TW202035014A - Water treatment system - Google Patents

Abstract

This invention provides a water treatment system which can start up a back-stage pure water unit safely and rapidly after performing an initial blow for a front-stage pure water unit when the two pure water units are directly connecting and operated. A water treatment system (1) has a first film treatment device (D1) and a second film treatment device (D2), and sequentially executes a first step of driving a first boost pump (5) with a constant flow feedback control at a state of setting a first three-way valve (10) to a blow side when starting up the second film treatment device (D2), a second step of switching the first three-way valve (10) to a second film treatment device (D2) side and driving the first boost pump (5) with a fixed driving frequency, and a third step of driving the first boost pump (5) with a constant pressure feedback control and driving a second boost pump (11) with a constant flow feedback control.

Description

Water treatment system

The present invention relates to a water treatment system.

In the semiconductor manufacturing process, the cleaning of electronic parts, and medical equipment, high-purity pure water without impurities is used. Generally speaking, this kind of pure water system uses a reverse osmosis membrane module (hereinafter, also referred to as "RO ( Reverse Osmosis ) membrane module") as a membrane separation device to feed raw water such as groundwater and tap water (or even "supply Water") is manufactured by reverse osmosis membrane treatment.

In the past, a water treatment system has been proposed in which an RO membrane module and an electric deionization device process the feed water to produce pure water (for example, refer to Patent Documents 1 and 2). In addition, there is also known a water treatment system in which two RO membrane modules connected in series process feed water to produce pure water (for example, refer to Patent Document 3).

[Prior Technical Literature]

[Patent Literature]

[Patent Document 1] JP 2001-259376 A

[Patent Document 2] JP 2006-255650 A

[Patent Document 3] Japanese Patent No. 6056370

The water treatment system is directly connected with two pure water units such as reverse osmosis membrane modules. It is used to perform constant flow feedback (feed back) control during the initial blow of the pure water unit at the front stage. When the pure water unit starts, the control of the previous pure water unit must be switched to constant pressure feedback control.

The details will be described later, but when a treated water three-way valve is installed between the pure water unit at the front stage and the pure water unit at the rear stage, the treated water three-way valve will switch from the standby open discharge side to the rear pure water unit side. Therefore, if the control is not switched at an appropriate timing, the frequency will increase or decrease unnecessarily. When the frequency increases, the pressure of the treated water increases and the membrane may be damaged due to back pressure. When the frequency is reduced, it will not be able to keep up with the acceleration of the downstream pump and become negative pressure, and the pump and other equipment may be damaged.

The object of the present invention is to provide a water treatment system which can safely and quickly start the pure water unit at the front stage after the initial discharge of the pure water unit at the front stage is carried out when the water treatment system is directly connected to two pure water units. Water unit.

The present invention relates to a water treatment system, including: a first pure water unit, which produces first filtered water from feed water; a first pump, which sends feed water to the first pure water unit; and a pressure detection means, which The pressure of the first filtered water sent from the first pure water unit is output as the detected pressure value; the first flow detection means is the flow of the first filtered water sent from the first pure water unit as the first detected flow value Output; The second pure water unit is made from the first filtered water produced by the first pure water unit to produce the second filtered water; the supply object switching means is located between the second pure water unit side and the discharge side Switches the supply target of the first filtered water; the second pump sends the first to the second pure water unit Filtered water; The second flow detection means is to output the flow of the second filtered water produced by the second pure water unit as the second detected flow value; the first pump control unit drives the first pump; The second pump control unit drives the second pump; the switching means control unit switches the supply target switching means; and the activation control unit performs the following steps in sequence: The first step is in the second pure water When the unit is started, in a state where the switching means control unit has been instructed to set the supply target switching means to the discharge side, the first pump control unit is commanded so that the first detected flow rate value becomes the first target flow rate value. In the second step, the switching means control unit is made to switch the supply target switching means to the second pure water unit side, and the first pump control unit is made to drive the first pump at a fixed driving frequency. Pump; and the third step, so that the detected pressure value becomes the target pressure value, the first pump control unit drives the first pump, and the second detected flow value becomes the second target flow value , Let the second pump control unit drive the second pump.

In addition, in the water treatment system described above, it is preferable that the activation control unit is in the execution of the second step, and shifts to the execution of the third step at a time when the detected pressure value is lower than the target pressure value.

In addition, in the water treatment system described above, it is preferable that the activation control unit starts execution of the second step, and then shifts to the execution of the third step after a predetermined time has passed.

In addition, in the above-mentioned water treatment system, it is preferable that the fixed driving frequency falls within a predetermined threshold value which is higher than the operable lower limit frequency of the first pump.

According to the present invention, when two pure water units are directly connected for operation, the latter pure water unit can be safely and quickly activated after the initial discharge of the pure water unit at the front stage is performed.

1. 1A: Water treatment system

2: Feed water pump

3: Water-side inverter

4: Feed water pressure regulating valve

5: The first booster pump (the first pump)

6: The first voltage side inverter (the first inverter)

7: The first reverse osmosis membrane module (the first pure water unit)

8: The first flow adjustment valve

9: Drainage flow adjustment valve

10: The first three-way valve (supply object switching means)

11: The second booster pump (the second pump)

12: The second voltage side inverter (the second inverter)

13: The second reverse osmosis membrane module (the second pure water unit)

14: The second flow adjustment valve

15: The second three-way valve

30, 30A: Control Department

301: The first pump control unit

302: 2nd pump control unit

303: Switching means control unit

304: Start control section

D1: The first membrane treatment device

D2: The second membrane treatment device

FM 1: The first flow sensor

FM 2: The second flow sensor (the first flow detection means)

FM 3: The third flow sensor

FM 4: 4th flow sensor (2nd flow detection means)

