JP6390312B2 - Filtration system - Google Patents

Description

  The present invention relates to a filtration system including a filtration device group including a plurality of filtration devices.

  There is known a membrane filtration device (filtration device) including a membrane module that produces treated water (permeated water) from raw water (treated water). Conventionally, a filtration system in which a plurality of membrane filtration devices are connected in parallel has been proposed in order to cope with a case where treated water consumed at a demand point cannot be produced by a single membrane filtration device (see, for example, Patent Document 1). ).

  In such a filtration system in which a plurality of membrane filtration devices are connected in parallel, each of the plurality of membrane filtration devices has a maximum water flow state (the largest water flow state with respect to the rated flow rate, For example, it may be controlled in order to handle a load required from the demand point until the water flow rate reaches 80% of the rated flow rate. When controlled in this way, for example, in a plurality of membrane filtration devices, the first membrane filtration device does not operate until the first membrane filtration device reaches the maximum water flow state. It is controlled to produce treated water only by the membrane filtration device of the eye. When the first membrane filtration device reaches the maximum water flow state, the second membrane filtration device is controlled to start operation. Until the second membrane filtration device reaches the maximum water flow state, the third membrane filtration device is not operated, and the first and second membrane filtration devices produce the treated water. To be controlled. The third and subsequent membrane filtration devices are also controlled so that this operation is executed sequentially.

JP 2010-162501 A

  In the filtration system controlled as described above, for a plurality of membrane filtration devices, the accumulated water passage time becomes longer as the operation start is earlier, and the accumulated water passage time becomes shorter as the operation start is delayed. As a result, the accumulated water passage time to the membrane filtration device is biased, and the clogging of the membrane tends to proceed for a specific membrane filtration device having a long accumulated water passage time.

  Therefore, an object of the present invention is to provide a filtration system in which clogging of a membrane hardly progresses in a filtration system including a filtration device group including a plurality of filtration devices.

The present invention provides a filtering device group including a plurality of filtering devices capable of producing permeated water from treated water by continuously changing the load factor, and a required load that is a required permeate flow rate. A control unit that controls a flow rate of permeated water produced by the filter device group, wherein the plurality of filter devices include a unit flow rate that is a unit of a variable flow rate. A flow rate is set, and the control unit calculates a deviation amount between a required water flow rate required according to the required load and an output water flow rate output by the filtering device group. And when the required flow rate is larger than the output flow rate, a low load factor filtration device is selected from the plurality of filtration devices, and the required flow rate is smaller than the output flow rate. A filtration device having a high load factor among the plurality of filtration devices A filtration device selection unit that selects the flow rate of the filtration device selected by the filtration device selection unit when the required flow rate is larger than the output flow rate, and the unit flow rate is increased, When the required water flow rate is smaller than the output water flow rate, the deviation control unit calculates the flow rate of the filtration device selected by the filtration device selection unit by the unit water flow rate. A determination unit that determines whether the deviation amount is greater than or equal to the unit water flow rate, and the output control unit is determined by the determination unit that the deviation amount is greater than or equal to the unit water flow rate. In the case, the flow rate of the filtration device selected by the filtration device selection unit is changed, and the deviation calculation unit, when the flow rate of the selected filtration device is changed by the output control unit, Necessary water flow rate and flow Deviation between the output through water flow rate of the filtration device group after the flow changes to a filtration system that calculated.

  In addition, the unit water flow rate is individually set for each of the plurality of filtration devices, and the determination unit is greater than or equal to the unit water flow rate of the filtration device selected by the filtration device selection unit. It is preferable to determine whether it exists.

  Moreover, the priority order is set to the plurality of filtration devices, and the filtration device selection unit is configured such that the required water flow rate is higher than the output water flow rate when the load factors of the plurality of filtration devices are equal. It is preferable to select the filtering device with the highest priority when the flow rate is large, and to select the filtering device with the lowest priority when the required flow rate is smaller than the output flow rate.

  The unit water flow rate is preferably set to 1% to 5% of the rated flow rate of the filtration device.

  ADVANTAGE OF THE INVENTION According to this invention, in a filtration system provided with the filtration apparatus group containing a several filtration apparatus, the filtration system with which clogging of a film | membrane cannot progress easily can be provided.

It is a figure showing the outline of filtration system 1 concerning one embodiment of the present invention. It is a figure which shows the outline of the membrane filtration apparatus group 2 which concerns on one Embodiment of this invention. 3 is a functional block diagram illustrating a configuration of a control unit 32. FIG. It is a figure showing the outline of membrane filtration device 20 concerning one embodiment of the present invention. It is a figure explaining the opening-and-closing state of each valve in each process. It is a flowchart which shows operation | movement of a filtration system. It is a schematic diagram which shows an example of operation | movement of the filtration system of 1st Embodiment. It is a schematic diagram which shows an example of operation | movement of the filtration system of 1st Embodiment. It is a schematic diagram which shows an example of operation | movement of the filtration system of 1st Embodiment. It is a schematic diagram which shows an example of operation | movement of the filtration system of 1st Embodiment. It is a schematic diagram which shows an example of operation | movement of the filtration system of 1st Embodiment. It is a schematic diagram which shows an example of operation | movement of the filtration system of 1st Embodiment. It is a schematic diagram which shows an example of operation | movement of the filtration system of 1st Embodiment. It is a schematic diagram which shows an example of operation | movement of the filtration system of 1st Embodiment. It is a schematic diagram which shows an example of operation | movement of the filtration system of 2nd Embodiment. It is a schematic diagram which shows an example of operation | movement of the filtration system of 2nd Embodiment. It is a schematic diagram which shows an example of operation | movement of the filtration system of 2nd Embodiment. It is a schematic diagram which shows an example of operation | movement of the filtration system of 2nd Embodiment. It is a schematic diagram which shows an example of operation | movement of the filtration system of 2nd Embodiment.

  Hereinafter, the filtration system 1 which concerns on embodiment of this invention is demonstrated, referring drawings. FIG. 1 is a diagram showing an outline of a filtration system 1 according to an embodiment of the present invention. FIG. 2 is a diagram showing an outline of the membrane filtration device group 2 according to one embodiment of the present invention. FIG. 3 is a functional block diagram showing the configuration of the control unit 32.

First, the overall configuration of the filtration system 1 of the present invention will be described with reference to FIG.
As shown in FIG. 1, a filtration system 1 includes a plurality of (five) membrane filtration devices (filtration devices) 20 (filtration devices) that can produce permeated water W2 from raw water W1 as treated water. Group) 2, a plurality of raw water pumps 3, a plurality of first inverters 4, a treated water tank 16 that collects the permeated water W 2 produced in the plurality of membrane filtration devices 20 as treated water W 6, and this treated water tank 16, a water level sensor 17 that detects the level of the treated water W6 (permeated water W2) stored in the interior of the tank 16, a backwash water tank 7, a backwash water pump 5, a second inverter 6, and a chemical addition device 8 And a number control device 30 having a control unit 32 for controlling the flow rate of the permeated water W2 produced by the membrane filtration device group 2.

  The filtration system 1 includes a raw water line L11, a local raw water line L12, a permeate water line L21, a local permeate water line L22, a backwash water line L3, and a water distribution line L7. The “line” in the present specification is a general term for lines capable of flowing a fluid such as a flow path, a path, and a pipeline.

  The raw water line L11 is a line that supplies the raw water W1 to the plurality of membrane filtration devices 20. The upstream end of the raw water line L11 is connected to a supply source (not shown) of the raw water W1. The downstream end of the raw water line L11 is branched to the local raw water line L12 toward the plurality of membrane filtration devices 20, respectively. The raw water W1 flowing through the raw water line L11 is distributed to the plurality of membrane filtration devices 20 through the plurality of local raw water lines L12 during the fresh water generation operation.

Each of the plurality of local raw water lines L12 is provided with a raw water pump 3.
The raw water pump 3 is a device that sucks the raw water W1 flowing through the local raw water line L12 and pumps (discharges or sends) the raw water W1 toward the membrane filtration device 20. The raw water pump 3 is supplied with driving power having a frequency converted from the first inverter 4. The raw water pump 3 is driven at a rotational speed corresponding to the frequency of the input drive power (hereinafter also referred to as “drive frequency”).

