JP7180469B2 - Reverse osmosis membrane separator - Google Patents

Description

The present invention relates to a reverse osmosis membrane separation device.

High-purity pure water containing no impurities is used in the manufacturing process of semiconductors, cleaning of electronic parts and medical equipment, and the like. This type of pure water is generally produced by subjecting raw water such as groundwater and tap water to reverse osmosis membrane separation treatment using a reverse osmosis membrane module (hereinafter also referred to as "RO membrane module").

The water permeability coefficient of a reverse osmosis membrane made of polymeric material changes with temperature. The water permeability coefficient of a reverse osmosis membrane also changes due to clogging of pores (hereinafter also referred to as "membrane clogging") and deterioration due to material oxidation (hereinafter also referred to as "membrane deterioration").

Therefore, in order to keep the flow rate of the permeated water in the RO membrane module constant regardless of the temperature of the feed water and the state of the reverse osmosis membrane, a water quality reforming system that performs flow rate feedback water volume control has been proposed (for example, Patent Document 1). In this flow rate feedback water volume control, the drive frequency of the pressure pump is controlled by the inverter so that the flow rate of the permeated water produced by the RO membrane module reaches the target flow rate value.

In the above water quality reforming system, the concentrated water separated by the RO membrane module is delivered from the concentrated water line connected to the primary side outlet port of the RO membrane module. Also, the permeated water separated by the RO membrane module is sent out from the permeated water line connected to the secondary side port of the RO membrane module. The concentrated water line branches into a circulating water line and a concentrated water drain line. The circulating water line is a line that returns part of the concentrated water sent from the concentrated water line to the feed water line upstream of the pressure pump. The concentrated water drain line is a line for discharging the rest of the concentrated water sent from the concentrated water line to the outside of the apparatus. The feed water line is a line that supplies feed water to the RO membrane module via a pressure pump.

By the way, in an RO membrane module using a spiral-type element, a cross-flow separation operation is normally employed in order to prevent clogging of the membrane surface by organic components and suspended solids. In this cross-flow method, a pressurizing pump is used to circulate the feed water at a flow rate that is at least five times the flow rate of the permeated water, and a pressure greater than the osmotic pressure of the feed water is applied to the primary side of the membrane for separation. I do. At this time, in the RO membrane module, the circulation ratio (flow rate of concentrated water/flow rate of permeated water) defined by the ratio of the flow rate of concentrated water to the flow rate of permeated water is preferably adjusted to about "5".

As a reverse osmosis membrane separation device that adjusts the circulation ratio to a predetermined value, Patent Document 2 includes a flow sensor that detects the flow rate of concentrated water flowing through a drainage line, and the detected flow rate of this flow sensor is determined by recovery control. Disclosed is a reverse osmosis membrane separation apparatus that feedback-controls the valve opening of a proportional control drain valve as a drain flow rate adjustment means so as to obtain a calculated value (target drain flow rate) of the drain flow rate.

JP 2005-296945 A JP 2016-203084 A

However, in the reverse osmosis membrane separator according to Patent Literature 2, when a failure occurs in the flow rate sensor that detects the flow rate of concentrated water, the above-described waste water flow rate feedback control cannot be executed. Therefore, in order to maintain the normal recovery rate, it became necessary to stop the reverse osmosis membrane separator.

SUMMARY OF THE INVENTION An object of the present invention is to provide a reverse osmosis membrane separation apparatus capable of performing backup operation at a recovery rate equivalent to that in normal operation without stopping the apparatus even when a waste water flow meter fails.

