Carbon dioxide separation and capture system and carbon dioxide separation and capture method

Abstract

This carbon dioxide separation and recovery system comprises: an adsorption module in which a first liquid phase region and a first gas phase region are divided by a plurality of first hollow fiber membranes; a desorption module in which a second liquid phase region and a second gas phase region are divided by a plurality of second hollow fiber membranes; a liquid supply device that communicates with the first liquid phase region; a target gas supply device that communicates with the first gas phase region; a liquid communication path that is connected to the adsorption module and the desorption module and that communicates between first liquid phase region and the second liquid phase region; and a gas recovery path that communicates with the second gas phase region. Each of the plurality of first hollow fiber membranes and each of the plurality of second hollow fiber membranes comprises a dense layer that is not porous, and a porous layer positioned on the inside of the dense layer that is porous.

Description

[Technical field]

[0001] One aspect of the present invention relates to a carbon dioxide separation and capture system and a carbon dioxide separation and capture method for separating and capturing carbon dioxide. [Background technology]

[0002] In recent years, there has been a strong demand for carbon neutrality, which means reducing greenhouse gas emissions to zero overall. To achieve carbon neutrality, technology to separate and capture carbon dioxide is necessary.

[0003] Patent Document 1 describes an apparatus and method for carbon dioxide conversion aimed at establishing a human environment on Mars. The apparatus includes a first gas-liquid contactor-separator (scrubber), an electrochemical conversion cell (cell stack), and a second gas-liquid contactor-separator (stripper). The scrubber includes a hollow fiber bundle, and separates carbon dioxide from a supply gas and adsorbs the separated carbon dioxide into an ionic liquid. The cell stack includes an anode, a cathode, and an ionic membrane, and electrolyzes the ionic liquid that has adsorbed carbon dioxide to produce oxygen (O2), carbon monoxide (CO), and hydrogen (H2). The cell stack also releases the generated oxygen (O2), and reacts the generated carbon monoxide (CO) with hydrogen (H2) to produce methane (CH4) and water (H2O), and discharges the ionic liquid containing methane (CH4) and water (H2O). The stripper is equipped with a hollow fiber bundle and separates methane (CH4) from the ionic liquid discharged from the cell stack and stores the separated methane (CH4).

[0004] Non-Patent Document 1 describes a carbon dioxide adsorption / desorption test by a membrane vacuum regeneration (MVR) process using a polypropylene hollow fiber membrane contactor (PP-HFMC). This adsorption / desorption test includes an adsorption PP-HFMC and a desorption PP-HFMC. The adsorption PP-HFMC includes PP-HFMC, and adsorbs carbon dioxide in a feed gas mixture into an ionic liquid. The desorption PP-HFMC includes PP-HFMC, and desorbs carbon dioxide from the ionic liquid that has adsorbed carbon dioxide. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2003-038904 A [Non-patent literature]

[0006] [Non-Patent Document 1] Jose Manuel Vadillo, Lucia Gomez-Coma, Aurora Garea and Angel Irabien, “CO2 Desorption Performance from Imidazolium Ionic Liquids by Membrane Vacuum Regeneration Technology”, Membranes 2020, 10,234 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the techniques described in Patent Document 1 and Non-Patent Document 1 have a problem in that the hollow fiber membrane becomes wet upon contact with the ionic liquid, resulting in an early decrease in gas exchange capacity.

[0008] Therefore, an object of one aspect of the present invention is to provide a carbon dioxide separation and capture system and a carbon dioxide separation and capture method that can suppress early deterioration of gas exchange ability and enable long-term use. [Means for solving the problem]

[0009] [1] A carbon dioxide separation and capture system according to one aspect of the present invention comprises an adsorption module in which a first liquid phase region and a first gas phase region are separated by a plurality of first hollow fiber membranes for adsorbing carbon dioxide contained in a target gas into a carbon dioxide adsorbable liquid capable of adsorbing carbon dioxide; a desorption module in which a second liquid phase region and a second gas phase region are separated by a plurality of second hollow fiber membranes for desorbing carbon dioxide from the carbon dioxide adsorbable liquid; a liquid supply device connected to the first liquid phase region for supplying the carbon dioxide adsorbable liquid to the first liquid phase region; a target gas supply device connected to the first gas phase region for supplying the target gas to the first gas phase region; a liquid communication passage connected to the adsorption module and the desorption module and communicating the first liquid phase region and the second liquid phase region; and a gas recovery passage connected to the second gas phase region,

[0010] In this carbon dioxide separation and capture system, when the carbon dioxide adsorbable liquid is supplied from the liquid supply device to the first liquid phase region and the target gas is supplied from the target gas supply device to the first gas phase region, the carbon dioxide contained in the target gas permeates each of the multiple first hollow fiber membranes in the adsorption module and is adsorbed by the carbon dioxide adsorbable liquid. This makes it possible to separate carbon dioxide from the target gas and adsorb it into the carbon dioxide adsorbable liquid. The carbon dioxide adsorbable liquid with carbon dioxide adsorbed in the adsorption module is supplied to the second liquid phase region of the desorption module through a liquid communication passage. In the desorption module, carbon dioxide is desorbed from the carbon dioxide adsorbable liquid supplied to the second liquid phase region and the carbon dioxide permeates each of the multiple second hollow fiber membranes. Then, the carbon dioxide that has permeated each of the multiple second hollow fiber membranes is recovered through a gas recovery passage connected to the second gas phase region. This makes it possible to recover carbon dioxide from the carbon dioxide adsorbable liquid.

[0011] By the way, each of the first hollow fiber membranes of the adsorption module and each of the second hollow fiber membranes of the desorption module are in an environment where they are easily wetted because they come into contact with the carbon dioxide adsorbable liquid. However, each of the first hollow fiber membranes and each of the second hollow fiber membranes have a dense layer that has no porosity and a porous layer that is located inside the dense layer and has porosity. In other words, since the dense layer has no porosity, it has a structure in which the carbon dioxide adsorbable liquid is difficult to penetrate and is difficult to wet. Therefore, it is possible to suppress early deterioration of gas exchange ability. In addition, since the dense layer has no porosity, it is possible to suppress the generation of bubbles in the first liquid phase region and the second liquid phase region due to the gas passing through each of the first hollow fiber membranes and each of the second hollow fiber membranes. As a result, the range of choices for the carbon dioxide adsorbable liquid is widened, so that the optimal carbon dioxide adsorbable liquid can be selected according to the operating conditions, required performance, etc. of the carbon dioxide separation and capture system.

[0012] Furthermore, in order to improve the gas exchange capacity, it is preferable to make the dense layer, which does not have a porosity, thin, but making the dense layer thin reduces the strength of the dense layer. However, since the dense layer can be supported from the inside by the porous layer, it is possible to suppress the strength of each of the multiple first hollow fiber membranes and each of the multiple second hollow fiber membranes from decreasing due to the thinning of the dense layer. This makes it possible to suppress the strength of each of the multiple first hollow fiber membranes and each of the multiple second hollow fiber membranes from decreasing while improving the gas exchange capacity by making the dense layer thin.

[0013] [2] In the carbon dioxide separation and capture system described in [1] above, the carbon dioxide adsorbable liquid may be an ionic liquid. In this carbon dioxide separation and capture system, since the carbon dioxide adsorbable liquid is an ionic liquid, the carbon dioxide that has permeated each of the multiple first hollow fiber membranes can be appropriately adsorbed into the carbon dioxide adsorbable liquid in the adsorption module, and the carbon dioxide can be appropriately desorbed from the carbon dioxide adsorbable liquid and permeated through each of the multiple second hollow fiber membranes in the desorption module.

[0014] [3] In the carbon dioxide separation and capture system described in [1] above, the carbon dioxide adsorbable liquid may be a deep eutectic solvent. In this carbon dioxide separation and capture system, since the carbon dioxide adsorbable liquid is a deep eutectic solvent, the carbon dioxide that has permeated each of the multiple first hollow fiber membranes can be appropriately adsorbed into the carbon dioxide adsorbable liquid in the adsorption module, and the carbon dioxide can be appropriately desorbed from the carbon dioxide adsorbable liquid and permeated through each of the multiple second hollow fiber membranes in the desorption module.

[0015] [4] In the carbon dioxide separation and capture system according to any one of the above [1] to [3], the dense layer may not have pores through which the carbon dioxide adsorbable liquid can pass. In this carbon dioxide separation and capture system, since the dense layer does not have pores through which the carbon dioxide adsorbable liquid can pass, wetting of each of the plurality of first hollow fiber membranes and each of the plurality of second hollow fiber membranes can be further suppressed.

