrapure water used in semiconductor manufacturing processes is manufactured using an ultrapure water manufacturing system. An ultrapure water manufacturing system is composed of, for example, a pretreatment unit that removes suspended substances in raw water to obtain pretreated water, a primary pure water manufacturing unit that removes total organic carbon (TOC) components or ionic components in the pretreated water using a reverse osmosis membrane device or an ion exchange device to manufacture primary pure water, and a secondary pure water manufacturing unit that removes trace impurities in the primary pure water to manufacture ultrapure water. In addition to tap water, well water, groundwater, industrial water, etc., used ultrapure water recovered from a use site (point of use: POU) of ultrapure water (hereinafter referred to as “recovered water”) is used.

In the secondary pure water production unit, the primary pure water is highly processed by ultraviolet oxidation devices, ion exchange pure water devices, and ultrafiltration (UF) membrane devices to produce ultrapure water. The ultrafiltration membrane device is located near the last stage of this secondary pure water production unit and removes fine particles generated from ion exchange resins, etc.

However, the demand for high purity in ultrapure water is increasing every year, and for example, the concentration of fine particles with a particle diameter of 50 nm or more is required to be 1 pcs./mL or less. In addition, the required water quality tends to become more stringent, and the reduction of fine particles with a particle diameter of less than 50 nm, for example, about 10 nm, is also required. Therefore, methods for highly removing fine particles with a smaller particle diameter are being proposed (for example, see Patent Documents 1 and 2).

When operating a new ultrapure water manufacturing system or restarting after a break due to regular inspection, a cleaning test run (operation) is performed to remove impurities mixed in or generated within the ultrapure water manufacturing system and to bring the ultrapure water near the point of use to the desired water quality. Recently, there has been a strong demand for shortening the operation time in order to save resources and improve the operation efficiency of the plant. However, the operation time tends to be longer as the removal of fine particles is attempted to be high.

In addition, Patent Document 3 discloses a method in which, when installing a cleaning ultrafiltration membrane (second particle removal membrane device) at the rear end of an ultrafiltration membrane (first particle removal membrane device) used during normal operation, cleaning water is passed through the ultrafiltration membrane during cleaning, and only the water supply side is cleaned without allowing the cleaning water to permeate the first particle removal membrane device, or the cleaning water is not passed through the first particle removal membrane device and is replaced with a particle removal membrane that has been sterilized in advance. However, in this method, since the second particle removal membrane device is not operated for a long period of time during normal operation, there were problems such as bacteria growing in this location or impurities accumulating in the dead space of the piping. Therefore, it was difficult to perform short-term operation even with such a device.

In addition to the fine particles described above, it is also known that coarse particles of a characteristic size and shape are generated in ultrapure water when an ultrafiltration membrane deteriorates or breaks (see, for example, Patent Document 4).

Japanese Patent Publication No. 2016-064342 International Publication No. 2015/050125 International Publication No. 2015/012248 Japanese Patent Publication No. 2016-083646

The present invention has been made to solve the above-mentioned problem, and its purpose is to provide an ultrapure water manufacturing system and an operating method of the ultrapure water manufacturing system capable of shortening the operating time of an ultrapure water manufacturing system having an ultrafiltration membrane device.

The ultrapure water production system of the present invention is an ultrapure water production system having a plurality of ultrafiltration membrane modules connected in series, wherein the plurality of ultrafiltration membrane modules have a first inlet for introducing water to be treated into the inside, a first permeate outlet for discharging permeate, and a first concentrated water outlet for discharging concentrated water, and includes a first ultrafiltration membrane module accommodating a first ultrafiltration membrane therein, and a second ultrafiltration membrane module accommodating a second ultrafiltration membrane therein, and a second ultrafiltration membrane module accommodating a second ultrafiltration membrane therein, and wherein the first ultrafiltration membrane module and the second ultrafiltration membrane module have common shapes and sizes, and each of the first inlet and the second inlet, the first permeate outlet and the second permeate outlet, the first concentrated water outlet and the second concentrated water outlet are arranged at a common position within each module, and further, the first ultrafiltration membrane and the second ultrafiltration membrane The ultrafiltration membranes are characterized by having a common molecular weight cutoff and/or effective membrane area.

In the ultrapure water production system of the present invention, it is preferable that the flow path of the water to be treated be changed by reconnection of a pipe connecting a first flow path that sequentially flows from the first ultrafiltration membrane module to the second ultrafiltration membrane module, and a second flow path that sequentially flows from the second ultrafiltration membrane module to the first ultrafiltration membrane module, or by switching a valve of the pipe.

In the ultrapure water production system of the present invention, it is preferable that the shapes and sizes of the plurality of ultrafiltration membrane modules are all common, and that the plurality of ultrafiltration membrane modules are arranged at positions where the inlet, the permeate outlet, and the concentrated water outlet are all common.

In the ultrapure water manufacturing system of the present invention, a first permeate outlet pipe connected to the first permeate outlet, a first transfer pipe and a first ultrapure water pipe branched and connected from the first permeate outlet pipe, two on-off valves each installed in the first transfer pipe and the first ultrapure water pipe and capable of switching the flow path of permeate from the first permeate outlet pipe to the first transfer pipe and the first ultrapure water pipe, a second permeate outlet pipe connected to the second permeate outlet, a second transfer pipe and a second ultrapure water pipe branched and connected to the second permeate outlet pipe, two on-off valves each installed in the second transfer pipe and the second ultrapure water pipe and capable of switching the flow path of permeate from the second permeate outlet pipe to the second transfer pipe and the second ultrapure water pipe, a first untreated water supply pipe connected to the first inlet, and a second inlet connected to the second inlet. It is preferable that the second treatment water supply pipe be connected, and have two on-off valves installed in the first treatment water supply pipe and the second treatment water supply pipe, and capable of switching the supply path of the treatment water to the first treatment water supply pipe and the second treatment water supply pipe, wherein the first transfer pipe is connected to the second treatment water supply pipe, and the second transfer pipe is connected to the first treatment water supply pipe, and the path of the treatment water can be switched into a first path for flowing from the first ultrafiltration membrane module to the second ultrafiltration membrane module, and a second path for flowing from the second ultrafiltration membrane module to the first ultrafiltration membrane module by a combination of opening and closing of the six on-off valves.

In the ultrapure water production system of the present invention, instead of the two opening/closing valves of the combination capable of switching the flow paths, it is preferable that a single three-way valve capable of switching two flow paths is provided internally, so that the flow paths of the water to be treated can be switched by the three-way valve at the branch point of the branched and connected pipe into a first flow path for flowing the water from the first ultrafiltration membrane module to the second ultrafiltration membrane module, and a second flow path for flowing the water from the second ultrafiltration membrane module to the first ultrafiltration membrane module.

In addition, in the ultrapure water manufacturing system of the present invention, a first permeate outlet pipe connected to the first permeate outlet, a first untreated water supply pipe connected to the first inlet, a second permeate outlet pipe connected to the second permeate outlet, a second untreated water supply pipe connected to the second inlet, a untreated water pipe supplying untreated water to the first untreated water supply pipe or the second untreated water supply pipe, an ultrapure water pipe sending the permeate from the first permeate outlet pipe or the second permeate outlet pipe to a place of use of the ultrapure water, a transfer pipe transferring the permeate of the first ultrafiltration membrane module to the second untreated water supply pipe or the permeate of the second ultrafiltration membrane module to the first untreated water supply pipe, a first flow path conversion unit capable of switching the flow path of the untreated water from the untreated water pipe to the first untreated water supply pipe or the second untreated water supply pipe, and a first flow path conversion unit capable of switching the flow path of the untreated water from the untreated water pipe to the first untreated water supply pipe or the second untreated water supply pipe, and a second flow path conversion unit for converting the flow path of the untreated water from the ultrapure water pipe to the first untreated water supply pipe or the second untreated water supply pipe. It is preferable that the system have a second flow path switching unit capable of switching the flow path of the permeate of the ultrafiltration membrane to be introduced into the first permeate outlet pipe and the second permeate outlet pipe, a third flow path switching unit capable of switching the flow path of the permeate from the transfer pipe to the first untreated water supply pipe and the second untreated water supply pipe, and a fourth flow path switching unit capable of switching the flow path of the permeate introduced into the transfer pipe to the first permeate outlet pipe and the second permeate outlet pipe, and the flow path of the untreated water can be switched by switching of the first to fourth flow path switching units to a first flow path that flows from the first ultrafiltration membrane module to the second ultrafiltration membrane module, and a second flow path that flows from the second ultrafiltration membrane module to the first ultrafiltration membrane module.

In the ultrapure water production system of the present invention, it is preferable that instead of the combination of each of the first and third flow path switching units and the second and fourth flow path switching units, two four-way valves having at least two flow paths inside and capable of switching their connections are provided, and the flow paths of the water to be treated can be switched by the four-way valves into a first flow path for flowing from the first ultrafiltration membrane module to the second ultrafiltration membrane module and a second flow path for flowing from the second ultrafiltration membrane module to the first ultrafiltration membrane module.

The method for operating the ultrapure water production system of the present invention is a method for operating the ultrapure water production system having a plurality of ultrafiltration membrane modules connected in series, wherein the molecular weight cutoff and/or effective membrane area of the ultrafiltration membrane of the ultrafiltration membrane module in the front stage and the ultrafiltration membrane of the ultrafiltration module in the back stage are common,

In the production of ultrapure water, the ultrafiltration membrane module at the rear end among the ultrafiltration membrane modules processes the permeate of the ultrafiltration membrane module at the front end, and when at least one of the plurality of ultrafiltration membrane modules is replaced, the ultrafiltration membrane module at the rear end in the production of ultrapure water is replaced with a new ultrafiltration membrane module, the flow path is switched with the new ultrafiltration membrane module as the front end and the ultrafiltration membrane module that is not replaced as the rear end, and the washing water is passed through the plurality of ultrafiltration membrane modules to operate the ultrapure water production system.

In the operating method of the ultrapure water production system of the present invention, it is preferable that the ultrafiltration membrane module be replaced when the number of fine particles having a diameter of 20 nm or more contained in the permeate of the ultrafiltration membrane module at the latter stage during ultrapure water production becomes 1000 pcs./L or more.

