Air reclamation system and method, and spacecraft

Abstract

To provide an air regeneration technique for a manned closed space improved from the viewpoint of operation energy reduction.SOLUTION: An air regeneration system for removing carbon dioxide from air in a manned closed space includes a carbon dioxide adsorption device that has an adsorption container containing an adsorbent that adsorbs carbon dioxide and that removes carbon dioxide from air by bringing air into contact with the adsorbent, a feed flow path that feeds air from the manned closed space to the carbon dioxide adsorption device, a return flow path that feeds air from which carbon dioxide has been removed from the carbon dioxide adsorption device to the manned closed space, a feed flow path that constitutes a part of the feed flow path, a sweep flow path that constitutes a part of the return flow path, and a steam permeable membrane that separates the feed flow path and the sweep flow path. And a dehumidification membrane module for humidifying the dried air in the return flow path.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to air reclamation technology for removing carbon dioxide from the air in occupied enclosed spaces. [Background technology]

[0002] Manned spacecraft such as spaceships and space stations are equipped with environmental control and life support systems that maintain the environment of manned enclosed spaces closed off from the outside in a state where life can continue. This system is made up of a combination of subsystems with various functions, such as adjusting the temperature and humidity of manned enclosed spaces and regenerating the air to remove carbon dioxide.

[0003] An example of an air regeneration system that realizes an air regeneration function is disclosed in Patent Document 1. The system in Patent Document 1 includes a pressurization means for pressurizing moist air in a pressurized, sealed living space such as a space station; a dehumidification tower that brings the pressurized moist air into contact with a desiccant to produce dry air; and an adsorption tower that brings the dry air into contact with an adsorbent to adsorb and remove carbon dioxide. When the desiccant in the dehumidification tower that has adsorbed moisture is regenerated by heating, the desiccant is brought into contact with dry air from which carbon dioxide has been removed, thereby promoting the drying of the desiccant and humidifying the dry air to produce moist air. The moist air is sent to the sealed living space and recycled. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-141040 Summary of the Invention [Problem to be solved by the invention]

[0005] In a system equipped with a dehumidifying tower that uses a moisture-absorbing desiccant, as in Patent Document 1, a regeneration process is required to regenerate the moisture-containing desiccant by drying it. This regeneration process requires thermal energy to heat the desiccant, and there is still room for improvement from the perspective of reducing the operating energy of the system. [Means for solving the problem]

[0006] In order to solve the above problems, an air regeneration system according to one aspect of the present disclosure includes: 1. An air reclamation system for removing carbon dioxide from air in an occupied enclosed space, comprising: a carbon dioxide adsorber having an adsorption vessel containing an adsorbent that adsorbs carbon dioxide, and removing carbon dioxide from the air by bringing the air into contact with the adsorbent; a feed flow path for feeding air from the manned enclosed space to the carbon dioxide adsorber; a return flow path that sends the air from which carbon dioxide has been removed from the carbon dioxide adsorber to the manned enclosed space; The system includes a feed flow path that constitutes a part of the feed flow path, a sweep flow path that constitutes a part of the return flow path, and a dehumidifying membrane module that has a water vapor permeable membrane that separates the feed flow path and the sweep flow path, and that dehumidifies the humid air in the feed flow path and humidifies the dry air in the return flow path.

[0007] Furthermore, a spacecraft according to one aspect of the present disclosure includes a manned cabin having a manned enclosed space therein, and the above-described air regeneration system that removes carbon dioxide from the air in the manned enclosed space.

[0008] Further, an air regeneration method according to one aspect of the present disclosure is a method for regenerating air in a manned closed space isolated from the atmosphere, dehumidifying the air sucked from the manned confined space by passing the air through a dehumidifying membrane module having a feed flow path, a sweep flow path, and a water vapor permeable membrane separating the feed flow path and the sweep flow path; contacting the dehumidified air with an adsorbent that adsorbs carbon dioxide to remove carbon dioxide; humidifying the air from which carbon dioxide has been removed by passing it through the sweep flow path of the dehumidifying membrane module; and and returning the humidified air to the occupied enclosed space. [Effects of the Invention]

