JP2014188437A - Membrane separation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a membrane separation apparatus in which a part of concentrated water can stably be returned to the upstream side of a pressure pump.SOLUTION: The membrane separation apparatus comprises: a membrane module 7; a pressure pump 5 for discharging supply water W1 toward the membrane module 7; a return line L51 for returning a part W31 of concentration water W3 to the upstream side of the pressure pump 5; a water discharge line L61 for discharging a remainder W32 of the concentration water W3 to the outside; a circulation pump 21 which is arranged on the return line L51 and used for discharging the part W31 of the concentration water W3 toward the upstream side of the pressure pump 5; pressure detecting means PSW for detecting the pressure of the supply water W1 to be circulated on the upstream side of the pressure pump 5 on a supply water line L1 as a detected pressure value; and a control part 30 which controls so that the pressure pump 5 is stopped and the circulation pump 21 is driven when the detected pressure value exceeds a predetermined pressure threshold or the pressure pump 5 is driven and the circulation pump 21 is stopped when the detected pressure value falls below the predetermined pressure threshold.

Description

  The present invention relates to a membrane separation device including a membrane module.

  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 produced by subjecting raw water such as groundwater or tap water to membrane separation treatment with a membrane module such as a reverse osmosis membrane module (hereinafter also referred to as “RO membrane module”). By performing membrane separation treatment with the membrane module, the raw water is separated into permeated water from which dissolved salts and the like are removed and concentrated water from which dissolved salts and the like are concentrated.

  Conventionally, as a membrane separation device, a membrane module that separates feed water into permeate and concentrated water, a feed water line that circulates feed water through the membrane module, and a feed water line that is provided in the feed water line and directs feed water to the membrane module A pressure pump for discharging, a return line for returning a part of the concentrated water separated by the membrane module to the upstream side of the pressure pump, and a part of the concentrated water upstream of the pressure pump provided in the return line A membrane separation device including a circulation pump that discharges toward the side is known (for example, Patent Document 1).

  In the membrane separation apparatus described in Patent Document 1, a part of the concentrated water separated by the membrane module is circulated to the supply water, and the supply water mixed with the concentrated water is supplied to the membrane module. That is, in the membrane module, a cross-flow type separation operation for producing permeated water is performed while circulating the feed water with a circulation pump. As a result, a part of the concentrated water flows into the upstream side of the membrane module, and suspended substances (for example, insoluble colloidal iron) contained in the supply water are deposited on the surface and pores of the membrane. It is said that a phenomenon called fouling can be suppressed.

JP 2003-260449 A

By the way, in recent years, in the membrane module, the water permeability of the membrane has been improved, and a high flux permeate can be produced at a low operating pressure. In the membrane separation apparatus described in Patent Document 1, a membrane module is provided on the downstream side of the pressure pump. For this reason, when a membrane module with improved water permeability of the membrane is used, the pressure on the downstream side of the pressure pump (that is, the pressure of the concentrated water flowing out of the membrane module) may be low. In this case, if the pressure on the upstream side of the pressurizing pump is high, it is difficult to return a part of the concentrated water separated by the membrane module to the upstream side of the pressurizing pump.
Therefore, a membrane separation device that can stably return a part of the concentrated water to the upstream side of the pressure pump in the crossflow type membrane separation device is desired.

  The present invention comprises a pressurizing pump for discharging supply water toward the membrane module, and a return line for returning a part of the concentrated water separated by the membrane module to the upstream side of the pressurizing pump. It is an object of the present invention to provide a membrane separation device that can stably return a part of it to the upstream side of a pressure pump.

  The present invention provides a membrane module that separates supply water into permeated water and concentrated water, a supply water line that circulates supply water to the membrane module, and the supply water line. The supply water is directed to the membrane module. A pressure pump for discharging the liquid, a return line for returning a part of the concentrated water separated by the membrane module to the upstream side of the pressure pump, and a remaining portion of the concentrated water separated by the membrane module being discharged to the outside. Drainage line, a circulation pump that is provided in the return line and that discharges a part of the concentrated water separated by the membrane module toward the upstream side of the pressurization pump, and the pressurization pump in the supply water line Pressure detecting means for detecting the pressure of the feed water flowing upstream as a detected pressure value, and when the detected pressure value exceeds a predetermined pressure threshold, the pressure pump is stopped. And a control unit that controls to drive the circulation pump, or that controls to drive the pressurization pump and stop the circulation pump when the detected pressure value is lower than a predetermined pressure threshold value; The present invention relates to a membrane separation apparatus.

