JPH0768257A - Fresh water producing apparatus - Google Patents

Abstract

PURPOSE:To obtain fresh water in such a state that the production amt. of water is stabilized, to enhance the coefficient of utilization of raw water and to facilitate maintenance and control by controlling the suppry pressure of water to a reverse osmosis membrane device by controlling the opening degree of a flow control valve on the basis of the detection signal of a flow rate detector. CONSTITUTION:A part of the raw water supplied to a reverse osmosis membrane device 8 transmits through a reverse osmosis membrane to be taken out as fresh water from a transmitted water pipe 24 but, at this time, the amt. of transmitted water is measured by a flow rate detector 26 to be compared with a preset amt. When the amt. of transmitted water is more than the preset amt., a control signal is sent to a flow control valve 14 to increase the opening degree of the valve 14 and the pressure of the raw water supplied to the reverse osmosis membrane device 8 is reduced to reduce the amt. of transmitted water. When the amt. of transmitted water is less than the preset amt., a control signal is sent to the flow control valve 14 to reduce the opening degree of the valve 14 and the pressure of the raw water supplied to the reverse osmosis membrane 8 is increased to increase the amt. of transmitted water. By this constitution, the amt. of transmitted water can be held to an almost preset desired value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing fresh water such as drinking water, and more particularly to an apparatus for producing fresh water using a reverse osmosis membrane apparatus suitable for use in isolated islands.

[0002]

2. Description of the Related Art Conventionally, in a drinking water manufacturing apparatus using a reverse osmosis membrane, the operating pressure of a reverse osmosis pump is constant.
There is no problem if you always use raw water with the same salt concentration (for example, seawater), but when raw water with a lower salt concentration becomes available (for example, collect rainwater, mix this rainwater with seawater, and reverse When the raw water of the osmosis membrane device is used), the reverse osmotic pressure of the raw water becomes low, so the production water volume increases sharply even though the pump pressure is constant, and There is a possibility that the reverse osmosis membrane may be clogged because the capacity is exceeded or the amount of concentrated water decreases. Further, in the conventional reverse osmosis membrane device, the raw water supplied to the reverse osmosis membrane device requires pretreatment such as coagulation sedimentation or filtration in advance, but most of the raw water pretreated in this way is
It is discarded as concentrated water generated during reverse osmosis membrane treatment.
Therefore, the load of the pretreatment facility is large and the utilization efficiency of raw water is low.

On the other hand, a facility for producing drinking water using a reverse osmosis membrane device is used in a place where the water source is scarce, but it is desirable to operate with the minimum energy. Therefore, not only seawater but also salt concentration is better than seawater. It is desirable to have a device that can use seawater and brackish water mixed with low-rainwater.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems. Even if the salt concentration in the raw water changes, the reverse osmosis membrane device produces a constant amount of water, thereby improving the Prevents clogging of the osmosis membrane and, when the concentration of concentrated water salt is low, reuses this as raw water to increase the effective utilization rate of raw water and reduce the load of pretreatment (pretreatment such as turbidity). The object of the invention is to provide a fresh water producing apparatus that solves the above problems.

[0005]

In order to achieve the above object, in the present invention, a raw water tank and a pressurizing pump are interposed, and the raw water in the raw water tank is fed under pressure to a reverse osmosis membrane device. It consists of a feed pipe, a reverse osmosis membrane device that separates the pressurized and fed raw water into permeated water and concentrated water, and a circulation pipe that returns the concentrated water taken out from the reverse osmosis membrane device to a raw water tank. In the fresh water producing apparatus, a flow rate detector for detecting the flow rate of permeated water is provided in the permeated water take-out part of the reverse osmosis membrane device, and a flow rate control valve is provided in the circulation pipe to detect the flow rate detector. The permeated water amount of the reverse osmosis membrane device is adjusted to a predetermined amount by controlling the opening of the flow rate control valve based on the signal to adjust the supply water pressure of the reverse osmosis membrane device. A concentration detector to detect A cutoff valve is provided between the flow control valve of the circulation pipe and the raw water tank, and a discharge pipe provided with a discharge valve is connected between the flow control valve of the circulation pipe and the cutoff valve, or In place of the shutoff valve, a three-way valve having a discharge port is additionally provided, and when the salt concentration of the raw water detected by the concentration detector exceeds a predetermined value, the shutoff valve is closed based on the signal of the concentration detector. It includes opening the discharge valve or opening the discharge port of the three-way valve to discharge the concentrated water from the discharge pipe.

