Gas transport equipment, water desalination equipment, carbon dioxide adsorption equipment, and carbon dioxide recovery system

Abstract

This provides a new technology that enables the recovery of high concentrations of CO2 from low concentrations of target gases. [Solution] The CO2 recovery system (1) includes a dehumidifying tower (10) and a CO2 absorption tower (20). Both the dehumidifying tower (10) and the CO2 absorption tower (20) include a configuration that cools the pipe structure (tower body 11 or vent pipe 24), which has an open upper end, from bottom to top, and this cooling causes the (dry) air to move from top to bottom within the pipe structure.

Description

Technical Field

[0001] The present invention relates to a gas transport device, a water production device, a carbon dioxide adsorption device, and a carbon dioxide recovery system.

Background Art

[0002] Carbon dioxide contained in exhaust gas generated after combustion of fuel or in the atmosphere or the like is regarded as a cause of global warming. In order to prevent global warming, a technology for separating and recovering carbon dioxide from exhaust gas or the atmosphere or the like is required. Such a technology includes cooling a target gas containing carbon dioxide and pressurized to a specific temperature using the cold heat of liquefied natural gas or liquid hydrogen, adsorbing the carbon dioxide in the target gas to an adsorbent, and then desorbing it from the adsorbent at a higher temperature, and separating and recovering the carbon dioxide in the target gas by alternately performing such adsorption and desorption (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when the target gas is the atmosphere, the concentration of carbon dioxide in the target gas is as low as about 400 ppm. In the conventional technology as described above, there remains room for consideration from the viewpoint of releasing high-concentration carbon dioxide from such a low-concentration target gas, and a technology capable of recovering high-concentration carbon dioxide from a low-concentration target gas is required.

[0005] One aspect of the present invention aims to provide a new technology capable of recovering high-concentration carbon dioxide from a low-concentration target gas.

Means for Solving the Problems

[0006] As a means to solve the above problems, the present invention provides embodiments relating to the following [1] to

[20] .

[0007] [1] A gas transport device that moves the gas to be transported from the supply source from top to bottom within the pipe, the device comprising: a pipe whose upper end is open to a supply source of the gas to be transported when installed vertically; and a cooling unit that lowers the temperature inside the pipe as it goes down. [2] The gas conveying apparatus according to [1] above, wherein the temperature in the lower part of the pipe is 30°C or more lower than the temperature in the upper part of the pipe. [3] The gas transport device according to [1] or [2] above, wherein the degree of voids in the pipe is 70% or less and 25% or more. [4] A gas transport device according to any one of [1] to [3] above, wherein the temperature at the bottom of the pipe is between -70°C and -253°C. [5] A gas conveying device according to any one of [1] to [4] above, wherein the temperature gradient between the upper and lower parts of the pipe is 50°C / m or more and 200°C / m or less. [6] The gas transport device according to any one of [1] to [5] above, wherein the cooling unit is a heat exchanger located inside the pipe and supplied with a refrigerant from bottom to top. [7] The gas transport device according to any one of [1] to [5] above, wherein the cooling section has an outer shell structure that covers the outer surface of the pipe and on the outside of the pipe a refrigerant is supplied from bottom to top. [8] The gas transport apparatus according to any one of [1] to [5] above, wherein the cooling section is a permeable layer housed in the pipe, the lower part of which is at a lower temperature than the upper part. [9] The gas transport apparatus according to any one of [1] to [8] above, further comprising a permeable adsorption layer for adsorbing carbon dioxide inside the pipe.

[10] The gas transport apparatus according to [9] above, wherein the adsorption layer is a packed layer formed by filling the tube with a porous material having pores of 10 Å or less.

[11] The gas transport apparatus according to [6] or [7] above, wherein the refrigerant is a liquefied gas.

[12] The gas transport apparatus according to

[11] above, wherein the liquefied gas is liquefied natural gas.

[13] The gas transport apparatus according to

[11] above, wherein the liquefied gas is liquid hydrogen.

[14] A gas conveying device according to any one of [1] to

[13] above, wherein the gas to be treated is air.

[0008]

[15] A water production apparatus comprising a pipe extending vertically, the upper end of which is open to the atmosphere, and a heat exchanger disposed inside the pipe, to which liquefied gas is supplied from below to above as a refrigerant, wherein water in the air adhering to the heat exchanger is recovered.

[0009]

[16] A carbon dioxide adsorption device comprising: a pipe extending vertically, the upper end of which is open to a source of dehumidified air; a permeable adsorption layer housed within the pipe that adsorbs carbon dioxide; and an outer shell structure that covers the outer surface of the pipe and from which liquefied gas is supplied from below as a refrigerant outside the pipe, wherein dehumidified air is supplied to the pipe from above and carbon dioxide in the air is adsorbed onto the adsorption layer.

[17] The carbon dioxide adsorption apparatus according to

[16] , further comprising a flow path switching device for switching the airflow path to the pipe such that the upper end of the pipe is open to a supply source of air that is dehumidified, has carbon dioxide removed, and has a temperature above the temperature at which the adsorption layer desorbs carbon dioxide.

[0010]

[18] A carbon dioxide recovery system for recovering carbon dioxide from air, comprising a water production apparatus as described in

[15] above, and a carbon dioxide adsorption apparatus as described in

[17] above, wherein dehumidified air produced by the water production apparatus is supplied to a pipe from above.

[19] The carbon dioxide recovery system according to

[18] , wherein one or both of the heat exchanger and the outer shell structure also serve as a vaporizer for vaporizing the liquid liquefied gas in a liquefied gas treatment device for vaporizing the liquid liquefied gas. [Effects of the Invention]

[0011] According to one aspect of the present invention, it is possible to provide a new technology capable of recovering high-concentration carbon dioxide from a low-concentration target gas.

[0012] In another aspect of the present invention, it is also possible to provide a technology that can be used as a gas transport device or a water production device that requires less energy for transportation.

Brief Description of the Drawings

[0013] [Figure 1] It is a diagram schematically showing the configuration of a carbon dioxide recovery system according to an embodiment of the present invention. [Figure 2] It is a diagram schematically showing the configuration of a dehumidification tower in an embodiment of the present invention. [Figure 3] It is a diagram schematically showing the configuration of a carbon dioxide absorption tower in an embodiment of the present invention. [Figure 4] It is a diagram schematically showing the configuration of a heat exchanger in an embodiment of the present invention.

