Control method for a pure water production system and pure water production system

Abstract

To provide a control method for a pure water production system capable of controlling a water supply amount according to a water usage amount, in a pure water production system having a booster pump between water treatment devices.SOLUTION: When the water storage level in a pure water tank 111 measured by a level sensor 112 increases beyond the reference value, control means reduces the flow rate of primary pure water W2 supplied to the pure water tank 111 by throttling a flow control valve 113. Then, based on the measurement value of a second pressure gauge 115 upstream of the flow control valve 113, the output of a booster pump 109 is controlled to decrease the output of an inverter 110 so that the measurement value of the second pressure gauge 115 remains approximately constant at a predetermined pressure. Furthermore, the output of an inverter 103 for a delivery pump 102 is controlled to be decreased so that the pressure upstream of the booster pump 109 also remains substantially constant. This avoids the risk of cavitation in the booster pump 109, enabling stable operation of the booster pump 109 and supplying a required amount of primary pure water W2 to the pure water tank 111.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control method and a pure water production system for producing ultrapure water used in the electronics industry, such as semiconductors and liquid crystals, and more particularly to a control method and a pure water production system capable of controlling the water supply amount according to the amount of water used. [Background technology]

[0002] Traditionally, ultrapure water used in the electronics industry, such as semiconductors, is produced by treating raw water in an ultrapure water production system that consists of a pretreatment system, a primary pure water system, and a subsystem for processing the primary pure water.

[0003] For example, as shown in Figure 2, the ultrapure water production system 1 consists of three stages: a pretreatment device 2, a primary pure water device (pure water production system) 3, and a secondary pure water production device (subsystem) 4 as a pure water usage device. In the pretreatment device 2 of such an ultrapure water production system 1, the raw water W is pretreated by filtration, coagulation and sedimentation, and microfiltration membranes, mainly to remove suspended solids.

[0004] The primary pure water system 3 includes a water tank 31 for storing pre-treated water (water to be treated) W1, a water pump 32 for supplying the pre-treated water W1, a reverse osmosis membrane device 33, a membrane deaeration device 34 for removing dissolved gases with air, an ultraviolet oxidation device 35, an electro-regenerative deionizer 36, a regenerative ion exchange device 37, and a booster pump 38 for supplying water to the electro-regenerative deionizer 36. The primary pure water system 3 removes most of the electrolytes, fine particles, live bacteria, etc. from the pre-treated water W1 and decomposes organic matter.

[0005] Subsystem 4 consists of a sub-tank 41, which serves as a pure water tank located downstream of a regenerative ion exchange unit 38 that stores primary pure water W2 produced by the primary pure water unit 3; an ultraviolet oxidation unit 42, a non-regenerative mixed-bed ion exchange unit 43, and an ultrafiltration (UF) membrane 44 as a membrane filtration device, which process the primary pure water W2 supplied from the sub-tank 41 via a pump (not shown); and an RO membrane separation device, etc., may also be provided as needed. In this subsystem 4, the ultraviolet oxidation unit 42 oxidizes and decomposes trace amounts of organic matter (TOC components) contained in the primary pure water W2, and then the non-regenerative mixed-bed ion exchange unit 43 processes it to remove residual carbonate ions, organic acids, anionic substances, and even metal ions and cationic substances by ion exchange. Then, the ultrafiltration (UF) membrane 44 removes fine particles to produce ultrapure water W3, which is supplied to the use point 5, and the unused ultrapure water is returned to the sub-tank 41.

[0006] In this ultrapure water production system 1, in order to stably supply primary pure water of a predetermined quality, an excess amount of primary pure water W2 was produced in advance, and only the necessary amount was supplied to the sub-tank 41, with the surplus being recycled and reused.

[0007] However, with the conventional control method of the ultrapure water production system 1 described above, more water than necessary is supplied to the electro-regenerative deionizer 36 and other devices for processing, so there is room for improvement in terms of energy efficiency.Therefore, it is conceivable to vary the processing amount of the primary pure water device 3 in accordance with the amount used at use point 5, but this is not only difficult to keep up with the fluctuations in the amount used at use point 5, but it also leads to a decrease in the quality of the desalinated water produced by electro-deionization.