Further, according to the present invention, a solar cell module is used as a power source of a fresh water producing apparatus, and the solar cell module is provided with a water collecting means, and the water collecting means and the raw water tank are connected by a water pipe. It is a fresh water producing apparatus for supplying rainwater received on the upper surface of a module to a raw water tank via the water collecting means and a water conduit.

[0007]

The present invention will be described in detail below with reference to examples.

(Embodiment 1) FIG. 1 is a flow chart showing an embodiment of the present invention, in which 2 is a raw water tank for storing desalinated seawater and the like. The raw water in the raw water tank is fed to the reverse osmosis membrane device 8 by the pressurizing pump 6 interposed in the feed pipe 4, where a part of the raw water becomes desalted permeate, and the take-out part of the device 8 While being taken out from the tank 10, the rest is returned as concentrated water to the raw water tank 2 through the circulation pipe 12. The circulation pipe 12 is provided with a flow rate control valve 14 and a shutoff valve 16 sequentially from the reverse osmosis membrane device 8 side,
These valves 14 and 16 are operated by electric signals.

Further, one end of a discharge pipe 18 is connected to the circulation pipe 12 between the valves 14 and 16. A discharge valve 20 is provided in the discharge pipe 18 and is operated by an electric signal.

Reference numeral 22 denotes a concentration detector (in this example, an electric conductivity meter) interposed in the feed pipe 4 between the raw water tank 2 and the pressurizing pump 6, and the concentration detector in the raw water fed in the pipe 4 The salt concentration is detected, and an electric signal corresponding to the salt concentration is sent to the shutoff valve 16 and the discharge valve 20, whereby both valves 1
6, 20 open and close.

Reference numeral 24 is a permeated water pipe connected to the permeated water take-out portion 10, and a flow rate detector 26 is interposed therein. The detector 26 detects the flow rate of the permeated water flowing through the permeated water pipe 24 and sends an electric signal corresponding to the flow rate to the flow rate control valve 14, thereby adjusting the opening degree of the flow rate control valve 14. The flow rate of the concentrated water returned to the raw water tank 2 through the circulation pipe 12 is controlled.

Next, using the fresh water producing apparatus having the above-mentioned structure, as an example, the case of desalinating raw water in which rainwater is mixed with seawater will be explained. After being done, it is stored in the raw water tank 2. In this case, the salt concentration of the raw water in the tank 2 is lower than that of seawater because rainwater is mixed. The raw water in the raw water tank 2 is then pressure-fed by the pressure pump 6 to the reverse osmosis membrane device 8. At this time, the salt concentration in the raw water fed to the reverse osmosis membrane device 8 is detected by the concentration detector 22. It is measured and compared with a preset salt concentration (in this example, salt concentration of seawater), and when it is lower than the set concentration, the shutoff valve 1
A control signal is sent from the detector 22 to both valves 16 and 20 such that 6 is "open" and discharge valve 20 is "closed".