  The first inverter 4 is an electric circuit (or a device having the circuit) that supplies the raw water pump 3 with driving power whose frequency has been converted. The first inverter 4 is electrically connected to each local control unit 22 (described later) of the membrane filtration device 20. A frequency designation signal (that is, a command signal) is input to the first inverter 4 from the local control unit 22 (described later). The first inverter 4 supplies driving power having a driving frequency corresponding to a frequency designation signal (current value signal or voltage value signal) input by the local control unit 22 (described later) via the signal line 53 to the raw water pump 3. Output.

  Here, the rotation of the raw water pump 3 is performed by inputting a frequency designation signal to the first inverter 4 based on a flow rate detection signal from a flow rate sensor 12 (see FIG. 4 described later) provided in each membrane filtration device 20. The speed can be varied. According to this configuration, the feedback control based on the flow rate of the permeate water W2 detected by the flow rate sensor 12 can be controlled so as to keep the flow rate of the permeate water W2 constant. As a result, as the cake layer grows on the membrane surface of each membrane module 21, the rotational speed of the raw water pump 3 is automatically adjusted to increase the flow rate of the permeated water W2 even if the water flow resistance between the membranes increases. It can be controlled constantly.

  As shown in FIG. 1, the plurality of membrane filtration devices 20 each include a plurality (four) of membrane modules 21. In the present embodiment, the plurality of membrane filtration devices 20 can manufacture the permeated water W2 from the raw water W1 at the same rated flow rate. Further, each of the plurality of membrane filtration devices 20 is electrically connected to the number control device 30. Details of the membrane filtration device 20 will be described later.

  The permeated water line L <b> 21 is a line for sending permeated water W <b> 2 manufactured by the plurality of membrane filtration devices 20 to the treated water tank 16. The upstream end of the permeate line L21 branches to a plurality of local permeate lines L22 and is connected to the membrane modules 21 of the membrane filtration device 20 respectively. The downstream end of the permeate line L <b> 21 is connected to the treated water tank 16. In the permeated water line L21, a connecting portion J4 and a treated water tank 16 are provided in order from the upstream side.

  The membrane filtration device group 2 manufactures the permeated water W2 to be supplied to the treated water use facility 18 as a load device. The permeated water W2 produced by the membrane filtration device group 2 is replenished to the treated water tank 16 via the permeated water line L2.

  An upstream end portion of the backwash water line L3 is connected to the connection portion J4. The backwash water line L3 is branched from the permeate water line L21 at the connection portion J4, and passes through the backwash water tank 7 described later at the connection portion J3 (see FIG. 4) inside the membrane filtration device 20. This is a line joined to the line L21. The upstream end portion of the backwash water line L3 is connected to the connection portion J4. The downstream end portion of the backwash water line L3 is branched and connected to the connection portion J3 of the permeate water line L21 inside the membrane filtration device 20 (see FIG. 4). A part of the permeated water W2 produced in the plurality of membrane modules 21 is circulated in the backwash water line L3 in order to execute a backwashing process (described later) in the plurality of membrane modules 21.

  As shown in FIG. 1, the backwashing water line L3 is provided with a connecting part J4, a backwashing water tank 7, a backwashing water pump 5, a connecting part J5, and a plurality of membrane filtration devices 20 in order from the upstream side. ing.

  The backwash water tank 7 circulates a part of the permeate water W2 produced in the plurality of membrane modules 21 through the backwash water line L3 for the backwash process, and the backwash water W3 (permeate water W2). ) As a storage tank.

  The backwash water pump 5 is a device that sucks backwash water W3 (permeate water W2) flowing through the backwash water line L3 and pumps (discharges) the water to the plurality of membrane modules 21 in the backwash process. is there. The backwash water pump 5 can change the flow rate of the backwash water W4. The backwash water pump 5 is supplied with driving power having a frequency converted from the second inverter 6. The backwash water pump 5 is driven at a rotational speed corresponding to the frequency of the input drive power (hereinafter also referred to as “drive frequency”).

  The second inverter 6 is an electric circuit (or a device having the circuit) for supplying the backwash water pump 5 with driving power whose frequency is converted. The second inverter 6 is electrically connected to the number control device 30 via the signal line 54. A frequency designation signal is input from the number control device 30 to the second inverter 6. The second inverter 6 outputs drive power having a drive frequency corresponding to the frequency designation signal (current value signal or voltage value signal) input by the local control unit 22 to the backwash water pump 5 via the signal line 54. .

  A drug addition device 8 is connected to the connecting portion J5. The drug addition device 8 is a device that adds (supplies) a drug to the backwash water W3 flowing into the plurality of membrane modules 21 in the backwash process. In order to maintain the filtration performance of the plurality of membrane modules 21, by adding a chemical to the backwash water W3 in the backwash process, the contaminants deposited on the surface of the membrane are removed by chemical washing. For example, an oxidizing agent is used as the drug, and sodium hypochlorite or the like is used as the oxidizing agent.

  The drug addition device 8 supplies the drug to the backwash water W3 in proportion to the flow rate of the backwash water W3 flowing through the backwash water line L3, for example, once for a plurality of backwash processes. The addition of the drug is performed, for example, once for a plurality of back washing steps, for example, about once a day. The drug addition device 8 is electrically connected to the number control device 30 via the signal line 55. The addition of the drug in the drug adding device 8 is controlled by the number control device 30.

The treated water tank 16 collects the permeated water W2 produced by the membrane filtration device group 2 and stores it as treated water W6. The treated water tank 16 is connected to a plurality of membrane filtration devices 20 constituting the membrane filtration device group 2 via the permeate line L21.
The downstream side of the treated water tank 16 is connected to the treated water use facility 18 via a water distribution line L7. The treated water W6 (permeated water W2) stored in the treated water tank 16 is supplied to the treated water use facility 18 as the treated water W6 through the water distribution line L7.

  The treated water tank 16 is provided with a water level sensor 17. The water level sensor 17 is a device that detects the water level of the treated water W6 (permeated water W2) stored in the treated water tank 16. The water level sensor 17 is electrically connected to the local control unit 22 of the number control device 30. The water level of the treated water tank 16 measured by the water level sensor 17 (hereinafter also referred to as “detected water level value”) is output as a detection signal to the local control unit 22 of the number control device 30.

  The water level sensor 17 is electrically connected to the number control device 30 via the signal line 51. The water level sensor 17 measures the water level of the treated water W6 stored in the treated water tank 16 (treated water W6 (permeated water W2) manufactured and stored in the membrane filtration device group 2), and sets the measured water level. Such a signal (water level signal) is transmitted to the number control device 30 via the signal line 51. In the present embodiment, the water level sensor 17 is, for example, a continuous level sensor, and for example, a capacitive sensor, a pressure sensor, an ultrasonic sensor, or the like is used. FIG. 1 shows an example in which a capacitive sensor is provided as the water level sensor 17.

  The number control device 30 is electrically connected to the plurality of membrane filtration devices 20 via the signal line 52. This number control device 30 determines the flow rate of the permeated water W2 produced by each membrane filtration device 20 based on the water level of the treated water W6 stored in the treated water tank 16 measured by the water level sensor 17. Control. Details of the number control device 30 will be described later.

The filtration system 1 described above can supply the permeated water W2 produced by the membrane filtration device group 2 to the treated water use facility 18 via the treated water tank 16.
The load (required load) required in the filtration system 1 is the consumption of the treated water W6 in the treated water use facility 18, and the treated water W6 (permeated water W2) requested from the demand point (treated water use facility 18). ). The number control device 30 of the treated water tank 16 in which the water level sensor 17 measures the fluctuation of the water level of the treated water W6 stored in the treated water tank 16 corresponding to the fluctuation of the consumption amount of the treated water W6. Calculated based on the water level (physical quantity) of the treated water W6 stored inside, the flow rate of the permeated water W2 produced by each membrane filtration device 20 constituting the membrane filtration device group 2 (water amount of the treated water W6) To control.

  Specifically, the demand load (consumption amount of the treated water W6, the flow rate of the treated water W6 requested from the treated water use facility 18) increases due to an increase in demand for the treated water use facility 18, and the treated water tank 16 If the amount of the treated water W6 supplied to the water is insufficient, the water level of the treated water W6 stored in the treated water tank 16 is lowered. On the other hand, the required load (consumption amount of the treated water W6, the flow rate of the treated water W6 requested from the treated water use facility 18) decreases due to a decrease in demand of the treated water use facility 18, and is supplied to the treated water tank 16. If the treated water W6 becomes excessive, the water level of the treated water W6 stored in the treated water tank 16 will rise. Therefore, the filtration system 1 can monitor the fluctuation of the required load based on the fluctuation of the water level of the treated water W6 stored in the treated water tank 16 measured by the water level sensor 17. And the filtration system 1 is a process required according to the consumption (required load) of the treated water W6 of the treated water use equipment 18 based on the water level of the treated water W6 stored in the treated water tank 16. Calculate the required water flow, which is the amount of water.

