JPH10156357A - Desalting system and desalting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a desalting system and desalting device capable of efficiently desalting the sea water, sewage, etc., by making combination use with a pressure air storage tank. SOLUTION: This desalting system 10 consists of the storage tank 11 of a water pressure compensation system which stores the pressure air while compensating the pressure for storage by the water to be pressurized which is sent into the tank and the desalting device 12 which is installed in combination with the storage tank 11. The desalting device 12 consists of a raw water supply vessel 17 formed to attain such a water depth at which the pressure corresponding to the pressure for compressed air storage is obtd. By the static pressure, a reverse osmosis module 31 installed at the water depth at which the water pressure above the reverse osmosis pressure is loaded within the raw water supply vessel 17 and a water lifting pipe 33 and water lifting pump for pumping up the fresh water penetrating into the fresh water collecting pipes of the reverse osmosis module 31 into the atm. A communicating opening 18 for communicating the raw water supply vessel 17 and the storage tank 11 is installed below the installation position of the reverse osmosis module 31.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a desalination method and a desalination apparatus, and more particularly to a desalination method and a desalination apparatus for producing fresh water from seawater or sewage.

[0002]

2. Description of the Related Art For example, seawater is desalinated as a measure to solve water shortage in an area with little rainfall or as an urgent measure when a water supply facility becomes unavailable due to a major earthquake or the like in an urban area. Various techniques for providing drinking water and the like have been proposed.

[0003] As a water treatment technique for purifying and desalinating water, a method using membrane separation is generally known. Among them, a method using water pressure as a driving force is known.
Microfiltration for separating flocs and fine particles such as suspended substances and bacteria, ultrafiltration for separating high molecular substances such as polysaccharides and proteins, reverse osmosis for separating dissolved ions such as chloride ions Can be mentioned.

[0004] According to the reverse osmosis method, for example, by applying a high pressure equal to or higher than the osmotic pressure from the solution side to the semipermeable membrane having the property of preventing the passage of solute, only fresh water is applied to the semipermeable membrane. The desalination of the solution is carried out while passing through the filter. In order to achieve practical use on an industrial scale, it is performed using a reverse osmosis module incorporating such a reverse osmosis membrane.

That is, in this reverse osmosis module, for example, a solution such as seawater is supplied to the outer periphery of the reverse osmosis module under a high water pressure, and the fresh water that has passed through the reverse osmosis membrane is collected by an internal water collecting pipe by this pressure. This is an apparatus that can extract this.

[0006] Such a reverse osmosis membrane requires a high water pressure of, for example, about 30 kgf / cm ² or more in order to exert its function. Therefore, such a high pressure is applied to the reverse osmosis module. Requires a large-scale pressure vessel and consumes a great deal of energy as a power to keep applying such a high pressure. A desalination apparatus and a desalination method capable of easily obtaining a reverse osmotic pressure have been developed by the inventor of the present invention (see “Desalination method and desalination” filed on the same date as the present application by the present applicant. Equipment ”).

On the other hand, in recent years, various underground tanks have been developed as facilities for storing surplus electric power such as midnight electric power as compressed air or the like and other facilities for storing high-pressure gas. That is, according to the underground tank for storing such compressed air, by providing the underground tank in the deep underground, the withstand pressure for resisting the internal pressure of the compressed air supplied by the air pipe and stored inside, Compensated by earth pressure or groundwater pressure applied to the underground tank from the surrounding ground,
Thereby, the tensile stress generated in the underground tank can be reduced, the structure of the underground tank can be simplified, and the underground space can be effectively used.

As an underground tank for storing such compressed air, a so-called underwater storage tank of a so-called hydraulic pressure compensation system is known. This water pressure compensated underground storage tank
For example, as is known as a CAES (Compressed Air Energy Storage) tank, an upper pond composed of a reservoir, a lake, a marsh, a river, an underground river, and the like provided above the underground tank communicates with a lower space of the underground tank by a water pipe. At the same time, by filling the water supply pipe with pressurized water due to the head difference between the water level in the underground tank and the water level in the upper pond, the pressure caused by this head difference causes the compressed air storage space in the underground tank to pass through the water surface. (See Japanese Patent Application Laid-Open No. Hei 7-18).
9273, JP-A-7-330079, etc.).