Modes for Carrying Out the Invention

[0014] Hereinafter, an embodiment of the present invention will be described. In this specification, "~" means a range including both ends thereof unless otherwise specified.

[0015] [Configuration] In addition to the configuration required for a gas transport device, by explaining the operation when operating as a carbon dioxide recovery device, the present invention can be more easily understood, and the configuration as a water production device can also be easily understood. Therefore, first, the present invention will be described with the configuration of a carbon dioxide recovery system. The configuration of a carbon dioxide recovery system according to an embodiment of the present invention is schematically shown in FIG. 1. As shown in FIG. 1, the carbon dioxide recovery system 1 has a dehumidification tower 10 and a carbon dioxide absorption tower 20.

[0016] [Dehumidification Tower] The dehumidification tower 10 has a heat medium pipe through which a heat medium flows inside, and connection nozzles H1 and H2 of the heat medium pipe are provided at the lower and upper parts of the dehumidification tower 10, respectively. Further, the dehumidification tower 10 is arranged at its upper part such that a gas containing carbon dioxide, for example, outside air, can be supplied, and a first pipe 51 is connected to its lower part.

[0017] The configuration of the dehumidification tower 10 is schematically shown in FIG. 2. The dehumidification tower 10 has a tower body 11, a heat medium pipe 12, fins 13, and an opening 14. The tower body 11 is a bottomed cylindrical member, and has an opening 14 at its upper part and is open upward. A first pipe 51 is connected to the bottom of the tower body 11, and thus the tower body 11 is configured such that the contents of the tower body 11 are discharged from the bottom.

[0018] The heat medium pipe 12 is arranged inside the tower body 11 and is a pipe that extends in a meandering manner from bottom to top. The heat medium pipe 12 is connected to the connection nozzle H1 at its lower end and to the connection nozzle H2 at its upper end. Further, the heat medium pipe 12 is arranged so as to penetrate through a plurality of heat dissipation plates constituting the fins 13. Thus, the heat medium pipe 12 and the fins 13 constitute a heat exchanger arranged inside the tower body 11.

[0019] Note that a drain pipe 55 branches from the first pipe 51, and the drain pipe 55 is connected to a water storage tank 71. Opening and closing valves v1, v2, and v3 are arranged between the branch point of the first pipe 51 and the drain pipe 55 and the dehumidification tower 10, on the downstream side of the branch point in the first pipe 51, and on the upstream side of the water storage tank 71 in the drain pipe 55, respectively.

[0020] [Carbon Dioxide Absorption Tower] The carbon dioxide absorption tower 20 is connected to the first piping 51 at its upper end and to the second piping 52 at its lower end. The carbon dioxide absorption tower 20 also has connection nozzles H3 and H4 for the heat transfer medium piping at its lower and upper ends, respectively. The carbon dioxide absorption tower 20 is connected to the first piping 51 at its upper end and to the second piping 52 at its lower end. The second piping 52 is connected to the first gas tank 72.

[0021] Figure 3 schematically shows the configuration of the carbon dioxide absorption tower 20. The carbon dioxide absorption tower 20 has a configuration similar to that of a so-called core-shell type multi-tube reactor. The carbon dioxide absorption tower 20 has a shell body 21, partition plates 22 and 23, and vent pipes 24. The shell body 21 is an airtight container with piping connected to both ends, and its interior is divided by two partition plates 22 and 23 into vent sections 25 and 26 at the ends and a heat transfer medium flow section 27 in the center. Multiple vent pipes 24 are arranged along the axial direction of the shell body 21 in the central section, and through holes are formed in the parts of the partition plates 24 that the ends of the vent pipes 24 abut against. In this way, the vent pipes 24 are configured to supply gas supplied to one vent section 25 of the shell body 21 to the other vent section 26. Connecting nozzles H3 and H4 are positioned at the ends of the heat transfer fluid circulation section 27 in the central part of the shell body 21. The central part of the shell body 21 (outside the ventilation pipe 24) is filled with the heat transfer fluid, and the heat transfer fluid is circulated from one end of the central part to the other. Each of the ventilation pipes 24 is filled with a particulate packing material, which will be described later.

[0022] Thus, the carbon dioxide absorption tower 20 includes a pipe structure (vent pipe 24) whose upper end is open to the source of the gas to be treated (dry air) when installed vertically. Furthermore, the carbon dioxide absorption tower 20 includes a permeable adsorption layer inside the pipe structure that adsorbs carbon dioxide. This permeable layer is a permeable adsorption layer that adsorbs carbon dioxide.

[0023] In the descriptions of the gas transport device, water desalination device, carbon dioxide adsorption device, carbon dioxide recovery system, etc., of the present invention, the term "vertical direction" does not necessarily have to perfectly coincide with the direction of gravitational acceleration; it is merely a term used to clearly indicate the up and down direction.

[0024] Furthermore, a concentrated gas pipe 54 branches off from the second pipe 52, and the concentrated gas pipe 54 is connected to the second gas tank 73. On-off valves v4, v5, and v6 are located between the branching point of the second pipe 52 and the concentrated gas pipe 54 and the carbon dioxide absorption tower 20, downstream of the branching point in the second pipe 52, and upstream of the second gas tank 73 in the concentrated gas pipe 54, respectively.

[0025] Furthermore, a recirculating gas pipe 53 branches off from the second pipe 52 downstream of the branching point with the concentrated gas pipe 54. On-off valves v7, v8, and v9 are located upstream and downstream of the branching point between the second pipe 52 and the recirculating gas pipe 53, and upstream of the first gas tank 72 in the second pipe 52, respectively.

[0026] The recirculating gas piping 53 is connected to the first piping 51 on the upstream side of the carbon dioxide absorption tower 20. On-off valves v10 and v11 are located upstream of the confluence point between the first piping 51 and the recirculating gas piping 53, and upstream of the said confluence point in the recirculating gas piping 53, respectively.

[0027] [Filling material] The packing material filling the vent pipe 24 of the carbon dioxide absorption tower 20 contains particles that have the property of adsorbing carbon dioxide. Hereinafter, these particles will also be referred to as "carbon dioxide adsorbent." This adsorbent is a porous material, and in order to efficiently adsorb carbon dioxide, it is preferable that its pores have a size of 10 Å or less, preferably 8 Å or less, more preferably 6 Å or less, and most preferably 4 Å or less. The carbon dioxide adsorbent may be one type or more, and examples include zeolite, silica, alumina, activated carbon, and MOF. Among these, zeolite or activated carbon is preferred. Examples of zeolites in zeolite particles include aluminophosphate zeolite.