  According to the present invention, a pressurizing pump for discharging supply water toward the membrane module and a return line for returning a part of the concentrated water separated by the membrane module to the upstream side of the pressurizing pump are provided. It is possible to provide a membrane separation device capable of stably returning a part of the concentrated water to the upstream side of the pressure pump.

1 is an overall schematic diagram of a pure water production apparatus 1 according to the present embodiment. It is the front | former part part of the whole block diagram of the pure water manufacturing apparatus 1 which concerns on this embodiment. It is the middle stage part of the whole block diagram of the pure water manufacturing apparatus 1 which concerns on this embodiment. It is a back | latter stage part of the whole block diagram of the pure water manufacturing apparatus 1 which concerns on this embodiment. 4 is a flowchart showing a processing procedure for executing control of the pressurization pump 5 and the circulation pump 21 by the control unit 30.

Hereinafter, an embodiment when the membrane separation apparatus according to the present invention is applied to a pure water production apparatus will be described.
(First embodiment)
First, the pure water manufacturing apparatus 1 which concerns on this embodiment is demonstrated, referring drawings. FIG. 1 is an overall schematic diagram of a pure water production apparatus 1 according to the present embodiment. FIG. 2A is a front part of the entire configuration diagram of the pure water producing apparatus 1 according to the present embodiment. FIG. 2B is a middle part of the entire configuration diagram of the pure water producing apparatus 1 according to the present embodiment. FIG. 2C is a rear part of the entire configuration diagram of the pure water producing apparatus 1 according to the present 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 production apparatus 1 according to the present embodiment includes a first option device OP1, a prefilter 4, a second option device OP2, a pressurization pump 5, a pressurization side inverter 6, RO membrane module 7 as a membrane module, third optional device OP3, first flow path switching valve V71, electrodeionization stack (hereinafter also referred to as “EDI stack”) 16, circulation pump 21, and circulation side The inverter 22, the second flow path switching valve V <b> 72, the fourth optional device OP <b> 4, the control unit 30, the input operation unit 40, the DC power supply device 50, and the display unit 60 are provided.

  The first option device OP <b> 1 to the fourth option device OP <b> 4 are devices that are attached to 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 OP <b> 1 includes a water softener 2 and an activated carbon filter 3. The second optional device OP2 includes a hardness sensor S1 and a residual chlorine sensor S2. The third optional device OP3 includes a decarboxylation device 15. The fourth optional device OP4 includes a second specific resistance sensor RS2, a total organic carbon sensor TOC, and a third temperature sensor TE3.

  As shown in FIG. 1, the pure water production apparatus 1 includes a supply water line L1, a permeate water line L21, a RO permeate return line L41, a RO concentrate water line L50, and a RO concentrate water as a return line. A return line L51, an RO concentrated water discharge line L61 as a discharge line, a desalted water line L3, a desalted water return line L42, and an EDI concentrated water line L52 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 supply water replenishment. Valve V31, first drain valve V32 to third drain valve V34, first constant flow valve V51 to fourth constant flow valve V54, first check valve V61 to fifth check valve V65, and first pressure Meter P1 to sixth pressure meter P6, first pressure sensor PS1 to fourth pressure sensor PS4, pressure switch PSW as pressure detecting means, first temperature sensor TE1 and second temperature sensor TE2, and first flow rate sensor FM1 and 2nd flow sensor FM2, 1st electric conductivity sensor EC1, and 1st specific resistance sensor RS1 are provided.