[0009]

According to the desalination apparatus and the desalination method described above, the reverse osmosis module can be installed at a predetermined depth in the sea from, for example, the sea surface to achieve desalination. For example, a dedicated water tank can be formed in the ground, and a reverse osmosis module can be installed inside the tank to perform desalination work.However, such a water tank can significantly affect the weather and waves. It is possible to work in a quiet environment without receiving it, and it is possible to easily install auxiliary equipment such as a device for pumping and treating desalinated water and a compressor for sending air on the ground. On the other hand, there is an advantage, however, that a large amount of energy is required to pump and treat wastewater having a high specific gravity after desalinating raw water.

Further, according to the desalination apparatus and the pneumatic storage tank of the hydraulic pressure compensation type, both of the high pressure are required to obtain the osmotic pressure for desalination or to apply the pressure for pneumatic storage. Since pressurized water is used, it is convenient if it is possible to efficiently perform desalination and compressed air storage by using these together.

Accordingly, the present invention has been made in view of such conventional problems, and a desalination system capable of efficiently desalinating seawater, sewage, and the like by coexisting with a pneumatic storage tank. And a desalination method.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to achieve such an object, and the gist of the invention is to compensate for the pressure for storage while compensating the pressure for storage by pressurized water sent into a tank. A desalination system comprising a storage tank of a hydraulic pressure compensation type for storage and a desalination device provided in parallel with the storage tank, wherein the desalination device has a static pressure corresponding to the pressure for compressed air storage. A raw water supply tank formed to have a water depth obtained by water pressure, a reverse osmosis module installed at a depth where a water pressure equal to or higher than a reverse osmotic pressure is loaded inside the raw water supply tank, Pumping means for pumping fresh water permeated into the freshwater collecting pipe into the atmosphere, and communicating means for communicating the raw water supply tank and the storage tank below the installation position of the reverse osmosis module. In desalination system according to claim.

[0013] In the above description, the reverse osmosis module cannot be put to practical use with the reverse osmosis membrane itself, and has a shape that can be put to practical use on an industrial scale. Equipment: flat membrane type (plate / frame) module, glue type (spiral type) module, hollow fiber type (hollow fiber type)
Modules and the like can be used.

[0014] Of these reverse osmosis modules, the glue-wound module has the highest membrane filling amount per volume and is the most practical one. For example, two flat modules with the active layer on the outside are used. The membrane is adhered in the shape of an envelope, a spacer serving as a permeated water flow path material is inserted inside the envelope, and one end of the envelope is opened and connected to a water collecting pipe having many holes, and the raw water flow path is held and disturbed. The mesh spacer serving as a flow-promoting action is sandwiched between a plurality of envelope-shaped membranes (leaves), and is wound around the water collecting pipe in the form of a roll to form an element.

As the reverse osmosis membrane, a sponge-like membrane having a dense active layer having a thickness of 0.1 to 1 μm and exhibiting a large number of pores having a thickness of several μm, such as a cellulose acetate membrane, is used. Use of an asymmetric membrane composed of a support layer or a composite membrane composed of a support layer composed of a polysulfone membrane and a surface active layer composed of a polyamide-based material formed by a technique such as interfacial polymerization, cross-linking treatment, or plasma polymerization. Can be.

Further, in the desalination system according to the present invention, the desalination apparatus may be provided with an atmospheric pressure pipe that communicates the freshwater collecting pipe with the atmosphere and supplies the atmosphere to the freshwater collecting pipe. preferable.

Further, in the desalination system of the present invention, a storage tank is provided above the storage tank for storing discharged water pushed out of the storage tank when storing compressed air.
In order to maintain a predetermined head difference (head difference) in the storage tank by maintaining the water level in the storage tank below the level of raw water sent to the raw water supply tank by discharging the discharged water. Drainage means may be provided.

Still further, in the desalination system of the present invention, the upper end of the raw water supply tank is communicated with a pretreatment water tank, and the raw water treated by the pretreatment membrane in the pretreatment water tank is supplied to the raw water supply tank. You may make it supply to.