[0028] Aluminophosphate zeolite is a material whose skeletal structure contains at least oxygen, aluminum (Al), and phosphorus (P), and some of these atoms may be substituted with other atoms (Me). Examples of other atoms (Me) include at least one element selected from the group consisting of elements from groups 2A, 3A, 4A, 5A, 7A, 8, 1B, 2B, and groups 3B and 4B other than aluminum in the periodic table. Among these, Me1-aluminophosphate zeolite (hereinafter sometimes referred to as "ALPO"), in which the phosphorus atom is substituted with a heteroatom (Me1: where Me1 is a group 4B element in the periodic table), is preferred.

[0029] Me1 may be present as one type or as two or more types. Preferred Me1 is silicon or germanium, and more preferably silicon. In other words, silicoaluminophosphate zeolite (hereinafter sometimes referred to as "SAPO"), which is an aluminophosphate substituted with silicon, is more preferred.

[0030] The molar ratios of Me1, Al, and P that constitute the ALPO skeletal structure are not particularly limited, but if x1 is the molar ratio of Me1, y1 is the molar ratio of Al, and z1 is the molar ratio of P to the total of Me1, Al, and P, then x1 is usually 0 or greater, preferably 0.01 or greater, and usually 0.3 or less.

[0031] Furthermore, the aforementioned y1 is usually 0.2 or greater, preferably 0.3 or greater, usually 0.6 or less, and preferably 0.5 or less.

[0032] Furthermore, the aforementioned z1 is usually 0.3 or greater, preferably 0.4 or greater, usually 0.6 or less, and preferably 0.5 or less.

[0033] In the present invention, if the zeolite used is SAPO, it is preferable that the relative abundances of aluminum atoms, phosphorus atoms, and silicon atoms in the zeolite satisfy the following formulas (I), (II), and (III). 0.01 ≤ x1 ≤ 0.2 ···(I) (In the formula, x1 represents the molar ratio of silicon to the total amount of silicon, aluminum, and phosphorus in the skeletal structure.) 0.3 ≤ y1 ≤ 0.6 ···(II) (In the formula, y1 represents the molar ratio of aluminum to the total of silicon, aluminum, and phosphorus in the skeletal structure.) 0.3 ≤ z1 ≤ 0.6 ···(III) (In the formula, z1 represents the molar ratio of phosphorus to the total of silicon, aluminum, and phosphorus in the skeletal structure.)

[0034] In other words, when x1 is the relative abundance of silicon atoms, y1 is the relative abundance of aluminum atoms, and z1 is the relative abundance of phosphorus atoms in the skeletal structure of SAPO, it is preferable that the zeolite has a ratio of x1 to 0.01 or more and 0.2 or less, a ratio of y1 to 0.3 or more and 0.6 or less, and a ratio of z1 to 0.3 or more and 0.6 or less.

[0035] Furthermore, x1 is preferably 0.05 or more, more preferably 0.06 or more, even more preferably 0.07 or more, even more preferably 0.075 or more, preferably 0.11 or less, more preferably 0.105 or less, even more preferably 0.100 or less, and even more preferably 0.095 or less.

[0036] Furthermore, the zeolite framework of ALPO in the present invention may contain other elements. Examples of other elements include lithium, magnesium, titanium, zirconium, vanadium, chromium, manganese, iron, cobalt, nickel, palladium, copper, zinc, gallium, germanium, arsenic, tin, calcium, and boron. Preferably, iron, copper, and gallium are included. There may be one or more of these other elements.

[0037] The content of other elements is preferably 0.3 or less, and more preferably 0.1 or less, in terms of the molar ratio of silicon, aluminum, and phosphorus in the zeolite framework.

[0038] The proportions of the above elements are determined by elemental analysis. In this invention, elemental analysis is performed by heating and dissolving the sample in an aqueous hydrochloric acid solution and then using inductively coupled plasma (ICP) emission spectroscopy.

[0039] The ALPO according to the present invention may be any zeolite having a crystal structure defined by IZA (International Zeolite Association), preferably a zeolite having an 8-membered ring in its crystal structure, more preferably AEI type, CHA type, AFX type, or RHO type, and particularly preferably AEI type, CHA type, or AFX type.

[0040] The packing material may contain particles other than the carbon dioxide adsorbent, and may further contain, for example, spacer particles used to adjust the concentration or distribution of the carbon dioxide adsorbent in the packing material. The spacer particles are particles other than the carbon dioxide adsorbent and substantially do not have (or are not expected to have) carbon dioxide adsorption properties. There may be one or more types of spacer particles, and examples include alumina particles. In addition, glass beads, which are commonly used in distillation columns, may also be used as packing materials that do not adsorb carbon dioxide.

[0041] The particle shape of the filler can be appropriately determined within the range in which the effects of this embodiment can be obtained. The particle shape of the filler is preferably spherical from the viewpoint of uniformity of properties and control of porosity.

[0042] The particle size of the filler can be appropriately determined within the range in which the effects of this embodiment can be obtained. The particle size of the filler may be 5 to 100 mm from the viewpoint of uniformity of properties and control of porosity. Preferably, it is 10 to 80 mm, and more preferably, 20 to 50 mm. The particle size of the filler may be any dimension that is appropriate to indicate the size of the filler particle, for example, it may be the major axis or the equivalent circle diameter.

[0043] The packing material is preferably porous from the viewpoint of improving carbon dioxide adsorption characteristics. For example, from the viewpoint of improving contact with carbon dioxide in the gas to be treated (from the viewpoint of improving the carbon dioxide adsorption performance of the carbon dioxide adsorbent), the porosity of the packing material is preferably 10 to 60%. More preferably 20 to 55%, and most preferably 30 to 50%. Also from the same viewpoint, the diameter of the pores (pore size) of the packing material is preferably 10 Å or less, preferably 8 Å or less, more preferably 6 Å or less, and most preferably 4 Å or less. A packing material having the above pore size can constitute a packed layer formed by filling the vent pipe 24 with a porous material having pores of 10 Å or less. The pore size of the packing material can be determined by known methods, such as the mercury intrusion method.