In addition, a new product does not necessarily have to be one that was manufactured immediately, but rather one that has been used for a shorter period of time than before exchange and has shown less deterioration over time.

According to the ultrapure water manufacturing system and ultrapure water manufacturing method of the present invention, the operating time of an ultrapure water manufacturing system having an ultrafiltration membrane device can be shortened.

Figure 1 is a block diagram schematically showing an ultrapure water manufacturing system according to an embodiment.
Figure 2a is a drawing schematically showing one embodiment of the configuration of piping connecting two ultrafiltration membrane devices.
Figure 2b is a drawing schematically showing the structure of the ultrafiltration membrane module shown in Figure 2a.
Figure 3a is a drawing schematically showing another embodiment of the configuration of piping connecting two ultrafiltration membrane devices.
Figure 3b is a drawing schematically showing the structure of the ultrafiltration membrane module shown in Figure 3a.
Figure 4 is a drawing schematically showing the configuration of the piping connecting two ultrafiltration membrane devices and the flow path of the treated water.
Figure 5 is a drawing schematically showing another flow path of the treatment water in the configuration shown in Figure 4.
Fig. 6 is a drawing schematically showing one aspect of the configuration of piping when a three-way valve is used for the configuration shown in Fig. 4.
Fig. 7 is a drawing schematically showing the configuration of the piping and the flow path of the treated water when a euro conversion part is used for the configuration shown in Fig. 4.
Fig. 8 is a drawing schematically showing another flow path of the treatment water in the configuration shown in Fig. 7.
FIG. 9a is a drawing showing one embodiment of a configuration in which a flow change is performed by reconnecting a pipe in the configuration shown in FIG. 7.
Fig. 9b is a drawing showing an example of a configuration in which the pipe is reconnected and the flow path is switched for the configuration of Fig. 9a.
Fig. 10 is a drawing schematically showing one aspect of the configuration of piping when a four-way valve is used for the configuration shown in Fig. 4.
Fig. 11 is a drawing schematically showing one aspect of the configuration of piping when a six-way valve is used for the configuration shown in Fig. 4.
Figure 12 is a schematic diagram showing a configuration in which two or more ultrafiltration membrane units, each consisting of two ultrafiltration membrane devices connected in series, are connected in parallel.
Figure 13 is a schematic diagram showing a configuration in which a single ultrafiltration membrane device has multiple parallel ultrafiltration membrane modules in an ultrafiltration membrane unit comprising two ultrafiltration membrane devices connected in series.
Figure 14 is a schematic diagram showing a configuration in which two or more ultrafiltration membrane units, each consisting of two ultrafiltration membrane devices connected in series, are connected in parallel, and a single ultrafiltration membrane device has a plurality of parallel ultrafiltration membrane modules.
Figure 15 is a graph showing the relationship between the processing time and the number of fine particles in the operational operation of examples and comparative examples.

Hereinafter, the embodiment will be described in detail with reference to the drawings.

In general, in an ultrapure water manufacturing system, when it is put into operation after a new construction or when it is restarted after a shutdown due to equipment replacement or periodic inspection, a cleaning test run (operational run) is performed to remove impurities mixed in or generated within the ultrapure water manufacturing system until the ultrapure water at the point of use reaches the desired water quality. For example, after a shutdown of the device due to equipment replacement or periodic inspection, the ultrapure water manufacturing system is sterilized by passing hydrogen peroxide water through it, and then operation is performed. In this operation run, pure water is continuously passed through the ultrapure water manufacturing system to wash away impurities attached to the water treatment devices or pipes in the ultrapure water manufacturing system. Impurities removed during the operation run include impurities mixed in from the outside during the manufacturing, inspection, or replacement of the ultrapure water manufacturing system, and dust generated from components of the water treatment devices placed in the ultrapure water manufacturing system. In particular, newly manufactured water treatment equipment has more generation than water treatment equipment that has been used for years, and in some cases, it takes a long time for operation after installing a new water treatment equipment through equipment replacement, etc.

The present inventors conducted a thorough examination for the purpose of shortening the above-mentioned operating time, and as a result, found that the fine particles generated during operation have a relatively large particle diameter, exceeding 40 nm and being fine particles of 1 μm or less. For example, Patent Document 4 describes that when the hollow fiber of an ultrafiltration membrane is ruptured, coarse fine particles of 0.4 to 10 μm are generated. It was found that even during operating operation, fine particles are generated by a mechanism similar to the above-mentioned coarse fine particles due to chemical damage by hydrogen peroxide during sterilization or physical damage due to rapid changes in flow rate during membrane exchange or start or stop of water passage, and therefore operation is delayed. In addition, it was found that since the fine particles generated during operation have a larger particle diameter than the fine particles generated during normal pure water production, it is sufficiently possible to remove the coarse fine particles generated during operation even in an ultrafiltration membrane used for ultrapure water production, which has a somewhat lower removal rate.

Therefore, it was found that early operation was possible by installing an ultrafiltration membrane that had been passed through the water during the production of ultrapure water at the rear end of a new filter during operation.

Based on the above knowledge, the ultrapure water production system of the present embodiment is configured to have two or more ultrafiltration membrane devices having ultrafiltration membrane modules of a common structure and specification arranged in series as ultrafiltration membrane devices arranged near the end of the ultrapure water production system.

(First embodiment)

As shown in Fig. 1, the ultrapure water production system (1) according to the first embodiment has a pretreatment unit (14), a primary pure water production unit (15), and a secondary pure water production unit (13). The secondary pure water production unit (13) has two ultrafiltration membrane devices (11, 12) for removing fine particles in water.

The pretreatment unit (14) removes suspended substances in the raw water to produce pretreated water, and supplies the pretreated water to the primary pure water production unit (15). The pretreatment unit (14) is configured by appropriately selecting, for example, a sand filter device, a precision filter device, etc. for removing suspended substances in the raw water, and is also configured by providing a heat exchanger, etc. for controlling the temperature of the raw water, as needed. In addition, depending on the quality of the raw water, the pretreatment unit (14) may be omitted.

Raw water includes, for example, tap water, well water, groundwater, industrial water, and water used in semiconductor manufacturing plants, and then recovered and treated (recovered water).

The primary pure water production unit (15) is configured by appropriately combining one or more of a reverse osmosis membrane device, a degassing device (a decarbonation tower, a vacuum degassing device, a membrane degassing device, etc.), an ion exchange device (a cation exchange device, an anion exchange device, a mixed-bed ion exchange device, etc.), and an ultraviolet oxidation device. The primary pure water production unit (15) removes ionic components, nonionic components, and dissolved gases in the pretreated water to produce primary pure water, and supplies the primary pure water to the secondary pure water production unit (13). The primary pure water has, for example, a total organic carbon (TOC) concentration of 5 μgC/L or less, a resistivity of 17 MΩㆍcm or more, and a particle count of 100,000 pcs./L or less with a particle diameter of 20 nm or more.

The secondary pure water production unit (13) removes trace impurities from the primary pure water to produce ultrapure water. The secondary pure water production unit (13) is configured by appropriately combining one or more of an ultraviolet oxidation device, a membrane degassing device, a non-regenerative mixed-bed ion exchange device, etc., as needed, on the upstream side of an ultrafiltration membrane unit (the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) are collectively referred to as the ultrafiltration membrane unit. The same applies hereinafter).

The ultrafiltration membrane devices (11, 12) each have at least one ultrafiltration membrane module that accommodates an ultrafiltration membrane inside, and are connected in series so that the permeate from the ultrafiltration membrane device in the front stage is supplied to the ultrafiltration membrane device in the back stage.

The first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) remove fine particles having a particle diameter of, for example, 50 nm or more, preferably 20 nm or more, in water. The ultrapure water thus produced is supplied to a point of use (POU) (16). The ultrapure water has, for example, a total organic carbon (TOC) concentration of 1 μgC/L or less, a resistivity of 18 MΩㆍcm or more, and a particle count of 20 nm or more in particle diameter of 1,000 pcs./L or less.

As the ultrafiltration membrane used here, an asymmetric membrane of cellulose triacetate, a composite membrane of aromatic polyamide, a composite membrane of polyvinyl alcohol, etc. are generally used. As the ultrafiltration membrane, a composite membrane of an aromatic polyamide membrane having a composite material of the above polysulfone agent is preferably used. The membrane shape is, but is not limited to, a sheet flat membrane, a spiral membrane, a tubular membrane, a hollow fiber membrane, etc. It is preferable that the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) all have two or more ultrafiltration membranes made of a common material and a common shape, and it is more preferable that the material and shape of the membranes of all the ultrafiltration membranes of the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) are common. When the ultrafiltration membranes of the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) have different materials and shapes, when the ultrafiltration membrane modules are switched, the replacement cycle is likely to be significantly shortened, and the removal performance of fine particles may be reduced, easily causing the water quality to deteriorate.

The specifications of the ultrafiltration membrane module that accommodates such ultrafiltration membranes are, as an example, preferably such that the molecular weight cutoff of the ultrafiltration membrane is 4,000 to 6,000, the effective membrane area is 10 m2 to 35 m2, and the design operating differential pressure is 0.1 MPa to 0.4 MPa. In addition, the particulate removal performance is preferably such that the removal rate of particulates having a particle diameter of 20 nm or more is 65% or more. It is preferable that at least a part of the two or more ultrafiltration membranes of the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) have in common the molecular weight cutoff or the effective membrane area among the above specifications, and it is more preferable that the molecular weight cutoff and the effective membrane area are in common. In addition, in the plurality of ultrafiltration membrane modules, it is preferable that the outer diameter, length, arrangement position of the inlet, arrangement position of the permeate outlet, arrangement position of the concentrated water outlet, the diameter of the corresponding pipe, and the shape of the joint of the corresponding pipe are all in common. In addition, it is more preferable that the above specifications are common to all ultrafiltration membrane modules of the two or more ultrafiltration membrane modules of the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12). If the above specifications are not common to the ultrafiltration membrane modules, when the ultrafiltration membrane modules are switched, the replacement cycle is likely to be significantly shortened, and the removal performance of fine particles may deteriorate, easily causing the water quality to deteriorate.