  Here, the several membrane filtration apparatus 20 which comprises the filtration system 1 of this embodiment is demonstrated. The membrane filtration device 20 of the present embodiment is a membrane filtration device capable of executing proportional control capable of producing the permeated water W2 from the raw water W1 by continuously changing the load factor. The load factor in the membrane filtration device 20 is the ratio of the flow rate of the permeate W2 to the rated flow rate of the membrane filtration device 20.

  As shown in FIG. 2, the membrane filtration device 20 capable of performing proportional control is at least from the minimum water flow state S1 (the smallest water flow state relative to the rated flow rate in the rated water flow state S3) to the maximum water flow state. In the range of S2 (the largest water flow state with respect to the rated flow rate in the rated water flow state S3), the membrane filtration device is capable of continuously controlling the water flow rate.

In this embodiment, the range between the load factor of the minimum water flow state S1 and the load factor of the maximum water flow state S2 is set to the optimum operation load factor zone.
The load factor of the minimum water flow state S1 is the ratio of the lower limit flow rate that can ensure the accuracy of detection of the water flow rate of the membrane filtration device 20 with respect to the rated flow rate of each membrane filtration device 20. If the water flow rate of the membrane filtration device 20 cannot be accurately grasped, the filtration system 1 cannot be controlled based on the load factor of each membrane filtration device 20, and therefore the load factor of the minimum water flow state S1 is set. In the present embodiment, for example, the load factor in the minimum water flow state S1 is set to 20% of the rated flow rate of the membrane filtration device 20.

  The load factor in the maximum water flow state S2 is a ratio of an upper limit flow rate at which the suspended substance is not pushed into the pores of the membrane of the membrane filtration device 20. When the suspended substance is pushed into the pores of the membrane of the membrane filtration device 20, an irreversible membrane blockage occurs in the membrane, making it impossible to recover the membrane. The load factor is set. In the present embodiment, for example, the load factor in the maximum water flow state S2 is set to 80% of the rated flow rate of the membrane filtration device 20.

  The membrane filtration device 20 capable of performing proportional control, for example, controls the opening of a raw water valve V1 (see FIG. 4) of the membrane filtration device 20 described later, thereby allowing the flow rate of the raw water W1 flowing through the local raw water line L12. To be adjusted.

  Further, continuously controlling the water flow rate means that a calculation or signal in the local control unit 22 to be described later is a digital method and is handled in stages (for example, output of the membrane filtration device 20 (flow rate of the permeated water W2). Even when the output is controlled in 1% increments).

In the present embodiment, the change of the water flow state between the water flow stop state S0 and the minimum water flow state S1 of the membrane filtration device 20 turns on / off the water flow of the membrane filtration device 20 (the valve body of the raw water valve V1). Controlled by opening and closing. In the range of the optimum operation load factor zone from the minimum water flow state S1 to the maximum water flow state S2, the water flow amount can be controlled continuously.
More specifically, a unit water flow rate U that is a unit of a variable water flow rate is set in each of the plurality of membrane filtration devices 20. Thereby, the membrane filtration apparatus 20 can change a water flow rate per unit water flow rate U in the range from the minimum water flow state S1 to the maximum water flow state S2.

The unit water flow rate U can be appropriately set according to the rated flow rate in the rated water flow state S3 of the membrane filtration device 20. From the viewpoint of improving the followability of the output water flow rate in the filtration system 1 to the required water flow rate, It is preferably set to 1% to 5% of the rated flow rate of the membrane filtration device 20. From the same viewpoint, the unit water flow rate U is preferably set to 20 L / h to 100 L / h in the case of a membrane filtration device with a rated flow rate of 2000 L / h.
The output water flow rate indicates the water flow rate output by the membrane filtration device group 2, and this output water flow rate is represented by the total value of the water flow rates output from each of the plurality of membrane filtration devices 20. Is done.

  In addition, a priority order is set for each of the plurality of membrane filtration devices 20. The priority order is used to select the membrane filtration device 20 that performs a water flow instruction or a water flow stop instruction. The priority order can be set, for example, using an integer value so that the lower the numerical value, the higher the priority order. As shown in FIG. 2, when priority of “1” to “5” is assigned to each of the first to fifth units of the membrane filtration device 20, the first unit has the highest priority and the fifth unit has priority. The ranking is the lowest. In the normal case, this priority order is changed at predetermined time intervals (for example, 24 hour intervals) under the control of the control unit 32 described later.

  A predetermined water flow pattern is set in the membrane filtration device group 2 described above. As a water flow pattern of the membrane filtration device group 2, for example, when water is passed from the membrane filtration device 20 having a high priority, and the load factor of the membrane filtration device 20 that is passing water exceeds a predetermined threshold value, Next, there is a water flow pattern in which the membrane filtration device 20 having a higher priority is passed.

Next, the detail of control of the water flow state of the several membrane filtration apparatus 20 by the filtration system 1 of this embodiment is demonstrated.
The number control device 30 is based on the water level signal from the water level sensor 17, the required water flow rate of the membrane filter device group 2 according to the required load, and the water flow state of each membrane filter device 20 corresponding to the required water flow rate. And the number control signal is transmitted to each membrane filtration device 20 (local control unit 22 described later). As shown in FIG. 1, the number control device 30 includes a storage unit 31 and a control unit 32.

  The storage unit 31 includes the content of instructions given to each membrane filtration device 20 under the control of the number control device 30 (control unit 32), information such as the water flow state received from each membrane filtration device 20, and a plurality of Information such as the setting conditions of the water flow pattern of the membrane filtration device 20, information on setting priority of the plurality of membrane filtration devices 20, information on setting related to the change (rotation) of the priority, and the like are stored.

  The control unit 32 gives various instructions to the respective membrane filtration devices 20 via the signal lines 52 and receives various data from the respective membrane filtration devices 20, thereby allowing water to flow through the five membrane filtration devices 20. Control state and priority. When each membrane filtration device 20 receives a signal for changing the water flow state from the number control device 30, the membrane filtration device 20 controls the membrane filtration device 20 according to the instruction.

As shown in FIG. 1, the membrane filtration device 20 includes a membrane module 21 through which water flows and a local control unit 22 that controls the water flow state of the membrane filtration device 20.
The local control unit 22 changes the water flow state of the membrane filtration device 20 according to the required load. Specifically, the local control unit 22 controls the water flow state of the membrane filtration device 20 based on the number control signal transmitted from the number control device 30 via the signal line 52.
Further, the local control unit 22 transmits a signal used in the number control device 30 to the number control device 30 via the signal line 52. Examples of the signal used in the number control device 30 include an actual water flow state of the membrane filtration device 20 and other data.

FIG. 3 is a functional block diagram showing the configuration of the control unit 32. The control unit 32 includes a necessary water flow rate calculation unit 321, an output water flow rate calculation unit 322, a deviation calculation unit 323, a membrane filtration device selection unit 324 (a filtration device selection unit), a determination unit 325, and an output control. Part 326.
The required water flow rate calculation unit 321 calculates the required water flow rate according to the required load based on the water level from the water level sensor 17.
The output water flow rate calculation unit 322 calculates an output water flow rate that is a water flow rate output by the membrane filtration device group 2 based on the water flow state of each membrane filtration device 20 transmitted from the local control unit 22. To do.

The deviation calculation unit 323 calculates a deviation amount between the required water flow rate and the output water flow rate.
Further, the deviation calculating unit 323, when the water flow rate of the selected membrane filtration device 20 is changed by the output control unit 326 described later, the required water flow rate and the membrane filtration device after the water flow rate change. The deviation amount from the output water flow rate of group 2 is calculated.

The membrane filtration device selection unit 324 selects the membrane filtration device 20 that changes the water flow rate when the required water flow rate varies.
Specifically, when the required water flow rate is larger than the output water flow rate, the membrane filtration device selection unit 324 selects a membrane filter device 20 having a low load factor from the plurality of membrane filter devices 20, and the required water flow rate. When the flow rate is smaller than the output water flow rate, the membrane filtration device 20 having a high load factor is selected from the plurality of membrane filtration devices 20.
In addition, when the load rate of the plurality of membrane filtration devices 20 is equal, the membrane filtration device selection unit 324 selects the membrane filtration device 20 having the highest priority when the required water flow rate is larger than the output water flow rate, and is necessary. When the water flow rate is smaller than the output water flow rate, the membrane filtration device 20 having the lowest priority is selected.