J1, J2: connecting part

L1: Water supply line

L2: The first water supply line

L3: The first concentrated water line

L4: Circulating water circuit

L5: Concentrated drainage line

L6: The first water filter line

L7: The first filter drainage line

L8: The second water supply line

L9: The second concentrated water line

L10: 2nd filtered water line

L11: The second filter drainage line

L12: 3rd water filtration line

PS 1: The first pressure sensor

PS 2: 2nd pressure sensor

PS 3: The third pressure sensor (pressure detection means)

PS 4: 4th pressure sensor

S11~S17: steps

W1: Water supply

W2: The first water supply (supply water)

W3: The first concentrated water

W4: circulating water

W5: Concentrated drainage

W6: The first filtered water

W8: The second water supply

W9: 2nd concentrated water

W10: 2nd filtered water

W12: 3rd filtered water

Figure 1 is a diagram showing the overall configuration of a water treatment system according to an embodiment of the present invention.

Fig. 2 is a graph showing the relationship between the pressure and the flow rate of the flow control valve used in the embodiment of the present invention.

Fig. 3 is a functional block diagram of the control unit included in the water treatment system according to the embodiment of the present invention.

Fig. 4A is a diagram showing the transition of the operation mode of the water treatment system according to the embodiment of the present invention.

Fig. 4B is a diagram showing the transition of the operation mode of the water treatment system according to the embodiment of the present invention.

Fig. 4C is a diagram showing the transition of the operation mode of the water treatment system according to the embodiment of the present invention.

Figure 5 is a flowchart showing the operation of the water treatment system according to the embodiment of the present invention.

Figure 6A is a diagram showing the transition of the operation mode of the water treatment system of the prior art.

Figure 6B is a diagram showing the transition of the action mode of the water treatment system of the prior art.

Figure 6C is a diagram showing the transition of the action mode of the water treatment system of the prior art.

Figure 7A is a diagram showing the transition of the action mode of the water treatment system of the prior art.

Figure 7B is a diagram showing the transition of the action mode of the water treatment system of the prior art.

Hereinafter, the water treatment system 1 according to the embodiment of the present invention will be described in detail with reference to FIGS. 1 to 5.

[1 Configuration of the embodiment]

Figure 1 is an overall configuration diagram of the water treatment system 1 of this embodiment.

As shown in FIG. 1, the water treatment system 1 includes a first membrane treatment device D1, a second membrane treatment device D2, and a control unit 30.

In addition, the first membrane processing device D1 is equipped with: a feed water pump 2, a feed water side inverter (inverter) 3, a feed water pressure regulating valve 4, a first pressure sensor PS1, a first pressure pump 5 (first pump) , The first pressure side inverter 6 (first inverter), the second pressure sensor PS2, the third pressure sensor PS3, the first reverse osmosis membrane module 7 (first pure water unit), The first flow rate adjustment valve 8, the drain flow rate adjustment valve 9, the first flow rate sensor FM1, the second flow rate sensor FM2, and the first three-way valve 10.

In addition, in terms of lines, the first membrane treatment device D1 includes: a water supply line L1, a first water supply line L2, a first concentrated water line L3, a circulating water line L4, a concentrated drainage line L5, and a first Filter water line L6. "Line" is a general term for lines, channels, piping, etc. through which fluid can circulate. In addition, regardless of its origin (source) or its water quality, the water circulating in the water supply line L1, the first concentrated water line L3, or the circulating water line L4 is also referred to as "water supply", and will circulate in the first concentrated water line L3 The water in the circulating water line L4 or the concentrated drainage line L5 is also called "concentrated water".

The water supply line L1 is a line that supplies the water supply W1 to the connection part J1 which is the junction of the first water supply line L2. The upstream end of the water supply line L1 is connected to a supply source (not shown) of the water supply W1. In the water supply line L1, a water supply pump 2, a water supply pressure adjustment valve 4, and a connection part J1 are provided in this order from the upstream side to the downstream side.

In addition, the feed water W1 circulating in the water supply line L1 is not limited to the feed water directly supplied from the supply source (not shown) of the feed water W1, and includes, for example, a filtration treatment device (iron and manganese removal device, active The feed water obtained by pre-processing the feed water W1 by a pre-processing device such as a carbon filter device, etc.) and a hard water softening device.

The water supply pump 2 is a device that sucks in the water supply W1 flowing through the water supply line L1 and pressure-feeds (sends) the water to the first pressure pump 5 as the first supply water W2. For feed water pump 2 The inverter 3 converts the driving power obtained by frequency conversion. The feed water pump 2 is driven at a rotation speed corresponding to the frequency of the supplied (input) driving power (hereinafter, also referred to as "driving frequency").

The feedwater-side inverter 3 is an electric circuit (or a device having this circuit) that supplies drive power obtained by frequency conversion to the feedwater pump 2. The water supply side inverter 3 is electrically connected to the control unit 30. A command signal is input from the control unit 30 to the water-side inverter 3. The water-side inverter 3 outputs, to the water-supply pump 2, driving power at a driving frequency corresponding to the command signal (current value signal or voltage value signal) input by the control unit 30.

The feedwater pressure adjusting valve 4 is a valve that adjusts the pressure of the feedwater W1 flowing through the feedwater line L1. The feed water pressure regulating valve 4 is electrically connected to the control unit 30. The opening degree of the feed water pressure adjusting valve 4 is controlled by the control unit 30. The feed water pressure adjusting valve 4 may be, for example, a solenoid valve.

Particularly in the present embodiment, the opening degree of the feed water pressure adjusting valve 4 is adjusted so that the pressure value of the first feed water W2 measured by the first pressure sensor PS1 described later becomes a fixed value.