[0016] [5] In the carbon dioxide separation and capture system according to any one of [1] to [4] above, the dense layer may not have pores with a pore size of 0.01 μm or more. In this carbon dioxide separation and capture system, since the dense layer does not have pores with a pore size of 0.01 μm or more, it is possible to prevent the carbon dioxide adsorbable liquid from passing through each of the first hollow fiber membranes and each of the second hollow fiber membranes. This makes it possible to further prevent each of the first hollow fiber membranes and each of the second hollow fiber membranes from becoming wet.

[0017] [6] In the carbon dioxide separation and capture system according to any one of [1] to [5] above, the dense layer may be formed on the outer surface of each of the first hollow fiber membranes and each of the second hollow fiber membranes. In this carbon dioxide separation and capture system, the dense layer is formed on the outer surface of each of the first hollow fiber membranes and each of the second hollow fiber membranes, making it easy to form the dense layer. Moreover, when the adsorption module and the desorption module are external perfusion type modules, each of the first hollow fiber membranes and each of the second hollow fiber membranes are less likely to become wetted with a carbon dioxide adsorbing liquid, so that the gas exchange capacity can be maintained for a longer period of time.

[0018] [7] In the carbon dioxide separation and capture system according to any one of [1] to [6] above, the porosity of the porous layer may be 5% or more and 60% or less. In this carbon dioxide separation and capture system, since the porosity of the porous layer is 5% or more, it is possible to ensure a membrane area and enhance the gas exchange capacity. Meanwhile, since the porosity of the porous layer is 60% or less, it is possible to ensure a sufficient support force of the dense layer by the porous layer. In addition, since the carbon dioxide adsorbable liquid is less likely to enter the porous layer and the porous layer is less likely to become wet, it is possible to suppress an early decrease in gas exchange capacity.

[0019] [8] In the carbon dioxide separation and capture system according to any one of [1] to [7] above, the separation factor of carbon dioxide with respect to nitrogen of each of the plurality of first hollow fiber membranes and each of the plurality of second hollow fiber membranes may be 2 or more and 20 or less. In this carbon dioxide separation and capture system, since each of the plurality of first hollow fiber membranes and each of the plurality of second hollow fiber membranes has a dense layer, the separation factor of carbon dioxide with respect to nitrogen of each of the plurality of first hollow fiber membranes and each of the plurality of second hollow fiber membranes can be set to 2 or more. Since the separation factor of carbon dioxide with respect to nitrogen of each of the plurality of first hollow fiber membranes and each of the plurality of second hollow fiber membranes is 2 or more, it is possible to suppress permeation of nitrogen accompanying carbon dioxide from the first gas phase region and the second gas phase region to the first liquid phase region and the second liquid phase region. This improves the separation and capture performance of carbon dioxide. Meanwhile, since the separation factor of carbon dioxide with respect to nitrogen of each of the plurality of first hollow fiber membranes and each of the plurality of second hollow fiber membranes is 20 or less, each of the plurality of first hollow fiber membranes and each of the plurality of second hollow fiber membranes can be easily manufactured.

[0020] [9] In the carbon dioxide separation and capture system according to any one of [1] to [8] above, the first liquid phase region may be a region located outside each of the plurality of first hollow fiber membranes, and the second liquid phase region may be a region located outside each of the plurality of second hollow fiber membranes. In this carbon dioxide separation and capture system, the first liquid phase region is a region located outside each of the plurality of first hollow fiber membranes, and the second liquid phase region is a region located outside each of the plurality of second hollow fiber membranes, so that the adsorption module and the desorption module are external perfusion type modules. This makes it difficult for the porous layer to become wetted with the carbon dioxide adsorbable liquid, so that the gas exchange capacity can be maintained for a longer period of time. In addition, the pressure loss of the carbon dioxide adsorbable liquid flowing through the adsorption module and the desorption module can be reduced.

[0021]

[10] The carbon dioxide separation and capture system according to any one of [1] to [9] above may further include an aspirator provided in the gas recovery path to reduce the pressure in the second gas phase region. In this carbon dioxide separation and capture system, the aspirator provided in the gas recovery path can reduce the pressure in the second gas phase region, so that the carbon dioxide adsorbed in the carbon dioxide adsorbable liquid in the desorption module is more likely to permeate each of the multiple second hollow fiber membranes. This makes it easier to desorb carbon dioxide from the carbon dioxide adsorbable liquid, and therefore easier to capture carbon dioxide from the gas recovery path.

[0022]

[11] In the carbon dioxide separation and capture system according to any one of [1] to

[10] above, the target gas supply device may have a compressor for compressing the target gas and supplying it to the first gas phase region. In this carbon dioxide separation and capture system, since the target gas supply device has a compressor for compressing the target gas and supplying it to the first gas phase region, in the adsorption module, the carbon dioxide contained in the target gas is more likely to permeate each of the multiple first hollow fiber membranes. This makes it easier to separate carbon dioxide from the target gas and adsorb it in the carbon dioxide adsorbable liquid.

[0023]

[12] In the carbon dioxide separation and capture system according to any one of [1] to

[11] above, the adsorption module may have a first housing that accommodates a plurality of first hollow fiber membranes to form a first liquid phase region and a first gas phase region, and the first housing may have a first liquid supply port that opens the first liquid phase region to supply the carbon dioxide adsorbable liquid supplied from the liquid supply device to the first liquid phase region, a first liquid outlet port that opens the first liquid phase region to discharge the carbon dioxide adsorbable liquid supplied to the first liquid phase region from the first liquid phase region to the liquid communication channel, a first gas supply port that opens the first gas phase region to supply the target gas supplied from the target gas supply device to the first gas phase region, and a first gas outlet port that opens the first gas phase region to discharge the target gas supplied to the first gas phase region from the first gas phase region. In this carbon dioxide separation and capture system, the adsorption module has a first housing that accommodates a plurality of first hollow fiber membranes to form the first liquid phase region and the first gas phase region, so that the first liquid phase region and the first gas phase region are formed in the first housing. Since the first housing has a first liquid supply port and a first liquid discharge port, the carbon dioxide adsorbable liquid supplied from the liquid supply device can be supplied to the first liquid phase region, and the carbon dioxide adsorbable liquid supplied to the first liquid phase region can be discharged from the first liquid phase region to the liquid communication passage. Furthermore, since the first housing has a first gas supply port and a first gas discharge port, the target gas supplied from the target gas supply device can be supplied to the first gas phase region, and the target gas supplied to the first gas phase region can be discharged from the first gas phase region. This makes it possible to continue supplying the carbon dioxide adsorbable liquid and the target gas to the first liquid phase region and the first gas phase region, so that carbon dioxide can be separated from the target gas and adsorbed into the carbon dioxide adsorbable liquid over a long period of time.

[0024]

[13] In the carbon dioxide separation and capture system according to any one of [1] to

[12] above, the desorption module may have a second housing that accommodates a plurality of second hollow fiber membranes to form a second liquid phase region and a second gas phase region, and the second housing may have a second liquid supply port that opens the second liquid phase region to supply the carbon dioxide adsorbable liquid from the liquid communication passage to the second liquid phase region, a second liquid outlet that opens the second liquid phase region to discharge the carbon dioxide adsorbable liquid supplied to the second liquid phase region from the second liquid phase region, and a second gas outlet that opens the second gas phase region to discharge carbon dioxide from the second gas phase region. In this carbon dioxide separation and capture system, the desorption module has a second housing that accommodates a plurality of second hollow fiber membranes to form the second liquid phase region and the second gas phase region, and therefore the second liquid phase region and the second gas phase region are formed in the second housing. And because the second housing has a second liquid supply port and a second liquid discharge port, the carbon dioxide adsorbable liquid supplied from the adsorption module through the liquid communication passage can be supplied to the second liquid phase region, and the carbon dioxide adsorbable liquid supplied to the second liquid phase region can be discharged from the second liquid phase region. Also, because the second housing has a second gas discharge port, carbon dioxide can be discharged and recovered from the second gas phase region. This makes it possible to continue supplying the carbon dioxide adsorbable liquid to the second liquid phase region and continuing to recover carbon dioxide from the second gas phase region, so that carbon dioxide can be desorbed and recovered from the carbon dioxide adsorbable liquid over a long period of time.