[0009] According to the present disclosure, an air regeneration technology for manned enclosed spaces can be provided that is improved from the perspective of reducing operating energy. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of an air regeneration system according to one embodiment of the present disclosure. [Figure 2] Figure 2 is a functional image diagram of the dehumidifying membrane module. DETAILED DESCRIPTION OF THE INVENTION

[0011] Next, an embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic diagram of an air reclamation system 1 according to one aspect of the present disclosure. In the figure, open valves indicate an open state, and solid valves indicate a closed state. As shown in FIG. 1, the air reclamation system 1 according to this embodiment is mounted on a manned spacecraft 10, such as a spaceship or a space station. The spacecraft 10 has a manned compartment 12, such as a cabin, and regenerates the air by removing carbon dioxide from the air in a manned enclosed space 11 formed inside the manned compartment 12. The manned enclosed space 11 is a sealable space closed from the outside and used by humans. However, the air reclamation system 1 according to the present disclosure can be applied not only to the spacecraft 10 but also to removing carbon dioxide from the air in a manned enclosed space 11 isolated from the atmosphere, such as an underwater vehicle or an underground facility.

[0012] The air regeneration system 1 includes a circulation path 20 that returns moist air taken out from the manned confined space 11 to the manned confined space 11 after removing carbon dioxide therefrom in a carbon dioxide adsorber 23. The circulation path 20 includes a feed flow path 20a that sends the air from the manned confined space 11 to the carbon dioxide adsorber 23, and a return flow path 20b that sends the air from which carbon dioxide has been removed from the carbon dioxide adsorber 23 to the manned confined space 11.

[0013] <Air flow in the feed flow path 20a> In the feed flow path 20a of the circulation path 20, a blower 21 and a feed flow path 221 of the dehumidifying membrane module 22 are provided.

[0014] The blower 21 draws moist air from the manned confined space 11 into the circulation path 20 and sends it downstream. The blower 21 pressurizes the moist air to a pressure suitable for use as a feed flow for the dehumidifying membrane module 22. In a non-limiting numerical example, the pressure in the manned confined space 11 is approximately 0.1 MPa, and the pressure of the moist air after being pressurized by the blower 21 is approximately 0.1-1.0 MPa higher than the pressure in the manned confined space 11. However, the blower 21 need only be capable of extracting air from the manned confined space 11 and sending it to the carbon dioxide adsorber 23; the air does not have to be pressurized. The blower 21 may be a fan, blower, compressor, or the like, suitable for the degree of air pressurization.

[0015] FIG. 2 is a functional conceptual diagram of the dehumidifying membrane module 22. As shown in FIG. 2, the dehumidifying membrane module 22 includes a feed flow path 221, a sweep flow path 222, and a water vapor permeable membrane 223 separating the feed flow path 221 and the sweep flow path 222. Dry air pressurized by the blower 21 is supplied to the feed flow path 221 as a feed flow, and dry air from which carbon dioxide has been removed by the carbon dioxide adsorber 23 is supplied to the sweep flow path 222 as a sweep flow. The pressure of the feed flow path 221 is higher than the pressure of the sweep flow path 222. However, as long as the water vapor partial pressure of the feed flow path 221 is higher than the water vapor partial pressure of the sweep flow path 222, the pressure of the feed flow path 221 and the pressure of the dehumidifying membrane module 22 may be the same. The feed flow and the sweep flow are directed in opposite directions, and the dehumidifying membrane module 22 is configured as a sweep-type counterflow module.

[0016] The water vapor permeable membrane 223 is a membrane that selectively allows water vapor in a gas to permeate or that preferentially allows water vapor in a gas to permeate over other gases, and is also referred to as a water vapor separation membrane. The water vapor permeable membrane 223 may be a membrane that is permeable to gases other than water vapor, as long as the membrane has a water vapor permeation rate sufficiently faster than that of carbon dioxide and allows water vapor to permeate preferentially over carbon dioxide. Polyimide hollow fiber membranes or fluorine-based ion exchange resin hollow fiber membranes can be used as such water vapor permeable membranes. The dehumidifying membrane module 22 using hollow fiber membranes includes, for example, a large number of straw-shaped hollow fiber membranes arranged in a cylindrical casing, and is configured so that a feed flow flows inside the hollow fiber membranes and a sweep flow flows outside the hollow fiber membranes.