On the other hand, another gist of the present invention is to provide a raw water supply tank provided in addition to a water pressure compensation type storage tank which stores compressed air while compensating for a storage pressure by pressurized water sent into the tank. Inside, a reverse osmosis module is installed at a depth where a water pressure equal to or higher than the reverse osmosis pressure is applied, and fresh water that has permeated the freshwater collecting pipe of the reverse osmosis module is pumped into the atmosphere, and the internal pressure of the freshwater collecting pipe and the reverse pressure are set. A pressure difference is generated between the water pressure around the osmosis module and the pressure difference as a reverse osmosis pressure, while desalinating seawater and sewage, and a wastewater having a large specific gravity after passing through the reverse osmosis module. From the communicating means that communicates the raw water supply tank and the storage tank below the reverse osmosis module, flows into the storage tank as pressurized water, and flows the wastewater into the storage tank. In desalination method characterized by discharging upwardly as the water discharged when supplying storing gas.

According to the desalination system of the present invention, the reverse osmosis module is installed at a predetermined water depth in the raw water supply tank, and the fresh water penetrating the fresh water collecting pipe is pumped into the atmosphere. For example, due to the hydrostatic pressure of raw water from the surroundings, the internal pressure of the freshwater collecting pipe sandwiching the reverse osmosis membrane,
The pressure difference equal to or higher than the reverse osmotic pressure always occurs in a natural state, and the fresh water obtained from the raw water through the reverse osmosis membrane as the reverse osmotic pressure is collected in the freshwater collecting pipe. Will be pumped to the ground.

On the other hand, the concentrated raw water that has passed through the reverse osmosis module while partly penetrating the freshwater collecting pipe, sinks below the raw water supply tank as wastewater having a large specific gravity, and has a communication opening and a communication hole. It flows into the storage tank as pressurized water via communication means such as a pipe and is stored.

Then, the wastewater stored in the storage tank in this way, due to the head difference between the level of the raw water taken into the raw water supply tank and the level of the raw water,
In addition to functioning as pressurized water that compensates for the pressure for compressed air storage, when the compressed air is fed into and stored in this storage tank, the pressure of the compressed air that is pushed in depends on the volume of compressed air stored. As a result, it is pushed upward from the storage tank and discharged.

Further, if the desalination apparatus is provided with an atmospheric pressure pipe for communicating the fresh water collecting pipe of the reverse osmosis module with the atmosphere and supplying the atmosphere to the fresh water collecting pipe, the internal pressure of the fresh water collecting pipe becomes atmospheric pressure. This makes it possible to desalinate seawater and sewage in a stable state while maintaining a constant pressure difference required for reverse osmosis.

Further, a drainage storage tank is provided above the storage tank, and the drainage means drains this drainage appropriately to maintain the water level in the storage tank below the level of the raw water sent to the raw water supply tank. By doing so, the wastewater that has passed through the reverse osmosis module can easily flow into the storage tank through the communication opening or the like due to the head difference between them.

Furthermore, by connecting the upper end of the raw water supply tank to the pretreatment tank and supplying the raw water treated by the pretreatment membrane to the raw water supply tank, impurities are removed and the water quality is stabilized. Raw water can be supplied to the reverse osmosis module, thereby facilitating maintenance and management of the reverse osmosis module and extending the life of the reverse osmosis membrane.

On the other hand, according to the desalination method of the present invention, in the raw water supply tank, the raw water that has passed through the reverse osmosis module installed at the depth where the water pressure equal to or higher than the reverse osmotic pressure is applied, has a higher specific gravity than the raw water before passing. As a large waste water, it sinks further downward, and flows into the storage tank through communication means such as a communication opening or a communication pipe. The wastewater that has flowed into the storage tank functions directly as pressurized water for pressurized storage due to the head difference between the raw water level supplied to the raw water supply tank and the compressed air stored in the storage tank. In this case, the air is pushed upward by the compressed air and is discharged from the storage tank.

