Dehydration concentration device, and carbon dioxide recovery facility

Abstract

To provide a dehydration concentration device which can suppress energy required for enhancing concentration of an organic compound.SOLUTION: A dehydration concentration device 25 dehydrates water from a mixture containing water and an organic compound, and enhances concentration of the organic compound, in which the organic compound is a water-soluble organic compound that has a boiling point of 100°C or higher at 1 atm and does not form an azeotropic mixture with water, includes a high temperature side cell 61 to which a mixture having a temperature set at lower than 100°C is introduced, a hydrophobic porous membrane 63 arranged so as to be capable of releasing water vapor from the high temperature side cell 61, and a low temperature side cell 62 that is arranged so as to sandwich the hydrophobic porous membrane 63 and face the high temperature side cell 61 at a prescribed interval from the hydrophobic porous membrane 63, and to which a coolant set at a temperature lower than the mixture is introduced.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a dehydration concentration device that dehydrates water from a mixture containing water and an organic compound to increase the concentration of the organic compound, and a carbon dioxide recovery facility including the dehydration concentration device.

Background Art

[0002] As a method for recovering carbon dioxide, for example, a chemical absorption method using reaction absorption with an alkaline compound is known. In the chemical absorption method, a gas containing carbon dioxide and an amine-based absorption liquid are brought into contact in an absorption tower, and the absorption liquid that has absorbed carbon dioxide is sent from the absorption tower to a regeneration tower, and carbon dioxide is released from the absorption liquid in the regeneration tower and recovered (see, for example, Patent Document 1). Here, as the carbon dioxide absorption liquid, for example, one obtained by adding a diluent (organic compound) to an amine-based compound is used.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the carbon dioxide separation and recovery method using the carbon dioxide absorption liquid as described above, when carbon dioxide is absorbed in the absorption tower and carbon dioxide is released in the regeneration tower repeatedly, the organic compound in the absorption liquid is released, and the gas containing the released organic compound is discharged from the absorption tower and the regeneration tower. By bringing water into contact with the discharged gas to generate a mixture containing water and an organic compound, the organic compound can be separated and recovered. However, when the organic compound is reused, it is necessary to concentrate the organic compound.

[0005] Conventionally, as a method for concentrating organic compounds, generally, a distillation method utilizing the boiling point difference of each component of a mixture has been carried out. However, in the distillation method, in order to concentrate the organic compound, it is necessary to heat and boil it up to 100 °C, which is the boiling point of water, for dehydration, requiring a large amount of energy. Also, in order to concentrate the organic compound to the desired purity, large-scale distillation equipment is required.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide a dehydration concentration apparatus and a carbon dioxide recovery facility capable of suppressing the energy required to increase the concentration of an organic compound.

Means for Solving the Problems

[0007] The characteristic configuration of the dehydration concentration apparatus according to the present invention for solving the above problems is a dehydration concentration apparatus that dehydrates water from a mixture containing water and an organic compound to increase the concentration of the organic compound, wherein the organic compound is a water-soluble organic compound having a boiling point of 100 °C or higher at 1 atm and not forming an azeotropic mixture with water, a high-temperature side cell into which the mixture set at a temperature lower than 100 °C is introduced, a hydrophobic porous membrane disposed so as to be able to release water vapor from the high-temperature side cell, a low-temperature side cell that is disposed facing the high-temperature side cell with a predetermined interval from the hydrophobic porous membrane across the hydrophobic porous membrane and into which a refrigerant set at a temperature lower than the mixture is introduced, and comprising the above.

[0008] According to the dehydration and concentration device of this configuration, a mixture containing water and an organic compound and set at a temperature of less than 100°C is introduced into the high-temperature side cell, and the water vapor that has passed through the hydrophobic porous membrane, which has the property of allowing gas to pass through but not liquid, moves to the low-temperature side cell driven by the pressure difference of the water vapor pressure, is cooled and condensed, and is taken out of the system as permeated water. Here, in the mixture, since the organic compound is a water-soluble organic compound that does not form an azeotrope with water, water can be selectively passed through the hydrophobic porous membrane as water vapor from the mixture, and the organic compound can remain in the mixture. In this way, since the mixture can be dehydrated without boiling, the energy required to increase the concentration of the organic compound can be suppressed compared to the conventional distillation method.

[0009] In the dehydration and concentration device according to the present invention, It is preferable to provide a pressure reducing means for reducing the pressure in the space formed between the hydrophobic porous membrane and the low-temperature side cell.

[0010] According to the dehydration and concentration device of this configuration, since the space formed between the hydrophobic porous membrane and the low-temperature side cell is reduced in pressure by the pressure reducing means, the water permeation flux of the water vapor passing through the hydrophobic porous membrane can be increased, and the organic compound can be concentrated with high efficiency.