The first water supply line L2 is a line that supplies the feed water W1 as the first feed water W2 to the first reverse osmosis membrane module 7. The upstream end of the first water supply line L2 is connected to the connection portion J1. The downstream end of the first water supply line L2 is connected to the primary side inlet port of the first reverse osmosis membrane module 7. In the first water supply line L2, a connection part J1, a first pressure sensor PS1, a first pressure pump 5, a second pressure sensor PS2, and a first inverse are provided in order from the upstream side to the downstream side. Permeable membrane module 7.

The first pressure sensor PS1 is a device that detects the pressure of the water supply W1 from the connection portion J1 to the first pressure pump 5 in the first water supply line L2. The pressure of the first supply water W2 detected by the first pressure sensor PS1 is sent to the control unit 30 as a detection signal.

The first pressure pump 5 is provided in the first water supply line L2. The first pressurizing pump 5 is a device that sucks the feed water W1 in the first water supply line L2 and pressure-feeds (sends) the water to the first reverse osmosis membrane module 7 as the first feed water W2. The drive power obtained by frequency conversion by the first pressure-side inverter 6 is supplied to the first pressure pump 5. The first pressure pump 5 is driven at a rotation speed corresponding to the frequency of the supplied (input) driving power (hereinafter, also referred to as "driving frequency").

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

The second pressure sensor PS2 is a device that detects the pressure of the first supply water W2 from the first pressure pump 5 to the first reverse osmosis membrane module 7 in the first water supply line L2. The pressure of the first supply water W2 detected by the second pressure sensor PS2 is sent to the control unit 30 as a detection signal.

The first reverse osmosis membrane module 7 is for the first feed water W2 sent from the first pressure pump 5, the first filtered water W6 obtained after removing the dissolved salts, and the first concentration obtained by concentrating the dissolved salts Equipment for membrane separation treatment of water W3. The first reverse osmosis membrane module 7 is equipped with a single or plural RO membrane elements (not shown). The first reverse osmosis membrane module 7 uses these RO membrane elements to subject the first feed water W2 to a membrane separation process to produce the first concentrated water W3 and the first filtered water W6.

The first concentrated water line L3 is a line for sending out the first concentrated water W3 separated by the first reverse osmosis membrane module 7. The upstream end of the first concentrated water line L3 is connected to the primary outlet port of the first reverse osmosis membrane module 7. In addition, the downstream side of the first concentrated water line L3 is connected The junction J2 is divided into circulating water line L4 and concentrated drainage line L5. In the first concentrated water line L3, a first flow rate adjustment valve 8 and a connection portion J2 are provided in this order from the upstream side to the downstream side.

The first flow adjustment valve 8 is equipped with: a constant flow element, which can substantially circulate a constant flow of the first concentrated water W3 regardless of the differential pressure in the first flow adjustment valve 8; and a proportional element, which is consistent with the first The differential pressure in the flow adjustment valve 8 is substantially proportional to increase the flow rate of the first concentrated water W3. Specifically, the differential pressure in the first flow control valve 8 is the differential pressure of the water pressure in the front and back lines of the first flow control valve 8. The constant flow element does not require auxiliary power or external operation to maintain a fixed flow value. For example, what is called a water regulator can also be used. In addition, as a proportional element, for example, what is called an orifice may be used, and the flow rate of the first concentrated water W3 flowing from the orifice is proportional to the differential pressure in the first flow rate adjusting valve 8.

FIG. 2 is a graph showing an example of the relationship between the inlet pressure of the first reverse osmosis membrane module 7 and the flow rate of concentrated water flowing through the first flow rate adjusting valve 8. The first flow control valve 8 has a constant flow element, so when an inlet pressure is generated, the flow rate of the concentrated water flowing through the first flow control valve 8 will rise sharply to point A. That is, roughly speaking, at the same time as the inlet pressure is generated, the flow having the height of the A point flows to the first flow adjusting valve 8. At the same time, since the first flow rate adjustment valve 8 has a proportional element, the flow rate of the concentrated water flowing through the first flow rate adjustment valve 8 will increase in a linear function as the inlet pressure increases.

Furthermore, in the first flow control valve 8, the constant flow element and the proportional element system may be configured as a single body, or may be configured as separate entities. When integrated, for example, the flow direction of the proportional element may coincide with the long axis direction of the first flow adjustment valve 8, and the flow direction of the constant flow element is orthogonal to the long axis direction of the first flow adjustment valve 8. . Or it may be configured such that the flow direction of the proportional element is orthogonal to the long axis direction of the first flow control valve 8, and the flow direction of the constant flow element is the same as the length of the first flow control valve 8. The axis directions are the same. Alternatively, it may be configured that the flow direction of the constant flow element and the flow direction of the proportional element both coincide with the major axis direction of the first flow adjustment valve 8.

The circulating water line L4 is a line that is connected to the first concentrated water line L3 and returns concentrated water (circulating water W4) as feed water to the water feed line L1. In this embodiment, the circulating water line L4 uses the first concentrated water W3 circulating in the first concentrated water line L3 as circulating water W4 and returns (circulates) it to a pressure higher than the first pressure of the first water supply line L2 Line on the more upstream side of pump 5. The upstream end of the circulating water line L4 is connected to the first concentrated water line L3 at the connection part J2. In addition, the downstream end of the circulating water line L4 is connected to the water supply line L1 and the first water supply line L2 in the connection portion J1.

The concentrated drainage line L5 is a line that is connected to the first concentrated water line L3 and discharges concentrated water as the concentrated drainage W5 to the outside of the system. In this embodiment, the concentrated drainage line L5 is connected to the first concentrated water line L3 in the connection portion J2, and the first concentrated water W3 separated by the first reverse osmosis membrane module 7 is used as the concentrated drainage W5. The line discharged to the outside of the device (outside the system). In the concentrated drainage line L5, a first flow sensor FM1 and a drainage flow adjustment valve 9 are provided.

