JP7068116B2 - Draw solution used in water treatment systems and water treatment systems - Google Patents

Description

Embodiments of the present invention relate to water treatment systems and working media.

When the solution with low solute concentration and the solution with high solute concentration are separated by the osmotic membrane, the solvent of the low concentration solution permeates the osmotic membrane and moves to the solution side with high concentration. There are known desalination systems that perform desalination such as seawater desalination and osmotic power generation systems that generate electricity by turning a turbine by utilizing this phenomenon of solvent movement. In addition, a concentration system for concentrating foods and sludge using this is also known. At this time, a working medium (draw solution) is used on the side with a high concentration, and various ones have been proposed so far.

Salt is generally used as the solute of the draw solution. Organic salts are also used as solutes in draw solutions. However, the water permeation flux of the organic salt draw solution is inferior to that of the salt draw solution.

A draw solution in which two or more kinds of solutes are mixed has been proposed. A synergistic effect is observed with a mixture of multiple inorganic salts, but in the case of inorganic salts and saccharose, the flux passing through the osmotic membrane may be reduced due to the adverse effect.

Special Table 2013-518718 Gazette

An object to be solved by the present invention is to provide a water treatment system and a working medium capable of separating water at low cost.

The water treatment system of the embodiment is
An osmotic pressure generator with a first treatment vessel having an osmotic membrane that separates a first chamber containing water to be treated and a second chamber containing an osmotic solution that induces osmotic pressure, and carbon dioxide is released from the draw solution . It has a carbon dioxide releasing means for causing carbon dioxide to be released, a phase separating means for separating the phase-separated draw solution , and a concentrator having a carbon dioxide introducing means for absorbing carbon dioxide in the draw solution. The draw solution contains an amine compound. The amine compound is a compound represented by the formula (1) or (2). R ¹ in the formula (1) is a linear alkyl chain having 1 to 3 carbon atoms. R ² in the formula (2) is a linear alkyl chain having 1 to 3 carbon atoms. Any one of R ³ to R ⁶ in the formula (2) is a methyl group or an ethyl group.

The schematic diagram of the water treatment system which concerns on 1st Embodiment. Chemical formula of the solute according to the embodiment. The schematic diagram of the desalting system which concerns on 2nd Embodiment. The schematic diagram of the osmotic power generation system which concerns on 3rd Embodiment. Chemical formula of the solute according to the comparative example.

Hereinafter, the water treatment system of the embodiment and the work medium used for the water treatment system will be described.
(First Embodiment)
FIG. 1 is a schematic diagram of a water treatment system according to the first embodiment. The water treatment system 100 includes an osmotic pressure generator 1 having a first treatment container 11 having a osmotic film 12 for partitioning a first chamber 13 for accommodating the water to be treated A and a second chamber 14 for accommodating the work medium B. In the concentrator 2, the working medium B induces osmotic pressure in the osmotic pressure generator 1, and the concentrator 2 absorbs carbon dioxide gas into the working medium B and releases carbon dioxide from the working medium B.

According to such a water treatment system 100, in the water to be treated A in the first chamber 13 due to the osmotic pressure difference generated between the water to be treated A in the first chamber 13 and the working medium B in the second chamber 14. Water C permeates through the osmotic film 12 and moves to the working medium B in the second chamber 14.

The working medium B tends to induce osmotic pressure by absorbing carbon dioxide gas. Then, the working medium B is separated from water by releasing carbon dioxide gas, and the working medium B is concentrated. For concentration of the work medium B, solid-liquid separation or liquid-liquid separation is performed. By allowing the concentrated work medium B to absorb carbon dioxide gas, it becomes possible to make the medium easily induces osmotic pressure again. Therefore, in the embodiment, water treatment is performed at low cost.

By using the working medium B of the embodiment, the water C in the water to be treated A in the first chamber 13 is permeated through the osmosis membrane with a large permeation flux and moved to the working medium B in the second chamber 14. The water treatment system of the embodiment is preferable in that The working medium B of the embodiment is used for a water treatment system and a water treatment system that can be operated at low cost.

The first processing container 11 is divided into a first chamber 13 and a second chamber 14 by a osmosis membrane 12. The first treatment container 11 is a resin or metal container in which the water to be treated A is housed in the first chamber 13 and the work medium B is housed in the second chamber 14.