As commercially available products of this type of ultrafiltration membrane module, (product name: OAT-6036, OLT-6036, OLT-5026, manufacturer: Asahi Kasei) can be used.

Immediately after the secondary pure water production unit (13), a particle meter (18) is placed. The particle meter (18) measures the number of particles in water, preferably having a particle diameter of 50 nm or more, more preferably having a particle diameter of 20 nm or more. As the particle meter (10), for example, the particle meter UltraDI-20 manufactured by Particle Measuring Systems can be used. The particle meter (18) measures the number of particles in the permeate of the ultrafiltration membrane device on the downstream side (rear stage).

In the ultrapure water production system (1) of the present embodiment, when the particle count by the particle meter (18) becomes, for example, 5,000 pcs./L or more of particles having a particle diameter of 50 nm or more, or preferably 1,000 pcs./L or more of particles having a particle diameter of 20 nm or more, the ultrafiltration membrane module in the upstream ultrafiltration membrane device of the ultrafiltration membrane unit is moved and installed to the ultrafiltration membrane module in the downstream ultrafiltration membrane device, so that a new ultrafiltration membrane module is placed in the upstream end. In addition, the upstream end here means a position on the upstream side when water flows through it, and the downstream end means a position on the downstream side.

Here, the ultrapure water manufacturing system (1) shown in Fig. 1 has two ultrafiltration membrane devices, but the ultrapure water manufacturing system (1) may have three or more ultrafiltration membrane devices connected in series. In addition, the ultrapure water manufacturing system (1) may have a configuration in which two or more ultrafiltration membrane device units connected in series are connected in parallel.

Next, the configuration and piping configuration of the ultrafiltration membrane module according to the first embodiment will be described with reference to FIGS. 2A and 2B. FIG. 2A is a drawing schematically showing one aspect of the configuration of piping connecting the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) of the present embodiment. As shown in FIG. 2A, the first ultrafiltration membrane device (11) has a first ultrafiltration membrane module (11), and the second ultrafiltration membrane device (12) has a second ultrafiltration membrane module (120).

Here, Fig. 2a shows an example in which one ultrafiltration membrane device is equipped with one ultrafiltration membrane module, but the present invention is not limited thereto, and one ultrafiltration membrane device may be equipped with two or more ultrafiltration membrane modules.

Fig. 2b is a drawing schematically showing the structure of an ultrafiltration membrane module (11) used in the present embodiment. The ultrafiltration membrane module (11) accommodates an ultrafiltration membrane (11m) in a cylindrical housing (11h) that is hollow inside. Both ends of the housing (11h) are sealed liquid-tightly, and a permeate outlet (11b) is opened in each end. In addition, in the housing (11h), an inlet (11a) for treatment water and an outlet (11c) for concentrated water are respectively installed on the wall surfaces near both ends rather than the longitudinal center of the housing (11h). In the ultrafiltration membrane module (110), the treatment water introduced into the interior of the housing (11h) from the inlet (11a) for treatment water is filtered in the process of flowing from the primary side (feed side) of the ultrafiltration membrane (11m) to the secondary side (permeate side), and permeate is generated. The generated permeate flows out from the permeate outlet (11b). The concentrated water flows through the primary side of the ultrafiltration membrane (11m) and flows out from the concentrated water outlet (11c). The structure of the second ultrafiltration membrane module (120) is also the same, and has a treated water inlet (12a) and a concentrated water outlet (12c) on the side wall of the housing, and permeate water outlets (12b) on both ends. An ultrafiltration membrane is accommodated inside the ultrafiltration membrane module (120).

In addition, Fig. 3a is a drawing schematically showing one aspect other than the configuration of the piping connecting the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) in the present embodiment. As shown in Fig. 3a, the first ultrafiltration membrane device (11) has a first ultrafiltration membrane module (210), and the second ultrafiltration membrane device (12) has a second ultrafiltration membrane module (220).

Here, Fig. 3a shows an example in which one ultrafiltration membrane device is equipped with one ultrafiltration membrane module, but the present invention is not limited thereto and one ultrafiltration membrane device may be equipped with two or more ultrafiltration membrane modules.

Fig. 3b is a drawing schematically showing the structure of another ultrafiltration membrane module (210) used in the present embodiment. The ultrafiltration membrane module (210) shown in Fig. 3b is different from the ultrafiltration membrane module (110) shown in Fig. 2b in the arrangement positions of the inlet for the treated water, the outlet for the permeate water, and the outlet for the concentrated water with respect to the housing, but the other configurations are the same. In the ultrafiltration membrane module (210), the inlet for the treated water (21a) is opened at one end of the housing (21h), and the outlet for the permeate water (21b) is opened at the other end. In addition, the outlet for the concentrated water (21c) is opened on the wall surface of the housing (21h). As a commercially available product of such an ultrafiltration membrane module (210), such as NTU-3306-K6R manufactured by Nitto Denko Co., Ltd. can be used. The second ultrafiltration membrane module (220) is also the same.

Here, when the ultrafiltration membrane modules of the configuration shown in Fig. 3b are connected in series, the permeate outlet (21b) of the ultrafiltration membrane module (210) and the inlet (22a) of the second ultrafiltration membrane module (220) are connected. This connection may be made using a pipe, or the permeate outlet (21b) of the first ultrafiltration membrane module (210) and the inlet (22a) of the second ultrafiltration membrane module (220) may be directly connected. The untreated water is supplied from the inlet (21a) of the first ultrafiltration membrane module into the first ultrafiltration membrane module (210) and is subjected to ultrafiltration treatment here. The concentrated water flows out from the concentrated water outlet (21c), and the permeate water is supplied from the permeate outlet (21b) to the inlet (22a) of the second ultrafiltration membrane module (220). The permeate is introduced into the second ultrafiltration membrane module (220) and is filtered therein. The concentrated water of the second ultrafiltration membrane module (220) flows out from the concentrated water outlet (22c), and the permeate flows out from the permeate outlet (22b). In this way, the permeate of the second ultrafiltration membrane module (220) is obtained as ultrapure water.

In the ultrafiltration membrane unit of the present embodiment, the arrangement of the inlet (11a) of the first ultrafiltration membrane module (110) and the inlet (12a) of the second ultrafiltration membrane module (120), the arrangement of the permeate outlet (11b) of the first ultrafiltration membrane module (110) and the permeate outlet (12b) of the second ultrafiltration membrane module (120), and the arrangement of the concentrated water outlet (11c) of the first ultrafiltration membrane module (110) and the concentrated water outlet (12c) of the second ultrafiltration membrane module (120) as shown in FIGS. 2a and 2b are all common. That is, the arrangement positions of the inlet, the permeate outlet, and the concentrated water outlet in the housings of the first ultrafiltration membrane module (110) and the second ultrafiltration membrane module (120) are each common to each other. Therefore, any ultrafiltration membrane module can be switched and replaced without changing the arrangement or shape of the piping of the ultrapure water manufacturing system connected to the inlet, permeate outlet, and concentrated water outlet of the ultrafiltration membrane module. The same applies to Figs. 3a and 3b.

As shown in Fig. 2a, in the ultrafiltration membrane unit of the present embodiment, a treatment water supply pipe (111) is connected to the first ultrafiltration membrane device (11) for supplying treatment water (for example, primary pure water produced in the primary pure water production section (15). The primary pure water is obtained through one or more of an ultraviolet oxidation device, a membrane degassing device, a non-regenerative mixed-bed ion exchange device, etc., and may be supplied to the first ultrafiltration membrane module (110) (hereinafter the same)). The treatment water supply pipe (111) is connected to an inlet (11a) of the ultrafiltration membrane module (110). An openable valve (V1) is installed in the treatment water supply pipe (111).

In the first ultrafiltration membrane device (11), a concentrated water outlet (114) is connected to the concentrated water outlet (11c) of the ultrafiltration membrane module (110). A permeate outlet pipe (112) is connected to the permeate outlet (11b). A transfer pipe (115) for transferring the permeate to the second ultrafiltration membrane device (12) at the subsequent stage is connected to the permeate outlet pipe (112). A valve (V4) is installed in the transfer pipe (115). The valve (V4) is configured to be openable. The transfer pipe (115) is connected to the inlet (12a) of the second ultrafiltration membrane module (120).

In the second ultrafiltration membrane device (12), a concentrated water outlet pipe (124) is connected to the concentrated water outlet (12c) of the ultrafiltration membrane module (120). A permeate outlet pipe (122) is connected to the permeate outlet (12b). An ultrapure water pipe (123) for transporting the permeate of the second ultrafiltration membrane device (12) to a use point is connected to the permeate outlet pipe (122). A valve (V6) is installed in the ultrapure water pipe (123). The valve (V6) is configured to be openable.

Next, a water treatment method using the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) will be described. First, when producing ultrapure water in the ultrapure water production system (1), raw water is supplied to the pretreatment unit (14) and processed in the order of the pretreatment unit (14) and the primary pure water production unit (15) to produce primary pure water.

This primary pure water is supplied to the secondary pure water manufacturing unit (13). At this time, valve (V1), valve (V4), and valve (V6) are open.

The primary pure water supplied to the secondary pure water production unit (13) is sequentially passed through the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) and processed. Specifically, the primary pure water is supplied from the treatment water supply pipe (111) to the first ultrafiltration membrane module (110) through the inlet (11a), and is filtered there. The permeate of the first ultrafiltration membrane module (110) is supplied from the permeate outlet (11b) to the inlet (12a) of the second ultrafiltration membrane module (120) through the permeate outlet pipe (112) and the transfer pipe (115). The concentrated water of the first ultrafiltration membrane module (11) flows out from the concentrated water outlet pipe (114) through the concentrated water outlet pipe (11c). At this time, the primary purified water may be supplied to the first ultrafiltration membrane module (110) through one or more of an ultraviolet oxidation device, a membrane degassing device, a non-regenerative mixed-bed ion exchange device, etc.

The permeate supplied to the introduction port (12a) of the second ultrafiltration membrane module (120) is introduced into the second ultrafiltration membrane module (120) and subjected to filtration treatment therein. The permeate of the second ultrafiltration membrane module (120) is supplied to the use point from the permeate outlet port (12b) through the permeate outlet pipe (122) and the ultrapure water pipe (123). The concentrated water of the second ultrafiltration membrane module (120) is discharged from the concentrated water outlet pipe (124) through the concentrated water outlet port (12c). In this way, ultrapure water can be manufactured for a predetermined period of time.

