JP5838642B2 - Water treatment system - Google Patents

Description

  The present invention relates to a water treatment system including a pretreatment unit and a membrane separation unit.

  In the semiconductor manufacturing process, the cleaning of electronic parts and medical instruments, etc., high-purity pure water containing no impurities is used. This type of pure water is generally prepared by pre-treating raw water such as groundwater or tap water with a pretreatment unit such as a filtration device or a water softening device, and then a reverse osmosis membrane module (hereinafter also referred to as “RO membrane module”). It is manufactured by reverse osmosis membrane separation treatment.

  A reverse osmosis membrane made of a polymer material has a characteristic that the water permeability coefficient changes with temperature. Specifically, the water permeability coefficient of the RO membrane module decreases as the temperature of pretreated water (hereinafter also referred to as “pretreated water”) decreases, and increases as the temperature of the pretreated water increases.

  When the pressure pump that pumps the pretreatment water to the RO membrane module is operated at a constant operating pressure, the permeated water (pure water) produced with respect to the required production water volume when the temperature of the pretreatment water becomes lower than the reference temperature. The amount of water is reduced. In this case, the supply amount to the demand point is insufficient. Further, when the temperature of the pretreatment water becomes higher than the reference temperature, the amount of permeated water increases with respect to the required amount of production water. In this case, it leads to the early capacity | capacitance fall of a pre-processing unit and the overconcentration on the primary side membrane surface of RO membrane module.

  Therefore, a water quality reforming system that performs flow rate feedback control has been proposed in order to keep the flow rate of permeated water in the RO membrane module constant regardless of the temperature of the pretreatment water. In this flow rate feedback control, the drive frequency of the pressurizing pump that sends the pretreated water to the RO membrane module is controlled by an inverter so that the flow rate of the permeated water produced by the RO membrane module becomes a target value (Patent Literature). 1).

JP 2005-296945 A

  In the above-described pretreatment unit, for example, when suspended substances accumulate in the filter medium bed, the water flow resistance increases. In the pretreatment unit, when the water flow resistance increases, the pressure of the pretreatment water supplied to the primary side of the pressure pump decreases. Therefore, conventionally, the operating pressure of the raw water pump that supplies the raw water to the pretreatment unit has been set to be high in anticipation of a decrease in the pressure of the pretreatment water sent from the pretreatment unit.

  On the other hand, in the water quality reforming system described in Patent Document 1, the concentrated water produced by the RO membrane module flows out from the concentrated water line connected to the primary outlet port of the RO membrane module. The concentrated water line is connected to a concentrated water circulation line for returning a part of the concentrated water to the pretreatment water line upstream of the pressure pump, and a concentrated water draining line for discharging the remainder of the concentrated water out of the system. Yes.

  In order to distribute the concentrated water through the concentrated water circulation line, a pressure difference is required between the primary side (the concentrated water line side) and the secondary side (the pretreatment water line side) of the concentrated water circulation line. In particular, when a constant flow valve is provided in the concentrated water circulation line, a predetermined pressure difference is required to operate the constant flow valve. For this reason, conventionally, a pressure reducing valve is provided in the pretreatment water line upstream of the position where the concentrated water circulation line joins, and the pressure of the pretreatment water is lowered on the secondary side of the concentrated water circulation line.

  As described above, in the conventional water treatment system, the operating pressure of the raw water pump provided on the upstream side of the pretreatment unit is set to a pressure which is originally necessary, even though the pretreatment water is decompressed on the downstream side of the pretreatment unit. Was set higher than. For this reason, suppression of power consumption in the raw water pump has been an issue.

  Therefore, an object of this invention is to provide the water treatment system which can suppress the power consumption of a raw | natural water pump.