[0008] Therefore, as a control method for an ultrapure water production system capable of producing primary pure water according to the amount used at the point of use, the applicant has filed an application for a control method for a pure water production system (Japanese Patent Application No. 2023-035557), comprising a water supply source, a water supply mechanism connected to the water supply source, a water supply pressure gauge provided downstream of the water supply mechanism, and one or more types of water treatment equipment provided between the water supply mechanism and the pressure gauge, wherein the pure water produced by the pure water production system is supplied to a pure water user downstream of the pressure gauge, and a flow rate adjustment mechanism for the pure water supplied to the pure water user is provided between the pressure gauge and the pure water user, the flow rate adjustment mechanism adjusts the amount of pure water supplied according to the amount of water used by the pure water user, and controls the water supply output of the water supply mechanism so that the measured value of the pressure gauge is substantially constant.

[0009] The control method for this pure water production system can be implemented, for example, in a primary pure water device (pure water production system) 3 as shown in Figure 3. In Figure 3, the primary pure water device (pure water production system) 3 includes a water to be treated tank 51 as a water to be treated supply source for storing pre-treated water W1, a water supply pump 52A for the pre-treated water W1, an inverter-controllable high-pressure pump 52B for controlling the water supply output of the water supply pump 52A, a reverse osmosis membrane device 53, a first degassing membrane device 54A using air, a second degassing membrane device 54B using nitrogen gas, an ultraviolet oxidation device 55, an electro-regenerative deionizer (CDI) 56, and a water supply pump (boost pump) 57 for supplying water to the electro-regenerative deionizer 56. After the treated water from the electro-regenerative deionizer 56 is sent to a boron chelate resin tower 58 for treatment, primary pure water W2 can be supplied to subsystem 4.

[0010] In this primary pure water system 3, a pressure gauge 59 for the primary pure water W2 supplied to subsystem 4 and a flow control valve 60 as a flow control mechanism are provided downstream of the boron chelate resin tower 58. The pressure gauge 59 can transmit information to a control mechanism (not shown), which can inverter-control the high-pressure pump 52B so that the value measured by the pressure gauge 59 is approximately constant (for example, ±5% or less) relative to a predetermined value, and can also control the opening degree of the flow control valve 60 based on the amount of primary pure water W2 used in subsystem 4. The supply amount of primary pure water W2 can be controlled, for example, by measuring the supply amount of ultrapure water W3 from subsystem 4 to use point 5 using a flow meter, determining the amount of primary pure water W2 used according to this supply amount, and controlling the opening degree of the flow control valve 60. Alternatively, the supply amount of ultrapure water W3 from subsystem 4 to use point 5 and the return amount from use point 5 to subsystem 4 can be measured using flow meters, determining the amount of primary pure water W2 used according to the difference between the two, and controlling the opening degree of the flow control valve 60.

[0011] 61 is the recovery line for concentrated water from the reverse osmosis membrane device 53. This recovery line 61 is equipped with a flow control valve 62, a flow meter 63, a concentrated water tank 64, a water supply pump 65, and a recovery reverse osmosis membrane device 66. The treated water from the recovery reverse osmosis membrane device 66 is returned to the treated water tank 51. 67 is the recovery line for concentrated water from the electro-regenerative deionizer 56. This recovery line 67 is equipped with a flow control valve 68 and a flow meter 69. The concentrated water from the electro-regenerative deionizer 56 is sent to a dilute recovery reverse osmosis membrane (not shown) for treatment.

[0012] In such a primary pure water system (pure water production system) 3, the output of the high-pressure pump 52B is controlled so that the measured pressure of the pressure gauge 59 remains approximately constant, based on the amount of water supplied to pure water-using equipment such as the subsystem 4. This controls the amount of water supplied according to the amount of primary pure water W2 used by the subsystem 4 and the like. [Overview of the project] [Problems that the invention aims to solve]

[0013] The control method for the pure water production system described in Japanese Patent Application No. 2023-035557 makes it possible to produce primary pure water according to the amount used at the point of use. However, as a result of subsequent studies by the applicants, it was found that when water treatment equipment requiring water supply pressure is connected without a tank, as shown in Figure 3, in addition to the water supply pump 52A and high-pressure pump 52B from the water to be treated tank 51, one or more booster pumps 57 may be placed between the continuous water treatment equipment. In this case, if the water supply flow rate of only the water supply pump 52A or high-pressure pump 52B is controlled by an inverter, the pressure of the water supplied to the inlet side of the booster pump 57 decreases, which can cause cavitation in the booster pump 57 and potentially lead to failure.