[0011] In the dehydration and concentration device according to the present invention, It is preferable to provide a condenser for condensing the water vapor released from the hydrophobic porous membrane on the surface of the low-temperature side cell facing the high-temperature side cell.

[0012] According to the dehydration and concentration device of this configuration, the water vapor that has passed through the hydrophobic porous membrane, been released, and moved to the low-temperature side cell can be condensed by the condenser and efficiently taken out of the system as permeated water, so the pressure difference between the high-temperature side cell and the low-temperature side cell can be maintained at a high level. Thereby, the water permeation flux of the water vapor passing through the hydrophobic porous membrane can be increased, and the organic compound can be concentrated with high efficiency.

[0013] In the dehydration and concentration device according to the present invention, The hydrophobic porous membrane is preferably composed of at least one resin selected from the group consisting of polysulfone, polyethersulfone, polyethylene, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, and polychlorotrifluoroethylene.

[0014] According to the dehydration concentration apparatus of this configuration, by using the resin selected from the above group, a large number of pores are formed. For example, in an operation in the normal atmospheric pressure to vacuum range, water does not penetrate into the porous membrane and a space is maintained inside, so that water on the membrane surface cannot penetrate into the porous membrane, but water vapor can permeate through the porous membrane, and a hydrophobic porous membrane can be obtained.

[0015] In the dehydration concentration apparatus according to the present invention, The organic compound is preferably at least one selected from the group consisting of dimethyl sulfoxide, hexamethylphosphoric triamide, 1,3-dimethyl-2-imidazolidinone, N,N'-dimethylpropyleneurea, tetramethylurea, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylformamide, N-methylacetamide, N-methyl-2-pyrrolidone, sulfolane, monoethanolamine, diethanolamine, dipropanolamine, N-methylethanolamine, N-ethylethanolamine, N-butylethanolamine, N-propylethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, and N-butyldiethanolamine.

[0016] According to the dehydration concentration apparatus of this configuration, by using the organic compound selected from the above group, a water azeotrope is not formed, and water can be selectively passed through the hydrophobic porous membrane as water vapor from the mixture, and the organic compound can be left in the mixture.

[0017] In the dehydration concentration apparatus according to the present invention, It is preferable that the difference between the temperature of the mixture introduced into the high-temperature side cell and the temperature of the refrigerant introduced into the low-temperature side cell is set to 10 °C or more.

[0018] The movement of water vapor from the high-temperature side cell to the low-temperature side cell occurs with the pressure difference between the high-temperature side cell and the low-temperature side cell as the driving force. Therefore, by making the pressure in the high-temperature side cell high, that is, the temperature high, and the pressure in the low-temperature side low, that is, the temperature low, the driving force due to the pressure difference can be ensured. According to the dehydration concentration apparatus of this configuration, since the difference between the temperature of the mixture introduced into the high-temperature side cell and the temperature of the refrigerant introduced into the low-temperature side cell is set to 10 °C or more, a sufficient driving force for moving water vapor from the high-temperature side cell to the low-temperature side cell can be ensured.

[0019] In the dehydration concentration apparatus according to the present invention, It is preferable that the temperature of the mixture introduced into the high-temperature side cell is set to 45 to 90 °C.

[0020] According to the dehydration concentration apparatus of this configuration, since the temperature of the mixture introduced into the high-temperature side cell is set to 45 to 90 °C, the pressure required in the high-temperature side cell can be ensured.

[0021] In the dehydration concentration apparatus according to the present invention, It is preferable that the temperature of the refrigerant introduced into the low-temperature side cell is set to 0 to 80 °C.

[0022] According to the dehydration concentration apparatus of this configuration, since the temperature of the refrigerant introduced into the low-temperature side cell is set to 0 to 80 °C, the pressure required in the low-temperature side cell can be ensured.

[0023] Next, the characteristic configuration of the carbon dioxide recovery facility according to the present invention for solving the above problems is A carbon dioxide recovery facility that recovers carbon dioxide contained in a carbon dioxide-containing gas, An absorption tower that absorbs the carbon dioxide into an absorption liquid containing a water-soluble organic compound having a boiling point of 100 °C or higher at 1 atm and not forming an azeotropic mixture with water A regeneration tower that releases the carbon dioxide from the absorption liquid that has absorbed the carbon dioxide, a mixture generation unit that contacts water with a gas containing the organic compound released from the absorption liquid, which is discharged from the absorption tower and / or the regeneration tower, to generate a mixture containing the water and the organic compound, a dehydration concentration device that dehydrates water from the mixture and increases the concentration of the organic compound, and is provided with The dehydration concentration device includes a high-temperature side cell into which the mixture set at a temperature of less than 100°C is introduced, a hydrophobic porous membrane disposed so as to be able to release water vapor from the high-temperature side cell, a low-temperature side cell that is disposed opposite to the high-temperature side cell with a predetermined interval from the hydrophobic porous membrane interposed therebetween and into which a refrigerant set at a temperature lower than that of the mixture is introduced, and is provided with.

