Water treatment equipment, control device, operation method and program

Abstract

To finely adjust the amount of treated water supplied without deteriorating the quality of the treated water. [Solution] The system includes water treatment devices 205-1 to 205-4 arranged in parallel with each other, pumps 204-1 to 204-4 that supply water to be treated to each of the water treatment devices 205-1 to 205-4, and a control device 220 that controls the operation of pumps 204-1 to 204-4 and water treatment devices 205-1 to 205-4 so that the flow rate of treated water flowing out of each of the water treatment devices 205-1 to 205-4 is the required flow rate according to the amount of treated water supplied from the water treatment devices 205-1 to 205-4 to a destination.

Description

[Technical Field]

[0001] The present invention relates to a water treatment facility, a control device, an operation method, and a program. [Background technology]

[0002] At a point of use where treated water treated by a water treatment system is used, the amount of treated water required at that point of use is supplied. The amount of treated water required at a point of use is not fixed. Therefore, water treatment systems are designed to supply an amount of treated water according to the amount of use. For example, a technology has been disclosed in which the discharge rate of a supply pump that supplies raw water to an RO module that purifies the purified water is controlled according to the consumption rate of purified water, which is the treated water (see, for example, Patent Document 1). Also disclosed is an apparatus for obtaining pure water using two reverse osmosis membrane modules arranged in parallel, in which the operation of one of the reverse osmosis membrane modules is stopped according to the amount of pure water used (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-104639 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-187446 Summary of the Invention [Problem to be solved by the invention]

[0004] In general, in water treatment devices such as reverse osmosis membrane modules, where the quality of treated water decreases as the flow rate decreases, there is a problem that the quality of the treated water supplied decreases when control is performed using the technology described in Patent Document 1 when the amount of treated water used is small. Also, as described in Patent Document 2, there is a problem that it is difficult to make fine adjustments to the flow rate when controlling the number of modules performing treatment.

[0005] An object of the present invention is to provide a water treatment facility, a control device, an operating method, and a program that are capable of finely adjusting the amount of treated water supplied without deteriorating the quality of the treated water. [Means for solving the problem]

[0006] The water treatment facility of the present invention comprises: A plurality of water treatment devices arranged in parallel with each other; a plurality of pumps that supply water to be treated to each of the plurality of water treatment devices; The system includes a control device that controls the operation of the multiple pumps and the multiple water treatment devices so that the flow rate of treated water flowing out of each of the multiple water treatment devices is the required flow rate according to the amount of treated water supplied from the multiple water treatment devices to a destination.

[0007] The control device of the present invention also includes: an acquisition unit that acquires a plurality of flow rate values ​​that indicate the flow rate of treated water flowing out from each of a plurality of water treatment devices that are arranged in parallel with each other; The system includes a control unit that controls a plurality of pumps that supply treated water to each of the plurality of water treatment devices and the operation of the plurality of water treatment devices so that the flow rate indicated by the plurality of flow rate values ​​acquired by the acquisition unit is the required flow rate according to the amount of treated water supplied from the plurality of water treatment devices to the supply destination.

[0008] Further, the operating method of the present invention includes the steps of: A process of acquiring a plurality of flow rate values ​​indicating the flow rate of treated water flowing out from each of a plurality of water treatment devices arranged in parallel with each other; A process is performed to control the operation of multiple pumps that supply treated water to each of the multiple water treatment devices and the multiple water treatment devices so that the flow rate indicated by the multiple flow rate values ​​becomes the required flow rate corresponding to the amount of treated water supplied from the multiple water treatment devices to the supply destination.

[0009] The program of the present invention also includes: On the computer, acquiring a plurality of flow rate values ​​indicating the flow rate of treated water flowing out of each of a plurality of water treatment devices arranged in parallel with one another; A procedure is executed to control multiple pumps that supply treated water to each of the multiple water treatment devices and the operation of the multiple water treatment devices so that the flow rate indicated by the multiple flow rate values ​​becomes the required flow rate corresponding to the amount of treated water supplied from the multiple water treatment devices to the supply destination. [Effects of the Invention]

[0010] In the present invention, the amount of treated water supplied can be finely adjusted without deteriorating the quality of the treated water. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing an example of a water treatment system to which the water treatment facility according to the present invention is applied. [Figure 2] FIG. 2 is a diagram showing a first embodiment of a primary pure water manufacturing system that is applied to the water treatment system shown in FIG. [Figure 3] 3 is a diagram illustrating an example of components included in the control device illustrated in FIG. 2. FIG. [Figure 4] 3 is a diagram for explaining an example of processing by the control device shown in FIG. 2 in chronological order. FIG. [Figure 5] 3 is a diagram for explaining an example of processing by the control device shown in FIG. 2 in chronological order. FIG. [Figure 6] 3 is a flowchart illustrating an example of a process performed when the amount of treated water supplied to a supply destination decreases, among the operating methods of the control device shown in FIG. 2. [Figure 7] 3 is a flowchart illustrating an example of a process performed when the amount of treated water supplied to a supply destination increases, among the operating methods of the control device shown in FIG. 2. [Figure 8] FIG. 2 is a diagram showing a second embodiment of a primary pure water manufacturing system that is applied to the water treatment system shown in FIG. [Figure 9] 9 is a diagram illustrating an example of components included in the control device illustrated in FIG. 8. FIG. [Figure 10] 9 is a diagram for explaining an example of processing of the control device shown in FIG. 8 in chronological order. [Figure 11] 9 is a flowchart illustrating an example of a process performed when the amount of treated water supplied to a supply destination increases, among the operating methods of the control device shown in FIG. 8. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] FIG. 1 is a diagram showing an example of a water treatment system to which the water treatment equipment of the present invention is applied. The water treatment system shown in FIG. 1 includes a pretreatment system 10, a primary pure water production system 20, and a subsystem 30. The pretreatment system 10 may be a system used in a general water treatment system and is a water treatment equipment that removes impurities such as turbidity and TOC (total organic carbon) so that treated water of suitable quality can be supplied to downstream equipment. The primary pure water production system 20 is a water treatment equipment that performs a predetermined treatment on the treated water treated in the pretreatment system 10 and supplies the treated water to the subsystem 30. The subsystem 30 may be a secondary pure water production system used in a general water treatment system and is a water treatment equipment that removes trace amounts of ions and total organic carbon that were not completely removed in the primary pure water production system 20. The water treatment equipment of the present invention can be used for pure water production, ultrapure water production, wastewater recovery, sewage reuse, and seawater desalination. In particular, the water treatment equipment of the present invention is suitable for pure water production and ultrapure water production, which require high-purity water quality. (First embodiment)

[0014] Fig. 2 is a diagram showing a first embodiment of a primary pure water producing system 20 that can be applied to the water treatment system shown in Fig. 1. As shown in Fig. 2, the primary pure water producing system 20 that can be applied to the water treatment system shown in Fig. 1 includes an RO raw water tank 200, pumps 201, 204-1 to 204-4, and 212, a filter 202, on-off valves 203, 207 to 209, and 217, reverse osmosis (RO) membrane separation (RO) devices 205-1 to 205-4, flow meters 206-1 to 206-4, 214-1 to 214-4, and 215, an EDI raw water tank 210, a water level gauge 211, electrodeionized water producing devices 213-1 to 213-4, a demineralized water tank 216, and a control device 220. Note that Fig. 2 shows only the main components related to this embodiment among the components of the primary pure water producing system 20 shown in Fig. 1. For example, a water treatment device such as an ultraviolet oxidation device that irradiates ultraviolet light onto the water to be treated and decomposes organic matter contained in the water may be provided upstream of the electrodeionized water production devices 213-1 to 213-4. Also, a water treatment device such as a membrane degassing device that removes dissolved gases such as oxygen and carbon dioxide may be provided upstream or downstream of the electrodeionized water production devices 213-1 to 213-4.