The present invention includes a pretreatment unit that produces pretreatment water from raw water, and a membrane separation unit that produces permeate from pretreatment water, wherein the pretreatment unit is at least one pretreatment to which raw water is supplied. A unit, a raw water pump that is driven at a rotational speed corresponding to the input first driving frequency and supplies raw water to the pretreatment unit, and a first driving frequency corresponding to the input first calculation value signal Is output to the raw water pump, pressure detecting means for detecting the pressure of pretreated water, and the PID algorithm so that the detected pressure value of the pressure detecting means becomes a preset target pressure value. It calculates a first driving frequency of the raw water pump, comprising: a first control unit for outputting the first calculation value signal corresponding to the calculated value of the first drive frequency to the first inverter, wherein the membrane separation unit Is supplied A reverse osmosis membrane module that separates the pretreated water into permeated water and concentrated water, and is driven at a rotational speed corresponding to the input second drive frequency, and supplies the pretreated water toward the reverse osmosis membrane module. A pressure pump; a second inverter that outputs a second drive frequency corresponding to the input second operation value signal to the pressure pump; a flow rate detection means for detecting a flow rate of permeated water; and the flow rate detection means. as detected flow value is a preset target flow rate value, calculates a second driving frequency of the pressure pump by the PID algorithm, the second calculation value corresponding to the calculated value of the second driving frequency A water treatment system comprising: a second control unit that outputs a signal to the second inverter, wherein the water treatment system is manufactured by a raw water line that supplies raw water to the pretreatment unit, and the pretreatment unit. Pretreatment water line for supplying the pretreated water to the reverse osmosis membrane module, a permeate line for sending permeate from the reverse osmosis membrane module, and a concentrate water line for sending concentrated water from the reverse osmosis membrane module And the upstream side is connected to the concentrated water line and the downstream side is connected to the pretreated water line, and a part of the concentrated water flowing through the concentrated water line is upstream of the pressurizing pump in the pretreated water line. A concentrated water circulation line that recirculates to the side, and a concentrated water drain line that discharges the remaining portion of the concentrated water flowing through the concentrated water line to the outside of the apparatus, and the pressure detection means is configured to circulate the concentrated water in the pretreatment water line. The present invention relates to a water treatment system that detects the pressure of pretreatment water that circulates upstream from a line connection position .

  The pretreatment unit includes an information transmission unit that transmits information to the outside, and the first control unit outputs the first driving frequency from the first inverter to the raw water pump. When the detected pressure value is outside the pressure range corresponding to the preset first driving frequency, it is preferable to transmit the information indicating abnormality to the outside by controlling the information transmission unit.

  ADVANTAGE OF THE INVENTION According to this invention, the water treatment system which can suppress the power consumption of a raw | natural water pump can be provided.

1 is an overall configuration diagram of a water treatment system 1 according to an embodiment. It is a flowchart which shows the process sequence in case the 1st control part 17 performs pressure feedback control. It is a flowchart which shows the process sequence in case the 2nd control part 29 performs flow volume feedback control.

  Hereinafter, a water treatment system according to the present invention will be described with reference to the drawings. The water treatment system 1 of the present embodiment is applied to, for example, a pure water production system that produces pure water from fresh water. FIG. 1 is an overall configuration diagram of a water treatment system 1 according to the present embodiment. FIG. 2 is a flowchart showing a processing procedure when the first control unit 17 executes pressure feedback control. FIG. 3 is a flowchart showing a processing procedure when the second control unit 29 executes the flow rate feedback control.

  As shown in FIG. 1, the water treatment system 1 according to this embodiment includes a pretreatment unit 10 and a membrane separation unit 20. The pretreatment unit 10 is a facility for producing the pretreatment water W2 from the raw water W1. The membrane separation unit 20 is a facility for producing the permeated water W3 and the concentrated water W4 from the pretreated water W2.

  The water treatment system 1 includes a raw water line L1, a pretreatment water line L2, a permeate water line L3, a concentrated water line L4, a concentrated water circulation line L5, a concentrated water drainage line (first concentrated water drainage line L6). , A second concentrated water drainage line L7 and a third concentrated water drainage line L8). 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. Moreover, in FIG. 1, the path | route of an electrical connection is shown with a broken line.

First, the configuration of the preprocessing unit 10 will be described.
The pretreatment unit 10 includes a raw water pump 11, a first inverter 12, an activated carbon filtration device 13, a hard water softening device 14, and a prefilter device 15. The preprocessing unit 10 includes a pressure sensor 16 as a pressure detection unit, a first control unit 17, and an alarm unit 18 as an information transmission unit. Among these, the activated carbon filtration device 13, the water softening device 14, and the prefilter device 15 each function as a pretreatment unit.