[0014] The present invention has been made in view of the above problems, and aims to provide a control method for a pure water production system that has a booster pump between water treatment equipment, which can control the amount of water supplied according to the amount of water used, and a pure water production system that can implement this. [Means for solving the problem]

[0015] In view of the above objectives, the present invention first provides a control method for a pure water production system that supplies pure water produced by a pure water production system to a pure water using device, comprising a water to be treated supply source, a water supply mechanism connected to the water to be treated supply source, two or more types of water treatment devices provided downstream of the water supply mechanism, a first pressure gauge provided in the middle of the water treatment devices, a booster pump provided downstream of the first pressure gauge and in the middle of the two or more types of water treatment devices, a flow rate adjustment mechanism for pure water supplied to a pure water using device provided downstream of the water treatment devices and a second pressure measuring means provided downstream of the water treatment devices and in the flow rate adjustment mechanism, wherein the amount of pure water supplied by the flow rate adjustment mechanism is adjusted according to the amount of water used by the pure water using device, the water flow rate of the booster pump is controlled so that the measured value of the second pressure measuring means is substantially constant, and the water supply output of the water supply mechanism is controlled so that the measured value of the first pressure gauge is substantially constant (Invention 1).

[0016] According to this invention (Invention 1), the amount of pure water supplied is adjusted by the flow rate adjustment mechanism according to the amount of pure water used by the equipment using pure water. At this time, the water flow rate of the booster pump is controlled so that the measured value of the second pressure measuring means becomes approximately constant, and the water supply output of the water supply mechanism is controlled so that the measured value of the first pressure gauge becomes approximately constant. As a result, the pressure of the water supplied to the inlet side of the booster pump does not fluctuate much, and the risk of cavitation occurring in the booster pump can be suppressed. Furthermore, the operating pressure of the water treatment equipment located downstream of the booster pump can be stabilized.

[0017] In the above invention (Invention 1), it is preferable that the water treatment equipment is one or more selected from a reverse osmosis membrane device, a membrane degasser, an ultraviolet oxidation device, an electroregenerative deionizer, a non-regenerative ion exchange device, and a UF membrane device (Invention 2).

[0018] According to this invention (Invention 2), it becomes possible to apply it to various general-purpose pure water production systems.

[0019] In the above inventions (Inventions 1 and 2), it is preferable that the water supply flow rate of the booster pump is controlled by the frequency output from the inverter, and the lower limit value of the variation value of the water consumption of the pure water using equipment is 50% or more with respect to the maximum value (Invention 3).

[0020] According to such an invention (Invention 3), by controlling the water supply flow rate of the booster pump by inverter control, it is possible to quickly and widely respond to the amount of water corresponding to the variation in the water consumption of the pure water using equipment.

[0021] Secondly, the present invention further provides a pure water production system comprising a source of treated water, a water supply mechanism connected to the source of treated water, two or more types of water treatment equipment provided downstream of the water supply mechanism, a first pressure gauge provided in the middle of the water treatment equipment, having a booster pump in the middle of the two or more types of water treatment equipment downstream of the first pressure gauge, having a flow rate adjustment mechanism for the pure water supplied to the pure water using equipment in the front stage of the pure water using equipment provided downstream of the water treatment equipment, and having a second pressure measuring means in the front stage of the flow rate adjustment mechanism downstream of the water treatment equipment. The pure water production system adjusts the supply amount of pure water by the flow rate adjustment mechanism according to the water consumption of the pure water using equipment, controls the water supply flow rate of the booster pump so that the measured value of the second pressure measuring means becomes substantially constant, and controls the water supply output of the water supply mechanism so that the measured value of the first pressure gauge becomes substantially constant (Invention 4).