The osmosis membrane 12 may be, for example, a forward osmosis membrane (FO membrane) or a reverse osmosis membrane (RO membrane). A preferred osmosis membrane is a FO membrane.

As the osmosis membrane 12, for example, a cellulose acetate membrane, a polyamide membrane, or the like can be used. The osmosis membrane preferably has a thickness of 45 μm or more and 250 μm or less.

The first chamber 13 is a region in the first treatment container 11 for accommodating the water to be treated A, and the compartments are separated by the osmosis membrane 12. The first chamber 13 may be provided with an introduction / discharge path (not shown) into which the water to be treated A is introduced / discharged.

The water to be treated A is a liquid having a lower solute concentration than the working medium. Examples of the water to be treated A include salt water (seawater and the like), lake water, river water, swamp water, domestic wastewater, industrial wastewater, or a mixture thereof. When the water to be treated A is salt water, the salt (sodium chloride) concentration of the salt water may be, for example, 0.05% to 8%. The water to be treated A contains salts such as sodium chloride, magnesium chloride, magnesium sulfate, calcium sulfate, and potassium chloride and floating substances, and substances other than water are concentrated.

The second chamber 14 is a region in the first processing container 11 that houses the work medium B, and is separated by a osmosis membrane 12.

The concentrator 2 includes a carbon dioxide emitting means for releasing carbon dioxide from the working medium B, a phase separating means for separating the phase-separated working medium B, and a carbon dioxide introducing means for causing the working medium B to absorb carbon dioxide. Further, the concentrator 2 may further include a storage means for storing the concentrated work medium B. As the phase separation means, a three-phase separation type centrifuge or the like can be used. As the carbon dioxide introducing means, a carbon dioxide bubbling device or the like may be used, or dry ice (solid carbon dioxide) may be charged into the work medium B. As the carbon dioxide emitting means, a heating device, a bubbling device for an inert gas, or the like can be used. From the viewpoint of energy cost, it is preferable to use a heat exchanger that utilizes waste heat as the heating device. Further, as the carbon dioxide used in the carbon dioxide introducing means, the carbon dioxide released by the carbon dioxide releasing means may be used, or the gas obtained by purifying carbon dioxide such as in the exhaust gas of a power plant using fossil fuel. May be used.

The working medium B of the first embodiment contains an amine compound which becomes a liquid whose characteristics change depending on the concentration of carbon dioxide in the solution. In the working medium B of the embodiment, the valence of the amine compound increases as the carbon dioxide concentration increases, and osmotic pressure is induced. Then, when the carbon dioxide concentration of the working medium B is lowered, the amine compound is separated from water, so that the working medium B can be concentrated. Then, by increasing the carbon dioxide concentration of the working medium B again, the medium becomes an excellent medium for inducing osmotic pressure.

Since the process of changing the carbon dioxide concentration in the work medium B and the separation from water have low energy, water treatment operation at low cost becomes possible.

The water produced by the concentration of the working medium B may contain low concentrations of amine compounds. This is the loss of the amine compound. Further, if the water treatment is desalination, it becomes impurities in water generated by the concentration of the work medium B. Therefore, when the water produced by the concentration of the working medium B contains a low concentration amine compound, the water generated by the concentration of the working medium B is treated with a reverse osmosis membrane separator to concentrate the liquid containing the amine compound. , Can be returned to the working medium B and the generated water can be obtained. In the operation with the reverse osmosis membrane separator, the concentration of the amine compound in the liquid to be treated is low, so that the water treatment can be performed with lower energy than the concentration treatment with the reverse osmosis membrane separator alone. In the concentrator 2, there is a large difference in cost between the case of performing reverse osmosis membrane separation and the case of performing the concentration of the embodiment, and the water treatment of the embodiment is excellent in terms of cost.

The amine compound of the embodiment changes its solubility in water depending on the concentration of carbon dioxide in the medium. Utilizing this characteristic, the work medium B is concentrated. As a method for causing the work medium B to absorb carbon dioxide, for example, a gas containing carbon dioxide may be blown into the work medium B. At this time, if the temperature is too high, carbon dioxide is released, so carbon dioxide may be blown into the work medium B at 80 ° C. or lower. Further, in order to release carbon dioxide in the work medium B, an inert gas such as nitrogen gas may be blown into the work medium B. At this time, by heating to a temperature lower than the boiling point of the working medium B, the carbon dioxide emission rate is increased. The carbon dioxide concentration in the working medium B when introduced into the osmotic pressure generator 1 is 1 or more and 3 or less when the molar concentration of the working medium B is 1. The introduced carbon dioxide concentration can be confirmed by measuring the 13C quantitative NMR of the working medium B. For the measurement, a double tube capable of separating the deuterated solvent and the working medium B is used. From the integrated value ratio of the obtained peaks, the molar concentration ratio of the amine compound contained in the working medium B and the amount of carbon dioxide introduced can be calculated.