[0015] The RO raw water tank 200 is a water tank in which the liquid (water to be treated) treated in the pretreatment system 10 is stored.

[0016] The pump 201 pumps up the water to be treated stored in the RO raw water tank 200 and supplies it to the filter 202. The pump 201 is provided with an inverter, and the drive frequency of the pump 201 is controlled by controlling the inverter, thereby controlling the discharge rate (the amount of water supplied to the filter 202). The filter 202 removes impurities from the water to be treated supplied from the pump 201.

[0017] Pumps 204-1 to 204-4 are provided on each of the four parallel branch paths that branch from filter 202. Pumps 204-1 to 204-4 supply the water to be treated that has passed through filter 202 to reverse osmosis membrane separation devices 205-1 to 205-4, respectively, that are provided on the respective branch paths. Each of pumps 204-1 to 204-4 is provided with an inverter device that adjusts the supply amount. Open / close valve 203 is provided on the branch path to pump 204-1 and controls the supply of water to pump 204-1. Open / close valve 208 controls the supply of treated water treated by reverse osmosis membrane separation device 205-1 to EDI raw water tank 210. By controlling open / close valves 203 and 208, reverse osmosis membrane separation device 205-1 can be isolated.

[0018] The reverse osmosis membrane separation devices 205-1 to 205-4 are water treatment devices disposed on respective branch paths that branch in parallel from the RO raw water tank 200. The reverse osmosis membrane separation devices 205-1 to 205-4, for example, separate ions and TOC from the water to be treated supplied from the pumps 204-1 to 204-4, respectively, and divide the water to be treated into permeate and concentrate. In this embodiment, the reverse osmosis membrane separation devices 205-1 to 205-4 are preferably devices that operate at a constant recovery rate, which is the ratio of the amount of permeate to the amount of feed water. The recovery rate in the reverse osmosis membrane separation devices 205-1 to 205-4 is controlled to a constant rate using an inverter or a pressure regulating valve (not shown) installed in the reverse osmosis membrane concentration line. When the recovery rate is controlled to a constant rate, the quality of the treated water (permeate) decreases as the amount of the resulting treated water decreases. A water treatment device having such properties (for example, an electrodeionized water production device) may be disposed in place of each of the reverse osmosis membrane separation devices 205-1 to 205-4.

[0019] The reverse osmosis membrane separation devices 205-1 to 205-4 in this embodiment usually have a capacity of 1.0 m per 8-inch RO membrane for pure water production, although this depends on the quality of the raw water. 3The RO membrane is operated at a permeate rate of about 0.5 m / h, depending on the components of the membrane (sodium, etc.). 3 / h, the quality of the treated water will be significantly reduced. When each of the reverse osmosis membrane separation devices 205-1 to 205-4 is composed of three RO membranes, the permeate volume of each of the reverse osmosis membrane separation devices 205-1 to 205-4 is 1.5 m 3 It is necessary to control it so that it does not fall below / h.

[0020] The flow meters 206-1 to 206-4 measure the flow rate of the treated water (permeated water) flowing out of the reverse osmosis membrane separation devices 205-1 to 205-4, respectively. The flow meters 206-1 to 206-4 notify the control device 220 of the measured value.

[0021] The on-off valve 207 is an on-off valve that switches the flow path between returning a portion or all of the combined treated water flowing out from the reverse osmosis membrane separation device 205-1 to the RO raw water tank 200 via a circulation path to the RO raw water tank 200 or to a path to the EDI raw water tank 210. The on-off valve 207 is a three-way valve. Such a three-way valve that switches the flow path between returning the treated water to the RO raw water tank 200 via a circulation path to the RO raw water tank 200 or to a path to the EDI raw water tank 210 may be provided at the outlet of each of the reverse osmosis membrane separation devices 205-2 to 205-4. The on-off valve 209 is an on-off valve that supplies a portion or all of the combined treated water flowing out from each of the reverse osmosis membrane separation devices 205-1 to 205-4 to the EDI raw water tank 210. By controlling the opening and closing of on-off valve 207 and on-off valve 209, it is controlled whether the treated water flowing out from each of the reverse osmosis membrane separation devices 205-1 to 205-4 is supplied to EDI raw water tank 210 or returned to RO raw water tank 200. In addition, by controlling the opening and closing of on-off valve 217 provided in a path returning the treated water flowing out from each of the reverse osmosis membrane separation devices 205-1 to 205-4 to the RO raw water tank 200 and on-off valve 209 provided in a path supplying the treated water flowing out from each of the reverse osmosis membrane separation devices 205-1 to 205-4 to the EDI raw water tank 210, it is controlled whether the treated water flowing out from each of the reverse osmosis membrane separation devices 205-1 to 205-4 is supplied to EDI raw water tank 210 or returned to RO raw water tank 200. Furthermore, by controlling the opening of the on-off valve 217, a portion of the treated water flowing out from each of the reverse osmosis membrane separation devices 205-1 to 205-4 is returned to the RO raw water tank 200. By circulating a portion of the treated water, the quality of the treated water can be further stabilized.

[0022] EDI raw water tank 210 is a water tank that stores treated water obtained after the treated water from each of reverse osmosis membrane separation devices 205-1 to 205-4 joins together. Water level meter 211 is a level sensor that measures the level of the treated water stored in EDI raw water tank 210. Water level meter 211 notifies control device 220 of the measured water level value. Pump 212 supplies the treated water stored in EDI raw water tank 210 to each of electrodeionized water production devices 213-1 to 213-4.

[0023] Each electrodeionized water production apparatus 213-1 to 213-4 is provided on one of four parallel branch paths extending from pump 212. Each electrodeionized water production apparatus 213-1 to 213-4 is a typical EDI apparatus (electrodeionized water production apparatus) having a deionization compartment, a concentration compartment, and an electrode compartment, separated by cation exchange membranes and anion exchange membranes. A direct current is passed through each electrodeionized water production apparatus 213-1 to 213-4, and ions contained in the treated water supplied to each electrodeionized water production apparatus 213-1 to 213-4 are removed within the deionization compartment, while the ion exchange resin is continuously regenerated. The treated water from which ions have been removed in each electrodeionized water production apparatus 213-1 to 213-4 is discharged as deionized water. Meanwhile, a portion of the water to be treated is sent to the concentration compartments of the electrodeionized water production devices 213-1 to 213-4, and is discharged from the electrodeionized water production devices 213-1 to 213-4 as concentrated water with concentrated ions.