That is, according to the present invention, a storage tank of a hydraulic pressure compensation type which requires a predetermined pressure utilizing hydrostatic pressure and a desalination apparatus coexist, and these functions are combined to provide an efficient seawater. And desalination of wastewater and the like can be easily achieved.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention, ie, embodiments, will be described below in detail with reference to the accompanying drawings. Desalination system 10 according to this embodiment
Is a system for desalination of seawater in which a compressed air storage tank 11 and a desalination device 12 coexist. As shown in FIGS. 1 and 2, mainly a pressurized water sent into the tank. The storage tank 11 is configured by a water pressure compensation type storage tank 11 that stores compressed air while compensating for a storage pressure, and a desalination device 12 provided on a side wall 13 of the storage tank 11.

Here, the storage tank 11 is formed in the lower half portion of a cylindrical body 14 having a double-structured side wall 13 constructed from the ground to a depth of about 300 m below the ground, for example. It functions as a CAES tank for storing surplus electric power such as electric power as compressed air, that is, a tank for storing compressed air in a water pressure compensation system.

The storage tank 11 has a cylindrical shape 1
A floor slab 15 for closing the lower end of the inner wall 4 and an inner wall 1 of the side wall 13
9 and a ceiling slab 16 formed at a depth of about 150 m underground
And a storage space surrounded by
A communication opening 18 for inflowing waste water from a raw water supply tank 17 formed between an inner wall 19 and an outer wall 20 constituting the side wall portion 13 is formed at the lower end portion as communication means. At the same time, an air supply pipe 21 for compressed air that opens to the upper end of the storage tank 11 and extends to the ground so as to penetrate the ceiling plate 16 and extends to the ground, and the storage tank 11 that opens to the lower end of the storage tank 11 and A stored water discharge pipe 23 that communicates with the upper discharged water storage tank 22 is provided.

Therefore, for example, the storage tank 11
From the state where wastewater is filled and stored in the storage tank 1, a compressor or the like is operated using late-night electric power or the like to generate compressed air, and this is used as compressed air to store the storage tank 1 through the air supply pipe 21.
1 into the storage tank 1 due to its high pressure.
Inside, the compressed air is gradually stored while pushing up the internal waste water to a drainage storage tank 22, and the compressed air contains the level of the waste water remaining in the storage tank 11 and the raw water supply tank 17. Hydrostatic pressure due to the head difference between the raw water level supplied to the
With the balance between the pressure of the compressed air and the hydrostatic pressure maintained in this way, the compressed air is stored in the storage tank 11 by a so-called hydraulic compensation method (see FIG. 3).

The cylindrical body 14 provided with the storage tank 11 is constructed by a method described in, for example, Japanese Patent Application Laid-Open No. 7-252854, that is, for holding a wall surface in a vertical hole excavated and formed in the ground. Fill the filling liquid, insert a mold membrane consisting of a double-layered bag into this vertical hole,
The method of constructing a concrete underground tank by placing concrete in this double-layered mold membrane while sinking it to the bottom of the vertical hole, while improving it, It can be easily constructed and installed to a depth of about 300m below the ground.

The gap between the inner wall surface of the vertical hole in which the cylindrical body 14 is installed and the cylindrical body 14 is, for example, disclosed in
As shown in No. 9273, the muddy water 37 is filled,
The pressure of the heavy muddy water can stabilize the inner wall surface of the cylindrical body 14 and the vertical hole.

On the other hand, the desalination apparatus 12 constituting the desalination system 10 together with the compressed air storage tank 11 has a cross section formed between the inner wall 19 and the outer wall 20 of the double side wall 13 of the cylindrical body 14. A raw water supply tank 17 having an annular shape and a depth reaching the lower end portion of the cylindrical body 14, and 24 raw water supply tanks 17 provided in the inside of the raw water supply tank 17 having an annular cross section along the circumferential direction thereof. And a desalination unit 23.

The upper end of the raw water supply tank 17 communicates with a pretreatment tank 26 via a communication pipe 25, and the raw sea water introduced from a sea water intake pump or a sea water intake through a flow path 29 is introduced. Is supplied to the raw water supply tank 17 after being pretreated by passing through a pretreatment membrane 27 such as an ultrafiltration membrane provided in a pretreatment tank 26.