[0024] According to the carbon dioxide recovery facility of this configuration, even if an organic compound is released by repeating the absorption / dissipation of carbon dioxide with respect to the absorption liquid, the concentration of the organic compound in the mixture can be increased by the dehydration concentration device with lower energy compared to the distillation method and can be reused, so that the running cost can be reduced.

Brief Description of the Drawings

[0025]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0026] Hereinafter, the present invention will be described with reference to the drawings. However, the present invention is not intended to be limited to the embodiments described below or the configurations described in the drawings.

[0027] <Overall Configuration> FIG. 1 is a block diagram showing the overall configuration of a combustion facility 1 to which a carbon dioxide recovery facility 20 equipped with a dehydration and concentration apparatus 25 of the present invention is applied. In FIG. 1, the combustion facility 1 includes a combustion furnace 2, an exhaust gas treatment facility 10, and a carbon dioxide recovery facility 20.

[0028] <Combustion Furnace> The combustion furnace 2 burns combustibles such as waste such as municipal waste and biomass fuel, for example. As long as the combustibles can be burned, the type of the furnace is not limited, and examples include a stoker-type combustion furnace and a fluidized-bed combustion furnace.

[0029] <Exhaust Gas Treatment Facility> The exhaust gas treatment facility 10 treats the exhaust gas (corresponding to the "carbon dioxide-containing gas" of the present invention) generated by the combustion in the combustion furnace 2, and includes a boiler 3, a desuperheater 4, a dust collector 5, a denitration device 6, and an induced draft fan 7 arranged in order from the upstream side to the downstream side of the exhaust gas flow. In the exhaust gas treatment facility 10, the exhaust gas from the combustion furnace 2 is sequentially sent to the boiler 3, the desuperheater 4, the dust collector 5, and the denitration device 6 by the suction action of the induced draft fan 7. The exhaust gas is subjected to heat exchange in the boiler 3 and then cooled to a predetermined temperature in the desuperheater 4 before being sent to the dust collector 5. The exhaust gas from which dust has been removed by the dust collector 5 is sent to the denitration device 6. The exhaust gas that has been denitrified by the denitration device 6 is discharged to the outside of the system via the first discharge route 11 and / or the second discharge route 12.

[0030] Here, the first exhaust route 11 is a route for discharging to the outside of the system through the suction fan 7 and the chimney 8 arranged on the downstream side of the exhaust gas flow of the suction fan 7. The second exhaust route 12 is a route for discharging to the outside of the system through the branch duct 16 provided in a form branching from the duct 15 connecting the denitration device 6 and the suction fan 7 and the carbon dioxide recovery facility 20 connected to the duct 15 through the branch duct 16.

[0031] In the branch duct 16, a damper 17 and a suction fan 18 are provided in order from the upstream side to the downstream side of the exhaust gas flow. A part of the exhaust gas flowing through the duct 15 is sent to the carbon dioxide recovery facility 20 by the suction action of the suction fan 18. The damper opening degree of the damper 17 is controlled by a damper opening degree signal from a control device (not shown), and by controlling the damper opening degree, the amount of exhaust gas sent to the carbon dioxide recovery facility 20 is controlled.

[0032] The carbon dioxide recovery facility 20 recovers carbon dioxide from the exhaust gas through an absorption liquid. The carbon dioxide recovery facility 20 employs a chemical absorption method in which carbon dioxide is absorbed into the absorption liquid by reacting an alkaline compound in the absorption liquid with carbon dioxide. In the following description, as necessary, the absorption liquid with a high carbon dioxide content containing absorbed carbon dioxide is referred to as "rich liquid", and the absorption liquid with a low carbon dioxide content from which the absorbed carbon dioxide has been released is referred to as "lean liquid".

[0033] <Absorption liquid> As the absorption liquid used in the present invention, it is preferable that the absorbed carbon dioxide can be released at a relatively low temperature of 80 to 100°C. Although not particularly limited, for example, a non-aqueous carbon dioxide absorption liquid (amine liquid) disclosed in JP-A-2021-154237 can be used. The carbon dioxide absorption liquid contains a carbon dioxide chemisorbing amine having a nitrogen-hydrogen bond and a tertiary amine having no nitrogen-hydrogen bond, and further contains a diluent of an organic compound. The carbon dioxide absorption liquid is obtained by mixing a carbon dioxide chemisorbing amine and a tertiary amine and adding a diluent. Note that the absorption liquid is not limited to a non-aqueous amine liquid, and a known aqueous amine solution diluted with a diluent or the like can be used.