[0022] According to such an invention (Invention 4), according to the water consumption of the pure water using equipment, the supply amount of pure water is adjusted by the flow rate adjustment mechanism. At this time, the water supply flow rate of the booster pump is controlled so that the measured value of the second pressure measuring means becomes substantially constant, and the water supply output of the water supply mechanism is controlled so that the measured value of the first pressure gauge becomes substantially constant. Therefore, by reducing the fluctuation of the pressure of the water supplied to the inlet side of the booster pump, the risk of cavitation generation during boosting can be suppressed. Furthermore, the operating pressure of the water treatment equipment arranged downstream of the booster pump can be stabilized.

[0023] In the above invention (Invention 4), it is preferable that the water treatment equipment is one or more selected from a reverse osmosis membrane device, a membrane degassing device, an ultraviolet oxidation device, an electrically regenerative deionization device, a non-regenerative ion exchange device, and a UF membrane device (Invention 5).

[0024] According to such an invention (Invention 5), it becomes possible to apply to various general pure water production systems.

[0025] In the above inventions (Inventions 4 and 5), it is preferable that the water supply flow rate of the booster pump is controlled by the frequency output from the inverter, and the lower limit value of the fluctuation value of the water consumption of the pure water using equipment is 50% or more with respect to the maximum value (Invention 6).

[0026] According to such an invention (Invention 6), by controlling the water supply flow rate of the booster pump by inverter control, it is possible to quickly respond to fluctuations in the water consumption of the pure water using equipment and handle a wide range of water volumes.

Effects of the Invention

[0027] According to the control method of the pure water production system of the present invention, according to the water consumption of the pure water using equipment, the supply amount of pure water is adjusted by the flow rate adjustment mechanism, and the water supply flow rate of the booster pump is controlled so that the measured value of the second pressure measuring means becomes substantially constant. At the same time, the water supply output of the water supply mechanism is controlled so that the measured value of the first pressure gauge becomes substantially constant. Therefore, the risk of cavitation during pressurization can be suppressed. Furthermore, the operating pressure of the water treatment equipment arranged downstream of the booster pump can be stabilized.

Brief Description of the Drawings

[0028] [Figure 1] It is a flowchart showing a pure water production system according to an embodiment of the present invention. [Figure 2] It is a flowchart showing an ultrapure water production system equipped with a pure water production system. [Figure 3] It is a flowchart showing a conventional pure water production system.

Modes for Carrying Out the Invention

[0029] The pure water production system and its control method of the present invention will be described below with reference to the attached drawings.

[0030] (Pure water production system) The pure water production system (primary pure water system) of this embodiment can be applied to various pure water production systems as long as it includes a water supply pump for supplying water to be treated, two or more types of water treatment equipment, a booster pump installed between these water treatment equipment, and a pure water usage device installed downstream of the two or more types of water treatment equipment for using the produced pure water. For example, it can be suitably applied to an ultrapure water production system as shown in Figure 1.

[0031] In Figure 1, the primary pure water system (pure water production system) 3 includes a water tank 101 as a water supply source for storing pre-treated water W1, a water pump 102 for supplying the pre-treated water W1, an inverter 103 for controlling the water supply output of the water pump 102, and water treatment equipment including a reverse osmosis membrane system (RO membrane system) 104, a membrane degasser 105, an ultraviolet oxidation system 106, an electro-regenerative deionizer (CDI) 107, and a regenerative ion exchange resin tower 108. A booster pump 109 equipped with an inverter 110 for supplying water to the electro-regenerative deionizer 107 is provided upstream of the electro-regenerative deionizer 107, i.e., in the middle of the water treatment equipment. The primary pure water W2 treated in the ion exchange resin tower 108 is stored in a pure water tank 111 such as a sub-tank.

