JP2001113136A - Reverse osmosis treating device and water production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reverse osmosis treating device having a simple constitution for effectively preventing deterioration of physical properties of the reverse osmosis membrane by preventing the reverse osmosis membrane module from being rapidly exerted pressure at a start time of the operation. SOLUTION: This device is provided with a bypass flow path 3 provided on a discharge side of a plunger pump 1 for raising raw water to a specified pressure, and feeding it to the reverse osmosis membrane module 2, and bypassing the feed water discharged from the pump 1 with respect to the reverse osmosis membrane module 2, and a needle valve type or a glove valve type flow rate control valve 4 for adjusting a bypass quantity of raw water is provided in the bypass flow path. At a start time of the operation of the pump 1, the flow rate control valve is performed diaphragm control from a full open state to a full closed state over a specified time, and the pressure of raw water fed to the reverse osmosis membrane module 2 is gradually raised.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a reverse osmosis treatment apparatus for obtaining permeated water of raw water using a reverse osmosis membrane module,
For example, the present invention relates to a reverse osmosis treatment apparatus and a water freshening method having a simple configuration capable of effectively preventing physical degradation of the reverse osmosis membrane module due to raw water pressurized using a plunger pump.

[0002]

[Related background art] Generation of freshwater from seawater / brine,
Alternatively, a reverse osmosis treatment device equipped with a reverse osmosis membrane module is used for generating clean water from river water.
Basically, as shown in FIG. 4, this type of apparatus raises a supply water (sea water), which has been subjected to pretreatment such as sterilization and removal of turbid components, to a predetermined pressure via a pump 1 to perform a reverse osmosis membrane. module·
The water is supplied to the unit 2 and the permeated water (fresh water) permeated by the reverse osmosis action in the reverse osmosis membrane module unit 2 is obtained.

A plurality of reverse osmosis membrane module units 2 are provided in two stages, the permeated water is obtained from a first stage bank (reverse osmosis membrane module unit 2), and the first stage bank is provided. Pressure of the concentrated water discharged from
It is also considered that the efficiency of permeate generation is increased by supplying the permeate to the second-stage bank and obtaining the permeate from the second-stage bank.

[0004] Reverse osmosis membrane module unit 2
For example, as shown in FIG. 5, a plurality of reverse osmosis membrane modules 20 in which a plurality of reverse osmosis membrane elements 10 are connected in series and housed in a cylindrical pressure vessel 21 are provided in parallel. Incidentally, each reverse osmosis membrane element 10 is, for example, shown in FIG.
As shown in FIG. 5, a bag-shaped reverse osmosis membrane 13 containing a flow path material 12 is spirally wound around a center pipe 11 via a mesh spacer 14, and a brine seal 15 is provided at one end thereof. . Then, each reverse osmosis membrane element 10 guides raw water (seawater) of a predetermined pressure supplied from the brine seal 15 side into the bag-like reverse osmosis membrane 13 through the flow path material 12 in order, and reverse osmosis by reverse osmosis action. The permeated water (fresh water) that has passed through the membrane 13 is taken out through the center pipe 11.

[0005] The reverse osmosis membrane module 20 passes between the center pipes 11 of the respective reverse osmosis membrane elements 10 as shown in FIG.
As shown in FIG. 5, the inside of the pressure vessel 21 is partitioned by the brine seal 15 while being sequentially connected via the joint 22. Raw water (seawater) introduced from a supply water port 23 provided on one end side of the pressure vessel 21 is guided into the reverse osmosis membrane 12 of each reverse osmosis membrane element 10 in order, and the permeated water is introduced into the center pipe 11. obtain. This permeated water is supplied to the pressure vessel 2
It is taken out from the permeated water port 24 provided on the other end side of 1 and connected to the center pipe 11. The remaining supply water (seawater) that has not passed through each reverse osmosis membrane 13, that is, concentrated water (seawater), is discharged from a discharge port 25 provided at the other end of the pressure vessel 21.