[0025]

[14] In the carbon dioxide separation and capture system according to any one of [1] to

[13] above, each of the first hollow fiber membranes and each of the second hollow fiber membranes may contain an olefin resin. In this carbon dioxide separation and capture system, each of the first hollow fiber membranes and each of the second hollow fiber membranes contain an olefin resin, so that each of the first hollow fiber membranes and each of the second hollow fiber membranes can be given high hydrophobicity. As a result, in each of the first hollow fiber membranes and each of the second hollow fiber membranes, the carbon dioxide adsorbable liquid is less likely to penetrate into the porous layer, and the porous layer is less likely to become wet. Incidentally, since the dense layer does not have porosity, it has a structure that is less likely to be penetrated and wetted by the carbon dioxide adsorbable liquid, but the structure of the dense layer may collapse due to deterioration over time. However, even if the above-mentioned structure of the dense layer collapses due to deterioration over time, the high hydrophobicity of each of the multiple first hollow fiber membranes and each of the multiple second hollow fiber membranes makes it difficult for carbon dioxide adsorbing liquid to penetrate into the dense layer, making the dense layer less likely to become wet.

[0026]

[15] A carbon dioxide separation and capture method according to one aspect of the present invention is a carbon dioxide separation and capture method using any one of the carbon dioxide separation and capture systems described above, which supplies a carbon dioxide adsorbable liquid to a first liquid phase region from a liquid supply device, supplies a target gas to the first gas phase region from a target gas supply device, and captures carbon dioxide from the second gas phase region by depressurizing the second gas phase region. In this carbon dioxide separation and capture method, in the carbon dioxide separation and capture system described above, a carbon dioxide adsorbable liquid is supplied to the first liquid phase region from a liquid supply device, a target gas is supplied to the first gas phase region from a target gas supply device, and carbon dioxide is captured from the second gas phase region by depressurizing the second gas phase region, so that early deterioration of gas exchange ability can be suppressed. Effect of the Invention

[0027] According to one aspect of the present invention, it is possible to suppress an early decrease in gas exchange ability. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 is a schematic diagram of a carbon dioxide separation and capture system according to an embodiment. [Diagram 2] FIG. 2 is a schematic cross-sectional view showing an enlarged portion of the inside of the suction module. [Diagram 3] 4 is a schematic cross-sectional view showing an enlarged view of a part of the inside of the first housing. FIG. [Figure 4] FIG. 3 is an enlarged schematic cross-sectional view of a portion IV shown in FIG. 2. [Diagram 5] 4 is a schematic cross-sectional view showing an enlarged portion of the inside of the detachable module. FIG. [Figure 6] 4 is a schematic cross-sectional view showing an enlarged portion of the inside of the second housing. FIG. [Figure 7] FIG. 6 is an enlarged schematic cross-sectional view of a portion VII shown in FIG. 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Hereinafter, a degassing module and a liquid degassing method according to an embodiment will be described with reference to the drawings. In all the drawings, the same or corresponding parts are denoted by the same reference numerals, and duplicated explanations will be omitted.

[0030] Fig. 1 is a schematic diagram of a carbon dioxide separation and capture system according to an embodiment. The carbon dioxide separation and capture system 1 shown in Fig. 1 is a system for separating and capturing carbon dioxide from a target gas TG by adsorption and desorption of carbon dioxide (CO2) into a carbon dioxide adsorbable liquid CL. The carbon dioxide separation and capture system 1 includes a liquid supply device 2, a target gas supply device 3, an adsorption module 4, a desorption module 5, a liquid communication path 6, a gas recovery path 7, a suction device 8, and a liquid circulation path 9.

[0031] The liquid supply device 2 is a device for supplying the carbon dioxide adsorbable liquid CL capable of adsorbing carbon dioxide to the adsorption module 4. The carbon dioxide adsorbable liquid CL is a salt whose molecule is designed to be liquid at room temperature. Any liquid may be used as the carbon dioxide adsorbable liquid CL as long as it can adsorb and desorb carbon dioxide.

[0032] As the carbon dioxide adsorbing liquid CL, for example, an ionic liquid can be used. Ionic liquids are salts whose molecules are designed to be liquid at room temperature. Examples of the ionic liquid used as the carbon dioxide adsorbing liquid CL include ionic liquids containing a cation selected from ammonium cations, imidazolium cations, and phosphonium cations, and an anion selected from a fluorine-containing anion, a cyano group-containing anion, and an anion derived from an amino acid. Specifically, for example, an ionic liquid that combines an ammonium cation with a fluorine-containing anion (e.g., [N 1114 ][TFSA], [choline][TFSA], etc.); ionic liquids combining imidazolium cations and fluorine-containing anions (e.g., [emim][TFSA], [emim][TfO], [emim][BF4], [bmim][TFSA], [bmim][Tf3C], [bmim][TfO], [bmim][BF4], [bmim][PF6], [bmim][TFA], [hmim][TFSA], [omim][TFSA], [C6H4F9mim][TFSA], etc.); ionic liquids combining imidazolium cations and cyano-containing anions (e.g., [emim][DCA], [emim][C(CN)3], [emim][B(CN)4], [bmim][DCA], [bmim][C(CN)3], [bmim][B(CN)4], etc.); ionic liquids combining phosphonium cations and amino acid-derived anions (e.g., [P 4444 ][Pro], [P 2225 ][Pro], [P 2225 [Gly], etc. These ionic liquids may be used alone or in combination of two or more. In addition, solvents and additives other than the ionic liquid may be added to the extent that the function is not impaired.

[0033] In addition, as the carbon dioxide adsorbing liquid CL, for example, a deep eutectic solvent (DES), which is a compound exhibiting properties similar to those of an ionic liquid, can be used. A deep eutectic solvent is a compound obtained by mixing a hydrogen bond donor compound and a hydrogen bond acceptor compound, and is a compound that becomes liquid at room temperature like an ionic liquid. As the deep eutectic solvent used as the carbon dioxide adsorbing liquid CL, for example, a hydrogen bond donor can be selected from amide-based, carboxylic acid-based, and alcohol-based compounds, and a hydrogen bond acceptor can be selected from ammonium salts and phosphonium salts. Specifically, for example, a deep eutectic solvent obtained by mixing choline chloride and urea, or a mixture of choline chloride and ethylene glycol can be used.

[0034] The liquid supply device 2 has, for example, a pump 21 that pumps out the carbon dioxide adsorbable liquid CL, and the carbon dioxide adsorbable liquid CL can be supplied to the adsorption module 4 by operating this pump 21.

[0035] The liquid supply device 2 is connected to the adsorption module 4 via a liquid supply path 11. The liquid supply path 11 is formed of a tubular member such as a pipe. The liquid supply device 2 is connected to the liquid supply path 11 and thereby communicates with the liquid supply path 11, and the liquid supply path 11 is connected to the adsorption module 4 and thereby communicates with the adsorption module 4. For this reason, the carbon dioxide adsorbable liquid CL sent out from the liquid supply device 2 is supplied to the adsorption module 4 through the liquid supply path 11.

[0036] The target gas supplying device 3 is a device for supplying the target gas TG containing carbon dioxide to the adsorption module 4. Any gas containing carbon dioxide may be used as the target gas TG. Examples of the target gas TG that can be used include exhaust gas from power plants such as thermal power plants and biomass power plants, exhaust gas from cement plants, exhaust gas from steel mills, exhaust gas from factories such as oil refineries and chemical plants, exhaust gas from facilities related to hydrogen production and ammonia production, and natural gas. The target gas supplying device 3 has, for example, a compressor 31 that compresses and sends out the target gas TG, and the operation of this compressor 31 makes it possible to compress the target gas TG and supply it to the adsorption module 4.

[0037] The target gas supply device 3 is connected to the adsorption module 4 via a gas supply path 12. The gas supply path 12 is formed of a tubular member such as a pipe. The target gas supply device 3 is connected to the gas supply path 12 and thereby communicates with the gas supply path 12, and the gas supply path 12 is connected to the adsorption module 4 and thereby communicates with the adsorption module 4. Therefore, the target gas TG sent out from the target gas supply device 3 is supplied to the adsorption module 4 through the gas supply path 12.

[0038] The adsorption module 4 is a module for separating carbon dioxide contained in the target gas TG from the target gas TG and adsorbing it into the carbon dioxide adsorbable liquid CL. Fig. 2 is a schematic cross-sectional view showing an enlarged portion of the inside of the adsorption module. As shown in Figs. 1 and 2, the adsorption module 4 includes a plurality of first hollow fiber membranes 41 and a first housing 42.

