Carbon Dioxide Fixation System

Abstract

To provide a carbon dioxide fixing system which can effectively use power of a turbine.SOLUTION: A carbon dioxide fixing system 1 includes a compression device 27 for compressing gaseous carbon dioxide. The carbon dioxide fixing system 1 includes a cooler 50 for cooling the carbon dioxide fed from the compression device 27, and liquefying the carbon dioxide. The carbon dioxide fixing system 1 includes a reactor 80 for reacting a substance containing carbon dioxide supplied from the cooler 50 and at least any one of alkali metal and alkaline-earth metal, with water, thereby generating carbonate.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a carbon dioxide fixation system. [Background technology]

[0002] Carbon dioxide is considered a problem as a cause of global warming, and efforts to curb carbon dioxide emissions are gaining momentum worldwide. One method proposed for reducing carbon dioxide emissions into the atmosphere is to fix carbon dioxide as carbonates.

[0003] As such a method, Patent Document 1 discloses a carbon dioxide mineral fixation system that can maximize the elution of magnesium and other elements in rocks such as serpentine at a relatively low temperature and convert them into stable carbonates. The mineral fixation system includes a pressure pump that pressurizes carbon dioxide, a pressure vessel that heats and pressurizes the pressurized carbon dioxide and minerals in the presence of water to cause a reaction, a pressure-maintaining valve that controls the pressure of the fluid discharged from the pressure vessel, and a gas-liquid separator that separates the fluid that has flowed through the pressure-maintaining valve. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-240855 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the above mineral fixation system, for example, in the case of serpentine, the fixation rate of carbon dioxide is maximum under the conditions of a temperature of 100°C and a pressure of 10 MPa. However, when carbon dioxide is compressed to such a high pressure using a compression device such as a pressure pump, a large amount of energy is required to operate the pressure pump. In addition, the pressure pump needs to be regularly maintained just to produce carbonate from carbon dioxide. In order to fix a large amount of carbon dioxide, the reaction scale needs to be enlarged, and there is a risk that carbon dioxide cannot be fixed efficiently with conventional systems.

[0006] Therefore, an object of the present disclosure is to provide a carbon dioxide fixation system that can produce carbonate without using a dedicated compression device. [Means for solving the problem]

[0007] The carbon dioxide fixation system according to the present disclosure includes a compressor that compresses gaseous carbon dioxide. The carbon dioxide fixation system includes a cooling device that cools the carbon dioxide sent from the compressor to liquefy the carbon dioxide. The carbon dioxide fixation system includes a reaction device that reacts the carbon dioxide supplied from the cooling device with a substance containing at least one of an alkali metal and an alkaline earth metal, and water to produce a carbonate.

[0008] The carbon dioxide fixation system may further include an oxygen separation section that separates oxygen from air, and a boiler that burns fuel with the oxygen separated by the oxygen separation section to generate gaseous carbon dioxide to be supplied to the compression device. The reaction device may be heated by steam generated by the boiler. The carbon dioxide fixation system may further include a heat exchanger that exchanges heat of the carbon dioxide compressed by the compression device with heat of the carbon dioxide flowing from the cooling device to the reaction device. The alkali metal may be at least one element selected from the group consisting of lithium, sodium, and potassium. The alkaline earth metal may be at least one element of calcium and magnesium. Effect of the Invention

[0009] According to the present disclosure, it is possible to provide a carbon dioxide fixation system capable of producing carbonate without using a dedicated compression device. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram illustrating a carbon dioxide fixation system according to one embodiment. [Diagram 2] 1 is a schematic diagram showing an oxyfuel power generation apparatus according to an embodiment; [Diagram 3] FIG. 2 is a schematic diagram showing details of a carbon dioxide fixation system according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, some exemplary embodiments will be described with reference to the drawings. Note that the dimensional ratios of the drawings are exaggerated for the convenience of explanation and may differ from the actual ratios.

[0012] As shown in FIG. 1, the carbon dioxide fixation system 1 includes an oxyfuel combustion power generation apparatus 10, a carbon dioxide capture apparatus 20, a water supply apparatus 60, a raw material supply apparatus 70, and a reaction apparatus 80.

[0013] The oxyfuel combustion power generation apparatus 10 generates power by burning oxygen. As shown in Fig. 2, the oxyfuel combustion power generation apparatus 10 includes a fuel supply unit 11, an oxygen separation unit 12, a boiler 13, and a dust collector 14.

[0014] The fuel supply unit 11 supplies fuel to the boiler 13. The fuel supplied to the boiler 13 is not particularly limited, and examples thereof include coal, oil, and natural gas. Among these, the fuel is preferably coal from the viewpoints of low cost and stable supply. When coal is used as the fuel, it is preferable to crush the coal into a size suitable for fuel using a coal crushing mill or the like, and supply the crushed coal to the boiler 13.

[0015] The oxygen separation unit 12 separates oxygen from air. The oxygen separation unit 12 removes nitrogen from air by, for example, cryogenic separation or pressure swing. The oxygen separation unit 12 produces oxygen at preferably 90 mol % or more, more preferably 95 mol % or more. The oxygen separated by the oxygen separation unit 12 is supplied to a boiler 13.