The first flow sensor FM1 is a device that detects the flow rate of the concentrated drainage W5 flowing through the concentrated drainage line L5. The first flow sensor FM1 is connected to the concentrated drainage line L5. The first flow sensor FM1 is electrically connected to the control unit 30. The first detected flow rate value of the concentrated waste water W5 detected by the first flow sensor FM1 is transmitted to the control unit 30 as a detection signal. As the first flow sensor FM1, for example, a pulse transmission type flow sensor can be used, in which an axial flow impeller or a tangential impeller (not shown) is arranged in a flow path cover.

The drain flow rate adjustment valve 9 is a valve that adjusts the flow rate of the concentrated drain W5 discharged from the concentrated drain line L5 to the outside of the device. The drain flow adjustment valve 9 is electrically connected to the control unit 30. The valve opening degree of the drain flow rate adjustment valve 9 is controlled by a drive signal sent from the control unit 30. By calculating the current value The number (for example, 4 to 20 mA) is sent from the control unit 30 to the drain flow rate adjustment valve 9 to perform valve opening control, and the drain flow rate of the concentrated drain W5 can be adjusted.

Particularly in the present embodiment, the opening degree of the drainage flow rate adjustment valve 9 is adjusted so that the flow rate value of the concentrated drainage W5 measured by the first flow sensor FM1 described later becomes a fixed value.

The first filtered water line L6 is a line for sending out the first filtered water W6 obtained by separating (manufacturing) the first reverse osmosis membrane module 7. The upstream end of the first filtered water line L6 is connected to the secondary side port of the first reverse osmosis membrane module 7. The downstream end of the first filtered water line L6 is connected to the first three-way valve 10. A third pressure sensor PS3 and a second flow sensor FM2 are provided in the first filtered water line L6.

The third pressure sensor PS3 (hereinafter also referred to as "pressure detection means") is in the first filtered water line L6 to detect the first filtered water W6 from the first reverse osmosis membrane module 7 to the first three-way valve 10 The pressure of the machine. The pressure of the first filtered water W6 (hereinafter also referred to as "detected pressure value") detected by the third pressure sensor PS3 is sent to the control unit 30 as a detection signal.

The second flow sensor FM2 (hereinafter, also referred to as "first flow detection means") detects the flow rate of the first filtered water W6 flowing through the first filtered water line L6 (hereinafter, also referred to as "first detection flow rate"). Value"). The second flow sensor FM2 is connected to the first filtered water line L6. The second flow sensor FM2 is electrically connected to the control unit 30. The second detected flow rate value of the first filtered water W6 detected by the second flow rate sensor FM2 is sent to the control unit 30 as a detection signal. As the second flow sensor FM2, for example, a pulse transmission type flow sensor can be used, in which an axial flow impeller or a tangential impeller (not shown) is arranged in a flow path cover.

The first three-way valve 10 (hereinafter, also referred to as "supply object switching means") is connected to the first filtered water line L6, the first filtered drain line L7, and supplies the second supply to the second membrane treatment device D2 The second water supply line L8 of water W8. The first three-way valve 10 switches the supply target of the first filtered water W6 flowing in the first filtered water line L6 between the first filtered drainage line L7 and the second membrane treatment device D2. That is, in a state where the flow path from the first filtered water line L6 to the first filtered drain line L7 is closed by the first three-way valve 10, the total amount of the first filtered water W6 flowing through the first filtered water line L6 The amount will flow toward the second water supply line L8 side. When the first three-way valve 10 switches the flow path, the first three-way valve 10 closes the flow path from the first filtered water line L6 to the second water supply line L8, and flows through the first filtered water line L6 The total amount of the first filtered water W6 will flow toward the first filtered drainage line L7 side. As described above, the first three-way valve 10 switches the flow path between the first filtered drainage line L7 and the second water supply line L8.

The second membrane processing device D2 is equipped with: a fourth pressure sensor PS4, a second pressure pump 11 (second pump), a second pressure side inverter 12 (second inverter), and a second reverse osmosis The membrane module 13 (the second pure water unit), the second flow regulating valve 14, the third flow sensor FM3, the second three-way valve 15, and the fourth flow sensor FM4.

In addition, in terms of lines, the second membrane treatment device D2 is equipped with: a second water supply line L8, a second concentrated water line L9, a second filtered water line L10, a second filtered drain line L11, and a third filtered water line L12.

The second water supply line L8 is a line for supplying the second water supply W8 to the second reverse osmosis membrane module 13. The upstream end of the second water supply line L8 is connected to the first three-way valve 10. The downstream end of the second water supply line L8 is connected to the primary side inlet port of the second reverse osmosis membrane module 13. In the second water supply line L8, a fourth pressure sensor PS4 and a second pressure pump 11 are provided in this order from the upstream side to the downstream side.

The fourth pressure sensor PS4 is a device that detects the pressure of the second supply water W8 from the first three-way valve 10 to the second pressure pump 11 in the second water supply line L8. The pressure of the second supply water W8 (hereinafter, also referred to as "fourth detected pressure value") detected by the fourth pressure sensor PS4 is sent to the control unit 30 as a detection signal.

The second pressure pump 11 is a device that sucks in the second water supply W8 through the second water supply line L8 and pressure-feeds (sends it) to the second reverse osmosis membrane module 13. The second pressure pump 11 is supplied with drive power obtained by frequency conversion by the second pressure side inverter 12. The second pressure pump 11 is driven at a rotation speed corresponding to the frequency of the supplied (input) driving power (hereinafter also referred to as "driving frequency").

The second pressurizing side inverter 12 is an electric circuit (or a device having this circuit) that supplies drive power obtained by frequency conversion to the second pressurizing pump 11. The second pressure-side inverter 12 is electrically connected to the control unit 30. The command signal is input from the control unit 30 to the second pressure-side inverter 12. The second pressurizing side inverter 12 outputs to the second pressurizing pump 11 drive power at a drive frequency corresponding to the command signal (current value signal or voltage value signal) input by the control unit 30.