[0017] The water vapor permeable membrane 223 has the property of reducing the difference in water vapor partial pressure between the moist air in the feed flow path 221 and the dry air in the sweep flow path 222, i.e., the difference in humidity between the feed flow path 221 and the sweep flow path 222. Therefore, the water vapor in the moist air in the feed flow path 221 permeates the water vapor permeable membrane 223 and moves to the sweep flow path 222, which has a lower humidity.

[0018] The moist air pressurized by the blower 21 is supplied to the feed flow path 221 of the dehumidifying membrane module 22. Water vapor contained in the moist air that has flowed into the feed flow path 221 as a feed flow becomes a permeate flow that permeates the water vapor permeable membrane 223 and moves to the sweep flow path 222. The retentate flow that did not permeate the water vapor permeable membrane 223 has its humidity reduced by the removal of water vapor, and is discharged from the feed flow path 221 as dry air.

[0019] Carbon dioxide adsorber 23 Returning to Fig. 1, the carbon dioxide adsorber 23 removes carbon dioxide by adsorption from the moist air dehumidified by the dehumidifying membrane module 22, i.e., from the dry air. The carbon dioxide adsorber 23 has a plurality of adsorption vessels connected in parallel to a circulation path 20 between a first adsorption vessel 231 and a second adsorption vessel 232. The first adsorption vessel 231 and the second adsorption vessel 232 are filled with an adsorbent 33 that adsorbs carbon dioxide. As the adsorbent 33, for example, zeolite or an amine-based solid adsorbent in which an amine-based carbon dioxide absorbent is supported on a porous carrier such as zeolite may be used.

[0020] The circulation path 20 is provided with flow path switching valves 24a, 24b that switch between the first adsorption vessel 231 and the second adsorption vessel 232 of the carbon dioxide adsorber 23 and the adsorption vessel through which the dry air flows. In principle, while one of the first adsorption vessel 231 and the second adsorption vessel 232 is adsorbing carbon dioxide, the other is regenerating the adsorbent 33. By alternately switching the adsorption vessel that adsorbs carbon dioxide, the carbon dioxide adsorber 23 can continuously remove carbon dioxide.

[0021] The adsorption vessel in which the adsorbent 33 is regenerated is connected to the outside of the spacecraft 10 via a vent passage 27 and is heated by a heater 31. Either the first adsorption vessel 231 or the second adsorption vessel 232 is connected to the vent passage 27 by a vent switching valve 28. The vent switching valve 28 can be switched among a state in which only the first adsorption vessel 231 is connected to the outside of the spacecraft, a state in which only the second adsorption vessel 232 is connected to the outside of the spacecraft, and a state in which both the first adsorption vessel 231 and the second adsorption vessel 232 are isolated from the outside of the spacecraft. In this embodiment, the vessel in which the adsorbent 33 is regenerated is connected to outer space, which is the outside of the spacecraft 10, by the vent passage 27. The pressure inside the vessel is reduced by the vacuum of outer space, and the adsorbent 33 filled in the vessel is heated by the heater 31, causing the carbon dioxide adsorbed in the adsorbent 33 to desorb from the adsorbent 33. The carbon dioxide desorbed from the adsorbent 33 passes through the vent passage 27 and is discharged outside the aircraft.

[0022] Dry air from the dehumidifying membrane module 22 is introduced into the adsorption vessel where carbon dioxide adsorption takes place. The dry air flowing through the adsorption vessel comes into contact with the adsorbent 33, and the carbon dioxide in the dry air is adsorbed by the adsorbent 33. This removes the carbon dioxide contained in the dry air, and the carbon dioxide concentration in the dry air, i.e., the carbon dioxide partial pressure, decreases.

[0023] <Air flow in the return flow path 20b> The return flow path 20b of the circulation path 20 is provided with a sweep flow path 222 of the dehumidifying membrane module 22.