  The upstream end of the raw water line L1 is connected to a supply source (not shown) of the raw water W1. On the other hand, the downstream end of the raw water line L <b> 1 is connected to the activated carbon filtration device 13.

  The raw water pump 11 is a device that sucks raw water W1 such as tap water or groundwater supplied from a supply source and discharges the raw water W1 toward the activated carbon filtration device 13. The raw water pump 11 is provided in the raw water line L1. The raw water pump 11 is electrically connected to a first inverter 12 (described later). The raw water pump 11 is supplied with driving power whose frequency is converted from the first inverter 12. The raw water pump 11 is driven at a rotational speed corresponding to the input drive frequency.

  The first inverter 12 is an electric circuit that supplies driving power whose frequency is converted to the raw water pump 11. The first inverter 12 is electrically connected to the first control unit 17. A current value signal is input from the first control unit 17 to the first inverter 12. The first inverter 12 outputs a drive frequency corresponding to the input current value signal to the raw water pump 11.

The pretreatment unit group including the activated carbon filtration device 13, the hard water softening device 14, and the prefilter device 15 is a facility for producing the pretreatment water W2 from the raw water W1.
The activated carbon filter 13 removes residual chlorine contained in the raw water W1 in a filter medium bed made of granular activated carbon.
The water softening device 14 substitutes sodium ions (or potassium ions) for hardness components (calcium ions and magnesium ions) contained in the raw water W1 in a cation exchange resin bed (not shown).
The pre-filter device 15 collects fine suspended substances that cannot be removed by the activated carbon filtration device 13 and the water softening device 14 with a wind filter or the like.

  The pressure sensor 16 is a device that detects the pressure of the pretreated water W <b> 2 on the downstream side of the prefilter device 15. The pressure sensor 16 is connected to the pretreatment water line L2 at the connection portion J1. The pressure sensor 16 is electrically connected to the first control unit 17. The pressure of the pretreated water W2 detected by the pressure sensor 16 (hereinafter also referred to as “detected pressure value”) is transmitted to the first control unit 17 as a detection signal.

  The first control unit 17 is configured by a microprocessor (not shown) including a CPU and a memory. The first control unit 17 calculates a first drive frequency for driving the raw water pump 11 so that the detected pressure value of the pressure sensor 16 becomes a preset target pressure value, and calculates the first drive frequency. A current value signal corresponding to the value is output to the first inverter 12 (hereinafter also referred to as “pressure feedback control”). The pressure feedback control by the first control unit 17 will be described later.

  Moreover, when the 1st control part 17 outputs the 1st drive frequency to the raw | natural water pump 11 from the 1st inverter 12, the detected pressure value of the pressure sensor 16 corresponds to the preset 1st drive frequency. If it is off, alarm unit 18 (described later) is controlled to generate an alarm sound.

  The alarm unit 18 is a facility for notifying a system administrator of an abnormality by an alarm sound. The alarm unit 18 is electrically connected to the first control unit 17. The alarm unit 18 generates an alarm sound according to the alarm control signal transmitted from the first control unit 17.

  Here, the pressure feedback control by the first control unit 17 of the preprocessing unit 10 will be described with reference to FIG. The process of the flowchart shown in FIG. 2 is repeatedly executed during operation of the water treatment system 1.

  In step ST101 shown in FIG. 2, the first control unit 17 acquires the target pressure value P ′ of the pretreated water W2. The target pressure value P ′ is, for example, a set value that is input to the memory of the first control unit 17 by a system administrator via a user interface (not shown).

  In step ST102, the first controller 17 determines whether or not the time t measured by an internal timer (not shown) has reached 100 ms, which is the control cycle. In step ST102, when the first control unit 17 determines that the time measured by the timer has reached 100 ms (YES), the process proceeds to step ST103. In Step ST102, when the first control unit 17 determines that the time measured by the timer has not reached 100 ms (NO), the process returns to Step ST102.