When the concentration of carbon dioxide in the working medium B increases, the solubility of the amine compound in the working medium B (water) increases, and the working medium B becomes an aqueous solution. On the other hand, when the carbon dioxide concentration in the working medium B decreases, the solubility of the amine in the working medium B (water) decreases, and the working medium B becomes a solid-liquid separated state or a liquid-liquid separated state.

In the solid-liquid separation state, the solid can be recovered by filtering the liquid or the like, and the solid can be dissolved in water to obtain a concentrated working medium B. When dissolving a solid, carbon dioxide is blown into the solution to increase the concentration of carbon dioxide in the solution and dissolve the solid.

In the case of a liquid-liquid separation state, the upper phase or lower phase is recovered using a decantation or a liquid separation funnel, or a liquid-liquid extraction device, and the phase containing a high-concentration amine compound is dissolved in water and concentrated. The finished work medium B can be obtained. When the phase containing a high-concentration amine compound is dissolved in water, carbon dioxide is blown into the solution to increase the concentration of carbon dioxide in the solution and the phase containing the high-concentration amine compound is dissolved in water.

When the solubility of the amine compound in the working medium B (water) varies greatly depending on the carbon dioxide concentration, the working medium B can be easily concentrated. Therefore, it is preferable to use an amine compound having a solubility in water of the amine compound after absorption of carbon dioxide, which is four times or more the solubility of the amine compound in water after the release of carbon dioxide.

Therefore, in the embodiment, it is possible to provide a water treatment system that can be operated at low cost and a work medium B for the water treatment system, which can efficiently carry out treatments such as desalting and concentration of the water to be treated A. It is also preferable that the water treatment system of the embodiment further has a rotating body and is used as a water treatment system in which a water flow is generated by the induction of osmotic pressure and the rotating body is rotated by the water flow to generate power.

The solute contained in the working medium B is a compound whose affinity with water changes depending on the carbon dioxide concentration. The working medium B of the embodiment has a solute loss (Js mmol / m) when the water in the water to be treated A in the first chamber 13 permeates the osmosis membrane 12 and moves to the working medium B in the second chamber 14. ² h) is low, and a high permeation flux (Jw L / m ² h) can be generated.

The specific amine compound is the compound represented by the formula (1) in FIG. The structure of the compound is measured by 1H-NMR and 13C-NMR analysis.

The amine compound of the formula (1) has a property of phase-separating into an aqueous phase and an organic solvent-based phase in which the solute is concentrated when the carbon dioxide concentration in the solution is low. When the carbon dioxide concentration is high, the amine compound of the formula (1) is highly soluble in water and is therefore dissolved in the solution. Then, when the concentration of carbon dioxide in the solution is lowered, the solubility of the amine compound in the solution is lowered, and the amine compound is separated into an aqueous phase and an organic solvent-based phase in which the solute is concentrated. By recovering the organic solvent-based phase in which the solute is concentrated, an aqueous solution in which the amine compound is concentrated can be economically obtained. Since the amine compound of the formula (1) has a high phase separation rate into an aqueous phase and an organic solvent-based phase in which a solute is concentrated, it can be economically treated with water.

R ¹ in the formula (1) is a linear alkyl chain having 1 to 3 carbon atoms. R ¹ in the formula (1) is preferably a linear alkyl chain having 3 carbon atoms.

In addition, as a specific amine compound different from the compound of the formula (1), the compound represented by the formula (2) of FIG. 2 can be mentioned. The structure of the compound is measured by 1H-NMR and 13C-NMR analysis.

