Water Treatment Systems

Abstract

To estimate an operating status of a customer facility and automatically starting and stopping a water purifier to reduce a running cost.SOLUTION: A water treatment system includes: a primary water purifier 12; a sub-tank 30; a water level gauge 34 that measures a water level of the sub-tank 30; a primary pure water line 20; a circulation line 22 that circulates primary pure water to an upstream side of the primary water purifier 12; a water level adjustment valve; and a control unit 50 that adjusts an opening degree of the water level adjustment valve so that the water level of the sub-tank 30 is constant. The control unit 50 stops the primary water purifier 12 when a state where the opening degree of the water level adjustment valve becomes a predetermined value or less is continued for a predetermined period of time, or adjusts the opening degree of the water level adjustment valve so that at least a part of the primary pure water is refluxed in the circulation line 22.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a water treatment system. [Background technology]

[0002] Raw water is treated using a water purification system equipped with a reverse osmosis membrane device, an electric deionization device, etc. to produce pure water, which is then stored in a sub-tank (pure water tank) and supplied to points of use.

[0003] The pure water tank is controlled to maintain a constant water level within the tank, and for example, Patent Document 1 describes operating a pure water production system to replenish the pure water tank with pure water when the amount of water stored in the pure water tank falls below a certain level. Patent Document 2 also describes maintaining a constant water level using a water level meter or the like to reduce nitrogen consumption in the gas phase of the pure water tank.

[0004] The deionized water system, which is used to replenish deionized water to the sub-tank, operates in a constant circulation mode, adjusting the water flow rate and circulation volume using the three-way water level adjustment valve at the sub-tank inlet. The deionized water in the sub-tank is constantly used when the factory is in operation, but is not used when the factory is closed. However, because the deionized water system operates in a constant circulation mode even when the sub-tank does not need to be replenished, unnecessary electricity running costs are incurred.

[0005] When the factory is closed, the operator manually operates the master switch to "stop" to shut down the pure water system. However, manual operation can cause problems with the pure water supply if the master switch is forgotten to be operated while the factory is in operation. For this reason, there is a need for a system that can automatically stop and restart the pure water system.

[0006] However, because the sub-tank's water level is controlled to a constant level using a water level gauge and a three-way water level control valve, it was not possible to measure the amount of pure water used from fluctuations in the water level, and the factory's operating status could not be determined. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 5785000 [Patent Document 2] Patent No. 4978592 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a water treatment system that estimates the operating status of a customer's facility and automatically starts and stops a pure water system, thereby reducing running costs. [Means for solving the problem]

[0009] The water treatment system according to the present invention comprises a primary pure water apparatus that treats water to be treated to produce primary pure water, a sub-tank that stores the primary pure water, a water level gauge that measures the water level in the sub-tank, a primary pure water line connecting the primary pure water apparatus and the sub-tank, a circulation line that returns the primary pure water from the primary pure water line to the upstream side of the primary pure water apparatus, a water level control valve provided on the primary pure water line, and a control unit that acquires the measurement results of the water level gauge and adjusts the opening of the water level control valve so that the water level in the sub-tank remains constant, thereby controlling the amount of water supplied to the sub-tank and the flow rate in the circulation line; and when the opening of the water level control valve remains below a predetermined value for a predetermined period of time, the control unit either stops the primary pure water apparatus or adjusts the opening of the water level control valve so that at least a portion of the primary pure water is returned in the circulation line.

[0010] In one aspect of the present invention, when the water level in the sub-tank falls below a predetermined value after the opening degree of the water level control valve remains below a predetermined value for a predetermined period of time, the control unit restarts the primary pure water device or adjusts the opening degree of the water level control valve so that the supply of primary pure water to the sub-tank is resumed.

[0011] In one aspect of the present invention, the control unit resumes determining whether the opening degree of the water level control valve is below a predetermined value after the primary pure water system is restarted or water supply to the sub-tank is resumed and the primary pure water system has been operated continuously for a predetermined period of time.

[0012] In one aspect of the present invention, the water level control valve is a three-way valve, and the primary pure water line is provided between the inlet of the three-way valve and the primary pure water device, and between the first outlet of the three-way valve and the sub-tank, and the circulation line is connected to the second outlet of the three-way valve.