[0006]

When such a reverse osmosis treatment apparatus is operated, particularly when starting the operation, the raw water (seawater) supplied to the reverse osmosis membrane module unit 2 with the start of the pump 1 is increased. The pressure is rapidly increased. Incidentally, the pressure of the supply water when the reverse osmosis membrane module unit 2 exhibits the reverse osmosis action, that is, the operating pressure of the osmosis membrane module unit 2 is extremely high, for example, about 6.0 Mp. When such high-pressure raw water (seawater) is rapidly added to the osmosis membrane module unit 2, the pressure shock may deteriorate the physical properties of the reverse osmosis membrane 12. Specifically, a rupture may occur in the reverse osmosis membrane 12 due to a sudden pressure of the raw water, and a problem such as leakage of the raw water from the fold may occur. Such a leak of the raw water causes a decrease in, for example, a desalination rate in the osmosis membrane module unit 2, and reduces the reverse osmosis treatment capacity.

The present invention has been made in view of such circumstances, and an object of the present invention is to prevent sudden application of pressure to the osmosis membrane module at the start of operation, and to degrade the physical properties of the reverse osmosis membrane. It is an object of the present invention to provide a reverse osmosis treatment apparatus having a simple configuration capable of effectively preventing the occurrence of the reverse osmosis. In particular, the present invention
Even if a relatively inexpensive plunger-type pump is used as a pump for raising raw water to a predetermined pressure, for example, a sudden increase in pressure of supply water supplied to the permeable membrane module can be simplified and effectively performed. It is an object of the present invention to provide a reverse osmosis treatment device having a simple structure that can be prevented.

[0008] Another object of the present invention is to provide a fresh water producing method in which fresh water is stably generated using the reverse osmosis treatment apparatus having the above-mentioned structure.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention relates to a reverse osmosis treatment apparatus for supplying raw water to a reverse osmosis membrane module to obtain the permeated water. A reverse flow path is provided on a discharge side of a pump for increasing and supplying the reverse osmosis membrane module to the reverse osmosis membrane module. The bypass flow path bypasses supply water discharged from the pump to the reverse osmosis membrane module. It is characterized by incorporating a flow control valve for adjusting the bypass amount of raw water.

That is, the reverse osmosis treatment device according to the present invention adjusts the bypass amount of the supply water discharged from the pump by using the flow control valve interposed in the bypass passage provided on the discharge side of the pump. And the pressure of the raw water supplied to the reverse osmosis membrane module is adjusted.
Preferably, a plunger pump or a spiral pump is used as the pump, and a needle valve or a globe valve is used as the flow control valve. And as described in claim 3,
After the pump starts operating, the flow control valve gradually controls the throttle from a fully open state to a fully closed state.

Further, the reverse osmosis treatment apparatus according to the present invention uses seawater or brackish water as raw water,
A fresh water producing method for producing fresh water using the reverse osmosis treatment apparatus having the above-described configuration as described in claim 5, which is suitable for a system for obtaining fresh water as the permeated water through the reverse osmosis membrane module. Is provided.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A reverse osmosis treatment apparatus according to one embodiment of the present invention will be described below with reference to the drawings. This reverse osmosis treatment apparatus is provided for the generation of fresh water from seawater / brine water, or the generation of clean water from rivers / lake waters, and is schematically configured as shown in FIG. 1, for example. You. That is, raw water (seawater) that has been subjected to pretreatment such as sterilization and turbid component removal is supplied to the reverse osmosis membrane module unit 2 after being raised to a predetermined pressure via the pump 1. The pump 1 is a relatively inexpensive plunger type pump (plunger pump) capable of increasing the pressure of raw water to, for example, about 60 MPa. Reverse osmosis membrane module unit 2
By receiving raw water raised to a predetermined pressure through such a pump 1, permeated water (fresh water) that has passed through the reverse osmosis membrane by reverse osmosis is obtained.