The amine compound of the formula (1) has a property of phase-separating into an aqueous phase and an organic solvent-based phase in which the solute is concentrated when the carbon dioxide concentration in the solution is low. When the carbon dioxide concentration is high, the amine compound of the formula (1) is highly soluble in water and is therefore dissolved in the solution. Then, when the concentration of carbon dioxide in the solution is lowered, the solubility of the amine compound in the solution is lowered, and the amine compound is separated into an aqueous phase and an organic solvent-based phase in which the solute is concentrated. By recovering the organic solvent-based phase in which the solute is concentrated, an aqueous solution in which the amine compound is concentrated can be economically obtained. Since the amine compound of the formula (1) has a high phase separation rate into an aqueous phase and an organic solvent-based phase in which a solute is concentrated, it can be economically treated with water.

R ² in the formula (2) is a linear alkyl chain having 1 to 3 carbon atoms. Any one of R ³ to R ⁶ in the formula (2) is a methyl group or an ethyl group, and the other three are hydrogen.

The concentration of the compound represented by the formula (1) or the formula (2), which is the solute in the working medium, is the concentration of the solute in the water to be treated, the concentration of the compound represented by the formula (1) or the formula (2). It is desirable to adjust based on the characteristics. Usually, the concentration of the amine compound in the working medium is preferably 10% by mass or more and 70% by mass or less, more preferably 30% by mass or more and 70% by mass or less, and most preferably 50% by mass or more and 70% by mass or less. However, if inconvenience occurs such as when the viscosity increases, adjust in the direction of lowering the concentration. The upper limit of the concentration depends on the solubility of the substance at the time of ionization.

(Second Embodiment)
Next, a desalination system, which is an example of a water treatment system, will be described. FIG. 3 is a schematic diagram of the desalting system according to the second embodiment. In the second embodiment, the first chamber 13, the water to be treated A, the second chamber 14, the working medium B and the osmosis membrane 12 are common to the first embodiment. The water to be treated A is salt water (sodium chloride aqueous solution) such as seawater. The work medium B used in the second embodiment is the work medium B of the first embodiment. Although the reference numerals of the water to be treated, the working medium, and the water in the water treatment system are not shown in FIGS. 3 and 3, these symbols are common to the water treatment system of FIG. Since the second embodiment is a desalination system, the treated water A is salt water, but in the case of a concentration system or the like, the treated water A is not limited to the salt water, and the treated water described in the first embodiment is described. A and the like are used.

The desalting system 200 includes an osmotic pressure generator 1, a concentrator 2, a concentrating work medium tank 3, a purified water tank 4, and a reverse osmosis membrane separator 5. The osmotic pressure generator 1, the concentrator 2, the reverse osmosis membrane separator 5, and the concentrating work medium tank 3 are connected in this order to form a loop. The working medium B (draw solution) that induces osmotic pressure circulates in this loop. That is, the working medium B circulates the osmotic pressure generator 1, the concentrator 2, the reverse osmosis membrane separator 5, and the concentrating work medium tank 3 in this order. The upper and lower directions are the directions shown in the drawings. For example, the concentrating work medium tank 3 is on the upper side of the concentrator 2, and the osmotic pressure generator 1 is on the left side of the reverse osmosis membrane separator 5. ..

The water tank 15 to be treated is connected to the upper part of the treatment container 10 in which the first chamber 13 is located through a pipeline 101a. The first pump 16 is provided in the pipeline 101a. The pipeline 101b for discharging the concentrated water to be treated A is connected to the lower part of the first treatment container 11 in which the first chamber 13 is located.

The concentrator 2 is connected to the lower part of the first processing container 11 where the second chamber 14 is located through the pipeline 101e. Further, the concentrator 2 is connected to the concentrating work medium tank 3 through the pipeline 101d. The third pump 18 is provided in the pipeline 101d. It is connected to the upper part of the second processing container 51 in which the third chamber 53 is located through the pipeline 101f, and is connected to the lower part of the second processing container 51 in which the third chamber 53 is located through the pipeline 101g. The third pump 18 is provided in the pipeline 101e.

The concentration work medium tank 3 is connected to the upper part of the first processing container 11 in which the second chamber 14 is located through the pipeline 101c. The second pump 17 is provided in the pipeline 101c.

The purified water tank 4 is connected to the reverse osmosis membrane separator 5 through the pipeline 101h. A pipeline 101i for sending and recovering the purified water in the purified water tank 4 to the outside is connected to the purified water tank 4. The on-off valve 41 is provided in the pipeline 101i. For example, it is opened when the amount of purified water in the purified water tank 4 exceeds a certain amount. When the reverse osmosis membrane separator 5 is omitted, the concentrator 2 and the purified water tank are connected through the pipeline 101h.