[0044] Furthermore, the filler material may be activated carbon particles as mentioned above, but it may also be biomass-derived. Such filler material can be produced, for example, by a process that includes carbonization of organic matter (biomass) such as bamboo or waste wood. Since carbon dioxide adsorbent can be obtained from biomass that generates carbon dioxide when incinerated, it is preferable for the filler material to be biomass-derived from the viewpoint of achieving a reduction in carbon dioxide in the atmosphere.

[0045] [Heat exchanger] The first piping 51 includes the first heat exchanger 30. The first heat exchanger 30 has heat medium piping through which a heat medium flows, and the first heat exchanger 30 has connection nozzles H5 and H6 for the heat medium piping on the upstream and downstream sides, respectively.

[0046] Similarly, the recirculating gas piping 53 also includes the second heat exchanger 40. The second heat exchanger 40 also has heat transfer piping through which a heat transfer medium flows, and the upstream and downstream sides of the second heat exchanger 40 have connection nozzles H7 and H8 for the heat transfer piping.

[0047] Figure 4 schematically shows the configurations of the first heat exchanger 30 and the second heat exchanger 40. Although the first heat exchanger 30 is shown, the second heat exchanger 40 has a similar configuration to the first heat exchanger. The first heat exchanger 30 is configured similarly to the dehumidification tower 10, except that the tower body 11 is an airtight container 31. The container 31 is connected to the first piping 51 at both ends. The heat transfer medium piping 32 is connected to a connecting nozzle H5 at one end and to a connecting nozzle H6 at the other end, and extends inside the container 31 in a meandering manner from one end to the other, passing through multiple heat dissipation plates that make up the fins 33.

[0048] [Removal of carbon dioxide from gas] An example of a method for recovering carbon dioxide from the atmosphere using a carbon dioxide recovery system according to one embodiment of the present invention is described. This embodiment is realized by adjusting the temperature of the gas to be treated with a heat transfer medium, and the recovery of carbon dioxide in this embodiment is achieved by the steps of dehumidification, heating, adsorption, and concentration.

[0049] [Heat transfer fluid] In embodiments of the present invention, the heat transfer medium can be appropriately selected within a range that makes it feasible for the gas to be processed to be moved by cooling. In this specification, the heat transfer medium for cooling the gas to be processed is also referred to as a "refrigerant." From the viewpoint of effectively utilizing the cold energy of the fluid, the heat transfer medium is preferably a liquefied gas. Generally, liquefied gases are cooled and transported as a liquid during transport, and then heated and used as a gas. In embodiments of the present invention, by appropriately designing the layout of the flow path for the liquefied gas in equipment that vaporizes and handles the liquefied gas, it is possible to effectively utilize the cold energy of such liquefied gas.

[0050] Examples of liquefied gases include liquefied natural gas and liquid hydrogen. The boiling point of liquefied natural gas is an extremely low -162°C, and the boiling point of liquid hydrogen is an extremely low -253°C. Therefore, these liquefied gases are suitable from the viewpoint of significantly reducing the density of the gas to be treated by cooling, and are suitable from the viewpoint of promoting the movement (flow) of the gas to be treated by cooling.

[0051] [Dehumidification process] Liquid natural gas at -162°C is supplied as a refrigerant to the connecting nozzle H1 of the dehumidification tower 10. The liquefied natural gas passes through the heat transfer fluid piping 12 and is discharged from the connecting nozzle H2. The on-off valves v1 and v2 are open, and the on-off valve v3 is closed.

[0052] The supply of the refrigerant described above cools the heat transfer fluid pipes 12 and fins 13, and the cooling is particularly strong at the bottom of the tower body 11. The air inside the dehumidification tower 10 is cooled by the heat transfer fluid pipes 12 and fins 13, and the cooled air moves further downward due to the density difference before and after cooling. Since the tower body 11 is open at the top, as the air inside the tower is cooled and moves downward, outside air from outside the tower is supplied into the tower body 11 through the opening 14.

[0053] Furthermore, as cooling occurs within the tower body 11, the dew point of the air inside the tower decreases, and the moisture in the air condenses or freezes on the surfaces of the heat transfer fluid pipes 12 and fins 13. The air inside the tower is cooled to approximately -162°C at the lower part of the tower body 11. Therefore, the air flowing down the dehumidification tower 10 is dehumidified. However, the concentration of carbon dioxide in the air remains substantially unchanged before and after cooling. In this way, by allowing the air to flow down the dehumidification tower 10 naturally, dry air with, for example, a dew point of -100°C, a temperature of -140°C, and a carbon dioxide concentration of 400 ppm is produced.

[0054] In this way, the dehumidification tower 10 cools the air and transports it downwards, and the dehumidification tower 10 also acts as an air transport device that moves the air to be treated, which is the air supply source (outside air), from top to bottom within the tower body 11. The tower body 11 has a pipe structure in which its upper end is open to the outside air when installed vertically, and the heat transfer fluid pipes 12 and fins 13 are cooling sections that make the temperature inside the tower body 11 lower as it goes down, and they constitute a heat exchanger located inside the tower body 11 into which the refrigerant is supplied from bottom to top.

[0055] <Regarding air movement due to temperature changes> Such air movement due to temperature changes can be achieved by making the temperature at the bottom lower than the temperature at the top in a pipe structure through which air flows. From the viewpoint of realizing air flow due to temperature changes, it is preferable that the temperature at the bottom of the pipe structure (bottom temperature) is 30°C or more lower than the temperature at the top of the pipe structure (top temperature). From the viewpoint of promoting air flow, it is more preferable that the bottom temperature is 60°C or more lower than the top temperature, and even more preferable that it is 100°C or more lower. The top temperature is the temperature at a position 5 cm from the top end of the pipe structure, and the bottom temperature is the temperature at a position 5 cm from the bottom end of the pipe structure.

[0056] From the viewpoint of promoting airflow, it is preferable to keep the lower temperature sufficiently low. From this viewpoint, the lower temperature is preferably -70°C or lower, more preferably -100°C or lower, and even more preferably -120°C or lower. From the viewpoint of promoting airflow, a lower temperature is preferable, but from the viewpoint of suppressing the cost or complexity of equipment required to maintain the cryogenic state of the heat transfer medium, the lower temperature is preferably -253°C or higher, more preferably -200°C or higher, and even more preferably -163°C or higher.