The present invention comprises a water supply line through which feed water flows, a reverse osmosis membrane module that separates the feed water into permeated water and concentrated water, and an upstream end connected to the feed water line at a confluence portion to transfer the feed water containing the feed water. A feed water line to be supplied to the reverse osmosis membrane module, a permeate line through which the permeate separated by the reverse osmosis membrane module passes, and a concentrated water line through which the concentrated water separated by the reverse osmosis membrane module passes; A concentrated water discharge line connected to the downstream end of the concentrated water line and discharging concentrated water as concentrated water out of the system, and a concentrated water discharged out of the apparatus by adjusting the opening degree substantially steplessly. A wastewater flow rate adjusting valve for adjusting the wastewater flow rate, a pressure measuring means for measuring the primary pressure of the wastewater flow rate adjusting valve, a first flow rate measuring means for measuring the flow rate of permeated water, and a second flow rate measuring means for measuring the wastewater flow rate. flow rate measuring means, failure detection means for detecting a failure of the second flow rate measuring means, and when the second flow rate measuring means fails, from the measured value of the primary pressure of the drainage flow rate adjustment valve and the opening, Wastewater flow rate prediction means for calculating the predicted value of the wastewater flow rate, and the recovery rate calculated from the flow rate of permeated water and the predicted value of the wastewater flow rate is set to the target recovery rate, which is the target value of the recovery rate. It relates to a reverse osmosis membrane separation device provided with opening adjustment means for adjusting the opening.

Further, a circulating water line connected to the downstream end of the concentrated water line and returning the concentrated water to the merging portion as supply water, and a concentrated water flow rate adjusting means for adjusting the flow rate of the concentrated water passing through the concentrated water line. , wherein the pressure measuring means preferably measures the pressure of the water supply passing through the water supply line as the primary pressure of the water discharge flow control valve.

A pressurizing pump provided in the feed water line for sucking feed water and discharging it as feed water toward the reverse osmosis membrane module; and pump control means for controlling the pressure pump.

According to the present invention, backup operation can be performed at a recovery rate equivalent to that in normal operation without stopping the apparatus even when the drainage flow meter fails.

1 is an overall configuration diagram of a reverse osmosis membrane separation device according to an embodiment of the present invention; FIG. It is a figure which shows the relationship of the pressure and flow volume which concern on the flow control unit used by embodiment of this invention. It is a functional block diagram of the control part with which the reverse osmosis membrane separation apparatus which concerns on embodiment of this invention is equipped. 4 is a graph showing the relationship between the Cv value and the degree of opening of the wastewater flow control valve provided in the reverse osmosis membrane separation device according to the embodiment of the present invention. It is a graph which shows the relationship between the recovery rate in the reverse osmosis membrane separator which concerns on embodiment of this invention, and the opening degree of a waste-water-flow-regulating valve. It is a flow chart which shows operation of a reverse osmosis membrane separation device concerning an embodiment of the present invention.

[1 Configuration of reverse osmosis membrane separation device]
A reverse osmosis membrane separation device 1 according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of a reverse osmosis membrane separation device 1 according to the first embodiment. The reverse osmosis membrane separation device 1 according to this embodiment is applied, for example, to a pure water production system that produces pure water from fresh water.

As shown in FIG. 1, the reverse osmosis membrane separation device 1 according to the present embodiment includes a water supply pump 12, a water supply side inverter 13, a pressure pump 2, a pressure side inverter 3, and an RO as a reverse osmosis membrane module. Membrane module 4, flow rate adjusting unit 5, check valve 6, waste water flow rate adjusting valve 7 (proportional control valve) as waste water flow rate adjusting means, pressure sensor P1, first flow rate sensor FM1, second flow rate A sensor FM2 and a control unit 30 are provided. The illustration of electrical connection lines between the control unit 30 and the device to be controlled is omitted.

In addition, the reverse osmosis membrane separation device 1 includes a water supply line L1, a feed water line L2, a permeated water line L3, a first concentrated water line L41, a second concentrated water line L42, a circulating water line L5, and a waste water. and a line L6. The term "line" used herein is a general term for lines through which fluid can flow, such as channels, routes, and pipelines.

The water supply line L1 is a line that supplies the water supply W1 to J2, which is the junction with the supply water line L2. The upstream end of the water supply line L1 is connected to a supply source (not shown) of the water supply W1. The water supply line L1 is provided with a water supply pump 12, a pressure sensor P1, and a junction J2 in this order from the upstream side to the downstream side.

The water supply W1 flowing through the water supply line L1 is not limited to water supplied directly from a supply source (not shown) of the water supply W1. etc.), water softeners and other pretreatment devices.

