Amine-containing water concentration system and apparatus and carbon dioxide recovery system

Abstract

This invention relates to a system for concentrating treated water containing amines and a carbon dioxide recovery system. The invention provides an amine-containing water concentration system that can concentrate useful amines reacting with carbon dioxide into an absorbent for reuse, and reduce the amount of wastewater containing amine compounds, as well as a carbon dioxide recovery system equipped with the amine-containing water concentration system. The amine-containing water concentration system according to an embodiment includes: an osmotic pressure generator comprising a treatment container, and a first chamber disposed within the treatment container for supplying treated water, a second chamber for containing a working medium, and a semi-permeable membrane for separating the first and second chambers; and a carbon dioxide introduction mechanism for introducing carbon dioxide into the treated water.

Description

[0001] [Citation of related applications such as priority-based applications]

[0002] This application claims priority based on Japanese Patent Application No. 2021-048952 (filed on March 23, 2021). The entire contents of that application are incorporated herein by reference. Technical Field

[0003] Embodiments of the present invention relate to a system for concentrating treated water containing amines and a carbon dioxide recovery system. Background Technology

[0004] In recent years, carbon dioxide in the exhaust gases emitted from combustion systems in thermal power plants and other sources has become a contributing factor to global warming, prompting ongoing efforts to reduce emissions and recover carbon dioxide. As a wet method for recovering carbon dioxide from exhaust gases, chemical absorption using an absorbent similar to an aqueous solution of alkanolamine is well-known.

[0005] A carbon dioxide recovery system employing this chemical absorption method generally includes an absorption section and a regeneration section. In the absorption section, waste gas is brought into contact with an absorbent liquid, causing the carbon dioxide in the waste gas to dissolve in the absorbent liquid, thus removing the carbon dioxide from the waste gas. The absorbent liquid that has absorbed carbon dioxide (rich carbon dioxide solution) is then transported from the absorption section to the regeneration section, where it is heated to release a high concentration of carbon dioxide. The absorbent liquid that has released carbon dioxide (lean solution), now regenerated and capable of absorbing carbon dioxide, is then sent from the regeneration section to the absorption section. Thus, in this carbon dioxide recovery system, carbon dioxide is removed from the waste gas by circulating the absorbent liquid between the absorption section and the regeneration section, while the absorbent liquid can be reused repeatedly.

[0006] In a carbon dioxide recovery system, if the waste gas and absorbent come into contact within the absorption section, the carbon dioxide in the waste gas is absorbed by the absorbent, and simultaneously, a portion of the absorbent is released from the absorption section along with the waste gas. To suppress the diffusion of absorbent components accompanying the waste gas into the atmosphere, a waste gas scrubbing section (diffusion suppression section) is installed downstream of the absorption section. The waste gas scrubbing section washes the waste gas with scrubbing water, preventing absorbent components from leaking from the carbon dioxide recovery system to the outside. The scrubbing water, which has recovered absorbent components from the waste gas, can be reused or discarded as wastewater.

[0007] Furthermore, it is known that the high concentration of carbon dioxide gas released from the regeneration unit is accompanied by absorbent components. Therefore, by cooling the carbon dioxide gas and condensing the water vapor released along with the carbon dioxide gas, the condensate containing absorbent components is discharged as wastewater.

[0008] Thus, in the exhaust gas scrubbing section and the regeneration section, scrubbing water and condensate are discharged. Summary of the Invention

[0009] The wastewater from carbon dioxide recovery systems cannot be directly discharged because it contains amine compounds, requiring very high wastewater treatment costs.

[0010] Embodiments of the present invention provide an amine-containing water concentration system that can concentrate useful amines that react with carbon dioxide in the wastewater as an absorbent for reuse and reduce the amount of wastewater containing amine compounds, and a carbon dioxide recovery system having the amine-containing water concentration system.

[0011] According to an embodiment, an amine-containing water concentration system is provided, which is a system for concentrating treated water containing amine, wherein the system comprises: an osmotic pressure generator including a treatment container and a semi-permeable membrane disposed within the treatment container for separating a first chamber for supplying treated water and a second chamber for supplying a working medium that generates positive osmotic pressure; and a carbon dioxide introduction mechanism for introducing carbon dioxide into the treated water in the first chamber. Attached Figure Description

[0012] Figure 1 This is a simplified diagram illustrating the amine-containing water concentration system of the first embodiment.

[0013] Figure 2 This is a simplified diagram illustrating the amine-containing water concentration system of the second embodiment.

[0014] Figure 3 This is a simplified diagram illustrating the amine-containing water concentration system of the third embodiment.

[0015] Figure 4 This is a simplified diagram illustrating the amine-containing water concentration system of the fourth embodiment.

[0016] Figure 5 This is a simplified diagram illustrating the carbon dioxide recovery system of the fifth embodiment.

[0017] Figure 6 This is a simplified diagram illustrating the carbon dioxide recovery system of the sixth embodiment.