[0024] Each of flow meters 214-1 to 214-4 measures the flow rate of treated water (demineralized water) flowing out of the deionization compartment (pure water compartment) of each of electrodeionized water production apparatuses 213-1 to 213-4. Each of flow meters 214-1 to 214-4 notifies control device 220 of the measured value. Flow meter 215 measures the flow rate of treated water that has been treated in each of electrodeionized water production apparatuses 213-1 to 213-4 and merged from the branched paths. Flow meter 215 notifies control device 220 of the measured value. Note that instead of flow meters 214-1 to 214-4, the control device 220 may be notified of the flow rate of the treated water calculated using, for example, the measurement results of a pressure gauge that measures the pressure of the treated water, the output value of an inverter of a pump that sends the treated water, or the aperture value of a valve that controls the flow of the treated water. That is, there are no particular limitations on the means for measuring or calculating the flow rate of the treated water that has been treated in each of the electrodeionized water production apparatuses 213-1 to 213-4 and then joined through the branched paths.

[0025] The demineralized water tank 216 is a water tank that stores treated water that has been treated in each of the electrodeionized water production devices 213-1 to 213-4 and then merges from the branched paths.

[0026] 2 shows an example in which the number of branch paths to the reverse osmosis membrane separators 205-1 to 205-4 and the number of branch paths to the electrodeionized water production devices 213-1 to 213-4 are four, but this number is not particularly limited. Also, while FIG. 2 shows an example in which the number of reverse osmosis membrane separators provided in each branch path from the filter 202 to the EDI raw water tank 210 is one, this number may also be two, and is not particularly limited. Specifically, multiple reverse osmosis membrane separators may be arranged in series between each of the pumps 204-1 to 204-4 and each of the flow meters 206-1 to 206-4.

[0027] The control device 220 controls the opening and closing of the pumps 204-1 to 204-4 and the on-off valves 203 and 208 or the operation of the reverse osmosis membrane separation device 205-1 based on the flow rate values ​​notified from the flow meters 206-1 to 206-4 and the water level value notified from the water level meter 211. FIG. 3 is a diagram showing an example of components included in the control device 220 shown in FIG. 2. As shown in FIG. 3, the control device 220 shown in FIG. 2 has an acquisition unit 230 and a control unit 240. Note that FIG. 3 shows main components according to this embodiment among the components included in the control device 220 shown in FIG. 2.

[0028] The acquiring unit 230 acquires the flow rate values ​​notified from each of the flow meters 206-1 to 206-4. If another flow meter is provided between the RO raw water tank 200 and the pump 212, the acquiring unit 230 may acquire the measurement value from that flow meter. The acquiring unit 230 also acquires the water level value notified from the water level meter 211. The acquiring unit 230 also acquires the flow rate values ​​notified from each of the flow meters 214-1 to 214-4. The acquiring unit 230 also acquires the flow rate value notified from the flow meter 215. The acquiring unit 230 notifies the control unit 240 of the acquired values.

[0029] The control unit 240 calculates the required flow rate of treated water to be supplied from the reverse osmosis membrane separation devices 205-1 to 205-4 to the supply destination based on the water level value acquired by the acquisition unit 230 from the water level meter 211. Specifically, the control unit 240 calculates the required flow rate of treated water required (used) by the supply destination based on a change in the water level value acquired by the acquisition unit 230 from the water level meter 211. For example, if the water level value acquired by the acquisition unit 230 from the water level meter 211 is rising, the amount of treated water used at the supply destination is decreasing. Therefore, the control unit 240 calculates the decreased required flow rate of treated water to be supplied from the reverse osmosis membrane separation devices 205-1 to 205-4 to the supply destination based on the increase in the water level value. Furthermore, if the water level value acquired by the acquisition unit 230 from the water level meter 211 is decreasing, the amount of treated water used at the supply destination is increasing. Therefore, the control unit 240 calculates the required flow rate of the increased treated water to be supplied from the reverse osmosis membrane separation apparatuses 205-1 to 205-4 to the supply destination based on the amount of decrease in the water level value. The required flow rate may be calculated using proportional control that increases the flow rate fluctuation range the greater the deviation from the target value, or the flow rate may be divided into several stages and a value corresponding to each stage may be used. The required flow rate is determined by dividing this required flow rate by the number of operating reverse osmosis membrane separation apparatuses 205-1 to 205-4 among the reverse osmosis membrane separation apparatuses 205-1 to 205-4. Based on the calculated required flow rate, the control unit 240 controls the pumps 204-1 to 204-4 so that the flow rates indicated by the flow rate values ​​of the flow meters 206-1 to 206-4 acquired by the acquisition unit 230 each reach the required flow rate. Specifically, control unit 240 controls the flow rate of the water to be treated supplied from pumps 204-1 to 204-4 by controlling the frequency of the inverters provided in pumps 204-1 to 204-4 so that the flow rates indicated by the flow rate values ​​of flow meters 206-1 to 206-4 acquired by acquisition unit 230 are equal to the required flow rates. Note that the destinations of the water to be treated in this case are use points downstream of electrodeionized water production apparatuses 213-1 to 213-4.The destinations of the supply may be the electrodeionized water production apparatuses 213-1 to 213-4 themselves, water treatment devices (e.g., ultraviolet oxidation devices, ion exchange resin filling devices, membrane degassing devices, etc.) installed in primary pure water production systems other than the primary pure water production system 20, tanks for storing water to be treated, or devices or systems that use the water treated by the reverse osmosis membrane separation devices 205-1 to 205-4. Furthermore, the number of destination electrodeionized water production apparatuses and use points, etc., is not limited. This also applies to the following explanation.

[0030] Furthermore, when the calculated required flow rate is below a predetermined first threshold (hereinafter referred to as threshold A), the control unit 240 stops operation of at least one of the reverse osmosis membrane separation units 205-1 to 205-4. For example, when the calculated required flow rate is below threshold A, the control unit 240 may control the on-off valves 203 and 208 to a closed state to isolate the reverse osmosis membrane separation unit 205-1 and stop operation of the reverse osmosis membrane separation unit 205-1. At this time, the control unit 240 may control the on-off valve 207 to switch the treated water flowing out from the reverse osmosis membrane separation unit 205-1 to a flow path that returns the treated water to the RO raw water tank 200 via a circulation path to the RO raw water tank 200.

[0031] After stopping the operation of at least one of the reverse osmosis membrane separation apparatuses 205-1 to 205-4, if the calculated required flow rate becomes equal to or greater than a second threshold value set in advance (hereinafter referred to as threshold value B), the control unit 240 resumes the operation of the reverse osmosis membrane separation apparatus that has been stopped. This threshold value B is greater than threshold value A. For example, the control unit 240 may control the on-off valves 203 and 208 to a closed state to stop the operation of the reverse osmosis membrane separation apparatus 205-1, and then control the on-off valves 203 and 208 to an open state to resume the operation of the reverse osmosis membrane separation apparatus 205-1 if the calculated required flow rate becomes equal to or greater than threshold value B.