[0024] The dry air from which carbon dioxide has been removed in the carbon dioxide adsorber 23 is supplied to the sweep flow path 222 of the dehumidifying membrane module 22. Almost all of the dry air discharged from the carbon dioxide adsorber 23 flows through the sweep flow path 222. A sweep flow is formed by the dry air that has flowed into the sweep flow path 222.

[0025] The dry air flowing through the sweep flow path 222 is humidified by mixing with water vapor that has permeated the water vapor permeable membrane 223 from the feed flow path 221 and moved to the sweep flow path 222, and the resulting moist air is discharged from the sweep flow path 222. The moist air discharged from the sweep flow path 222 is sent to the manned enclosed space 11 through the return flow path 20b.

[0026] Because the feed flow path 221 and the sweep flow path 222 of the dehumidifying membrane module 22 are provided on a single circulation path 20, the flow rate of the wet air supplied to the feed flow path 221 and the flow rate of the dry air supplied to the sweep flow path 222 are substantially equal. However, because the dry air supplied to the sweep flow path 222 has water vapor and carbon dioxide removed from the wet air supplied to the feed flow path 221, strictly speaking, the flow rate of the dry air is slightly lower than the flow rate of the wet air. In this way, in the dehumidifying membrane module 22, by using the dry air in the return flow path 20b as a feed gas, a sweep flow with a flow rate substantially equal to that of the feed flow can be formed. By forming a sweep flow with a sufficient flow rate in the sweep flow path 222, it is possible to maintain a large transmembrane pressure difference, i.e., a large difference between the water vapor partial pressure in the feed flow path 221 and the water vapor partial pressure in the sweep flow path 222, compared to a counterflow module without a sweep gas supply. This promotes the permeation of water vapor through the water vapor permeable membrane 223, improving the separation performance of the dehumidifying membrane module 22.

[0027] [Summary] The air regeneration system 1 according to the first item of the present disclosure is an air regeneration system 1 that removes carbon dioxide from the air in a manned enclosed space 11, a carbon dioxide adsorber (23) having adsorption vessels (231, 232) containing an adsorbent (33) that adsorbs carbon dioxide, and removing carbon dioxide from the air by bringing the air into contact with the adsorbent (33); a feed flow path 20a for sending air from the manned enclosed space 11 to the carbon dioxide adsorber 23; a return flow path 20b that sends the air from which carbon dioxide has been removed from the carbon dioxide adsorber 23 to the manned enclosed space 11; The dehumidifying membrane module 22 includes a feed flow path 221 that forms part of the feed flow path 20a, a sweep flow path 222 that forms part of the return flow path 20b, and a water vapor permeable membrane 223 that separates the feed flow path 221 and the sweep flow path 222, and dehumidifies the moist air in the feed flow path 20a and humidifies the dry air in the return flow path 20b.

[0028] In the air regeneration system 1 configured as described above, a dehumidifying membrane module 22 is used to dehumidify the air sent from the manned enclosed space 11 to the carbon dioxide adsorber 23. In conventional desiccant adsorption dehumidifiers, the desiccant, such as silica gel, must be heated to regenerate it, which requires thermal energy. In contrast, the dehumidifying membrane module 22 does not require regeneration processing, which reduces the energy required for the regeneration processing. This ultimately reduces the energy required to operate the air regeneration system 1.

[0029] The adsorbent 33 of the carbon dioxide adsorber 23 can adsorb a small amount of water vapor in addition to carbon dioxide, but in the air regeneration system 1 configured as described above, the amount of water vapor adsorbed by the adsorbent 33 can be reduced because the water vapor is reduced in the air supplied to the carbon dioxide adsorber 23. This makes it possible to reduce the heating energy of the heater 31 for regenerating the adsorbent 33. Consequently, the energy required for operating the air regeneration system 1 can be reduced.

[0030] Normally, the water vapor adsorbed by the adsorbent 33 is released from the adsorbent 33 and released outside the system when the adsorbent 33 is regenerated, just like the carbon dioxide adsorbed by the adsorbent 33. In contrast, in the air regeneration system 1 configured as described above, the amount of water vapor adsorbed by the adsorbent 33 can be suppressed, and therefore the amount of water vapor released outside the system when the adsorbent 33 is regenerated can be suppressed, thereby reducing moisture loss within the system.