[0013] In one aspect of the present invention, the water level adjustment valve includes a first valve provided in the primary pure water line and a second valve provided in the circulation line. [Effects of the Invention]

[0014] According to the present invention, the operating status of the customer's facility can be estimated from the amount of pure water replenished to the sub-tank, and the pure water device can be automatically started and stopped, thereby reducing running costs. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic configuration diagram of a water treatment system according to an embodiment of the present invention. [Figure 2] 10 is a graph showing an example of a change in the opening degree of a water level adjustment valve. [Figure 3] FIG. 10 is a schematic configuration diagram of a water treatment system according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment will be described with reference to the drawings.

[0017] 1, the water treatment system according to this embodiment includes a primary pure water system 12 and a subsystem 32. The primary pure water system 12 has a reverse osmosis (RO) device, an electrodeionization device, etc., and treats water to be treated (raw water) delivered from a tank 10 by a pump 11 to produce primary pure water. The primary pure water system 12 can be controlled by a control unit 50 to switch between operating and stopped.

[0018] The primary pure water produced by the primary pure water device 12 is sent to and stored in the sub-tank 30 via a primary pure water line 20 (20a, 20b). The primary pure water is also diverted by a three-way valve V1, which serves as a water level control valve, and can be returned to the tank 10 via a circulation line 22.

[0019] Specifically, one end of the primary pure water line 20a is connected to the primary pure water system 12, and the other end is connected to the inlet of the three-way valve V1. One end of the primary pure water line 20b is connected to the first outlet of the three-way valve V1, and the other end is connected to the sub-tank 30. One end of the circulation line 22 is connected to the second outlet of the three-way valve V1, and the other end is connected to the tank 10.

[0020] The valve opening (divert ratio) of the three-way valve V1 can be controlled by the control unit 50. In this embodiment, the greater the valve opening, the greater the divert ratio to the sub-tank 30. When the valve opening is 100%, the entire amount of primary pure water is sent to the sub-tank 30 (full amount passing). When the valve opening is 0%, the entire amount of primary pure water is returned to the tank 10 (full amount circulation).

[0021] Subsystem 32 has an ultraviolet oxidation device (UV device), an ion exchange device, an ultrafiltration membrane (UF membrane) device, etc., and processes the water to be treated (primary pure water) delivered from subtank 30 by pump 31 to produce ultrapure water.

[0022] The ultrapure water produced in the subsystem 32 is sent to a use point 33 (customer equipment) via a pipe 40, and unused ultrapure water is returned to the sub-tank 30 via a pipe 41.

[0023] The subtank 30 is provided with a water level meter (water level sensor) 34, which measures the water level inside the subtank 30. The control unit 50 acquires the measurement results of the water level meter 34 and adjusts the opening of the three-way valve V1 by PID control so that the water level inside the subtank 30 remains constant (within a certain range).

[0024] For example, when the measurement value of the water level meter 34 falls below a predetermined value (predetermined range), the control unit 50 increases the opening of the three-way valve V1 and increases the amount of primary pure water sent to the sub-tank 30. When the measurement value of the water level meter 34 rises above a predetermined value (predetermined range), the control unit 50 decreases the opening of the three-way valve V1 and decreases the amount of primary pure water sent to the sub-tank 30.

[0025] When the customer's equipment is not operating, the amount of ultrapure water used decreases (ultrapure water is no longer used), and the water level in the sub-tank 30 gradually rises. As the water level rises, the control unit 50 reduces the opening of the three-way valve V1, reducing the amount of primary pure water sent to the sub-tank 30. When the customer's equipment is not operating, the opening of the three-way valve V1 remains small. Taking advantage of this characteristic, if the opening of the three-way valve V1 (the value of the operation amount signal output to the three-way valve V1) remains below a predetermined value for a certain period of time, the control unit 50 determines that the customer's equipment is not operating and stops operation of the primary pure water system 12.

[0026] As an example, consider a case where the opening degree of the three-way valve V1 changes as shown in Fig. 2. The control unit 50 starts counting at time t1 when the opening degree of the three-way valve V1 falls below a predetermined value M, and when the state where the opening degree is equal to or less than M continues for a predetermined time T, the control unit 50 stops operation of the primary pure water system 12 at time t2 (= t1 + T).

[0027] When the customer's equipment is operating, the water level in the sub-tank 30 gradually drops as the ultrapure water is used. When the water level falls below a predetermined value, the control unit 50 determines that the customer's equipment is operating and starts operation of the primary pure water system 12. When operation of the primary pure water system 12 resumes, primary pure water is produced, and the control unit 50 adjusts the opening of the three-way valve V1 so that the water level in the sub-tank 30 remains constant.