[0032] In this primary pure water system 3, a level sensor 112 is attached to the pure water tank 111, and a flow control valve 113 is provided upstream of the pure water tank 111. The level sensor 112 can transmit information to a control means (not shown), and this control means can adjust the amount of water supplied to the pure water tank 111 by controlling the flow control valve 113 according to the measured value of the level sensor 112. In addition, a first pressure gauge 114 is provided upstream of the booster pump 109, and this first pressure gauge 114 can transmit information to a control mechanism (not shown), and this control mechanism can inverter-control the water supply pump 102 so that the measured value from the first pressure gauge 114 is approximately constant (for example, ±5% or less) relative to a predetermined value. Furthermore, a second pressure gauge 115 is provided upstream of the flow control valve 113. This second pressure gauge 115 can transmit information to a control mechanism (not shown), which can inverter-control the boost pump 109 so that the value measured by the second pressure gauge 115 remains approximately constant (for example, within ±5%) of a predetermined value.

[0033] (Control method for a pure water production system) Next, we will explain the control method for the pure water production system shown in Figure 1. In Figure 1, a water supply pump 102 equipped with an inverter 103 is started to supply pre-treated water (water to be treated) W1 from the water to be treated tank 101, and the water is treated in a reverse osmosis membrane device 104, a membrane degasser 105, and an ultraviolet oxidation device 106. The feedwater is then pressurized by a booster pump 109 and treated in an electro-regenerative deionizer (CDI) 107 and a regenerative ion exchange resin tower 108, after which the resulting primary pure water W2 is stored in a pure water tank 111.

[0034] At this time, a reference value (which may be a value within a predetermined range) for the water level of the sub-tank 11 is set in advance, and the increase or decrease of this value is linked to the amount of water used by the equipment that uses pure water. In addition, the water supply pressure before the flow control valve 113 (measured value of the second pressure gauge 115) and the pressure before the booster pump 109 (measured value of the first pressure gauge 114) are also set in advance.

[0035] Then, if the amount of water stored in the pure water tank 111, as measured by the level sensor 112, increases above a standard value due to a decrease in water usage at use points, etc., a control means (not shown) restricts the flow control valve 113 to reduce the amount of primary pure water W2 supplied to the pure water tank 111. As a result, the water supply pressure measured by the second pressure gauge 115 tends to rise, but the output of the booster pump 109 is controlled to decrease the output of the inverter 110 (frequency; Hz, the same applies hereinafter) so that the measured value of the second pressure gauge 115 remains approximately constant at a predetermined pressure. In addition, the output of the inverter 103 of the water supply pump 102 is controlled to decrease so that the pressure upstream of the booster pump 109 (measured value of the first pressure gauge 114) also remains approximately constant. As a result, the water supply pressure on the inlet side of the booster pump 109 does not decrease, thus avoiding the risk of cavitation in the booster pump 109, allowing the booster pump 109 to operate stably and supplying the required amount of primary pure water W2 to the pure water tank 111.

[0036] On the other hand, if the amount of water used at the use point increases and the amount of water stored in the pure water tank 111, as measured by the level sensor 112, falls below the standard value, a control means (not shown) opens the flow control valve 113 to increase the amount of primary pure water W2 supplied to the pure water tank 111. As a result, the water supply pressure measured by the second pressure gauge 115 tends to decrease, but the inverter 110 controls the booster pump 109 to increase its output so that the measured value of the second pressure gauge 115 remains approximately constant at a predetermined pressure. In addition, the inverter 103 controls the water supply pump 102 to increase its output so that the pressure upstream of the booster pump 109 (measured by the first pressure gauge 114) also remains approximately constant. This allows the water supply pressure of the booster pump 109 to be maintained at approximately constant levels, enabling stable operation of the booster pump 109 and supplying the required amount of primary pure water W2 to the pure water tank 111. In this control method for the pure water production system, it is preferable that the lower limit of the fluctuation value of the amount of water used by the pure water-using equipment is 50% or more of the maximum value (100%).

[0037] Although the present invention has been described above based on the above embodiments, the present invention is not limited to the above embodiments and can be implemented in various modified forms. For example, there are no particular restrictions on the two or more types of water treatment equipment, and it can be composed of two or more types selected from reverse osmosis membranes, ultraviolet oxidation devices, degassing membranes, electro-regenerative deionization devices, regenerative ion exchange devices, and non-regenerative ion exchange devices. In addition, although control is performed based on the water level of the pure water tank 111 in the above embodiment, a flow meter may be provided at the outlet of the pure water tank 111 and control may be performed based on the amount of primary pure water W2 supplied from the pure water tank 111. Furthermore, although the water supply mechanism is configured with only a water supply pump 102 as in this embodiment, it may also be configured as a two-stage system with a water supply pump and an inverter-controllable high-pressure pump to control the water supply output of this water supply pump. [Examples]

[0038] The present invention will be described more specifically based on the following examples, but the present invention is not limited to the following examples.