  In step ST103 (step ST102: YES determination), the first control unit 17 acquires the detected pressure value P of the pretreated water W2 detected by the pressure sensor 16.

In step ST104, the first control unit 17 sets the velocity type digital PID algorithm so that the deviation between the detected pressure value (feedback value) P acquired in step ST103 and the target pressure value P ′ acquired in step ST101 becomes zero. calculating a manipulated variable _{U 1} by. In the velocity type digital PID algorithm, the change amount of the operation amount is calculated every control cycle (100 ms), and this operation amount is determined by adding this to the previous operation amount.

In Step ST105, the first control unit 17 determines the driving frequency F ₁ of the raw water pump 11 based on the operation amount U ₁ , the target pressure value P ′, and the maximum driving frequency of the raw water pump 11 (set value of 50 Hz or 60 Hz). Calculate.
In step ST 106, the first control unit 17 converts the calculated value of the driving frequency _{F 1,} the corresponding current value signal (4 to 20 mA).

  In step ST <b> 107, the first control unit 17 outputs the converted current value signal to the first inverter 12. In step ST107, when the first control unit 17 outputs the current value signal to the first inverter 12, the first inverter 12 converts the driving power converted into the frequency corresponding to the input current value signal to the raw water pump 11. To supply. As a result, the raw water pump 11 is driven at a rotational speed corresponding to the drive frequency input from the first inverter 12.

  In Step ST108, the first control unit 17 determines whether or not the detected pressure value P acquired in Step ST103 is out of a pressure range corresponding to a preset first drive frequency (hereinafter also referred to as “reference pressure range”). Determine whether. In step ST108, when the first control unit 17 determines that the detected pressure value is outside the reference pressure range (YES), the process proceeds to step ST109. In step ST108, when the first control unit 17 determines that the detected pressure value is within the reference pressure range (NO), the process of this flowchart ends (returns to step ST101).

  In step ST109, the first control unit 17 transmits an alarm control signal to the alarm unit 18 to generate an alarm sound. Thereby, the process of this flowchart is complete | finished (it returns to step ST101).

Next, the configuration of the membrane separation unit 20 will be described.
As shown in FIG. 1, the membrane separation unit 20 includes a pressurizing pump 21, a second inverter 22, and an RO membrane module 23 as a reverse osmosis membrane module. The membrane separation unit 20 includes a flow rate sensor 24 as a flow rate detection means, a plurality of drain valves (first drain valve 25, second drain valve 26, and third drain valve 27), a constant flow valve 28, A second control unit 29.

  The pressurizing pump 21 is a device that sucks the pretreated water W2 sent from the pretreatment unit 10 and discharges it toward the RO membrane module 23. The pressure pump 21 is electrically connected to a second inverter 22 (described later). The driving power whose frequency is converted is supplied from the second inverter 22 to the pressurizing pump 21. The pressurizing pump 21 is driven at a rotational speed corresponding to the input driving frequency.

  The second inverter 22 is an electric circuit that supplies driving power whose frequency is converted to the pressure pump 21. The second inverter 22 is electrically connected to the second control unit 29. A current value signal is input from the second control unit 29 to the second inverter 22. The second inverter 22 outputs a driving frequency corresponding to the input current value signal to the pressurizing pump 21.

  The RO membrane module 23 is a facility for subjecting the pretreated water W2 to membrane separation treatment into permeated water W3 from which dissolved salts have been removed and concentrated water W4 from which dissolved salts have been concentrated. The RO membrane module 23 includes a single or a plurality of RO membrane elements (not shown). The RO membrane module 23 performs membrane separation treatment on the pretreated water W2 with these RO membrane elements to produce permeated water W3 and concentrated water W4. The primary side inlet port of the RO membrane module 23 is connected to the downstream side of the pressurizing pump 21 via the pretreatment water line L2.

  An upstream end portion of the permeate line L3 is connected to the secondary port of the RO membrane module 23. The permeated water W3 produced by the RO membrane module 23 is sent as pure water to a demand location or the like via the permeated water line L3. The upstream end of the concentrated water line L4 is connected to the primary outlet port of the RO membrane module 23. The concentrated water W4 manufactured by the RO membrane module 23 is discharged out of the RO membrane module 23 via the concentrated water line L4.