[0057] Furthermore, if the temperature gradient between the upper and lower parts of the above-mentioned pipe structure is too large, the cooling of the air by the cooling unit may be insufficient depending on the contact between the air and the cooling unit, and if it is too small, the air flow may be slow. From the viewpoint of promoting the air flow, the above-mentioned temperature gradient is preferably 50°C / m or more, more preferably 60°C / m or more, and even more preferably 70°C / m or more. Also, from the viewpoint of sufficiently enhancing the cooling effect of the cooling unit on the air, the above-mentioned temperature gradient is preferably 200°C / m or less, more preferably 180°C / m or less, and even more preferably 150°C / m or less. This temperature gradient can be adjusted by the contact between the cooling unit and the air (for example, by increasing or decreasing the surface area of ​​the cooling unit).

[0058] Furthermore, if the voids in the above-mentioned pipe structure are too large, contact between the air and the cooling section may be insufficient, resulting in inadequate cooling of the air by the cooling section. If they are too small, the air flow may be slow. From the viewpoint of sufficiently enhancing the cooling effect of the air by the cooling section, the voids are preferably 70% or less, more preferably 60% or less, and even more preferably 50% or less. Also, from the viewpoint of promoting the air flow, the voids are preferably 25% or more, more preferably 30% or more, and even more preferably 35% or more. Note that the voids are the ratio of the total volume of the solid phase to the total volume of the gas phase in the above-mentioned pipe structure.

[0059] For example, more specifically in this embodiment, in the dehumidification tower 10, the dew point of the dry air can be adjusted by the height dimension between the heat transfer medium pipe 12 and the fins 13. Also, for example, in the dehumidification tower 10, the resistance of air movement within the tower body 11 can be adjusted by the pitch of the fins 13.

[0060] [Heating process] The dry air generated in the dehumidification tower 10 reaches the first heat exchanger 30 through the first piping 51 and is heated by the first heat exchanger 30. A sufficiently high temperature, for example 100°C, liquefied natural gas is supplied as a heat transfer medium from the connecting nozzle H5 in the first heat exchanger 30. This heat transfer medium is cooled to an appropriate temperature, for example 50°C, as it passes through the first heat exchanger 30 and is discharged from the connecting nozzle H6. The on-off valve v10 is open. The dry air flows from the upstream side to the downstream side within the first heat exchanger 30 as the air cools and flows down in the carbon dioxide absorption tower 20 downstream of the first heat exchanger 30, which will be described later.

[0061] The dry air with a dew point of -100°C, a temperature of -140°C, and a carbon dioxide concentration of 400 ppm passes through the container 31 of the first heat exchanger 30 while in contact with the heat transfer piping 32 and the fins 33. Liquefied natural gas at the above temperature flows through the heat transfer piping 32, and the heat transfer piping 32 and the fins 33 are heated to several tens of degrees Celsius. Therefore, the dry air flowing through the container 31 while in contact with the heat transfer piping 32 and the fins 33 is heated. In this way, the first heat exchanger 30 generates dry air with a dew point of -100°C, a carbon dioxide concentration of 400 ppm, and a temperature of 0°C.

[0062] [Adsorption process] The dry air heated in the first heat exchanger 30, with a dew point of -100°C, a temperature of 0°C, and a carbon dioxide concentration of 400 ppm, reaches the carbon dioxide absorption tower 20 through the first piping 51, where the carbon dioxide in the dry air is adsorbed. Liquid liquefied natural gas at -162°C is supplied as a refrigerant from the connecting nozzle H3 in the carbon dioxide absorption tower 20, passes through the heat transfer fluid flow section 27, and is discharged from the connecting nozzle H4. The on-off valves v4, v5, v7, and v9 are open, and the on-off valves v6 and v8 are closed, and the carbon dioxide absorption tower 20 is connected to the first gas tank 72 downstream.

[0063] As a result of the refrigerant supply described above, a lower temperature refrigerant is supplied to the heat medium circulation section 27 from below. This refrigerant cools the vent pipe 24 from below as it reaches the top of the heat medium circulation section 27 and is discharged from the carbon dioxide absorption tower 20 via the connecting nozzle H4. This cooling by the refrigerant cools the vent pipe 24 and the packing material filled inside it (the entire packing material inside the vent pipe 24 is also called the "packed bed") more strongly at the bottom.

[0064] As a result, the dry air inside the vent pipe 24 is cooled, and due to the density difference before and after cooling, the cooled air moves further downward. The vent pipe 24 is connected to the upper vent section 25 and the lower vent section 26, and the vent section 25 is connected to the first pipe 51. Therefore, as the dry air inside the vent pipe 24 is cooled and moves downward, the dry air from the vent section 25 is supplied into the vent pipe 24, and the dry air from the first pipe 51 is supplied to the vent section 25.

[0065] Furthermore, the dry air flowing down the vent pipe 24 comes into contact with the packing material, and the carbon dioxide in the dry air is adsorbed onto the packing material (carbon dioxide packing material) by physical adsorption.

[0066] In this way, the dry air is cooled again as it flows naturally down the vent pipe 24, and the carbon dioxide in the dry air is adsorbed onto the packing material and removed from the dry air. Thus, carbon dioxide-free dry air with a dew point of -100°C, a temperature of -140°C, and 0 ppm of carbon dioxide is produced. The carbon dioxide-free dry air is stored in the first gas tank 72 via the vent section 26 and the second pipe 52. The first gas tank 72 stores the amount of carbon dioxide-free dry air required for the concentration process described later, and the remaining carbon dioxide-free dry air is released to the outside, for example, into the atmosphere. The amount of carbon dioxide-free dry air required for the concentration process can be appropriately determined according to the desired concentration ratio. For example, when concentrating carbon dioxide to 50,000 ppm, the amount is 1 / 125th of the total amount of dry air that saturated the carbon dioxide absorption tower 20.

[0067] Thus, the carbon dioxide absorption tower 20 includes a heat transfer fluid section that lowers the temperature inside the vent pipe 24 as it goes down during the adsorption process, and is a gas transport device that moves the heated dry air from the first pipe 51 from top to bottom inside the vent pipe 24.

