JP6070345B2 - Reverse osmosis membrane separator - Google Patents

Description

  The present invention relates to a reverse osmosis membrane separation device including a reverse osmosis membrane module that separates permeate from supply water.

  High-purity pure water that does not contain impurities is used in the manufacture of pharmaceuticals and cosmetics, the cleaning of electronic parts and precision equipment, and the like. This type of pure water is generally treated by reverse osmosis membrane treatment of raw water (hereinafter also referred to as “supply water”) such as ground water and tap water with a reverse osmosis membrane module (hereinafter also referred to as “RO membrane module”). Manufactured by. Conventionally, a reverse osmosis membrane separation device for producing pure water by treating supplied water with an RO membrane module has been proposed (see, for example, Patent Document 1).

JP 2009-279472 A

  By the way, in the RO membrane module using the spiral type element, in order to prevent the membrane surface from being blocked by an organic component or a suspended substance, a separation operation by a cross flow method is usually employed. In this cross-flow method, a separation operation is performed by applying a pressure higher than the osmotic pressure of the feed water to the primary side of the membrane while circulating the feed water at a flow rate more than 5 times the flow rate of the permeated water by a pressure pump I do. At this time, since the supply water flowing out from the RO membrane module is concentrated water, the circulation ratio defined by the ratio of the flow rate of the concentrated water to the flow rate of the permeated water is maintained at 5 or more.

  In order to maintain the circulation ratio at 5 or more, it is necessary to provide a pressurizing pump with a large discharge amount and discharge pressure, but such a pressurizing pump consumes a large amount of power because it drives a large capacity motor. . Here, the condition of the circulation ratio described above is set on the assumption that the suspended water is contained in the supply water. For this reason, it is considered that the circulation ratio can be reduced and the power consumption of the pressurizing pump can be suppressed by using appropriately purified supply water.

  An object of this invention is to provide the reverse osmosis membrane separator which can suppress power consumption in operation | movement of a pressurization pump.

The present invention includes at least one reverse osmosis membrane module that separates supply water into permeated water and concentrated water, a pressure pump that discharges supply water toward the reverse osmosis membrane module, and supply water and concentrated water. at least a water quality detection means for detecting one of the water quality, when the ratio of the flow rate of the concentrated water to the flow rate of pre Kigyaku osmosis membrane permeated water separated by the module was circulation ratio in the reverse osmosis membrane module, the quality of According to the water quality detected by the detection means, the flow rate of the feed water, the flow rate of the permeated water, and the flow rate of the concentrated water are adjusted so that the circulation ratio in the reverse osmosis membrane module falls within a predetermined circulation ratio range. a control unit to set the at least one relates to reverse osmosis membrane separation device comprising a.

The control unit is configured such that a predetermined circulation ratio is within the range specified in the 2-10, that you set the flow rate of the feed water, the flow rate of the permeate, and at least one of the flow rate of the concentrated water Is preferred.

The control unit may decrease the circulation ratio when the water quality detected by the water quality detection means is improved, or increase the circulation ratio when the water quality detected by the water quality detection means is reduced. as such, the flow rate of the feed water, the flow rate of the permeate, and that you set at least one of the flow rate of the concentrated water is preferred.

  The water quality detection means includes a turbidity detection sensor for detecting turbidity of either supply water or concentrated water, an iron concentration detection sensor for detecting iron concentration of either supply water or concentrated water, and supply water and concentration. It is preferably any one or more of all organic carbon detection sensors that detect any organic carbon in water.

  ADVANTAGE OF THE INVENTION According to this invention, the reverse osmosis membrane separation apparatus which can suppress power consumption in operation | movement of a pressurization pump can be provided.

1 is an overall schematic diagram of a pure water production apparatus 1 according to a first embodiment. It is the front | former part of the whole block diagram of the pure water manufacturing apparatus 1 which concerns on 1st Embodiment. It is the middle stage part of the whole block diagram of the pure water manufacturing apparatus 1 which concerns on 1st Embodiment. It is a back | latter stage part of the whole block diagram of the pure water manufacturing apparatus 1 which concerns on 1st Embodiment. 5 is a flowchart showing a processing procedure when flow rate feedback water amount control is executed in the control unit 30. It is a flowchart which shows the process sequence in the case of performing water quality feedforward collection | recovery rate control in the control part 30. FIG. 3 is a flowchart showing a processing procedure when control for adjusting a circulation ratio is executed in a control unit 30. It is the whole schematic diagram of the pure water manufacturing apparatus 1A which concerns on 2nd Embodiment. It is the 1st middle stage part of the whole block diagram of the pure water manufacturing apparatus 1A which concerns on 2nd Embodiment. It is the 2nd middle stage part of the whole block diagram of the pure water manufacturing apparatus 1A which concerns on 2nd Embodiment. It is a back | latter stage part of the whole block diagram of the pure water manufacturing apparatus 1A which concerns on 2nd Embodiment.

Hereinafter, an embodiment when a reverse osmosis membrane separation device according to the present invention is applied to a pure water production device will be described.
(First embodiment)
First, the pure water manufacturing apparatus 1 which concerns on 1st Embodiment is demonstrated, referring drawings. FIG. 1 is an overall schematic diagram of a pure water production apparatus 1 according to the first embodiment. FIG. 2A is a front part of the overall configuration diagram of the pure water producing apparatus 1 according to the first embodiment. FIG. 2B is a middle part of the entire configuration diagram of the pure water producing apparatus 1 according to the first embodiment. FIG. 2C is a rear part of the entire configuration diagram of the pure water producing apparatus 1 according to the first embodiment. The pure water production apparatus 1 according to the present embodiment is applied to, for example, a pure water production apparatus that produces demineralized water (deionized water) from raw water (for example, tap water). The desalinated water produced by the pure water production apparatus 1 is sent as pure water to a demand location or the like. In the pure water production apparatus 1 according to the present embodiment, supplying pure water to a demand point or the like is also referred to as “water sampling”.

  As shown in FIG. 1, the pure water manufacturing apparatus 1 according to the first embodiment includes a first optional device OP1, a prefilter 4, a second optional device OP2, a pressurizing pump 5, an inverter 6, and a reverse RO membrane module 7 as the osmotic membrane module, third optional device OP3, first flow path switching valve V71, electrodeionization stack (hereinafter also referred to as “EDI stack”) 16, and second flow path switching valve V72, 4th option apparatus OP4, the control part 30, the input operation part 40, the DC power supply device 50, and the display part 60 are provided.

  The first option device OP <b> 1 to the fourth option device OP <b> 4 are devices installed in the pure water production apparatus 1 as optional equipment that can be attached to and detached from the pure water production apparatus 1. The first optional device OP1 includes a water softener 2 and a filtration processing device 3. The first optional device OP1 functions as a pretreatment device that removes (pretreatments) various impurities contained in the raw water W11 in advance. The second optional device OP2 includes a hardness sensor S1, a residual chlorine sensor S2, a turbidity sensor S3 as water quality detection means, an iron concentration sensor S4 as water quality detection means, and a first TOC sensor as water quality detection means (total organic carbon sensor). Includes TOC1. The third optional device OP3 includes a decarboxylation device 15. The fourth optional device OP4 includes a second specific resistance sensor RS2, a second TOC sensor TOC2, and a third temperature sensor TE3.

  In addition, as shown in FIG. 1, the pure water production apparatus 1 includes a supply water line L1, a permeate water line L21, an RO permeate return line L41, an RO concentrated water return line L51, and a desalted water line L3. A demineralized water return line L42, an EDI concentrated water line L52, and a water supply line L4 are provided. The “line” in the present specification is a general term for lines capable of flowing a fluid such as a flow path, a radial path, and a pipeline.

  2A to 2C, in addition to the configuration shown in FIG. 1, the pure water production apparatus 1 includes a first on-off valve V11 to a seventh on-off valve V17, a vacuum breaker valve V41, and a pressure reducing valve V42. A supply water supply valve V31, a first drain valve V32 to a third drain valve V34, a proportional control valve V50, a first constant flow valve V51 to a fourth constant flow valve V54, and a first check valve V61 to the first. 5 check valve V65, first pressure gauge P1 to sixth pressure gauge P6, first pressure sensor PS1 to fourth pressure sensor PS4, pressure switch PSW, first temperature sensor TE1 and second temperature sensor TE2 The first flow sensor FM1 and the second flow sensor FM2, the first electrical conductivity sensor EC1, and the first specific resistance sensor RS1.

  In FIG. 1 and FIG. 2A to FIG. 2C, the electrical connection path is omitted, but the control unit 30 includes the supply water replenishment valve V31, the first flow path switching valve V71, the second flow path switching valve V72, and the first. Drain valve V32 to third drain valve V34, pressure switch PSW, hardness sensor S1, residual chlorine sensor S2, turbidity sensor S3, iron concentration sensor S4, first TOC sensor TOC1, first temperature sensor TE1 to third temperature sensor TE3, 1st pressure sensor PS1-4th pressure sensor PS4, 1st flow sensor FM1 and 2nd flow sensor FM2, 1st electric conductivity sensor EC1, 1st specific resistance sensor RS1, 2nd specific resistance sensor RS2, 2nd TOC sensor TOC2 Etc. are electrically connected.

First, the front part of the overall configuration diagram in the pure water production apparatus 1 will be described.
As shown in FIGS. 1 and 2A, the supply water W1 flows through the supply water line L1. The supply water line L1 is a line through which the supply water W1 is circulated to the RO membrane module 7. The supply water line L1 includes a first supply water line L11 and a second supply water line L12.

  The raw water W11 (supply water W1) flows through the first supply water line L11. The first supply water line L11 is a line that connects a supply source (not shown) of the raw water W11 and the water softener 2. The upstream end of the first supply water line L11 is connected to a supply source (not shown) of the raw water W11. Further, the downstream end of the first supply water line L <b> 11 is connected to the water softener 2.

  As shown in FIG. 2A, the first supply water line L11 is provided with a connecting portion J1, a first on-off valve V11, and a water softener 2 in order from the upstream side. The first on-off valve V11 is a manual valve that can be operated to open and close the first supply water line L11.

  The water softener 2 is an apparatus that manufactures the soft water W12 (feed water W1) by replacing the hardness component contained in the raw water W11 with sodium ions. The water softener 2 has an ion exchange tower containing a cation exchange resin bed in a pressure tank.

  Soft water W12 (supply water W1) flows through the second supply water line L12. The second supply water line L12 is a line through which the soft water W12 is circulated to the RO membrane module 7. The second supply water line L <b> 12 is a line that connects the water softener 2 and the RO membrane module 7. As shown in FIG. 2A, the upstream end of the second supply water line L <b> 12 is connected to the water softener 2. As shown in FIG. 2B, the downstream end of the second supply water line L12 is connected to the primary inlet port (inlet for the supply water W1) of the RO membrane module 7.