The second reverse osmosis membrane module 13 is for the second feed water W8 sent from the second pressure pump 11, the second filtered water W10 obtained by removing the dissolved salts, and the second filtered water obtained by concentrating the dissolved salts. Equipment for membrane separation treatment of concentrated water W9. The second reverse osmosis membrane module 13 includes a single or plural RO membrane elements (not shown). The second reverse osmosis membrane module 13 uses these RO membrane elements to subject the second feed water W8 to a membrane separation process to produce the second concentrated water W9 and the second filtered water W10.

The second concentrated water line L9 is a line for sending out the second concentrated water W9 separated by the second reverse osmosis membrane module 13. The upstream end of the second concentrated water line L9 is connected to the primary outlet port of the second reverse osmosis membrane module 13. In the second concentrated water line L9, a second flow control valve 14 and a third flow sensor FM3 are provided in this order from the upstream side to the downstream side.

The second flow adjustment valve 14 is equipped with: a constant flow element, which can substantially circulate a constant flow of the second concentrated water W9 regardless of the differential pressure in the second flow adjustment valve 14; and a proportional element, which is consistent with the second The differential pressure in the flow control valve 14 is substantially proportional to increase the flow rate of the second concentrated water W9.

In addition, since the structure and function of the 2nd flow rate adjustment valve 14 are the same as that of the 1st flow rate adjustment valve 8, the description is abbreviate|omitted.

The third flow sensor FM3 is a device that detects the flow rate of the second concentrated water W9 flowing through the second concentrated water line L9. The third flow sensor FM3 is electrically connected to the control unit 30. The third detection flow rate value of the second concentrated water W9 detected by the third flow sensor FM3 is sent to the control unit 30 as a detection signal. As the third flow sensor FM3, for example, a pulse transmission type flow sensor can be used, in which an axial flow impeller or a tangential impeller (not shown) is arranged in the flow path cover.

The second filtered water line L10 is a line for sending out the second filtered water W10 obtained by separating (manufacturing) the second reverse osmosis membrane module 13. The upstream end of the second filtered water line L10 is connected to the secondary side port of the second reverse osmosis membrane module 13. The downstream end of the second filtered water line L10 is connected to the second three-way valve 15. A fourth flow sensor FM4 is provided in the second filtered water line L10.

The fourth flow sensor FM4 (hereinafter, also referred to as "second flow detection means") detects the flow rate of the second filtered water W10 flowing through the second filtered water line L10 (hereinafter, also referred to as "second detection flow rate"). Value"). The fourth flow sensor FM4 is electrically connected to the control unit 30. The second detected flow rate value of the second filtered water W10 detected by the fourth flow sensor FM4 is sent to the control unit 30 as a detection signal. For the fourth flow sensor FM4, for example, a pulse transmission type flow sensor can be used, in which an axial flow impeller or a tangential impeller (not shown) is arranged in a flow path cover.

The second three-way valve 15 connects the second filtered water line L10, the second filtered water drainage line L11, and the third filtered water line L12. The second three-way valve 15 is connected to the second filter drainage line L11 and the third The filtered water line L12 switches the supply target of the second filtered water W10 flowing in the second filtered water line L10. That is, in a state where the flow path from the second filtered water line L10 to the second filtered drain line L11 is closed by the second three-way valve 15, the total amount of the second filtered water W10 flowing through the second filtered water line L10 The amount will flow toward the third filtered water line L12 side. When the second three-way valve 15 switches the flow path, the flow path from the second filtered water line L10 to the third filtered water line L12 is closed by the second three-way valve 15 and flows through the second filtered water line L10 The total amount of the second filtered water W10 will flow toward the second filtered drain line L11 side. As described above, the second three-way valve 15 switches the flow path between the second filtered drainage line L11 and the third filtered water line L12.

The third filtered water line L12 is a line that sends out the third filtered water W12 separated by the second three-way valve 15. The upstream end of the third filtered water line L12 is connected to the second three-way valve 15. The downstream end of the third filtered water line L12 is connected to a device or the like at a desired location.

The control unit 30 is constituted by a microprocessor (not shown) including a CPU and a memory. In the control unit 30, the CPU of the microprocessor executes various controls related to the water treatment system 1 according to a predetermined program read from the memory. Hereinafter, some functions of the control unit 30 will be described.

Fig. 3 shows the functional block of the control unit 30. The control unit 30 includes a first pump control unit 301, a second pump control unit 302, a switching means control unit 303, and an activation control unit 304.

The first pump control unit 301 drives the first pressure pump 5. More specifically, the first pump control unit 301 rotates so that the first detected flow rate value detected by the second flow rate sensor FM2 becomes the first target flow rate value when the second membrane processing device D2 is activated. Speed drives the first pressure pump 5. In addition, the first pump control unit 301 drives the first filter at a rotation speed corresponding to a fixed driving frequency after switching the supply target of the first filtered water W6 to the second membrane processing device D2 side by the first three-way valve 10 Pressure pump 5. Furthermore, the fixed driving frequency falls above the lower limit frequency of the operation of the first booster pump 5. The range within the predetermined threshold. Then, the first pump control unit 301 drives the first pressure pump 5 at a rotation speed such that the detected pressure value detected by the third pressure sensor PS3 becomes the target pressure value. In addition, "fixed" may be substantially fixed, or may be changed slightly within the scope of achieving the effect of the invention.