[0032] The processing of the control device 220 will be described below using a specific example. FIGS. 4 and 5 are diagrams for explaining an example of the processing of the control device 220 shown in FIG. 2 in chronological order. In the following description, the threshold value A is set to 2.0 (m 3 / h), and the threshold B is 3.5 (m 3 / h). From the viewpoint of stabilizing water quality, thresholds A and B are set to 60 to 140%, preferably 75 to 125%, and more preferably 80 to 120% of a preset amount of treated water. Narrowing the range of the thresholds allows for stable water quality. The branch path of reverse osmosis membrane separation device 205-1 is designated as system A, the branch path of reverse osmosis membrane separation device 205-2 is designated as system B, the branch path of reverse osmosis membrane separation device 205-3 is designated as system C, and the branch path of reverse osmosis membrane separation device 205-4 is designated as system D. In the initial state, all of the reverse osmosis membrane separation devices 205-1 to 205-4 are in operation. Each of the reverse osmosis membrane separation devices 205-1 to 205-4 is configured with three 8-inch RO membrane elements. The normal permeate rate per 8-inch RO membrane element is 1.11 m 3 / h (3.33m for 3 pieces) 3 / h) is taken as an example. In addition, the recovery rate of each of the reverse osmosis membrane separation devices 205-1 to 205-4 (flow rate measured by each of the flow meters 206-1 to 206-4 / amount of water supplied to each of the reverse osmosis membrane separation devices 205-1 to 205-4) is 80%, and the recovery rate of each of the electrodeionized water production devices 213-1 to 213-4 (flow rate measured by each of the flow meters 214-1 to 214-4 / amount of water supplied to each of the electrodeionized water production devices 213-1 to 213-4) is 90%.

[0033] First, as shown in Figure 4(a), the required flow rate of desalinated water is 12 (m 3 / h), the required flow rate of desalinated water from EDI is calculated by dividing the required flow rate by the number of systems in operation. 12÷4=3.0(m 3 / h) The required flow rate at this time may be a flow rate value acquired by the acquisition unit 230 from the flow meter 215, or may be a value calculated by the control unit 240 based on the water level value acquired by the acquisition unit 230 from the water level meter 211 and the recovery rate of each of the electrodeionized water production apparatuses 213-1 to 213-4. The control unit 240 can calculate the amount of treated water to be supplied to the supply destination by using the cross-sectional area of ​​the EDI raw water tank 210 and the water level value acquired by the acquisition unit 230 from the water level meter 211. The control unit 240 calculates the required flow rate of permeated water from the RO for each system based on the calculated required flow rate of desalinated water from the EDI for each system and the recovery rate of each of the electrodeionized water production apparatuses 213-1 to 213-4. Specifically, the required flow rate of permeated water from the RO for each system is 3.0÷90(%)=3.33(m 3 / h) The control unit 240 determines that the flow rate values ​​acquired by the acquisition unit 230 from the flow meters 206-1 to 206-4 are 3.33 (m 3 / h). The control unit 240 compares the calculated required flow rate with threshold A. At this time, the calculated required flow rate does not fall below threshold A.

[0034] Next, as shown in Figure 4(b), the required flow rate of desalinated water is 10 (m 3 / h), the required flow rate of desalinated water from EDI is calculated by dividing the required flow rate by the number of systems in operation. 10÷4=2.5(m 3 / h) The required flow rate at this time may be a flow rate value acquired by the acquisition unit 230 from the flow meter 215, or may be a value calculated by the control unit 240 based on the water level value acquired by the acquisition unit 230 from the water level meter 211 and the recovery rate of each of the electrodeionized water production apparatuses 213-1 to 213-4. The control unit 240 calculates the required flow rate of permeated water from the RO for each system based on the calculated required flow rate of desalted water from the EDI for each system and the recovery rate of each of the electrodeionized water production apparatuses 213-1 to 213-4. Specifically, the required flow rate of permeated water from the RO for each system is 2.5÷90(%)=2.78(m 3 / h) The control unit 240 determines that the flow rate values ​​acquired by the acquisition unit 230 from the flow meters 206-1 to 206-4 are 2.78 (m 3 / h). The control unit 240 compares the calculated required flow rate with threshold A. At this time, the calculated required flow rate does not fall below threshold A.

[0035] Next, as shown in Figure 4(c), the required flow rate of desalinated water is 7 (m 3 / h), the required flow rate of desalinated water from EDI is calculated by dividing the required flow rate by the number of systems in operation. 7÷4=1.75(m 3 / h) The required flow rate at this time may be a flow rate value acquired by the acquisition unit 230 from the flow meter 215, or may be a value calculated by the control unit 240 based on the water level value acquired by the acquisition unit 230 from the water level meter 211 and the recovery rate of each of the electrodeionized water production apparatuses 213-1 to 213-4. The control unit 240 calculates the required flow rate of permeated water from the RO for each system based on the calculated required flow rate of desalted water from the EDI for each system and the recovery rate of each of the electrodeionized water production apparatuses 213-1 to 213-4. Specifically, the required flow rate of permeated water from the RO for each system is 1.75÷90(%)=1.94(m 3 / h) The control unit 240 determines that the flow rate values ​​acquired by the acquisition unit 230 from the flow meters 206-1 to 206-4 are 1.94 (m 3 / h). The control unit 240 compares the calculated required flow rate with threshold A. Because the calculated required flow rate is below threshold A, the control unit 240 decides to isolate one system (system A of the reverse osmosis membrane separation device 205-1 in this case) and stop its operation. As shown in FIG. 4(d), before isolating system A (stopping the operation of the reverse osmosis membrane separation device 205-1), the control unit 240 reduces the flow rate of desalinated water by 7 (m 3 / h), the flow rate values ​​acquired by the acquisition unit 230 from the flow meters 206-2 to 206-4 are 7÷90%÷3=2.59(m 3 / h) Here, the control unit 240 disconnects the system A, and at the same time, the acquisition unit 230 acquires the flow rate values ​​from the flow meters 206-2 to 206-4, respectively, of 1.94 (m 3 / h) to 2.59(m 3 / h), but to be on the safe side, before isolating system A, the flow rate values ​​obtained from the flow meters 206-2 to 206-4 are set to 2.59 (m 3 It is preferable to control the frequencies of the pumps 204-2 to 204-4 so that the frequency of the pumps 204-2 to 204-4 is equal to or greater than the predetermined value ( / h).