  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, first temperature sensor TE1 to third temperature sensor TE3, first pressure sensor PS1 to fourth pressure sensor PS4, first flow rate sensor FM1 and second flow rate sensor FM2, The first electrical conductivity sensor EC1, the first specific resistance sensor RS1, the second specific resistance sensor RS2, the total organic carbon sensor TOC, the hardness sensor S1, the residual chlorine sensor S2, and the like 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 side input port (the inlet of 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 activated carbon filter 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. In addition, after the connecting portion J5, as shown in FIG. 2B, as shown in FIG. A pump 5, a connection portion J9, and an 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 an automatic 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 activated carbon filter 3 is a device that removes chlorine components (mainly free residual chlorine) contained in the soft water W12 (feed water W1). The activated carbon filter 3 has a filtration tower in which a filter medium bed made of activated carbon is housed in a pressure tank. The activated carbon filter 3 purifies the soft water W12 (feed water W1) by decomposing and removing the chlorine component contained in the soft water W12, adsorbing and removing organic components, and capturing suspended substances.

  The prefilter 4 is a filter that removes fine particles contained in the soft water W12 (supply water W1) purified by the activated carbon filter 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.

  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. As shown in FIG. 2A, the hardness sensor S1 and the residual chlorine sensor S2 are connected to the supply water line L1 at the connection portion J5 via the measurement line L110. 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 and the residual chlorine sensor S2 are electrically connected to the control unit 30. The hardness leak amount measured by the hardness sensor S1 and the chlorine leak amount measured by the residual chlorine sensor S2 are transmitted to the control unit 30 as detection signals, respectively.

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

  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 line L50 is a line through which the concentrated water W3 separated by the RO membrane module 7 is circulated. The upstream end of the RO concentrated water line L50 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 line L50 is connected to the RO concentrated water return line L51 and the RO concentrated water discharge line L61 at the connection portion J53.

  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 via the RO concentrated water line L50. The upstream end of the RO concentrated water return line L51 is connected to the connecting portion J53. 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 circulation pump 21.

  The circulation pump 21 is a device that sucks a part W31 of the concentrated water W3 flowing through the RO concentrated water return line L51 and pumps (discharges) it toward the upstream side of the pressurizing pump 5. The circulation pump 21 is supplied with drive power whose frequency is converted from the circulation-side inverter 22. Circulation pump 21 is driven at a rotational speed corresponding to the frequency of the supplied drive power (hereinafter also referred to as “drive frequency”).

  The circulation side inverter 22 is an electric circuit (or a device having the circuit) for supplying the circulation pump 21 with driving power whose frequency is converted. The circulation side inverter 22 is electrically connected to the control unit 30. A command signal is input from the control unit 30 to the circulation-side inverter 22. The circulation-side inverter 22 outputs drive power having a drive frequency corresponding to the command signal (current value signal or voltage value signal) input by the control unit 30 to the circulation pump 21.

  When the circulation pump 21 is driven by the circulation side inverter 22, a part W 31 of the concentrated water W 3 is circulated to the upstream side of the pressurizing pump 5, and the concentrated water is supplied to the soft water W 12 that is circulated upstream of the pressurizing pump 5. The supply water mixed with W3 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 circulation pump 21.

  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 to the outside of the apparatus via the RO concentrated water line L50. The upstream end portion of the RO concentrated water discharge line L61 is connected to the connection portion J53. 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 the pressure of the supply water W1 that circulates upstream of the pressurization pump 5 in the supply water line L1. For example, the pressure switch PSW 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. In the present embodiment, the pressure switch PSW outputs a detection signal when the pressure of the supply water W1 flowing upstream from the pressurization pump 5 in the supply water line L1 exceeds a predetermined pressure threshold value. For example, as the predetermined pressure threshold, since the pressure of the supply water W1 upstream of the pressurizing pump 5 in the supply water line L1 is too high, a part of the concentrated water W3 is returned to the upstream side of the pressurizing pump 5. The lower limit pressure value that cannot be set is set. For example, the predetermined pressure threshold is set to 0.1 MPa.

  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 total organic carbon sensor TOC is a device that detects the amount of organic carbon in the desalted water W6 flowing through the desalted water line L8. Organic carbon is carbon in organic matter present in water. The total organic carbon sensor TOC 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 all organic carbon sensor TOC is electrically connected to the control unit 30. The total organic carbon content of the demineralized water W6 detected by the total organic carbon sensor TOC 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.