The second pump control unit 302 drives the second pressure pump 11. More specifically, as described above, when the first pump control unit 301 drives the first pressurizing pump 5 at a rotation speed such that the detected pressure value detected by the third pressure sensor PS3 becomes the target pressure value, The second pump control unit 302 drives the second pressure pump 11 at a rotation speed at which the second detected flow rate value detected by the fourth flow rate sensor FM4 becomes the second target flow rate value.

The switching means control unit 303 switches the supply target of the first filtered water W6 on the second membrane treatment device D2 side or the drain side with respect to the first three-way valve 10 as the supply target switching means. More specifically, when the second membrane treatment device D2 is activated, the supply target of the first filtered water W6 to the first three-way valve 10 is set to the discharge side. Then, as described above, after the first pump control unit 301 drives the first pressurizing pump 5 at a rotation speed such that the first detected flow rate value becomes the first target flow rate value, the switching means control unit 303 responds to the supply target switching means The first three-way valve 10 sets the supply target of the first filtered water W6 to the second membrane treatment device D2 side.

The activation control unit 304 controls the operation at the time of activation by changing the operation mode of the water treatment system 1.

In more detail, in the first step, the activation control unit 304 is used when the second membrane processing device D2 is activated, when the switching means control unit 303 has been ordered to use the first three-way valve 10 to remove the first filtered water W6 In a state where the supply target is the discharge side, the first pump control unit 301 is caused to drive the first pressure pump 5 so that the first detected flow rate value becomes the first target flow rate value.

In addition, in the second step, the activation control unit 304 causes the switching means control unit 303 to switch the supply target of the first filtered water W6 to the second membrane treatment device D2 side through the first three-way valve 10, and the first The pump control unit 301 drives the first pressure pump 5 at a fixed drive frequency.

In addition, in the third step, the activation control unit 304 causes the first pump control unit 301 to drive the first pressurization so that the detected pressure value detected by the third pressure sensor PS3 becomes the target pressure value. The pump 5 also causes the second pump control unit 302 to drive the second pressure pump 11 so that the second detected flow rate value detected by the fourth flow rate sensor FM4 becomes the second target flow rate value.

Furthermore, the activation control unit 304 may shift to the execution of the third step when the detected pressure value is lower than the target pressure value during the execution of the second step. Alternatively, the activation control unit 304 may shift to the execution of the third step after a predetermined time has elapsed after starting the execution of the second step.

[2 Operation of the implementation mode]

Hereinafter, referring to FIG. 4A, FIG. 4B, and FIG. 5, the operation of the water treatment system 1 of this embodiment will be described. As its premise, referring to FIGS. 6A to 6C and FIGS. 7A to 7B, the problems of the conventional technology will be described in detail.

Furthermore, FIGS. 6A to 6C and FIGS. 7A to 7B illustrate the structure of a water treatment system 1A according to the prior art, but the structure is basically the same as the water treatment system 1 of this embodiment , So the description of each component is omitted. The water treatment system 1A is different from the water treatment system 1 in that it includes a control unit 30A instead of the control unit 30. The control unit 30A does not include the first pump control unit 301, the second pump control unit 302, and the control unit 30. The switching means control unit 303 and the activation control unit 304.

FIGS. 6A to 6C show the transition of the operation when the constant pressure feedback control is performed during the switching of the first three-way valve 10 in the water treatment system 1 of the prior art.

As shown in FIG. 6A, in the first step, the initial discharge of the first film processing device D1 is performed. During this period, the first three-way valve 10 causes the total amount of the first filtered water W6 flowing through the first filtered water line L6 to flow toward the discharge side, that is, the first filtered drain line L7 side. At this time, since the treated water pressure, that is, the detected pressure value detected by the third pressure sensor PS3, cannot be used, the first detected flow value detected by the second flow sensor FM2 is used. The first pressure pump 5 is subjected to constant flow feedback control. Furthermore, sometimes "feedback" is omitted as "FB".

As shown in FIG. 6B, in the second step, the first three-way valve 10 switches the supply target of the first filtered water W6 from the discharge side to the second membrane treatment device D2 side. At this time, since the second pressurizing pump 11 provided in the second membrane processing device D2 has not been activated yet, the pressure loss in the second membrane processing device D2 is relatively high, and the pressure of the processing water belonging to the first membrane processing device D1 is borrowed The detected pressure value detected by the third pressure sensor PS3 increases. In addition, the frequency (rotation speed) of the first pressure pump 5 is extremely reduced.

As shown in FIG. 6C, in the third step, the initial discharge of the second film processing device D2 is performed. Specifically, although the second pressure pump 11 will start to operate, the pressure of the treated water belonging to the first membrane treatment device D1, which is detected by the third pressure sensor PS3, is still higher than the target pressure. , So the first pressure pump 5 will continue to decelerate.

When the detected pressure value detected by the third pressure sensor PS3 is lower than the target pressure value and the second pressure pump 11 is accelerating, the frequency of the first pressure pump 5 becomes close to 0 Hz, and The frequency of the second pressure pump 11 becomes a frequency higher than a predetermined value. Therefore, the acceleration of the first pressure pump 5 cannot keep up with the acceleration of the second pressure pump 11 and becomes negative pressure, and cavitation occurs in the first pressure pump 5 and is damaged.

FIGS. 7A to 7B show the transition of the operation when the constant flow rate feedback control is performed during the switching of the first three-way valve 10 in the conventional water treatment system 1A.

As shown in FIG. 7A, in the first step, the initial discharge of the first film processing device D1 is performed. During this period, the first three-way valve 10 causes the total amount of the first filtered water W6 flowing through the first filtered water line L6 to flow toward the discharge side, that is, the first filtered drain line L7 side. At this time, since the treated water pressure, that is, the detected pressure value detected by the third pressure sensor PS3, cannot be used, the first detected flow value detected by the second flow sensor FM2 is used. The first pressure pump 5 is subjected to constant flow feedback control.