The water supply pump 12 is a device that sucks the water supply W<b>1 flowing through the water supply line L<b>1 and pumps (discharges) it toward the pressure pump 2 . The water supply pump 12 is supplied with drive power whose frequency has been converted from the water supply side inverter 13 . The water supply pump 12 is driven at a rotational speed corresponding to the frequency of the supplied (input) driving power (hereinafter also referred to as "driving frequency").

The water supply side inverter 13 is an electric circuit (or a device having such a circuit) that supplies the water supply pump 12 with drive power whose frequency has been converted. The water supply side inverter 13 is electrically connected to the controller 30 . A command signal is input to the water supply side inverter 13 from the control unit 30 . The water supply-side inverter 13 outputs to the water supply pump 12 drive power having a drive frequency corresponding to the command signal (current value signal or voltage value signal) input from the control unit 30 .

In this embodiment, the control unit 30 controls the water supply side inverter 13 so that the water supply pump 12 discharges the water supply W1 at a predetermined constant pressure value. The constant pressure value of the water supply W1 applied by the water supply pump 12 is set to a pressure value that allows the water supply W1 flowing through the water supply line L1 to be supplied to the pressure pump 2 . Thereby, the water supply pressure of the water supply W1 becomes a constant pressure value.

The pressure sensor P1 is a device that detects the pressure of the water supply W1 at the junction J2. The pressure of the water supply W1 detected by the pressure sensor P1 (hereinafter also referred to as "first detected pressure value") is transmitted to the control section 30 as a detection signal. In addition, the pressure sensor P1 measures the pressure of the water supply W1 as the primary pressure of the drainage flow rate control valve 7 .

The feed water line L2 is a line that supplies the feed water W1 to the RO membrane module 4 as the feed water W2. The upstream end of the water supply line L2 is connected to the junction J2. The downstream end of the feed water line L2 is connected to the primary side inlet port of the RO membrane module 4 . The water supply line L2 is provided with a junction J2, a pressure pump 2, and an RO membrane module 4 in this order from the upstream side to the downstream side.

The pressure pump 2 is provided in the supply water line L2. The pressurizing pump 2 is a device that sucks the feed water W1 in the feed water line L2 and pumps (discharges) it toward the RO membrane module 4 as the feed water W2. The pressurizing pump 2 is supplied with drive power whose frequency has been converted from the pressurizing inverter 3 . The pressurizing pump 2 is driven at a rotational speed corresponding to the frequency of the supplied (input) driving power (hereinafter also referred to as "driving frequency").

The pressurization-side inverter 3 is an electric circuit (or a device having such a circuit) that supplies the pressurization pump 2 with drive power whose frequency has been converted. The pressure-side inverter 3 is electrically connected to the controller 30 . A command signal is input to the pressure-side inverter 3 from the control unit 30 . The pressurization-side inverter 3 outputs to the pressurization pump 2 drive power having a drive frequency corresponding to the command signal (current value signal or voltage value signal) input from the control unit 30 .

The RO membrane module 4 is equipment for membrane separation treatment of the feed water W2 discharged from the pressure pump 2 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 4 includes single or multiple RO membrane elements (not shown). The RO membrane module 4 membrane-separates the feed water W2 using these RO membrane elements to produce permeated water W3 and concentrated water W4.

The permeated water line L3 is a line through which the permeated water W3 separated by the RO membrane module 4 is delivered. The upstream end of the permeate line L3 is connected to the secondary port of the RO membrane module 4 . A downstream end of the permeated water line L3 is connected to a device or the like at a demand point. A first flow rate sensor FM1 (hereinafter also referred to as "first flow rate detection means") is installed in the permeated water line L3.

The first flow rate sensor FM1 is a device that detects the flow rate of the permeated water W3 flowing through the permeated water line L3 as a first detected flow rate value. The first flow rate sensor FM1 is connected to the permeated water line L3. The first flow rate sensor FM1 is electrically connected to the controller 30 . A first detected flow rate value of the permeated water W3 detected by the first flow rate sensor FM1 is transmitted to the control section 30 as a detection signal. As the first flow rate sensor FM1, for example, a pulse transmission type flow rate sensor in which an axial flow impeller or a tangential impeller (not shown) is arranged in a flow path housing can be used.