[0039] [Example 1] Using the pure water production system shown in Figure 1, 3m 3 Pre-treated water W1 was supplied from a water tank (pre-treatment tank) 101, which can hold a certain amount of liquid, to a reverse osmosis membrane device 104 by a water pump 102 equipped with an inverter 103. For the reverse osmosis membrane device 104, when the effective membrane pressure was 0.6 MPa, approximately 0.7 m 3 / m 2 An ultra-low pressure membrane was used to obtain a permeate rate of / day. The permeate obtained from the reverse osmosis membrane apparatus 104 had dissolved gases removed in the membrane deaeration apparatus 105, and organic components were decomposed in the ultraviolet oxidation apparatus 106. Then, the water pressure was increased by the booster pump 109 and the water was passed through the electro-regenerative deionization apparatus 107. Residual ions in the treated water from the electro-regenerative deionization apparatus 107 were removed in the regenerative ion exchange resin tower 108 to obtain primary pure water W2, which was then passed through the flow control valve 113 to 3m 3 The water was then sent to a pure water tank 111, which could hold a certain volume of liquid. This primary pure water W2 was further sent from the pure water tank 111 to the polishing process by a water pump to become ultrapure water, which was then used at the point of use.

[0040] The flow rate adjustment valve 113 was controlled so that the level of the pure water tank 111 would be constant. The water delivery rate of the water delivery pump 102 was set to 50 Hz for the frequency output from the inverter 103 so as to be a maximum of 30 m 3 / hr. A constant flow rate valve was installed in the brine water passage line so that the brine water volume from the reverse osmosis membrane device 104 would be constant at about 6 m 3 / hr. The booster pump 109 used a type with a required suction head of 0.1 MPa, and the water delivery rate of the booster pump 109 was adjusted for the frequency output from the inverter 110 so that the pressure at the front stage of the flow rate adjustment valve 113 (measurement value of the second pressure gauge 115) would be 0.1 MPa at a maximum of 24 m 3 / hr, and as a result, it became 48 Hz. At this time, the inlet side pressure of the booster pump 109 was 0.2 MPa. A constant flow rate valve was installed in the brine water passage line so that the brine water volume in the electrically regenerative deionizer 107 would be about 1 m 3 / hr.

[0041] In such a pure water production system, while controlling the inverter 110 of the booster pump 109 so that the pressure at the front stage of the flow rate adjustment valve 113 (measurement value of the second pressure gauge 115) would be substantially constant at 0.1 MPa, and controlling the inverter 103 of the water delivery pump 102 so that the pressure at the front stage of the booster pump 109 (measurement value of the first pressure gauge 114) would be substantially constant at 0.2 MPa, the amount of ultrapure water used at the use point was reduced, and the water delivery rate from the pure water tank 111 was reduced from a maximum of about 23 m 3 / hr to about 12 m 3 / hr (52%). As a result, the input frequency of the booster pump 109 decreased to about 26 to 30 Hz, and the input frequency of the water delivery pump 102 decreased to about 32 to 36 Hz. At this time, since the front stage pressure of the booster pump 109 was maintained at 0.2 MPa, the cavitation risk in the booster pump 109 could be avoided.