  As shown in FIG. 2A, in order from the upstream side, the second on-off valve V12, the connecting portion J2, the third on-off valve V13, the filtration device 3, the fourth on-off valve V14, and the connecting portion are connected to the second supply water line L12. J3, the prefilter 4, the connection part J4, and the connection part J5 are provided. Further, after the connecting portion J5, as shown in FIG. 2B, the fifth on-off valve V15, the connecting portion J6, the pressure reducing valve V42, the supply water replenishing valve V31, the connecting portion J59, the connecting portion J51, the connecting portion J7, and the connecting portion. J8, pressurizing pump 5, connecting portion J9, and RO membrane module 7 are provided. The second on-off valve V12 to the fifth on-off valve V15 are manual valves that can be operated to open and close the second supply water line L12. The supply water supply valve V31 is a valve that can control the opening and closing of the second supply water line L12. The supply water supply valve V31 is electrically connected to the control unit 30. The opening and closing of the supply water replenishing valve V31 is controlled by a flow path opening / closing signal transmitted from the control unit 30.

  The filtration apparatus 3 captures and removes suspended matter contained in the soft water W12 (feed water W1). The filtration apparatus 3 is variously selected according to the substance to be removed in the soft water W12 (feed water W1). Examples of the filtration treatment device 3 include a sand filtration device, an iron removal manganese removal device, and an activated carbon filtration device. In addition, the filtration processing apparatus 3 may have a configuration in which all of the sand filtration apparatus, the iron removal manganese removal apparatus, and the activated carbon filtration apparatus do not exist, and is configured by any one or more of the sand filtration apparatus, the iron removal manganese removal apparatus, and the activated carbon filtration apparatus. All of them may be connected in series and used in combination, or may be used alone.

  The sand filtration device captures and removes suspended substances such as fine particles contained in the soft water W12 (feed water W1) by the filter medium bed. Examples of the sand filtration device include a tower type having a filtration tower containing a filter medium bed formed from coarse filter media such as meteorite and fine filter media such as anthracite and filter sand.

  The iron removal manganese removal apparatus captures and removes dissolved iron and dissolved manganese contained in the soft water W12 (feed water W1) by the filter medium bed. The iron removal manganese removal apparatus has, for example, a filtration tower that accommodates the filter medium bed. Usually, particulate manganese chamotte or manganese zeolite is used for the filter medium.

  The activated carbon filter is a device that removes chlorine components (mainly free residual chlorine) contained in the soft water W12 (feed water W1). The activated carbon filtration device has a filtration tower in which a filter medium bed made of activated carbon is accommodated in a pressure tank. The activated carbon filtration device purifies the soft water W12 (feed water W1) by decomposing and removing chlorine components contained in the soft water W12, adsorbing and removing organic components, and capturing suspended substances.

  The pre-filter 4 is a filter that removes fine particles contained in the soft water W12 (supply water W1) purified by the filtration processing device 3. The prefilter 4 is configured by accommodating a filter element in a housing. As the filter element, for example, a nonwoven fabric filter element or a thread-wound filter element having a filtration accuracy of 1 to 50 μm is used.

  In the supply water line L1, the water quality items of the pretreatment water produced by the filtration device 3 (sand filter device, iron removal manganese removal device, activated carbon filter device) are turbidity, iron concentration and residual chlorine concentration, respectively. The quality of the pretreated water can be determined based on these water quality items. Further, the quality of the pretreated water may be determined by combining not only one item among the plurality of items described above but also a plurality of items. In the present embodiment, a hardness sensor S1, a residual chlorine sensor S2, a turbidity sensor S3, an iron concentration sensor S4, and a second TOC sensor TOC2 are connected to the supply water line L1 in order to determine the quality of the pretreatment water. ing.

  The hardness sensor S1 is a device that measures the total hardness (that is, the hardness leak amount) of the supply water W1 flowing through the supply water line L1. The residual chlorine sensor S2 is a device that measures the free residual chlorine concentration (that is, chlorine leak amount) of the supply water W1 flowing through the supply water line L1.

  The turbidity sensor S3 is a device that detects the turbidity (turbidity leak amount) of the supply water W1 flowing through the supply water line L1. The turbidity sensor S3 can detect a turbidity leak from the sand filtration device when a sand filtration device is provided as the filtration processing device 3, for example. The turbidity of the supply water W1 is one of the water quality items related to the causative substance of the fouling of the RO membrane module 7. When the turbidity of the supply water W1 deteriorates, the RO membrane is blocked due to the occurrence of fouling. Turbidity is defined in JIS K0101 “Industrial Water Test Method”. “Turbidity represents the degree of turbidity of water. It is classified into visual turbidity, transmitted light turbidity, scattered light turbidity, and integrating sphere turbidity. Display. " As the turbidity sensor S3, for example, as shown in JIS K0101, a transmitted light sensor that determines the turbidity of sample water from the transmitted light intensity, a scattered light sensor that determines from the scattered light intensity, An integrating sphere sensor or the like determined from the ratio of scattered light intensity and transmitted light intensity can be used.

  The iron concentration sensor S4 is a device that detects the total iron concentration (iron leakage amount) of the supply water W1 flowing through the supply water line L1. The iron concentration sensor S4 can detect a leakage of iron from the iron removal manganese removal apparatus when, for example, a iron removal manganese removal apparatus is provided as the filtration processing device 3. The total iron concentration in the feed water W1 can be measured according to the quantification of iron in JIS K0101 “Industrial Water Test Method”. As the iron concentration sensor S4, for example, a phenanthroline absorptiometric sensor that measures absorbance after adding phenanthroline, as shown in JIS K0101, can be used.

  The first TOC sensor TOC1 is a device that detects the total organic carbon amount (TOC leak amount) of the supply water W1 that flows through the supply water line L1. Total organic carbon (TOC: Total Organic Carbon) is said to be “refers to carbon in organic matter present in water” in JIS K0101 “Industrial Water Test Method”. As the first TOC sensor TOC1, for example, a UV oxidation-electric conductivity measurement type sensor or the like can be used.

  As shown in FIG. 2A, the hardness sensor S1, the residual chlorine sensor S2, the turbidity sensor S3, the iron concentration sensor S4, and the first TOC sensor TOC1 are connected to the supply water line L1 at the connection portion J5 via the measurement line L110. ing. The connecting part J5 is disposed between the prefilter 4 and the fifth on-off valve V15 in the supply water line L1. The hardness sensor S1, the residual chlorine sensor S2, the turbidity sensor S3, the iron concentration sensor S4, and the first TOC sensor TOC1 are electrically connected to the control unit 30. Hardness leak amount measured by hardness sensor S1, chlorine leak amount measured by residual chlorine sensor S2, turbidity leak amount of feed water W1 detected by turbidity sensor S3 (hereinafter also referred to as “measured turbidity”) , The iron leakage amount of the feed water W1 measured by the iron concentration sensor S4 (hereinafter also referred to as “measured iron concentration”) and the TOC leak amount of the feed water W1 measured by the first TOC sensor TOC1 (hereinafter referred to as “measured TOC value”). Is also transmitted to the control unit 30 as a detection signal.

Next, the middle part of the overall configuration diagram in the pure water production apparatus 1 will be described.
As shown in FIG. 2B, a vacuum breaker valve V41 is connected to the connecting portion J6. The vacuum breaker valve V41 is a normally closed pressure operating valve, and when the pressure inside the supply water line L1 becomes lower than the atmospheric pressure, the valve body opens and sucks air. By providing the vacuum breaker valve V41, even if the raw water W11 (feed water W1) is cut off and the feed water line L1 becomes negative pressure, it is possible to prevent problems such as damage to the membrane of the RO membrane module 7. it can.

  The pressure reducing valve V42 is a device that adjusts the pressure of the soft water W12 that has passed through the water softener 2, the activated carbon filter 3, and the prefilter 4 to a pressure lower than the pressure of the concentrated water W3 flowing out from the RO membrane module 7. The pressure reducing valve V42 adjusts the pressure of the soft water W12 so that the pressure of the concentrated water W3 is larger than the pressure of the soft water W12 (pressure of the soft water W12 <pressure of the concentrated water W3). Thereby, a part of the concentrated water W3 is circulated to the soft water W12, and the supply water in which the concentrated water W3 is mixed with the soft water W12 is supplied to the RO membrane module 7. That is, in the RO membrane module 7, a cross-flow type separation operation for producing permeated water is performed while circulating the supply water by the pressure pump 5.

  The downstream end of the desalted water return line L42 described later is connected to the connecting portion J59. The connecting portion J51 is connected to the downstream end portion of the RO permeate return line L41, which will be described later, and the downstream end portion of the RO concentrated water return line L51.

  The pressurizing pump 5 is a device that sucks in the supply water W1 flowing through the supply water line L1 and pumps (discharges) it toward the RO membrane module 7. The pressurizing pump 5 is supplied with driving power whose frequency is converted from the inverter 6. The pressurizing pump 5 is driven at a rotational speed corresponding to the frequency of the supplied driving power (hereinafter also referred to as “driving frequency”).

  The inverter 6 is an electric circuit (or a device having the circuit) that supplies driving power whose frequency is converted to the pressure pump 5. The inverter 6 is electrically connected to the control unit 30. A command signal is input to the inverter 6 from the control unit 30. The inverter 6 outputs driving power having a driving frequency corresponding to the command signal (current value signal or voltage value signal) input by the control unit 30 to the pressurizing pump 5.

  The RO membrane module 7 separates the supply water W1 pumped by the pressurizing pump 5 into permeate water W2 from which dissolved salts have been removed and concentrated water W3 from which dissolved salts have been concentrated. The RO membrane module 7 is configured by accommodating a single or a plurality of spiral RO membrane elements in a pressure vessel (vessel). Examples of the RO membrane used in the RO membrane element include a crosslinked aromatic polyamide composite membrane. Examples of RO membrane elements composed of a crosslinked aromatic polyamide composite membrane include: Toray Industries, Inc .: model name “TMG20-400”, Eunjin Chemical Co., Ltd .: model name: “RE8040-BLF”, Nitto Denko Corporation: model name: “ESPA1” Are commercially available, and these elements can be suitably used.

  The RO concentrated water return line L51 is a line for returning a part W31 of the concentrated water W3 separated by the RO membrane module 7 to the supply water line L1. The upstream end of the RO concentrated water return line L51 is connected to the primary outlet port (the outlet of the concentrated water W3) of the RO membrane module 7. The downstream end of the RO concentrated water return line L51 is connected to the supply water line L1 at the connection J51. The RO concentrated water return line L51 is provided with a first check valve V61 and a proportional control valve V50.