[0068] Furthermore, the carbon dioxide absorption tower 20 is a carbon dioxide adsorption device that, in the adsorption process, includes a vent pipe 24 extending vertically with its upper end open to a dry air supply source, a permeable adsorption layer (packed bed) for adsorbing carbon dioxide housed within the vent pipe 24, and a heat transfer medium flow section 27 that covers the outer surface of the vent pipe 24 and supplies liquefied gas as a refrigerant from below to above outside the vent pipe 24, and dry air is supplied to the vent pipe 24 from above, and carbon dioxide in the dry air is adsorbed onto the adsorption layer.

[0069] The end of the adsorption process in the carbon dioxide absorption tower 20 is determined by the concentration of carbon dioxide in the dry air flowing down from the carbon dioxide absorption tower 20. That is, when the concentration of carbon dioxide in the dry air flowing down from the carbon dioxide absorption tower 20 reaches a predetermined concentration greater than 0 ppm (for example, 10 ppm), it can be determined that the carbon dioxide has saturated the adsorbent, and the adsorption process by each carbon dioxide absorption tower 20 has ended. The carbon dioxide absorption tower 20 that has completed the adsorption process is then subjected to the concentration process.

[0070] [Concentration process] In the concentration process, the carbon dioxide adsorbed by the packing material of the vent pipe 24 is released into the carbon dioxide-free dry air by passing the aforementioned carbon dioxide-free dry air through the vent pipe 24. During the concentration process, the first gas tank 72, the second heat exchanger 40, the carbon dioxide absorption tower 20, and the second gas tank 73 are connected. That is, the shut-off valves v10, v5, and v7 are closed, and the shut-off valves v8, v11, v4, and v6 are open. In addition, the supply of refrigerant to the carbon dioxide absorption tower 20 is stopped. Thus, the carbon dioxide absorption tower 20 further includes shut-off valves v10 and v11 that switch the airflow path to the vent pipe 24 so that the upper end of the vent pipe 24 is open to the supply source of carbon dioxide-free heated dry air during the concentration process.

[0071] The carbon dioxide-free dry air contained in the first gas tank 72 reaches the second heat exchanger 40 through the reflux gas piping 53 and is heated by the second heat exchanger 40. Liquefied natural gas at a sufficiently high temperature, for example 100°C, is supplied as a heat transfer medium from the connecting nozzle H7 in the second heat exchanger 40. This heat transfer medium is cooled to a suitable temperature, for example 50°C, as it passes through the second heat exchanger 40 and is discharged from the connecting nozzle H8. The carbon dioxide-free dry air is heated by contacting the heat transfer medium piping 42 and fins 43 as it passes through the second heat exchanger 40. In this way, the second heat exchanger 40 produces dry air with a dew point of -100°C, a carbon dioxide concentration of 0 ppm, and a temperature of 50°C.

[0072] The dry air described above flows from upstream to downstream within the second heat exchanger 40 as the air cools and flows down in the carbon dioxide absorption tower 20 downstream of the second heat exchanger 40, which will be described later. In other words, since a refrigerant was supplied to the heat medium flow section 27 in the carbon dioxide absorption tower 20, the vent pipe 24 and the packed bed inside it are cooled more strongly at the bottom. Therefore, the dry air inside the vent pipe 24 moves further down due to the density difference caused by the cooling, and as a result, dry air upstream of the vent pipe 24 is introduced into the vent pipe 24. Thus, in the concentration process, the permeable layer including the vent pipe 24 and the packed bed inside it, which are cooled to a lower temperature at the bottom in the carbon dioxide absorption tower 20, acts as a cooling section that cools the dry air (gas to be treated) inside the vent pipe 24. Therefore, in the concentration process as well, the carbon dioxide absorption tower 20 includes a vent pipe 24 whose upper end is open to a source of heated, dry, carbon dioxide-free air when installed vertically, and a cooling section that lowers the temperature inside the vent pipe 24 as it goes down, and is a gas transport device that moves the dry air from the source from top to bottom inside the vent pipe 24. The cooling section is a permeable layer inside the vent pipe 24, where the temperature at the bottom is lower than the temperature at the top.

[0073] As heated, carbon dioxide-free dry air flows down through the vent pipe 24 due to its temperature, the packing material that has adsorbed carbon dioxide to a saturation concentration in the vent pipe 24 comes into contact with the heated, carbon dioxide-free dry air and is heated by the dry air. As a result, the carbon dioxide adsorbed by the adsorbing material is released from the packing material. In this way, by flowing a sufficiently small amount of carbon dioxide-free dry air, compared to the dry air used for carbon dioxide adsorption, down through the vent pipe 24 as described above and bringing it into contact with the adsorbing material after carbon dioxide adsorption, dry air containing carbon dioxide at a sufficiently higher concentration than before the adsorption process (for example, 50,000 ppm compared to 400 ppm) is generated (hereinafter also referred to as "carbon dioxide-concentrated dry air").

[0074] The gas flowing through pipe 20 to desorb carbon dioxide from the adsorbent that has adsorbed the carbon dioxide in the concentration process described above is preferably carbon dioxide-free dry air, as described above. However, dry air containing carbon dioxide (approximately 400 ppm) is also acceptable, although its desorption performance is slightly inferior. In this case as well, as with the case of carbon dioxide-free dry air described above, low-temperature dry air dehumidified in the dehumidification tower 10 and heated to a predetermined temperature by a heat exchanger can be used. Therefore, the dry air in the first pipe 51 can be used directly for carbon dioxide desorption.

[0075] The carbon dioxide-concentrated dry air generated in the carbon dioxide absorption tower 20 is stored in the second gas tank 73 via the concentrated gas piping 54. The carbon dioxide-concentrated dry air stored in the second gas tank 73 is supplied to the next process as needed. For example, the carbon dioxide-concentrated dry air can be supplied as a raw material gas for carbon dioxide in a process to produce synthetic fuel by reacting carbon dioxide with hydrogen. Alternatively, the carbon dioxide-concentrated dry air can be supplied, diluted to an appropriate concentration as needed, as an atmospheric gas to promote photosynthesis and growth of plants such as crops in a cultivation process.

[0076] The carbon dioxide-concentrated dry air produced in this way can be further concentrated by means other than those described above. The several percent carbon dioxide-concentrated dry air obtained by this method can be concentrated to a desired concentration by known methods such as absorbent liquids, solid adsorbents, and gas separation membranes. In this case, it is preferable to again utilize unused cold energy or unused waste heat, as this allows for the concentration of trace amounts of carbon dioxide in the air to the high concentrations commonly used in CCS or CCU, while significantly reducing the amount of energy newly input.