[0018] (Symbol Explanation)

[0019] 1 – Amine-containing water concentration system; 10, 71 – Osmoelectric generator; 12, 73 – Chamber 1; 13, 74 – Chamber 2; 14, 75 – Semi-permeable membrane; 21, 77 – Carbon dioxide introduction mechanism; 22 – Pump; 23 – Filtration section; 24, 79 – Working medium regeneration device; 40 – Carbon dioxide recovery system; 50 – Absorption tower; 60 – Regeneration tower; 76 – Washing water storage tank. Detailed Implementation

[0020] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Unless otherwise specified, pH and other values ​​obtained by measurement are measured at atmospheric pressure and 25°C.

[0021] (First Embodiment)

[0022] Figure 1 This is a simplified diagram illustrating the amine-containing water concentration system of the first embodiment.

[0023] The amine-containing water concentration system 1 according to the first embodiment includes an osmotic pressure generator 10. The osmotic pressure generator 10 includes a processing container 11, a first chamber 12 and a second chamber 13 disposed in the processing container 11, and a semi-permeable membrane 14 for separating the first chamber 12 and the second chamber 13.

[0024] The first chamber 12 of the treatment container 11 can contain and supply water to be treated. The second chamber 13 of the treatment container 11 can contain the working medium.

[0025] A carbon dioxide introduction mechanism 21 is provided at the front end of the osmotic pressure generator 10. A flow path 31 for introducing treated water containing amines is connected to the carbon dioxide introduction mechanism 21. The carbon dioxide introduction mechanism 21 is connected to the treatment container 11 containing the first chamber 12 via a flow path 32. A flow path 33 for discharging the concentrated water generated in the first chamber 12 is connected to the treatment container 11 containing the first chamber 12. The generated concentrated water contains amine compounds. In this specification, amine compounds are sometimes simply referred to as amines. A flow path 34 for conveying the working medium into the second chamber 13 is connected to the treatment container 11 containing the second chamber 13. A flow path 35 for discharging the working medium into the second chamber 13 is connected to the treatment container 11 containing the second chamber 13.

[0026] The semi-permeable membrane 14 can be a forward osmosis membrane or a reverse osmosis membrane. The semi-permeable membrane 14 can be, for example, a flat membrane, a hollow fiber membrane, or a tubular membrane. The shape of the semi-permeable membrane 14 is not particularly limited; examples include spiral, flat and frame, linear, and cross-wound types. The forward osmosis membrane used in the semi-permeable membrane 14 has a cross-section with an integrated support layer and active layer, selectively allowing water to permeate. The raw materials are not particularly limited; for example, they are preferably formed from cellulose acetate, polyamide, polyethyleneimine, polysulfone, and polybenzimidazole.

[0027] The reverse osmosis membrane used in the semi-permeable membrane 14 has a support layer and an active layer, selectively allowing water to permeate. The raw materials are not particularly limited, but are preferably formed from polyamide, polyvinyl alcohol, polysulfone, polyolefin, polyvinylidene fluoride, etc.

[0028] The form of the carbon dioxide introduction mechanism 21 is not limited as long as it has the function of dissolving carbon dioxide in the water being treated. That is, "capable of introducing carbon dioxide" means having the function of dissolving and containing carbon dioxide in the water being treated. Introducing carbon dioxide can be achieved, for example, by injecting the water being treated into a tank filled with carbon dioxide-containing gas to bring the carbon dioxide into contact with the water, by bubbling carbon dioxide into the water being treated, or by dissolving carbon dioxide by pressurizing it. Examples of carbon dioxide introduction mechanisms 21 include tanks filled with carbon dioxide-containing gas, devices that bubble carbon dioxide-containing gas, and devices that dissolve carbon dioxide by pressurizing it into the water being treated. Furthermore, from the viewpoint of treatment speed, the volume concentration of carbon dioxide in the gas introduced from the carbon dioxide introduction mechanism 21 is preferably high, preferably 5% to 100%, and more preferably 10% to 100%.

[0029] Figure 1 In this configuration, the carbon dioxide introduction mechanism 21 and the first chamber 12 are connected via flow path 32. However, carbon dioxide can also be dissolved in the water being treated by directly blowing it into the first chamber. In this case, flow path 32 can be omitted, and the carbon dioxide introduction mechanism can be integrated with the first chamber 12.

[0030] The concentration operation of amine-containing treated water using the amine-containing water concentration system according to the first embodiment will be described.