The first concentrated water line L41 is a line through which the concentrated water W4 separated by the RO membrane module 4 is delivered. The upstream end of the first concentrated water line L41 is connected to the primary outlet port of the RO membrane module 4 . Also, the downstream side of the first concentrated water line L41 is connected to the primary side of the flow rate adjustment unit 5 .

Also, the second concentrated water line L42 is a line for sending out the concentrated water W4 whose flow rate is adjusted by the flow rate adjustment unit 5 . The upstream end of the second concentrated water line L<b>42 is connected to the secondary side of the flow rate adjustment unit 5 . Further, the downstream side of the second concentrated water line L42 is branched into the circulating water line L5 and the drainage line L6 at the connection J1.

In addition, henceforth, the 1st concentrated water line L41 and the 2nd concentrated water line L42 may be collectively called "concentrated water line L4."

The flow rate adjustment unit 5 has a constant flow rate element that circulates a substantially constant flow of concentrated water regardless of the differential pressure in the flow rate adjustment unit 5, and the concentration is substantially proportional to the differential pressure in the flow rate adjustment unit 5. and a proportional element that increases the flow rate of the water W4. Specifically, the differential pressure in the flow rate adjusting unit 5 is the differential pressure between the water pressure of the first concentrated water line L41 and the water pressure of the second concentrated water line L42. A constant flow element maintains a constant flow value without the need for auxiliary power or external manipulation, and may be used, for example, under the name of a water governor. As the proportional element, for example, an orifice may be used.

FIG. 2 is a graph showing an example of the relationship between the inlet pressure of the RO membrane module 4 and the flow rate of concentrated water flowing through the flow rate adjusting unit 5. As shown in FIG. Since the flow rate adjusting unit 5 is provided with a constant flow rate element, the flow rate of the concentrated water flowing through the flow rate adjusting unit 5 rises to point A at once when the inlet pressure is generated. That is, approximately, the flow rate at the height of point A flows into the flow rate adjusting unit 5 at the same time as the inlet pressure is generated. At the same time, since the flow rate adjusting unit 5 has a proportional element, the flow rate of the concentrated water flowing through the flow rate adjusting unit 5 increases linearly as the inlet pressure rises.

In addition, in the flow rate adjustment unit 5, the constant flow rate element and the proportional element may be configured integrally or may be configured separately. When configured integrally, for example, the flow direction of the proportional element is aligned with the longitudinal direction of the flow rate adjustment unit 5, and the flow direction of the constant flow rate element is orthogonal to the longitudinal direction of the flow rate adjustment unit 5. It may be configured as Alternatively, the flow direction of the proportional element may be perpendicular to the longitudinal direction of the flow rate adjusting unit 5 and the flow direction of the constant flow rate element may be aligned with the longitudinal direction of the flow rate adjusting unit 5 . Alternatively, both the flow direction of the constant flow rate element and the flow direction of the proportional element may be configured to match the longitudinal direction of the flow rate adjustment unit 5 .
Moreover, below, the flow control unit 5 is also called a "concentrated water flow control means."

The circulating water line L5 is a line branched from the concentrated water line L4, and is a line for returning the circulating water W41, which is a part of the concentrated water W4 separated by the RO membrane module 4, to the junction J2. The upstream end of the circulating water line L5 is connected to the concentrated water line L4 at the connection J1. Further, the downstream end of the circulating water line L5 is connected to the water supply line L1 at the junction J2. A check valve 6 is provided in the circulating water line L5.

The drain line L6 is a line that branches off from the concentrated water line L4 at the connection J1 and discharges waste water W42, which is the remainder of the concentrated water W4 separated by the RO membrane module 4, to the outside of the apparatus (outside the system). The drainage line L6 is provided with a second flow rate sensor FM2 and a drainage flow rate adjustment valve 7 as drainage flow rate adjustment means.