The determination unit 325 determines whether the deviation amount calculated by the deviation calculation unit 323 is greater than or equal to the unit water flow rate U.
The output control unit 326 changes the water flow rate of the membrane filtration device 20 selected by the membrane filtration device selection unit 324 when the determination unit 325 determines that the deviation amount is equal to or greater than the unit water flow rate U. Specifically, the output control unit 326 increases the water flow rate of the membrane filtration device selected by the membrane filtration device selection unit 324 by the unit water flow rate U when the required water flow rate is larger than the output water flow rate. Let Further, the output control unit 326 decreases the water flow rate of the membrane filtration device selected by the membrane filtration device selection unit 324 by the unit water flow rate U when the required water flow rate is smaller than the output water flow rate.

  Next, the structure of the several membrane filtration apparatus 20 is demonstrated with reference to FIG.4 and FIG.5. Here, the configuration will be described on behalf of one membrane filtration device 20, but the other membrane filtration devices 20 have the same configuration. FIG. 4 is a diagram showing an outline of the membrane filtration device 20 according to one embodiment of the present invention. FIG. 5 is a diagram for explaining the open / closed state of each valve in each step.

  As shown in FIG. 4, the membrane filtration device 20 of the present embodiment includes a plurality of membrane modules 21 and a local control unit 22. As shown in FIG. 4, the membrane filtration device 20 includes a local raw water line L12, a local permeate water line L22, a backwash water line L3, a first discharge line L4, a second discharge line L6, and a wash. An air supply line L5.

  The membrane filtration device 20 includes a raw water valve V1, a permeate water valve V2, a backwash water valve V3, a first discharge valve V4, a second discharge valve V6, an air flow rate adjustment valve V5, and temperature detection means. And a flow rate sensor 12 as a flow rate detection means.

  In FIG. 4, the electrical connection path is omitted, but the local control unit 22 performs the raw water valve V1, the permeate water valve V2, the backwash water valve V3, the first discharge valve V4, the second discharge valve V6, the air flow rate. The control valve V5, the first inverter 4 (see FIG. 1), the temperature sensor 11, the flow sensor 12 and the like are electrically connected.

  As shown in FIG. 4, raw water W1 as water to be treated flows through the local raw water line L12. The local raw water line L12 is a line through which the raw water W1 is distributed to the plurality of membrane modules 21. The local raw water line L12 is a line that connects a raw water W1 supply source (not shown) and the membrane module 21 via the raw water line L11 (see FIG. 1). The upstream end of the local raw water line L12 is connected to the downstream end of the raw water line L11. Further, the downstream end of the local raw water line L12 is branched and connected to the membrane module 21 respectively.

  As shown in FIG. 4, a raw water valve V1 is provided at a portion of the local raw water line L12 before branching. The raw water valve V1 is composed of, for example, an electric valve, and is configured to open and close the local raw water line L12 under the control of the local control unit 22.

  The plurality of membrane modules 21 are connected in parallel so as to increase the amount of treated water in order to cope with the required load of the treated water W6 required by the treated water use facility 18 (see FIG. 1).

  The membrane module 21 is supplied with raw water W1. The membrane module 21 produces the permeated water W2 from which contaminants have been removed from the raw water W1 pumped by the raw water pump 3. The membrane module 21 accommodates, for example, a bundle of hollow fiber membranes made of polyvinylidene fluoride (PVDF) in a vessel, and a sealant is filled between the inner peripheral surface of the vessel and the outer peripheral surface of the hollow fiber membrane at both ends of the vessel. Formed. The membrane module 21 can be either an external pressure type or an internal pressure type, but is preferably an external pressure type in which the inside of the hollow fiber is difficult to block. Moreover, as a filtration system, any of a whole quantity filtration system or a cross flow filtration system may be sufficient. In general, the total amount filtration method consumes less energy during the filtration operation, but the growth of the cake layer is fast. Therefore, it is necessary to shorten the interval of backwashing and the interval of forward washing (flushing). On the other hand, the cross flow filtration method consumes a lot of energy due to water circulation during the filtration operation, but because the growth of the cake layer is gradual, it is possible to extend the interval between backwashing and forwardwashing. .

  As the hollow fiber membrane incorporated in the membrane module 21, a membrane having coarser pores than a reverse osmosis membrane (also referred to as “RO membrane”) is used. As the membrane module, a UF membrane module having an ultrafiltration membrane, an MF membrane module having a microfiltration membrane, or the like can be applied. In the present embodiment, the following configuration and operation of the membrane module 21 will be described assuming that the membrane module 21 is an external pressure UF membrane module of a total filtration method.

  A cleaning air supply line L5 is connected to each downstream portion of the local raw water line L12 after branching. The cleaning air supply line L5 is a line that supplies air A1 to the membrane module 21 via the local raw water line L12. The upstream end of the cleaning air supply line L5 is connected to an air compressor (not shown). The downstream end of the cleaning air supply line L5 is branched and connected to the downstream branched portion of the local raw water line L12. An air flow rate adjustment valve V5 is provided in the upstream portion of the cleaning air supply line L5 before branching. The air flow rate adjustment valve V5 is formed of, for example, an electromagnetic valve, and is configured to open and close so as to adjust the amount of air A1 flowing through the cleaning air supply line L5 under the control of the local control unit 22.

  The local permeate water line L22 is a line through which the permeate water W2 produced in the plurality of membrane modules 21 is circulated to the treated water use facility 18 via the permeate water line L21 and the treated water tank 16 (see FIG. 1). . The permeated water line L <b> 21 is a line that connects the membrane module 21 and the treated water tank 16. The upstream end of the permeate line L21 is branched into a plurality of local permeate lines L22, which are connected to the membrane module 21, respectively. The downstream end of the permeate line L21 is connected to the treated water tank 16 (see FIG. 1). As shown in FIG. 4, the local permeate line L22 has a plurality of membrane modules 21, a connection part J1, a connection part J2, a connection part J3, and a permeate valve V2 in order from the upstream side in the membrane filtration device 20. As shown in FIG. 1, a connecting portion J4 is provided between the membrane filtration device 20 and the treated water tank 16 in the permeate line L21.

  As shown in FIG. 4, the temperature sensor 11 is connected to the local permeated water line L22 in the connection part J1. The connection portion J1 is disposed between the plurality of membrane modules 21 and the connection portion J3. The temperature sensor 11 is electrically connected to the local control unit 22. The temperature (detected temperature value) of the permeate water W2 detected by the temperature sensor 11 is transmitted to the local control unit 22 as a detection signal.

  In the connection portion J2, the flow rate sensor 12 is connected to the local permeated water line L22. The flow rate sensor 12 is a device that detects the flow rate of the permeated water W2 flowing through the local permeated water line L22 in the filtration step described later. The flow rate sensor 12 is a device that detects the flow rate of the backwash water W3 flowing through the local permeate water line L22 in the backwash process described later. The connection portion J2 is disposed between the plurality of membrane modules 21 and the connection portion J3. The flow sensor 12 is electrically connected to the local control unit 22. The flow rate (detected flow rate value) of the permeate water W2 or the backwash water W3 detected by the flow rate sensor 12 is transmitted to the local control unit 22 as a detection signal.

  The downstream end portion of the backwash water line L3 is connected to the connection portion J3. The backwash water line L3 is provided with a backwash water valve V3 and a connection portion J3 in order from the upstream side inside the membrane filtration device 20.

  The first discharge line L4 is a line through which the backwash waste water W4 generated in the backwash process or the air A2 generated in the bubbling process (described later) circulates. In the first discharge line L4, the backwash waste water W4 generated in the backwash process or the air A2 generated in the bubbling process is circulated so as to be discharged out of the system. The upstream end of the first discharge line L4 is branched and connected to the membrane module 21, respectively. A first discharge valve V4 is provided in the downstream merged portion of the first discharge line L4. The first discharge valve V4 is composed of, for example, an electromagnetic valve, and is configured to open and close the first discharge line L4 under the control of the local control unit 22.