[0034] <organic compound> The organic compound used as the diluent is a water-soluble organic compound having a boiling point of 100°C or higher at 1 atm and not forming an azeotropic mixture with water. Examples of the organic compound include dimethyl sulfoxide, hexamethylphosphoric triamide, 1,3-dimethyl-2-imidazolidinone, N,N'-dimethylpropyleneurea, tetramethylurea, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylformamide, N-methylacetamide, N-methyl-2-pyrrolidone, sulfolane, monoethanolamine, diethanolamine, dipropanolamine, N-methylethanolamine, N-ethylethanolamine, N-butylethanolamine, N-propylethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, and N-butyldiethanolamine. These organic compounds may be used alone or as a mixture of two or more. By using the above organic compounds, water can be selectively passed through the hydrophobic porous membrane as water vapor from the mixture without forming an azeotropic mixture with water, and the organic compounds can remain in the mixture.

[0035] <Overall configuration of carbon dioxide recovery facility> The carbon dioxide recovery facility 20 includes an absorption tower 21, a regeneration tower 22, a heat exchanger 23, heating means 24, and a dehydration concentration device 25.

[0036] <Absorption tower> The absorption tower 21 brings a lean liquid capable of absorbing carbon dioxide into contact with the exhaust gas, absorbs the carbon dioxide in the exhaust gas into the lean liquid to generate a rich liquid, and stores and stores the generated rich liquid. At the lower part of the absorption tower 21, the downstream end of the exhaust gas flow of the branch duct 16 is connected. At the top of the absorption tower 21, a first gas discharge pipe 26 for discharging the decarbonated gas (off-gas) after carbon dioxide has been recovered from the exhaust gas is connected. Inside the upper part of the absorption tower 21, a lean liquid sprayer 27 for spraying the lean liquid is provided, and an absorption tower packing material 28 for enhancing the efficiency of gas-liquid contact is provided in the middle part between the lean liquid sprayer 27 and the lower part of the absorption tower 21.

[0037] <Regeneration tower> The regeneration tower 22 dissipates carbon dioxide from the rich liquid supplied from the absorption tower 21, regenerates the rich liquid into a lean liquid. At the top of the regeneration tower 22, a second gas discharge pipe 29 for discharging the recovered CO2-containing gas containing the recovered carbon dioxide and the like is connected. Inside the upper part of the regeneration tower 22, a rich liquid sprayer 30 for spraying the rich liquid is provided, and a regeneration tower packing material 31 for enhancing the efficiency of gas-liquid contact is provided in the middle part between the rich liquid sprayer 30 and the lower part of the regeneration tower 22.

[0038] In the middle of the first gas discharge pipe 26, a first mixture generation unit 35 is interposed. The first mixture generation unit 35 is configured to separate the organic compound from the off-gas by bringing water into contact with the off-gas containing the organic compound dissipated from the absorption liquid in the absorption tower 21. The first mixture generation unit 35 and the dehydration concentration device 25 (mixture tank 51 described later) are connected by a first mixture supply pipe 36, and the mixture containing water and the organic compound generated in the first mixture generation unit 35 is supplied to the dehydration concentration device 25 via the first mixture supply pipe 36.

[0039] In the middle of the second gas discharge pipe 29, a second mixture generation unit 37 is provided. The second mixture generation unit 37 is configured to separate organic compounds from the recovered CO2-containing gas by bringing water into contact with the recovered CO2-containing gas containing organic compounds dissipated from the absorption liquid in the regeneration tower 22. The second mixture generation unit 37 and the dehydration concentration device 25 (mixture tank 51 described later) are connected by a second mixture supply pipe 38, and the mixture containing water and organic compounds generated in the second mixture generation unit 37 is supplied to the dehydration concentration device 25 via the second mixture supply pipe 38.

[0040] The bottom of the absorption tower 21 and the rich liquid sprayer 30 are connected by a rich liquid supply pipe 41. A rich liquid pumping pump (not shown) is provided in the rich liquid supply pipe 41. The rich liquid that has absorbed carbon dioxide in the absorption tower 21 is pumped from the bottom of the absorption tower 21 to the rich liquid sprayer 30 via the rich liquid supply pipe 41 by the operation of the rich liquid pumping pump, and is supplied into the regeneration tower 22 through the rich liquid sprayer 30.