[0031] In the air regeneration system 1 configured as described above, dry air returning from the carbon dioxide adsorber 23 to the manned enclosed space 11 flows through the sweep flow path 222 of the dehumidifying membrane module 22. A sweep flow is formed by the dry air flowing through the sweep flow path 222. Compared to a counterflow module that does not receive a sweep gas supply, the dehumidifying membrane module 22 can maintain a state in which the difference between the water vapor partial pressure in the feed flow path 221 and the water vapor partial pressure in the sweep flow path 222 is large. This promotes permeation of water vapor through the water vapor permeable membrane 223, improving the separation performance of the dehumidifying membrane module 22.

[0032] The air regeneration system 1 according to the second item of the present disclosure is the air regeneration system 1 according to the first item, in which the entire amount of dry air coming out of the carbon dioxide adsorber 23 flows through the sweep flow path 222.

[0033] In the air regeneration system 1 configured as described above, a sweep flow with a sufficient flow rate is formed in the sweep flow path 222, and it is possible to maintain a large difference in the water vapor partial pressure between the feed flow path 221 and the sweep flow path 222. This promotes the permeation of water vapor through the water vapor permeable membrane 223, improving the separation performance of the dehumidifying membrane module 22.

[0034] A spacecraft 10 according to the third item of the present disclosure comprises a manned cabin 12 having a manned enclosed space 11 therein, and an air regeneration system 1 according to the first or second item that removes carbon dioxide from the air in the manned enclosed space 11.

[0035] The above-described air regeneration system 1 is suitable for use in a spacecraft 10 because it can suppress the amount of moisture released outside the system, can recycle and reuse moisture within the system, and can reduce operating energy.

[0036] The spacecraft 10 according to the fourth item of the present disclosure is the spacecraft 10 according to the third item, The adsorption vessels of the carbon dioxide adsorption device 23 include a first adsorption vessel 231 and a second adsorption vessel 232, The air regeneration system 1 includes a flow path switching valve 24 that switches the adsorption vessels connected to the feed flow path 20a and the return flow path 20b between the first adsorption vessel 231 and the second adsorption vessel 232, a heater 31 that heats the adsorption vessels of the first adsorption vessel 231 and the second adsorption vessel 232 that are not connected to the feed flow path 20a and the return flow path 20b, and a vent flow path 27 that connects them to the outside of the spacecraft 10.

[0037] The spacecraft 10 according to the fifth aspect of the present disclosure is the spacecraft 10 according to the third aspect, The adsorption vessels of the carbon dioxide adsorption device 23 include a first adsorption vessel 231 and a second adsorption vessel 232, The air regeneration system 1 has a flow path switching valve 24 that switches the adsorption vessels connected to the feed flow path 20a and the return flow path 20b between the first adsorption vessel 231 and the second adsorption vessel 232, and a vent flow path 27 that connects the adsorption vessels of the first adsorption vessel 231 and the second adsorption vessel 232 that are not connected to the feed flow path 20a and the return flow path 20b with the outside of the spacecraft 10.

[0038] In the spacecraft 10 according to the fourth and fifth aspects, the vacuum of outer space can be utilized to reduce the pressure in the adsorption vessels 231, 232 that house the adsorbent 33 to be regenerated. Therefore, no energy is required to reduce the pressure in the adsorption vessels 231, 232, and the operating energy of the air regeneration system 1 can be reduced.

[0039] The air regeneration method according to the sixth aspect of the present disclosure is a method for regenerating air in a manned closed space 11 isolated from the atmosphere, dehumidifying the air sucked from the manned enclosed space 11 through the feed flow path 221 of the dehumidifying membrane module 22 having a feed flow path 221, a sweep flow path 222, and a water vapor permeable membrane 223 separating the feed flow path 221 and the sweep flow path 222; contacting the dehumidified air with an adsorbent 33 that adsorbs carbon dioxide to remove carbon dioxide; Humidifying the air from which carbon dioxide has been removed by passing it through the sweep flow path 222 of the dehumidifying membrane module 22; and and returning the humidified air to the manned enclosed space 11.