[0036] Next, as shown in FIG. 4( e), the control unit 240 isolates system A. At this time, the control unit 240 controls the on-off valves 203 and 208 to be closed, preventing the untreated water from flowing into the reverse osmosis membrane separation device 205-1. At this time, the control unit 240 may control the on-off valve 207 to switch the treated water flowing out of the reverse osmosis membrane separation device 205-1 to a flow path that returns the treated water to the RO raw water tank 200 via a circulation path to the RO raw water tank 200. The control unit 240 may also stop the operation of the reverse osmosis membrane separation device 205-1. While the reverse osmosis membrane separation device 205-1 is isolated in this state, the control unit 240 may pass the untreated water through the reverse osmosis membrane separation device 205-1 for any period of time and at any frequency. By passing water through the isolated reverse osmosis membrane separation device 205-1, water retention during shutdown can be suppressed, and the reverse osmosis membrane separation device 205-1 can be restarted more quickly. At this time, it is preferable to circulate the water to be treated discharged from the reverse osmosis membrane separation device 205-1 to the RO raw water tank 200. The inlet pressure of the reverse osmosis membrane separation device 205-1 during circulation is 0.5 MPa or less, preferably 0.3 MPa or less. Note that the higher the recovery rate in the reverse osmosis membrane separation device 205-1, the higher the quality and pressure of the treated water circulated from the reverse osmosis membrane separation device 205-1.

[0037] After that, as shown in Figure 5(a), the required flow rate of desalinated water is 12 (m 3 / h), the required flow rate of desalinated water from EDI is calculated by dividing the required flow rate by the number of systems in operation. 12÷4=3(m 3 / h) The required flow rate at this time may be a flow rate value acquired by the acquisition unit 230 from the flow meter 215, or may be a value calculated by the control unit 240 based on the water level value acquired by the acquisition unit 230 from the water level meter 211 and the recovery rate of each of the electrodeionized water production apparatuses 213-1 to 213-4. The control unit 240 calculates the required flow rate of permeated water from the RO for each system based on the calculated required flow rate of desalted water from the EDI for each system and the recovery rate of each of the electrodeionized water production apparatuses 213-1 to 213-4. Specifically, the required flow rate of permeated water from the RO for each system is 3×4÷90(%)÷3=4.44(m 3 / h) The control unit 240 determines that the flow rate values ​​acquired by the acquisition unit 230 from the flow meters 206-2 to 206-4 are 4.44 (m 3 / h). The control unit 240 compares the calculated required flow rate with threshold B. Because the calculated required flow rate is equal to or greater than threshold B, the control unit 240 determines to resume operation of the system that was isolated and stopped (system A of the reverse osmosis membrane separation device 205-1).

[0038] As shown in FIG. 5(b), the control unit 240 controls the on-off valves 203 and 208 of the system that has been isolated and stopped (system A of the reverse osmosis membrane separation apparatus 205-1) to an open state, thereby restarting the operation of the reverse osmosis membrane separation apparatus 205-1. If the open / close state of the on-off valve 207 is such that the treated water flowing out from the reverse osmosis membrane separation apparatus 205-1 serves as a flow path that returns to the RO raw water tank 200 via a circulation path to the RO raw water tank 200, the control unit 240 controls the on-off valve 207 so that the treated water flowing out from the reverse osmosis membrane separation apparatus 205-1 flows into the path to the EDI raw water tank 210. At this time, the control unit 240 controls the flow rate value acquired by the acquisition unit 230 from the flow meter 206-1 to be 4.44 (m 3 / h). The control unit 240 controls the frequency of the pump 204-1 so that the flow rate value acquired by the acquisition unit 230 from the flow meter 206-1 is 4.44 (m 3 / h). After the control unit 240 controls the on-off valves 203 and 208 of the system that has been isolated and stopped to be open (and also controls the on-off state of the on-off valve 207 if necessary), the control unit 240 may perform a raw water return operation by passing water through a blowing or circulation path for a predetermined period of time.

[0039] After the four systems A to D have started operation, as shown in FIG. 5(c), the control unit 240 receives the flow rate values ​​acquired by the acquisition unit 230 from the flow meters 206-1 to 206-4. 12÷90(%)÷4=3.33(m 3 / h) The frequencies of the pumps 204-1 to 204-4 are controlled so as to satisfy the following equation.

[0040] The threshold value A described above is a threshold value for preventing the quality of treated water from deteriorating due to a low flow rate to the reverse osmosis membrane separation devices 205-1 to 205-4, and the threshold value B is a threshold value for preventing the reverse osmosis membrane separation devices 205-1 to 205-4 from being damaged due to a high flow rate to the reverse osmosis membrane separation devices 205-1 to 205-4.

[0041] The following describes an operation method of the control device 220 shown in Fig. 2. Fig. 6 is a flowchart for explaining an example of processing when the amount of treated water supplied to the supply destination decreases, among the operation methods of the control device 220 shown in Fig. 2. The specific processing in this flow is the processing described using Fig. 4.

[0042] First, after starting to pass water through the reverse osmosis membrane separation devices 205-1 to 205-4, the acquisition unit 230 acquires the water level value of the treated water stored in the EDI raw water tank 210 from the water level meter 211 (step S1). The control unit 240 calculates the amount of change in the amount of treated water supplied to the supply destination based on the water level value acquired by the acquisition unit 230 (step S2). The control unit 240 determines whether the amount of treated water supplied to the supply destination has decreased (step S3). If the amount of treated water supplied to the supply destination has decreased, the control unit 240 calculates the required flow rate from the calculated amount of change and calculates the required flow rate described above. The control unit 240 reduces the frequency of each of the pumps 204-1 to 204-4 so that the flow rate values ​​acquired by the acquisition unit 230 from the flow meters 206-1 to 206-4 respectively become values ​​indicating the calculated required flow rates (step S4). The control unit 240 determines whether the calculated required flow rate is below threshold A (step S5). If the calculated required flow rate is below threshold A, the control unit 240 increases the frequency of each of the pumps 204-1 to 204-4 (step S6). At this time, the control unit 240 does not need to increase the frequency of each of all of the pumps 204-1 to 204-4; it is sufficient to increase the frequency of the pumps other than the pumps in the series to be stopped. Next, the control unit 240 isolates some of the reverse osmosis membrane separation devices to stop their operation (step S7). Here, the control unit 240 controls the on-off valves 203 and 208 to a closed state to isolate the reverse osmosis membrane separation device 205-1 and stop the operation of the reverse osmosis membrane separation device 205-1. At this time, the control unit 240 may control the on-off valve 207 to switch the flow path to return the treated water flowing out from the reverse osmosis membrane separation device 205-1 to the RO raw water tank 200 via a circulation path to the RO raw water tank 200.

[0043] In step S3, if the amount of treated water supplied to the destination has not changed, the process of step S1 is performed. In addition, in step S3, if the amount of treated water supplied to the destination has increased, the process described below (the process described with reference to FIG. 7) is performed.

[0044] Fig. 7 is a flowchart illustrating an example of the processing performed when the amount of treated water supplied to the supply destination increases, among the operating methods of the control device 220 shown in Fig. 2. The specific processing in this flow is the processing described using Fig. 5. The processing described below is the processing performed from a state in which the operation of the reverse osmosis membrane separation device 205-1 has stopped.