  The concentrated water circulation line L5 is a line for returning a part of the concentrated water W4 discharged from the RO membrane module 23 to the upstream side of the pressurizing pump 21 in the pretreatment water line L2. The upstream end of the concentrated water circulation line L5 is connected to the concentrated water line L4 at the connection portion J3. Further, the downstream end of the concentrated water circulation line L5 is connected to the pretreatment water line L2 at the connection portion J4.

  The concentrated water drainage line (the first concentrated water drainage line L6, the second concentrated water drainage line L7, and the third concentrated water drainage line L8) discharges the remainder of the concentrated water W4 discharged from the RO membrane module 23 to the outside of the system. Line. The upstream ends of the first concentrated water drainage line L6 to the third concentrated water drainage line L8 are connected to the concentrated water line L4 at the connecting portions J5 and J6.

  The flow rate sensor 24 is a device that detects the flow rate of the permeated water W3 flowing through the permeated water line L3. The flow sensor 24 is connected to the permeated water line L3 at the connection portion J2. The flow sensor 24 is electrically connected to the second control unit 29. The flow rate of the permeated water W3 detected by the flow rate sensor 24 (hereinafter also referred to as “detected flow rate value”) is transmitted to the second control unit 29 as a detection signal.

  The first concentrated water drain line L6, the second concentrated water drain line L7, and the third concentrated water drain line L8 are provided with a first drain valve 25, a second drain valve 26, and a third drain valve 27, respectively. The first drain valve 25 to the third drain valve 27 adjust the drain flow rate of the concentrated water W4 by individually opening and closing the first concentrated water drain line L6 to the third concentrated water drain line L8, and the membrane separation unit 20 The recovery rate of the permeated water W3 can be set to a desired value.

  The first drain valve 25 to the third drain valve 27 are electrically connected to the second control unit 29, respectively. The opening and closing of the valve body in the first drain valve 25 to the third drain valve 27 is controlled by a drive signal transmitted from the second control unit 29.

  The constant flow valve 28 is a device for keeping the flow rate of the concentrated water W4 flowing from the concentrated water line L4 to the concentrated water circulation line L5 constant. The constant flow valve 28 is provided in the concentrated water circulation line L5.

  The second control unit 29 is configured by a microprocessor (not shown) including a CPU and a memory. The second control unit 29 calculates a second drive frequency for driving the pressurizing pump 21 so that the detected flow rate value of the flow rate sensor 24 becomes a preset target flow rate value, and the second drive frequency of the second drive frequency is calculated. A current value signal corresponding to the calculated value is output to the second inverter 22 (hereinafter also referred to as “flow rate feedback control”). The flow rate feedback control by the second control unit 29 will be described later.

  Next, flow rate feedback control by the second control unit 29 of the membrane separation unit 20 will be described with reference to FIG. The process of the flowchart shown in FIG. 3 is repeatedly executed during operation of the water treatment system 1.

  In step ST201 shown in FIG. 3, the second control unit 29 acquires the target flow rate value Q ′ of the permeated water W3. The target flow rate value Q ′ is, for example, a set value input to the memory of the second control unit 29 by a system administrator via a user interface (not shown).

  In Step ST202, the second control unit 29 determines whether or not the time t measured by an internal timer (not shown) has reached 100 ms which is the control cycle. In step ST202, when the second control unit 29 determines that the time measured by the timer has reached 100 ms (YES), the process proceeds to step ST203. In step ST202, when the second control unit 29 determines that the time measured by the timer has not reached 100 ms (NO), the process returns to step ST202.

  In step ST203 (step ST202: YES determination), the second control unit 29 acquires the detected flow rate value Q of the permeated water W3 detected by the flow rate sensor 24.

In step ST204, the second control unit 29 sets the velocity type digital PID algorithm so that the deviation between the detected flow rate value (feedback value) Q ′ acquired in step ST203 and the target flow rate value Q acquired in step ST201 becomes zero. calculating a manipulated variable _{U 2} by. In the velocity type digital PID algorithm, the change amount of the operation amount is calculated every control cycle (100 ms), and this operation amount is determined by adding this to the previous operation amount.