  The proportional control valve V50 is a valve that adjusts the flow rate (circulation flow rate) of the concentrated water W3 returned to the RO concentrated water return line L51. The proportional control valve V50 is electrically connected to the control unit 30. The valve opening degree of the proportional control valve V50 is controlled by a drive signal transmitted from the control unit 30. The circulating flow rate of the concentrated water W3 can be adjusted by transmitting a current value signal (for example, 4 to 20 mA) from the control unit 30 to the proportional control valve V50 and controlling the valve opening degree. By this adjustment, the circulation ratio R of the RO membrane module 7 can be kept at a preset value. The circulation ratio R of the RO membrane module 7 is the ratio of the flow rate of the permeated water W2 flowing out from the secondary side port of the RO membrane module and the flow rate of the concentrated water W3 flowing out from the primary side outlet port (of the concentrated water W3 (Flow rate / flow rate of permeated water W2).

  Regarding the circulation ratio R, when the RO membrane of the RO membrane module 7 is used, there is a circulation ratio recommended by the manufacturer of the RO membrane element. In the manufacturer's recommended value, during normal operation, the circulation ratio R of the frontmost RO membrane module is approximately 5 as a guide. Note that the manufacturer recommended value of the circulation ratio R varies depending on the type of membrane. For example, the manufacturer recommended value of the circulation ratio R varies depending on the ultrafiltration membrane (UF membrane), microfiltration membrane (MF membrane), nanofiltration membrane (NF membrane), and reverse osmosis membrane (RO membrane).

  The RO concentrated water discharge line L61 is a line for discharging the remaining portion W32 of the concentrated water W3 separated by the RO membrane module 7 from the middle of the RO concentrated water return line L51 to the outside of the apparatus. The upstream end portion of the RO concentrated water discharge line L61 is connected to the connection portion J53. The connecting portion J53 is disposed between the RO membrane module 7 and the connecting portion J52 in the RO concentrated water return line L51. The upstream end portions of the first concentrated water drain line L611, the second concentrated water drain line L612, and the third concentrated water drain line L613 are connected to the RO concentrated water discharge line L61 at the connecting portions J55 and J56.

  The first concentrated water drain line L611 to the third concentrated water drain line L613 are provided with a first drain valve V32 to a third drain valve V34, and a first constant flow valve V51 to a third constant flow valve V53, respectively. Yes. The first constant flow valve V51 to the third constant flow valve V53 are set to different flow values. The first drainage valve V32 to the third drainage valve V34 can individually open and close the first concentrated water drainage line L611 to the third concentrated water drainage line L613. By appropriately selecting the number of the first drain valve V32 to the third drain valve V34 that are opened, the drainage flow rate of the concentrated water W3 discharged to the outside of the apparatus can be adjusted. By this adjustment, the recovery rate of the permeated water W2 can be maintained at a preset value. The recovery rate of the permeated water W2 is the ratio (%) of the permeated water W2 to the flow rate of the soft water W12 supplied to the RO membrane module 7 (the supplied water W1 before the part W31 of the concentrated water W3 is mixed). Say.

  The first drain valve V32 to the third drain valve V34 are electrically connected to the control unit 30, respectively. Opening and closing of the first drain valve V32 to the third drain valve V34 is controlled by a drive signal transmitted from the control unit 30.

  The downstream ends of the first concentrated water drainage line L611, the second concentrated water drainage line L612, and the third concentrated water drainage line L613 are connected to the upstream end of the merged drainage line L62 at the connecting portions J57 and J58. Has been. The downstream end portion of the combined drainage line L62 is connected or opened to a drainage pit (not shown), for example. A second check valve V62 is provided in the middle of the combined drainage line L62.

  The permeated water line L <b> 21 is a line through which the permeated water W <b> 2 separated by the RO membrane module 7 flows through the EDI stack 16. As shown in FIGS. 2B and 2C, the permeate water line L21 includes a front-stage permeate water line L211, a middle-stage permeate water line L212, a desalting chamber inflow line L213, and a concentration chamber inflow line L214.

  As shown in FIG. 2B, the upstream end of the front-stage permeate line L211 is connected to the secondary port (the outlet of the permeate W2) of the RO membrane module 7. As shown in FIG. 2C, the downstream end of the front-stage permeate line L211 is connected to the middle-stage permeate line L212 and the RO permeate return line L41 via the first flow path switching valve V71. .

  As shown in FIG. 2B, a upstream side permeate line L211 is provided with a third check valve V63, a connection portion J10, a connection portion J11, and a sixth on-off valve V16 in order from the upstream side. Further, after the sixth on-off valve V16, as shown in FIG. 2C, a decarboxylation device 15, a connection portion J31, a connection portion J32, and a first flow path switching valve V71 are provided. The 6th on-off valve V16 is a manual valve which can operate opening and closing of the front | former stage side permeated water line L211.

Next, the latter part of the entire configuration diagram in the pure water production apparatus 1 will be described.
In FIG. 2C, the decarboxylation device 15 is a facility that obtains degassed water (degassed permeated water) by degassing the free carbonic acid (dissolved carbon dioxide gas) contained in the permeated water W2 with a gas separation membrane module. . By providing the decarboxylation device 15 on the downstream side of the RO membrane module 7, free carbon dioxide that easily permeates the RO membrane can be removed from the permeated water W <b> 2. Accordingly, it is possible to obtain the permeated water W2 having a higher purity. In the decarboxylation device 15 of the present embodiment, an external perfusion type gas separation membrane module made of a hollow fiber membrane is used, and a sweep gas such as air is introduced while the inside of the hollow fiber membrane is sucked by a vacuum pump (not shown). The free carbon dioxide is exhausted while being transferred into the sweep gas through the membrane wall. As a gas separation membrane module suitable for such an application, for example, a product name “Liqui-Cel G-521R” manufactured by Celgard Co., Ltd. may be mentioned. The vacuum pump connected to the gas separation membrane module is electrically connected to the control unit 30.

  The first flow path switching valve V71 is a flow path (water sampling side flow path) for flowing the permeated water W2 separated by the RO membrane module 7 toward the EDI stack 16 via the middle permeate water line L212. The automatic valve can be switched to a flow path (circulation-side flow path) that circulates toward the supply water line L1 on the upstream side of the RO membrane module 7 via the RO permeate return line L41. The first flow path switching valve V71 is configured by, for example, an electric or electromagnetic three-way valve. The first flow path switching valve V71 is electrically connected to the control unit 30. The switching of the flow path in the first flow path switching valve V71 is controlled by a flow path switching signal transmitted from the control unit 30.

  The RO permeated water return line L41 is a line that returns the permeated water W2 separated by the RO membrane module 7 to the supply water line L1 upstream of the RO membrane module 7. The upstream end of the RO permeate return line L41 is connected to the first flow path switching valve V71. The downstream end of the RO permeate return line L41 is connected to the RO concentrated water return line L51 at the connection J52. The connection part J52 is arrange | positioned between the connection part J53 and the connection part J51 in RO concentrated water return line L51. The portion from the connecting portion J52 to the connecting portion J51 in the RO permeate return line L41 is common to the portion from the connecting portion J52 to the connecting portion J51 in the RO concentrated water return line L51. A fourth check valve V64 is provided on the upstream side of the RO permeate return line L41.

  The upstream end of the middle permeate line L212 is connected to the first flow path switching valve V71. The downstream end of the middle permeate water line L212 is connected to the upstream end of the desalting chamber inflow line L213 and the upstream end of the concentrating chamber inflow line L214 at the branch J71.

  The downstream end of the desalting chamber inflow line L213 is connected to the primary port of the EDI stack 16 (inlet side of the desalting chamber 161). A connecting portion J33 is disposed in the desalting chamber inflow line L213. The downstream end of the concentrating chamber inflow line L214 is connected to a primary port (each inlet side of the concentrating chamber 162) of the EDI stack 16. The concentrating chamber inflow line L214 is provided with a fourth constant flow valve V54 and a connecting portion J34 in order from the upstream side.

  The EDI stack 16 is a water treatment device that obtains demineralized water W6 (deionized water) and concentrated water W7 by demineralizing the permeated water W2 separated by the RO membrane module 7 (deionized treatment). The EDI stack 16 is electrically connected to a DC power supply device 50 (see FIG. 1). A DC voltage is applied to the EDI stack 16 from the DC power supply device 50. The EDI stack 16 is energized by the DC voltage applied from the DC power supply device 50 and operates.

  The DC power supply device 50 applies a DC voltage between the pair of electrodes of the EDI stack 16. The DC power supply device 50 is electrically connected to the control unit 30. The DC power supply device 50 outputs a DC voltage to the EDI stack 16 in response to the command signal input by the control unit 30.

  In the EDI stack 16, a cation exchange membrane and an anion exchange membrane (not shown) are alternately arranged between a pair of electrodes. The inside of the EDI stack 16 is partitioned into a desalting chamber 161 and a concentration chamber 162 (including an anode chamber and a cathode chamber) by these ion exchange membranes. The desalting chamber 161 is filled with an ion exchanger (not shown). As an ion exchanger filled in the desalting chamber 161, for example, an ion exchange resin or an ion exchange fiber is used. In FIG. 2C, a plurality of desalting chambers 161 and concentration chambers 162 partitioned inside the EDI stack 16 are schematically shown.

  A desalting chamber inflow line L213 through which the permeated water W2 flows is connected to the inlet side of the desalting chamber 161. On the outlet side of the desalting chamber 161, a desalted water line L3 through which the desalted water W6 discharged from the ions in the desalting chamber 161 is discharged is connected. A concentrating chamber inflow line L214 through which the permeated water W2 flows is connected to the inlet side of the concentrating chamber 162. An EDI concentrated water line L52 for circulating the concentrated water W7 that has been concentrated and discharged is connected to the outlet side of the concentration chamber 162.

  The permeated water W2 flowing through the permeated water line L21 flows into each of the desalting chamber 161 and the concentration chamber 162. Residual ions contained in the permeated water W2 are captured by an ion exchanger (not shown) filled in the desalting chamber 161 to become desalted water W6. The desalted water W6 is sent to the demand location via the desalted water line L3 (described later). Further, residual ions captured by the ion exchanger in the desalting chamber 161 move to the concentration chamber 162 by the electric energy of the applied DC voltage. And the water containing a residual ion is sent out toward the decarbonation apparatus 15 through the EDI concentrated water line L52 (after-mentioned) as the concentrated water W7. The concentrated water W7 sent to the decarboxylation device 15 is used as sealing water for the vacuum pump, and is then discharged out of the device via a sealing water discharge line L71 (described later).

  The desalted water line L3 is a line for sending the desalted water W6 obtained by the EDI stack 16 to the demand point as pure water. The demineralized water line L3 includes an upstream demineralized water line L31 and a downstream demineralized water line L32.

  The upstream end of the upstream demineralized water line L31 is connected to the secondary port of the EDI stack 16 (the outlet side of the demineralized chamber 161). The downstream end of the upstream demineralized water line L31 is connected to a downstream demineralized water line L32 and a demineralized water return line L42 (described later) via a second flow path switching valve V72. In the upstream demineralized water line L31, a connecting portion J36, a connecting portion J37, a connecting portion J38, a seventh on-off valve V17, and a second flow path switching valve V72 are provided in this order from the upstream side. The seventh on-off valve V17 is a manual valve that can be operated to open and close the upstream demineralized water line L31.