[0042] [Comparative Example 1] In Example 1, the inverter 103 of the water supply pump 102 was controlled so that the pressure upstream of the flow control valve 113 (measured by the second pressure gauge 115) remained approximately constant at 0.1 MPa. The boost pump 109 was not controlled by the inverter 110 and operated at a constant 48 Hz, reducing the amount of ultrapure water used at the point of use, and the amount of water supplied from the pure water tank 111 was increased to a maximum of approximately 23 m³. 3 From / hr, approximately 12m 3 The rate was reduced to 52% per hour. As a result, the inlet frequency in the water supply pump 102 decreased to approximately 32-36 Hz, but the upstream pressure in the booster pump 109 dropped to approximately 0.1 MPa, resulting in an operating condition where cavitation was at risk in the booster pump 109. [Explanation of symbols]

[0043] 1. Ultrapure water production system 2 Pre-treatment device 3. Primary pure water system (pure water production system) 4. Secondary pure water production system (subsystem) 5. Use Points (Equipment using pure water) 101 Water to be treated tank (source of water to be treated) 102 Water supply pump (water supply mechanism) 103 Inverter 104 Reverse osmosis membrane system (water treatment equipment) 105 Membrane-type degassing device (water treatment equipment) 106 Ultraviolet oxidation equipment (water treatment equipment) 107 Electro-regenerative deionizer (CDI) (Water treatment equipment) 108 Regenerative ion exchange resin tower (water treatment equipment) 109 Booster pump 110 Inverter 111 Pure water tank 112 Level Sensor 113 Flow control valve (flow control mechanism) 114 First pressure gauge 115 Second pressure gauge W Raw Water W1 Pre-treated water (water to be treated) W2 Primary pure water (pure water) W3 Secondary Purified Water (Ultrapure Water)

Claims

1. The system comprises a water supply source, a water supply mechanism connected to the water supply source, two or more types of water treatment equipment located downstream of the water supply mechanism, and a first pressure gauge located between the two or more types of water treatment equipment. A control method for a pure water production system comprising: a booster pump installed downstream of the first pressure gauge and intermediate between the two or more types of water treatment equipment; a flow rate adjustment mechanism for pure water supplied to a pure water user installed upstream of a pure water user installed downstream of the two or more types of water treatment equipment; and a second pressure gauge installed downstream of the two or more types of water treatment equipment and upstream of the flow rate adjustment mechanism, wherein The control method involves supplying the pure water produced by the pure water production system to the equipment that uses the pure water. The amount of pure water supplied is adjusted by the flow rate adjustment mechanism according to the amount of pure water used by the pure water equipment. A control method for a pure water production system, comprising: controlling the water flow rate of the booster pump so that the measured value of the second pressure gauge is within ±5% of a predetermined value; and controlling the water supply output of the water supply mechanism so that the measured value of the first pressure gauge is within ±5% of a predetermined value.

2. A control method for a pure water production system according to claim 1, wherein the water treatment equipment is two or more selected from a reverse osmosis membrane device, a membrane degasser, an ultraviolet oxidation device, an electroregenerative deionizer, and a regenerative ion exchange device.

3. A control method for a pure water production system according to claim 1 or 2, wherein the water flow rate of the booster pump is controlled by the frequency output from the inverter, and the lower limit of the fluctuation value of the amount of water used by the pure water equipment is 50% or more of the maximum value.

4. The system comprises a water supply source, a water supply mechanism connected to the water supply source, two or more types of water treatment equipment located downstream of the water supply mechanism, and a first pressure gauge located between the two or more types of water treatment equipment. The system includes a booster pump located downstream of the first pressure gauge and intermediate between the two or more water treatment devices, a flow rate adjustment mechanism for pure water supplied to the pure water user located upstream of the pure water user located downstream of the two or more water treatment devices, and a second pressure gauge located downstream of the two or more water treatment devices and upstream of the flow rate adjustment mechanism. A pure water production system having control means for adjusting the amount of pure water supplied by the flow rate adjustment mechanism according to the amount of pure water used by the pure water equipment, controlling the water flow rate of the booster pump so that the measured value of the second pressure gauge is within ±5% of a predetermined value, and controlling the water supply output of the water supply mechanism so that the measured value of the first pressure gauge is within ±5% of a predetermined value.

5. The pure water production system according to claim 4, wherein the water treatment equipment is two or more selected from a reverse osmosis membrane device, a membrane degasser, an ultraviolet oxidation device, an electroregenerative deionizer, and a regenerative ion exchange device.

6. The pure water production system according to claim 4 or 5, wherein the control means controls the water flow rate of the booster pump by the frequency output from the inverter, and the lower limit of the fluctuation value of the amount of water used by the pure water equipment is 50% or more of the maximum value.

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