JP7679718B2 - Reverse osmosis membrane system and its operating method - Google Patents

Description

The present invention relates to a reverse osmosis membrane system and its operating method.

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. Also, the second pressure pump is inverter controlled so that the permeated water flow rate of the second RO device becomes a target flow rate.

JP 2013-66840 A.

When starting up a pump that supplies water to a reverse osmosis membrane device, water hammer can occur. Conventionally, water hammer has been suppressed by starting up an inverter-equipped pump at a low frequency, but noise generated by the inverter can cause malfunctions, making it difficult to completely suppress water hammer.

The objective of the present invention is to provide a reverse osmosis membrane system and an operating method thereof that reliably prevents water hammer when starting a pump that supplies water to a reverse osmosis membrane device and ensures stable pump operation.

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

In one aspect of the present invention, an orifice is provided in the bypass line.

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 the pump was started, and the valve is opened after the predetermined time has elapsed.

In the present invention, in a reverse osmosis membrane system in which the 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 is provided with a main line having a valve and a bypass line that bypasses the valve. In the initial stage 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.

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 no longer necessary, stable pump operation at a constant frequency is possible, and pump malfunctions are reduced.

1 is a configuration diagram of a reverse osmosis membrane system according to an embodiment.

The embodiment will be described below with reference to FIG.

In FIG. 1, the water to be treated is supplied to the RO device 8 via pipe 1, pump 2, pipe 3, valve 4, and pipe 7, and the permeated water is taken out via pipe 9. The concentrated water from the RO device 8 is taken out via pipe 10.

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.

In a reverse osmosis membrane system configured in this manner, when the pump 2 is first started, that is, until a predetermined time has elapsed since the pump 2 was started, the valve 4 in the main line is closed and water is passed through the bypass line 5 to the RO device 8, and after the predetermined time has elapsed, the valve 4 is opened. 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 malfunctions of the pump 2 are reduced. The above-mentioned predetermined time is preferably 2 to 30 seconds, particularly 5 to 20 seconds, and especially about 10 seconds, but is not limited to this.

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, an orifice 6 is provided in the bypass line 5, but a flow path resistance member other than an orifice may be provided. Also, if the pipe diameter of the bypass line is small, a flow path resistance member such as an orifice may be omitted.

2 pump 4 valve 5 bypass line 6 orifice 8 RO device

Claims (2)

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. The method of claim 1, wherein the predetermined time is between 5 and 20 seconds.

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