  The second flow path switching valve V72 is a flow path (water sampling side flow path) for sending the desalted water W6 obtained in the desalination chamber 161 of the EDI stack 16 toward the demand point via the downstream side desalted water line L32. ) Or an automatic valve that can be switched to a flow path (circulation side flow path) that circulates toward the supply water line L1 upstream of the RO membrane module 7 via the desalted water return line L42. The second flow path switching valve V72 is configured by, for example, an electric or electromagnetic three-way valve. The second flow path switching valve V72 is electrically connected to the control unit 30. The switching of the flow path in the second flow path switching valve V72 is controlled by a flow path switching signal transmitted from the control unit 30.

  The second flow path switching valve V72 is capable of executing a process of sending the desalted water W6 obtained in the EDI stack 16 from the desalted water line L3 to the demand point by being switched to the water sampling side flow path by the control unit 30. Functions as a means.

  The upstream end of the downstream demineralized water line L32 is connected to the second flow path switching valve V72. The downstream end of the downstream demineralized water line L32 is connected to an apparatus or the like (not shown) at the demand point.

  The desalted water return line L42 is a line that returns the desalted water W6 obtained in the desalting chamber 161 of the EDI stack 16 from the middle of the desalted water line L3 to the upstream side of the RO membrane module 7 (supply water line L1). is there. In the present embodiment, the upstream end of the desalted water return line L42 is connected to the second flow path switching valve V72. The downstream end of the desalted water return line L42 is connected to the connecting portion J59. A fifth check valve V65 is provided on the upstream side of the desalted water return line L42.

  The EDI concentrated water line L52 is a line for sending the concentrated water W7 discharged from the concentration chamber 162 of the EDI stack 16 to the decarboxylation device 15. The upstream end of the EDI concentrated water line L52 is connected to the secondary port of the EDI stack 16 (the outlet side of the concentration chamber 162). The downstream end of the EDI concentrated water line L52 is connected to the decarboxylation device 15.

  The sealed water discharge line L71 is a line for discharging the sealed water drainage W8 discharged from the decarboxylation device 15 to the outside of the device. The upstream end of the sealed water discharge line L71 is connected to the decarbonation device 15. The downstream side of the sealed water discharge line L71 is connected or opened to a drainage pit (not shown), for example.

  The first pressure gauge P1 to the sixth pressure gauge P6 are devices that measure the pressure of water flowing through each connected line. As shown in FIG. 2A, the first pressure gauge P1 to the fourth pressure gauge P4 are each connected to the supply water line L1 at the connection portions J1 to J4. As shown in FIG. 2C, the fifth pressure gauge P5 is connected to the EDI concentrated water line L52 at the connection portion J35. The sixth pressure gauge P6 is connected to the demineralized water line L3 at the connection portion J36.

  The first pressure sensor PS1 to the fourth pressure sensor PS4 are devices that measure the pressure of water flowing through each connected line. As shown in FIGS. 2B and 2C, the first pressure sensor PS1 is connected to the supply water line L1 at the connection portion J9. The connecting portion J9 is disposed between the pressurizing pump 5 and the RO membrane module 7 in the supply water line L1. The second pressure sensor PS2 is connected to the permeate line L21 at the connection portion J11. The connecting portion J11 is disposed between the RO membrane module 7 and the decarboxylation device 15 in the permeate line L21. The third pressure sensor PS3 is connected to the desalting chamber inflow line L213 at the connection portion J33. The connection part J33 is arrange | positioned in the middle of the desalination chamber inflow line L213. The fourth pressure sensor PS4 is connected to the concentration chamber inflow line L214 at the connection portion J34. The connection portion J34 is disposed between the fourth constant flow valve V54 and the EDI stack 16 in the concentration chamber inflow line L214.

  The first pressure sensor PS1 to the fourth pressure sensor PS4 are electrically connected to the control unit 30. The pressure of the supply water W1 or the permeated water W2 measured by the first pressure sensor PS1 to the fourth pressure sensor PS4 is transmitted to the control unit 30 as a detection signal.

  The pressure switch PSW is a device that detects that the pressure of the supply water W1 flowing through the supply water line L1 is equal to or lower than the first set pressure value or equal to or higher than the second set pressure value. As shown in FIG. 2B, the pressure switch PSW is connected to the supply water line L1 at the connection portion J7. The connection part J7 is arrange | positioned between the connection part J51 and the pressurization pump 5 in the supply water line L1. A detection signal of the pressure of the supply water W <b> 1 detected by the pressure switch PSW is transmitted to the control unit 30.

  The first temperature sensor TE1 to the third temperature sensor TE3 are devices that measure the temperature of water flowing through each connected line. The first temperature sensor TE1 is connected to the supply water line L1 at the connection portion J8. The connection part J8 is arrange | positioned between the connection part J51 and the pressurization pump 5 in the supply water line L1. The second temperature sensor TE2 is connected to the permeate line L21 at the connection portion J31. The connection part J31 is arrange | positioned between the decarbonation apparatus 15 and the 1st flow-path switching valve V71 in the permeated water line L21. The third temperature sensor TE3 is connected to the demineralized water line L3 at the connection portion J43. The connection part J43 is arrange | positioned at the downstream demineralized water line L32 in the downstream from the 2nd flow-path switching valve V72 in the demineralized water line L3.

  The first temperature sensor TE1 to the third temperature sensor TE3 are electrically connected to the control unit 30. The temperature (detected water temperature value) of the supply water W1, the permeated water W2, or the desalted water W6 measured by the first temperature sensor TE1 to the third temperature sensor TE3 is transmitted to the control unit 30 as a detection signal.

  The first flow rate sensor FM1 and the second flow rate sensor FM2 are devices that measure the flow rate of water (permeated water W2 or desalted water W6) flowing through each connected line. The first flow rate sensor FM1 is connected to the permeate line L21 at the connection portion J10. The connection part J10 is arrange | positioned between the RO membrane module 7 and the decarbonation apparatus 15 in the permeated water line L21. The second flow rate sensor FM2 is connected to the demineralized water line L3 at the connection portion J38. The connection portion J38 is disposed between the EDI stack 16 and the second flow path switching valve V72 in the desalted water line L3.

  The first flow rate sensor FM1 and the second flow rate sensor FM2 are electrically connected to the control unit 30. The flow rate (detected flow rate value) of the permeated water W2 or the desalted water W6 measured by the first flow rate sensor FM1 and the second flow rate sensor FM2 is transmitted to the control unit 30 as a detection signal.

  The first electrical conductivity sensor EC1 is a device that measures the electrical conductivity (electrical characteristic value) of the permeated water W2 flowing through the permeated water line L21. The first electrical conductivity sensor EC1 is connected to the permeated water line L21 at the connection portion J32. The connection part J32 is arrange | positioned between the decarboxylation apparatus 15 and the 1st flow-path switching valve V71 in the permeated water line L21.

  1st specific resistance sensor RS1 and 2nd specific resistance sensor RS2 are apparatus which measures the specific resistance (electrical characteristic value) of the desalinated water W6 which distribute | circulates the desalted water line L8. 1st specific resistance sensor RS1 is connected to the desalted water line L3 in the connection part J37. The connection portion J37 is disposed between the EDI stack 16 and the second flow path switching valve V72 in the desalted water line L3. The second specific resistance sensor RS2 is connected to the demineralized water line L3 at the connection portion J41. The connection part J41 is arrange | positioned at the downstream demineralized water line L32 in the downstream from the 2nd flow-path switching valve V72 in the demineralized water line L3. Note that the first specific resistance sensor RS1 and the second specific resistance sensor RS2 incorporate a temperature sensor for temperature compensation of the measured specific resistance value. Therefore, the first specific resistance sensor RS1 and the second specific resistance sensor RS2 can measure the water temperature of the desalted water W6.

  The first electrical conductivity sensor EC1, the first specific resistance sensor RS1, and the second specific resistance sensor RS2 are electrically connected to the control unit 30. The electrical conductivity of the permeated water W2 measured by the first electrical conductivity sensor EC1, the specific resistance (and temperature) of the desalted water W6 measured by the first specific resistance sensor RS1, and the second specific resistance sensor RS2. The specific resistance (and temperature) of the desalted water W6 is transmitted to the control unit 30 as a detection signal.

  The second TOC sensor TOC2 is a device that detects the amount of organic carbon in the desalted water W6 flowing through the desalted water line L8. The second TOC sensor TOC2 has the same configuration as the first TOC sensor TOC1 described above. The description of the second TOC sensor TOC2 is applied to the description of the first TOC sensor TOC1, and the description thereof is omitted. The second TOC sensor TOC2 is connected to the demineralized water line L3 at the connection portion J42. The connection part J42 is arrange | positioned at the downstream demineralized water line L32 in the downstream from the 2nd flow-path switching valve V72 in the demineralized water line L3.

  The second TOC sensor TOC2 is electrically connected to the control unit 30. The total amount of organic carbon in the demineralized water W6 detected by the second TOC sensor TOC2 is transmitted to the control unit 30 as a detection signal.

  The input operation unit 40 is an input interface that receives an input operation of a user or an administrator for selection related to the operation mode of the device (for example, selection of operation / stop, release of alarm, etc.) and various settings related to the operation condition of the device. is there. The input operation unit 40 includes an operation panel that combines a display and button switches, a touch panel that directly operates on the display, and the like. The input operation unit 40 is electrically connected to the control unit 30. Information input from the input operation unit 40 is transmitted to the control unit 30.

  The display unit 60 displays desired information. The display unit 60 is electrically connected to the control unit 30.

  Next, the control unit 30 will be described. The control unit 30 is configured by a microprocessor (not shown) including a CPU and a memory. In the control unit 30, the CPU of the microprocessor executes various controls described later according to a predetermined program read from the memory. In the control unit 30, data and various programs for controlling the pure water production apparatus 1 are stored in the memory of the microprocessor. The microprocessor of the control unit 30 incorporates an integrated timer unit (hereinafter also referred to as “ITU”) that manages timekeeping and the like.

  As the flow rate feedback water amount control, the control unit 30 calculates the drive frequency of the pressurizing pump 5 by the speed type digital PID algorithm so that the detected flow rate value of the first flow rate sensor FM1 becomes a preset target flow rate value. Then, a current value signal (command signal) corresponding to the calculated value of the driving frequency is output to the inverter 6. The flow rate feedback water amount control by the control unit 30 will be described later.

  Moreover, the control part 30 performs the recovery rate control (henceforth "temperature feedforward recovery rate control") of the permeated water W2 based on the temperature of the supply water W1. This temperature feedforward recovery rate control is executed in parallel with the above-described flow rate feedback water amount control. The temperature feedforward recovery rate control by the control unit 30 will be described later.