[0039] Each of the first hollow fiber membranes 41 is a hollow fiber membrane that is permeable to gases such as carbon dioxide but not to liquids such as the carbon dioxide adsorbable liquid CL. Examples of the material of each of the first hollow fiber membranes 41 include polyolefin resins such as polypropylene, polyethylene, and polymethylpentene (PMP, also known as 4-methylpentene-1 and poly(4-methylpentene-1)), silicon resins such as polydimethylsiloxane and copolymers thereof, and fluorine resins such as PTFE and vinylidene fluoride.

[0040] The outer diameter of each of the first hollow fiber membranes 41 is not particularly limited, but may be, for example, 100 μm to 3000 μm, 100 μm to 500 μm, or 100 μm to 300 μm. The inner diameter of each of the first hollow fiber membranes 41 is not particularly limited, but may be, for example, 10 μm to 500 μm, 50 μm to 300 μm, or 80 μm to 200 μm. The membrane thickness of each of the first hollow fiber membranes 41 is not particularly limited, but may be, for example, 5 μm to 200 μm, 10 μm to 100 μm, or 20 μm to 50 μm.

[0041] 3 is a schematic cross-sectional view showing an enlarged portion of the inside of the first housing. As shown in FIGS. 1 to 3, the first housing 42 accommodates a plurality of first hollow fiber membranes 41. The region inside the first housing 42 is divided into a first liquid phase region L1 and a first gas phase region G1 by the plurality of first hollow fiber membranes 41. In other words, the first housing 42 forms the first liquid phase region L1 and the first gas phase region G1 which are divided by the plurality of first hollow fiber membranes 41.

[0042] The first liquid phase region L1 is a region through which the carbon dioxide adsorbable liquid CL flows, and the first gas phase region G1 is a region through which the target gas TG flows. The adsorption module 4 can be used as either an internal perfusion type or an external perfusion type module. When the adsorption module 4 is used as an external perfusion type module, the outer region 43 located on the outside (outer surface side) of each of the first hollow fiber membranes 41 becomes the first liquid phase region L1, and the inner region 44 located on the inside (inner surface side) of each of the first hollow fiber membranes 41 becomes the first gas phase region G1. That is, the region between each of the first hollow fiber membranes 41 and the first housing 42 becomes the first liquid phase region L1. On the other hand, when the adsorption module 4 is used as an internal perfusion type module, the inner region 44 located on the inside (inner surface side) of each of the first hollow fiber membranes 41 becomes the first liquid phase region L1, and the outer region 43 located on the outside (outer surface side) of each of the first hollow fiber membranes 41 becomes the first gas phase region G1. In other words, the region between each of the plurality of first hollow fiber membranes 41 and the first housing 42 becomes a first gas phase region G1.

[0043] The first housing 42 has a first liquid supply port 45, a first liquid exhaust port 46, a first gas supply port 47, and a first gas exhaust port 48.

[0044] The first liquid supply port 45 is an opening that opens the first liquid phase region L1 to supply the carbon dioxide adsorbable liquid CL supplied from the liquid supply device 2 to the first liquid phase region L1. That is, the first liquid supply port 45 is an opening formed in the first housing 42 at a position adjacent to the first liquid phase region L1. The liquid supply device 2 is in communication with the first liquid phase region L1 through the first liquid supply port 45, and is able to supply the carbon dioxide adsorbable liquid CL to the first liquid phase region L1 through the first liquid supply port 45.

[0045] The first liquid discharge port 46 is an opening that opens the first liquid phase region L1 to discharge the carbon dioxide adsorbable liquid CL supplied to the first liquid phase region L1 from the first liquid phase region L1 to the liquid communication path 6. In other words, the first liquid discharge port 46 is an opening formed in the first housing 42 at a position adjacent to the first liquid phase region L1, and is different from the first liquid supply port 45. The first liquid phase region L1 is connected to the liquid communication path 6 via the first liquid discharge port 46.

[0046] The first gas supply port 47 is an opening that opens the first gas phase region G1 to supply the target gas TG supplied from the target gas supply device 3 to the first gas phase region G1. That is, the first gas supply port 47 is an opening formed in the first housing at a position adjacent to the first gas phase region G1. The target gas supply device 3 is in communication with the first gas phase region G1 through the first gas supply port 47, and is capable of supplying the target gas TG to the first gas phase region G1 through the first gas supply port 47.

[0047] The first gas exhaust port 48 is an opening that opens the first gas phase region G1 to exhaust the target gas TG supplied to the first gas phase region G1 from the first gas phase region G1. That is, the first gas exhaust port 48 is an opening formed in the first housing at a position adjacent to the first gas phase region G1, and is different from the first gas supply port 47. The first gas phase region G1 is opened to the outside of the adsorption module 4 through the first gas exhaust port 48.

[0048] A gas discharge path 13 is connected to the first gas exhaust port 48. The gas exhaust path 13 is formed of, for example, a tubular member such as a pipe. The gas exhaust path 13 is connected to the first gas exhaust port 48, thereby communicating with the first gas phase region G1. Therefore, the target gas discharged from the first gas phase region G1 is discharged to the outside of the carbon dioxide separation and capture system 1 through the gas exhaust path 13. A flow rate regulating valve 14 is attached to the gas exhaust path 13 to regulate (limit) the flow rate of the target gas TG so that the target gas TG is maintained at a high pressure in the first gas phase region G1.

[0049] Fig. 4 is a schematic cross-sectional view showing an enlarged view of a portion IV shown in Fig. 2. As shown in Fig. 4, each of the plurality of first hollow fiber membranes 41 has a dense layer 411 and a porous layer 412.

[0050] The dense layer 411 is a layer that does not have porosity, that is, a non-porous layer. A layer that does not have porosity is, for example, a layer that does not have pores through which the carbon dioxide adsorbable liquid CL can pass. In other words, the dense layer 411 may not have pores through which the carbon dioxide adsorbable liquid CL can pass. A pore through which the carbon dioxide adsorbable liquid CL can pass is, for example, a pore whose minimum pore size is larger than the molecules that constitute the carbon dioxide adsorbable liquid CL. In this case, the dense layer 411 may have pores through which the carbon dioxide adsorbable liquid CL cannot pass. In addition, a layer that does not have porosity is, for example, a layer that does not have pores with a pore size of 0.01 μm or more, 0.005 μm or more, or 0.001 μm or more. In other words, the dense layer 411 may not have pores with a pore size of 0.01 μm or more, 0.005 μm or more, or 0.001 μm or more. In addition, when the pores are not spherical, this pore size is, for example, the maximum pore size of the pores. In this case, dense layer 411 may have pores formed with a pore size of less than 0.01 μm, less than 0.005 μm, or less than 0.001 μm.

[0051] The dense layer 411 may be a layer at any position of each of the multiple first hollow fiber membranes 41, so long as it is located outside (on the outer surface side) of the porous layer 412. From the viewpoint of easily forming the dense layer 411 and making each of the multiple first hollow fiber membranes 41 less likely to become wet when the adsorption module 4 is an external perfusion type module, the dense layer 411 may be formed, for example, on the outer surface of each of the multiple first hollow fiber membranes 41. Note that when the dense layer 411 is not formed on the outer surface of each of the multiple first hollow fiber membranes 41, a layer similar to the porous layer 412, for example, may be formed on the outside (on the outer surface side) of the dense layer 411.

[0052] The porous layer 412 is a layer located inside the dense layer 411 and has porosity. The porous layer 412 also functions as a layer supporting the dense layer 411. The layer having porosity is, for example, a layer having pores through which the carbon dioxide adsorbable liquid CL can pass. The layer having porosity is, for example, a layer having pores with a pore diameter of 0.01 μm or more, 0.05 μm or more, or 0.1 μm or more. Note that when the pores are not spherical, the pore diameter is, for example, the maximum pore diameter of the pores. The porous layer 412 is formed, for example, in a sponge-like shape.

[0053] The porosity of the porous layer 412 is not particularly limited. The porosity is the ratio of pores in a target layer such as the porous layer 412. The porosity can be calculated, for example, by measuring a certain amount of weight and volume of the hollow fiber membrane and converting from the apparent density and the true density. From the viewpoint of securing the membrane area and enhancing the gas exchange capacity, the porosity of the porous layer 412 may be, for example, 5% or more, 10% or more, or 20% or more. On the other hand, from the viewpoint of sufficiently securing the support force of the dense layer 411 by the porous layer 412 and making it difficult for the carbon dioxide adsorbable liquid CL to enter the porous layer 412 and making it difficult for the porous layer 412 to become wet, the porosity of the porous layer 412 may be, for example, 60% or less, 50% or less, or 40% or less. From these viewpoints, for example, the porosity of the porous layer 412 may be, for example, 5% or more and 60% or less, 10% or more and 50% or less, or 20% or more and 40% or less.