The second flow rate sensor FM2 is a device that detects the flow rate of the waste water W42 flowing through the drainage line L6 as a second detected flow rate value. The second flow rate sensor FM2 is electrically connected to the controller 30 . A second detected flow rate value of the waste water W42 detected by the second flow rate sensor FM2 is transmitted to the control section 30 as a pulse signal. As the second flow rate sensor FM2, for example, a pulse transmission type flow rate sensor having an axial flow impeller or a tangential impeller (not shown) arranged in the flow path housing can be used.

The drainage flow rate adjustment valve 7 is a valve capable of adjusting the drainage flow rate of the drainage W42 discharged from the drainage line L6 to the outside of the apparatus. The drainage flow rate adjustment valve 7 is electrically connected to the controller 30 . The valve opening degree of the drainage flow rate adjustment valve 7 is controlled by a drive signal transmitted from the control section 30 . By transmitting a current value signal (eg, 4 to 20 mA) from the control unit 30 to the drainage flow rate adjustment valve 7 to control the valve opening, the drainage flow rate of the drainage W42 can be adjusted.

The control unit 30 has a CPU, a ROM, a RAM, a CMOS memory, etc., which are known to those skilled in the art and are configured to communicate with each other via a bus.

The CPU is a processor that controls the reverse osmosis membrane separation device 1 as a whole. The CPU reads various programs stored in the ROM via the bus, and controls the entire reverse osmosis membrane separation device 1 according to the various programs, thereby performing a failure detection unit 301, a wastewater flow rate prediction unit 302, and a It is configured to realize the functions of the degree adjustment unit 303 and the pump control unit 304 . Various data such as temporary calculation data and display data are stored in the RAM. The CMOS memory is backed up by a battery (not shown) and configured as a non-volatile memory that retains the stored state even when the reverse osmosis membrane separation device 1 is powered off.

FIG. 3 is a functional block diagram of the control section 30. As shown in FIG. The control unit 30 includes a failure detection unit 301 , a drainage flow rate prediction unit 302 , an opening adjustment unit 303 and a pump control unit 304 .

The failure detection unit 301 detects failure of the second flow rate sensor FM2. Here, failure of the second flow rate sensor FM2 includes, for example, a disconnection inside the second flow rate sensor FM2 or between the second flow rate sensor FM2 and the control unit 30. is detected by suddenly becoming 0.

The waste water flow rate prediction unit 302 calculates a predicted value of the waste water flow rate from the measured value of the primary pressure of the waste water flow rate adjustment valve 7 and the opening degree of the waste water flow rate adjustment valve 7 when the second flow rate sensor FM2 fails.

A more detailed calculation method is as follows. That is, when the drainage flow rate adjustment valve 7 is fully opened, the drainage flow rate of the fluid passing through the drainage flow rate adjustment valve 7 per unit time is called the capacity of the drainage flow rate adjustment valve 7 . A numerical value expressed by keeping the specifications of this fluid at a certain standard value is called a capacity coefficient, and an example thereof is a Cv value.
Specifically, the Cv value is defined as Q [gal/mol] for the waste water flow rate, G for the specific gravity of water, and Δp [lbf/in ² ] for the differential pressure before and after the waste water flow rate control valve 7. is a value calculated by the formula (1). If the differential pressure is the same, the larger the Cv value, the larger the flow rate that passes through.
Cv=Q×√(G/Δp) Equation (1)

FIG. 4 is a graph showing an example of the relationship between the Cv value and the opening degree of the drainage flow rate control valve 7, and the relational expression representing this relationship is set in the CPU in advance. The drainage flow rate prediction unit 302 calculates the Cv value from the opening degree of the drainage flow rate adjustment valve 7 using the relational expression shown in the graph of FIG. , the predicted value of the wastewater flow rate is calculated.