If the production of ultrapure water continues, the ultrafiltration membrane deteriorates and the quality of the ultrapure water deteriorates. At this time, the ultrapure water production system (1) is stopped for a moment and the ultrafiltration membrane module is replaced. This ultrafiltration membrane module replacement is performed by placing a new ultrafiltration membrane module at the frontmost stage and a used ultrafiltration membrane module at the rear stage, as described below. At this time, the ultrafiltration membrane module that has been used for a longer period of time is placed at the rear stage.

In the ultrafiltration membrane unit of Fig. 2a, first, the second ultrafiltration membrane module (120) at the rear end is replaced. The second ultrafiltration membrane module (120) is removed, and the first ultrafiltration membrane module (110) is moved and installed therein. Then, a new ultrafiltration membrane module is placed in the first ultrafiltration membrane device (11). When replacing this ultrafiltration membrane module, it is preferable that the valve (V1), the valve (V4), and the valve (V6) are closed in order to prevent the inflow of water from the treatment water supply pipe (111) or the backflow of water from the downstream side and to keep the inside of the pipe clean.

Next, the first ultrafiltration membrane device (11) having a new ultrafiltration membrane module arranged as the first ultrafiltration membrane module (11) is put into operation. During this operation, each valve is in the same state as when the ultrapure water is manufactured, that is, the valve (V1), the valve (V4), and the valve (V6) are open. In this state, primary pure water flows as cleaning water into the ultrafiltration membrane unit, and the operation is carried out. The cleaning water (primary pure water) is sequentially passed through the treatment water supply pipe (111) to the first ultrafiltration membrane device (11) having a new ultrafiltration membrane module arranged, and then to the second ultrafiltration membrane device (12). In addition, in the operational operation, the cleaning water may be passed through the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12), but after passing through the second ultrafiltration membrane device (12), it may be passed through devices arbitrarily installed in the pretreatment unit (14), the first pure water production unit (15), and the second pure water production unit (13).

This operational operation is performed until the number of fine particles in the permeate of the second ultrafiltration membrane device (12) becomes lower than a predetermined value. In the operational operation, a lot of dust is generated from the new ultrafiltration membrane module equipped in the first ultrafiltration membrane device (11), but these are captured by the second ultrafiltration membrane device (12). Therefore, this operational operation can be completed earlier than if the first ultrafiltration membrane device (11) replaced with a new module is operated as a single unit. In this way, the operational operation time can be shortened by arranging the new ultrafiltration membrane module in the front stage and the ultrafiltration membrane module used over time in the rear stage. In addition, the operational operation can be performed without special piping or equipment for performing the operational operation.

After the operational operation is completed, the treated water is supplied to the treated water supply pipe (111) in the same manner as above, and the production of ultrapure water begins.

Next, a method for realizing the exchange and operation of the above ultrafiltration membrane module by opening and closing a valve is described. According to this method, when exchanging a new ultrafiltration membrane module, the exchange and operation can be performed without involving the switching of the ultrafiltration membrane module that is not to be exchanged, so that the workload can be reduced.

In this method, as shown in FIG. 4, in addition to the configuration shown in FIG. 2a, a configuration is used that has a pipe and a valve that can switch which path to flow between the first path through which the treated water flows from the first ultrafiltration membrane module (110) to the second ultrafiltration membrane module (120) and the second path through which the treated water flows from the second ultrafiltration membrane module (120) to the first ultrafiltration membrane module.

As shown in Fig. 4, an ultrapure water pipe (113) is connected to the permeate outlet pipe (112) so as to be connected to a use point and to transport the permeate of the first ultrafiltration membrane device to the use point. A valve (V3) is installed in the ultrapure water pipe (113). The valve (V3) is configured to be openable and closable in the same manner as the valve (V4), and by opening and closing these, the flow path of the permeate of the first ultrafiltration membrane module (110) is switched to the ultrapure water pipe (113) or the transport pipe (115). In addition, the ultrapure water pipe (113) can be disconnected from the use point, thereby allowing the permeate of the ultrafiltration membrane device (11) to be discharged to the outside.

In addition, a treatment water supply pipe (121) capable of supplying treatment water (for example, primary purified water that has passed through at least one of an ultraviolet oxidation device, a membrane degassing device, a non-regenerative mixed-bed ion exchange device, etc.) to a second ultrafiltration membrane device (12) instead of the first ultrafiltration membrane device (11) is connected to the path of the transfer pipe (115). The treatment water is supplied from the treatment water supply pipe (121) to the inlet (12a) through the transfer pipe (115). An openable valve (V2) is installed in the treatment water supply pipe (121).

A transfer pipe (125) capable of transferring the permeate to the first ultrafiltration membrane device (11) of the previous stage is connected to the permeate outlet pipe (122) of the second ultrafiltration membrane module (120). A valve (V5) is installed in the transfer pipe (125). The valve (V5) is configured to be openable and closable, and by opening and closing the valve (V5) and the valve (V6), the flow path of the permeate of the second ultrafiltration membrane device (12) that has passed through the permeate outlet pipe (122) is switched to the ultrapure water pipe (123) or the transfer pipe (125).

The transfer pipe (125) is connected to the downstream side of the valve (V1) of the treatment water supply pipe (111), and the permeate from the second ultrafiltration membrane device (12) can be supplied from the transfer pipe (125) to the inlet (11a) of the first ultrafiltration membrane device (11) through the treatment water supply pipe (111).

First, as shown in Fig. 4, the valve (V1), the valve (V4), and the valve (V6) are open, and the valve (V2), the valve (V3), and the valve (V5) are closed, that is, the first ultrafiltration membrane device (11) is arranged in the front stage and the second ultrafiltration membrane device (12) is arranged in the rear stage, to manufacture ultrapure water. The flow of the treated water at this time is the same as the flow described in Fig. 2a. After a predetermined period of time has passed since the start of manufacture, when the ultrafiltration membrane deteriorates and the water quality of the ultrapure water deteriorates, the ultrapure water manufacturing system (1) is temporarily stopped and the ultrafiltration membrane module is replaced. The ultrafiltration membrane module is first replaced by replacing the second ultrafiltration membrane module (120) in the rear stage. The second ultrafiltration membrane module (120) is removed, and a new ultrafiltration membrane device module is placed therein. In addition, in Fig. 4, the black valve is closed, and the white valve is open. The same is true of Fig. 5. Also, the thick lines in Figs. 4 and 5 indicate the path through which the treated water flows.

Next, the second ultrafiltration membrane device (12) having the new second ultrafiltration membrane module (120) is put into operation. During this operation, as shown in Fig. 5, valves (V1), (V4), and (V6) are closed, and valves (V2), (V3), and (V5) are opened. As a result, the arrangement of the second ultrafiltration membrane device (12) in the front and the first ultrafiltration membrane device (11) in the rear is changed. Then, pure water is passed through the ultrafiltration membrane module as cleaning water, and the operation is carried out. The cleaning water (primary pure water) is passed through the treated water supply pipe (121) to the second ultrafiltration membrane module (120) after exchange, and then to the first ultrafiltration membrane module (110) in that order.

Specifically, the cleaning water is supplied from the treatment water supply pipe (121) through the transfer pipe (115) to the inlet (12a) of the second ultrafiltration membrane module (120). Then, the cleaning water flows through the second ultrafiltration membrane module (120) and is supplied from the permeate outlet (12b) to the inlet (11a) of the first ultrafiltration membrane module (110) through the permeate outlet pipe (122) and the transfer pipe (125).

The cleaning water supplied to the inlet (11a) of the first ultrafiltration membrane module (110) flows through the first ultrafiltration membrane module (110), then flows out from the permeate outlet (11b), and is discharged through the permeate outlet pipe (112) and the ultrapure water pipe (113) in sequence. At this time, the connection between the ultrapure water pipe and the use point is disconnected.

This operational operation is performed until the number of fine particles in the permeate of the first ultrafiltration membrane device (11) that is the subsequent stage becomes lower than a predetermined value. In the operational operation, a lot of dust is generated from the new ultrafiltration membrane module placed in the first ultrafiltration membrane device (12), but these are captured by the first ultrafiltration membrane device (11). Therefore, this operational operation can be completed earlier than when the second ultrafiltration membrane device (12) that has been replaced with a new module is operated as a unit.

After the operation is completed, the treated water is supplied to the treated water supply pipe (111) and the production of ultrapure water begins. At this time, each valve is closed in the same manner as the operation described above: valve (V1), valve (V4), and valve (V6), and valve (V2), valve (V3), and valve (V5) are opened, so that the second ultrafiltration membrane device (12) is arranged in the front stage and the first ultrafiltration membrane device (11) is arranged in the back stage. The primary pure water supplied from the primary pure water production unit (5) flows sequentially to the second ultrafiltration membrane device (12) and then to the first ultrafiltration membrane device (11).

If the production of ultrapure water continues in this state, the first ultrafiltration membrane module (110) that has been used for a long time will deteriorate before the second ultrafiltration membrane module (120) that has been replaced with a new one. At this time, the first ultrafiltration membrane module (110) that is the rear end is replaced. At this time, the first ultrafiltration membrane module (110) is removed and a new ultrafiltration membrane module is placed.

Then, the first ultrafiltration membrane device (11) having a new first ultrafiltration membrane module (110) is put into operation. At this time, as shown in Fig. 4, valves (V1), (V4), and (V6) are opened, and valves (V2), (V3), and (V5) are closed. As a result, the arrangement of the first ultrafiltration membrane device (11) is changed to the front end, and the arrangement of the second ultrafiltration membrane device (12) is changed to the rear end. In this state, primary purified water is passed through the ultrafiltration membrane module as cleaning water, and the operation is carried out. The cleaning water is sequentially passed through the first ultrafiltration membrane device (11) having a new ultrafiltration membrane module placed therein, and then through the second ultrafiltration membrane device (12).