[0054] Incidentally, one of the indices for separating carbon dioxide from the carbon dioxide adsorbable liquid CL is the separation factor α of carbon dioxide with respect to nitrogen. The separation factor α can be obtained, for example, by measuring the permeation rates of carbon dioxide and nitrogen based on ASTM D-1434, and then calculating the ratio of the permeation rate of carbon dioxide to the permeation rate of nitrogen (permeation rate of carbon dioxide / permeation rate of nitrogen). When the separation factor α of carbon dioxide with respect to nitrogen in each of the first hollow fiber membranes 41 is greater than 1, carbon dioxide can be separated from the carbon dioxide adsorbable liquid CL. The separation factor α of carbon dioxide with respect to nitrogen in each of the first hollow fiber membranes 41 is not particularly limited as long as it is greater than 1. From the viewpoint of suppressing the permeation of nitrogen from the gas phase region to the liquid phase region accompanying carbon dioxide, the separation factor α of carbon dioxide with respect to nitrogen in each of the first hollow fiber membranes 41 may be, for example, 2 or more, 8 or more, or 10 or more. On the other hand, from the viewpoint of easily manufacturing each of the multiple first hollow fiber membranes 41, the separation coefficient α of carbon dioxide relative to nitrogen in each of the multiple first hollow fiber membranes 41 may be, for example, 20 or less, 17 or less, or 15 or less. From these viewpoints, the separation coefficient α of carbon dioxide relative to nitrogen in each of the multiple first hollow fiber membranes 41 may be, for example, 2 or more and 20 or less, 8 or more and 17 or less, or 10 or more and 15 or less.

[0055] As shown in Fig. 1, the desorption module 5 is a module for desorbing and recovering carbon dioxide from the carbon dioxide adsorbable liquid CL to which carbon dioxide has been adsorbed in the adsorption module 4. Fig. 5 is a schematic cross-sectional view showing an enlarged view of a part of the inside of the desorption module. As shown in Figs. 1 and 5, the desorption module 5 includes a plurality of second hollow fiber membranes 51 and a second housing 52.

[0056] Each of the second hollow fiber membranes 51 is a hollow fiber membrane that is permeable to gases such as carbon dioxide but not to liquids such as the carbon dioxide adsorbable liquid CL, similar to each of the first hollow fiber membranes 41. Examples of the material of each of the second hollow fiber membranes 51 include polyolefin resins such as polypropylene, polyethylene, and polymethylpentene, silicon resins such as polydimethylsiloxane and copolymers thereof, and fluorine resins such as PTFE and vinylidene fluoride.

[0057] The outer diameter of each of the second hollow fiber membranes 51 is not particularly limited, but may be, for example, 100 μm to 3000 μm, 100 μm to 500 μm, or 100 μm to 300 μm. The inner diameter of each of the second hollow fiber membranes 51 is not particularly limited, but may be, for example, 10 μm to 500 μm, 50 μm to 300 μm, or 80 μm to 200 μm. The membrane thickness of each of the second hollow fiber membranes 51 is not particularly limited, but may be, for example, 5 μm to 200 μm, 10 μm to 100 μm, or 20 μm to 50 μm.

[0058] Fig. 6 is a schematic cross-sectional view showing an enlarged portion of the inside of the second housing. As shown in Figs. 1, 5 and 6, the second housing 52 accommodates a plurality of second hollow fiber membranes 51. The region inside the second housing 52 is divided into a second liquid phase region L2 and a second gas phase region G2 by the plurality of second hollow fiber membranes 51. In other words, the second housing 52 forms the second liquid phase region L2 and the second gas phase region G2 which are divided by the plurality of second hollow fiber membranes 51.

[0059] The second liquid phase region L2 is a region through which the carbon dioxide adsorbable liquid CL flows, and the second gas phase region G2 is a region through which the carbon dioxide desorbed from the carbon dioxide adsorbable liquid CL flows. The desorption module 5 can be used as either an internal perfusion type or an external perfusion type module. When the desorption module 5 is used as an external perfusion type module, the outer region 53 located on the outside (external surface side) of each of the second hollow fiber membranes 51 becomes the second liquid phase region L2, and the inner region 54 located on the inside (inner surface side) of each of the second hollow fiber membranes 51 becomes the second gas phase region G2. That is, the region between each of the second hollow fiber membranes 51 and the second housing 52 becomes the second liquid phase region L2. On the other hand, when the desorption module 5 is used as an internal perfusion type module, the inner region 54 located on the inside (inner surface side) of each of the second hollow fiber membranes 51 becomes the second liquid phase region L2, and the outer region 53 located on the outside (outer surface side) of each of the second hollow fiber membranes 51 becomes the second gas phase region G2. In other words, the region between each of the plurality of second hollow fiber membranes 51 and the second housing 52 becomes the second gas phase region G2.

[0060] The second housing 52 has a second liquid supply port 55 , a second liquid exhaust port 56 , and a second gas exhaust port 57 .

[0061] The second liquid supply port 55 is an opening that opens the second liquid phase region L2 to supply the carbon dioxide adsorbable liquid CL from the liquid communication passage 6 to the second liquid phase region L2. In other words, the second liquid supply port 55 is an opening formed in the second housing 52 at a position adjacent to the second liquid phase region L2. The liquid communication passage 6 is connected to the second liquid phase region L2 through the second liquid supply port 55.

[0062] The second liquid discharge port 56 is an opening that opens the second liquid phase region L2 to discharge the carbon dioxide adsorbable liquid CL supplied to the second liquid phase region L2 from the second liquid phase region L2 to the liquid circulation path 9. In other words, the second liquid discharge port 56 is an opening formed in the second housing 52 at a position adjacent to the second liquid phase region L2, and is different from the second liquid supply port 55. The second liquid phase region L2 is in communication with the liquid circulation path 9 through the second liquid discharge port 56.

[0063] The second gas discharge port 57 is an opening that opens the second gas phase region G2 to discharge the carbon dioxide desorbed from the carbon dioxide adsorbable liquid CL from the second liquid phase region L2. That is, the second gas discharge port 57 is an opening formed in the second housing 52 at a position adjacent to the second gas phase region G2. The second gas phase region G2 is in communication with the gas recovery path 7 through the second gas discharge port 57.

[0064] Fig. 7 is a schematic cross-sectional view showing an enlarged view of portion VII shown in Fig. 5. As shown in Fig. 7, each of the plurality of second hollow fiber membranes 51 has a dense layer 511 and a porous layer 512.

[0065] The dense layer 511, like the dense layer 411, is a layer that does not have porosity, that is, a non-porous layer. Like the dense layer 411, the dense layer 511 may not have pores through which the carbon dioxide adsorbable liquid CL can pass. Also, like the dense layer 411, the dense layer 511 may not have pores with a pore size of 0.01 μm or more, 0.005 μm or more, or 0.001 μm or more. Note that, when the pores are not spherical, this pore size is, for example, the maximum pore size of the pores. In this case, the dense layer 511 may have pores with a pore size of less than 0.01 μm, less than 0.005 μm, or less than 0.001 μm.

[0066] The dense layer 511 may be a layer at any position of each of the multiple second hollow fiber membranes 51 as long as it is located outside (on the outer surface side) of the porous layer 512. Similarly to the dense layer 411, the dense layer 511 may be formed, for example, on the outer surface of each of the multiple second hollow fiber membranes 51. If the dense layer 511 is not formed on the outer surface of each of the multiple second hollow fiber membranes 51, a layer similar to the porous layer 512, for example, may be formed on the outside (on the outer surface side) of the dense layer 511.

[0067] Similar to the porous layer 412, the porous layer 512 is a layer located inside the dense layer 511 and having porosity. The porous layer 512 also functions as a layer supporting the dense layer 5411. The porous layer 512 is formed, for example, in a sponge shape.

[0068] The porosity of the porous layer 512 is not particularly limited. From the same viewpoint as the porous layer 412, the porosity of the porous layer 512 may be, for example, 5% or more, 10% or more, or 20% or more. On the other hand, from the same viewpoint as the porous layer 412, the porosity of the porous layer 512 may be, for example, 60% or less, 50% or less, or 40% or less. From these viewpoints, the porosity of the porous layer 512 may be, for example, 5% or more and 60% or less, 10% or more and 50% or less, or 20% or more and 40% or less.