The reverse osmosis membrane separator 5 includes, for example, an airtight second treatment container 51. The second treatment container 51 is, for example, horizontally partitioned by a reverse osmosis membrane (RO membrane or NF membrane) 52, and a third chamber 53 is formed on the left side and a fourth chamber 54 is formed on the right side. It is connected to the purified water tank 4 through a pipeline 101h. The purified water tank 4 contains water (purified water) that has moved to the fourth chamber through the reverse osmosis membrane 52 when the working medium B is concentrated.

Next, the desalting operation by the desalting system 200 shown in FIG. 3 will be described.

The first pump 16 is driven to supply water A (for example, seawater) to be treated from the water tank 15 to be treated into the first chamber 13 of the osmotic pressure generator 1 through the pipeline 101a. Before and after the supply of seawater, the second pump 17 is driven to supply the concentration work medium B from the concentration work medium tank 4 into the second chamber 14 of the osmotic pressure generator 1 through the pipeline 101c. At this time, the solute concentration of the concentration work medium B supplied to the second chamber 14 is higher than the salt concentration of the seawater supplied to the first chamber 13. Therefore, an osmotic pressure difference is generated between the seawater in the first chamber 13 and the concentration work medium B in the second chamber 14, and the water in the seawater permeates the osmotic membrane 12 and moves into the second chamber 14. .. The concentration work medium B in the second chamber 14 is an aqueous solution containing the solute of the first embodiment or the second embodiment, and exhibits a high osmotic pressure-inducing action. Therefore, when the water in the seawater in the first chamber 13 permeates the osmosis membrane 12 and moves to the concentration work medium B in the second chamber 14, a high permeation flux is generated. As a result, a large amount of water in the seawater in the first chamber 13 can be moved to the concentration work medium B in the second chamber 14, and a highly efficient desalting treatment for extracting water (pure water) from the salt water can be performed.

In the osmotic pressure generator 1, the water in the seawater moves from the first chamber 13 to the concentration work medium B in the second chamber 14, so that the seawater is discharged as concentrated seawater from the first chamber 13 through the pipeline 101b. The concentration working chamber B is diluted with the transferred water. When the water treatment system of the embodiment concentrates the liquid A to be treated, the wastewater discharged through the pipeline 101b is collected.

The dilution work medium B of the second chamber 14 is sent to the concentrator 2 through the pipeline 101d. In the concentrator 2, carbon dioxide is released from the dilution work medium B by heating the dilution work medium B or the like. The working medium B that has released carbon dioxide is phase-separated. The phase-separated work medium B is solid-liquid separated or liquid-liquid separated, and water is recovered. The recovered water moves to the third chamber 53 of the reverse osmosis membrane separator 5 through the pipeline 101f. The water transferred to the third chamber 53 may contain a small amount of the amine compound used as the solute, which is concentrated by the reverse osmosis membrane separator 5. The water in which the amine compound is concentrated passes through the pipeline 101 g and is mixed with the concentrated working medium B. The purified water moved to the fourth chamber 54 by the reverse osmosis membrane separator 5 passes through the pipeline 101h and moves to the purified water tank 4.

In the concentrator 2, carbon dioxide is absorbed by the concentrated working medium B, and the amine compound is dissolved in water again. When solid-liquid separation is performed, the concentration of the public working medium B may be adjusted by adding water as necessary. The concentration work medium B that has become an aqueous amine solution is sent from the third chamber 53 to the concentration work medium tank 3. The concentration work medium B in the concentration work medium tank 3 is supplied into the second chamber 14 of the osmotic pressure generator 1 by driving the second pump 17, and water (pure water) is taken out from the salt water as described above. Used for desalination.

On the other hand, the water (pure water) that has moved to the fourth chamber 24 is sent to the pure water tank 26 through the pipeline 101i. When the amount of water in the purified water tank 4 exceeds a certain amount, the on-off valve 41 is opened and sent to the outside through the pipeline 101h to collect the water.

Therefore, it is possible to provide a low-cost operationable desalination system capable of efficiently performing desalination treatment of seawater (recovery of pure water). Such a system can be operated at low cost even in a water treatment system for concentrating.