The opening adjustment unit 303 calculates the recovery rate from the flow rate of the permeated water W3 detected by the first flow rate sensor FM1 and the predicted value of the waste water flow rate calculated by the waste water flow rate prediction unit 302. This recovery rate is The opening degree of the drainage flow control valve 7 is adjusted so as to achieve the target recovery rate, which is the target value of the recovery rate. Note that the target recovery rate differs depending on the water temperature.

More specifically, when the failure detection unit 301 detects a failure of the drainage flow rate adjustment valve 7, the opening adjustment unit 303 performs backup operation to detect the differential pressure of the drainage flow rate adjustment valve 7 (actually, the pressure sensor After controlling the water supply pressure detected by P1 to a fixed value such as 0.2 MPa, the opening degree of the drainage flow control valve 7 that provides the target recovery rate is calculated, and the opening degree is feedback-controlled.

FIG. 5 is a graph showing the relationship between the recovery rate and the opening degree of the drainage flow control valve 7. As shown in FIG. As shown in FIG. 5, the higher the target recovery rate, the more the opening degree of the drainage flow control valve 7 needs to be lowered.

As described above, the relational expression between the Cv value and the opening degree of the drainage flow rate adjustment valve 7 shown in FIG. After calculating the value, predict the wastewater flow rate using the calculated Cv value, calculate the recovery rate using the predicted wastewater flow rate, and adjust the opening so that the calculated recovery rate is the target recovery rate. It is assumed that the section 303 adjusts the opening degree of the drainage flow rate adjustment valve 7 . Not limited to this, the relational expression between the recovery rate and the opening degree of the drainage flow rate adjustment valve 7 shown in FIG. The degree of opening of the valve 7 may be adjusted.

A pump control unit 304 controls the pressure pump 2 . For example, the pump control unit 304 may feedback-control the pressure pump 2 so that the flow rate of the permeate W3 detected by the first flow rate sensor FM1 becomes a predetermined flow rate target value.

[2 Operation of reverse osmosis membrane separation device]
FIG. 6 is a flow chart showing the operation of the reverse osmosis membrane separation device 1. As shown in FIG.
In step S1, when the failure detection unit 301 detects a failure of the second flow rate sensor FM2 (S1: YES), the process proceeds to step S2. If the failure detection unit 301 does not detect failure of the second flow rate sensor FM2 (S1: NO), the process proceeds to step S1.

In step S2, the opening adjustment unit 303 controls the differential pressure of the waste water flow rate adjustment valve 7 to a fixed value, and then the flow rate of the permeated water W3 detected by the first flow sensor FM1 and the waste water flow rate prediction unit 302 Calculate the recovery rate from the predicted value of the waste water flow rate calculated by the target value of the opening degree of the waste water flow rate adjustment valve 7 so that this recovery rate becomes the target recovery rate, which is the target value of the recovery rate Calculate

In step S3, the opening adjustment unit 303 feedback-controls the opening of the drainage flow rate adjustment valve 7 so as to reach the target value calculated in step S2.
After that, the process moves to step S2 (return).

[3 Effect of Embodiment]
According to the reverse osmosis membrane separation device 1 according to the embodiment described above, for example, the following effects can be obtained.
The reverse osmosis membrane separation apparatus 1 according to the present embodiment includes a failure detection unit 301 that detects failure of the second flow sensor FM2, and a measurement value of the primary pressure of the waste water flow rate adjustment valve 7 when the second flow sensor FM2 fails. and the opening degree of the waste water flow rate adjustment valve 7, the waste water flow rate prediction unit 302 that calculates the predicted value of the waste water flow rate, and the recovery rate calculated from the flow rate of the permeated water W3 and the predicted value of the waste water flow rate is the recovery rate and an opening adjustment unit 303 that adjusts the opening of the drainage flow rate adjustment valve 7 so as to achieve the target recovery rate, which is the target value of .
As a result, even when the second flow rate sensor FM2 fails, it is possible to perform a backup operation with a recovery rate substantially equal to that in normal operation without stopping the apparatus.