  The 2nd discharge line L6 is a line which discharges the pollutant removed from the hollow fiber membrane outside the system in the backwashing process and the bubbling process. Through the second discharge line L6, the waste water W5 containing suspended substances is circulated so as to be discharged out of the system. The upstream end of the second discharge line L6 is branched and connected to the membrane module 21 respectively. The second discharge line L6 discharges the waste water W5 containing the suspended matter out of the system. A second discharge valve V6 is provided in the middle of the second discharge line L6. The second discharge valve V6 is composed of, for example, an electromagnetic valve, and is configured to open and close the second discharge line L6 under the control of the local control unit 22.

The membrane filtration device 20 switches between each valve (raw water valve V1, permeate water valve V2, backwash water valve V3, first discharge valve V4, air flow rate adjustment valve V5 and second discharge valve V6), The filtration step, the backwashing step, the bubbling step, and the draining step can be performed. For example, during normal operation, a 30-minute filtration step and a 5-minute other step (back washing step, bubbling step, draining step, and water filling step) are alternately performed. When the membrane filtration device 20 continues filtration at a constant flow rate for a certain time, a cake layer (deposition layer of contaminants) grows outside the hollow fiber membrane, thereby increasing the transmembrane pressure difference. Therefore, after continuing the filtration process for a certain time, the process moves to the back washing process, the bubbling process and the drainage process, the process of discharging the cake layer outside the hollow fiber membrane out of the system and restoring the water flow resistance To be implemented. Thereafter, a water filling step is performed in preparation for the filtration step.
Below, a water filling process, a filtration process, a backwash process, a bubbling process, and a drainage process are demonstrated concretely.

  The water filling process is a process of supplying the raw water W1 to the inside of the membrane module 21 and filling the inside of the membrane module 21 with the raw water W1. Specifically, as shown in FIG. 5, the permeate water valve V2, the backwash water valve V3, the air flow rate adjustment valve V5, and the second discharge valve V6 are closed, and the raw water valve V1 and the first discharge valve V4 are opened. Then, the raw water pump 3 is driven to operate to supply the raw water W1 into the membrane module 21.

  The filtration step supplies raw water W1 to the inside of the membrane module 21, passes the raw water from the outside to the inside of the hollow fiber membrane of the membrane module 21, and manufactures the permeated water W2 from the raw water W1, that is, a filtration treatment. It is a process to be performed. Specifically, as shown in FIG. 5, in the filtration step, the backwash valve V3, the first discharge valve V4, the air flow rate adjustment valve V5, and the second discharge valve V6 are closed, and the raw water valve V1 and the permeate water are closed. The valve V2 is opened, the raw water pump 3 is driven, and the raw water W1 is operated to be pumped to the membrane module 21.

  In the backwashing process, the backwash water W3 (permeate water W2) is supplied to the membrane module 21 by the backwash water pump 5, and the backwash water W3 is circulated from the inside to the outside of the hollow fiber membrane of the membrane module 21. This is a process, that is, a process of performing backwashing. In the back washing process, the pollutant adhered to the membrane surface of the membrane module is washed away. Specifically, as shown in FIG. 5, in the backwashing step, the raw water valve V1, the permeate water valve V2, the air flow rate adjustment valve V5, and the second discharge valve V6 are closed, and the backwash water valve V3 and the first water washing valve V1. The drain valve V4 is opened, the backwash water pump 5 is driven, and the backwash water W3 is operated to be pumped to the membrane module 21. Thereby, the cake layer grown on the outer surface of the hollow fiber membrane is peeled off. The backwash waste water W4 after washing is discharged out of the system through the first discharge line L4.

  In the backwashing process, the chemical addition device 8 is backwashed water W3 in proportion to the flow rate of the backwashing water W3 flowing through the backwashing water line L3, for example, once for a plurality of backwashing processes. To supply drugs. The addition of the drug by the drug adding device 8 is executed at a frequency of about once a day, for example.

  The bubbling step is a step of supplying air A1 from the lower part of the membrane module 21 to swing the bundle of hollow fiber membranes. Thereby, in the membrane module 21 after the back washing process, the contaminants remaining in the gaps between the hollow fiber membranes and the surface of the membrane are removed. Specifically, as shown in FIG. 5, in the bubbling process, the raw water valve V1, the permeate water valve V2, the backwash water valve V3, and the second discharge valve V6 are closed, and the first discharge valve V4 and the air flow rate adjustment valve are closed. It is operated to open V5.

  In the drainage process, the pollutant removed from the hollow fiber membrane in the backwashing process and bubbling process is treated as backwashing drainage W4, air A2, and drainage W5 via the first discharge valve V4 and the second discharge valve V6. To discharge. Specifically, as shown in FIG. 5, in the drainage process, the raw water valve V1, the permeate water valve V2, the backwash water valve V3, and the air flow rate adjustment valve V5 are closed, and the first discharge valve V4 and the second discharge valve. It is operated to open V6.

  Next, the local control unit 22 will be described. The local control unit 22 is configured by a microprocessor (not shown) including a CPU and a memory. In the local control unit 22, the CPU of the microprocessor executes various controls described later according to a predetermined program read from the memory. In the local control unit 22, data and various programs for controlling the membrane filtration device 20 are stored in the memory of the microprocessor. Further, the microprocessor of the local control unit 22 incorporates an integrated timer unit (hereinafter also referred to as “ITU”) that manages time measurement and the like.

  The local control unit 22 calculates the drive frequency of the raw water pump 3 and outputs a frequency designation signal (current value signal or voltage value signal) corresponding to the calculated value of the drive frequency to the first inverter 4.

The local control unit 22 changes the water flow rate of the permeated water W2 produced by the membrane filtration device 20 according to the required load. Specifically, the local control unit 22 inputs a frequency designation signal to the first inverter 4 based on the number control signal transmitted from the number control device 30 via the signal line 52, so that the raw water pump 3 The flow rate of the permeate W2 produced by the membrane filtration device 20 is controlled by controlling the rotation speed.
Further, the local control unit 22 transmits a signal used in the number control device 30 to the number control device 30 via the signal line 52. Examples of the signal used in the number control device 30 include an actual water flow state of the membrane filtration device 20 and other data.

  The local control unit 22 is electrically connected to the raw water valve V1, the permeated water valve V2, the backwash water valve V3, the first discharge valve V4, the air flow rate adjustment valve V5, the second discharge valve V6, the temperature sensor 11, and the flow rate sensor 12. Connected.

  The local control unit 22 performs raw water valve V1, permeate water valve V2, backwash water valve V3 as flow path switching means so as to sequentially perform a water filling process, a filtration process, a backwash process, a bubbling process, and a drainage process. The first discharge valve V4, the air flow rate adjustment valve V5, and the second discharge valve V6 are controlled.

Next, operation | movement of the filtration system 1 of this embodiment is demonstrated, referring FIG.
FIG. 6 is a flowchart showing the operation of the filtration system 1 of the present embodiment.
First, in step ST1, the deviation calculation unit 323 calculates a deviation amount between the required water flow rate and the output water flow rate, and the process proceeds to step ST2.

  In step ST2, the control unit 32 (membrane filtration device selection unit 324) compares the required water flow rate with the output water flow rate. As a result of the comparison by the control unit 32, when the required water flow rate is larger than the output water flow rate, the process proceeds to step ST3. When the required water flow rate is smaller than the output water flow rate, the process proceeds to step ST8. If the required water flow rate and the output water flow rate are equal, the process returns to step ST1.

  In step ST3, the membrane filtration device selection unit 324 selects the membrane filtration device with the lowest load factor, and the process proceeds to step ST4.

  In step ST4, the membrane filtration device selection unit 324 determines whether there are a plurality of membrane filtration devices selected in step ST3. If it is determined that there are a plurality of selected membrane filtration devices, the process proceeds to step ST5. If it is determined that there are not a plurality of selected membrane filtration devices (one unit), the process proceeds to step ST6.

  In step ST5, the membrane filtration device selection unit 324 selects a membrane filtration device having the highest priority among the membrane filtration devices selected in step ST3, and the process proceeds to step ST6.

  In step ST6, the determination unit 325 determines whether the deviation amount is equal to or greater than the unit water flow rate. When it is determined that the deviation amount is equal to or greater than the unit water flow rate, the process proceeds to step ST7. When it is determined that the deviation amount is less than the unit water flow rate, the process ends.

  In step ST7, the output control unit 326 increases the water flow rate of the selected membrane filtration device by the unit water flow rate, and the process returns to step ST1.