In the desalination system 200 shown in FIG. 3, the osmotic pressure generator formed the first chamber 13 and the second chamber 14 by horizontally partitioning the first treatment container 11 by a osmotic membrane, but the first treatment container was formed. The first chamber 13 may be formed and the second chamber 14 may be formed by partitioning the first chamber 13 into upper and lower parts by an osmosis membrane.

When the solute concentration of the work medium B is lowered by the desalting treatment, it is preferable to add the solute in the concentration work medium tank 4 or the like.

In the desalting system 200 shown in FIG. 3, the concentration of the dilution work medium B is not limited to the case where the reverse osmosis membrane separator 5 provided with the reverse osmosis membrane (RO membrane, NF membrane) is used, and the water in the dilution work medium B is removed. Any device may be used as long as it is used.

(Third Embodiment)
Next, the osmotic power generation system 300, which is an example of the water treatment system according to the third embodiment, will be described. FIG. 4 is a schematic diagram of the osmotic power generation system according to the third embodiment. In FIG. 4, the same members as those in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted. The work medium used in the third embodiment is the work medium B of the first embodiment.

The osmotic pressure power generation system 300 includes an osmotic pressure generator 1 that generates a water flow and a rotating body 6 that generates power with the water flow generated by the osmotic pressure generator 1.

The osmotic pressure power generation system 300 partitions a first chamber 13 for accommodating water, a second chamber 14 for accommodating a working medium B (draw solution) for inducing osmotic pressure, and a first chamber 13 and a second chamber 14. The osmotic film 12 is provided, the pressure exchanger 7 connected to the second chamber 14, and the rotating body 6 connected to the pressure exchanger 7. According to such a water treatment system, the water in the first chamber 13 permeates through the osmotic film 12 due to the osmotic pressure difference generated between the water in the first chamber 13 and the working medium B in the second chamber 14. It moves to the work medium B in the second chamber 14. The rotating body 62 is rotated by the water flow accompanying the movement of water to the work medium B to generate electricity.

The third embodiment is an aqueous solution in which the working medium B contains the solute of the embodiment, and exhibits a high osmotic pressure inducing action. Therefore, when the water in the first chamber 13 permeates the osmosis membrane 12 and moves to the work medium B in the second chamber 14, a high permeation flux can be generated. As a result, the working medium B to which the water is moved becomes a water stream having a high pressure, so that the rotating body 6 can be rotated at a higher speed to generate electricity. Therefore, it is possible to provide a water treatment system that can be operated at low cost and can efficiently rotate the rotating body 6 to generate electricity.

As the rotating body 82, for example, a turbine or a water turbine can be used.

The osmotic pressure power generation system 300 is a pressure exchanger 7 and a rotating body 6 in a pipeline 101e connected to the lower part (work medium B outlet side) of the first processing container 11 in which the second chamber 14 of the osmotic pressure generator 1 is located. Are provided in this order along the flow direction of the work medium B. Further, in the pipeline 101c connecting the upper part of the first processing container 11 in which the second chamber 14 is located and the concentration work medium tank 3, the pipeline 101c portion on the downstream side in the flow direction of the work medium B from the second pump 17. Is connected to the upper part of the first processing container 11 in which the second chamber 14 is located via the pressure exchanger 7. That is, the second chamber 14 is located in the diluting work medium B having the flow flux generated when water permeates the osmotic membrane 12 from the first chamber 13 and moves to the second chamber 14 in the osmotic pressure generator 1. It flows out from the lower part of the first processing chamber 11 through the pipeline 101e provided with the pressure exchanger 7. During this time, the pipeline 101c through which the concentration work medium B flowing out of the concentration work medium tank 3 flows passes through the pressure exchanger 7. Therefore, the concentration work medium B is pressure-exchanged with the dilution work medium B flowing out of the second chamber 14 by the pressure exchanger 7, the dilution work medium B lowers the pressure, and the concentration work medium B flowing to the rotating body 6 is Increase pressure.

In the osmotic pressure power generation system 300, water is housed in the water tank 15 to be treated.