This operational operation is performed until the number of fine particles in the permeate of the second ultrafiltration membrane device (12) becomes lower than a predetermined value. In the operational operation, a lot of dust is generated from the new ultrafiltration membrane module placed in the first ultrafiltration membrane device (11), but these are captured by the second ultrafiltration membrane device (12). Therefore, this operational operation can be completed earlier than when the first ultrafiltration membrane device (11) replaced with a new module is operated as a unit.

After the operation is completed, the treated water is supplied to the treated water supply pipe (111) and the production of ultrapure water begins. At this time, the valves are opened in the same manner as in the above operation, such as valve (V1), valve (V4), and valve (V6), and valve (V2), valve (V3), and valve (V5) are closed, so that the first ultrafiltration membrane device (11) is maintained as the front end and the second ultrafiltration membrane device (12) is maintained as the rear end. As a result, the primary pure water supplied from the primary pure water production unit (5) flows sequentially to the first ultrafiltration membrane device (11) and then to the second ultrafiltration membrane device (12).

By repeating the above operation, the first ultrafiltration membrane module (110) and the second ultrafiltration membrane module (120) are sequentially exchanged and operated, and ultrapure water can be manufactured. At this time, since the operating time after the replacement with a new module is significantly shortened, high-quality ultrapure water can be manufactured efficiently. In addition, the arrangement positions of the inlet, the permeate outlet, and the concentrated water outlet in the housings of the ultrafiltration membrane modules provided in the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) are each arranged in a common arrangement. Therefore, it is possible to exchange them by switching any ultrafiltration membrane module without changing the arrangement or shape of the piping of the ultrapure water manufacturing system connected to the inlet, the permeate outlet, and the concentrated water outlet of the ultrafiltration membrane module.

In addition, the ultrafiltration membrane device placed at the rear end can be configured to perform full filtration only by installing a valve in the concentrated water outlet pipe (114 or 124) and closing this valve. By using this full filtration, the water recovery rate of the ultrafiltration membrane device can be improved. This full filtration can be performed both during operation and after operation has ended, but it can also be performed only after operation has ended. In addition, this full filtration can be performed in the same manner in other embodiments.

Fig. 6 shows the piping configuration of the ultrafiltration membrane unit when a three-way valve is used instead of the above-described on-off valve. In Fig. 6, components having the same functions as those in Figs. 2 to 5 are given the same reference numerals and duplicate descriptions are omitted. As shown in Fig. 6, instead of the combination of the valve (V3) and the valve (V4) in Figs. 4 and 5, and the combination of the valve (V5) and the valve (V6), a three-way valve (V31) and a three-way valve (V32) may be provided, respectively. In this case, the three-way valve (V31) is installed at the branch point of the ultrapure water pipe (113) and the transfer pipe (115), and the three-way valve (V32) is installed at the branch point of the ultrapure water pipe (123) and the transfer pipe (125), and the flow path can be switched in the same manner as above. Specifically, in the above operation, the three-way valve (V31) switches the flow path of the permeate from the permeate outlet pipe (112) to the ultrapure water pipe (113) and the transfer pipe (115). In addition, in the above operation, the three-way valve (V32) switches the flow path of the permeate from the permeate outlet pipe (122) to the ultrapure water pipe (123) and the transfer pipe (125).

When a three-way valve is used instead of an on-off valve, the retention area of water within the ultrapure water production system (1) can be reduced, so that the deterioration of ultrapure water quality is less, and high-purity ultrapure water can be produced over a longer period of time.

(Second embodiment)

Next, another embodiment of the configuration of the piping connecting the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) will be described with reference to FIGS. 7 and 8. In FIGS. 7 and 8, components having the same function as those in FIGS. 2 to 6 are given the same reference numerals and duplicate descriptions are omitted.

The ultrafiltration membrane unit of the second embodiment switches the order of water flow to the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) by reconnecting the piping without using an on-off valve.

The ultrafiltration membrane unit of the present embodiment shown in Fig. 7 has a treatment water pipe (40) for supplying treatment water to the ultrafiltration membrane unit, and a flow path switching section (R1) for switching the flow path of treatment water from the treatment water pipe (40) to a flow path to an inlet (11a) of a first ultrafiltration membrane device (11) and a flow path to an inlet (12a) of a second ultrafiltration membrane device (12). The flow path switching section (R1) is connected to the treatment water pipe (40).

The euro switching section (R1) is configured by a switching mechanism that switches the pipe to the above-described euro. The euro switching sections (R2 to R4) described later are the same. For example, in Fig. 7, the switching mechanism is configured to enable switching by separating the euro switching section (switching mechanism) (R1 to R4) from the pipes to which it is connected, rotating it 180 degrees around the switching center (Rp), and connecting the euro switching section (switching mechanism) (R1 to R4) to each pipe of the ultrafiltration membrane device.

The switching mechanism can be assembled using piping parts such as pipes or joints. Commercially available products thereof include those manufactured by Sekisui Kagaku, for example. By using a union joint or valve joint at the end (connection portion) that connects to the piping of the switching mechanism, it is possible to easily separate it without using special tools, so that switching can be easily performed. The shape of the connection portion is preferably a TS type or a flange type. Screw types and welding types are not preferred because they are not easy to separate. The switching mechanism is preferably made of a material such as polyvinylidene fluoride (PVDF), chlorinated polyvinylidene chloride resin (CPVC), or polytetrafluoroethylene (PTFE), and PVDF is particularly preferred.

In addition, the ultrafiltration membrane unit of the present embodiment is configured to be able to convert the permeate of the ultrafiltration membrane device, which is introduced into the ultrafiltration pipe (30) that transports ultrafiltration water to a use point, into the permeate of the first ultrafiltration membrane device (11) and the permeate of the second ultrafiltration membrane device (12), and has a flow path conversion section (R2) that converts the flow path connected to the ultrafiltration pipe (30) into the flow path of the permeate flowing through the permeate outlet pipe (112) of the first ultrafiltration membrane device (11) and the flow path of the permeate flowing through the permeate outlet pipe (122) of the second ultrafiltration membrane device (12). The flow path conversion section (R2) is connected to the ultrafiltration pipe (30).

In addition, the ultrafiltration membrane unit of the present embodiment is configured to supply the permeate of the first ultrafiltration membrane device (11) to the untreated water supply pipe (121) of the second ultrafiltration membrane device (12) via the transfer pipe (115), or to supply the permeate of the second ultrafiltration membrane device (12) to the first ultrafiltration membrane device (11) via the transfer pipe (115), and has a flow path switching section (R3) that switches the flow path connected to the transfer pipe (115) between the untreated water supply pipe (121) of the second ultrafiltration membrane device (12) and the untreated water supply pipe (111) of the first ultrafiltration membrane device (11). The flow path switching section (R3) is connected to the transfer pipe (115).

In addition, the ultrafiltration membrane unit of the present embodiment is configured to be able to convert the permeate of the ultrafiltration membrane device introduced into the transfer pipe (115) into the permeate of the first ultrafiltration membrane device (11) and the permeate of the second ultrafiltration membrane device (12), and has a flow path conversion section (R4) that converts the flow path connected to the transfer pipe (115) into the flow path of the permeate flowing through the permeate outlet pipe (112) of the first ultrafiltration membrane device (11) and the flow path of the permeate flowing through the permeate outlet pipe (122) of the second ultrafiltration membrane device (12). The flow path conversion section (R4) is connected to the transfer pipe (115).

The transfer pipe (115) serves as both the transfer pipe (115) and the transfer pipe (125) of the first embodiment. In addition, the ultrapure water pipe (30) serves as both the ultrapure water pipe (113) and the ultrapure water pipe (123) of the first embodiment.

Next, a water treatment method in the ultrafiltration membrane unit of the present embodiment will be described. First, when producing ultrapure water in the ultrapure water production system (1), raw water is supplied to the purification unit (14) and sequentially treated in the pretreatment unit (14) and the primary pure water production unit (15) to produce primary pure water. At this time, as shown in Fig. 7, the treated water pipe (40) and the treated water supply pipe (111) are connected by the flow path switching unit (R1). In addition, one end of the permeate outlet pipe (112) and the transfer pipe (115) are connected by the flow path switching unit (R2). In addition, the other end of the transfer pipe (115) and the treated water supply pipe (121) are connected by the flow path switching unit (R3). In addition, the permeate outlet pipe (122) and the ultrapure water pipe (30) are connected by the flow path switching unit (R4). This results in the first ultrafiltration membrane device (11) being arranged in the front, and the second ultrafiltration membrane device (12) being arranged in the back. In the ultrafiltration membrane unit shown in Fig. 7, a flow path flowing from the first ultrafiltration membrane module to the second ultrafiltration membrane module is formed by the treatment water pipe (40), the flow path switching section (R1), the treatment water supply pipe (111), the inlet (11a), the first ultrafiltration membrane module (110), the permeate outlet (11b), the permeate outlet pipe (112), the flow path switching section (R4), the transport pipe (115), the flow path switching section (R3), the treatment water supply pipe (121), the inlet (12a), and the second ultrafiltration membrane module (120).

The primary pure water supplied from the primary pure water production unit to the ultrafiltration membrane unit through the treatment water pipe (40) is sequentially processed in the first ultrafiltration membrane module (110) and the second ultrafiltration membrane module (120). The ultrapure water thus produced is supplied to the use point through the ultrapure water pipe (30). Specifically, the primary pure water is supplied from the treatment water supply pipe (111) to the first ultrafiltration membrane module (110) through the inlet (11a). The permeate flowing through the first ultrafiltration membrane module (110) is supplied to the second ultrafiltration membrane module (120) through the permeate outlet pipe (112), the transfer pipe (115), and the treatment water supply pipe (121) through the inlet (12a). In addition, the ultrapure water generated by flowing through the second ultrafiltration membrane module (120) flows out to the use point through the permeate outlet pipe (122) and the ultrapure water pipe (30).

If the production of ultrapure water continues, the ultrafiltration membrane deteriorates and the ultrapure water quality deteriorates. Therefore, if a particle meter UltraDI-20 manufactured by Particle Measuring Systems, for example, is installed in the ultrapure water pipe (30) to monitor the number of fine particles, the number of fine particles gradually increases. At this time, the ultrapure water production system (1) is temporarily stopped, and the second ultrafiltration membrane module (120) in the subsequent stage is replaced in the same manner as in the above embodiment. A new ultrafiltration membrane module is placed in the second ultrafiltration membrane device (12), and the second ultrafiltration membrane device (12) is operated. Such replacement and operation of the ultrafiltration membrane may be performed periodically.