[0077] [Water production process] In the dehumidification tower 10, the ice formed on the surface of the heat transfer medium pipe 12 and fins 13 can be melted by heating the heat transfer medium pipe 12 and fins 13 and recovered as water. During this water production process, the dehumidification tower 10 is connected to the water storage tank 71. That is, valves v1 and v3 are opened, and valve v2 is closed.

[0078] In the water production process, liquefied natural gas at a sufficiently high temperature, for example 100°C, is supplied as a heat transfer medium from the connecting nozzle H1 in the dehumidification tower 10. The supply of this heat transfer medium heats the heat transfer medium piping 12 and fins 13, melting the ice covering their surfaces and causing it to flow down as water. The heat transfer medium is cooled to a suitable temperature, for example 50°C, as it passes through the heat transfer medium piping 12, and is discharged from the connecting nozzle H2. The water that has flowed down from the heat transfer medium piping 12 and fins 13 flows out of the tower body 11 and is stored in the water storage tank 71 through the drain pipe 55. The water stored in the water storage tank 71 is treated with ion exchange resin or the like as needed and used as drinking water. The dehumidification tower 10, from which the ice has been removed from the surfaces of the heat transfer medium piping 12 and fins 13, is then used again for the generation of dry air as described above.

[0079] Thus, in this embodiment, the dehumidification tower 10 can also function as a water purification device, comprising a tower body 11 that is a vertically extending pipe structure with its upper end open to the atmosphere, and a heat transfer medium pipe 12 and fins 13 arranged inside the tower body 11, to which liquefied gas is supplied from below to above as a refrigerant, and configured to recover water from the air adhering to the heat transfer medium pipe 12 and fins 13.

[0080] [Overall structural characteristics] As is clear from the above description, the carbon dioxide recovery system 1 of this embodiment includes a dehumidifying tower 10 which can also function as a water desalination device, and a carbon dioxide absorption tower 20 to which the dry air generated in the dehumidifying tower 10 is supplied from above to a vent pipe 24, and recovers carbon dioxide from the air. The carbon dioxide recovery system 1 of this embodiment is suitable from the viewpoint of suppressing a decrease in the heat exchange efficiency of the dehumidifying tower 10 and from the viewpoint of being able to recover water from the atmosphere.

[0081] Furthermore, in the carbon dioxide recovery system 1, liquid liquefied gas is supplied as a refrigerant to the dehumidification tower 10 during the dehumidification process and to the carbon dioxide absorption tower 20 during the adsorption process. This refrigerant is heated by heat exchange with outside air or dry air in the dehumidification tower 10 or carbon dioxide absorption tower 20 to become a gas, which is then discharged from the dehumidification tower 10 or carbon dioxide absorption tower 20. Thus, the heat transfer medium piping 12 and fins 13 in the dehumidification tower 10, and the heat transfer medium flow section 27 in the carbon dioxide absorption tower 20, each also function as a vaporizer for vaporizing the liquid liquefied gas. The carbon dioxide recovery system 1 may be installed in conjunction with equipment that vaporizes and handles liquefied gas, and by appropriately designing the flow path layout of the liquefied gas in the equipment, the cooling energy of the liquefied gas in the equipment can be effectively utilized, and the system can also function as a vaporizer for the liquefied gas in the equipment.

[0082] [Main effects and benefits] In this embodiment, the cold energy of liquefied gas is used to cool the gas to be treated (outside air or dry air) in the carbon dioxide recovery system 1. The cooled gas to be treated sinks and becomes heavier as it cools further, causing it to flow downstream. The cooled gas to be treated pushes the gas downstream at the point where it flows, and the gas from the upstream side is drawn into the space left behind. In this embodiment, by utilizing this flow of the gas to be treated, the movement of the gas to be treated from the upstream side to the downstream side in the carbon dioxide recovery system 1 is achieved without using blowers such as fans. This flow of the gas to be treated can be achieved by configuring the dehumidification tower 10 and the carbon dioxide absorption tower 20 so that the gas to be treated is cooled more at the bottom during the cooling process.

[0083] Furthermore, as described above, this invention can operate without the use of a fan or other blower, but a fan may be used to further increase efficiency. Even in that case, since gas movement due to the temperature difference can be utilized, a significant energy-saving effect can be expected.

[0084] In this embodiment, as described above, no energy is required to generate an external force to move the gas to be treated, and the movement of the gas to be treated is achieved by utilizing the cold energy of the liquid liquefied gas. Therefore, this embodiment is suitable from the viewpoint of saving labor in carbon dioxide concentration, and from the viewpoint of reducing running costs and product costs as a result.

[0085] Furthermore, in this embodiment, by switching the heat transfer medium supplied to the dehumidification tower 10 from a refrigerant to a heat transfer medium, it is possible to recover water from the ice generated together with the dry air in the dehumidification tower 10. Thus, in this embodiment, the dehumidification tower 10 can also be used as a water production device.

[0086] Furthermore, in this embodiment, since carbon dioxide is absorbed from dry air, the decrease in the adsorption characteristics of the adsorbent is suppressed. Adsorbents that have adsorption characteristics for carbon dioxide generally exhibit stronger adsorption characteristics for water. In this embodiment, since carbon dioxide is separated by adsorption from dry air that contains carbon dioxide but is substantially free of water, this embodiment is suitable from the viewpoint of suppressing the decrease in the adsorption capacity of the adsorbent due to water adsorption.

[0087] [Other Embodiments] The dehumidification tower 10, the first heat exchanger 30, and the second heat exchanger 40 may all be heat exchangers other than fin-tube type heat exchangers, for example, coil type heat exchangers.

[0088] The carbon dioxide absorption tower 20 may have a configuration other than a core-shell type multitube reactor, and may have a configuration such as a multi-plate reactor capable of cooling multiple vents into which packing material can be filled.

[0089] In the embodiments of the present invention, the gas to be treated does not have to be air, as long as it is a gas containing carbon dioxide to be adsorbed. The gas to be treated may be a gas that contains carbon dioxide at a sufficiently high concentration compared to the atmosphere, such as exhaust gas from an incinerator or combustion furnace.