Each desalination unit 23 is shown in FIG. 4 which is an enlarged view thereof, and FIGS. 5, 6 and 7 which are AA section, BB section and CC section of FIG. 4, respectively. As shown, the reverse osmosis membrane elements 31 as a total of 12 reverse osmosis modules arranged radially in four rows and three stages, respectively, and the reverse osmosis membrane elements 3 arranged in these four rows
1, a pumping pipe 33 extending vertically from the water depth where the reverse osmosis membrane element 31 is installed to the ground, and below the lowermost reverse osmosis membrane element 31, A production water tank 32 for accumulating fresh water permeated through the membrane element 31 is provided, and the pumping pipe 33 communicates with the production water tank 32 and extends upward. A water pump 34 is provided so as to be inserted and mounted at a lower end portion of 33.
The pump 34 and the pump 33 constitute a pumping means for pumping fresh water into the atmosphere.

Here, each reverse osmosis membrane element 31 is, for example, a well-known winding type, with a reverse osmosis membrane, a permeated water channel material, and a fresh water collecting pipe 35 having a large number of holes as a center. An element member formed by winding a plurality of envelope-shaped membranes (leaves) sandwiching a raw water flow path material or the like in a rolled form, and a fresh water collecting pipe 35 of a three-stage reverse osmosis membrane element 31 in each row. Communicates in the up-down direction, the lower end thereof opens to the ceiling wall of the production water tank 32, and the upper end communicates with the atmospheric pressure pipe 36 which is disposed and extended along the pumping pipe 33 and opens to the atmosphere. Then, the atmosphere, that is, the air, can be supplied from the atmosphere to the freshwater collecting pipe 35.

Each of the reverse osmosis membrane elements 31 is supported by a pumping pipe 33 via a metal pedestal or the like with a wedge member made of, for example, hard rubber interposed at a vertical interval. Further, each reverse osmosis membrane element 31 has 3
By being arranged at the lower end of the raw water supply tank 17 having a water depth of about 00 m, the hydrostatic pressure required for reverse osmosis can be easily obtained.

On the other hand, the pumping pipe 33 is a pipe body which is formed by casting concrete in a gap between a steel pipe or a thin steel pipe having a double structure, for example, extending upward from the ceiling wall of the production water tank 32, and in the latter case. In addition, a reinforcing material such as a reinforcing steel bar or a PC steel wire is appropriately disposed in the concrete, and the structure is such that when the fresh water is pumped from the production water tank 32, the structure can sufficiently withstand the water pressure applied from the outer periphery. A plurality of piano wires are extended in the axial direction so that prestress can be applied also in the axial direction.

While the desalination unit 23 is suspended in the raw water in the raw water supply tank 17 from the ground via these piano wires and steel pipes, the pumping pipes 33 are sequentially driven upward by welding or casting concrete. By successively forming, the desalination unit 23 can be easily settled and installed at the bottom of the raw water supply tank 17.

On the other hand, a production water tank 32 located below the reverse osmosis membrane element 31 for collecting fresh water is made of, for example, precast concrete covered with a steel plate, and the desalination unit 23 is installed at a predetermined water depth. Even if the internal pressure is maintained at atmospheric pressure after that, it has sufficient strength to withstand the hydrostatic pressure applied from the outer periphery, and inside this,
A pump 34 is provided.
, The fresh water produced to the atmosphere can be pumped up to the atmosphere through the pumping pipe 33 whose upper end is inserted and mounted.

Further, the desalination unit 23 of this embodiment
According to the above, for example, a first air lift pipe 41 and a second air lift pipe 42, which are pressure-resistant tubes for supplying air for air lift using a compressor, are provided.

Here, the first air lift pipe 41 is provided so as to extend along the water pumping pipe 33, and the nozzle at the tip of the first air lift pipe 41 extends inward of the water pumping pipe 33 halfway above the reverse osmosis membrane element 31. By blowing air from the tip nozzle, the fresh water inside the pumping pipe 33 can be pushed up to the atmosphere with the buoyancy of the blown air, whereby the fresh water is pumped up by the water pump 34. Work can be complemented.