[0040] According to the air regeneration method, a dehumidifying membrane module 22 is used to dehumidify the air sent from the manned enclosed space 11 to the carbon dioxide adsorber 23. In conventional desiccant adsorption dehumidifiers, the desiccant, such as silica gel, must be heated to regenerate it, which requires thermal energy. In contrast, the dehumidifying membrane module 22 does not require regeneration processing, which reduces the energy required for the regeneration processing. This in turn reduces the energy required for operating the air regeneration system 1.

[0041] The above-described embodiments have been presented for purposes of illustration and description and are not intended to limit the present disclosure to the form disclosed herein. For example, in the foregoing detailed description, various features of the present disclosure are grouped together in a single embodiment for the purpose of streamlining the disclosure, but some of the features may also be combined. Furthermore, the features included in the present disclosure may also be combined into alternative embodiments, configurations, or aspects other than those discussed above. [Explanation of symbols]

[0042] 1: Air regeneration system 10: Spacecraft 11: Manned closed space 12: Manned room 20: Circulation route 20a: Feed channel 20b: Return channel 21: Blower 22: Dehumidifying membrane module 23: Carbon dioxide adsorber 24a, 24b: flow path switching valve 27: Vent channel 31: Heater 33: Adsorbent 221: Feed channel 222: Sweep channel 223: Water vapor permeable membrane 231,232 :Adsorption container

Claims

1. 1. An air reclamation system for removing carbon dioxide from air in an occupied enclosed space, comprising: a carbon dioxide adsorber having an adsorption vessel containing an adsorbent that adsorbs carbon dioxide, and removing carbon dioxide from the air by bringing the air into contact with the adsorbent; a feed flow path for feeding air from the manned enclosed space to the carbon dioxide adsorber; a return flow path that sends the air from which carbon dioxide has been removed from the carbon dioxide adsorber to the manned enclosed space; a feed flow path constituting a part of the feed flow path, a sweep flow path constituting a part of the return flow path, and a dehumidifying membrane module having a water vapor permeable membrane separating the feed flow path and the sweep flow path, and dehumidifying humid air in the feed flow path and humidifying dry air in the return flow path; Air regeneration system.

2. The entire amount of dry air discharged from the carbon dioxide adsorber flows through the sweep flow path.

10. The air reclamation system of claim 1.

3. a manned room having a manned closed space therein; and an air regeneration system according to claim 1 or 2, which removes carbon dioxide from the air in the manned enclosed space. Spacecraft.

4. the adsorption vessels of the carbon dioxide adsorber include a first adsorption vessel and a second adsorption vessel; the air regeneration system includes a flow path switching valve that switches the adsorption vessels connected to the feed flow path and the return flow path between the first adsorption vessel and the second adsorption vessel, a heater that heats the adsorption vessel that is not connected to the feed flow path and the return flow path among the first adsorption vessel and the second adsorption vessel, and a vent flow path that communicates with the outside of the spacecraft.

4. The spacecraft according to claim 3.

5. the adsorption vessels of the carbon dioxide adsorber include a first adsorption vessel and a second adsorption vessel; the air regeneration system includes a flow path switching valve that switches between the adsorption vessels connected to the feed flow path and the return flow path between the first adsorption vessel and the second adsorption vessel, and a vent flow path that connects the adsorption vessel, of the first adsorption vessel and the second adsorption vessel, that is not connected to the feed flow path and the return flow path, to the outside of the spacecraft.

4. The spacecraft according to claim 3.

6. A method for regenerating air in a manned enclosed space isolated from the atmosphere, comprising: dehumidifying the air sucked from the manned confined space by passing the air through a dehumidifying membrane module having a feed flow path, a sweep flow path, and a water vapor permeable membrane separating the feed flow path and the sweep flow path; contacting the dehumidified air with an adsorbent that adsorbs carbon dioxide to remove carbon dioxide; humidifying the air from which carbon dioxide has been removed by passing it through the sweep flow path of the dehumidifying membrane module; and returning the humidified air to the occupied enclosed space. Air regeneration method.

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