[0045] First, the acquisition unit 230 acquires the water level value of the treated water stored in the EDI raw water tank 210 from the water level meter 211 (step S11). The control unit 240 calculates the amount of change in the amount of treated water supplied to the supply destination based on the water level value acquired by the acquisition unit 230 (step S12). The control unit 240 determines whether the amount of treated water supplied to the supply destination has increased (step S13). If the amount of treated water supplied to the supply destination has increased, the control unit 240 calculates the required flow rate from the calculated amount of change, and calculates the required flow rate described above. The control unit 240 increases the frequency of each of the pumps 204-2 to 204-4 so that the flow rate values ​​acquired from the flow meters 206-2 to 206-4 each become values ​​indicating the calculated required flow rate (step S14). The control unit 240 determines whether the calculated required flow rate is equal to or greater than threshold B (step S15). If the calculated required flow rate is equal to or greater than threshold B, the control unit 240 resumes operation of the reverse osmosis membrane separation apparatus 205-1, which had been stopped (step S16). Next, the control unit 240 lowers the frequency of each of the pumps 204-2 to 204-4 so that the flow rate values ​​acquired by the acquisition unit 230 from the flow meters 206-1 to 206-4 respectively become the required flow rates corresponding to the number of reverse osmosis membrane separation apparatuses 205-1 to 205-4 in operation (step S17).

[0046] In step S13, if the amount of treated water supplied to the destination has not changed, the process of step S11 is performed. Also, in step S13, if the amount of treated water supplied to the destination has decreased, the process described above (the process described with reference to FIG. 6) is performed.

[0047] In this embodiment, the flow rate of each of multiple water treatment devices arranged in parallel is controlled according to the amount of treated water used at the destination. If the required flow rate of each water treatment device falls below threshold A, some of the water treatment devices are stopped. Furthermore, if the required flow rate of each water treatment device exceeds threshold B after stopping some of the water treatment devices, the stopped water treatment devices are restarted. This allows for fine adjustment of the treated water supply rate without degrading the quality of the treated water. Multiple thresholds may be set, and the number of water treatment devices to be stopped may be increased as the required flow rate decreases. For example, if the required flow rate of each water treatment device falls below threshold A, one water treatment device may be stopped. If the required flow rate of each water treatment device falls below threshold A1, which is smaller than threshold A, another water treatment device may be stopped. If the required flow rate of each water treatment device falls below threshold A2, which is smaller than threshold A1, another water treatment device may be stopped. In this case, three thresholds for restarting operation may also be provided, and operation may be restarted sequentially based on the results of comparing the required flow rate with each of the three thresholds as the required flow rate increases. (Second embodiment)

[0048] Figure 8 is a diagram showing a second embodiment of a primary pure water production system 21 that is applied to the water treatment system shown in Figure 1. The primary pure water production system 21 shown in Figure 8 is provided in place of the primary pure water production system 20 of the water treatment system shown in Figure 1. As shown in Figure 8, the primary pure water production system 21 includes an RO raw water tank 200, pumps 201, 204-1 to 204-4, and 212, a filter 202, on-off valves 203, 207 to 209, and 217, reverse osmosis membrane separation (RO) devices 205-1 to 205-4, flow meters 206-1 to 206-4, 214-1 to 214-4, and 215, an EDI raw water tank 210, a water level gauge 211, electrodeionized water production devices 213-1 to 213-4, a demineralized water tank 216, and a control device 221. 8 shows only the main components related to this embodiment of the primary pure water production system 21 that is applied to the water treatment system shown in FIG. 1. For example, a water treatment device such as an ultraviolet oxidation device that irradiates the water to be treated with ultraviolet light to decompose organic matter contained in the water may be provided upstream of the electrodeionized water production devices 213-1 to 213-4. Also, a water treatment device such as a membrane degassing device that removes dissolved oxygen may be provided downstream of the electrodeionized water production devices 213-1 to 213-4.

[0049] The RO raw water tank 200, pumps 201, 204-1 to 204-4, 212, filter 202, on-off valves 203, 207 to 209, 217, reverse osmosis membrane separation (RO) devices 205-1 to 205-4, flow meters 206-1 to 206-4, 214-1 to 214-4, 215, EDI raw water tank 210, water level gauge 211, electrical deionized water production devices 213-1 to 213-4 and desalinated water tank 216 are each the same as those in the first embodiment.

[0050] The control device 221 controls the opening and closing of the pumps 204-1 to 204-4 and the on-off valves 203 and 208 or the operation of the reverse osmosis membrane separation device 205-1 based on the flow rate values ​​notified from the flow meters 206-1 to 206-4 and the water level value notified from the water level meter 211. FIG. 9 is a diagram showing an example of components included in the control device 221 shown in FIG. 8. As shown in FIG. 9, the control device 221 shown in FIG. 8 has an acquisition unit 230 and a control unit 241. Note that FIG. 9 shows main elements in this embodiment among the components included in the control device 221 shown in FIG. 8. The acquisition unit 230 is the same as that in the first embodiment.

[0051] The control unit 241 calculates the required flow rate of treated water to be supplied from the reverse osmosis membrane separation apparatuses 205-1 to 205-4 to the supply destination based on the water level value acquired by the acquisition unit 230 from the water level meter 211. The specific calculation method may be the same as that in the first embodiment. The required flow rate is obtained by dividing this required flow rate by the number of reverse osmosis membrane separation apparatuses 205-1 to 205-4 that are operating among the reverse osmosis membrane separation apparatuses 205-1 to 205-4. The control unit 241 controls the pumps 204-1 to 204-4 based on the calculated required flow rate so that the flow rates indicated by the flow rate values ​​of the flow meters 206-1 to 206-4 acquired by the acquisition unit 230 each become the required flow rate. The specific control method may be the same as that in the first embodiment.

[0052] Furthermore, when the calculated required flow rate is below a preset threshold A, the control unit 241 stops operation of at least one of the reverse osmosis membrane separation units 205-1 to 205-4. For example, when the calculated required flow rate is below the threshold A, the control unit 241 may control the on-off valves 203 and 208 to a closed state to isolate the reverse osmosis membrane separation unit 205-1 and stop operation of the reverse osmosis membrane separation unit 205-1. At this time, the control unit 241 may control the on-off valve 207 to switch the treated water flowing out of the reverse osmosis membrane separation unit 205-1 to a flow path that returns the treated water to the RO raw water tank 200 via a circulation path to the RO raw water tank 200.

[0053] After stopping the operation of at least one of the reverse osmosis membrane separation apparatuses 205-1 to 205-4, the control unit 241 restarts the operation of the stopped reverse osmosis membrane separation apparatus if the calculated required flow rate is equal to or greater than threshold value A. For example, the control unit 241 may control the on-off valves 203, 208 to a closed state to isolate the reverse osmosis membrane separation apparatus 205-1 and stop the operation of the reverse osmosis membrane separation apparatus 205-1, and then control the on-off valves 203, 208 to an open state to restart the operation of the reverse osmosis membrane separation apparatus 205-1 if the calculated required flow rate is equal to or greater than threshold value A even after restarting the operation of the stopped reverse osmosis membrane separation apparatus. If the open / close state of the on-off valve 207 is such that the treated water flowing out from the reverse osmosis membrane separation device 205-1 is returned to the RO raw water tank 200 via a circulation path to the RO raw water tank 200, the control unit 241 controls the on-off valve 207 so that the treated water flowing out from the reverse osmosis membrane separation device 205-1 flows into the path to the EDI raw water tank 210.