Next, the power generation operation by the osmotic pressure power generation system 300 shown in FIG. 4 will be described.
The first pump 16 is driven to supply water from the water tank 15 to be treated into the first chamber 13 of the osmotic pressure generator 1 through the pipeline 101a. Before and after the supply of water, the second pump 17 is driven to supply the concentration work medium B from the concentration work medium tank 3 into the second chamber 14 of the osmotic pressure generator 1 through the pipeline 101c. The concentration work medium B supplied to the second chamber 14 has a sufficiently high concentration with respect to the solvent-only water supplied to the first chamber 13. Therefore, an osmotic pressure difference is generated between the water in the first chamber 13 and the concentration work medium B in the second chamber 14, and the water permeates the osmotic membrane 12 and moves into the second chamber 14. At this time, the working medium B in the second chamber 14 is an aqueous solution containing the solute of the embodiment and exhibits a high osmotic pressure inducing action. Therefore, when the water in the first chamber 13 permeates the osmosis membrane 12 and moves to the work medium B in the second chamber 14, a high permeation flux is generated. As a result, a large amount of water in the first chamber 13 can be transferred to the concentration work medium B in the second chamber 14, and a dilution work medium B having a high pressure diluted with water is produced. The water in the first chamber 13 is discharged through the pipeline 101b.

The dilution work medium B having a high pressure in the second chamber 14 is sent to and stored in the concentrator 2 through the pipeline 101e. The pressure exchanger 7 and the rotating body 6 are provided in the pipeline 101e in this order along the flow direction of the work medium B.

Therefore, as described above, the pressure exchanger 7 has a high pressure flowing from the concentrating work medium tank 3 through the pipeline 101c and from the second chamber 14 (through the rotating body 6) through the pipeline 101e. Pressure is exchanged with the dilution work medium B to reduce the pressure of the dilution work medium B and increase the pressure of the concentration work medium B. By pressure exchange, the diluting work medium B having an appropriate pressure flows into the rotating body 6 and efficiently rotates it to generate electricity. Further, the concentration work medium B having an appropriate pressure is supplied to the second chamber 14 by pressure exchange.

In the concentrator 2, the working medium B is concentrated and purified by the reverse osmosis membrane separator 5 in the same manner as in the second embodiment, and the working medium B of the concentrated amine aqueous solution is stored in the concentrating working medium tank 3. ..

In the osmotic pressure power generation system 300 shown in FIG. 4, the osmotic pressure generator formed the first chamber 13 and the second chamber 14 by horizontally partitioning the first processing container 11 by the osmotic membrane 12. The processing container 11 may be vertically partitioned by an osmotic membrane to form the first chamber 13 and the second chamber 14.

In the osmotic pressure power generation system 300 shown in FIG. 4, the water in the first chamber 13 of the osmotic pressure generator 1 was sent to the outside through the pipeline 101b, but the pipeline 101b was connected to the water tank 15 to be treated and treated. A loop may be formed in the water tank 15, the pipeline 101a, the first chamber 13 of the osmotic pressure generator 1, and the pipeline 101b.

Hereinafter, examples will be described.

The forward osmosis test was performed as follows. A CTA-ES membrane manufactured by HTI was set in the FO cell, pure water was put as water to be treated on the active surface side of the membrane, and then a working medium was put on the support layer side. Sufficient carbon dioxide is bubbled in advance on the work medium placed on the support layer side to form an amine aqueous solution. The time when the work medium was put in was set to 0 minutes, and the work medium was allowed to stand for 20 minutes. After the test, the weight of the liquid on the active surface side was measured, and the permeation flux (Jw) was calculated from the difference before and after the test with the specific gravity of the liquid as 1. In addition, the total organic carbon concentration in the liquid on the active surface side after the test was measured with a total organic carbon meter, and the cation concentration was measured with an ion chromatograph to calculate the solute loss (Js). Further, the working medium after the test was heated to 80 ° C. and nitrogen gas was bubbled to concentrate the working medium. Then, in the phase-separated example (comparative example), the phase separation rate (%) was obtained from the following calculation. The phase separation rate (%) ([100- (B × D) / (A × C)] × 100) is the concentration A (mg / L) of the amine compound in the amine aqueous solution in which carbon dioxide is bubbled and the volume C ( L), the concentration B (mg / L) of the amine compound of the aqueous phase after phase separation and its volume D (L) are used for determination. Table 1 shows the concentration of the solute contained in the working medium and the experimental results. The solute contained in the working medium is the compound shown in FIGS. 2 and 5. Example 1 is a linear alkyl chain in which R ¹ has 3 carbon atoms. In Example 2, R ² is a linear alkyl chain having 3 carbon atoms, R ⁴ is a methyl group, and R ³ , R ⁵ and R ⁶ are hydrogen.