[0041] <lean liquid supply pipe> The bottom of the regeneration tower 22 and the lean liquid sprayer 27 are connected by a lean liquid supply pipe 42. A lean liquid pumping pump (not shown) is provided in the lean liquid supply pipe 42. The lean liquid that has been regenerated in the regeneration tower 22 and dissipated carbon dioxide is pumped from the bottom of the regeneration tower 22 to the lean liquid sprayer 27 via the lean liquid supply pipe 42 by the operation of the lean liquid pumping pump, and is supplied into the absorption tower 21 through the lean liquid sprayer 27.

[0042] <heat exchanger> The rich liquid supply pipe 41 and the lean liquid supply pipe 42 are arranged in a form that intersects via a heat exchanger 23. The heat exchanger 23 is of a type that performs heat exchange between the rich liquid flowing through the rich liquid supply pipe 41 and the lean liquid flowing through the lean liquid supply pipe 42. Note that there may be cases where heat exchange (heating, cooling) is not performed between the rich liquid and the lean liquid, and in this case, the heat exchanger 23 is omitted.

[0043] <heating means> The heating means 24 includes a reboiler 45. The reboiler 45 is installed in the middle of a reflux pipe 46 which is connected to the lower part of the regeneration tower 22 in a form branched from a lean liquid supply pipe 42, for refluxing a part of the regenerated absorbent withdrawn from the regeneration tower 22 to the regeneration tower 22. Steam generated, for example, by using heat recovered from exhaust gas by a boiler is introduced into and withdrawn from the reboiler 45 so that the absorbent can be heated using the steam as a heat source. In the heating means 24, the absorbent that has absorbed the heat of the steam by heat exchange between the absorbent introduced into the reboiler 45 through the reflux pipe 46 and the steam introduced into the reboiler 45 is refluxed into the regeneration tower 22 through the reflux pipe 46, thereby heating the absorbent inside the regeneration tower 22. Note that the heat source for heating the absorbent is not limited to the above-described steam. For example, the reboiler 45 may be connected so that the dedusted exhaust gas sent out from the exhaust gas treatment facility 10 can be introduced into and withdrawn from the reboiler 45, and the absorbent may be heated using the exhaust heat of the exhaust gas.

[0044] In the carbon dioxide recovery facility 20, in the absorption tower 21, the exhaust gas supplied into the tower through the branch duct 16 rises inside the absorption tower 21, and the lean liquid supplied from the lean liquid sprayer 27 descends inside the absorption tower 21. In this process, the exhaust gas and the lean liquid come into countercurrent contact. On the surface of the absorption tower packing 28, the lean liquid flows down, and the flowing-down lean liquid and the exhaust gas rising inside the absorption tower 21 come into gas-liquid contact. In the absorption tower 21, the lean liquid absorbs carbon dioxide to become a rich liquid with a high carbon dioxide content, and the rich liquid is stored at the bottom of the tower. On the other hand, the off-gas after carbon dioxide is recovered from the exhaust gas rises toward the top of the absorption tower 21. This off-gas is discharged out of the system after the organic compounds are separated by contact with water in the process of passing through the first mixture generation unit 35 through the first gas discharge pipe 26 from the top of the absorption tower 21.

[0045] The rich liquid stored at the bottom of the absorption tower 21 is supplied to the rich liquid atomizer 30 in the regeneration tower 22 via the rich liquid supply pipe 41. At this time, the rich liquid is heated by heat exchange with the lean liquid from the regeneration tower 22 in the heat exchanger 23. Thereby, the carbon dioxide recovery efficiency can be further improved.

[0046] In the regeneration tower 22, the rich liquid supplied from the rich liquid atomizer 30 descends inside the regeneration tower 22 and is stored at the bottom of the tower, and the stored absorption liquid (a mixture of rich liquid and lean liquid) is heated by the reboiler 45. Thereby, carbon dioxide gas is dissipated from the absorption liquid, and carbon dioxide gas is separated from the absorption liquid.

[0047] The recovered CO₂-containing gas containing the carbon dioxide gas separated from the absorption liquid and the vapor component of the diluent (organic compound) of the absorption liquid rises inside the regeneration tower 22. In the process of this recovered CO₂-containing gas passing through the second mixture generation unit 37 from the top of the regeneration tower 22 via the second gas discharge pipe 29, the organic compound is separated by contact with water, and it becomes a carbon dioxide-based gas, and for example, it is supplied to a carbon dioxide storage facility (not shown) and stored once, and then supplied to a carbon dioxide demand destination as needed.

[0048] A part of the absorption liquid withdrawn from the bottom of the regeneration tower 22 is withdrawn via the lean liquid supply pipe 42 and the reflux pipe 46 and introduced into the reboiler 45, and after being heated by the reboiler 45, it is introduced into the regeneration tower 22. On the other hand, the remainder of the absorption liquid withdrawn from the bottom of the regeneration tower 22 is supplied as lean liquid to the lean liquid atomizer 27 in the absorption tower 21 via the lean liquid supply pipe 42. At this time, the lean liquid is cooled by heat exchange with the rich liquid from the absorption tower 21 in the heat exchanger 23. Thereby, an absorption liquid that can more easily absorb carbon dioxide can be obtained.