[0090] The carbon dioxide recovery system 1 may have another configuration capable of heating the gas to be treated, instead of the first heat exchanger 30 and the second heat exchanger 40. For example, the steam in the steam piping of the liquefied gas handling equipment may be used as the heat transfer medium. Alternatively, the first or third piping may be laid out so that a portion of it passes outside (in the atmosphere, underground, underwater, etc.), thereby enabling the dry air to be heated to a suitable temperature by outside air, water from the sea, lakes, or rivers, geothermal energy, or solar heat.

[0091] In the water production process, instead of supplying a refrigerant and circulating a heat transfer medium, the supply of the heat transfer medium may be stopped, and outside air at a sufficiently high temperature, close to room temperature, may be supplied to the dehumidification tower 10 to melt the ice covering the surfaces of the heat transfer medium piping 12 and fins 13.

[0092] In the above-described embodiment, a carbon dioxide recovery system 1 having one dehumidifying tower 10 and one carbon dioxide absorption tower 20 was shown. However, in the embodiment of the present invention, the dehumidifying tower 10 and the carbon dioxide absorption tower 20 each consist of multiple towers arranged side by side, these towers are connected in parallel by piping, and on-off valves for opening and closing the piping are appropriately arranged so that the tower can be connected to any of the multiple towers.

[0093] Furthermore, although the embodiments described above do not include a blower, in the embodiments of the present invention, a blower may be placed in the flow path of the gas to be treated as needed. Such a configuration is advantageous from the viewpoint of improving the work efficiency in carbon dioxide recovery and concentration.

[0094] According to embodiments of the present invention, it is possible to recover and concentrate carbon dioxide regardless of its concentration in the target gas, and it is also effective in reducing the amount of carbon dioxide in the environment. Furthermore, according to embodiments of the present invention, the cold energy of the liquefied gas used after vaporization can be effectively utilized, and the series of processes for carbon dioxide recovery can be realized without the use of a blower, thus it is superior from the viewpoint of labor saving. The present invention, including such embodiments, is expected to contribute to achieving, for example, Goal 9 of the Sustainable Development Goals (SDGs) advocated by the United Nations, "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation."

[0095] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0096] 1. Carbon dioxide capture system 10 Dehumidification tower (water generation device) 11 Tower body 12, 32, 42 Heat medium piping 13, 33, 43 Finn 14 Opening 20. Carbon dioxide absorption tower (carbon dioxide adsorption device) 21 Shell body 22, 23 Partition plates 24. Ventilator 25, 26 Ventilation section 27 Heat medium flow section 30 First heat exchanger 31, 41 container 40 Second heat exchanger 51 First Piping 52 Second piping 53 Recirculating gas piping 54 Concentrated gas piping 55 Drain pipe 71 Water storage tank 72 First Gas Tank 73 Second gas tank H1~H8 Connection Nozzles v1~v11 Shut-off valves

Claims

1. A pipe whose upper end is open to the source of the gas to be treated when installed vertically, A cooling unit that lowers the temperature inside the pipe as it goes down, A gas conveying device that moves the gas to be treated from the supply source, including the gas, from top to bottom within the pipe.

2. The gas conveying apparatus according to claim 1, wherein the temperature in the lower part of the pipe is 30°C or more lower than the temperature in the upper part of the pipe.

3. The gas conveying device according to claim 1, wherein the degree of voids in the pipe is 70% or less and 25% or more.

4. The gas conveying apparatus according to claim 1, wherein the temperature in the lower part of the pipe is between -70°C and -253°C.

5. The gas conveying apparatus according to claim 1, wherein the temperature gradient between the upper and lower parts of the pipe is 50°C / m or more and 200°C / m or less.

6. The gas transport device according to claim 1, wherein the cooling unit is a heat exchanger located inside the pipe and supplied with a refrigerant from bottom to top.

7. The gas transport device according to claim 1, wherein the cooling section has an outer shell structure that covers the outer surface of the pipe and supplies a refrigerant from bottom to top on the outside of the pipe.

8. The gas transport apparatus according to claim 1, wherein the cooling section is a permeable layer housed within the pipe, the lower part of which is at a lower temperature than the upper part.

9. The gas transport apparatus according to claim 1, further comprising a permeable adsorption layer for adsorbing carbon dioxide inside the pipe.

10. The gas transport apparatus according to claim 9, wherein the adsorption layer is a packed layer formed by filling the tube with a porous material having pores of 10 Å or less.

11. The gas transport apparatus according to claim 6 or 7, wherein the refrigerant is a liquefied gas.

12. The gas conveying apparatus according to claim 11, wherein the liquefied gas is liquefied natural gas.

13. The gas transport apparatus according to claim 11, wherein the liquefied gas is liquid hydrogen.

14. The gas conveying apparatus according to claim 1, wherein the gas to be processed is air.

15. A pipe that extends vertically, and whose upper end is open to the atmosphere, The pipe is located inside the heat exchanger, which is supplied with liquefied gas as a refrigerant from bottom to top. A water desalination apparatus configured to recover water from the air adhering to the heat exchanger.

16. A pipe extending vertically, the upper end of which is open to a source of dehumidified air, A permeable adsorption layer that adsorbs carbon dioxide is housed inside the aforementioned pipe, It has an outer shell structure that covers the outer surface of the pipe and on the outside of the pipe, from bottom to top, a liquefied gas is supplied as a refrigerant. A carbon dioxide adsorption device in which dehumidified air is supplied to the pipe from above, and carbon dioxide in the air is adsorbed onto the adsorption layer.

17. The carbon dioxide adsorption apparatus according to claim 16, further comprising a flow path switching device for switching the airflow path to the pipe such that the upper end of the pipe is open to a supply source of air that is dehumidified, has carbon dioxide removed, and has a temperature above the temperature at which the adsorption layer desorbs carbon dioxide.

18. The water production apparatus according to claim 15, The carbon dioxide adsorption apparatus according to claim 17, wherein the dehumidified air produced by the water desalination apparatus is supplied to the pipe from above, A carbon dioxide capture system that recovers carbon dioxide from the air.

19. The carbon dioxide recovery system according to claim 18, wherein one or both of the heat exchanger and the outer shell structure also serve as a vaporizer for vaporizing the liquid liquefied gas in a liquefied gas processing device for vaporizing the liquid liquefied gas.

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