In addition, the reverse osmosis membrane separation apparatus 1 is connected to the downstream end of the concentrated water line L4, and the circulating water line L5 that returns the concentrated water W4 as the supply water to the junction J2, and the concentrated water that passes through the concentrated water line L4. The pressure sensor P1 measures the pressure of the water supply W1 passing through the water supply line L1 as the primary pressure of the drainage flow control valve 7.
As a result, when the circulating water line L5 is provided in order to increase the circulation ratio and prevent clogging on the membrane surface of the RO membrane module 4, there is no need to separately provide pressure measuring means on the drainage line L6. A pressure sensor P1 provided in the water supply line L1 can be utilized as a means for measuring the primary pressure of the drainage flow control valve 7. FIG.

In addition, the reverse osmosis membrane separation device 1 is provided in the feed water line L2, and the pressure pump 2 that sucks the feed water W2 and discharges it toward the RO membrane module 4, and the flow rate of the permeated water W3 is set to a predetermined flow rate target. and a pump control unit 304 that controls the pressurizing pump 2 so as to obtain a value.
By controlling the flow rate of the permeated water W3 by constant flow rate feedback control, the permeated water W3 can be stably supplied.

[4 Modifications]
In the above embodiment, the reverse osmosis membrane separation device 1 is configured to include the circulating water line L5 and the check valve 6, but this is not restrictive. Specifically, the reverse osmosis membrane separation device 1 may be configured without the circulating water line L5 and the check valve 6 .

1 reverse osmosis membrane separator 2 pressure pump 3 pressure side inverter (inverter)
4 RO membrane module (reverse osmosis membrane module)
5 flow rate adjustment unit 7 drainage flow rate adjustment valve 12 water supply pump 13 water supply side inverter (inverter)
30 control unit 301 failure detection unit 302 drainage flow rate prediction unit 303 opening adjustment unit 304 pump control unit FM1, FM2 flow rate sensor (flow rate detection means)
P1 pressure sensor (pressure measuring means)
L1 feed water line L2 feed water line L3 permeated water line L4 concentrated water line L41 first concentrated water line L42 second concentrated water line

Claims (3)

a water supply line through which water is distributed;
a reverse osmosis membrane module that separates feed water into permeate and concentrate;
a feed water line connected to the feed water line at a confluence portion at an upstream end thereof and supplying feed water including feed water to the reverse osmosis membrane module;
a permeated water line through which the permeated water separated by the reverse osmosis membrane module passes;
a concentrated water line through which the concentrated water separated by the reverse osmosis membrane module passes;
A concentrated wastewater line connected to the downstream end of the concentrated water line and discharging concentrated water as concentrated wastewater to the outside of the system;
A drainage flow rate adjustment valve that adjusts the flow rate of concentrated water discharged to the outside of the device by adjusting the degree of opening substantially steplessly;
pressure measuring means for measuring the primary pressure of the drain flow rate control valve;
a first flow rate measuring means for measuring the flow rate of the permeated water;
a second flow rate measuring means for measuring the flow rate of the waste water;
failure detection means for detecting failure of the second flow rate measurement means;
a wastewater flow rate prediction means for calculating a predicted value of the wastewater flow rate from the measured value of the primary pressure of the wastewater flow rate adjustment valve and the degree of opening when the second flow rate measuring means fails;
opening adjustment means for adjusting the opening so that the recovery rate calculated from the flow rate of the permeated water and the predicted value of the waste water flow rate becomes a target recovery rate, which is a target value of the recovery rate;
A reverse osmosis membrane separation device. a circulating water line connected to the downstream end of the concentrated water line and returning the concentrated water as supply water to the junction;
a concentrated water flow rate adjusting means for adjusting the flow rate of concentrated water passing through the concentrated water line;
2. The reverse osmosis membrane separation apparatus according to claim 1, wherein said pressure measuring means measures the pressure of the water supply passing through said water supply line as the primary pressure of said wastewater flow rate control valve. a pressurizing pump provided in the feed water line for sucking feed water and discharging it as feed water toward the reverse osmosis membrane module;
3. The reverse osmosis membrane separation apparatus according to claim 1, further comprising pump control means for controlling said pressurizing pump so that the flow rate of permeate reaches a predetermined flow rate target value.

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