[0031] The treated water is introduced into the carbon dioxide introduction mechanism 21 through flow path 31, where carbon dioxide is dissolved in the treated water. The treated water containing amine and dissolved carbon dioxide is supplied to the first chamber 12 of the osmotic pressure generator 10, which is divided by a semi-permeable membrane 14, through flow path 32. Before and after the treated water is supplied to the first chamber 12, the working medium is supplied to the second chamber 13 through flow path 34. At this time, the molar concentration of ions in the working medium supplied to the second chamber 13 is higher than that in the treated water supplied to the first chamber 12. Therefore, an osmotic pressure difference is generated between the treated water in the first chamber 12 and the working medium in the second chamber 13, and the water in the treated water permeates through the semi-permeable membrane 14 and moves towards the working medium in the second chamber 13. Through the movement of permeate water through the semi-permeable membrane 14, the treated water in the first chamber 12 can be concentrated. By connecting flow path 33 and flow path 32, it is circulated in the first chamber 12, thereby achieving higher concentration. On the other hand, the working medium in the second chamber 13 is diluted by the moving permeate water and discharged to the outside through the flow path 35. By connecting the flow path 35 and the flow path 34, it is also possible to circulate the working medium in the second chamber 13.

[0032] Preferably, the pH of the amine-containing water to be treated, in which carbon dioxide has been dissolved by the carbon dioxide introduction mechanism 21, is adjusted to a range of 6 to 9. Furthermore, from the viewpoint of the durability of the semipermeable membrane 14, it is more preferable to adjust the pH of the water to be treated to 7 to 8.

[0033] The working medium can induce positive osmotic pressure within chamber 2, 13. For example, a medium containing at least one compound selected from inorganic salts, amine compounds, sugars, polarity-reversing compounds, and compounds with a lowest critical solution temperature (LCST) can be used. These compounds can be low-molecular-weight or high-molecular-weight. The working medium can also be a mixed solution of multiple salts, such as seawater. The working medium can be in the form of an aqueous solution, or in the form of nano-sized particles or gels. When using seawater, it can be supplied directly from the sea into chamber 2.

[0034] According to the first embodiment, carbon dioxide can be introduced into the treated water containing amines via the carbon dioxide introduction mechanism 21. A portion of the amine compounds in the treated water are useful amine compounds that react with the introduced carbon dioxide. It is known that, generally speaking, under conditions of 25°C, atmospheric conditions, and an acid dissociation constant pKa = 7 or higher, the amine compounds that react with carbon dioxide are cations with bicarbonate as counterions, or become carbamates through the addition of carbon dioxide. That is, the amine compounds in the treated water that react with carbon dioxide become charged through ionization. On the other hand, there are unused amine compounds in the treated water that do not react with carbon dioxide. These unused amine compounds are difficult to charge under the aforementioned conditions.

[0035] When treated water containing both useful and unused amine compounds is applied to the amine-containing water concentration system according to the first embodiment, the useful amine compounds become charged by reacting with carbon dioxide introduced from the carbon dioxide introduction mechanism 21, while the unused amine compounds do not react with the introduced carbon dioxide and are difficult to charge. When the treated water containing both useful and unused amine compounds containing introduced carbon dioxide is conveyed to the first chamber 12 of the osmotic pressure generator 10, and the working medium is conveyed to the second chamber 13, the useful amine compounds, due to their charge, generate a repulsive force relative to the semipermeable membrane 14, making it difficult to pass through the semipermeable membrane 14 and easily remaining in the treated water. The unused amine compounds in the treated water, being difficult to charge, easily pass through the semipermeable membrane 14 and move towards the working medium in the second chamber 13.

[0036] As a result, the treated water discharged from the first chamber 12 of the osmotic pressure generator 10 contains less water and unused amine compounds compared to the treated water before it was introduced into the first chamber 12, while maintaining the content of useful amine compounds. That is, the treated water in the first chamber 12 can be discharged in a concentrated state by relatively increasing the content of useful amine compounds.

[0037] In addition, examples of unused amine compounds that do not react with carbon dioxide include 1-nitrosoperpiperidine, 1,4-dicarboxypiperazine, tetrahydronaphthiazoline hydrochloride, and 2,5-pyrrolidone. On the other hand, examples of useful amine compounds that react with carbon dioxide include alkanolamines, cyclic amines, and diamines.

[0038] As previously described, the amine-containing water concentration system 1 according to the first embodiment can selectively concentrate useful amine compounds that react with carbon dioxide in amine compounds contained in the water being treated by utilizing the property of a semi-permeable membrane 14 that produces a difference in membrane permeability between charged and uncharged compounds.

[0039] Furthermore, in the amine-containing water concentration system 1 according to the first embodiment, the osmotic pressure generator 10, which includes a forward osmosis membrane in the semi-permeable membrane 14, can operate at a lower pressure. Even under such conditions, the high concentration of the amine-containing water can be achieved through the properties of the semi-permeable membrane 14 and the osmotic pressure caused by the working medium. Compared to the reverse osmosis membrane method, which operates at low pressure, the forward osmosis membrane can be used with a structure having a thinner support layer and a relaxed active layer. Although forward osmosis also occurs with the reverse osmosis membrane, the forward osmosis membrane can recover amine more efficiently than the reverse osmosis membrane when operating at the same flow rate.

[0040] The inventors discovered that when a semipermeable membrane is used, the permeation rates of amines that absorb carbon dioxide and those that do not are different. Therefore, by using a semipermeable membrane, it is possible to separate amines that absorb carbon dioxide from those that do not, and to obtain concentrated water containing useful amines that exhibits an osmotic pressure of over 800 mOsm at 25°C.