  On the other hand, when the required water flow rate is smaller than the output water flow rate as a result of the comparison by the control unit 32 in step ST2, in step ST8, the membrane filtration device selection unit 324 selects the membrane filtration device having the highest load factor. The process proceeds to step ST9.

  In step ST9, the membrane filtration device selection unit 324 determines whether there are a plurality of membrane filtration devices selected in step ST8. If it is determined that there are a plurality of selected membrane filtration devices, the process proceeds to step ST10. If it is determined that there are not a plurality of selected membrane filtration devices (one unit), the process proceeds to step ST11.

  In step ST10, the membrane filtration device selection unit 324 selects the membrane filtration device 20 having the lowest priority among the membrane filtration devices selected in step ST8, and the process proceeds to step ST11.

  In step ST11, the determination unit 325 determines whether the deviation amount is equal to or greater than the unit water flow rate. When it is determined that the deviation amount is equal to or greater than the unit water flow rate, the process proceeds to step ST12. When it is determined that the deviation amount is less than the unit water flow rate, the process ends.

  In step ST12, the output control unit 326 decreases the water flow rate of the selected membrane filtration device 20 by the unit water flow rate, and the process returns to step ST1.

  When the process returns to step ST1 from step ST7 and step ST12, the deviation calculating unit 323 calculates the deviation amount based on the output water flow rate of the membrane filtration device group 2 after changing the water flow rate. .

  Next, a specific example of the operation of the filtration system 1 of the present invention will be described with reference to FIGS. 6 and 7 to 14. 7-14 is a figure which shows typically the water flow state of the membrane filtration apparatus group 2 which concerns on 1st Embodiment, respectively.

  In the first embodiment, as shown in FIG. 7, the filtration system 1 has a membrane filtration device group 2 including five membrane filtration devices 20 having a rated flow rate of 2000 L / h. The unit water flow rate U is set to 100 L / h. Moreover, the priority of “1” to “5” is assigned to each of the first to fifth units of the membrane filtration device 20.

First, the operation of the filtration system 1 when the necessary water flow rate increases will be described with reference to FIGS.
As shown in FIG. 7, in the state where the output water flow rate is 4800 L / h, when the required water flow rate increases to 5150 L / h, first, the deviation calculating unit 323 first calculates the required water flow rate and the output water flow rate. Deviation amount (350 L / h) is calculated (see step ST1 in FIG. 6).

Next, the membrane filtration device selection unit 324 selects the membrane filtration device 20 that changes the water flow rate. Here, since the required water flow rate is larger than the output water flow rate, the membrane filtration device selection unit 324 selects a membrane filtration device 20 having a low load factor among the five membrane filtration devices 20 as shown in FIG. Select (see steps ST2 and ST3 in FIG. 6). Specifically, among the five membrane filtration devices 20, since the load factor of the No. 4 membrane filtration device 20 and the No. 5 membrane filtration device 20 is low and the same load factor, the membrane filtration device selection The unit 324 selects the No. 4 membrane filtration device 20 and the No. 5 membrane filtration device 20.
Here, since a plurality of the membrane filtration devices 20 are selected by the membrane filtration device selection unit 324, the membrane filtration device selection unit 324, as shown in FIG. Among the membrane filtration devices 20 of the unit No. 4, the membrane filtration device 20 of the fourth unit having a high priority is selected (see step ST5 in FIG. 6).
Next, the determination unit 325 determines whether the deviation amount (350 L / h) is equal to or greater than the unit water flow rate U (100 L / h) (see step ST6 in FIG. 6). Here, since the deviation amount is equal to or greater than the unit water flow rate U, the output control unit 326 sets the water flow rate of the No. 4 membrane filtration device 20 to the unit water flow rate U (100 L) as shown in FIG. / H) Increase (see step ST7 in FIG. 6).

After the water flow rate of the No. 4 membrane filtration device 20 is increased by the output control unit 326, the deviation calculation unit 323 determines the necessary flow rate (5150 L / h) of the membrane filtration device group 2 after the flow rate change. A deviation amount (250 L / h) from the output water flow rate (4900 L / h) is calculated (see step ST1 in FIG. 6).
Next, the membrane filtration device selection unit 324 selects the membrane filtration device 20 that changes the water flow rate. Specifically, as shown in FIG. 9, the membrane filtration device selection unit 324 selects the fifth membrane filtration device 20 that is the membrane filtration device 20 with the lowest load factor among the five membrane filtration devices 20. .

  Next, the determination unit 325 determines whether the deviation amount (250 L / h) is equal to or greater than the unit water flow rate U (100 L / h). Here, since the deviation amount is equal to or greater than the unit water flow rate U, the output control unit 326 sets the water flow rate of the membrane filtration device 20 of Unit 5 to the unit water flow rate U (100 L) as shown in FIG. / H) Increase.

After the water flow rate of the No. 5 membrane filtration device 20 is increased by the output control unit 326, the deviation calculation unit 323 determines the required flow rate (5150 L / h) and the flow rate of the membrane filtration device group 2 after the flow rate change. A deviation amount (150 L / h) from the output water flow rate (5000 L / h) is calculated.
Next, the membrane filtration device selection unit 324 selects the membrane filtration device 20 having a low load factor. Here, since the load factors of the membrane filtration devices 20 of Nos. 1 to 5 are all equal, the membrane filtration device selection unit 324 selects the first membrane filtration device 20 having the highest priority (see FIG. 10). .
Next, the determination unit 325 determines whether the deviation amount (150 L / h) is equal to or greater than the unit water flow rate U (100 L / h). Here, since the deviation amount is equal to or greater than the unit water flow rate U, the output control unit 326 sets the water flow rate of the first unit membrane filtration device 20 to the unit water flow rate U (100 L) as shown in FIG. / H) Increase.

After the water flow rate of the No. 5 membrane filtration device 20 is increased by the output control unit 326, the deviation calculation unit 323 determines the required flow rate (5150 L / h) and the flow rate of the membrane filtration device group 2 after the flow rate change. A deviation amount (50 L / h) from the output water flow rate (5100 L / h) is calculated.
Next, the membrane filtration device selection unit 324 selects the membrane filtration device 20 having a low load factor. Here, since the load factor of the membrane filtration devices 20 of Units 2 to 5 is low and the load factors are all equal, the membrane filtration device selection unit 324 has the highest priority among the four units. The device 20 is selected (see FIG. 11).
In this case, since the determination unit 325 determines that the deviation amount (50 L / h) is not equal to or greater than the unit water flow rate U (100 L / h), the output control unit 326 uses the water flow rate of the membrane filtration device 20 of the second unit. Is not changed, and the control for increasing the output water flow rate is terminated (see step ST6 in FIG. 6).

Next, the operation of the filtration system 1 when the necessary water flow rate is reduced will be described with reference to FIGS. 6 and 12 to 14.
As shown in FIG. 12, when the required water flow rate is reduced to 4850 L / h in the state where the output water flow rate is 5100 L / h, first, the deviation calculating unit 323 first calculates the required water flow rate and the output water flow rate. Deviation amount (250 L / h) is calculated (see step ST1 in FIG. 6).

Next, the membrane filtration device selection unit 324 selects the membrane filtration device 20 that changes the water flow rate. Here, since the required water flow rate is smaller than the output water flow rate, the membrane filtration device selection unit 324 selects the membrane filtration device 20 having a high load factor among the five membrane filtration devices 20 (step of FIG. 6). (See ST2 and step ST8). Specifically, as shown in FIG. 12, since the load factor of the No. 1 membrane filtration device 20 is the highest among the five membrane filtration devices 20, the membrane filtration device selection unit 324 has the No. 1 membrane filtration device. Device 20 is selected.
In this case, since the number of membrane filtration devices 20 selected by the membrane filtration device selection unit 324 is one (see step ST9 in FIG. 6), the determination unit 325 then determines that the deviation amount (250 L / h) is a unit flow rate. It is determined whether the flow rate is U (100 L / h) or more (see step ST11 in FIG. 6). Here, since the deviation amount is equal to or greater than the unit water flow rate U, the output control unit 326 converts the water flow rate of the membrane filtration device 20 of the first unit to the unit water flow rate U (100 L) as shown in FIG. / H) decrease (see step ST12 in FIG. 6).