The second air lift pipe 42 is extended along the pumping pipe 33 and then branched, and its leading end opening is formed at the outer periphery of the reverse osmosis membrane element 31 below the reverse osmosis membrane element 31. And the inner wall 19 and the outer wall 20 of the raw water supply tank 17 are arranged at a space between the inner wall 19 and the outer wall 20. The air is blown out from the space and the outer periphery of the reverse osmosis membrane element 31 by the floating action of the blown air. The surface can be cleaned.

Further, the raw water that has passed through each reverse osmosis membrane element 31 flows down the waste water pipe 43 and is discharged to the raw water supply tank 17 below the reverse osmosis membrane element 31.

According to the desalination system 10 of the present embodiment having the above-described configuration, desalination of seawater is performed as follows.

That is, the raw seawater introduced from a predetermined sea area through the intake channel 29 is
And the head difference between the raw seawater level in the pretreatment tank 26 and the raw seawater level in the pretreatment tank 26, the pretreatment tank 26 passes through the pretreatment membrane 27 installed in the pretreatment tank 26.
The pretreated raw water is supplied to the raw water supply tank 17 through the connecting pipe 25, and the raw water is kept constantly filled in the raw water supply tank 17 (FIG. 1). reference).

Then, from this state, by driving the pump 37 of each desalination unit 23 to pump the water inside each production water tank 32 to the atmosphere, the water inside the production water tank 32 is removed. Eventually, the inside of the atmospheric pressure pipe 36 and the freshwater collecting pipe 35 will be placed under the atmospheric pressure, whereby the freshwater collecting pipe 35 located at the center of the reverse osmosis membrane element 31 and the reverse osmosis where the raw water comes into contact. Membrane element 3
1 between the reverse osmosis membrane element 31
The pressure difference corresponding to the hydrostatic pressure corresponding to the water depth at which is installed is always generated in a natural state (see FIG. 4).

Therefore, using this pressure difference as the reverse osmotic pressure, fresh water is infiltrated and produced from the surrounding raw water into the fresh water collecting pipe 35, and this produced water is accumulated in the production water tank 32, and is pumped by the water pump 33. Will be pumped to the ground via.

By adjusting the amount of water pumped by the water pump 34, the amount of fresh water permeated from the reverse osmosis membrane element 31 and the amount of water pumped by the water pump 34 are kept in an equilibrium state. Seawater desalination will be performed.

On the other hand, the raw water that has passed through the reverse osmosis membrane element 31 while partly penetrating the freshwater collecting pipe 35 is passed through the waste water pipe 43 through the waste water pipe 43 as concentrated wastewater having a high specific gravity. The communication opening 1 formed at the lower end of the inner wall 19 as it sinks below the supply tank 17.
The wastewater flowing into the storage tank 11 from the storage tank 8 and stored in the storage tank 11 in this manner is stored in the storage tank 11 by a head difference between the raw water level in the pretreatment tank 26 and the wastewater. It will function as pressurized water that compensates for the pressure for pneumatic storage.

The wastewater flows into the storage tank 11 in a pressure reducing step in which the compressed air stored in the storage tank 11 is taken out and consumed as motive energy for gas turbine power generation or the like. The water flows particularly smoothly with the rise of the water level in the inside, but also in the compressed air storing step in which the compressed air fed while pushing the wastewater is stored in the storage tank 11 (FIG. 3).
), A head difference of a predetermined size is maintained between the level of the stored water in the discharged water storage tank 22 and the level of the raw water in the pretreatment tank 26, as described later.
The wastewater easily flows into the storage tank 11 due to the head difference.

Then, the desalination system 10 of this embodiment
According to the above, the wastewater that has passed through the reverse osmosis membrane element 31 and stored in the storage tank 11 as described above is easily discharged to the ground or the surrounding sea area.

That is, the stored compressed air is consumed, the pressure in the storage tank 11 is reduced, and the level of the wastewater flowing from the raw water supply tank 17 and stored is at the highest level. If the compressed air generated by using the surplus electric power is pressure-fed into the storage tank 11 through the air supply pipe 21, the wastewater inside the storage tank 11 is pushed up to the discharge water storage tank 22 by the high pressure. The pressure is gradually stored while discharging.