[0041] Furthermore, in the concentrated water obtained from the amine-containing water concentration system 1 according to the first embodiment, since useful amine compounds that can react with carbon dioxide, i.e. amine compounds with carbon dioxide recovery capabilities, are concentrated in greater quantities, the concentrated water can be reused as the absorbent in the carbon dioxide recovery system according to the fifth and sixth embodiments described later.

[0042] The amine-containing water concentration system 1 according to the first embodiment can also be configured to have multiple osmotic pressure generators 10. The multiple osmotic pressure generators 10 can be arranged in series, in parallel, or in a hybrid manner.

[0043] In the first embodiment, the working medium is supplied to the second chamber 13, but this is not a limitation, as long as the second chamber can hold the working medium. That is, the second chamber does not necessarily need to be connected to the flow path 34 that supplies the working medium to the second chamber. Furthermore, the working medium may or may not be connected to the working medium regeneration device described later in the second chamber.

[0044] The amine-containing water concentration system described in the first embodiment above can be considered as an apparatus. That is, as an amine-containing water concentration apparatus, it can include: an osmotic pressure generator comprising a treatment container, a first chamber disposed within the treatment container for supplying water to be treated, a second chamber for containing a working medium, and a semi-permeable membrane separating the first and second chambers; and a carbon dioxide introduction mechanism for introducing carbon dioxide into the water to be treated.

[0045] (Second Implementation)

[0046] Figure 2 This is a simplified diagram illustrating the amine-containing water concentration system 1 of the second embodiment. Figure 2 In the above, for those described in the first embodiment Figure 1 The same components are marked with the same symbols, and the descriptions are omitted. In the amine-containing water concentration system 1 according to the second embodiment, a pump 22 is installed on the flow path 32 connecting the carbon dioxide introduction mechanism 21 and the first chamber 12. The pump 22 has the function of pressurizing the treated water when it is transported through the flow path 32 to the first chamber 12 of the osmotic pressure generator 10 after the treated water in which carbon dioxide has been dissolved by the carbon dioxide introduction mechanism 21 is transported.

[0047] It is preferable to set the pressure at which the water to be treated is pressurized by pump 22 to a relatively low pressure. Therefore, for example, it is preferable to set the maximum ejection pressure to below 1 MPa.

[0048] According to the second embodiment, by using pump 22 to pressurize the treated water containing amine and incorporating carbon dioxide and introducing it into the first chamber 12, the water in the treated water in the first chamber 12 can permeate more efficiently from the semipermeable membrane 14 to the second chamber 13.

[0049] (Third Implementation)

[0050] Figure 3 This is a simplified diagram illustrating the amine-containing water concentration system 1 of the third embodiment. Figure 3 In the above, for those described in the first embodiment Figure 1 For the same components, use the same symbols and omit the descriptions.

[0051] The amine-containing water concentration system 1 according to the third embodiment is equipped with a filter section 23 on the first flow path 31 for filtering solids in the water to be treated.

[0052] According to the amine-containing water concentration system 1 of the third embodiment, since the solids contained in the water to be treated can be removed by the filter section 23 and the cleaner water to be treated can be delivered to the first chamber 12 of the osmotic pressure generator 10, the maintenance frequency of the membrane can be reduced.

[0053] In the third embodiment, the pump described in the second embodiment may also be included.

[0054] (Fourth implementation)

[0055] Figure 4 This is a simplified diagram illustrating the amine-containing water concentration system 1 according to the fourth embodiment. Figure 4 In the above, for those described in the first embodiment Figure 1 For the same components, use the same symbols and omit the descriptions.

[0056] The amine-containing water concentration system 1 according to the fourth embodiment further includes a working medium regeneration device 24. The working medium regeneration device 24 is connected to the processing container 11 containing the second chamber 13 of the osmotic pressure generator 10 via a flow path 34. The processing container 11 containing the second chamber 13 is connected to the working medium regeneration device 24 via a flow path 35. That is, a working medium circulation system is formed in which the working medium flows through the working medium regeneration device 24, the flow path 34, the second chamber 13, and the flow path 35, and then returns to the working medium regeneration device 24.

[0057] The working medium regeneration device 24 circulates the diluted working medium by allowing water in the treated water in the first chamber 12 to move through the semi-permeable membrane 14. High-concentration working medium can be regenerated by separating the water from the working medium. When used as a working medium exhibiting stimuli responsiveness such as temperature response, magnetic field response, electric field response, pH response, volatility, and CO2 response, the working medium regeneration device 24 can also be configured to regenerate the working medium by applying stimulation to the diluted working medium, separating the water from the working medium, and removing it through the sixth flow path 36. Furthermore, the working medium regeneration device 24 can also be configured to remove the water from the diluted working medium using methods such as membrane distillation to regenerate a high-concentration working medium. The water discharged from the flow path 36 can also be returned to a water supply tank or similar device within the CCUS (Carbon Capture Utility System) for reuse.