After the water flow rate of the membrane filtration device 20 of Unit 1 is decreased by the output control unit 326, the deviation calculation unit 323 determines the required flow rate (4850 L / h) of the membrane filtration device group 2 after changing the water flow rate. A deviation amount (150 L / h) from the output water flow rate (5000 L / h) is calculated (see step ST1 in FIG. 6).
Next, the membrane filtration device selection unit 324 selects the membrane filtration device 20 that changes the water flow rate. Here, as shown in FIG. 13, since the load factors of the membrane filtration devices 20 of No. 1 to No. 5 are all equal, the membrane filtration device selection unit 324 selects the No. 5 membrane filtration device 20 of the lowest priority. Select (see step ST8 to step ST10 in FIG. 6).

  Next, the determination unit 325 determines whether the deviation amount (150 L / h) is equal to or greater than the unit water flow rate U (100 L / h) (see step ST11 in FIG. 6). Here, since the deviation amount is equal to or greater than the unit water flow rate U, the output control unit 326 converts the water flow rate of the No. 5 membrane filtration device 20 to the unit water flow rate U (100 L) as shown in FIG. / H) decrease (see step ST12 in FIG. 6).

After the flow rate of the membrane filtration device 20 of No. 5 is reduced by the output control unit 326, the deviation calculation unit 323 determines the required flow rate (4850 L / h) and the membrane filtration device group 2 after changing the flow rate. A deviation amount (50 L / h) from the output water flow rate (4900 L / h) is calculated.
Next, the membrane filtration device selection unit 324 selects the membrane filtration device 20 that changes the water flow rate. Here, since the load factor of the membrane filtration devices 20 of Units 1 to 4 is high and the load factors are all equal, the membrane filtration device selection unit 324 has the lowest priority among the four units. Device 20 is selected.
In this case, since the determination unit 325 determines that the deviation amount (50 L / h) is not equal to or greater than the unit water flow rate U (100 L / h), the output control unit 326 uses the water flow rate of the membrane filtration device 20 of the fourth unit. Is not changed, and the control related to the decrease in the output water flow rate is terminated (see step ST11 in FIG. 6).

In the first embodiment described above, the deviation amount after changing the water flow rate is calculated after changing the water flow rate of the selected membrane filtration device 20, but this is not restrictive. That is, the output control unit 326 stores the information of the selected membrane filtration device 20 in the storage unit 31 without changing the water flow rate of the selected membrane filtration device 20, and then the deviation calculation unit 323 The deviation amount may be calculated based on the output water flow rate changed by the unit water flow rate U. In this case, when the calculated deviation amount is lower than the unit water flow rate, the water flow rate of the selected membrane filtration device 20 is collected in the output control unit 326 based on the information stored in the storage unit 31. May be varied.
In addition, the membrane filtration device selection unit 324 determines the number of membrane filtration devices 20 whose flow rate is changed based on the deviation amount and the unit flow rate U, and then loads and prioritizes the plurality of membrane filtration devices 20. You may select the membrane filtration apparatus 20 which changes water flow volume based on an order | rank.

  According to the filtration system 1 of 1st Embodiment demonstrated above, there exist the following effects.

  (1) A unit water flow rate U was set for each of the plurality of membrane filtration devices 20. And the control part 32 selects the membrane filtration apparatus 20 with a low load factor when the required water flow rate is larger than the output water flow rate, and when the required water flow rate is smaller than the output water flow rate, A membrane filtration device selection unit 324 that selects the high membrane filtration device 20, and an output control unit 326 that varies the water flow rate of the membrane filtration device 20 selected by the membrane filtration device selection unit 324 by the unit water flow rate U. Constructed including. Thereby, when the required water flow rate fluctuates, the water flow rate of the membrane filtration device 20 having the highest or lowest load factor can be varied to adjust the output water flow rate. Therefore, the load factors of the plurality of membrane filtration devices 20 Can be leveled. Therefore, every time the required water flow rate fluctuates, the plurality of membrane filtration devices 20 are made without changing the water flow rates of all of the plurality of membrane filtration devices 20 and making the load factor of the plurality of membrane filtration devices 20 uniform. The load factor can be leveled. As a result, in the filtration system 1, the clogging of the film is difficult to proceed.

  (2) The control unit 32 is configured to include a determination unit 325 that determines whether the deviation amount between the required water flow rate and the output water flow rate is greater than or equal to the unit water flow rate U, and the deviation amount is determined by the determination unit 325. When it was determined that the unit water flow rate U or more, the output control unit 326 was caused to change the water flow rate of the membrane filtration device 20. Thereby, when the deviation amount does not reach the unit water flow rate U, the water flow state of the membrane filtration device 20 is not changed, so that the operation state of the filtration system 1 can be stabilized. Further, since the water flow rate of the membrane filtration device 20 can be finely controlled in unit water flow rate U, the output water flow rate in the filtration system 1 can be adjusted with respect to the required water flow rate. Can be done appropriately.

  (3) When the water flow rate of the selected membrane filtration device 20 is changed in the deviation calculating unit 323, the required water flow rate, the output water flow rate of the membrane filtration device group 2 after the water flow rate change, The amount of deviation was calculated. Thereby, a deviation amount is calculated based on the output water flow rate after changing the water flow rate of the membrane filtration apparatus 20. Therefore, since the flow rate of the membrane filtration device can be changed repeatedly until the deviation amount falls below the unit flow rate U, the load factor of the plurality of membrane filtration devices 20 can be obtained even when the required flow rate varies greatly. Can be leveled.

  (4) When the load factors of the plurality of membrane filtration devices 20 are equal, the membrane filtration device selection unit 324 is selected to select the membrane filtration device 20 having the highest priority or the membrane filtration device 20 having the lowest priority. Thereby, even if the load factors of the plurality of membrane filtration devices 20 are equal, the water flow rate of any one of the membrane filtration devices 20 can be changed, so that the output is appropriately performed according to the fluctuation of the required water flow rate. The water flow rate can be changed.

Next, a specific example of the operation of the filtration system 1 according to the second embodiment of the present invention will be described with reference to FIGS.
The filtration system 1 of the second embodiment is different from the first embodiment in that the membrane filtration device group 2 is configured by a plurality of membrane filtration devices 20 having different rated flow rates and unit water flow rates U.
In the second embodiment, the membrane filtration device group 2 includes, for example, the first membrane filtration device 20 having a rated flow rate of 2000 L / h and a unit flow rate of 100 L / h, and a unit flow rate of 2500 L / h. Is composed of three membrane filtration devices, namely, a No. 2 membrane filtration device 20 with a flow rate of 250 L / h and a No. 3 membrane filtration device 20 with a rated flow rate of 3000 L / and a unit water flow rate of 150 L / h. That is, in the second embodiment, the unit water flow rate U is individually set for each of the plurality of membrane filtration devices 20.
Moreover, the priority of “1” to “3” is assigned to each of the first to third units of the membrane filtration device 20.

Here, the operation of the filtration system 1 when the necessary water flow rate is increased will be described.
As shown in FIG. 15, the flow rate of each of the first membrane filtration device 20 to the third membrane filtration device 20 is 1000 L / h, and the output flow rate of the membrane filtration device group 2 is 3000 L / h. When the required water flow rate increases to 3750 L / h, first, the deviation calculating unit 323 calculates a deviation amount (750 L / h) between the required water flow rate and the output water flow rate.

Next, the membrane filtration device selection unit 324 selects the membrane filtration device 20 that changes the water flow rate. Here, since the required water flow rate is larger than the output water flow rate, the membrane filtration device selection unit 324 selects the membrane filtration device 20 having a low load factor among the three membrane filtration devices 20. Specifically, the membrane filtration device selection unit 324 selects the third membrane filtration device 20 having the lowest load factor among the three membrane filtration devices 20.
Next, the determination unit 325 determines whether the deviation amount (750 L / h) is equal to or greater than the unit water flow rate U (150 L / h) of the membrane filtration device 20 of the No. 3 machine. Here, since the deviation amount is equal to or greater than the unit water flow rate U of the No. 3 membrane filtration device 20, the output control unit 326 uses the unit of the evaporation amount of the No. 3 membrane filtration device 20 as shown in FIG. Increase the water flow rate U (150 L / h).

After the water flow rate of the No. 3 membrane filtration device 20 is increased by the output control unit 326, the deviation calculation unit 323 determines the necessary flow rate (3750 L / h) and the flow rate of the membrane filtration device group 2 after the flow rate change. A deviation amount (600 L / h) from the output water flow rate (3150 L / h) is calculated.
Next, the membrane filtration device selection unit 324 selects the membrane filtration device 20 that changes the water flow rate. Specifically, as shown in FIG. 16, the membrane filtration device selection unit 324 again selects the third membrane filtration device 20 which is the membrane filtration device 20 having the lowest load factor among the three membrane filtration devices 20. To do.