As shown in FIG. 7B, in the second step, the first three-way valve 10 switches the supply target of the first filtered water W6 from the discharge side to the second membrane treatment device D2 side. At this time, since the second pressurizing pump 11 provided in the second membrane treatment device D2 has not been activated, the pressure loss in the second membrane treatment device D2 is relatively high, and the first membrane treatment device D1 belongs to the first treatment water. The flow of filtered water W6 will decrease. The first pressurizing pump 5 will continue to increase the frequency when the target flow rate is to flow, and the pressure of the treated water belonging to the first membrane processing device D1 will continue to be detected by the third pressure sensor PS3. Becomes high. As a result, the detected pressure value becomes higher than the reverse pressure of the membrane outlet pressure of the first reverse osmosis membrane module 7, and the reverse osmosis membrane of the first reverse osmosis membrane module 7 is damaged.

Therefore, in the water treatment system 1 of the present embodiment, the driving frequency of the first pressure pump 5 is fixed when the first three-way valve 10 is used to switch the supply target of the first filtered water W6. 4A to 4C show the transition of the operation when the driving frequency of the first pressure pump 5 is fixed during the switching of the first three-way valve 10 in the water treatment system 1 of the present embodiment.

As shown in FIG. 4A, in the first step, the initial discharge of the first film processing device D1 is performed. During this period, the first three-way valve 10 causes the total amount of the first filtered water W6 flowing through the first filtered water line L6 to flow toward the discharge side, that is, the first filtered drain line L7 side. At this time, since the treated water pressure, that is, the detected pressure value detected by the third pressure sensor PS3, cannot be used, the borrowed The first pressure pump 5 is subjected to constant flow rate feedback control by the first detected flow rate value detected by the second flow rate sensor FM2.

As shown in FIG. 4B, in the second step, the first three-way valve 10 switches the supply target of the first filtered water W6 from the discharge side to the second membrane treatment device D2 side. At this time, the driving frequency of the first pressure pump 5 is fixed at a frequency that is approximately half of the highest frequency. For example, when the highest frequency is a 60 Hz specification, it is fixed at 30 Hz. This is because if the driving frequency is high, the pressure of the treated water generated by the first membrane treatment device D1 will become too high, causing back pressure, which may damage the first reverse osmosis membrane module 7. On the other hand, if the driving frequency is low, the acceleration of the first pressure pump 5 will not be able to keep up when the second pressure pump 11 starts to operate, resulting in negative pressure, and cavitation occurs in the first pressure pump 5. The first pressure pump 5 may be damaged.

As shown in FIG. 4C, in the third step, the initial discharge of the second film processing device D2 is performed. Specifically, the second pressure pump 11 starts to operate, and when the detected pressure value detected by the third pressure sensor PS3 is lower than the target pressure value (for example, 0.1 MPa) or exceeds the target pressure value for a fixed time, The first pressure pump 5 is switched to feedback control using the detected pressure value detected by the third pressure sensor PS3. Furthermore, the fixed time is set because there is a possibility that the detected pressure value detected by the third pressure sensor PS3 is not lower than the target pressure value.

Fig. 5 is a flowchart showing the operation of the water treatment system 1 according to the embodiment of the present invention. Hereinafter, the operation of the water treatment system 1 will be described with reference to FIG. 5.

In step S11, the constant flow rate feedback control is started in the first membrane processing apparatus D1.

In step S12, the switching of the first three-way valve 10 is started. More specifically, the first three-way valve 10 starts an operation to switch the supply target of the first filtered water W6 flowing through the first filtered water line L6 from the discharge side to the second membrane treatment device D2 side.

In step S13, the driving frequency of the first pressure pump 5 is fixed.

In step S14, when the switching of the first three-way valve 10 ends (S14: YES), the processing system shifts to step S15. When the switching of the first three-way valve 10 has not yet been completed (S14: NO), the process proceeds to step S14.

In step S15, the constant flow rate feedback control is started in the second membrane processing apparatus D2.

In step S16, when the processing water pressure of the first membrane processing device D1 is lower than the target pressure value (S16: Yes), the processing system shifts to step S17. When the treatment water pressure of the first membrane treatment device D1 is equal to or higher than the target pressure value (S16: No), the treatment system shifts to step S18.

In step S17, the constant pressure feedback control is started in the first membrane processing apparatus D1.

In step S18, after a predetermined time has passed (S18: YES), the processing system shifts to step S17. When the predetermined time has not elapsed (S18: No), the processing system shifts to step S16.

[3 Effects of the implementation form]]

The water treatment system 1 of this embodiment includes: a first pump control unit 301, which drives the first pressure pump 5; a second pump control unit 302, which drives the second pressure pump 11; and a switching means control unit 303, which drives Switching the first three-way valve 10 as the supply target switching means; and the activation control unit 304 executes the following steps in order: The first step is when the second membrane processing device D2 is activated, and the switching means has been commanded to control The section 303 sets the first three-way valve 10 as the supply target switching means on the discharge side, and causes the first pump control section 301 to drive the first pressurizing so that the first detected flow rate value becomes the first target flow rate value. Pump 5; The second step is to instruct the switching means control unit 303 to switch the first three-way valve 10 as the supply target switching means to the second membrane processing device D2 side, and to instruct the first pump control unit 301 to drive the first pump at a fixed drive frequency 1 booster pump 5; and the third step is to make the first pump control unit 301 drive the first booster pump 5 so that the detected pressure value becomes the target pressure value, and the second detected flow rate value becomes the second With the target flow rate value, the second pump control unit 302 is caused to drive the second pressure pump 11.

With this, when operating a water treatment system directly connected to a pure water unit such as a reverse osmosis membrane module, it is possible to suppress the possibility of negative pressure and back pressure, and to safely start the downstream device. In addition, the acceleration time of the subsequent pump can be accelerated and the start-up time can be shortened.