[0069] The separation factor α of carbon dioxide relative to nitrogen in each of the multiple second hollow fiber membranes 51 is not particularly limited as long as it is greater than 1. From the same viewpoint as each of the multiple first hollow fiber membranes 41, the separation factor α of carbon dioxide relative to nitrogen in each of the multiple second hollow fiber membranes 51 may be, for example, 2 or more, 8 or more, or 10 or more. On the other hand, from the same viewpoint as each of the multiple first hollow fiber membranes 41, the separation factor α of carbon dioxide relative to nitrogen in each of the multiple second hollow fiber membranes 51 may be, for example, 20 or less, 17 or less, or 15 or less. From these viewpoints, the separation factor α of carbon dioxide relative to nitrogen in each of the multiple second hollow fiber membranes 51 may be, for example, 2 or more and 20 or less, 8 or more and 17 or less, or 10 or more and 15 or less.

[0070] The liquid communication passage 6 is connected to the adsorption module 4 and the desorption module 5, and communicates between the first liquid phase region L1 of the adsorption module 4 and the second liquid phase region L2 of the desorption module 5. The liquid communication passage 6 is formed of a tubular member such as a pipe. One end of the liquid communication passage 6 is connected to the first liquid outlet 46 of the first housing 42, and thus communicates with the first liquid phase region L1. The other end of the liquid communication passage 6 is connected to the second liquid supply port 55 of the second housing 52, and thus communicates with the second liquid phase region L2. For this reason, the carbon dioxide adsorbable liquid CL discharged from the first liquid phase region L1 of the adsorption module 4 is supplied to the second liquid phase region L2 of the desorption module 5 through the liquid communication passage 6.

[0071] The gas recovery path 7 is connected to the desorption module 5 and communicates with the second gas phase region G2 of the desorption module 5. The gas recovery path 7 is formed of a tubular member such as a pipe. The gas recovery path 7 is connected to the second gas outlet 57 of the second housing 52, and thereby communicates with the second gas phase region G2. Therefore, the carbon dioxide desorbed from the carbon dioxide adsorbable liquid CL in the desorption module 5 and permeated through each of the multiple second hollow fiber membranes 51 is recovered through the gas recovery path 7.

[0072] The suction device 8 is a device provided in the gas recovery path 7 to reduce the pressure in the second gas phase region G2 of the desorption module 5 and recover carbon dioxide. The suction device 8 has, for example, a vacuum pump 81 that sends out gas, and operation of this vacuum pump 81 makes it possible to send out gas such as carbon dioxide from the desorption module 5 side to the opposite side of the desorption module 5 in the gas recovery path 7, thereby reducing the pressure in the second gas phase region G2 and recovering carbon dioxide from the second gas phase region G2.

[0073] The liquid circulation path 9 is connected to the desorption module 5 and the liquid supply device 2 in order to supply the carbon dioxide adsorbable liquid CL discharged from the desorption module 5 to the adsorption module 4. The liquid circulation path 9 is formed of a tubular member such as a pipe. One end of the liquid circulation path 9 is connected to the second liquid outlet 56 of the second housing 52, thereby communicating with the second liquid phase region L2. The other end of the liquid circulation path 9 is connected to the liquid supply device 2, thereby communicating with the liquid supply device 2. Therefore, the carbon dioxide adsorbable liquid CL discharged from the second liquid phase region L2 of the desorption module 5 is supplied to the liquid supply device 2 through the liquid circulation path 9.

[0074] Next, a carbon dioxide separation and capture method using the carbon dioxide separation and capture system 1 will be described.

[0075] In this carbon dioxide separation and recovery method, the carbon dioxide adsorbable liquid CL is supplied from the liquid supply device 2 to the first liquid phase region L1 of the adsorption module 4. That is, the pump 21 of the liquid supply device 2 is operated to supply the carbon dioxide adsorbable liquid CL to the first liquid phase region L1. In addition, the target gas TG is supplied from the target gas supply device 3 to the first gas phase region G1 of the adsorption module 4. That is, the compressor 31 of the target gas supply device 3 is operated to compress the target gas TG and supply it to the adsorption module 4. At this time, it is preferable to adjust the flow rate of the target gas TG at the first gas discharge port 48 by the flow control valve 14 so that the target gas TG is maintained in a high pressure state in the first gas phase region G1. In addition, the second gas phase region G2 of the desorption module 5 is depressurized by the suction device 8. That is, by operating the vacuum pump 81, gas is sent from the desorption module 5 side to the opposite side of the desorption module 5 in the gas recovery path 7 to depressurize the second gas phase region G2.

[0076] Then, in the adsorption module 4, the carbon dioxide contained in the target gas TG supplied to the first gas phase region G1 permeates through each of the multiple first hollow fiber membranes 41 and is adsorbed by the carbon dioxide adsorbable liquid CL supplied to the first liquid phase region L1. This separates the carbon dioxide from the target gas TG. Then, the carbon dioxide adsorbable liquid CL having adsorbed the carbon dioxide is discharged from the first liquid phase region L1 to the liquid communication passage 6. Meanwhile, the target gas TG from which the carbon dioxide has been separated is discharged from the first gas phase region G1 to the outside of the carbon dioxide separation and capture system 1 through the gas discharge path 13.

[0077] The carbon dioxide adsorbable liquid CL discharged from the first liquid phase region L1 to the liquid communication passage 6 is supplied from the liquid communication passage 6 to the second liquid phase region L2 of the desorption module 5. In the desorption module 5, since the second gas phase region G2 is depressurized by the suction device 8, the carbon dioxide adsorbed in the carbon dioxide adsorbable liquid CL supplied from the liquid communication passage 6 to the second liquid phase region L2 permeates each of the second hollow fiber membranes 51. Then, the carbon dioxide adsorbable liquid CL from which the carbon dioxide has been desorbed is discharged from the second liquid phase region L2 to the liquid circulation passage 9. Meanwhile, the carbon dioxide that has permeated each of the second hollow fiber membranes 51 is discharged from the second gas phase region G2 to the gas recovery passage 7. Then, the carbon dioxide is recovered from the second gas phase region G2 through the gas recovery passage 7.

[0078] In this manner, in the carbon dioxide separation and capture system 1 according to the present embodiment, when the carbon dioxide adsorbable liquid CL is supplied from the liquid supply device 2 to the first liquid phase region L1 and the target gas TG is supplied from the target gas supply device 3 to the first gas phase region G1, the carbon dioxide contained in the target gas TG permeates through each of the first hollow fiber membranes 41 in the adsorption module 4 and is adsorbed into the carbon dioxide adsorbable liquid CL. This allows carbon dioxide to be separated from the target gas TG and adsorbed into the carbon dioxide adsorbable liquid CL. The carbon dioxide adsorbable liquid CL to which carbon dioxide has been adsorbed in the adsorption module 4 is supplied to the second liquid phase region L2 of the desorption module 5 through the liquid communication passage 6. In the desorption module 5, carbon dioxide is desorbed from the carbon dioxide adsorbable liquid CL supplied to the second liquid phase region L2, and the carbon dioxide permeates through each of the second hollow fiber membranes 51. Then, the carbon dioxide that has permeated through each of the second hollow fiber membranes 51 is recovered through the gas recovery passage 7 connected to the second gas phase region G2. This allows carbon dioxide to be recovered from the carbon dioxide adsorbable liquid CL.

[0079] Incidentally, each of the first hollow fiber membranes 41 of the adsorption module 4 and each of the second hollow fiber membranes 51 of the desorption module 5 are in an environment where they are easily wetted because they come into contact with the carbon dioxide adsorbable liquid CL. However, each of the first hollow fiber membranes 41 has a dense layer 411 that has no porosity and a porous layer 412 that is located inside the dense layer 411 and has porosity. Also, each of the second hollow fiber membranes 51 has a dense layer 511 that has no porosity and a porous layer 512 that is located inside the dense layer 511 and has porosity. In other words, the dense layer 411 and the dense layer 511 have a structure that is difficult for the carbon dioxide adsorbable liquid CL to penetrate and to become wetted because they have no porosity. For this reason, it is possible to suppress an early decrease in gas exchange ability. Furthermore, since the dense layers 411 and 511 are not porous, it is possible to suppress the generation of bubbles in the first liquid phase region L1 and the second liquid phase region L2 caused by the gas passing through each of the multiple first hollow fiber membranes 41 and each of the multiple second hollow fiber membranes 51. As a result, the range of choices for the carbon dioxide adsorbable liquid CL is broadened, so that an optimal carbon dioxide adsorbable liquid CL can be selected depending on the operating conditions, required performance, etc. of the carbon dioxide separation and capture system 1.

