Reverse osmosis membrane system and its operating method

Abstract

To provide a reverse osmosis membrane system and an operation method of the same where water hammering at the starting up of a pump feeding water to a reverse osmosis membrane device is surely prevented and the operation of the pump can be stabilized.SOLUTION: In an operation method of a reverse osmosis membrane system,: water to be treated is fed to an RO device 8 via piping 1, a pump 2, piping 3, a valve 4 and piping 7 and permeated water is discharged via piping 9; the concentrated water of the RO device 8 is discharged by piping 10; a bypass line 5 with an orifice 6 is installed so as to bypass the valve 4; and the valve 4 is closed before passing a prescribed time from the starting up of the pump 2 and the valve 4 is opened after passing a prescribed time.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a reverse osmosis membrane system and a method for operating the same. [Background technology]

[0002] In a reverse osmosis membrane system having a reverse osmosis membrane device (RO device), raw water is pressurized by a pressure pump and supplied to the RO device. Patent Document 1 describes a water treatment system in which feed water is pressurized by a first pressure pump and supplied to a first RO device, and the permeated water is pressurized by a second pressure pump and supplied to a second RO device to obtain permeated water. In Patent Document 1, the first pressure pump is inverter controlled so that the permeated water flow rate of the first RO device becomes a target flow rate. Moreover, the second pressure pump is inverter controlled so that the permeated water flow rate of the second RO device becomes a target flow rate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-66840 A. Summary of the Invention [Problem to be solved by the invention]

[0004] When starting up a pump that supplies water to a reverse osmosis membrane device, water hammer can occur. Conventionally, when starting up an inverter-equipped pump, water hammer is suppressed by starting at a low frequency, but malfunctions can occur due to noise generated by the inverter, making it impossible to completely suppress water hammer.

[0005] An object of the present invention is to provide a reverse osmosis membrane system and an operating method thereof in which water hammer is reliably prevented when a pump for supplying water to a reverse osmosis membrane device is started and the operation of the pump is stable. [Means for solving the problem]

[0006] The reverse osmosis membrane system of the present invention is a reverse osmosis membrane system in which water to be treated is pressurized by a pump and passed through a water supply line to a reverse osmosis membrane device, the water supply line including a main line having a valve and a bypass line that bypasses the valve.

[0007] In one aspect of the present invention, the bypass line is provided with an orifice.

[0008] The method for operating the reverse osmosis membrane system of the present invention is a method for operating the reverse osmosis membrane system of the present invention, characterized in that the valve is closed until a predetermined time has elapsed since starting the pump, and the valve is opened after the predetermined time has elapsed. Effect of the Invention

[0009] In the present invention, in a reverse osmosis membrane system in which water to be treated is pressurized by a pump and passed through a reverse osmosis membrane device via a water supply line, the water supply line includes a main line having a valve and a bypass line that bypasses the valve. At the beginning of pump startup, that is, until a predetermined time has elapsed since the pump was started, the valve of the main line is closed and water is passed through the bypass line, and after the predetermined time has elapsed, the valve is opened.

[0010] According to the present invention, it is possible to suppress a sudden increase in the water flow rate and water pressure when the pump is started, and water hammer is reliably prevented. In addition, since inverter control of the pump to prevent water hammer is not required, stable pump operation at a constant frequency is possible, and pump malfunctions are reduced. [Brief description of the drawings]

[0011] [Figure 1] 1 is a configuration diagram of a reverse osmosis membrane system according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment will be described with reference to FIG.

[0013] In Fig. 1, water to be treated is supplied to an RO device 8 via a pipe 1, a pump 2, a pipe 3, a valve 4, and a pipe 7, and permeated water is taken out via a pipe 9. Concentrated water from the RO device 8 is taken out by a pipe 10.

[0014] A bypass line (piping) 5 is provided to bypass the valve 4 and connect the pipes 3 and 7, and an orifice 6 is provided in the bypass line 5. The pump 2 and the valve 4 are controlled by a controller 11. In this embodiment, the pipe 3, the valve 4, and the pipe 7 form a main line.

[0015] In the reverse osmosis membrane system configured as above, the valve 4 of the main line is closed at the beginning of the start of the pump 2, that is, until a predetermined time has elapsed since the start of the pump 2, and water is passed through the RO device 8 from the bypass line 5, and the valve 4 is opened after the predetermined time has elapsed. This makes it possible to suppress a sudden increase in the amount of water passing through and the water pressure when the pump 2 is started, and reliably prevents water hammer. In addition, since it is not necessary to control the rotation speed of the pump 2 with an inverter, the pump 2 can be operated stably by rotating the pump 2 at a constant frequency, and the malfunction of the pump 2 is reduced. The predetermined time is preferably 2 to 30 seconds, particularly 5 to 20 seconds, and particularly preferably about 10 seconds, but is not limited thereto.

[0016] The above embodiment is one example of the present invention, and the present invention may be embodied in other forms. For example, in the above embodiment, the orifice 6 is provided in the bypass line 5, but a flow path resistance member other than the orifice may be provided. In addition, when the pipe diameter of the bypass line is small, the flow path resistance member such as the orifice may be omitted. [Explanation of symbols]

[0017] 2. Pump 4 Valves 5. Bypass Line 6 Orifice 8 RO device

Claims

1. A method for operating a reverse osmosis membrane system in which water to be treated is pressurized by a pump and passed through a water supply line to a reverse osmosis membrane device, comprising: the water supply line includes a main line having a valve, a bypass line that bypasses the valve, and an orifice provided in the bypass line; The valve is closed until a predetermined time (between 2 and 30 seconds) has elapsed since the pump was started, and then the valve is opened after the predetermined time has elapsed. A method for operating a reverse osmosis membrane system comprising:

2. A method for operating a reverse osmosis membrane system according to claim 1, wherein the predetermined time is between 5 and 20 seconds.

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