On the discharge side of the plunger pump 1, there is provided a bypass flow path 3 which can supply water discharged from the pump 1 to the reverse osmosis membrane module unit 2 and return to the supply source side. Is provided. The flow control valve 4 interposed in the bypass flow path 3 is formed of a needle valve type or globe valve type control valve, and plays a role of controlling the bypass flow rate of the supply water discharged from the pump 1. In particular, the needle valve type or globe valve type flow control valve 4 gradually changes from its fully opened state to its fully opened state for a predetermined time under the control of the control unit 5 in conjunction with the operation start (startup) of the pump 1. The aperture is controlled to the closed state. More specifically, when the operation of the pump 1 is started,
The control unit 5 transitions the flow control valve 4 (bypass passage 3) from the fully open state to the fully closed state by gradually narrowing the valve opening of the flow control valve 4 over about 200 seconds. Has become.

The control unit 5 may operate, for example, the pump 1 and the flow control valve 4 at the same time, or the raw water obtained by a pressure detecting means (not shown) installed downstream of the pump 1. Flow control valve 4 based on pressure value
The valve opening may be controlled. Thus, by such a flow control valve 4, the bypass flow rate of the raw water discharged by the pump 1 after the operation of the pump 1 is started is controlled by the flow control valve 4.
According to the reverse osmosis treatment device configured to gradually narrow down the raw water, even if the plunger pump 1 suddenly discharges high-pressure raw water with the start of its operation, the raw water is bypassed. Since the water is discharged through the flow path 3, high-pressure raw water is not suddenly applied to the reverse osmosis membrane module unit 2. Since the pressure of the raw water applied to the reverse osmosis membrane module unit 2 is gradually increased as the flow rate control valve 4 is narrowed, a pressure shock is applied to the reverse osmosis membrane of the reverse osmosis membrane module unit 2. Therefore, the physical properties of the reverse osmosis membrane can be stably maintained. That is, it is possible to effectively prevent deterioration of physical characteristics of the reverse osmosis membrane, such as occurrence of a fold.

Further, in the case of the plunger pump 1, it is unavoidable that the pressure of the raw water discharged from the pump 1 pulsates to some extent due to its structural properties. However, in the present apparatus, the bypass flow rate of the raw water discharged from the plunger pump 1 is adjusted by using the flow control valve 4 of the needle valve type or the globe valve type, whereby the supply water supplied to the reverse osmosis membrane module unit 2 is adjusted. Since the pressure is adjusted, the supply pressure can be smoothly changed. Therefore, for example, as shown as the characteristic A in FIG. 3, it is possible to gradually increase the pressure of the raw water applied to the reverse osmosis membrane module unit 2 with the activation of the plunger pump 1.

By the way, when a ball type regulating valve is interposed in the bypass flow path and the bypass is controlled, the flow rate cannot be gradually controlled in the ball type regulating valve. As shown, the pressure of the raw water applied to the reverse osmosis membrane module unit 2 changes rapidly with the switching. Therefore, even though the bypass channel 3 is provided, the pressure of the raw water applied to the reverse osmosis membrane module unit 2 cannot be smoothly and variably controlled. Therefore, by inserting a needle valve type or globe valve type flow control valve 4 in the bypass flow path 3 and gradually adjusting the bypass flow rate, raw water added to the reverse osmosis membrane module unit 2 simply and effectively. Can be controlled.

When a centrifugal pump is used as the pump 1, the apparatus may be configured as shown in FIG. 2, for example. That is, the centrifugal pump 1b basically adjusts the discharge pressure and the flow rate by providing a flow control valve on the discharge side, but it is necessary to secure a minimum flow rate for the centrifugal pump 1 to operate. And cannot be reduced below that.

Therefore, in this embodiment, as shown in FIG. 2, separately from a flow control valve 4c for adjusting the pressure and flow rate of raw water supplied from the centrifugal pump 1b to the reverse osmosis membrane module unit 2b. A bypass flow path 3b is provided to ensure the minimum flow rate of the centrifugal pump 1, and a flow control valve 4b is provided in the bypass flow path 3b. The spiral pump 1 is started while the flow control valve 4b is throttled to the minimum flow rate of the spiral pump 1, and thereafter, the control unit 5b performs control to gradually reduce the flow control valve 4b from fully open to fully closed. By controlling the flow rate control valve 4c to be gradually opened by the control unit 5 in conjunction with the narrowing down of the flow rate control valve 4b, the reverse osmosis membrane module unit 2b is ensured while ensuring the minimum flow rate of the centrifugal pump 1.
Gradually increase the pressure of raw water supplied to