  Next, the determination unit 325 determines whether the deviation amount (600 L / h) is equal to or greater than the unit water flow rate U (150 L / h) of the No. 3 membrane filtration device 20. Here, since the deviation amount is equal to or greater than the unit water flow rate U of the membrane filtration device 20 of the No. 3 unit, the output control unit 326 sets the water flow rate of the membrane filtration device 20 of the No. 3 unit as shown in FIG. Increase the unit water flow rate U (150 L / h).

After the water flow rate of the No. 3 membrane filtration device 20 is increased by the output control unit 326, the deviation calculation unit 323 determines the necessary flow rate (3750 L / h) and the flow rate of the membrane filtration device group 2 after the flow rate change. A deviation amount (450 L / h) from the output water flow rate (3300 L / h) is calculated.
Next, the membrane filtration device selection unit 324 selects the membrane filtration device 20 that changes the water flow rate. Here, as shown in FIG. 17, the membrane filtration device selection unit 324 selects the second membrane filtration device 20 that is the membrane filtration device 20 with the lowest load factor among the three membrane filtration devices 20.

  Next, the determination unit 325 determines whether the deviation amount (450 L / h) is equal to or greater than the unit water flow rate U (250 L / h) of the membrane filtration device 20 of the second unit. Here, since the deviation amount is equal to or greater than the unit water flow rate U of the membrane filtration device 20 of the second unit, the output control unit 326 sets the water flow rate of the membrane filtration device 20 of the second unit as shown in FIG. Increase the unit water flow rate U (250 L / h).

After the water flow rate of the membrane filtration device 20 of Unit 2 is increased by the output control unit 326, the deviation calculation unit 323 determines the required water flow rate (3750 L / h) and the flow rate of the membrane filtration device group 2 after changing the water flow rate. A deviation amount (200 L / h) from the output water flow rate (3550 L / h) is calculated.
Next, the membrane filtration device selection unit 324 selects the membrane filtration device 20 that changes the water flow rate. Here, among the three membrane filtration devices 20, the membrane filtration device 20 of No. 3 which is the membrane filtration device 20 with the lowest load factor is selected.

  Next, the determination unit 325 determines whether the deviation amount (200 L / h) is equal to or greater than the unit water flow rate U (150 L / h) of the No. 3 membrane filtration device 20. Here, since the deviation amount is equal to or greater than the unit water flow rate U of the membrane filtration device 20 of the No. 3 unit, the output control unit 326 sets the water flow rate of the membrane filtration device 20 of the No. 3 unit as shown in FIG. Increase the unit water flow rate U (150 L / h).

After the water flow rate of the No. 3 membrane filtration device 20 is increased by the output control unit 326, the deviation calculation unit 323 determines the necessary flow rate (3750 L / h) and the flow rate of the membrane filtration device group 2 after the flow rate change. A deviation amount (50 L / h) from the output water flow rate (3700 L / h) is calculated.
Next, the membrane filtration device selection unit 324 selects the membrane filtration device 20 that changes the water flow rate. Here, as shown in FIG. 19, the membrane filtration device selection unit 324 selects the third membrane filtration device 20 which is the membrane filtration device 20 with the lowest load factor among the three membrane filtration devices 20.

  Next, the determination unit 325 determines whether the deviation amount (50 L / h) is equal to or greater than the unit water flow rate U (150 L / h) of the membrane filtration device 20 of the No. 3 machine. Here, since the deviation amount is lower than the unit water flow rate U of the membrane filtration device 20 of the No. 3 machine, the output control unit 326 does not change the water flow rate of the membrane filtration device 20 of the No. 3 machine, and the output flow rate is not changed. The control related to the water flow rate increase is terminated.

  According to the filtration system 1 of 2nd Embodiment demonstrated above, there exist the following effects besides having the effect of (1)-(4) mentioned above.

  (5) The unit water flow rate U is individually set for each of the plurality of membrane filtration devices 20, and the determination unit 325 is caused to determine whether the unit water flow rate U is greater than or equal to the unit water flow rate U of the selected membrane filtration device 20. . Thereby, when the membrane filtration device group 2 is configured by a plurality of membrane filtration devices 20 having different rated flow rates, different unit water flow rates U can be set according to the rated flow rates of the respective membrane filtration devices 20. In addition, since the determination unit 325 determines whether the deviation amount is equal to or greater than the unit water flow rate U of the selected membrane filtration device 20, the plurality of membrane filtration devices 20 having different unit water flow rates U are used as the membrane filtration device. Even when the group 2 is configured, the output water flow rate in the filtration system 1 can be adjusted appropriately.

  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, the filtration system 1 according to this embodiment includes five filtration devices 20. Not only this but the filtration apparatus of the filtration system 1 should just be at least 2 units | sets. Moreover, it is good also as a structure which provided 6 or more of filtration apparatuses of the filtration system 1. FIG.

  In the filtration system 1 according to the present embodiment, each of the plurality of filtration devices 20 includes four membrane modules 21. Not only this but in the filtration system 1, the some membrane filtration apparatus 20 may be a structure provided with 1 to 3, or 5 or more membrane modules, respectively.

  In the filtration system 1 according to the present embodiment, the amount of the permeated water W2 consumed in the treated water use facility 18 is detected by the water level sensor 17 provided in the treated water tank 16. Not only this but in the filtration system 1, you may comprise so that the water quantity of the permeated water W2 consumed with the treated water use equipment 18 may be detected with the flow sensor provided in the water distribution line L7.

  In the filtration system 1 according to the present embodiment, the treated water tank 16 and the backwash water tank 7 are provided separately. However, the present invention is not limited to this, and the treated water tank 16 and the backwash water tank 7 are shared. You may comprise as one tank to do.

DESCRIPTION OF SYMBOLS 1 Filtration system 2 Membrane filtration apparatus group (filtration apparatus group)
20 Membrane filtration device (filtration device)
32 control unit 324 membrane filtration device selection unit (filtration device selection unit)
325 Determination unit 326 Output control unit U Unit water flow rate W1 Raw water (treated water)
W2 permeate

Claims (4)

A filtration device group comprising a plurality of filtration devices capable of producing permeated water from the treated water by continuously changing the load factor, and the filtration device group according to a required load which is a required flow rate of the permeated water A control unit for controlling the flow rate of the permeated water produced by the filtration system,
In the plurality of filtration devices, a unit water flow rate that is a unit of a variable water flow rate is set,
The controller is
A deviation calculating unit that calculates a deviation amount between a required water flow rate required according to the required load and an output water flow rate output by the filtration device group;
When the required water flow rate is larger than the output water flow rate, a filtration device with a low load factor is selected from the plurality of filter devices, and when the required water flow rate is smaller than the output water flow rate, the A filtration device selection unit for selecting a filtration device with a high load factor among a plurality of filtration devices;
When the required flow rate is larger than the output flow rate, the flow rate of the filtration device selected by the filtration device selection unit is increased by the unit flow rate, and the required flow rate is the output flow rate. An output control unit that decreases the flow rate of the filtration device selected by the filtration device selection unit when the flow rate is smaller than the unit flow rate,
A determination unit that determines whether the deviation amount calculated by the deviation calculation unit is greater than or equal to the unit water flow rate ,
The output control unit changes the flow rate of the filtration device selected by the filtration device selection unit when the determination unit determines that the deviation amount is equal to or greater than the unit flow rate,
When the flow rate of the selected filtration device is changed by the output control unit, the deviation calculation unit calculates the required flow rate and the output flow rate of the filtration device group after the change of the flow rate. filtration system that calculates a deviation amount. The unit water flow rate is individually set for each of the plurality of filtration devices,
The determination unit, a filtration system according to claim 1 determines whether the deviation amount is the filtration apparatus selecting section by more than the unit through the water flow of the selected filtering device. Priorities are set for the plurality of filtration devices,
The filtration device selection unit, when the load factor of the plurality of filtration devices is equal,
When the required water flow rate is larger than the output water flow rate, the highest priority filtration device is selected,
The filtration system according to claim 1 or 2 , wherein a filtration device having the lowest priority is selected when the required water flow rate is smaller than the output water flow rate. The filtration system according to any one of claims 1 to 3 , wherein the unit water flow rate is set to 1% to 5% of a rated flow rate of the filtration device.

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