[0058] According to this fourth embodiment, the working medium is supplied from the working medium regeneration device 24 to the second chamber 13 through the fourth flow path 34 in the working medium circulation system. Water from the treated water in the first chamber 12 permeates through the semi-permeable membrane 14 and is transported, diluted with this water, to the working medium regeneration device 24 through the fifth flow path 35. Here, the water is removed, and a high-concentration working medium is regenerated. The regenerated working medium is then circulated back to the second chamber 13 through the fourth flow path 34 for reuse.

[0059] Therefore, by reducing the amount of working medium used and the amount of waste, a low-cost amine-containing water concentration system can be achieved.

[0060] Alternatively, in the fourth embodiment, a purification device (not shown) can be installed, for example, on the sixth flow path 36, to remove small amounts of working medium mixed in with the permeate water recovered from the sixth flow path 36. This improves the purity of the permeate water. Preferably, the removed working medium is returned to the second chamber 13 or its flow path. Since the working medium gradually decreases during circulation due to mixing with the permeate water, it is necessary to replenish the working medium to this extent; therefore, it is preferable to reuse it through recycling. The purification device is preferably configured to correspond to the properties of the working medium. By introducing this purification device, the recovery rate of the working medium can be improved.

[0061] In the fourth embodiment, the pump described in the second embodiment and the filter unit described in the third embodiment may also be included.

[0062] (Fifth Embodiment)

[0063] Reference Figure 5 The carbon dioxide recovery system according to the fifth embodiment will be described in detail.

[0064] Figure 5 This is a simplified diagram of the carbon dioxide recovery system according to the fifth embodiment. The carbon dioxide recovery system 40 includes: an absorption tower 50 and a regeneration tower 60 with a liquid disperser (not shown) at the top, and an amine-containing water concentration system 70.

[0065] A waste gas inlet flow path 101 is connected near the lower part of the absorption tower 50. An absorbent supply tank 51 is connected above the connection of the waste gas inlet flow path 101 near the lower part of the absorption tower 50 via a flow path 102, allowing the absorbent in the tank to be transported into the absorption tower 50. One end of a flow path 103 is connected to the lower part of the absorption tower 50, and the other end is connected to a second liquid disperser (not shown) in the regeneration tower 60. The carbon dioxide-rich liquid stored in the lower part of the absorption tower 50 can be transported to the upper part of the regeneration tower 60 via this flow path 103. A heat exchanger 52 is installed on the flow path 103.

[0066] The top of the absorption tower 50 is connected to the diffusion suppression section 53 via a flow path 104, through which the carbon dioxide desorbed gas, accompanied by the absorbent liquid, is transported to the diffusion suppression section 53. In the diffusion suppression section 53, the absorbent liquid component (amine) accompanying the carbon dioxide desorbed gas is washed with wash water to prevent its diffusion into the environment. Therefore, wash water containing amine (the treated water described later) is temporarily stored in the diffusion suppression section 53. Furthermore, the treated gas from the diffusion suppression section 53 is discharged outside the system via a flow path 105.

[0067] The regeneration tower 60 is heated by the heat from the reboiler 61, releasing carbon dioxide from the carbon dioxide-rich solution conveyed from flow path 103. One end of flow path 108 is connected to the lower part of the regeneration tower 60, and the other end is connected to a liquid disperser (not shown) in the absorption tower 50. The carbon dioxide-lean solution stored in the lower part of the regeneration tower 60 can be conveyed through flow path 108 to the liquid disperser (not shown) in the upper part of the absorption tower 50. Flow path 108 intersects with flow path 103 through heat exchanger 52.

[0068] The top of the regeneration tower 60 is connected to the gas purification section 62 via flow path 109. The desorbed carbon dioxide in the regeneration tower 60 can be transported to the gas purification section 62 via flow path 109, where the desorbed carbon dioxide is purified. The purified carbon dioxide is then recovered to a carbon dioxide recovery section (not shown) via flow path 110.

[0069] The amine-containing water concentration system 70 includes an osmotic pressure generator 71. The osmotic pressure generator 71 includes a first chamber 73 disposed within a processing container 72, a second chamber 74 capable of containing a working medium that generates positive osmotic pressure, and a semi-permeable membrane 75 separating the first chamber and the second chamber.