In step ST205, the second control unit 29 determines the driving frequency F of the pressurizing pump 21 based on the manipulated variable U ₂ , the target flow rate value Q ′ and the maximum driving frequency of the pressurizing pump 21 (set value of 50 Hz or 60 Hz). ₂ is calculated.
In step ST 206, the second control unit 29 converts the calculated value of the driving frequency _{F 2,} the corresponding current value signal (4 to 20 mA).

  In step ST207, the second control unit 29 outputs the converted current value signal to the second inverter 22. Thereby, the process of this flowchart is complete | finished (it returns to step ST201).

  In step ST207, when the second control unit 29 outputs the current value signal to the second inverter 22, the second inverter 22 applies the driving power converted to the frequency corresponding to the input current value signal to the pressure pump. 21. As a result, the pressurizing pump 21 is driven at a rotation speed corresponding to the driving frequency input from the second inverter 22.

  According to the water treatment system 1 which concerns on this embodiment mentioned above, the following effects are acquired, for example.

  In the water treatment system 1 according to the present embodiment, the first control unit 17 performs pressure feedback control based on the detected pressure value of the pretreated water W2. According to this, in the pretreatment unit 10, even if suspended substances or the like accumulate on the filter medium bed and the water flow resistance increases, the pressure of the pretreatment water W2 can be maintained at a substantially target pressure value. Therefore, in the raw water pump 11 of the pretreatment unit 10, it is not necessary to set a high operating pressure in anticipation of a decrease in the pressure of the pretreatment water W2. Therefore, the power consumption of the raw water pump 11 can be suppressed.

  Further, since the target pressure value of the pretreatment water W2 can be set to a necessary pressure value, the secondary side of the concentrated water circulation line L5 can be provided without providing a pressure reducing valve in the pretreatment water line L2 upstream of the pressurizing pump 21. The pressure of can be adjusted low. Therefore, even when the constant flow valve 28 is provided in the concentrated water circulation line L5, a pressure difference necessary for the operation of the constant flow valve 28 can be ensured.

  Therefore, in the water treatment system 1 according to the present embodiment, it is not necessary to set the operating pressure of the raw water pump 11 higher than the originally required pressure, so that the power consumption of the raw water pump can be suppressed.

  Further, in the water treatment system 1 according to the present embodiment, the first control unit 17 is configured to provide an alarm unit when the detected pressure value of the pressure sensor 16 is outside the pressure range corresponding to the preset first drive frequency. 18 is controlled to generate an alarm sound. Therefore, the system administrator can promptly respond to a failure of the raw water pump 11 or an abnormality of the pretreatment unit.

  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 this embodiment, the structure provided with the activated carbon filtration apparatus 13, the water softening apparatus 14, and the pre filter apparatus 15 as the pre-processing part 10 was demonstrated. However, the present invention is not limited to this, and a configuration provided with another device may be employed. The pretreatment unit 10 may have a configuration including the activated carbon filtration device 13 and the prefilter device 15 or a configuration including the hard water softening device 14 and the prefilter device 15. That is, the preprocessing unit 10 may be configured to include at least the prefilter device 15.

  Moreover, in this embodiment, the structure which provided the 1st drainage valve 25-the 3rd drainage valve 27 in the 1st concentrated water drainage line L6-the 3rd concentrated water drainage line L8 was demonstrated. The configuration is not limited to this, and the concentrated water drainage line may be one without branching, and a proportional control valve may be provided in this line. In that case, the drain flow rate of the concentrated water W4 can be adjusted by transmitting a current value signal (for example, 4 to 20 mA) from the second control unit 29 to the proportional control valve to control the valve opening.

  Further, in the configuration in which the proportional control valve is provided, the flow rate sensor may be provided in the concentrated water drain line. The flow rate value detected by the flow rate sensor is input to the second control unit 29 as a feedback value. Thereby, the waste_water | drain flow volume of the concentrated water W4 can be controlled more correctly.