  When the detected pressure value detected by the pressure switch PSW exceeds a predetermined pressure threshold value, the control unit 30 controls the pressurizing-side inverter 6 to stop the pressurizing pump 5 and drives the circulation pump 21. Thus, the circulation side inverter 22 is controlled. In addition, when the detected pressure value detected by the pressure switch PSW falls below a predetermined pressure threshold value, the control unit 30 controls the pressurization-side inverter 6 so as to drive the pressurization pump 5 and the circulation pump 21. The circulation side inverter 22 is controlled so as to be stopped.

  In the present embodiment, a detection signal is output from the pressure switch PSW when the detected pressure value detected by the pressure switch PSW exceeds a predetermined pressure threshold value. Therefore, when the detection signal is output from the pressure switch PSW, the control unit 30 controls the pressurizing side inverter 6 so as to stop the pressurizing pump 5 and the circulating side inverter so as to drive the circulating pump 21. 22 is controlled. In addition, when the detection signal is not output from the pressure switch PSW, the control unit 30 controls the pressurization-side inverter 6 so as to drive the pressurization pump 5 and the circulation-side inverter 22 so as to stop the circulation pump 21. To control.

  In this way, when the pressure of the supply water W1 flowing upstream from the pressurizing pump 5 exceeds a predetermined pressure threshold, only the circulation pump 21 is driven to add a part W31 of the concentrated water W3. It can be returned stably to the upstream side of the pressure pump 5. Thereby, it is suppressed that the flow velocity of the surface of the RO membrane on the primary side of the RO membrane module 7 decreases. Therefore, fouling on the surface of the RO membrane in the RO membrane module 7 is suppressed, and the membrane clogging of the RO membrane is difficult to occur.

  On the other hand, when the pressure of the supply water W1 flowing upstream from the pressurization pump 5 is below a predetermined pressure threshold, only the pressurization pump 5 is driven to supply the supply water W1 to the RO membrane module 7. The RO membrane module 7 can produce the permeate W2. Therefore, based on the pressure of the supply water W1 which circulates upstream from the pressurizing pump 5, one of the circulation pump 21 or the pressurizing pump 5 can be driven when necessary. Therefore, power consumption can be suppressed in the operations of the pressurization pump 5 and the circulation pump 21.

  Next, control of the pressurization pump 5 and the circulation pump 21 by the control unit 30 will be described. FIG. 3 is a flowchart showing a processing procedure for controlling the pressurization pump 5 and the circulation pump 21 by the control unit 30. 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 determines whether or not a detection signal is output from the pressure switch PSW. The detection signal from the pressure switch PSW is output when the detected pressure value exceeds a predetermined pressure threshold value. If a detection signal is output from the pressure switch PSW (YSE), the process proceeds to step ST102. If the detection signal is not output from the pressure switch PSW (NO), the process proceeds to step ST103.

  In step ST102, the control unit 30 controls the pressurization-side inverter 6 so as to stop the pressurization pump 5, and controls the circulation-side inverter 22 so as to drive the circulation pump 21. Thereby, the permeated water W2 can be produced by the operating pressure of the circulation pump 21, while returning a part W31 of the concentrated water W3 stably to the upstream side of the pressurizing pump 5. Thereafter, the process ends (returns to step ST101).

  In step ST103, the control unit 30 controls the pressurization-side inverter 6 so as to drive the pressurization pump 5, and controls the circulation-side inverter 22 so as to stop the circulation pump 21. Thereby, the pressurizing pump 5 discharges the supply water W <b> 1 toward the RO membrane module 7. As a result, the permeated water W2 can be produced while returning a part W31 of the concentrated water W3 to the upstream side of the pressurizing pump 5 only by the operating pressure of the pressurizing pump 5. Thereafter, the process ends (returns to step ST101).