  The control unit 30 sets the flow rate of the concentrated water W3 by controlling the valve opening degree of the proportional control valve V50 in order to set the circulation ratio R in the RO membrane module 7, and also controls the rotational speed of the pressurizing pump 5. To set the flow rate of the permeated water W2. The ratio of the flow rate of the concentrated water W3 to the flow rate of the permeated water W2 separated by the RO membrane module 7 is defined as a circulation ratio R in the RO membrane module 7. The control for setting the circulation ratio R in the RO membrane module 7 is executed in parallel with the above-described flow rate feedback water amount control and temperature feedforward recovery rate control.

  In accordance with the water quality detected by the turbidity sensor S3, the iron concentration sensor, or the first TOC sensor TOC1 (water quality detection means), the control unit 30 has a circulation ratio R in the RO membrane module 7 within a range of 2 ≦ R ≦ 10. So that the valve opening of the proportional control valve V50 is set so as to set the flow rate of the concentrated water W3, and the rotational speed of the pressurizing pump 5 is set so as to be within the predetermined circulation ratio R range. Is controlled so as to set the flow rate of the permeated water W2.

  The control unit 30 reduces the circulation ratio R when the water quality detected by the turbidity sensor S3, the iron concentration sensor or the first TOC sensor TOC1 is improved, or the turbidity sensor S3, the iron concentration sensor or the first TOC sensor. The opening degree of the proportional control valve V50 is controlled so as to set the flow rate of the concentrated water W3 so as to increase the circulation ratio R when the water quality detected by the TOC1 is lowered, and the rotational speed of the pressurizing pump 5 is increased. Is controlled so as to set the flow rate of the permeated water W2.

  Next, flow rate feedback water amount control by the control unit 30 will be described. FIG. 3 is a flowchart showing a processing procedure when the control unit 30 executes the flow rate feedback water amount control. The process of the flowchart shown in FIG. 3 is repeatedly executed during operation of the pure water production apparatus 1.

In step ST101 shown in FIG. 3, the control unit 30 acquires a target flow rate value Q _p ′ of the permeated water W2. This target flow rate value Q _p ′ is, for example, a set value that is input to the memory of the control unit 30 by the device administrator via the input operation unit 40.

  In step ST102, the control unit 30 determines whether or not the time t measured by the ITU has reached 100 ms, which is the control period (Δt). In step ST102, when the control unit 30 determines that the time t measured by the ITU has reached 100 ms (YES), the process proceeds to step ST103. In step ST102, when the control unit 30 determines that the time measured by the ITU has not reached 100 ms (NO), the process returns to step ST102.

Step ST 103: In (step ST 102 YES judgment), the control unit 30 acquires the detected flow rate value _{Q p} of the first flow rate sensor FM1 as a feedback value.

In step ST 104, the control unit 30 detects the flow rate value obtained in step ST 103 (feedback value) _{Q p} and, as difference between the target flow rate value _{Q p} 'obtained in step ST101 becomes zero, velocity type digital PID The operation amount _Un is calculated by an algorithm. In the speed type digital PID algorithm, the operation amount change ΔU _n is calculated every control cycle Δt (100 ms), and this is added to the operation amount U _n−1 at the previous control cycle, thereby obtaining the current operation amount U. _n is determined.

An arithmetic expression used for the velocity type digital PID algorithm is expressed by the following expressions (1a) and (1b).
_{ΔU n = K p {(e} n -e n-1) + (Δt / T i) × e n + (T d / Δt) × (e n -2e n-1 + e n-2)} (1a)
U _n = U _n-1 + ΔU _n (1b)

In Expression (1a) and Expression (1b), Δt: control period, U _n : current operation amount, U _n-1 : operation amount at the previous control period, ΔU _n : change in operation amount from the previous time to this time. Minute, e _n : magnitude of current deviation, e _n-1 : magnitude of deviation at the previous control cycle, e _n-2 : magnitude of deviation at the previous control cycle, K _p : proportional gain, T _i : integration time, T _d : differentiation time. The size e _n of the current deviation is obtained by the following formula (2).
e _n = Q _p ′ −Q _p (2)

In step ST105, the control unit 30 uses the current operation amount U _n , the target flow rate value Q _p ′, and the maximum drive frequency of the pressurizing pump 5 (set value of 50 Hz or 60 Hz) according to a predetermined arithmetic expression, The drive frequency F [Hz] of the pressure pump 5 is calculated.

  In step ST <b> 106, the control unit 30 converts the calculated value of the drive frequency F into a corresponding current value signal (command signal: 4 to 20 mA), and outputs this current value signal to the inverter 6. Thereby, the process of this flowchart is complete | finished (it returns to step ST101). In step ST106, when the control unit 30 outputs a current value signal to the inverter 6, the inverter 6 supplies the driving power converted to the frequency specified by the input current value signal to the pressurizing pump 5. As a result, the pressurization pump 5 is driven at a rotational speed corresponding to the drive frequency input from the inverter 6.

  Next, temperature feedforward recovery rate control by the control unit 30 will be described. FIG. 4 is a flowchart showing a processing procedure when the control unit 30 executes the temperature feedforward recovery rate control. The process of the flowchart shown in FIG. 4 is repeatedly executed during the operation of the pure water production apparatus 1.

In step ST201 shown in FIG. 4, the control unit 30 acquires a target flow rate value Q _p ′ of the permeated water W2. This target flow rate value Q _p ′ is, for example, a set value that is input to the memory by the device administrator via the input operation unit 40.

In step ST202, the control unit 30 acquires the silica (SiO ₂ ) concentration C _s of the supply water W1. The silica concentration C _s is a set value that is input to the memory by the apparatus administrator via a user interface (not shown), for example. The silica concentration of the supply water W1 can be obtained by analyzing the water quality of the supply water W1 in advance. In the supply water line L1, the silica concentration of the supply water W1 may be measured by a water quality sensor (not shown).

  In step ST203, the control unit 30 acquires the detected temperature value T of the supply water W1 from the first temperature sensor TE1.

In step ST204, the control unit 30 determines silica solubility S _s with respect to water based on the acquired detected temperature value T.

In step ST205, the control unit 30 calculates the allowable concentration magnification N _s of silica in the concentrated water W3 based on the silica concentration C _s acquired or determined in the previous step and the silica solubility S _s . Permissible concentration rate N _s of silica can be obtained by the following equation (3).
N _s = S _s / C _s (3)

In step ST 206, the control unit 30, prior to the target flow rate value Q _p acquired or calculated in step _', and based on the allowable concentration rate N _s, wastewater flow rate recovery is maximized (target drainage flow Q _d') Is calculated. The target drainage flow rate Q _d ′ can be obtained by the following equation (4).
Q _d ′ = Q _p ′ / (N _s −1) (4)

In step ST207, the control unit 30, the actual drainage flow _{Q d} is the target wastewater flow rate _{Q d} 'and so as to control the opening speed of the first drain valve V32~ third drain valve V34 calculated in step ST206 concentrated water W3 To do. Thereby, the process of this flowchart is complete | finished (it returns to step ST201). In the pure water manufacturing apparatus 1 according to the first embodiment, the control unit 30 performs temperature feedforward recovery rate control. For this reason, in the pure water manufacturing apparatus 1, precipitation of the silica scale in the RO membrane module 7 can be suppressed more reliably while maximizing the recovery rate of the permeated water W2.

  Next, a process for increasing / decreasing the circulation ratio R by the control unit 30 will be described. FIG. 5 is a flowchart showing a processing procedure for increasing or decreasing the circulation ratio in the control unit 30. The process of the flowchart shown in FIG. 5 is repeatedly executed during the operation of the pure water production apparatus 1.

  In step ST301, the control unit 30 controls the valve opening degree of the proportional control valve V50 so as to set the flow rate of the concentrated water W3 so that the circulation ratio R in the RO membrane module 7 is 5, and pressurizes. The rotational speed of the pump 5 is controlled so as to set the flow rate of the permeated water W2.

  In step ST302, the control unit 30 acquires the measured turbidity of the supply water W1 measured by the turbidity sensor S3.

  In step ST303, the control unit 30 acquires the measured iron concentration of the supply water W1 measured by the iron concentration sensor S4.

  In step ST304, the control unit 30 acquires the measured TOC value of the supply water W1 measured by the first TOC sensor TOC1.

  In step ST305, the control unit 30 determines whether or not the measured turbidity of the supply water W1 measured by the turbidity sensor S3 exceeds a predetermined turbidity threshold value. If it is determined that the measured turbidity of the feed water W1 measured by the turbidity sensor S3 exceeds a predetermined turbidity threshold (YES), the process proceeds to step ST308. When it is determined that the measured turbidity of the feed water W1 measured by the turbidity sensor S3 is below a predetermined turbidity threshold (NO), the process proceeds to step ST306.

  In step ST308, the control unit 30 controls the valve opening degree of the proportional control valve V50 so as to increase the circulation ratio R so as to set the flow rate of the concentrated water W3, and the rotational speed of the pressurizing pump 5 is set as follows. Control is performed so as to set the flow rate of the permeated water W2. Specifically, in order to increase (increase) the circulation ratio R, for example, the control unit 30 controls the valve opening of the proportional control valve V50 so as to maintain the flow rate of the concentrated water W3 and the permeated water W2. The target flow rate of the permeated water W2 is maintained while the valve opening degree of the proportional control valve V50 is controlled so as to increase the flow rate of the concentrated water W3. The pressure pump 5 is controlled. By increasing the circulation ratio R in the RO membrane module 7, turbulence can be promoted on the primary surface of the RO membrane. Thereby, when the water quality of the supply water W1 is poor, by increasing the circulation ratio R in the RO membrane module 7, fouling on the surface of the RO membrane is suppressed, and membrane clogging of the RO membrane is less likely to occur.

  In step ST306, the control unit 30 determines whether or not the measured iron concentration of the supply water W1 measured by the iron concentration sensor S4 exceeds a predetermined iron concentration threshold. When it is determined that the measured iron concentration of the supply water W1 measured by the iron concentration sensor S4 exceeds the predetermined iron concentration threshold (YSE), the process proceeds to step ST308. When it is determined that the measured iron concentration of the supply water W1 measured by the iron concentration sensor S4 is lower than the predetermined iron concentration threshold (NO), the process proceeds to step ST307.

  In step ST307, the control unit 30 determines whether or not the measured TOC value of the supply water W1 measured by the first TOC sensor TOC1 exceeds a predetermined TOC threshold value. If it is determined that the measured TOC value of the feed water W1 measured by the first TOC sensor TOC1 exceeds the predetermined TOC threshold (YSE), the process proceeds to step ST308. When it is determined that the measured TOC value of the supply water W1 measured by the first TOC sensor TOC1 is lower than the predetermined TOC threshold (NO), the process proceeds to step ST309.