Therefore, according to this embodiment, CAE
The waste water is easily pushed up and discharged into the discharge water storage tank 22 without requiring any special power, which is incorporated in the normal pressure storage process when storing the compressed air in the S tank. become.

The wastewater stored in the drainage storage tank 22 is drained by driving a drainage pump or the like installed in the drainage storage tank 22 as drainage means.
Can be easily discharged via the drainage pump, and by adjusting the discharge amount by such a drainage pump or the like, the water level in the discharge water storage tank 22 becomes lower than the water level of the raw water in the pretreatment tank 26. It can be easily maintained.

When the level of the surrounding seawater is lower than the level of the raw water in the pretreatment tank 26, for example, a drainage flow path communicating the discharged water storage tank 22 with the surrounding sea area is provided. The wastewater may be discharged by a flow-down method.

Also, as described above, the discharged water storage tank 22
Since the wastewater stored in the seawater is concentrated seawater after desalination treatment, it is possible to obtain uranium, lithium, and the like as by-products of desalination by mixing, for example, lithium adsorption spheres. .

In this way, the desalination system 10 according to this embodiment, in which the compressed air storage tank 11 and the desalination device 12 each requiring a predetermined pressure using the hydrostatic pressure coexist, is provided. According to this, by combining these functions, efficient desalination of seawater can be easily performed.

That is, the motive energy for pumping fresh water from the production water tank 32 into the atmosphere by the pump 37 is the same as that when fresh water is obtained by reverse osmosis by applying a pressure similar to the hydrostatic pressure at the water depth in the atmosphere. It is considered that much less energy is required than the required power energy (if it is considered to produce one-third of the amount of freshwater, the power to pump freshwater from the sea will be It is considered that only one-third of the power for pressurizing is required.) Also, in order to pump wastewater stored in the compressed air storage tank 11 through the reverse osmosis membrane element 31 into the discharge water storage tank 22. Since the power is built into the normal pneumatic storage process and a dedicated power is not required, the wastewater is discharged from the discharged water storage tank 22 to the surrounding sea area. Even when considering the power of the drainage pump, as a whole, it is considered that requires only conventional 40% to 50% of the power.

The present invention is not limited to the embodiment of the above embodiment, but may be variously modified and adopted within the scope of the constitution described in each claim.

For example, the desalination apparatus does not necessarily need to be incorporated in the side wall of the pneumatic storage tank and provided integrally, and the pneumatic storage tank and the desalination apparatus can be formed as separate structures. Can be used not only for desalination of seawater but also for desalination of sewage.

Further, the pumping means for pumping the produced fresh water can be used without being limited to a pump. In particular, in the present invention, since the compressed air is stored in the storage tank, It is considered that it is particularly effective to configure the pumping means by an air lift.

[0064]

As described above in detail, according to the desalination system and the desalination method of the present invention, the hydrostatic pressure can be reduced only by pumping fresh water that has penetrated from a desalination apparatus installed at a predetermined depth. Coexist with the desalination equipment and the water pressure compensation type compressed air storage tank that can easily desalinate seawater and sewage while using it, and use both high-pressure and pressurized water. Accordingly, desalination of seawater, sewage, and the like can be efficiently achieved by combining these functions.

If a treatment water tank is provided to desalinate raw water after pre-treatment, impurities can be removed and raw water with stable water quality can be supplied to the reverse osmosis module. In addition, maintenance and management of the reverse osmosis module are facilitated, and the life of the reverse osmosis membrane can be extended.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a desalination system according to an embodiment of the present invention.

FIG. 2 is a schematic plan view of the desalination system according to the embodiment of the present invention, as viewed from above and illustrating the configuration of FIG.

FIG. 3 is a cross-sectional view showing an example of a situation where the most compressed air is stored in the desalination system of FIG.

FIG. 4 is a cross-sectional view illustrating a configuration of a desalination apparatus according to one embodiment of the present invention.

FIG. 5 is a cross-sectional view taken along the line AA of FIG. 4 for explaining the configuration of the desalination apparatus according to one embodiment of the present invention.

FIG. 6 is a cross-sectional view taken along the line BB of FIG. 4 for explaining the configuration of the desalination apparatus according to one embodiment of the present invention.