[0080] Furthermore, in order to improve the gas exchange capacity, it is preferable to make the dense layers 411 and 511, which do not have porosity, thin, but making the dense layers 411 and 511 thin reduces the strength of the dense layers 411 and 511. However, since the dense layers 411 and 511 can be supported from the inside by the porous layers 412 and 512, it is possible to prevent the strength of each of the multiple first hollow fiber membranes 41 and each of the multiple second hollow fiber membranes 51 from decreasing due to the thinning of the dense layers 411 and 511. This makes it possible to prevent the strength of each of the multiple first hollow fiber membranes 41 and each of the multiple second hollow fiber membranes 51 from decreasing while improving the gas exchange capacity by making the dense layers 411 and 511 thin.

[0081] Furthermore, in this carbon dioxide separation and capture system 1, since the carbon dioxide adsorbent liquid CL is an ionic liquid, in the adsorption module 4, the carbon dioxide that has permeated each of the multiple first hollow fiber membranes 41 can be appropriately adsorbed into the carbon dioxide adsorbent liquid CL, and in the desorption module 5, the carbon dioxide can be appropriately desorbed from the carbon dioxide adsorbent liquid CL and permeated through each of the multiple second hollow fiber membranes 51.

[0082] Furthermore, in this carbon dioxide separation and capture system 1, since the carbon dioxide adsorbable liquid CL is a deep eutectic solvent, in the adsorption module 4, the carbon dioxide that has permeated each of the multiple first hollow fiber membranes 41 can be appropriately adsorbed into the carbon dioxide adsorbable liquid CL, and in the desorption module 5, the carbon dioxide can be appropriately desorbed from the carbon dioxide adsorbable liquid CL and permeated through each of the multiple second hollow fiber membranes 51.

[0083] In addition, in this carbon dioxide separation and capture system 1, since the dense layers 411 and 511 do not have pores through which the carbon dioxide adsorbing liquid CL can pass, wetting of each of the multiple first hollow fiber membranes 41 and each of the multiple second hollow fiber membranes 51 can be further suppressed.

[0084] Furthermore, in this carbon dioxide separation and capture system 1, the dense layers 411 and 511 do not have pores with a pore size of 0.01 μm or more, 0.005 μm or more, or 0.001 μm or more, and therefore it is possible to prevent the carbon dioxide adsorbable liquid CL from passing through each of the multiple first hollow fiber membranes 41 and each of the multiple second hollow fiber membranes 51. This makes it possible to further prevent each of the multiple first hollow fiber membranes 41 and each of the multiple second hollow fiber membranes 51 from getting wet.

[0085] In addition, in this carbon dioxide separation and capture system 1, the dense layers 411 and 511 are formed on the outer surfaces of each of the multiple first hollow fiber membranes 41 and each of the multiple second hollow fiber membranes 51, making it easy to form the dense layers 411 and 511. Moreover, when the adsorption module 4 and the desorption module 5 are external perfusion type modules, each of the multiple first hollow fiber membranes 41 and each of the multiple second hollow fiber membranes 51 are less likely to become wet with the carbon dioxide adsorbable liquid CL, making it possible to maintain the gas exchange capacity for a longer period of time.

[0086] In addition, in this carbon dioxide separation and capture system 1, since the porosity of the porous layer 412 and the porous layer 512 is 5% or more, 10% or more, or 20% or more, it is possible to ensure the membrane area and enhance the gas exchange capacity. Meanwhile, since the porosity of the porous layer 412 and the porous layer 512 is 60% or less, 50% or less, or 40% or less, it is possible to ensure a sufficient support force of the dense layer 411 and the dense layer 511 by the porous layer 412 and the porous layer 512. In addition, since the carbon dioxide adsorbable liquid CL is unlikely to enter the porous layer 412 and the porous layer 512, the porous layer 412 and the porous layer 512 are unlikely to become wet, it is possible to suppress an early decrease in the gas exchange capacity.

[0087] In addition, in this carbon dioxide separation and capture system 1, since each of the multiple first hollow fiber membranes 41 and each of the multiple second hollow fiber membranes 51 have a dense layer 411 and a dense layer 511, the separation coefficient α of carbon dioxide for nitrogen of each of the multiple first hollow fiber membranes 41 and each of the multiple second hollow fiber membranes 51 can be set to 2 or more. And, since the separation coefficient α of carbon dioxide for nitrogen of each of the multiple first hollow fiber membranes 41 and each of the multiple second hollow fiber membranes 51 is 2 or more, 8 or more, or 10 or more, it is possible to suppress permeation of nitrogen accompanying carbon dioxide from the first gas phase region G1 and the second gas phase region G2 to the first liquid phase region L1 and the second liquid phase region L2. This improves the separation and capture performance of carbon dioxide. Meanwhile, since the separation coefficient α of carbon dioxide for nitrogen of each of the multiple first hollow fiber membranes 41 and each of the multiple second hollow fiber membranes 51 is 20 or less, 17 or less, or 15 or less, each of the multiple first hollow fiber membranes 41 and each of the multiple second hollow fiber membranes 51 can be easily manufactured.

[0088] Furthermore, in this carbon dioxide separation and capture system 1, when the first liquid phase region L1 is a region located outside each of the multiple first hollow fiber membranes 41 and the second liquid phase region L2 is a region located outside each of the multiple second hollow fiber membranes 51, the adsorption module 4 and the desorption module 5 become external perfusion type modules. In this case, the porous layers 412 and 512 are less likely to be wetted by the carbon dioxide adsorbable liquid CL, so that the gas exchange capacity can be maintained for an even longer period of time. Also, the pressure loss of the carbon dioxide adsorbable liquid CL flowing through the adsorption module 4 and the desorption module 5 can be reduced.

[0089] In addition, in this carbon dioxide separation and capture system 1, the second gas phase region G2 can be depressurized by the suction device 8 provided in the gas recovery path 7, so that in the desorption module 5, the carbon dioxide adsorbed in the carbon dioxide adsorbable liquid CL easily permeates each of the multiple second hollow fiber membranes 51. This makes it easier to desorb carbon dioxide from the carbon dioxide adsorbable liquid CL, and therefore easier to capture carbon dioxide from the gas recovery path 7.

[0090] Furthermore, in this carbon dioxide separation and capture system 1, the target gas supply device 3 has the compressor 31 for compressing the target gas TG and supplying it to the first gas phase region G1, so that in the adsorption module 4, the carbon dioxide contained in the target gas TG easily permeates each of the multiple first hollow fiber membranes 41. This makes it easier to separate the carbon dioxide from the target gas TG and adsorb it in the carbon dioxide adsorbable liquid CL.

[0091] In addition, in this carbon dioxide separation and capture system 1, the adsorption module 4 has a first housing 42 that houses a plurality of first hollow fiber membranes 41 to form a first liquid phase region L1 and a first gas phase region G1, so that the first liquid phase region L1 and the first gas phase region G1 are formed in the first housing 42. And, since the first housing 42 has a first liquid supply port 45 and a first liquid discharge port 46, the carbon dioxide adsorbable liquid CL supplied from the liquid supply device 2 can be supplied to the first liquid phase region L1, and the carbon dioxide adsorbable liquid CL supplied to the first liquid phase region L1 can be discharged from the first liquid phase region L1 to the liquid communication passage 6. Also, since the first housing 42 has a first gas supply port 47 and a first gas discharge port 48, the target gas TG supplied from the target gas supply device 3 can be supplied to the first gas phase region G1, and the target gas TG supplied to the first gas phase region G1 can be discharged from the first gas phase region G1. This makes it possible to continue supplying the carbon dioxide adsorbable liquid CL and the target gas TG to the first liquid phase region L1 and the first gas phase region G1, thereby enabling carbon dioxide to be separated from the target gas TG and adsorbed into the carbon dioxide adsorbable liquid CL over a long period of time.

[0092] In addition, in this carbon dioxide separation and capture system 1, the desorption module 5 has a second housing 52 that houses a plurality of second hollow fiber membranes 51 to form the second liquid phase region L2 and the second gas phase region G2, so that the second liquid phase region L2 and the second gas phase region G2 are formed in the second housing 52. And, since the second housing 52 has a second liquid supply port 55 and a second liquid discharge port 56, the carbon dioxide adsorbable liquid CL supplied from the adsorption module 4 through the liquid communication passage 6 can be supplied to the second liquid phase region L2, and the carbon dioxide adsorbable liquid CL supplied to the second liquid phase region L2 can be discharged from the second liquid phase region L2. Also, since the second housing 52 has a second gas discharge port 57, carbon dioxide can be discharged and recovered from the second gas phase region G2. As a result, it is possible to continue supplying the carbon dioxide adsorbable liquid CL to the second liquid phase region L2 and continue to recover carbon dioxide from the second gas phase region G2, so that carbon dioxide can be desorbed and recovered from the carbon dioxide adsorbable liquid CL for a long period of time.