In step ST309, the control unit 30 controls the valve opening of the proportional control valve V50 so as to lower the circulation ratio R so as to set the flow rate of the concentrated water W3, and the rotational speed of the pressurizing pump 5 is set as follows. Control is performed so as to set the flow rate of the permeated water W2. Specifically, in order to decrease (lower) the circulation ratio R, for example, the control unit 30 controls the valve opening degree of the proportional control valve V50 so as to maintain the flow rate of the concentrated water W3 and the permeated water W2. The target flow rate of the permeated water W2 is maintained while the valve opening degree of the proportional control valve V50 is controlled so as to decrease the flow rate of the concentrated water W3. The pressure pump 5 is controlled. Thereby, when the water quality of the supply water W1 is good, the power consumption can be suppressed in the operation of the pressurization pump 5 by lowering the circulation ratio R in the RO membrane module 7.
After step ST309, the process of this flowchart ends (returns to step ST301).

  According to the pure water manufacturing apparatus 1 which concerns on 1st Embodiment mentioned above, the following effects are show | played, for example.

  In the first embodiment, according to the water quality detected by the water quality detection means (turbidity sensor S3, iron concentration sensor S4, first TOC sensor TOC1), the circulation ratio R in the RO membrane module 7 has a predetermined circulation ratio. At least one of the flow rate of the supply water W1, the flow rate of the permeate water W2, and the flow rate of the concentrated water W3 is set so as to be within the range (circulation ratio R is within the range of 2 to 10). Therefore, when the quality of the supply water W1 is good, the circulation ratio R can be set small in order to suppress power consumption in the operation of the pressurizing pump 5. In addition, when the quality of the supply water W1 is poor, the circulation ratio R can be set large in order to suppress membrane clogging on the surface of the RO membrane. Thereby, while suppressing power consumption in the operation of the pressurizing pump 5, fouling on the surface of the RO membrane in the RO membrane module 7 is suppressed, and membrane clogging of the RO membrane is less likely to occur.

  In the first embodiment, when the water quality detected by the water quality detection means (turbidity sensor S3, iron concentration sensor S4, first TOC sensor TOC1) is improved, the circulation ratio R is decreased, or the water quality detection is performed. When the water quality detected by the means (turbidity sensor S3, iron concentration sensor S4, first TOC sensor TOC1) is lowered, the flow rate of the supply water W1, the flow rate of the permeated water W2, and the concentrated water so as to increase the circulation ratio R. At least one of the flow rates of W3 is set. Therefore, when the water quality detected by the water quality detection means (turbidity sensor S3, iron concentration sensor S4, first TOC sensor TOC1) is improved, the power consumption of the pressure pump 5 is suppressed by lowering the circulation ratio R. be able to. Further, when the water quality detected by the water quality detection means (turbidity sensor S3, iron concentration sensor S4, first TOC sensor TOC1) is reduced, the circulation ratio R is increased to increase the RO membrane surface in the RO membrane module 7. Fouling is suppressed and RO membrane clogging is less likely to occur. Therefore, by increasing or decreasing the circulation ratio R in the RO membrane module 7, when the water quality of the supply water W1 is good, priority can be given to suppression of power consumption in the operation of the pressurizing pump 5, and the supply water W1. When the water quality is poor, priority can be given to suppression of membrane clogging on the surface of the RO membrane.

(Second Embodiment)
Next, a pure water producing apparatus 1A according to a second embodiment of the present invention will be described with reference to FIGS. 6 and 7A to 7C. FIG. 6 is an overall schematic diagram of a pure water producing apparatus 1A according to the second embodiment. FIG. 7A is a first middle portion of the entire configuration diagram of the pure water producing apparatus 1A according to the second embodiment. FIG. 7B is a second middle part of the overall configuration diagram of the pure water producing apparatus 1A according to the second embodiment. FIG. 7C is a rear part of the entire configuration diagram of the pure water producing apparatus 1A according to the second embodiment.

  In the second embodiment, differences from the first embodiment will be mainly described. For this reason, the same code | symbol is attached | subjected about the same (or equivalent) structure as 1st Embodiment, and detailed description is abbreviate | omitted. The description of the first embodiment is appropriately applied to points that are not particularly described in the second embodiment. Moreover, in 2nd Embodiment, the structure from the upstream of the supply water line L1 to the supply water replenishment valve V31 is the same as that of 1st Embodiment. Therefore, in 2nd Embodiment, main drawings (drawing corresponding to FIG. 2A) about the structure from the upstream of the supply water line L1 in 1st Embodiment to the supply water replenishment valve V31 and its description are abbreviate | omitted.

  The pure water producing apparatus 1A according to the second embodiment is a two-stage RO membrane arranged in series, whereas the pure water producing apparatus 1 in the first embodiment includes the one-stage RO membrane module 7. The pure water production apparatus 1 according to the first embodiment is provided in that the modules 10 and 14 are provided, the intermediate tank 11 is provided between the two-stage RO membrane modules 10 and 14, and the configuration around these. And mainly different.

  In the second embodiment, the “RO membrane module 7” in the first embodiment is referred to as the “first-stage RO membrane module 10” as the first-stage RO membrane module in the second embodiment, and further the second-stage RO membrane module. As the membrane module, a “rear-stage RO membrane module 14” is provided. Therefore, in the second embodiment, the “permeate water line L21” in the first embodiment is referred to as a “front-stage RO permeate line L22”, and the permeate separated by the front-stage RO membrane module 10 is referred to as a “front-stage permeate water W2”. .

  In the second embodiment, the “RO permeate return line L41” in the first embodiment is referred to as the “front-stage RO permeate return line L43”, and the “RO concentrated water return line L51” in the first embodiment is referred to as the “front-stage RO. Concentrated water return line L53 ". Further, in the second embodiment, the “pressurizing pump 5” in the first embodiment is referred to as “pre-stage pressurizing pump 8”, and “inverter 6” is referred to as “pre-stage inverter 9”.

  As shown in FIG. 6, the pure water producing apparatus 1A according to the second embodiment includes a first optional device OP1, a prefilter 4, a second optional device OP2, a pre-stage pressurizing pump 8, and a pre-stage inverter 9. The upstream RO membrane module 10, the intermediate tank 11, the downstream pressure pump 12, the downstream inverter 13, the downstream RO membrane module 14, the third optional device OP3, the first flow path switching valve V71, and the EDI stack 16, a second flow path switching valve V <b> 72, a fourth optional device OP <b> 4, a control unit 30 </ b> A, an input operation unit 40, a DC power supply device 50, and a display unit 60.

  Moreover, as shown in FIG. 6, the pure water manufacturing apparatus 1A of the second embodiment includes a supply water line L1, a front-stage RO permeate line L22, a front-stage RO permeate return line L43, and a front-stage RO concentrated water return line. L53, the back | latter stage RO permeated water line L23, the back | latter stage RO permeated water return line L44, the front | former stage RO concentrated water return line L54, the desalted water line L3, and the desalted water return line L45 are provided.

  As shown in FIG. 6, the pure water producing apparatus 1A according to the second embodiment replaces the RO permeate return line L41 and the desalted water return line L42 according to the first embodiment with a front-stage RO permeate return line L43 and a rear-stage RO. A permeated water return line L44 and a desalted water return line L45 are provided.

  Moreover, as shown to FIG. 7A-FIG. 7C, the pure water manufacturing apparatus 1A of 2nd Embodiment is not provided with 2nd pressure sensor PS2 in 1st Embodiment, On the other hand, 5th pressure sensor PS5, 4th A temperature sensor TE4, a fifth temperature sensor TE5, a third flow rate sensor FM3, and a second electrical conductivity sensor EC2 are further provided. Similarly to the first embodiment, the pure water manufacturing apparatus 1A of the second embodiment includes the first electrical conductivity sensor EC1 and the first specific resistance sensor RS1.

  The pre-stage RO membrane module 10 separates the supply water W1 pumped by the pre-stage pressurization pump 8 into a pre-stage permeate water W2 from which dissolved salts have been removed and a concentrated water W3 from which dissolved salts have been concentrated.

  The front-stage RO permeate line L22 is a line through which the front-stage permeate water W2 separated by the front-stage RO membrane module 10 flows to the rear-stage RO membrane module 14. The upstream end of the upstream RO permeate line L22 is connected to the secondary port of the upstream RO membrane module 10 (the outlet of the upstream permeate W2), as shown in FIG. 7A. As shown in FIG. 7B, the downstream end of the upstream RO permeate line L22 is connected to the primary inlet port (the inlet of the upstream permeate W2) of the downstream RO membrane module 14.

  As shown in FIG. 7A, the upstream RO permeated water line L22 is connected to the connecting portion J54, the upstream permeated water replenishing valve V35, the third check valve V63, the connecting portion J10, the connecting portion J12, and the connecting portion J13. , And a sixth on-off valve V16. Further, after the sixth on-off valve V16, as shown in FIG. 7B, the intermediate tank 11, the seventh on-off valve V17, the connection portion J61, the connection portion J21, the post-stage pressurizing pump 12, the connection portion J22, and the post-stage RO membrane A module 14 is provided. As shown in FIG. 7A, the upstream end of the upstream RO permeate return line L43 is connected to the connecting portion J54. Moreover, as shown to FIG. 7B, the downstream end part of the back | latter stage RO concentrated water return line L54 is connected to the connection part J61.

  The front-stage permeated water supply valve V35 is an automatic valve that can control the opening and closing of the front-stage RO permeated water line L22. The front stage permeated water replenishment valve V35 is electrically connected to the control unit 30A. The opening and closing of the front permeate replenishment valve V35 is controlled by a flow path opening / closing signal transmitted from the control unit 30A.

  As shown in FIG. 6, the intermediate tank 11 is provided between the front RO membrane module 10 and the rear RO membrane module 14 in the front RO permeate line L22. The intermediate tank 11 is a tank that stores the previous-stage permeated water W <b> 2 separated by the previous-stage RO membrane module 10.

  The intermediate tank 11 is provided with a water level sensor 111 as shown in FIG. 7B. The water level sensor 111 is a device that detects the water level of the upstream permeated water W2 stored in the intermediate tank 11. The water level sensor 111 is electrically connected to the control unit 30A. The water level (hereinafter also referred to as “detected water level value”) of the intermediate tank 11 measured by the water level sensor 111 is transmitted as a detection signal to the control unit 30A.

  In the present embodiment, the water level sensor 111 is, for example, a level switch. The level switch is a preset liquid level position detector, and is configured to detect, for example, a plurality of liquid level positions (for example, 4 positions). FIG. 7B shows an example in which a float type level switch is provided as the water level sensor 111. The water level sensor 111 is not limited to a level switch, and may be a continuous level sensor, for example. As the continuous level sensor, for example, a capacitive sensor, a pressure sensor, an ultrasonic sensor, or the like is used.

  The post-stage pressurizing pump 12 is a device that sucks the pre-stage permeate water W2 flowing through the pre-stage RO permeate line L22 and pumps it toward the post-stage RO membrane module 14. The post-stage pressurizing pump 12 is supplied with drive power having a frequency converted from the post-stage inverter 13. The post-stage pressurizing pump 12 is driven at a rotational speed corresponding to the frequency of the supplied driving power (hereinafter also referred to as “driving frequency”).