[0070] The diffusion inhibition section 53 is connected to the wash water storage tank 76 via flow path 111, allowing the amine-containing wash water (treated water) within the diffusion inhibition section 53 to be transported to the wash water storage tank 76 via flow path 111. The wash water storage tank 76 is connected to the treated water tank 77 via flow path 112 and to the absorbent supply tank 51 via flow path 118. The treated water tank 77 is connected to the processing container 72 containing the first chamber 73 of the osmotic pressure generator 71 via flow path 113. Furthermore, the treated water tank 77 includes a carbon dioxide introduction mechanism. That is, the wash water (treated water) in the wash water storage tank 76 can be supplied to the absorbent supply tank 51 as absorbent, and on the other hand, after carbon dioxide is introduced into the treated water tank 77 via the carbon dioxide introduction mechanism, a portion of the wash water is transported to the first chamber 73. The carbon dioxide introduction mechanism of the treated water tank 77 can be the same as that described in the first embodiment. The processing container 72 containing chamber 1 73 is connected to the water tank 77 to be treated via flow path 114. The concentrated water formed by permeating water from the semi-permeable membrane 75 into chamber 2 74 in chamber 1 73 is returned (circulated) to the water tank 77 to be treated via flow path 114, and then returned to the washing water storage tank 76 via flow path 121.

[0071] A working medium holding tank 78 containing a high concentration of working medium (e.g., seawater) is connected to a processing container 72 containing the second chamber 74 via a flow path 115. The working medium in the holding tank 78 can be transferred to the second chamber 74 via the flow path 115. The processing container 72 containing the second chamber 74 is connected to a flow path 116, through which the working medium diluted with permeated water in the second chamber 74 is discharged outside the system, i.e., vented. Furthermore, a high concentration of working medium is replenished to the working medium holding tank 78 via a flow path 117.

[0072] Next, the operating steps of the carbon dioxide recovery system according to the fifth embodiment will be described.

[0073] Waste gas is introduced from near the lower part of the absorption tower 50 through waste gas inlet flow path 101. When the absorbent (amine-containing water) is insufficient, it is supplied from the absorbent replenishment tank 51 through flow path 102 from near the lower part of the absorption tower 50. Furthermore, the absorbent is dispersed from a liquid disperser (not shown) at the upper part of the absorption tower 50, reacting with carbon dioxide in the rising waste gas within the absorption tower 50. Most of the absorbent is stored as a carbon dioxide-rich solution at the lower part of the absorption tower 50. The carbon dioxide-rich solution is then transported to the upper part of the regeneration tower 60 through flow path 103, which is equipped with heat exchanger 52.

[0074] The carbon dioxide desorbed gas is conveyed from the top of the absorption tower 50 through flow path 104 to the diffusion suppression section 53. The carbon dioxide desorbed gas is accompanied by a portion of the absorbent liquid. Therefore, in the diffusion suppression section 53, the absorbent liquid is washed with wash water to prevent its components from diffusing into the environment. The wash water contains the absorbent liquid components and is therefore reused as the absorbent liquid, as described later.

[0075] The carbon dioxide-rich liquid conveyed to the upper part of the regeneration tower 60 is heated by the heat of the reboiler 61, releasing carbon dioxide from the carbon dioxide-rich liquid conveyed from the flow path 103, and is used as an absorbent for regeneration. This absorbent is stored as a carbon dioxide-lean liquid in the lower part of the regeneration tower and circulated to the liquid disperser of the absorption tower 50 through the flow path 108, which is cross-connected with the heat exchanger 52, for absorbing carbon dioxide from the aforementioned waste gas. Additionally, the heat exchanger 52 heats the carbon dioxide-rich liquid flowing in the flow path 103 using the heated carbon dioxide-lean liquid flowing through the flow path 108, while simultaneously cooling the carbon dioxide-lean liquid itself. Furthermore, the carbon dioxide in the regeneration tower 60 is conveyed to the gas purification section 62 through the flow path 109, where it is purified, and then recovered to the carbon dioxide recovery section (not shown) through the flow path 110.

[0076] The wash water containing the absorbent liquid component (amine compound) in the diffusion inhibition section 53 is transported as the treated water to the wash water storage tank 76 for storage.

[0077] The treated water in the wash water storage tank 76 is introduced into the treated water tank 77, which includes a carbon dioxide introduction mechanism, through flow path 112, where carbon dioxide dissolves in the treated water. The treated water containing amine and dissolved in carbon dioxide is supplied to the first chamber 73 of the osmotic pressure generator 71, separated by a semi-permeable membrane 75, through flow path 113. Before and after the supply of treated water, a high-concentration working medium is supplied from the working medium reservoir 78 to the second chamber 74 through flow path 115. At this time, the concentration of the working medium supplied to the second chamber 74 is higher than the concentration of amine in the treated water supplied to the first chamber 73, resulting in a higher ion molar concentration. Therefore, an osmotic pressure difference is generated between the treated water in the first chamber 73 and the working medium in the second chamber 74, causing water in the treated water to move through the semi-permeable membrane 75 towards the working medium side in the second chamber 74. Through this movement of permeated water, the treated water in the first chamber 73 is concentrated and circulated back to the treated water tank 77 through flow path 114. On the other hand, the working medium in chamber 2 74 is diluted by the moving permeate water and discharged to the outside through flow path 116. In addition, when the capacity of the working medium in the working medium holding tank 78 decreases, a high concentration of working medium is replenished to the working medium holding tank 78 through flow path 117.