According to the pure water manufacturing apparatus 1 which concerns on this embodiment mentioned above, the following effects are show | played, for example.
In this embodiment, the RO membrane module 7, the pressure pump 5 that discharges the supply water W <b> 1 toward the RO membrane module 7, and the RO that returns a part W <b> 31 of the concentrated water W <b> 3 to the upstream side of the pressure pump 5. The concentrated water return line L51, the RO concentrated water discharge line L61 for discharging the remaining portion W32 of the concentrated water W3 to the outside, the RO concentrated water return line L51, and a portion W31 of the concentrated water W3 upstream of the pressurizing pump 5 A circulation pump 21 that discharges toward the side, a pressure switch PSW that detects the pressure of the supply water W1 that circulates upstream of the pressurization pump 5 in the supply water line L1 as a detection pressure value, and a detection pressure value that is predetermined. When the pressure threshold value is exceeded, the pressurization pump 5 is controlled to stop and the circulation pump 21 is driven, or when the detected pressure value falls below a predetermined pressure threshold value. And a control unit 30 for controlling to stop the and circulating pump 21 drives the pressure pump 5, a.

  Therefore, a part of the concentrated water W3 can be stably returned to the upstream side of the pressurizing pump 5. Thereby, it is suppressed that the flow velocity of the surface of the RO membrane on the primary side of the RO membrane module 7 decreases. Therefore, fouling on the surface of the RO membrane in the RO membrane module 7 is suppressed.

  Further, only one of the circulation pump 21 or the pressurization pump 5 can be driven based on the detected pressure value of the supply water W1 that circulates upstream from the pressurization pump 5. Therefore, power consumption can be suppressed in the operations of the pressurization pump 5 and the circulation pump 21.

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 said embodiment, although the membrane module was comprised as the RO membrane module 7 and the membrane separator was comprised as the pure water manufacturing apparatus 1, it is not restrict | limited to this. As membrane modules, besides RO membrane modules, NF membrane modules having nanofiltration membranes with pores looser than reverse osmosis membranes, UF membrane modules having ultrafiltration membranes, and MF membrane modules having microfiltration membranes Etc. can also be applied.

  In the above embodiment, the pressure switch PSW is used as the pressure detection means, but the present invention is not limited to this. A pressure sensor may be used as the pressure detection means. When the pressure sensor is used, the control unit 30 is configured to determine whether or not the detected pressure value detected by the pressure sensor is above or below a predetermined pressure threshold, and based on the determination result. The pressure pump 5 and the circulation pump 21 can be controlled to be driven or stopped.

  In the embodiment, the example in which the drainage flow rate of the concentrated water W3 is adjusted stepwise by selecting the number of opened first drain valve V32 to third drain valve V34 has been described. 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 drainage flow rate of the concentrated water W3 can be adjusted by transmitting a current value signal from the control unit (30) to the proportional control valve to control the opening of the valve body.

  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 as a feedback value to the control unit (30).

  In the embodiment, the example in which the soft water W12 from which the hardness component contained in the raw water W11 is removed is used as the supply water W1 has been described. Not only this but the raw water W11 which pre-processed with the iron removal manganese removal apparatus, the sand filtration apparatus, etc. is good also as supply water W1. In addition, as raw | natural water W11, groundwater, a tap water, etc. can be used, for example.

1 Pure water production equipment (membrane separation equipment)
5 Pressure pump 7 RO membrane module (membrane module)
21 Circulating pump 30 Control part L1 Supply water line L51 RO Concentrated water return line (return line)
L61 RO concentrated water discharge line (discharge line)
PSW Pressure switch (Pressure detection means)
W1 Supply water W2 Permeated water W3 Concentrated water W31 Part of concentrated water W32 The remainder of concentrated water

Claims (1)

A membrane module that separates feed water into permeate and concentrated water;
A supply water line for distributing supply water to the membrane module;
A pressure pump that is provided in the supply water line and discharges the supply water toward the membrane module;
A return line for returning a part of the concentrated water separated by the membrane module to the upstream side of the pressure pump;
A drainage line for discharging the remainder of the concentrated water separated by the membrane module to the outside;
A circulation pump that is provided in the return line and discharges a part of the concentrated water separated by the membrane module toward the upstream side of the pressurizing pump;
Pressure detecting means for detecting, as a detected pressure value, the pressure of the feed water flowing upstream from the pressurizing pump in the feed water line;
When the detected pressure value exceeds a predetermined pressure threshold, the pressurizing pump is stopped and the circulation pump is driven, or when the detected pressure value is lower than the predetermined pressure threshold, And a control unit that controls to drive the pressurizing pump and stop the circulation pump.

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