[0049] Figure 2 is a block diagram showing the schematic configuration of the dehydration and concentration device 25 of the present invention. As shown in Figure 2, the dehydration and concentration device 25 includes a membrane distillation unit 50 that dehydrates water from a mixture, a mixture tank 51 that stores the mixture, and a refrigerant tank 52 that stores a refrigerant.

[0050] <Membrane distillation unit> The membrane distillation unit 50 mainly includes a high-temperature side cell 61, a low-temperature side cell 62, a hydrophobic porous membrane 63, and a condenser 64.

[0051] <High-temperature side cell> The high-temperature side cell 61 is configured such that the mixture introduced from one side flows to the other side. One side of the high-temperature side cell 61 and the mixture tank 51 are connected by a mixture forward pipe 65. A mixture pump 66 is provided in the middle of the mixture forward pipe 65. The other side of the high-temperature side cell 61 and the mixture tank 51 are connected by a mixture return pipe 67. In the present embodiment, by the operation of the mixture pump 66, the mixture stored in the mixture tank 51 is pumped into the high-temperature side cell 61 through the mixture forward pipe 65, flows from one side to the other side of the high-temperature side cell 61, and is refluxed to the mixture tank 51 through the mixture return pipe 67.

[0052] <Low-temperature side cell> The low-temperature side cell 62 is configured such that the mixture introduced from the other side flows to one side. The other side of the low-temperature side cell 62 and the refrigerant tank 52 are connected by a refrigerant forward pipe 68. A refrigerant pump 69 is provided in the middle of the refrigerant forward pipe 68. One side of the low-temperature side cell 62 and the refrigerant tank 52 are connected by a refrigerant return pipe 70. In the present embodiment, by the operation of the refrigerant pump 69, the refrigerant stored in the refrigerant tank 52 is pumped into the low-temperature side cell 62 through the refrigerant forward pipe 68, flows from the other side to one side of the low-temperature side cell 62, and is refluxed to the refrigerant tank 52 through the refrigerant return pipe 70. The refrigerant is not particularly limited, and examples include water and air. In the present embodiment, water is used as the refrigerant.

[0053] <Hydrophobic porous membrane> The hydrophobic porous membrane 63 is arranged so as to be able to release water vapor from the high-temperature side cell 61. The hydrophobic porous membrane 63 is made of resin. The resin is not particularly limited, and examples thereof include polysulfone, polyethersulfone, polyethylene, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, and polychlorotrifluoroethylene. These resins may be used alone or as a mixture of two or more.

[0054] The low-temperature side cell 62 faces the high-temperature side cell 61 with a predetermined interval from the hydrophobic porous membrane 63 with the hydrophobic porous membrane 63 interposed therebetween, and the flow direction of the refrigerant in the low-temperature side cell 62 is opposite to the flow direction of the mixture in the high-temperature side cell 61. In this example, an example where the flow direction of the mixture in the high-temperature side cell 61 and the flow direction of the refrigerant in the low-temperature side cell 62 are in a counterflow in opposite directions is shown, but it is not limited thereto, and the flow direction of the mixture in the high-temperature side cell 61 and the flow direction of the refrigerant in the low-temperature side cell 62 may be in a parallel flow in the same direction.

[0055] The condenser 64 is provided on the surface of the low-temperature side cell 62 facing the high-temperature side cell 61 so as to be able to condense the water vapor released from the hydrophobic porous membrane 63. The condenser 64 is mainly composed of a plate-like body such as a metal with high thermal conductivity. The size of the gap (distance T) between the condenser 64 and the hydrophobic porous membrane 63 is preferably set to 0.5 to 5 mm, and more preferably set to 0.7 to 5 mm.

[0056] The space (S) formed between the hydrophobic porous membrane 63 and the low-temperature side cell 62 (condenser 64) is adjusted by a vacuum pump 71 that functions as a pressure reducing means to be in a vacuum state or a pressure lower than atmospheric pressure.

[0057] The mixture tank 51 is connected to the first mixture generation unit 35 (see FIG. 1) via the first mixture supply pipe 36 and is also connected to the second mixture generation unit 37 (see FIG. 1) via the second mixture supply pipe 38. Thus, the mixture containing water and the organic compound generated in the first mixture generation unit 35 is supplied to the mixture tank 51 via the first mixture supply pipe 36, and the mixture containing water and the organic compound generated in the second mixture generation unit 37 is supplied to the mixture tank 51 via the second mixture supply pipe 38. Further, the mixture tank 51 is connected via a concentrated mixture supply pipe 72 to a portion between the regeneration tower 22 and the heat exchanger 23 in the lean liquid supply pipe 42 (see FIG. 1).