The raw water sent to the reverse osmosis membrane device 8 is
A part of the permeated water passes through the reverse osmosis membrane and becomes desalinated water, which is taken out from the permeated water pipe 24. At this time, the permeated water amount is measured by the flow rate detector 26 and compared with the preset permeated water amount. Is performed. Then, when the amount of permeated water is larger than the set amount of permeated water, a control signal is sent from the detector 26 to the flow rate control valve 14 to increase the opening degree of the valve 14. As a result, the raw water pressure (supply water pressure) sent to the reverse osmosis membrane device 8 decreases, and the amount of permeated water decreases. Further, when the amount of permeated water is smaller than the set amount of permeated water, a control signal is sent from the detector 26 to the flow rate control valve 14 to reduce the opening degree of the valve 14. As a result, the raw water pressure fed to the reverse osmosis membrane device 8 increases, and the amount of permeated water increases. In this way, the amount of permeated water is maintained at a preset desired value.

On the other hand, the concentrated water returned from the reverse osmosis membrane device 8 flows into the raw water tank 2 with the salt concentration increased,
This gradually increases the salt concentration of the raw water in the raw water tank 2. Then, when the value of the salt concentration measured by the concentration detector 22 exceeds a preset value (in this example, the salt concentration of seawater), a signal is sent from the concentration detector 22, which causes the shutoff valve 16 to operate. Upon closing, the discharge valve 20 is opened, and the concentrated water (higher salt concentration than seawater) from the reverse osmosis membrane device 8 is discharged out of the system through the discharge pipe 18. In this state, the raw water tank 2 is always supplied with the pretreated raw water, and the concentrated water is discharged from the discharge pipe 18 without being circulated to the raw water tank 2. It is processed by an expression.

Further, when the raw water is continuously supplied to the raw water tank 2 in this state and the salt concentration measured by the concentration detector 22 becomes lower than the set value, the valve 16 is opened by the same procedure as described above. At the same time, the valve 20 closes and returns to the initial state. Even in this case, the amount of permeated water is determined by the flow rate detector 26.
And is kept constant by the operation of the flow rate control valve 14.

In the above embodiment, as raw water,
The case of treating water in which rainwater is mixed with seawater and therefore having a lower salt concentration than seawater has been described. However, in the case of always treating seawater using the fresh water producing apparatus, the shutoff valve 16 is closed, and It is also possible to manufacture the fresh water while constantly discharging the concentrated water of the reverse osmosis membrane device 8 to the outside of the system by opening the discharge valve 20. A resistivity meter or the like can also be used as the concentration detector. Further concentration detector 2
The value preset in 2 is not limited to the salt concentration of seawater and can be set to any value.

Further, in the above-described embodiment, the discharge valve 20 is provided in the discharge pipe 18 and the shutoff valve 16 is provided in the circulation pipe 12, respectively. Instead of the shutoff valve 16, a three-way valve having a discharge port is additionally provided. Even if the flow path of the three-way valve is switched by the signal of the concentration detector, the same control as in the above embodiment can be performed, and in this case, the discharge valve 20 can be omitted.

(Embodiment 2) FIG. 2 shows another embodiment of the present invention, in which a solar cell is incorporated in the fresh water producing apparatus of the present invention.

In FIG. 2, reference numeral 30 denotes a rectangular parallelepiped raw water tank on which a reverse osmosis membrane device 32 is mounted.
Reference numeral 34 denotes a feed pipe, which operates the pressurizing pump 36 to feed the raw water in the raw water tank 30 to the reverse osmosis membrane device 3
2, the fresh water production is performed, and the valves, detectors, and the like are omitted, but these constitute the fresh water production apparatus of the first embodiment.

A gantry 38 is provided on the upper surface of the raw water tank 30, and a solar cell module 40, which is a power source of the fresh water producing apparatus, is attached to the gantry 38 with a predetermined inclination with respect to a horizontal plane. Further, water collecting grooves 42 are formed at both ends and the lower end of the solar cell module 40, and the rainwater received by the inclined surface of the solar cell module 40 is collected in the water collecting grooves 42, and then the water conduit pipe. 44,4
It flows through 6 to the raw water tank 30. Reference numeral 48 is a supply pipe for supplying the turbidity-treated seawater to the raw water tank.