In addition, in the water treatment system 1 of the present embodiment, the activation control unit 304 is in the execution of the second step, and shifts to the execution of the third step when the detected pressure value is lower than the target pressure value.

As a result, the pressure of the treated water generated by the pure water unit in the front stage will remain higher than the target value for a short period after the start of the pressurizing pump in the latter stage, while the treated water pressure generated by the pure water unit in the front stage will be lower At the time point of the target value, the frequency of the pressure pump in the previous stage can be fixed, and the constant pressure feedback operation can be quickly transferred.

In addition, in the water treatment system 1 of this embodiment, the activation control unit 304 starts the execution of the second step and then shifts to the execution of the third step after a predetermined time has passed.

With this, when the pressure of the treated water generated by the pure water unit in the previous stage is not lower than the target pressure, the second step can be shifted to the third step.

In addition, in the water treatment system 1 of the present embodiment, the fixed drive frequency falls within a predetermined threshold value which is higher than the operable lower limit frequency of the first pressure pump 5.

If the driving frequency is high, the pressure of the treated water becomes too high and back pressure is generated, which may damage the first reverse osmosis membrane module 7. In addition, if the driving frequency is low, there will be the acceleration of the pump in the front stage at the back When the pump of the stage starts to move, it cannot keep up and forms negative pressure, and cavitation may occur and the pump may be damaged. It is possible to set the drive frequency within the predetermined threshold value above the lower limit frequency of operation in the range below the maximum frequency, thereby preventing this phenomenon.

[4 Modifications]

The above-described embodiment includes the first reverse osmosis membrane module 7 in the first stage and the second reverse osmosis membrane module 13 in the second stage, but it is not limited to this. The water treatment system of the present invention is not limited to those provided with a two-stage pure water unit. The number of stages can also be 3 or more. The pure water unit can also be an electric regenerative ion exchange device or a decarbonation membrane device.

An example of the combination of the number of stages and the pure water unit is shown below.

RO: reverse osmosis membrane module

EI: Electric regenerative ion exchange device

Decarbonation membrane: Decarbonation membrane device

1: Water treatment system

2: Feed water pump

3: Water-side inverter

4: Feed water pressure regulating valve

5: The first booster pump (the first pump)

6: The first voltage side inverter (the first inverter)

7: The first reverse osmosis membrane module (the first pure water unit)

8: The first flow adjustment valve

9: Drainage flow adjustment valve

10: The first three-way valve (supply object switching means)

11: The second booster pump (the second pump)

12: The second voltage side inverter (the second inverter)

13: The second reverse osmosis membrane module (the second pure water unit)

14: The second flow adjustment valve

15: The second three-way valve

30: Control Department

D1: The first membrane treatment device

D2: The second membrane treatment device

FM 1: The first flow sensor

FM 2: The second flow sensor (the first flow detection means)

FM 3: The third flow sensor

FM 4: 4th flow sensor (2nd flow detection means)

J1, J2: connecting part

L1: Water supply line

L2: The first water supply line

L3: The first concentrated water line

L4: Circulating water circuit

L5: Concentrated drainage line

L6: The first water filter line

L7: The first filter drainage line

L8: The second water supply line

L9: The second concentrated water line

L10: 2nd filtered water line

L11: The second filter drainage line

L12: 3rd water filtration line

PS 1: The first pressure sensor

PS 2: 2nd pressure sensor

PS 3: The third pressure sensor (pressure detection means)

PS 4: 4th pressure sensor

W1: Water supply

W2: The first water supply (supply water)

W3: The first concentrated water

W4: circulating water

W5: Concentrated drainage

W6: The first filtered water

W8: The second water supply

W9: 2nd concentrated water

W10: 2nd filtered water

W12: 3rd filtered water

Claims (4)

A water treatment system with: The first pure water unit produces the first filtered water from the supply water; The first pump sends out the supply water to the aforementioned first pure water unit; The pressure detection means is to output the pressure of the first filtered water sent from the aforementioned first pure water unit as the detected pressure value; The first flow rate detection means is to output the flow rate of the first filtered water sent from the first pure water unit as the first detected flow rate value; The second pure water unit produces second filtered water from the first filtered water produced by the aforementioned first pure water unit; The supply target switching means is to switch the supply target of the first filtered water between the second pure water unit side and the discharge side; The second pump sends out the first filtered water to the second pure water unit; The second flow rate detection means is to output the flow rate of the second filtered water produced by the aforementioned second pure water unit as the second detected flow rate value; The first pump control unit drives the aforementioned first pump; The second pump control unit drives the aforementioned second pump; The switching means control unit makes the aforementioned supply target switching means switch; and Start the control section and perform the following steps in order: In the first step, when the second pure water unit is activated, in a state where the switching means control unit has been instructed to set the supply target switching means to the discharge side, the first pump control unit is instructed to enable the first Drive the aforementioned first pump in such a way that the detected flow value becomes the first target flow value; In the second step, the switching means control unit is caused to switch the supply target switching means to the second pure water unit side, and the first pump control unit is caused to drive the first pump at a fixed driving frequency; and In the third step, the first pump control unit drives the first pump so that the detected pressure value becomes the target pressure value, and the second detected flow value becomes the second target flow value. The second pump control unit drives the aforementioned second pump. The water treatment system described in claim 1, wherein the activation control unit is in the execution of the second step, and shifts to the third step when the detected pressure value is lower than the target pressure value Implementation. According to the water treatment system described in claim 1, wherein the activation control unit starts execution of the second step and then shifts to the execution of the third step after a predetermined time has passed. The water treatment system described in any one of items 1 to 3 of the scope of the patent application, wherein the fixed driving frequency falls within a predetermined threshold above the operable lower limit frequency of the first pump range.

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