[0058] The mixture tank 51 is provided with a heater 73 for heating the mixture stored in the mixture tank 51. In the present embodiment, the heating of the mixture by the heater 73 is adjusted so that the temperature of the mixture introduced into the high-temperature side cell 61 is 45 to 90°C. Thereby, the water vapor pressure required in the high-temperature side cell 61 can be ensured. The refrigerant tank 52 is provided with a cooler 74 for cooling the refrigerant stored in the refrigerant tank 52. In the present embodiment, the cooling of the refrigerant by the cooler 74 is adjusted so that the temperature of the refrigerant introduced into the low-temperature side cell 62 is 0 to 80°C. Thereby, the water vapor pressure required in the low-temperature side cell 62 can be ensured.

[0059] In the dehydration concentration device 25, it is preferable that the difference between the temperature of the mixture introduced into the high-temperature side cell 61 and the temperature of the refrigerant introduced into the low-temperature side cell 62 is set to 10°C or more. Thereby, a sufficient driving force for moving water vapor from the high-temperature side cell 61 to the low-temperature side cell 62 can be ensured.

[0060] In the dehydration concentration device 25 configured as described above, the mixture adjusted to a predetermined temperature (45 to 90°C) below 100°C by the heater 73 is introduced from the mixture tank 51 into the high-temperature side cell 61 through the mixture forward pipe 65 by the operation of the mixture pump 66, flows from one side to the other side of the high-temperature side cell 61, and is refluxed to the mixture tank 51 through the mixture return pipe 67. Thus, the mixture is circulated in the circulation path 80 that leads from the mixture tank 51 through the mixture forward pipe 65, the high-temperature side cell 61, and the mixture return pipe 67 to the mixture tank 51.

[0061] As the mixture is introduced into the high-temperature side cell 61 and flows from one side to the other side, the water vapor that has passed through the hydrophobic porous membrane 63 moves to the low-temperature side cell 62 using the pressure difference in water vapor pressure between the high-temperature side cell 61 and the low-temperature side cell 62 as the driving force, and is condensed by the condenser 64 and taken out as permeated water. Since the organic compound contained in the mixture is a water-soluble organic compound that does not form an azeotropic mixture with water, water can be selectively passed through the hydrophobic porous membrane 63 as water vapor from the mixture, and the organic compound can be left in the mixture. Thus, since the mixture can be dehydrated without boiling, the energy required to increase the concentration of the organic compound can be suppressed compared to the distillation method of dehydrating by heating to 100°C, the boiling point of water, and boiling.

[0062] In the dehydration concentration device 25, the space (S) formed between the hydrophobic porous membrane 63 and the low-temperature side cell 62 is decompressed by the decompression pump 71, which can increase the water permeation flux of the water vapor passing through the hydrophobic porous membrane 63 and can concentrate the organic compound with high efficiency. Also, since the water vapor that has passed through the hydrophobic porous membrane 63 and is released and moves to the low-temperature side cell 62 can be efficiently condensed by the condenser 64 and taken out of the system as permeated water, the pressure difference in water vapor pressure between the high-temperature side cell 61 and the low-temperature side cell 62 can be maintained at a high level. Thereby, the water permeation flux of the water vapor passing through the hydrophobic porous membrane 63 can be increased, and the organic compound can be concentrated with high efficiency.

[0063] The mixture is concentrated to a reusable concentration in the carbon dioxide recovery facility 20 by circulating it in the circulation path 80 for a predetermined time (reusable if it is 20 to 30 wt%). Then, the concentrated mixture is supplied from the mixture tank 51 to the absorption tower 21 via the concentrated mixture supply pipe 72 and the lean liquid supply pipe 42. Thereby, the organic compound in the concentrated mixture can be reused as a diluent for the absorbent liquid.

[0064] As described above, the dehydration concentration apparatus and the carbon dioxide recovery facility of the present invention have been described based on one embodiment. However, the present invention is not limited to the configuration described in the above embodiment, and the configuration can be appropriately changed without departing from the gist thereof.

Example

[0065] Hereinafter, an example of the dehydration concentration apparatus of the present invention will be described. However, the present invention is not limited to these examples.

[0066] An experiment was conducted on the influence of the DMSO (dimethyl sulfoxide) concentration in the mixture on the water permeation flux and the amount of DMSO flowing out into the permeate under the experimental conditions shown in Table 1.