From Table 1, it was confirmed that in the examples using the compounds of the formulas (1) and (2), the working medium can be concentrated by manipulating the carbon dioxide concentration in the working medium. Since the Js / Jw of the examples are all 0.5 or less, the loss of the work medium due to the FO treatment is small, and water can be separated at low cost. In addition, since the phase separation rates of the examples are all very high, the load on the membrane separation assumed for post-treatment is reduced when recovering water, and water can be separated at low cost.
Further, by generating electricity using the water flow generated by these osmotic pressure actions, it is possible to generate electricity at low cost.
In the specification, some elements are represented only by element symbols.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

A ... Water to be treated,
B ... Working medium,
C ... water 1 ... osmotic pressure generator,
2 ... Concentrator,
3 ... Concentration work medium tank,
4 ... Purified water tank,
5 ... Reverse osmosis membrane separator,
11 ... First processing container,
12 ... osmosis membrane,
13 ... Chamber 1,
14 ... 2nd chamber,
15 ... Water tank to be treated,
16 ... 1st pump,
17 ... 2nd pump,
18 ... 3rd pump,
41 ... On-off valve,
51 ... Second processing container,
52 ... Reverse osmosis membrane (RO membrane, NF membrane),
53 ... Third chamber,
54 ... 4th chamber,
100 ... Water treatment system,
101 ... Pipeline,
200 ... Desalting system,
300 ... Osmotic power generation system

Claims (9)

An osmotic pressure generator having a first treatment container provided with an osmotic membrane that separates a first chamber containing water to be treated and a second chamber containing an osmotic pressure-inducing draw solution .
It has a carbon dioxide emitting means for releasing carbon dioxide from the draw solution , a phase separating means for separating the phase-separated draw solution, and a concentrator having a carbon dioxide introducing means for absorbing carbon dioxide in the draw solution .
The draw solution contains an amine compound and contains
The amine compound is a compound represented by the formula (1) or (2) and is represented by the formula (1) or (2).
R ¹ in the formula (1) is a linear alkyl chain having 1 to 3 carbon atoms.
R ² in the formula (2) is a linear alkyl chain having 1 to 3 carbon atoms.
A water treatment system in which any one of R ³ to R ⁶ in the formula (2) is a methyl group or an ethyl group.

The water treatment system according to claim 1, wherein any one of R ³ to R ⁶ in the formula (2) is a methyl group and the other three are hydrogen. The water treatment system according to claim 1 or 2, wherein the concentration of the amine compound in the draw solution is 10% by mass or more and 70% by mass or less. The water treatment system according to any one of claims 1 to 3, wherein the amine compound in the draw solution is solid-liquid separated or liquid-liquid separated when the carbon dioxide concentration decreases. The water treatment system according to any one of claims 1 to 4, wherein the solubility of the amine compound in water after absorption of carbon dioxide is four times or more the solubility of the amine compound in water after release of carbon dioxide. .. The water treatment system according to any one of claims 1 to 5 further comprises a rotating body.
Due to the induction of the osmotic pressure, a water flow is generated.
A water treatment system that generates electricity by rotating the rotating body with the water flow. The draw solution used in the water treatment system according to any one of claims 1 to 6. Contains amine compounds
The amine compound is a compound represented by the formula (1) or (2) and is represented by the formula (1) or (2).
R ¹ in the formula (1) is a linear alkyl chain having 1 to 3 carbon atoms.
R ² in the formula (2) is a linear alkyl chain having 1 to 3 carbon atoms.
Any one of R ³ to R ⁶ in the formula (2) is a draw solution used in a water treatment system having a methyl group or an ethyl group.

Any one of R ³ to R ⁶ in the above formula (2) is a methyl group, and the other three are hydrogen.
The concentration of the amine compound in the draw solution used in the water treatment system is 10% by mass or more and 70% by mass or less.
The amine compound in the draw solution used in the water treatment system undergoes solid-liquid separation or liquid-liquid separation when the carbon dioxide concentration decreases.
The draw solution used in the water treatment system according to claim 8, wherein the solubility of the amine compound in water after absorption of carbon dioxide is four times or more the solubility of the amine compound in water after release of carbon dioxide.

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