Although seawater and rainwater are used as raw water in the above embodiment, various kinds of water such as river water and can water can be used.

The configuration of this example simplifies the collection of rainwater and reduces the area required to install this device.
Particularly, it is preferable for producing drinking water in remote islands.

[0023]

The device of the present invention has a control function corresponding to changes in salt concentration of raw water, so that fresh water can be obtained in a state where the amount of produced water is stable. In addition, the utilization rate of raw water is high and maintenance is easy.

By using an apparatus having such a function, for example, on a remote island in the south where there is a large amount of rainfall while utilizing both rainwater and seawater, it becomes possible to supply fresh water at a stable supply amount for a long period of time. Further, unlike other filtration membranes, reverse osmosis membranes can surely remove bacteria, so that hygienic reliability becomes high, and hygiene maintenance and management becomes easy, especially when producing drinking water.

[Brief description of drawings]

FIG. 1 is a flow chart showing an embodiment of the present invention.

FIG. 2 is a schematic perspective view showing another embodiment of the present invention.

[Explanation of symbols]

 2 Raw water tank 4 Supply pipe 6 Pressurizing pump 8 Reverse osmosis membrane device 10 Extraction part 12 Circulation pipe 14 Flow rate control valve 16 Shutoff valve 18 Discharge pipe 20 Discharge valve 22 Concentration detector 24 Permeate pipe 26 Flow rate detector 30 Raw water tank 32 reverse osmosis membrane device 40 solar cell module

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Naomi Kawato 2-5-14 Minamisuna, Koto-ku, Tokyo Inside the Takenaka Corporation Technical Research Institute (72) Inventor Yuji Hayashi 1-4 Kawagishi, Toda City, Saitama Prefecture No. 9 Organo Research Institute (72) Inventor Mari Koide 1-4-9 Kawagishi, Toda City, Saitama Organo Research Institute (72) Inventor Hiroshi Takeuchi 5 Hongo, Bunkyo-ku, Tokyo No. 5-16 Organo Corporation

Claims (3)

[Claims] 1. A raw water tank, a feed pipe for interposing a pressure pump to feed the raw water in the raw water tank to a reverse osmosis membrane device under pressure, and the raw water fed under pressure is concentrated with permeate. A reverse osmosis membrane device that separates and extracts water, and a circulating water pipe that returns concentrated water extracted from the reverse osmosis membrane device to a raw water tank, in a permeated water extraction part of the reverse osmosis membrane device. A flow rate detector for detecting the flow rate of permeated water is provided, and a flow rate control valve is provided in the circulation pipe, and the opening of the flow rate control valve is controlled based on the detection signal of the flow rate detector to reverse the flow rate. A fresh water producing apparatus characterized in that the permeated water amount of a reverse osmosis membrane device is adjusted to a predetermined amount by adjusting the supply water pressure of the osmotic membrane device. 2. A concentration detector for detecting the salt concentration of raw water is provided in the feed pipe, a shutoff valve is provided between the flow control valve of the circulation pipe and the raw water tank, and the flow control valve of the circulation pipe is provided. And a shut-off valve are connected to a drain pipe with a drain valve interposed therebetween, or a three-way valve having a drain port is attached instead of the shut-off valve, and salt of raw water detected by the concentration detector is attached. The concentrated water is discharged from the discharge pipe by closing the shutoff valve and opening the discharge valve or opening the discharge port of the three-way valve based on a signal from the concentration detector when the concentration becomes a predetermined value or more. Fresh water production equipment. 3. A solar cell module is used as a power source of the fresh water producing apparatus according to claim 1 or 2, and the solar cell module is provided with water collecting means, and the water collecting means and the raw water tank are connected by a water conduit. A fresh water producing apparatus characterized in that the rain water received by the upper surface of the module is connected to the raw water tank via the water collecting means and the water conduit.