[0067]

Table 1

[0068] Figure 3 is a graph showing the relationship between the water permeation flux and the DMSO concentration in the permeate with respect to the DMSO concentration in the mixture. As shown in Figure 3, as the DMSO concentration of the supplied mixture increases, the permeation flux decreases. This is presumably because the amount of water decreases and the pressure drops as the DMSO concentration increases. Also, as the DMSO concentration of the supplied mixture increases, the DMSO concentration in the permeate increases. However, until the DMSO concentration of the supplied mixture reaches about 50 wt%, the DMSO concentration in the permeate is 1 wt% or less. Therefore, concentration is possible until the DMSO concentration reaches about 50 wt%. When used as a diluent for a carbon dioxide absorbent, it is considered that there are no practical problems even at 30 wt% or less, more specifically, at 20 - 30 wt%.

Industrial Applicability

[0069] The dehydration concentration apparatus of the present invention can be used for dehydrating water from a mixture containing water and an organic compound to increase the concentration of the organic compound, and is particularly suitable for reuse as a diluent for a carbon dioxide absorbent.

Explanation of Reference Numerals

[0070] 20 Carbon dioxide recovery facility 25 Dehydration concentration apparatus 61 High-temperature side cell 62 Low-temperature side cell 63 Hydrophobic porous membrane 64 Condenser 71 Vacuum pump (vacuum means)

Claims

1. A dehydration concentration device for dehydrating water from a mixture containing water and an organic compound to increase the concentration of the organic compound, comprising: The organic compound is a water-soluble organic compound having a boiling point of 100°C or higher at 1 atmosphere and not forming an azeotropic mixture with water; A high-temperature side cell into which the mixture set at a temperature lower than 100°C is introduced; A hydrophobic porous membrane disposed so as to be able to release water vapor from the high-temperature side cell; A low-temperature side cell disposed facing the high-temperature side cell with a predetermined interval from the hydrophobic porous membrane across the hydrophobic porous membrane, into which a refrigerant set at a temperature lower than the mixture is introduced; A dehydration concentration device comprising the above.

2. The dehydration concentration device according to claim 1, further comprising a pressure reducing means for reducing the pressure in the space formed between the hydrophobic porous membrane and the low-temperature side cell.

3. The dehydration concentration device according to claim 1 or 2, wherein a condenser for condensing water vapor released from the hydrophobic porous membrane is provided on the surface of the low-temperature side cell facing the high-temperature side cell.

4. The dehydration concentration device according to claim 1 or 2, wherein the hydrophobic porous membrane is composed of at least one resin selected from the group consisting of polysulfone, polyethersulfone, polyethylene, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, and polychlorotrifluoroethylene.

5. The organic compound is at least one selected from the group consisting of dimethyl sulfoxide, hexamethylphosphoric triamide, 1,3-dimethyl-2-imidazolidinone, N,N'-dimethylpropyleneurea, tetramethylurea, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylformamide, N-methylacetamide, N-methyl-2-pyrrolidone, sulfolane, monoethanolamine, diethanolamine, dipropanolamine, N-methylethanolamine, N-ethylethanolamine, N-butylethanolamine, N-propylethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, and N-butyldiethanolamine. The dehydration concentration device according to claim 1 or 2.

6. The dehydration concentration device according to claim 1 or 2, wherein the difference between the temperature of the mixture introduced into the high-temperature side cell and the temperature of the refrigerant introduced into the low-temperature side cell is set to 10°C or higher.

7. The dehydration and concentration device according to claim 1 or 2, wherein the temperature of the mixture introduced into the high-temperature side cell is set to 45 to 90 °C.

8. The dehydration and concentration device according to claim 1 or 2, wherein the temperature of the refrigerant introduced into the low-temperature side cell is set to 0 to 80 °C.

9. A carbon dioxide recovery facility for recovering carbon dioxide contained in a carbon dioxide-containing gas, An absorption tower for absorbing the carbon dioxide in an absorbent liquid containing a water-soluble organic compound having a boiling point of 100 °C or higher at 1 atm and not forming an azeotropic mixture with water, A regeneration tower for releasing the carbon dioxide from the absorbent liquid that has absorbed the carbon dioxide, A mixture generation unit that brings water into contact with a gas containing the organic compound released from the absorbent liquid and discharged from the absorption tower and / or the regeneration tower to generate a mixture containing the water and the organic compound, A dehydration and concentration device for dehydrating water from the mixture and increasing the concentration of the organic compound, Comprising The dehydration and concentration device is A high-temperature side cell into which the mixture set at a temperature of less than 100 °C is introduced, A hydrophobic porous membrane arranged to be able to release water vapor from the high-temperature side cell, A low-temperature side cell that is arranged to face the high-temperature side cell with a predetermined interval from the hydrophobic porous membrane across the hydrophobic porous membrane and into which a refrigerant set at a temperature lower than that of the mixture is introduced, A carbon dioxide recovery facility comprising.

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