When the second ultrafiltration membrane device (12) is in operation, the connection of the flow path switching section is switched as shown in Fig. 8. That is, the treated water pipe (40) and the treated water supply pipe (121) are connected by the flow path switching section (R1). In addition, the permeate outlet pipe (112) and the ultrapure water pipe (30) are connected by the flow path switching section (R2). In addition, the transport pipe (115) and the treated water supply pipe (111) are connected by the flow path switching section (R3). In addition, the permeate outlet pipe (122) and the transport pipe (115) are connected by the flow path switching section (R4). As a result, the arrangement of the second ultrafiltration membrane device (12) as the front end and the arrangement of the first ultrafiltration membrane device (11) as the rear end is changed. In the ultrafiltration membrane unit shown in Fig. 8, a flow path for flowing from the second ultrafiltration membrane module (120) to the first ultrafiltration membrane module (110) is formed by the treated water pipe (40), the flow path switching section (R1), the treated water supply pipe (121), the inlet (12a), the second ultrafiltration membrane module (120), the permeate outlet (12b), the permeate outlet pipe (122), the flow path switching section (R4), the transport pipe (115), the flow path switching section (R3), the treated water supply pipe (111), the inlet (11a), and the first ultrafiltration membrane module (110).

In this state, cleaning water is supplied from the treatment water pipe (40) to the ultrafiltration membrane unit. The cleaning water sequentially flows through the new second ultrafiltration membrane module (120) and then the first ultrafiltration membrane module (110). Specifically, the cleaning water is supplied from the treatment water supply pipe (121) to the second ultrafiltration membrane module (120) through the introduction portion (12a). The cleaning water that has flowed through the second ultrafiltration membrane module (120) is supplied to the first ultrafiltration membrane module (110) through the permeate outlet pipe (122), the transfer pipe (115), and the treatment water supply pipe (111) through the introduction port (11a). In addition, the cleaning water flows through the first ultrafiltration membrane module (110) and is discharged through the permeate outlet pipe (112) and the ultrapure water pipe (30). In addition, during operation, the connection between the ultrapure water pipe (30) and the use point is disconnected.

This operational operation is performed until the number of fine particles in the permeate of the first ultrafiltration membrane device (11) becomes below a predetermined value. In the operational operation, although a lot of dust is generated from the new second ultrafiltration membrane module (120), these are captured by the first ultrafiltration membrane device (11). Therefore, this operational operation can be completed earlier than when the new second ultrafiltration membrane module (120) is operated as a unit.

After the operational operation is completed, the connection of the euro switching section is switched as shown in Fig. 8, and the raw water is supplied to the pretreatment section (14) to start the production of ultrapure water. The primary pure water sent from the primary pure water production section (15) passes through the second ultrafiltration membrane module (120) and the first ultrafiltration membrane module (110) in that order as the treated water, and the permeate of the first ultrafiltration membrane module (110) is sent to the use point. As a result, high-purity ultrapure water can be stably supplied to the use point.

If the production of ultrapure water continues, the ultrafiltration membrane deteriorates and the quality of the ultrapure water deteriorates. At this time, the first ultrafiltration membrane module (110) is replaced. A new ultrafiltration membrane module is placed in the first ultrafiltration membrane device (11), and the first ultrafiltration membrane device (11) is put into operation.

When the first ultrafiltration membrane device (11) is in operation, as shown in Fig. 7, the treatment water pipe (40) and the treatment water supply pipe (111) are connected by the flow path switching unit (R1). In addition, one end of the permeate outlet pipe (112) and the transfer pipe (115) are connected by the flow path switching unit (R2). In addition, the other end of the transfer pipe (115) and the treatment water supply pipe (121) are connected by the flow path switching unit (R3). In addition, the permeate outlet pipe (112) and the ultrapure water pipe (30) are connected by the flow path switching unit (R4). As a result, the arrangement is changed so that the first ultrafiltration membrane device (11) is in the front stage and the second ultrafiltration membrane device (12) is in the back stage. In this state, the cleaning water is supplied from the treatment water pipe (40) to the ultrafiltration membrane unit.

The cleaning water supplied to the ultrafiltration membrane device is supplied to the first ultrafiltration membrane module (110) through the inlet (11a) from the untreated water supply pipe (111). The cleaning water flowing through the first ultrafiltration membrane module (110) is supplied to the second ultrafiltration membrane module (12) through the permeate outlet pipe (112), the transfer pipe (115), and the untreated water supply pipe (121) from the inlet (12a). In addition, the cleaning water flowing through the second ultrafiltration membrane module (120) is discharged through the permeate outlet pipe (122) and the ultrapure water pipe (30). In addition, during operation, the connection between the ultrapure water pipe (30) and the use point is disconnected.

This operational operation is performed until the number of fine particles in the permeate of the second ultrafiltration membrane device (12) becomes lower than a predetermined value. In the operational operation, a lot of dust is generated from the new first ultrafiltration membrane module (110), but these are captured by the second ultrafiltration membrane device (12). Therefore, this operational operation can be completed earlier than when the new first ultrafiltration membrane module (110) is operated as a unit.

After the operational operation is completed, the connection of the euro switching section is switched as shown in Fig. 7, and the raw water is supplied to the pretreatment section (14) to start the production of ultrapure water. The primary pure water sent from the primary pure water production section (15) is passed through the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) in the same order as described above, and the permeate of the second ultrafiltration membrane device (12) is sent to the use point. As a result, high-purity ultrapure water can be stably supplied to the use point.

By repeating the above operation, the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) are sequentially exchanged and operated, and ultrapure water can be manufactured. At this time, since the operating time after replacement with a new module is significantly shortened, high-quality ultrapure water can be manufactured efficiently. In addition, the arrangement positions of the inlet, the permeate outlet, and the concentrated water outlet in the housings of the ultrafiltration membrane modules provided in the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) are each common to each other. Therefore, without changing the arrangement or shape of the piping of the ultrapure water manufacturing system connected to the inlet, the permeate outlet, and the concentrated water outlet of the ultrafiltration membrane module, any ultrafiltration membrane module can be moved and replaced.

The above-mentioned euro switching section (R1 to R4) is composed of, for example, two opening/closing valves (Rpv) constituting a switching mechanism (Rp), two bend pipes (L1, L2) connected to each of the opening/closing valves (Rpv) and constituting a euro switching section, and a pipe (L115) that integrates the switching mechanism and the euro switching section, as shown in FIGS. 9a and 9b.

As shown in FIGS. 9a and 9b, the flow path switching unit (R1) shown in FIGS. 7 and 8 is composed of an on-off valve (Rpv) connected to a treatment water pipe (40), and a bend pipe (L1) connected to the on-off valve (Rpv). When configuring the flow path shown in FIG. 7, the end of the bend pipe (L1) on the opposite side of the on-off valve (Rpv) is connected to the inlet (11a) of the first ultrafiltration membrane module (110), and when configuring the flow path shown in FIG. 8, as shown in FIG. 9b, the end of the bend pipe (L1) on the opposite side of the on-off valve (Rpv) is connected to the inlet (12a) of the second ultrafiltration membrane module (120).

As shown in FIGS. 9a and 9b, the flow path switching unit (R2) shown in FIGS. 7 and 8 is composed of an on-off valve (Rpv) connected to an ultrapure water pipe (30), and a bent pipe (L2) connected to the on-off valve (Rpv). When configuring the flow path shown in FIG. 7, as shown in FIG. 9a, the end of the bent pipe (L2) on the opposite side of the on-off valve (Rpv) is connected to the permeate pipe (122) of the second ultrafiltration membrane module (120) via an on-off valve (V122). When configuring the flow path shown in FIG. 8, as shown in FIG. 9b, the end of the bent pipe (L2) on the opposite side of the on-off valve (Rpv) is connected to the end of the permeate outlet pipe (112) of the first ultrafiltration membrane module (110) via an on-off valve (V121).

As shown in FIGS. 9a and 9b, the transfer pipe (115), the flow path switching section (R3), and the flow path switching section (R4) shown in FIGS. 7 and 8 are configured by a pipe (L115) having a bending section as a switching mechanism. When configuring the flow path shown in FIG. 7, as shown in FIG. 9a, one end of the pipe (L115) is connected to the permeate pipe (121) of the first ultrafiltration membrane module (110) via an on-off valve (V121), and the other end is connected to the inlet (12a) of the second ultrafiltration membrane module (120). When configuring the flow path shown in Fig. 8, one end of the pipe (L115) is connected to the inlet (11a) of the first ultrafiltration membrane module (110), as shown in Fig. 9b, and the other end is connected to the permeate pipe (122) of the second ultrafiltration membrane module (120) through an on-off valve (V122).

Reconnection of these pipes (L115) and bends (L1, L2) can be performed by removing the pipes (115) and bends (L1, L2) while closing each of the on-off valves (V121, V122, Rpv), changing the connection point, and reconnecting them.

Fig. 10 shows the piping configuration of the ultrafiltration membrane unit when a 4-way valve is used instead of the above-described flow diverter. In Fig. 10, components having the same functions as those in Figs. 2 to 9 are given the same reference numerals and duplicate descriptions are omitted. As shown in Fig. 10, instead of the combination of the flow diverter (R1) and the flow diverter (R3) in Figs. 7 and 9, and the combination of the flow diverter (R2) and the flow diverter (R4), a 4-way valve (V41) and a 4-way valve (V42) may be used, respectively. The 4-way valve has 4 inlets and 2 channels inside, and can switch the flow of the treated water by changing the combination of the inlets connected by the 2 channels.