  The rear-stage inverter 13 is an electric circuit (or a device having the circuit) that supplies driving power whose frequency is converted to the rear-stage pressurization pump 12. The rear stage inverter 13 is electrically connected to the control unit 30A. A command signal is input to the subsequent inverter 13 from the control unit 30A. The rear stage inverter 13 outputs driving power having a driving frequency corresponding to the command signal (current value signal or voltage value signal) input by the control unit 30 </ b> A to the rear stage pressure pump 12.

  The latter-stage RO membrane module 14 is separated from the first-stage permeate W2 separated from the first-stage RO membrane module 10 and pumped by the second-stage pressurization pump 12, with the second-stage permeate W4 from which dissolved salts are removed from the first-stage permeate W2. Separated into concentrated water W5 enriched with salts. The post-stage RO membrane module 14 is configured by accommodating a single or a plurality of spiral RO membrane elements in a pressure vessel (vessel).

  The front-stage RO permeate return line L43 is a line that returns the front-stage permeate W2 separated by the front-stage RO membrane module 10 to the supply water line L1 upstream of the front-stage RO membrane module 10 as shown in FIG. 7A. . The upstream end of the upstream RO permeate return line L43 is connected to the connection J54. The downstream end of the upstream RO permeated water return line L43 is connected to the upstream RO concentrated water return line L53 at the connection portion J52. The connection part J52 is disposed between the connection part J53 and the connection part J51 in the upstream RO concentrated water return line L53. The part from the connection part J52 to the connection part J51 in the upstream RO permeate return line L43 is common to the part from the connection part J52 to the connection part J51 in the upstream RO concentrated water return line L53.

  As shown in FIG. 7A, a relief valve V43 is provided in the upstream RO permeate return line L43. The relief valve V43 is a normally closed pressure operating valve, and is an adjustment valve that is opened when the pressure on the primary side is higher than the pressure on the secondary side by a certain pressure or more. Specifically, the relief valve V43 is opened when the pipe pressure of the front-stage RO permeate return line L43 becomes equal to or higher than a preset pressure, and the front-stage permeate W2 flowing through the front-stage RO permeate line L22 is removed. This is a valve for flowing through the connecting portion J54 to the upstream RO permeated water return line L43.

  The pressure on the secondary side of the relief valve V43 (the pressure of the supply water W1 at the connection portion J51) is adjusted to be less than the operating pressure of the upstream pressurizing pump 8 by the pressure reducing valve V42. When the front-stage pressurizing pump 8 is driven in a state in which the front-stage permeate replenishment valve V35 is controlled to be closed, the primary pressure in the relief valve V43 (the pressure of the front-stage permeate W2 at the connection portion J54) is secondary. Higher than the pressure on the side. Thereby, the relief valve V43 is opened, and the front-stage permeate water W2 flowing through the front-stage RO permeate water line L22 can be circulated to the front-stage RO permeate return line L43.

  As shown in FIG. 7B, the rear-stage RO concentrated water return line L54 is a line that returns a part W51 of the concentrated water W5 separated by the rear-stage RO membrane module 14 to the front-stage RO permeate water line L22. The upstream end of the rear-stage RO concentrated water return line L54 is connected to the primary-side outlet port (concentrated water outlet) of the rear-stage RO membrane module 14. The downstream end of the rear stage RO concentrated water return line L54 is connected to the connecting portion J61. The connecting portion J61 is disposed between the intermediate tank 11 and the post-stage pressurizing pump 12 in the pre-stage RO permeate line L22.

  As shown in FIG. 7B, the rear stage RO concentrated water return line L54 is provided with a connecting portion J63, a connecting portion J62, a sixth check valve V66, a sixth constant flow valve V56, and a connecting portion J61 in this order from the upstream side. ing. The upstream end of the first second-stage RO concentrated water line L63 is connected to the connecting portion J62. The upstream end of the second second-stage RO concentrated water line L64 is connected to the connecting portion J63.

  The first second-stage RO concentrated water line L63 and the second second-stage RO concentrated water line L64 remove the remaining portion W52 of the concentrated water W5 separated by the second-stage RO membrane module 14 from the middle of the second-stage RO concentrated water return line L54. Is a line to send to The downstream end of the first second-stage RO concentrated water line L63 and the downstream end of the second second-stage RO concentrated water line L64 are connected to the upstream end of the second-stage RO concentrated water delivery line L65 at the connection J64. It is connected. The downstream end of the downstream RO concentrated water delivery line L65 is connected to the decarboxylation device 15 as shown in FIG. 7C. The first second-stage RO concentrated water line L63 and the second second-stage RO concentrated water line L64 are provided with a first regulating valve V36 and a second regulating valve V37, and a seventh constant flow valve V57 and an eighth constant flow valve V58, respectively. It has been.

  The first adjusting valve V36 and the second adjusting valve V37 can adjust the delivery flow rate of the concentrated water W5 by individually opening and closing the first second-stage RO concentrated water line L63 and the second second-stage RO concentrated water line L64. . The first regulating valve V36 and the second regulating valve V37 are each electrically connected to the control unit 30A. Opening and closing of the first regulating valve V36 and the second regulating valve V37 is controlled by a drive signal transmitted from the control unit 30A.

  An eighth open / close valve V18 is provided in the downstream RO concentrated water delivery line L65. The eighth on-off valve V18 is a manual valve that can be operated to open and close the rear-stage RO concentrated water delivery line L65.

  The post-stage RO permeate water line L23 is a line through which the post-stage permeate water W4 separated by the post-stage RO membrane module 14 flows through the EDI stack 16. As shown in FIG. 7B, the upstream end of the rear-stage RO permeate line L23 is connected to the secondary port of the rear-stage RO membrane module 14 (the outlet of the rear-stage permeate water W4). As shown in FIG. 7C, the downstream end of the downstream RO permeate line L23 is connected to the EDI stack 16 via the first flow path switching valve V71.

  The rear-stage RO permeate line L23 includes a front-stage permeate line L231, a middle-stage permeate line L232, a desalting chamber inflow line L233, and a concentration chamber inflow line L234. As shown in FIG. 7B, the upstream side permeated water line L231 is provided with a fourth check valve V64, a connecting portion J23, and a ninth on-off valve V19 in order from the upstream side. Further, after the ninth on-off valve V19, as shown in FIG. 7C, a decarboxylation device 15, a connection portion J31, a connection portion J32, and a first flow path switching valve V71 are provided.

  The first flow path switching valve V71 is a flow path (water sampling side flow path) for allowing the downstream permeate water W4 separated by the rear RO membrane module 14 to flow toward the EDI stack 16 via the middle permeate water line L232. Alternatively, it is a valve that can be switched to a flow path (circulation side flow path) that circulates toward the intermediate tank 11 via the rear-stage RO permeate return line L44. The first flow path switching valve V71 is configured by, for example, an electric or electromagnetic three-way valve. The first flow path switching valve V71 is electrically connected to the control unit 30A. The switching of the flow path in the first flow path switching valve V71 is controlled by a flow path switching signal transmitted from the control unit 30A.

  The post-stage RO permeate return line L44 is a line for returning the post-stage permeate water W4 separated by the post-stage RO membrane module 14 to the intermediate tank 11 provided between the pre-stage RO membrane module 10 and the post-stage RO membrane module 14. is there. As shown in FIG. 7C, the upstream end of the rear stage RO permeate return line L44 is connected to the first flow path switching valve V71. The downstream side of the rear stage RO permeate return line L44 is connected to the intermediate tank 11 as shown in FIG. 7B.

  In addition, in 2nd Embodiment shown to FIG. 7C, the structure of the part downstream from 1st flow-path switching valve V71 is "the middle stage permeate water line L212" in 1st Embodiment, and "desalination room inflow line L213." ”,“ Concentration chamber inflow line L214 ”and“ permeate water W2 ”, respectively,“ middle stage permeate water line L232 ”,“ desalination chamber inflow line L233 ”,“ concentration chamber inflow line L234 ”and“ rear stage permeate water W4 ”. " Moreover, in 2nd Embodiment, it is the structure similar to 1st Embodiment except the structure of the EDI concentrated water discharge line L72 and the desalted water return line L45 which are mentioned later. Therefore, regarding these parts, description of 1st Embodiment is used and description of 2nd Embodiment is abbreviate | omitted.

  As shown in FIG. 7C, the pure water producing apparatus 1A in the second embodiment includes an EDI concentrated water discharge line L72 instead of the EDI concentrated water line L52 in the first embodiment.

  The EDI concentrated water discharge line L72 is a line for discharging the concentrated water W7 discharged from the concentration chamber 162 of the EDI stack 16 to the outside of the apparatus. The upstream end of the EDI concentrated water discharge line L72 is connected to the secondary port of the EDI stack 16 (the outlet side of the concentration chamber 162). The downstream side of the EDI concentrated water discharge line L72 is connected or opened to a drain pit (not shown), for example.

  The second flow path switching valve V72 is a flow path (water sampling side flow path) for sending the desalted water W6 obtained in the desalination chamber 161 of the EDI stack 16 toward the demand point via the downstream side desalted water line L32. Or a valve that can be switched to a flow path (circulation side flow path) that circulates toward the intermediate tank 11 via the desalted water return line L45.

  The desalted water return line L45 is provided between the front-stage RO membrane module 10 and the rear-stage RO membrane module 14 with the desalted water W6 obtained in the desalination chamber 161 of the EDI stack 16 in the middle of the desalted water line L3. This is a line that returns to the intermediate tank 11. In the present embodiment, the upstream end of the desalted water return line L45 is connected to the second flow path switching valve V72. The downstream end of the desalted water return line L45 is connected to the intermediate tank 11.

  The fifth pressure sensor PS5 is a device that measures the pressure of the front-stage permeate water W2 that flows through the front-stage RO permeate line L22. The fifth pressure sensor PS5 is connected to the upstream RO permeated water line L22 at the connection portion J22. The connecting portion J22 is disposed between the rear-stage pressurizing pump 12 and the rear-stage RO membrane module 14 in the front-stage RO permeate water line L22. The fifth pressure sensor PS5 is electrically connected to the control unit 30A. The pressure of the pre-stage permeated water W2 measured by the fifth pressure sensor PS5 is transmitted as a detection signal to the control unit 30A.

  The fourth temperature sensor TE4 and the fifth temperature sensor TE5 are devices that measure the temperature of the front-stage permeate water W2 that flows through the front-stage RO permeate line L22. As shown in FIG. 7A, the fourth temperature sensor TE4 is connected to the upstream RO permeate line L22 at the connection portion J12. The connecting portion J12 is disposed between the upstream RO membrane module 10 and the intermediate tank 11 in the upstream RO permeate line L22. As shown in FIG. 7B, the fifth temperature sensor TE5 is connected to the upstream RO permeate line L22 at the connection portion J21. The connecting portion J21 is disposed between the intermediate tank 11 and the post-stage pressurizing pump 12 in the pre-stage RO permeate line L22. The fourth temperature sensor TE4 and the fifth temperature sensor TE5 are electrically connected to the control unit 30A. The temperature of the pre-stage permeate water W2 measured by the fourth temperature sensor TE4 and the fourth temperature sensor TE4 is transmitted as a detection signal to the control unit 30A.