FIG. 7 is a cross-sectional view taken along the line CC of FIG. 4 for explaining the configuration of the desalination apparatus according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Desalination system 11 Compressed air storage tank 12 Desalination device 13 Side wall part 14 Cylindrical body 17 Raw water supply tank 18 Communication opening (communication means) 21 Air supply pipe 22 Drainage water storage tank 23 Storage water removal pipe 26 Pretreatment tank 27 Pretreatment membrane Reference Signs List 30 Desalination unit 31 Reverse osmosis membrane element (reverse osmosis module) 32 Production tank 33 Pumping pipe (pumping means) 34 Pumping pump (pumping means) 35 Freshwater collecting pipe 36 Atmospheric pressure pipe 44 Drainage pipe

 ──────────────────────────────────────────────────続 き Continued on the front page (71) Applicant 000005902 Mitsui Engineering & Shipbuilding Co., Ltd. 5-6-1 Tsukiji, Chuo-ku, Tokyo (72) Inventor Masao Hayashi 131-1 Wakamatsu, Abiko-shi, Chiba (72) Inventor Keiichi Ota (72) Inventor Kiyojun Koyamauchi 11-1 Haneda Asahimachi, Ota-ku, Tokyo Ebara Manufacturing Co., Ltd. (72) Inventor Atsushi Motoyama 181-1 Komagaki, Nagareyama-shi, Chiba Mitsui Construction (72) Inventor Takuhisa Yamaguchi 5-6-4 Tsukiji, Chuo-ku, Tokyo Inside Mitsui Engineering & Shipbuilding Co., Ltd.

Claims (5)

[Claims] 1. A freshwater comprising a water pressure compensation type storage tank for storing compressed air while compensating a pressure for storage by pressurized water sent into the tank, and a desalination device provided in parallel with the storage tank. A desalination apparatus, wherein the desalination apparatus has a raw water supply tank formed so that a pressure corresponding to the pressure for storing the compressed air has a water depth obtained by hydrostatic pressure, and an inside of the raw water supply tank has a reverse flow. A reverse osmosis module installed at a depth to which a water pressure equal to or higher than the osmotic pressure is applied, and a pumping means for pumping fresh water permeated into a fresh water collecting pipe of the reverse osmosis module into the atmosphere, and the raw water supply tank and the storage A desalination system, comprising a communication means for communicating with a tank below the installation position of the reverse osmosis module. 2. The fresh water according to claim 1, wherein the desalination apparatus further includes an atmospheric pressure pipe that connects the fresh water collecting pipe to the atmosphere and supplies the atmosphere to the fresh water collecting pipe. System. 3. A storage tank is provided above the storage tank for storing discharge water pushed out from the storage tank when storing compressed air, and the discharge tank discharges the discharge water to the storage tank. The drainage means for maintaining the water level in the storage tank below the level of the raw water sent to the raw water supply tank and maintaining a predetermined head difference is provided. Desalination system. 4. The raw water supply tank communicates with an upper end of the raw water supply tank with a pretreatment water tank, and the raw water treated by the pretreatment membrane in the pretreatment water tank is supplied to the raw water supply tank. The desalination system according to any one of claims 1 to 3. 5. A raw water supply tank provided in parallel with a water pressure compensation type storage tank for storing compressed air while compensating for a pressure for storage by pressurized water sent into the tank and having a reverse osmotic pressure or higher. A reverse osmosis module is installed at the depth where the water pressure is applied, and fresh water that has permeated the freshwater collection pipe of the reverse osmosis module is pumped into the atmosphere, and the internal pressure of the freshwater collection pipe and the water pressure around the reverse osmosis module are adjusted. A pressure difference is generated between the two, and the pressure difference is used as a reverse osmosis pressure to achieve desalination of seawater and sewage, and wastewater having a large specific gravity after passing through the reverse osmosis module is provided below the reverse osmosis module. From the communicating means that communicates the raw water supply tank and the storage tank, the raw water is introduced into the storage tank as pressurized water, and the inflowing wastewater is discharged to supply and store compressed air in the storage tank. A desalination method characterized by discharging the water upward.