A four-way valve (V41) is installed at one end of a treatment water pipe (40), a treatment water supply pipe (111), a transfer pipe (115), and a branch point of a treatment water supply pipe (121), and a four-way valve (V42) is installed at the other end of an ultrapure water pipe (30), a transfer pipe (115), and a branch point of a permeate outlet pipe (112) and a permeate outlet pipe (122), and can switch flow paths in the same manner as described above. Specifically, the four-way valve (V41) switches flow paths from the treatment water pipe (40) to the treatment water supply pipe (111), flow paths from the transfer pipe (115) to the treatment water supply pipe (121), flow paths from the treatment water pipe (40) to the treatment water supply pipe (121), and flow paths from the transfer pipe (115) to the treatment water supply pipe (111). A four-way valve (V42) switches the flow path from the permeate outlet pipe (112) to the ultrapure water pipe (30), and from the permeate outlet pipe (122) to the transfer pipe (115), and from the permeate outlet pipe (112) to the transfer pipe (115), and from the permeate outlet pipe (122) to the ultrapure water pipe (30).

When a four-way valve is used instead of an on-off valve, the retention area of water within the ultrapure water production system (1) can be reduced, so that the deterioration of ultrapure water quality is less, and high-purity ultrapure water can be produced over a longer period of time.

(Third embodiment)

Next, another embodiment of the configuration of the piping connecting the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) will be described with reference to Fig. 11. The secondary pure water production unit (133) of the third embodiment switches the order of water flow to the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) by a six-way valve. The six-way valve has six inlets and three channels inside, and the channels of the treated water can be switched by changing the combination of the inlets connected by the three channels.

In the secondary pure water production unit (133) of the present embodiment, the functions of the transfer pipe (115) and the flow path switching units (R1 to R4) in the ultrafiltration membrane unit of the second embodiment shown in Figs. 7 to 8 are integrated into a six-way valve (V60). In the secondary pure water production unit (133) of the present embodiment, the treated water pipe (40) is connected to the treated water supply pipe (111) by the first flow path (61) in the six-way valve (V60). In addition, the permeate outlet pipe (112) for passing the permeate of the first ultrafiltration membrane device (11) is connected to the treated water supply pipe (121) by the second flow path of the six-way valve (V60). In addition, the permeate outlet pipe (122) that passes the permeate of the second ultrafiltration membrane device (12) is connected to the ultrapure water pipe (30) by the third path (63) of the six-way valve (V60). As a result, the treated water passes through the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) in sequence.

And, when changing the order of the treatment water flow through the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) by exchanging the ultrafiltration membrane module, etc., the six-way valve (V60) is switched to connect the permeate outlet pipe (122) and the treatment water supply pipe (111) through the first flow path (61). In addition, the treatment water pipe (40) and the treatment water supply pipe (121) are connected through the second flow path (62). In addition, the permeate outlet pipe (112) and the ultrapure water pipe (30) are connected through the third flow path (63). As a result, the treatment water flows through the second ultrafiltration membrane device (12) and the first ultrafiltration membrane device (11) in that order.

In each process of manufacturing the above ultra-pure water and operating the ultrafiltration membrane device, the order of the flow of the treated water of the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) can be changed by operating the six-way valve (V60) as described above. As a result, the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) can be sequentially replaced and operated to manufacture ultra-pure water. At this time, since the operating time after replacement with a new module is significantly shortened, high-quality ultra-pure water can be efficiently manufactured. In addition, the arrangement positions of the inlet, the permeate outlet, and the concentrated water outlet in the housing of the ultrafiltration membrane module provided in the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) are each common to each other. Therefore, any ultrafiltration membrane module can be moved and replaced without changing the arrangement or shape of the piping of the ultrapure water manufacturing system connected to the inlet, permeate outlet, and concentrated water outlet of the ultrafiltration membrane module.

(4th embodiment)

Fig. 12 is a schematic diagram showing a configuration in which two or more ultrafiltration membrane units, each of which is composed of two ultrafiltration membrane devices connected in series, are connected in parallel. The secondary pure water production unit (13) shown in Fig. 12 has an ultrafiltration membrane unit (17x) equipped with a first ultrafiltration membrane device (11x) and a second ultrafiltration membrane device (12x), an ultrafiltration membrane unit (17y) equipped with a first ultrafiltration membrane device (11y) and a second ultrafiltration membrane device (12y), and an ultrafiltration membrane unit (17z) equipped with a first ultrafiltration membrane device (11z) and a second ultrafiltration membrane device (12z) in parallel. The ultrafiltration membrane unit (17x), ultrafiltration membrane unit (17y), and ultrafiltration membrane unit (17z) each have a treatment water pipe (171x, 171y, 171z) through which treatment water flows, and an on-off valve (V17x, V17y, V17z) installed in the treatment water supply pipe (171x, 171y, 171z) at the front end of each ultrafiltration membrane unit.

In the configuration shown in Fig. 12, by arranging a new ultrafiltration membrane module in the front end and an ultrafiltration membrane module that has been used for a long time in the rear end in the same unit, the ultrafiltration membrane module can be replaced and the ultrafiltration membrane device can be operated. In addition, by combining the opening and closing of the on-off valves (V17x, V17y, V17z), the ultrafiltration membrane module can be replaced and the ultrafiltration membrane device can be operated in the same manner as in the first to third embodiments in one of the three ultrafiltration membrane units, while the production of ultrapure water can be continued in the other two units. In addition, although Fig. 12 shows a state in which three ultrafiltration membrane units are connected in parallel, the number of ultrafiltration membrane units connected in parallel may be two or four or more, the same. In addition, similarly to the above, the number of ultrafiltration membrane modules that each ultrafiltration membrane device has may be plural as long as it is 1 or more. When an ultrafiltration membrane device has a plurality of ultrafiltration membrane modules, for example, it is preferable that the number of ultrafiltration membrane modules of an ultrafiltration membrane device (11x) in the upstream end and the number of ultrafiltration membrane modules of an ultrafiltration membrane device (12x) in the downstream end are the same. That is, it is preferable that the numbers of ultrafiltration membrane modules of the ultrafiltration membrane devices (11x and 12x) are the same, and the ultrafiltration membrane devices (11y and 12y) and the ultrafiltration membrane devices (11z and 12z) are also the same. In addition, it is preferable that the numbers of ultrafiltration membrane modules of the ultrafiltration membrane devices provided in the upstream end of each unit are the same. That is, it is also preferable that the numbers of ultrafiltration membrane modules of the ultrafiltration membrane devices (11x, 11y, 11z) are all the same. When the numbers of these ultrafiltration membrane modules are not the same, uneven flow may occur in which the flow rates of each unit or device are uneven, and there is a concern that the replacement cycle may be significantly shortened or the water quality may deteriorate.

(Embodiment 5)

Fig. 13 is a schematic diagram showing a configuration in which a single-stage ultrafiltration membrane device has multiple parallel ultrafiltration membrane modules. The secondary pure water production unit (13) shown in Fig. 13 has a first ultrafiltration membrane device (11) configured by connecting first ultrafiltration membrane modules (110p, 110q, 110r) in parallel, and a second ultrafiltration membrane device (12) configured by connecting second ultrafiltration membrane modules (120p, 120q, 120r) in parallel. In this configuration, the parallel-connected ultrafiltration membrane module groups of a single-stage ultrafiltration membrane device are combined into one, and between the ultrafiltration membrane module group on the upstream side (the ultrafiltration membrane module of the ultrafiltration membrane device (11)) and the ultrafiltration membrane module group on the downstream side (the ultrafiltration membrane module of the ultrafiltration membrane device (12)), new ultrafiltration membrane modules are arranged in the upstream side and used ultrafiltration membrane modules are arranged in the downstream side, thereby enabling replacement of ultrafiltration membrane modules and operation of the ultrafiltration membrane device. In addition, although Fig. 13 shows an embodiment in which one ultrafiltration membrane device has three ultrafiltration membrane modules connected in parallel, the number of ultrafiltration membrane modules connected in parallel may be two or four or more.

(Embodiment 6)

Figure 14 is a schematic diagram showing a configuration in which two or more ultrafiltration membrane units, each consisting of two ultrafiltration membrane devices connected in series, are connected in parallel, and a single ultrafiltration membrane device has a plurality of parallel ultrafiltration membrane modules.

The configuration according to Fig. 14 comprises an ultrafiltration membrane unit (17x) having a first ultrafiltration membrane device (11x) and a second ultrafiltration membrane device (12x), and an ultrafiltration membrane unit (17y) having a first ultrafiltration membrane device (11y) and a second ultrafiltration membrane device (12y) in parallel. In addition, the first ultrafiltration membrane device (11x) and the ultrafiltration membrane device (11y) are both configured by connecting first ultrafiltration membrane modules (110p, 110q, 110r) in parallel, and the second ultrafiltration membrane device (12x) and the ultrafiltration membrane device (12y) are both configured by connecting second ultrafiltration membrane modules (120p, 120q, 120r) in parallel.

In the configuration according to Fig. 14, the parallel-connected ultrafiltration membrane module groups of one ultrafiltration membrane device for each ultrafiltration membrane unit are combined into one, and new ultrafiltration membrane modules are placed in the upstream side and ultrafiltration membrane module groups in the downstream side, similarly to the first to third embodiments, between the ultrafiltration membrane module group in the upstream side and the ultrafiltration membrane module group in the downstream side, thereby enabling replacement of ultrafiltration membrane modules and operation of the ultrafiltration membrane device.

In the configuration where the above-described plurality of ultrafiltration membrane units are connected in parallel to a single ultrafiltration membrane device, the operating time after replacement with a new module is significantly shortened, so that high-quality ultra-pure water can be efficiently produced. In addition, the arrangement positions of the inlet, the permeate outlet, and the concentrated water outlet in the housings of the ultrafiltration membrane modules provided in the first ultrafiltration membrane device (11) and the second ultrafiltration membrane device (12) are each common to each other. Therefore, without changing the arrangement or shape of the piping of the ultra-pure water production system connected to the inlet, the permeate outlet, and the concentrated water outlet of the ultrafiltration membrane module, any ultrafiltration membrane module can be moved and replaced.

Example

Hereinafter, the present invention will be described in detail using examples. The present invention is not limited to the following examples.