By controlling the flow control valves 4b and 4c in this manner, an excessive load is hardly applied to the centrifugal pump 2b, and a sudden pressure is hardly applied to the reverse osmosis membrane module unit 2b. It is possible to prevent physical deterioration such as breakage of the reverse osmosis membrane, and it is possible to achieve the same effect as the above embodiment. Thus, according to the reverse osmosis treatment device having the configuration in which the needle valve type or the globe valve type flow control valve is interposed in the bypass flow path as described above, the problem of pressure loss at the time of steady operation is not caused. Since the problem of pressure shock at the time of startup can be effectively avoided, a great effect in practical use can be achieved, for example, the physical characteristics of the reverse osmosis membrane can be simply and effectively prevented from deteriorating. In addition, the discharge amount can be controlled relatively smoothly, but the pressure of raw water supplied to the reverse osmosis membrane module unit can be smoothly changed without using an expensive inverter type high pressure pump. There is an advantage that the configuration price can be reduced.

The present invention is not limited to the above embodiment. For example, the present invention is similarly applicable to an apparatus configured to simultaneously supply raw water from a pump to a plurality of reverse osmosis membrane module units provided in parallel. Also, the time required for the needle valve type or globe valve type flow control valve to transition from the fully open state to the fully closed state may be determined according to the specifications of the reverse osmosis membrane element constituting the reverse osmosis membrane module unit. Good thing. Further, the configuration of the control unit that performs the control is not particularly limited. Needless to say, the present invention can be similarly applied to an apparatus for generating clean water from river water or lake water. Others
The present invention can be implemented with various modifications without departing from the scope of the invention.

[0021]

As described above, according to the present invention, the pressure of raw water pressurized by using a pump is adjusted by using a flow control valve provided in a bypass flow path to adjust the bypass flow rate. At the start of operation of the pump, the flow control valve is gradually reduced from the fully open state to the fully closed state, so that the pressure of raw water applied to the reverse osmosis membrane module can be gradually changed. As a result, practically significant effects such as simple and effective prevention of deterioration of the physical properties of the reverse osmosis membrane module can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a reverse osmosis treatment device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of a reverse osmosis treatment device according to another embodiment of the present invention.

FIG. 3 is a diagram showing a change in raw water pressure due to the action of a flow control valve when the apparatus is started.

FIG. 4 is a diagram showing a basic schematic configuration of a reverse osmosis treatment device.

FIG. 5 is a diagram showing a general structure of a reverse osmosis membrane module.

FIG. 6 is a diagram showing a configuration example of a reverse osmosis membrane element incorporated in a reverse osmosis membrane module.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Plunger pump 1b Spiral pump 2,2b Reverse osmosis membrane module unit 3,3b Bypass flow path 4,4b, 4c Flow control valve (needle valve or globe valve) 5,5b Control unit

Claims (5)

[Claims] 1. A reverse osmosis treatment apparatus for supplying raw water to a reverse osmosis membrane module to obtain permeated water, comprising: a pump for increasing the raw water to a predetermined pressure and supplying the raw water to the reverse osmosis membrane module; A bypass flow path provided on the discharge side to bypass raw water discharged from the pump to the reverse osmosis membrane module, and a flow control valve provided in the bypass flow path to adjust a bypass amount of the raw water. A reverse osmosis treatment device, comprising: 2. The reverse osmosis treatment device according to claim 1, wherein the pump comprises a plunger pump or a spiral pump, and the flow control valve comprises a needle valve or a globe valve. 3. The reverse osmosis treatment device according to claim 1, wherein the flow control valve is a throttle valve that controls a valve opening in a fully open state to a fully closed state after the operation of the pump is started. 4. The reverse osmosis treatment device according to claim 1, wherein the supply water is seawater or brackish water. 5. A fresh water producing method, wherein fresh water is obtained by using the reverse osmosis treatment device according to claim 1.