[0093] In addition, in this carbon dioxide separation and capture system 1, since each of the plurality of first hollow fiber membranes 41 and each of the plurality of second hollow fiber membranes 51 contains an olefin resin, it is possible to impart high hydrophobicity to each of the plurality of first hollow fiber membranes 41 and each of the plurality of second hollow fiber membranes 51. As a result, in each of the plurality of first hollow fiber membranes 41 and each of the plurality of second hollow fiber membranes 51, the carbon dioxide adsorbable liquid CL is less likely to penetrate into the porous layer 412 and the porous layer 512, and the porous layer 412 and the porous layer 512 are less likely to become wet. Incidentally, the dense layer 411 and the dense layer 511 have no porosity, and therefore have a structure that is less likely to be penetrated and wetted by the carbon dioxide adsorbable liquid CL, but the above structure of the dense layer 411 and the dense layer 511 may collapse due to deterioration over time. However, even if the above-mentioned structure of the dense layers 411 and 511 collapses due to deterioration over time, the high hydrophobicity of each of the multiple first hollow fiber membranes 41 and each of the multiple second hollow fiber membranes 51 makes it difficult for the carbon dioxide adsorbing liquid CL to penetrate into the dense layers 411 and 511, making it difficult for the dense layers 411 and 511 to become wet.

[0094] In addition, in this carbon dioxide separation and capture system 1, the carbon dioxide adsorbable liquid CL discharged from the desorption module 5 can be supplied to the adsorption module 4 through the liquid circulation path 9, thereby reducing the amount of carbon dioxide adsorbable liquid CL used.

[0095] In the carbon dioxide separation and capture method of this embodiment, in the carbon dioxide separation and capture system 1, a carbon dioxide adsorbable liquid CL is supplied from a liquid supply device 2 to a first liquid phase region L1, a target gas is supplied from a target gas supply device 3 to a first gas phase region G1, and carbon dioxide is captured from the second gas phase region G2 by reducing the pressure in the second gas phase region G2, thereby suppressing an early decrease in gas exchange capacity.

[0096] Although a preferred embodiment of one aspect of the present invention has been described above, one aspect of the present invention is not limited to the above embodiment.

[0097] For example, each of the first hollow fiber membranes and each of the second hollow fiber membranes may be the same as or different from each other. Similarly, the dense layer and the porous layer of each of the first hollow fiber membranes and the dense layer and the porous layer of each of the second hollow fiber membranes may be the same as or different from each other. [Industrial Applicability]

[0098] One aspect of the present invention can be used as a carbon dioxide separation and capture system and a carbon dioxide separation and capture method. [Explanation of symbols]

[0099] Reference Signs List 1... Carbon dioxide separation and capture system, 2... Liquid supply device, 21... Pump, 3... Target gas supply device, 31... Compressor, 4... Adsorption module, 41... First hollow fiber membrane, 411... Dense layer, 412... Porous layer, 42... First housing, 43... Outer region, 44... Inner region, 45... First liquid supply port, 46... First liquid outlet, 47... First gas supply port, 48... First gas outlet, 5... Desorption module, 51... Second hollow fiber membrane, 511... Dense layer, 512... Porous layer, 52 ...Second housing, 53...outer region, 54...inner region, 55...second liquid supply port, 56...second liquid exhaust port, 57...second gas exhaust port, 6...liquid communication passage, 7...gas recovery passage, 8...suction device, 81...vacuum pump, 9...liquid circulation passage, 11...liquid supply passage, 12...gas supply passage, 13...gas exhaust passage, 14...flow rate control valve, G1...first gas phase region, G2...second gas phase region, L1...first liquid phase region, L2...second liquid phase region, CL...carbon dioxide adsorbable liquid, TG...target gas.

Claims

1. an adsorption module in which a first liquid phase region and a first gas phase region are separated by a plurality of first hollow fiber membranes in order to adsorb carbon dioxide contained in a target gas into a carbon dioxide adsorbable liquid capable of adsorbing carbon dioxide; a desorption module in which a second liquid phase region and a second gas phase region are separated by a plurality of second hollow fiber membranes for desorbing carbon dioxide from the carbon dioxide adsorbable liquid; a liquid supply device connected to the first liquid phase region for supplying the carbon dioxide adsorbable liquid to the first liquid phase region; a target gas supply device connected to the first gas phase region for supplying the target gas to the first gas phase region; a liquid communication passage connected to the adsorption module and the desorption module, communicating the first liquid phase region with the second liquid phase region; a gas recovery passage communicating with the second gas phase region; Each of the first hollow fiber membranes and each of the second hollow fiber membranes have a dense layer having no porosity and a porous layer located inside the dense layer and having porosity; The porosity of the porous layer is 5% or more and 60% or less, Each of the first hollow fiber membranes and each of the second hollow fiber membranes contains an olefin resin (excluding those in which each of the first hollow fiber membranes and each of the second hollow fiber membranes contains polytetrafluoroethylene), Carbon dioxide capture system.

2. The carbon dioxide adsorbing liquid is an ionic liquid. The carbon dioxide separation and capture system according to claim 1 .

3. The carbon dioxide adsorbable liquid is a deep eutectic solvent; The carbon dioxide separation and capture system according to claim 1 .

4. The dense layer does not have pores through which the carbon dioxide adsorbable liquid can pass. The carbon dioxide separation and capture system according to claim 1 .

5. The dense layer does not have pores with a pore size of 0.01 μm or more. The carbon dioxide separation and capture system according to claim 1 .

6. The dense layer is formed on the outer surface of each of the first hollow fiber membranes and the outer surface of each of the second hollow fiber membranes. The carbon dioxide separation and capture system according to claim 1 .

7. The separation coefficient of carbon dioxide relative to nitrogen of each of the first hollow fiber membranes and each of the second hollow fiber membranes is 2 or more and 20 or less. The carbon dioxide separation and capture system according to claim 1 .

8. the first liquid phase region is a region located outside each of the first hollow fiber membranes, The second liquid phase region is a region located outside each of the plurality of second hollow fiber membranes. The carbon dioxide separation and capture system according to claim 1 .

9. The gas recovery passage further includes a suction device for reducing the pressure in the second gas phase region. The carbon dioxide separation and capture system according to claim 1 .

10. The target gas supply device has a compressor for compressing the target gas and supplying it to the first gas phase region. The carbon dioxide separation and capture system according to claim 1 .

11. the adsorption module has a first housing that accommodates the first hollow fiber membranes to form the first liquid phase region and the first gas phase region; The first housing includes: a first liquid supply port that opens the first liquid phase region so as to supply the carbon dioxide adsorbable liquid supplied from the liquid supply device to the first liquid phase region; a first liquid discharge port that opens the first liquid phase region to discharge the carbon dioxide adsorbable liquid supplied to the first liquid phase region from the first liquid phase region to the liquid communication passage; a first gas supply port that opens the first gas phase region so as to supply the target gas supplied from the target gas supply device to the first gas phase region; a first gas exhaust port that opens the first gas phase region to exhaust the target gas supplied to the first gas phase region from the first gas phase region, The carbon dioxide separation and capture system according to claim 1 .

12. the desorption module has a second housing that accommodates the second hollow fiber membranes to form the second liquid phase region and the second gas phase region, The second housing includes: a second liquid supply port that opens the second liquid phase region to supply the carbon dioxide adsorbable liquid from the liquid communication passage to the second liquid phase region; a second liquid outlet that opens the second liquid phase region to discharge the carbon dioxide adsorbable liquid supplied to the second liquid phase region from the second liquid phase region; and a second gas outlet opening the second gas phase region to discharge carbon dioxide from the second gas phase region. The carbon dioxide separation and capture system according to claim 1 .

13. A carbon dioxide separation and capture method using the carbon dioxide separation and capture system according to any one of claims 1 to 12, supplying the carbon dioxide adsorbable liquid from the liquid supply device to a first liquid phase region; supplying the target gas from the target gas supply device to the first gas phase region; Recovering carbon dioxide from the second gas phase region by reducing the pressure in the second gas phase region. Carbon dioxide separation and capture method.

Images