(Example)

Raw water was treated by passing it sequentially from a raw water tank to a heat exchanger, an ultraviolet oxidation device (JPW-2, manufactured by Nippon Photoscience Co., Ltd.), a Pd-supported resin (Lewatit K7333, manufactured by LANXESS Co., Ltd.), a membrane degassing device (X40 G451H, manufactured by 3M Co., Ltd.), and a non-regenerative mixed-bed ion exchange device (200 L filled with N-Lite MBSP, manufactured by Nomura Micro Science). The treated water from the non-regenerative mixed-bed ion exchange device was passed sequentially to the first ultrafiltration membrane device and the second ultrafiltration membrane device. Ultrafiltration membrane devices (OLT-6036, manufactured by Asahi Kasei Co., Ltd.) having the same specifications (shape and properties of ultrafiltration membrane, shape of ultrafiltration membrane module, etc.) were used as the first ultrafiltration membrane device and the second ultrafiltration membrane device.

After the above raw water treatment was performed continuously for one year, the second ultrafiltration membrane device was replaced with a new one, and the liquid was passed through the new second ultrafiltration membrane device and the first ultrafiltration membrane device in that order for 20 hours of operation. The operation was performed by supplying ultrapure water to the heat exchanger. During the operation, the change in the number of fine particles having a diameter of 20 nm or more contained in the treated water of the first ultrafiltration membrane device over time was investigated. The number of fine particles was measured using a particle meter UltraDI-20 manufactured by Particle Measuring Systems. The results are shown in Fig. 15.

(Comparative example)

After continuously performing the treatment of raw water in the same manner as in the Example, the second ultrafiltration membrane device was replaced with a new one, and the first ultrafiltration membrane device and the new second ultrafiltration membrane device were passed in that order, and the operation was performed for 20 hours in the same manner as in the Example. In the same manner as in the Example, the change over time in the number of fine particles having a diameter of 20 nm or more contained in the treated water of the second ultrafiltration membrane device during the operation was investigated. The results are shown in Fig. 15 together with the Example. In Fig. 15, black squares represent Examples and white squares represent Comparative Examples.

It can be seen from the examples and comparative examples that the operating time can be shortened by placing a new ultrafiltration membrane module in the front end and placing a used ultrafiltration membrane module over time in the back end.

11, 12: Ultrafiltration membrane device, 13, 131: Secondary pure water production unit, 14: Pretreatment unit, 15: Primary pure water production unit, 16: Point of use (POU), 18: Particulate system, 110: First ultrafiltration membrane module, 120: Second ultrafiltration membrane module, 11a, 12a: Inlet, 11b, 12b: Permeate outlet, 11c, 12c: Concentrated water outlet, 111, 121: Untreated water supply pipe, 112, 122: Permeate outlet pipe, 113, 123: Ultrapure water pipe, 114, 124: Concentrated water outlet pipe, 115, 125: Transfer pipe

Claims (10)

A primary pure water manufacturing unit that manufactures primary pure water having a particle diameter of 20㎚ or more and a particle count of 100,000pcs./L or less, and
An ultrapure water manufacturing system having a secondary pure water manufacturing section for manufacturing ultrapure water having a particle diameter of 20㎚ or more and a particle count of 1000pcs./L or less by processing the primary pure water,
The above secondary pure water production unit has a plurality of ultrafiltration membrane modules connected in series,
The above multiple ultrafiltration membrane modules
A first ultrafiltration membrane module having a first inlet for introducing treated water into the inside, a first permeate outlet for discharging permeate, and a first concentrated water outlet for discharging concentrated water, and accommodating a first ultrafiltration membrane inside the module,
A second ultrafiltration membrane module having a second inlet for introducing treated water therein, a second permeate outlet for discharging permeate, and a second concentrated water outlet for discharging concentrated water, and accommodating a second ultrafiltration membrane therein,
The shape and size of the first ultrafiltration membrane module and the second ultrafiltration membrane module are common, and each of the first inlet and the second inlet, the first permeate outlet and the second permeate outlet, the first concentrated water outlet and the second concentrated water outlet are arranged at a common position within each module, and further, the first ultrafiltration membrane and the second ultrafiltration membrane have a common molecular weight cutoff and/or effective membrane area,
An ultrapure water production system configured so that the flow path of the treated water can be changed by reconnecting the pipe connecting the first flow path that sequentially flows from the first ultrafiltration membrane module to the second ultrafiltration membrane module and the second flow path that sequentially flows from the second ultrafiltration membrane module to the first ultrafiltration membrane module or by switching the valve of the pipe. delete In paragraph 1,
An ultrapure water production system, wherein the shapes and sizes of the plurality of ultrafiltration membrane modules are all common, and the plurality of ultrafiltration membrane modules have an inlet, a permeate outlet, and a concentrated water outlet all arranged in common positions. In claim 1 or 3,
An ultrapure water production system in which the above plurality of ultrafiltration membrane modules all have the same molecular weight cutoff and effective membrane area. In claim 1 or 3,
A first permeate outlet pipe connected to the first permeate outlet,
A first transfer pipe and a first ultrapure water pipe branched and connected from the first permeate outlet pipe,
Two opening/closing valves, each installed in the first transfer pipe and the first ultrapure water pipe, capable of switching the flow path of the permeate from the first permeate outlet pipe to the first transfer pipe and the first ultrapure water pipe,
A second permeate outlet pipe connected to the second permeate outlet,
A second transfer pipe and a second ultrapure water pipe branched and connected to the second permeate outlet pipe,
Two opening/closing valves, each installed in the second transfer pipe and the second ultra-pure water pipe, capable of switching the flow path of the permeate from the second permeate outlet pipe to the second transfer pipe and the second ultra-pure water pipe,
A first treatment water supply pipe connected to the first introduction port,
A second treatment water supply pipe connected to the second introduction port,
It has two opening/closing valves installed in the first treatment water supply pipe and the second treatment water supply pipe and capable of switching the supply path of the treatment water to the first treatment water supply pipe and the second treatment water supply pipe.
The above first transfer pipe is connected to the second treatment water supply pipe,
The above second transport pipe is connected to the above first treatment water supply pipe,
By the combination of opening and closing of the above six opening/closing valves
An ultrapure water production system configured to be switchable between a first flow path for flowing the treated water from the first ultrafiltration membrane module to the second ultrafiltration membrane module and a second flow path for flowing the treated water from the second ultrafiltration membrane module to the first ultrafiltration membrane module. In paragraph 5,
Instead of the above two on-off valves of the combination capable of switching the above-mentioned flow, a single three-way valve capable of switching two flow paths is provided at the branch point of the branched and connected pipe.
By the above three-way valve,
An ultrapure water production system configured to be switchable between a first flow path for flowing the treated water from the first ultrafiltration membrane module to the second ultrafiltration membrane module and a second flow path for flowing the treated water from the second ultrafiltration membrane module to the first ultrafiltration membrane module. In claim 1 or 3,
A first permeate outlet pipe connected to the first permeate outlet,
A first treatment water supply pipe connected to the first introduction port,
A second permeate outlet pipe connected to the second permeate outlet,
A second treatment water supply pipe connected to the second introduction port,
A treatment water pipe that supplies treatment water to the first treatment water supply pipe or the second treatment water supply pipe,
An ultrapure water pipe that sends the permeate from the first permeate outlet pipe or the second permeate outlet pipe to a place where ultrapure water is used,
A transfer pipe for transferring the permeate of the first ultrafiltration membrane module to the second untreated water supply pipe or the permeate of the second ultrafiltration membrane module to the first untreated water supply pipe;
A first flow path switching unit capable of switching the flow path of the treated water from the above-mentioned treated water pipe to the first treated water supply pipe and the second treated water supply pipe,
A second flow path switching unit that can switch the flow path of the ultrafiltration membrane permeate introduced into the above ultrapure water pipe to the first permeate outlet pipe and the second permeate outlet pipe,
A third flow path switching unit capable of switching the flow path of the permeate from the above-mentioned transfer pipe to the first treatment water supply pipe and the second treatment water supply pipe;
It has a fourth flow path switching section that can switch the flow path of the permeate introduced into the above-mentioned transport pipe to the first permeate outlet pipe and the second permeate outlet pipe,
An ultrapure water production system configured so that the flow path of the treated water can be switched by switching the first to fourth flow path switching sections, into a first flow path that flows from the first ultrafiltration membrane module to the second ultrafiltration membrane module, and a second flow path that flows from the second ultrafiltration membrane module to the first ultrafiltration membrane module. In paragraph 7,
Instead of the combination of each of the first and third euro switching sections and the second and fourth euro switching sections, there are two four-way valves having at least two euros inside and capable of switching their connections.
By the above 4-way valve,
An ultrapure water production system configured to be capable of switching the flow path of treated water into a first flow path that flows from the first ultrafiltration membrane module to the second ultrafiltration membrane module and a second flow path that flows from the second ultrafiltration membrane module to the first ultrafiltration membrane module. A primary pure water manufacturing unit that manufactures primary pure water having a particle diameter of 20㎚ or more and a particle count of 100,000pcs./L or less, and
A method for operating an ultrapure water manufacturing system having a secondary pure water manufacturing unit that manufactures ultrapure water having a particle diameter of 20㎚ or more and a particle count of 1000pcs./L or less by processing the primary pure water,
The above secondary pure water production unit has a plurality of ultrafiltration membrane modules connected in series, and the molecular weight fraction and/or effective membrane area of the ultrafiltration membrane of the ultrafiltration membrane module in the front stage and the ultrafiltration membrane of the ultrafiltration module in the back stage are common,
In the production of ultrapure water, the ultrafiltration membrane module at the rear end of the plurality of ultrafiltration membrane modules processes the permeate from the ultrafiltration membrane module at the front end,
When replacing at least one of the above multiple ultrafiltration membrane modules,
In the above ultrapure water production process, the ultrafiltration membrane module at the rear end is replaced with a new ultrafiltration membrane module.
An operating method of an ultrapure water manufacturing system, which operates the ultrapure water manufacturing system by switching the flow path with the above-mentioned new ultrafiltration membrane module as the front end and the ultrafiltration membrane module that is not to be replaced as the rear end, and by passing cleaning water through the above-mentioned plurality of ultrafiltration membrane modules. In Article 9,
Replacement of the above ultrafiltration membrane module
An operating method of an ultrapure water manufacturing system, which is performed when the number of fine particles having a diameter of 20 nm or more contained in the permeate of the ultrafiltration membrane module at the latter stage of the ultrapure water manufacturing process becomes 1000 pcs./L or more.