  The third flow rate sensor FM3 is a device that measures the flow rate of the rear permeate water W4 that flows through the rear RO permeate line L23. As shown in FIG. 7B, the third flow rate sensor FM3 is connected to the rear-stage RO permeate line L23 at the connection portion J23. The connecting portion J23 is disposed between the rear-stage RO membrane module 14 and the decarboxylation device 15 in the rear-stage RO permeate line L23. The third flow rate sensor FM3 is electrically connected to the control unit 30A. The flow rate of the rear permeate water W4 measured by the third flow rate sensor FM3 is transmitted as a detection signal to the control unit 30A.

  The second electrical conductivity sensor EC2 is a device that measures the electrical conductivity of the front-stage permeate water W2 that flows through the front-stage RO permeate line L22. As shown in FIG. 7A, the second electrical conductivity sensor EC2 is connected to the upstream RO permeate line L22 at the connection portion J13. The connecting portion J13 is disposed between the upstream RO membrane module 10 and the intermediate tank 11 in the upstream RO permeate line L22. The second electrical conductivity sensor EC2 is electrically connected to the control unit 30A. The electrical conductivity of the upstream permeated water W2 measured by the second electrical conductivity sensor EC2 is transmitted as a detection signal to the control unit 30A.

  Next, the control unit 30A of the pure water manufacturing apparatus 1A according to the second embodiment will be described. In the second embodiment, the flow rate feedback water amount control and the temperature feedforward recovery rate control are executed on the upstream RO membrane module 10 and the downstream RO membrane module 14 in the control unit 30A. In the second embodiment, the control for setting or changing the circulation ratio R in the control unit 30 </ b> A is performed on the upstream RO membrane module 10.

  As the flow rate feedback water amount control for the upstream RO membrane module 10, the control unit 30A uses a speed type digital PID algorithm so that the detected flow rate value of the first flow sensor FM1 becomes a preset target flow rate value. 8 is calculated, and a current value signal (command signal) corresponding to the calculated value of the drive frequency is output to the pre-stage inverter 9.

  In addition, the control unit 30A uses the velocity type digital PID algorithm as a flow rate feedback water amount control for the downstream RO membrane module 14 so that the detected flow rate value of the third flow rate sensor FM3 becomes a preset target flow rate value. The drive frequency of the pressure pump 12 is calculated, and a current value signal (command signal) corresponding to the calculated value of the drive frequency is output to the subsequent inverter 13.

  The control unit 30A performs the recovery rate control of the upstream permeated water W2 (hereinafter also referred to as “temperature feedforward recovery rate control”) based on the temperature of the supply water W1. This temperature feedforward recovery rate control is executed in parallel with the above-described flow rate feedback water amount control.

  The control unit 30A determines that the circulation ratio R in the upstream RO membrane module 10 is the circulation in the upstream RO membrane module 10 according to the water quality detected by the turbidity sensor S3, the iron concentration sensor, or the first TOC sensor TOC1 (water quality detection means). The valve opening degree of the proportional control valve V50 and the flow rate of the concentrated water W3 are set so that the ratio R falls within the range of 2 ≦ R ≦ 10 (so as to fall within the predetermined circulation ratio R). While controlling, the rotational speed of the pre-stage pressurizing pump 8 is controlled so as to set the flow rate of the pre-stage permeate W2.

  The control unit 30A reduces the circulation ratio R when the water quality detected by the turbidity sensor S3, the iron concentration sensor or the first TOC sensor TOC1 is improved, or the turbidity sensor S3, the iron concentration sensor or the first TOC sensor. The valve opening degree of the proportional control valve V50 is controlled so as to set the flow rate of the concentrated water W3 so as to increase the circulation ratio R when the water quality detected by the TOC1 is lowered. The speed is controlled so as to set the flow rate of the upstream permeated water W2.

  The other points of the flow rate feedback water amount control and the temperature feedforward recovery rate control in the second embodiment are the same as the flow rate feedback water amount control and the temperature feedforward recovery rate control in the first embodiment. Therefore, the description of the flow rate feedback water amount control and the temperature feedforward recovery rate control in the second embodiment uses the description of the flow rate feedback water amount control and the temperature feedforward recovery rate control in the first embodiment, and omits the description. . The other controls in the second embodiment are substantially the same as the controls in the first embodiment.

  According to 1A of the pure water manufacturing apparatuses which concern on 2nd Embodiment mentioned above, there exists an effect similar to the pure water manufacturing apparatus 1 which concerns on the above-mentioned 1st Embodiment.

The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and can be implemented in various forms.
For example, in the first and second embodiments, the water quality detection means (turbidity sensor S3, iron concentration sensor or first TOC sensor TOC1) is configured to detect the water quality of the supply water W1. In the first and second embodiments, the concentrated water W3 is mixed with the supply water W1 via the RO concentrated water return line L51 on the premise of a cross flow configuration. Therefore, in the case where the concentrated water W3 is mixed with the supply water W1 via the RO concentrated water return line L51 by cross flow, the supply water W1 includes the supply water W1 (raw water) before mixing the concentrated water W3. And supply water W1 (raw water + concentrated water W3) after mixing of the concentrated water W3. Therefore, the water quality detection means may be configured to detect either the supply water W1 before mixing the concentrated water W3 or the supply water W1 after mixing the concentrated water W3. The raw water includes soft water produced by the water softener 2 and treated water treated by a pretreatment device such as the filtration treatment device 3.

  In the first and second embodiments, the water quality detection means (turbidity sensor S3, iron concentration sensor or first TOC sensor TOC1) is configured to detect the water quality of the supply water W1, but is not limited thereto. Instead, the water quality of the concentrated water W3 may be detected. In this case, according to the water quality of the concentrated water W3 detected by the water quality detection means, the flow rate of the supply water W1 and the flow rate of the permeated water W2 so that the circulation ratio R falls within the range of the predetermined circulation ratio R. And at least one of the flow rates of the concentrated water W3 is set.

  In the first and second embodiments, the turbidity sensor S3, the iron concentration sensor S4, and the first TOC sensor TOC1 are provided as the water quality detection means. However, not all sensors need to be provided. Any one or more of the sensor S3, the iron concentration sensor S4, and the first TOC sensor TOC1 may be provided.

  In the first and second embodiments, a non-regenerative mixed bed ion exchange column may be provided in place of the EDI stack (electric deionization stack) 16. In this case, deionized water can be obtained by deionizing the permeated water separated by the preceding RO membrane module with the ion exchange resin bed. In addition, immediately after the start of operation of the apparatus, deionized water whose water quality has been recovered can be supplied to the demand point. Further, by using the ion exchange tower, the power required for the treatment for obtaining deionized water from the permeated water can be made substantially zero.

  In the first and second embodiments, the control unit 30 controls the flow rate of the permeated water W2 and the flow rate of the concentrated water W3 when adjusting the circulation ratio R, but is not limited thereto. When adjusting the circulation ratio R, the control unit 30 may perform control so that at least one of the flow rate of the supply water W1, the flow rate of the permeated water W2, and the flow rate of the concentrated water W3 is set.

  1st and 2nd embodiment demonstrated the example which adjusts the waste_water | drain flow volume of the concentrated water W3 in steps by selecting the open | release number of the 1st drain valve V32-the 3rd drain valve V34. For example, the RO concentrated water discharge line L61 may be provided with a proportional control valve without branching the RO concentrated water discharge line L61. In this case, the flow rate of the concentrated water W3 can be adjusted by transmitting a current value signal from the control unit (30, 30A) to the proportional control valve to control the valve opening.

  Moreover, in the structure which provided the proportional control valve in RO concentrated water discharge line L61, it is good also as a structure which provided the flow sensor in RO concentrated water discharge line L61. In this case, the actual drainage flow rate of the concentrated water W3 can be more accurately controlled by inputting the flow rate value measured by the flow rate sensor to the control unit (30, 30A) as a feedback value.

  Further, in the configuration in which the proportional control valve V50 is provided in the RO concentrated water return line L51, not the configuration in which the valve opening degree of the proportional control valve V50 is controlled, but a plurality of on-off valves are provided in parallel with the RO concentrated water return line L51. The flow rate of the concentrated water W3 may be adjustable. In this case, the circulation ratio R of the RO membrane module 7 can be adjusted by adjusting the concentrated water W3 flowing through the RO concentrated water return line L51 by selecting the number of open valves.

1,1A pure water production equipment (reverse osmosis membrane separation equipment)
5 Pressure pump 7 RO membrane module (reverse osmosis membrane module)
8 Pre-stage pressurizing pump (pressurizing pump)
10 Pre-stage RO membrane module (reverse osmosis membrane module)
S3 Turbidity sensor (water quality detection means)
S4 Iron concentration sensor (water quality detection means)
TOC1 First TOC sensor (water quality detection means, total organic carbon sensor)
W1 Supply water W2 Permeated water, Pre-stage permeated water W3 Concentrated water

Claims (4)

At least one reverse osmosis membrane module for separating the feed water into permeate and concentrated water;
A pressurizing pump for discharging supply water toward the reverse osmosis membrane module;
Water quality detection means for detecting the quality of at least one of supply water and concentrated water ;
When the ratio of the flow rate of the concentrated water to the flow rate of pre Kigyaku osmosis membrane permeated water separated by the module as a circulation ratio of the reverse osmosis membrane module, according to the water quality detected by the quality detecting means, said reverse circulation ratio in osmosis membrane module so as to fall within a predetermined circulation ratio, flow rate of feed water, the flow rate of the permeate, and a control unit to set at least one of the flow rate of the concentrated water A reverse osmosis membrane separation device. Wherein the control unit is configured such that a predetermined circulation ratio is within the range specified in the 2-10, the flow rate of feed water, claim to set at least one of the flow rate of the permeate flow rate, and concentrated water 1 The reverse osmosis membrane separation apparatus described in 1. The control unit decreases the circulation ratio when the water quality detected by the water quality detection means is improved, or increases the circulation ratio when the water quality detected by the water quality detection means is reduced. , the flow rate of feed water, permeate flow rate, and reverse osmosis membrane separation apparatus according to claim 1 or 2 to set the at least one of the flow rate of the concentrated water. The water quality detection means includes a turbidity detection sensor for detecting turbidity of either supply water or concentrated water, an iron concentration detection sensor for detecting iron concentration of either supply water or concentrated water, and any of supply water and concentrated water. The reverse osmosis membrane separation device according to any one of claims 1 to 3, which is any one or more of all organic carbon detection sensors for detecting the total organic carbon.

Images