[0078] Using amine-containing wash water stored in wash water storage tank 76 as treated water, carbon dioxide is introduced into the treated water in treated water tank 77, which includes a carbon dioxide introduction mechanism. This treated water is then supplied to osmotic pressure generator 71 to concentrate the amine. In this process, as described in the first embodiment, the treated water circulating from the first chamber 73 of osmotic pressure generator 71 to wash water storage tank 76 has a lower content of water and unused amine compounds compared to the treated water before it was introduced into the first chamber 73, but the content of useful amine compounds is maintained. That is, the treated water in the first chamber 73 can be returned to the treated water tank 77 in a concentrated state by relatively increasing the content of useful amine compounds. The concentrated water, in which the useful amine compounds in the treated water are sufficiently concentrated and circulated between the treated water tank 77, which includes the carbon dioxide introduction mechanism, and the osmotic pressure generator 71, can be returned from the treated water tank 77 to wash water storage tank 76 through flow path 121. The concentrated wash water in the wash water storage tank 76 can be transferred to the absorbent replenishment tank 51 via the amine-containing water concentration system 70, and can be reused as absorbent.

[0079] Therefore, according to the fifth embodiment, by conveying the carbon dioxide desorbed gas, along with a portion of the absorbent liquid, from the top of the absorption tower 50 to the diffusion suppression section 53, where the absorbent liquid component (amine) is washed with water, and by draining this washing water, it is concentrated and circulated between the treated water tank 77 (containing a carbon dioxide introduction mechanism) and the osmotic pressure generator 71 without being discharged outside the system, thereby enabling the absorption liquid to be reused as waste gas from the absorption tower 50. As a result, the wastewater treatment equipment containing amine washing water can be omitted, and the absorbent liquid can be reused, thus providing a highly economical carbon dioxide recovery system.

[0080] Furthermore, the fifth embodiment is not limited to returning the concentrated treated water from the treated water tank 77 to the wash water storage tank 76 and then transferring it from the wash water storage tank 76 to the absorbent replenishment tank 51. For example, the concentrated treated water can be directly transferred from the treated water tank 77 to the absorbent replenishment tank 51. Since it does not mix with the unconcentrated wash water in the wash water storage tank 76, concentrated water containing a higher concentration of amines can be supplied to the absorbent replenishment tank 51. Alternatively, the concentrated treated water can be transferred from the wash water storage tank 76 to a liquid disperser (not shown) at the top of the absorption tower 50 or to the top of the regeneration tower 60 for absorbent reuse.

[0081] In the fifth embodiment, similar to the second embodiment, a pump may be installed on the flow path 113 connecting the treated water tank 77 (including the carbon dioxide introduction mechanism) and the first chamber 73 of the osmotic pressure generator 71. Alternatively, similar to the third embodiment, a filter may be installed on the flow path 112 connecting the wash water storage tank 76 and the treated water tank 77. The pump is preferably set to a maximum ejection pressure of 1 MPa or less.

[0082] (Sixth Embodiment)

[0083] Reference Figure 6 The carbon dioxide recovery system according to the sixth embodiment will be described in detail.

[0084] Figure 6 This is a simplified diagram illustrating the carbon dioxide recovery system according to the sixth embodiment. Additionally, Figure 6 In the context of the fifth embodiment, Figure 5 For the same components, use the same symbols and omit the descriptions.

[0085] Figure 6 The carbon dioxide recovery system 40 according to the sixth embodiment shown includes a working medium regeneration device 79 instead of a working medium container 78. The working medium regeneration device 79 is connected to the second chamber 74 of the osmotic pressure generator 71 via a flow path 115. Furthermore, the second chamber 74 is also connected to the working medium regeneration device 79 via a flow path 116. That is, a working medium circulation system is formed where the working medium flows through the working medium regeneration device 79, flow path 115, second chamber 74, and flow path 116, and then returns to the working medium regeneration device 79.

[0086] Similar to the regeneration device described in the fourth embodiment, the working medium regeneration device 79 circulates the diluted working medium by moving water from the treated water in the first chamber 73 through the semi-permeable membrane 75, and regenerates a high-concentration working medium by separating the water from the diluted working medium. Most of the water generated during this separation process is supplied to the wash water storage tank 76 via flow path 119 for use as wash water. Additionally, a portion of the water generated in the working medium regeneration device 79 is discharged outside the system via flow path 120. The working medium regeneration device 79, for example, has a configuration that removes water from the diluted working medium using membrane distillation or similar methods to regenerate a high-concentration working medium.

[0087] According to this sixth embodiment, the working medium is supplied from the working medium regeneration device 79 to the second chamber 74 via flow path 115 in the working medium circulation system. Water from the treated water in the first chamber 73 permeates through the semi-permeable membrane 75, and the working medium diluted with this water is conveyed to the working medium regeneration device 79 via flow path 116, where a high-concentration working medium is regenerated by removing water. The regenerated working medium is then circulated back to the second chamber 74 via flow path 115 for reuse.