[0054] The processing of the control device 221 will be described below using a specific example. The processing of the control device 221 when the calculated required flow rate falls below the preset threshold A may be the same as the processing of the control device 220 in the first embodiment. FIG. 10 is a diagram for explaining an example of the processing of the control device 221 shown in FIG. 8 in chronological order. In the following description, the threshold A is set to 2.0 (m 3 / h). The branch path of the reverse osmosis membrane separation device 205-1 is designated as system A, the branch path of the reverse osmosis membrane separation device 205-2 is designated as system B, the branch path of the reverse osmosis membrane separation device 205-3 is designated as system C, and the branch path of the reverse osmosis membrane separation device 205-4 is designated as system D. In the initial state, the operation of the reverse osmosis membrane separation device 205-1 is stopped, and the reverse osmosis membrane separation devices 205-2 to 205-4 are in operation.

[0055] As shown in FIG. 10(a), when the operation of the reverse osmosis membrane separation device 205-1 is stopped, the flow rate of desalinated water, which is the required flow rate, is 10 (m 3 / h), the required flow rate of desalinated water from EDI is calculated by dividing the required flow rate by the number of systems in operation. 10÷4=2.5(m 3 / h) The required flow rate at this time may be a flow rate value acquired by the acquisition unit 230 from the flow meter 215, or may be a value calculated by the control unit 241 based on the water level value acquired by the acquisition unit 230 from the water level meter 211 and the recovery rate of each of the electrodeionized water production apparatuses 213-1 to 213-4. The control unit 241 calculates the required flow rate of permeated water from the RO for each system based on the calculated required flow rate of desalted water from the EDI for each system and the recovery rate of each of the electrodeionized water production apparatuses 213-1 to 213-4. Specifically, the required flow rate of permeated water from the RO for each system is 2.5×4÷90(%)÷3=3.7(m 3 / h) The control unit 241 determines that the flow rate values ​​acquired by the acquisition unit 230 from the flow meters 206-2 to 206-4 are 3.7 (m 3 The frequencies of the pumps 204-2 to 204-4 are controlled so that the frequency of the pumps 204-2 to 204-4 is equal to or greater than 1 / h.

[0056] In addition, the control unit 241 3 When treated water (permeate) is supplied from the four reverse osmosis membrane separation devices 205-1 to 205-4 at a flow rate of (1 / h), the required flow rate for each of the reverse osmosis membrane separation devices 205-1 to 205-4 is calculated. The required flow rate for each of the reverse osmosis membrane separation devices 205-1 to 205-4 is calculated as follows: 2.5×4÷90(%)÷4=2.78(m 3 / h) The control unit 241 compares the calculated required flow rate with threshold value A. The calculated required flow rate is equal to or greater than threshold value A. Therefore, the control unit 241 decides to resume operation of the system that was isolated and stopped (system A of the reverse osmosis membrane separation device 205-1).

[0057] As shown in FIG. 10(b), the control unit 241 controls the on-off valves 203 and 208 of the system (system A of the reverse osmosis membrane separation apparatus 205-1) that has been isolated and stopped to an open state (and also controls the on-off state of the on-off valve 207 if necessary), and resumes operation of the reverse osmosis membrane separation apparatus 205-1. At this time, the control unit 241 detects that the flow rate value acquired by the acquisition unit 230 from the flow meter 206-1 is 3.7 (m 3 / h). The control unit 241 controls the frequency of the pump 204-1 so that the flow rate value acquired by the acquisition unit 230 from the flow meter 206-1 is 3.7 (m 3 The frequency of the pump 204-1 may be controlled to a value other than 1 / h.

[0058] After the four systems A to D have started operation, as shown in FIG. 10(c), the control unit 241 receives the flow rate values ​​acquired by the acquisition unit 230 from the flow meters 206-1 to 206-4. 2.5×4÷90(%)÷4=2.78(m 3 / h) The frequencies of the pumps 204-1 to 204-4 are controlled so as to satisfy the following equation.

[0059] An operation method of the control device 221 shown in Fig. 8 will be described below. Of the operation methods of the control device 221 shown in Fig. 8, the processing when the amount of treated water supplied to the supply destination decreases may be the same as that in the first embodiment. Fig. 11 is a flowchart for explaining an example of the processing when the amount of treated water supplied to the supply destination increases, among the operation methods of the control device 221 shown in Fig. 8. The specific processing in this flow is the processing described using Fig. 10. The processing described below is processing starting from a state in which the operation of the reverse osmosis membrane separation device 205-1 is stopped.

[0060] First, the acquisition unit 230 acquires the water level value of the treated water stored in the EDI raw water tank 210 from the water level meter 211 (step S21). The control unit 241 calculates the amount of change in the amount of treated water supplied to the supply destination based on the water level value acquired by the acquisition unit 230 (step S22). The control unit 241 determines whether the amount of treated water supplied to the supply destination has increased (step S23). If the amount of treated water supplied to the supply destination has increased, the control unit 241 calculates the required flow rate from the calculated amount of change, and calculates the required flow rate described above. The control unit 241 increases the frequency of each of the pumps 204-2 to 204-4 so that the flow rate values ​​acquired from the flow meters 206-2 to 206-4 each become the value indicating the calculated required flow rate (step S24).

[0061] The control unit 241 also calculates the required flow rates for each of the reverse osmosis membrane separation devices 205-1 to 205-4 when the operation of the reverse osmosis membrane separation device 205-1, which has been stopped, is resumed and treated water is supplied at a required flow rate from the four reverse osmosis membrane separation devices 205-1 to 205-4. The control unit 241 determines whether the calculated required flow rates are equal to or greater than threshold A (step S25). If the calculated required flow rates are equal to or greater than threshold A, the control unit 241 resumes operation of the reverse osmosis membrane separation device 205-1, whose operation has been stopped (step S26). Next, the control unit 241 lowers the frequency of each of the pumps 204-2 to 204-4 so that the flow rate values ​​acquired by the acquisition unit 230 from the flow meters 206-1 to 206-4, respectively, become the required flow rates corresponding to the number of reverse osmosis membrane separation devices 205-1 to 205-4 in operation (step S27).

[0062] In step S23, if the amount of treated water supplied to the destination has not changed, the process of step S21 is performed. Also, in step S23, if the amount of treated water supplied to the destination has decreased, the process described above is performed.