[0028] After the primary pure water system 12 is restarted, the control unit 50 continues operation of the primary pure water system 12 for a certain period of time, and then resumes determining whether the opening degree of the three-way valve V1 is equal to or less than the predetermined value M. This prevents the primary pure water system 12 from being frequently switched on and off, and protects the primary pure water system 12.

[0029] In this way, in this embodiment, even if it is not possible to directly grasp the operating status of the customer's equipment, the operating status of the customer's equipment can be estimated from the opening degree of the three-way valve V1 and the primary pure water system 12 can be automatically started and stopped, thereby ensuring a stable supply of ultrapure water to the customer's equipment and reducing electricity running costs.

[0030] In the above embodiment, an example has been described in which a three-way valve V1 (diversion three-way valve) that serves as a flow dividing mechanism is used as a water level adjustment valve, but as shown in Fig. 3, a circulation line 22 may be branched off from the primary pure water line 20, a valve V2 may be provided between the branch point of the primary pure water line 20 and the sub-tank 30, and a valve V3 may be provided on the circulation line 22. The control unit 50 adjusts the opening of the valves V2 and V3 that serve as water level adjustment valves to control the flow division ratio.

[0031] If the opening of the valve V2 remains at or below a predetermined value for a certain period of time, the control unit 50 determines that the customer's facility is not operating and stops the operation of the primary pure water system 12.

[0032] In the above embodiment, an example was described in which the operation of the primary pure water system 12 is stopped when the apertures of the three-way valves V1 and V2 remain below a predetermined value for a certain period of time. However, instead of stopping the operation of the primary pure water system 12, the apertures of the three-way valves V1 and V2 may be set to 0% and the flow path of the primary pure water may be switched to the circulation line 22 to circulate the entire amount. Thereafter, when the water level in the sub-tank 30 falls below a predetermined value, the control unit 50 increases the apertures of the three-way valves V1 and V2 and resumes supplying the primary pure water to the sub-tank 30. After the supply of water to the sub-tank 30 is resumed, the operation of the primary pure water system 12 is continued for a certain period of time, and then the determination of whether the aperture of the three-way valve V1 is below the predetermined value M is resumed.

[0033] The present invention is not limited to the above-described embodiments, and the components can be modified and embodied in practice without departing from the spirit of the invention. Furthermore, various inventions can be created by appropriately combining multiple components disclosed in the above-described embodiments. For example, some components may be omitted from all the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined. [Explanation of symbols]

[0034] 12 Primary water purification equipment 30 Subtank 32 Subsystems 34 Water level gauge V1 three-way valve

Claims

1. a primary pure water device that treats the water to be treated and produces primary pure water for a pure water-using facility; a sub-tank for storing the primary pure water; a water level meter for measuring the water level of the sub-tank; a primary pure water line connecting the primary pure water device and the sub-tank; a circulation line for returning the primary pure water from the primary pure water line to the upstream side of the primary pure water device; a water level adjustment valve provided in the primary pure water line; a control unit that acquires the measurement result of the water level meter and adjusts the opening of the water level adjustment valve so that the water level in the sub-tank is constant, thereby controlling the amount of water sent to the sub-tank and the flow rate in the circulation line; Equipped with The control unit is characterized in that, when the opening degree of the water level control valve remains below a predetermined value for a predetermined period of time and determines that the pure water using equipment is not operating, the control unit stops the primary pure water device or adjusts the opening degree of the water level control valve so as to return at least a portion of the primary pure water in the circulation line.

2. The water treatment system described in claim 1, characterized in that when the control unit determines that the water level in the sub-tank falls below a predetermined value after the opening degree of the water level control valve has remained below a predetermined value for a predetermined period of time and the pure water using equipment is operating, it either restarts the primary pure water device or adjusts the opening degree of the water level control valve so that the supply of primary pure water to the sub-tank is resumed.

3. The water treatment system described in claim 2, characterized in that the control unit resumes determining whether the opening degree of the water level control valve is below a predetermined value after the primary pure water device is restarted or after water supply to the sub-tank is resumed and the primary pure water device is operated continuously for a predetermined period of time.

4. The water treatment system of any one of claims 1 to 3, characterized in that the water level control valve is a three-way valve, the primary pure water line is provided between the inlet of the three-way valve and the primary pure water device, and between a first outlet of the three-way valve and the sub-tank, and the circulation line is connected to a second outlet of the three-way valve.

5. 4. The water treatment system according to claim 1, wherein the water level adjustment valve comprises a first valve provided in the primary pure water line and a second valve provided in the circulation line.

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