[0088] Therefore, similar to the fifth embodiment, the wastewater treatment equipment containing amine can be omitted, and the wastewater can be reused as an absorbent. In addition, by reducing the amount of working medium used and the amount of waste, a low-cost carbon dioxide recovery system 40 can be achieved.

[0089] Several embodiments of the present invention have been described, but these embodiments are given by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, modifications, and combinations can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the invention described in the claims and its equivalents.

[0090] Furthermore, the above-described implementation methods can be summarized into the following technical solutions.

[0091] [Technical Solution 1]

[0092] An amine-containing water concentration system is used to concentrate water containing amines, wherein the system comprises:

[0093] An osmotic pressure generator includes a treatment container, a first chamber disposed within the treatment container for supplying the water to be treated, a second chamber for containing a working medium, and a semi-permeable membrane for separating the first and second chambers; and

[0094] A carbon dioxide introduction mechanism that can introduce carbon dioxide into the water being treated.

[0095] [Technical Solution 2]

[0096] According to the concentration system of technical solution 1, it further includes a pump for supplying the treated water to the first chamber, the maximum ejection pressure of the pump being less than 1 MPa.

[0097] [Technical Solution 3]

[0098] According to the concentration system of technical solution 1 or 2, a filtration unit is further provided in the flow path that supplies the treated water to the first chamber.

[0099] [Technical Solution 4]

[0100] According to any one of technical solutions 1 to 3, the concentration system wherein the working medium contains at least one selected from inorganic salts, amine compounds, sugars, polarity-conversion compounds, and compounds having a minimum critical dissolution temperature.

[0101] [Technical Solution 5]

[0102] According to any one of technical solutions 1 to 4, in the concentration system, the osmotic pressure of the concentrated water obtained in the first chamber is 800 mOsm or higher.

[0103] [Technical Solution 6]

[0104] A carbon dioxide recovery system comprising a concentration system as described in any one of technical solutions 1 to 5.

[0105] [Technical Solution 7]

[0106] The carbon dioxide recovery system according to technical solution 6 further includes an absorbent supply tank, an absorption tower, and a regeneration tower.

[0107] [Technical Solution 8]

[0108] According to the carbon dioxide recovery system of technical solution 7, the concentrated water obtained by the amine-containing water concentration system is supplied to at least one selected from the absorbent supply tank, the absorption tower and the regeneration tower.

[0109] [Technical Solution 9]

[0110] An amine-containing water concentration device, comprising:

[0111] An osmotic pressure generator includes a treatment container, a first chamber disposed within the treatment container for supplying water to be treated, a second chamber for containing a working medium, and a semi-permeable membrane for separating the first and second chambers; and

[0112] A carbon dioxide introduction mechanism that can introduce carbon dioxide into the water being treated.

Claims

1. An amine-containing water concentration system, which is a system for concentrating amine-containing water to be treated, wherein, have: An osmotic pressure generator includes a treatment container, and a first chamber disposed within the treatment container for supplying the water to be treated, a second chamber for containing a working medium, and a semi-permeable membrane for separating the first and second chambers; and A carbon dioxide introduction mechanism that can introduce carbon dioxide into the water being treated; The working medium induces positive osmotic pressure. The amine comprises a first amine compound and a second amine compound, the first amine compound reacting with carbon dioxide in the treated water after the carbon dioxide has been introduced, and the second amine compound not reacting with carbon dioxide in the treated water after the carbon dioxide has been introduced. In the treated water in which the carbon dioxide has been introduced, the first amine compound reacts with the carbon dioxide to become a cation with bicarbonate as an anti-ion, or it becomes a carbamate by addition to carbon dioxide and carries a charge. The second amine compound is less likely to carry a charge than the first amine compound. In the treated water in which the carbon dioxide has been introduced, the second amine compound permeates the semipermeable membrane more readily than the first amine compound.

2. The concentration system according to claim 1, wherein, It further includes a pump for supplying the treated water to the first chamber, the pump having a maximum ejection pressure of 1 MPa or less.

3. The concentration system according to claim 1 or 2, wherein, The flow path that supplies the treated water to the first chamber further includes a filtration unit.

4. The concentration system according to claim 1 or 2, wherein, The working medium contains at least one of the following: inorganic salts, amine compounds, sugars, polarity-reversing compounds, and compounds having a minimum critical dissolution temperature.

5. The concentration system according to claim 1 or 2, wherein, The concentrated water obtained in the first chamber has an osmotic pressure of over 800 mOsm.

6. A carbon dioxide recovery system comprising a concentration system according to any one of claims 1 to 5.

7. The carbon dioxide recovery system according to claim 6, wherein, It further includes an absorbent replenishment tank, an absorption tower, and a regeneration tower.

8. The carbon dioxide recovery system according to claim 7, wherein, The concentrated water obtained through the amine-containing water concentration system is supplied to at least one of the absorbent supply tank, the absorbent tower, and the regeneration tower.

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