[0063] In this manner, in this embodiment, the flow rate of each of multiple water treatment devices arranged in parallel is controlled according to the amount of treated water used at the destination. In this case, if the required flow rate of each water treatment device after the control of the treated water falls below threshold A, operation of some of the multiple water treatment devices is stopped. Furthermore, if the required flow rate increases after stopping operation of some of the water treatment devices, and the required flow rate of each water treatment device when the stopped water treatment devices are restarted exceeds threshold A, operation of the stopped water treatment devices is restarted. This allows for fine adjustment of the supply rate of treated water without degrading the quality of the treated water. Furthermore, since only one threshold is used, control is simplified.

[0064] Although the above description has been given by allocating each function (process) to each component, this allocation is not limited to the above. Furthermore, the configuration of the components is also not limited to the above-described form, which is merely an example.

[0065] The processes performed by the control devices 220 and 221 described above may be performed by logic circuits manufactured for each purpose. Alternatively, a computer program (hereinafter referred to as a program) describing the process procedures may be recorded on a recording medium readable by each of the control devices 220 and 221, and the program recorded on the recording medium may be read and executed by each of the control devices 220 and 221. Examples of recording media readable by the control devices 220 and 221 include removable recording media such as floppy disks, magneto-optical disks, DVDs (Digital Versatile Discs), CDs (Compact Discs), Blu-ray (registered trademark) Discs, USB (Universal Serial Bus) memories, and SD cards, as well as memories such as ROMs (Read Only Memory), RAMs (Random Access Memory), and HDDs (Hard Disc Drives) built into each of the control devices 220 and 221. The program recorded on this recording medium is read by a CPU (not shown) provided in each of the control devices 220 and 221, and the same processing as described above is performed under the control of the CPU. Here, the CPU operates as a computer that executes the program read from the recording medium on which the program is recorded. [Explanation of symbols]

[0066] 10 Pretreatment System 20,21 Primary pure water production system 30 Subsystems 200 RO raw water tank 201, 204-1 to 204-4, 212 Pumps 202 filters 203, 207~209, 217 Opening and closing valves 205-1~205-4 Reverse osmosis membrane separation equipment 206-1~206-4,214-1~214-4,215 Flowmeter 210 EDI raw water tank 211 Water level gauge 213-1~213-4 Electrodeionized water production equipment 216 Desalination Tank 220,221 Control device 230 Acquisition Department 240,241 Control unit

Claims

1. a plurality of water treatment devices arranged in parallel to each other and performing predetermined treatment on the water to be treated; a plurality of pumps that supply the water to be treated to each of the plurality of water treatment devices; a control device that controls the operation of the plurality of pumps and the plurality of water treatment devices so that the flow rate of treated water flowing out from each of the plurality of water treatment devices is a required flow rate according to the amount of treated water supplied from the plurality of water treatment devices to a supply destination, The control device stops operation of at least one of the plurality of water treatment devices when the required flow rate falls below a first threshold, and after stopping operation of at least one of the plurality of water treatment devices, resumes operation of at least one of the water treatment devices whose operation has been stopped when the required flow rate becomes equal to or greater than a second threshold that is greater than the first threshold.

2. The water treatment facility according to claim 1, a water tank for storing treated water to be supplied from each of the plurality of water treatment devices to the supply destination; a water level meter for measuring the water level of the treated water stored in the water tank, The control device is a water treatment facility that calculates the required flow rate based on the water level measured by the water level meter.

3. The water treatment facility according to claim 1 or 2, The control device stops operation of at least one of the plurality of water treatment devices, and then, if the required flow rate remains above the first threshold even after restarting operation of the water treatment device, restarts operation of at least one of the water treatment devices whose operation has been stopped.

4. The water treatment facility according to claim 1 or 2, The control device increases the supply amount from the plurality of pumps to water treatment devices other than the water treatment device whose operation is to be stopped before stopping the operation of at least one of the plurality of water treatment devices.

5. The water treatment facility according to claim 1 or 2, The water treatment facility is a reverse osmosis membrane separation device or an electrodeionization water production device that operates at a constant recovery rate.

6. The water treatment device according to claim 5, The control device starts supplying water to the reverse osmosis membrane separation device or the electrodeionized water production device, and if the required flow rate is below a first threshold, stops operation of at least one of the water treatment devices, which are the reverse osmosis membrane separation device or the electrodeionized water production device, and after stopping operation of the at least one of the reverse osmosis membrane separation device or the electrodeionized water production device, resumes operation of the stopped reverse osmosis membrane separation device or the electrodeionized water production device if the required flow rate becomes equal to or greater than a second threshold that is greater than the first threshold.

7. The water treatment facility according to claim 1 or 2, a water tank provided upstream of the plurality of pumps; an on-off valve provided in a path returning treated water flowing out of each of the plurality of water treatment devices to the water tank; The control device controls the opening and closing or the opening degree of the on-off valve to return at least a portion of the treated water flowing out from each of the plurality of water treatment devices to the water tank.

8. an acquisition unit that acquires a plurality of flow rate values ​​that indicate the flow rate of treated water flowing out from each of a plurality of water treatment devices that are arranged in parallel with each other; a control unit that controls a plurality of pumps that supply the water to be treated to each of the plurality of water treatment devices and an operation of the plurality of water treatment devices so that the flow rates indicated by the plurality of flow rate values ​​acquired by the acquisition unit are required flow rates according to the amount of treated water supplied from the plurality of water treatment devices to a supply destination; The control unit is a control device that stops operation of at least one of the plurality of water treatment devices when the required flow rate falls below a first threshold, and after stopping operation of at least one of the plurality of water treatment devices, resumes operation of at least one of the water treatment devices that has been stopped when the required flow rate becomes equal to or greater than a second threshold that is greater than the first threshold.

9. A process of acquiring a plurality of flow rate values ​​indicating the flow rate of treated water flowing out from each of a plurality of water treatment devices arranged in parallel with each other; a process of controlling the operation of a plurality of pumps that supply the water to be treated to each of the plurality of water treatment devices and the plurality of water treatment devices so that the flow rates indicated by the plurality of flow rate values ​​become the required flow rates corresponding to the amounts of treated water supplied from the plurality of water treatment devices to the supply destinations; If the required flow rate is below a first threshold, stopping operation of at least one of the plurality of water treatment devices; an operating method for stopping operation of at least one of the plurality of water treatment devices, and then, if the required flow rate becomes equal to or greater than a second threshold value that is greater than the first threshold value, restarting operation of at least one of the water treatment devices whose operation has been stopped.

10. On the computer, acquiring a plurality of flow rate values ​​indicating the flow rate of treated water flowing out of each of a plurality of water treatment devices arranged in parallel with one another; a step of controlling the operation of a plurality of pumps that supply the water to be treated to each of the plurality of water treatment devices and the plurality of water treatment devices so that the flow rates indicated by the plurality of flow rate values ​​become the required flow rates corresponding to the amounts of treated water supplied from the plurality of water treatment devices to the supply destinations; If the required flow rate is below a first threshold, stopping operation of at least one of the plurality of water treatment devices; and a program for executing a procedure for restarting operation of at least one of the plurality of water treatment devices whose operation has been stopped if the required flow rate becomes equal to or greater than a second threshold value that is greater than the first threshold value after the operation of at least one of the water treatment devices has been stopped.

Images