  Moreover, in this embodiment, the alarm part 18 as an information transmission part demonstrated the example which notifies abnormality to a system administrator by an alarm sound. However, the present invention is not limited to this, and an abnormality may be notified to the system administrator by blinking or lighting of a lamp or the like, or may be notified by voice. Alternatively, a message notifying the abnormality may be displayed on a terminal operated by a system administrator or a monitor on the control panel.

DESCRIPTION OF SYMBOLS 1 Water treatment system 10 Pretreatment part 11 Raw water pump 12 1st inverter 13 Activated carbon filtration apparatus (pretreatment unit)
14 Water softener (Pretreatment unit)
15 Pre-filter device (pre-processing unit)
16 Pressure sensor (pressure detection means)
17 1st control part 18 Alarm part (information transmission part)
20 Membrane Separation Unit 21 Pressure Pump 22 Second Inverter 23 RO Membrane Module (Reverse Osmosis Membrane Module)
24 Flow rate sensor (flow rate detection means)
25 1st drain valve 26 2nd drain valve 27 3rd drain valve 28 Constant flow valve 29 2nd control part L1 Raw water line L2 Pretreatment water line L3 Permeate water line L4 Concentrated water line L5 Concentrated water circulation line L6 1st concentrated water drainage Line L7 Second concentrated water drainage line L8 Third concentrated water drainage line W1 Raw water W2 Pretreatment water W3 Permeated water W4 Concentrated water

Claims (2)

Including a pretreatment unit for producing pretreatment water from raw water, and a membrane separation unit for producing permeate from pretreatment water,
The pretreatment unit includes at least one pretreatment unit to which raw water is supplied;
A raw water pump that is driven at a rotational speed corresponding to the input first driving frequency and supplies raw water to the pretreatment unit;
A first inverter that outputs to the raw water pump a first drive frequency corresponding to the input first operation value signal;
Pressure detecting means for detecting the pressure of the pretreated water;
The first driving frequency of the raw water pump is calculated by a PID algorithm so that the detected pressure value of the pressure detecting means becomes a preset target pressure value, and the first driving frequency corresponding to the calculated value of the first driving frequency is calculated . A first control unit that outputs the calculated value signal to the first inverter,
The membrane separation unit is a reverse osmosis membrane module that separates the supplied pretreatment water into permeate and concentrated water;
A pressure pump that is driven at a rotational speed corresponding to the input second driving frequency and supplies pretreated water toward the reverse osmosis membrane module;
A second inverter that outputs a second drive frequency corresponding to the input second operation value signal to the pressurizing pump;
Flow rate detection means for detecting the flow rate of the permeated water,
The second driving frequency of the pressurizing pump is calculated by a PID algorithm so that the detected flow rate value of the flow rate detecting means becomes a preset target flow rate value, and the second driving frequency corresponding to the calculated value of the second driving frequency is calculated . A water treatment system comprising: a second control unit that outputs a calculated value signal of 2 to the second inverter ,
Water treatment system
A raw water line for supplying raw water to the pretreatment unit;
A pretreatment water line for supplying pretreatment water produced by the pretreatment unit to the reverse osmosis membrane module;
A permeate line for delivering permeate from the reverse osmosis membrane module;
A concentrated water line for delivering concentrated water from the reverse osmosis membrane module;
An upstream side is connected to the concentrated water line and a downstream side is connected to the pretreated water line, and a part of the concentrated water flowing through the concentrated water line is located upstream of the pressurizing pump in the pretreated water line. A concentrated water circulation line to be refluxed;
A concentrated water drainage line for discharging the remainder of the concentrated water flowing through the concentrated water line to the outside of the apparatus,
The water treatment system, wherein the pressure detection means detects the pressure of pretreatment water that circulates upstream of the connection position of the concentrated water circulation line in the pretreatment water line . The pre-processing unit includes an information transmission unit that transmits information to the outside.
When the first control unit outputs the first drive frequency from the first inverter to the raw water pump, the detected pressure value of the pressure detecting means has a pressure range corresponding to a preset first drive frequency. In the case of detachment, the information transmission unit is controlled to transmit information indicating abnormality to the outside.
The water treatment system according to claim 1.

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