[0016] Boiler 13 burns fuel with oxygen separated by oxygen separation unit 12. Fuel is supplied from fuel supply unit 11. Water is vaporized to steam by energy obtained by burning fuel, and the steam rotates a turbine (not shown), which causes a generator connected to the turbine to generate electricity. Meanwhile, boiler 13 burns fuel in an oxygen atmosphere to generate gaseous carbon dioxide to be supplied to compression device 27, which will be described later. Water is also generated by burning fuel in boiler 13.

[0017] The dust collector 14 removes foreign matter such as dust from the gas generated by combustion in the boiler 13. The gas from which foreign matter has been removed by the dust collector 14 is supplied to the carbon dioxide capture device 20. A portion of the gas from which foreign matter has been removed by the dust collector 14 may be recirculated by being supplied again to the boiler 13. Since the main component of the above gas is carbon dioxide, supplying the above gas to the boiler 13 reduces the combustion temperature of the boiler 13 and reduces the load on the boiler 13.

[0018] In the oxyfuel combustion power generation system 10, nitrogen is removed from the air by the oxygen separation section 12 to separate oxygen, and the boiler 13 uses this oxygen as combustion gas to burn fuel. The main components of the gas discharged from the boiler 13 are carbon dioxide and water, which can be easily separated. Therefore, carbon dioxide can be easily collected compared to the case where fuel is burned using air as combustion gas.

[0019] The carbon dioxide capture unit 20 is provided downstream of the oxyfuel combustion power generation plant 10. The carbon dioxide capture unit 20 purifies and liquefies the carbon dioxide supplied from the oxyfuel combustion power generation plant 10, thereby capturing the carbon dioxide generated in the oxyfuel combustion power generation plant 10. As shown in Fig. 3, the carbon dioxide capture unit 20 includes a scrubber 21, a compressor 27, a heat exchanger 29, a cooler 30, a dryer 40, and a cooling unit 50.

[0020] The scrubber 21 removes sulfur components from the gas generated in the oxyfuel combustion power generation system 10. By removing the sulfur components in the gas, corrosion of the compressor 27 can be suppressed. The scrubber 21 is, for example, a wet-type desulfurization device, but hydrogen chloride in the gas can also be removed. The scrubber 21 may be a dry-type desulfurization device. The scrubber 21 includes an absorption tower 22, a filler 23, a circulation pipe 24, and a circulation pump 25.

[0021] The absorption tower 22 is provided with a packing material 23 inside. A circulation pipe 24 is connected to the bottom of the absorption tower 22 below the packing material 23 and the upper side of the packing material 23. A circulation pump 25 is provided to the circulation pipe 24. The absorption tower 22 contains a treatment liquid, and the treatment liquid is pumped up to the upper side of the packing material 23 through the circulation pipe 24 by the circulation pump 25. The treatment liquid is sprayed from the upper side of the packing material 23 toward the packing material 23 and falls from the packing material 23 to the bottom of the absorption tower 22. Meanwhile, the absorption tower 22 is provided with a supply port below the packing material 23 through which the gas generated in the oxygen combustion power generation device 10 is supplied. In addition, the absorption tower 22 is provided with an exhaust port above the packing material 23 for discharging the gas supplied from the supply port. The gas supplied from the supply port passes through the packing material 23, and sulfur oxides are removed from the gas by gas-liquid contact with the treatment liquid, and the gas is discharged from the exhaust port.

[0022] The treatment liquid of the scrubber 21 is not particularly limited as long as it can remove sulfur oxides, but may be water or an aqueous solution of sodium hydroxide, calcium hydroxide, magnesium hydroxide, sodium carbonate, calcium carbonate, or magnesium carbonate, etc.

[0023] The compression device 27 is connected to the scrubber 21 via a pipe 26. The compression device 27 compresses gaseous carbon dioxide. Specifically, the compression device 27 compresses the gas from which the sulfur components have been removed in the scrubber 21 to, for example, 2.5 MPa. The compression device 27 may include a single compressor or may include a plurality of compressors. The compressor may be, for example, a centrifugal compressor. The compression device 27 is connected to the dryer 40 via a pipe 28. The pipe 28 is provided with a heat exchanger 29 and a cooler 30 provided downstream of the heat exchanger 29.

[0024] The heat exchanger 29 exchanges the heat of the carbon dioxide compressed by the compressor 27 with the heat of the carbon dioxide traveling from the cooling device 50 to the reaction device 80. This can reduce the energy required to cool the carbon dioxide sent from the compressor 27 and liquefy it in the cooling device 50. In addition, the energy required to warm the carbon dioxide sent from the cooling device 50 to the reaction device 80 can be reduced. The gas compressed by the compressor 27 is cooled by the heat exchanger 29, and then further cooled to about 50°C by the cooler 30. In this embodiment, an example is described in which carbon dioxide is cooled by the heat exchanger 29 and the cooler 30 to improve the cooling efficiency of carbon dioxide, but the carbon dioxide capture device 20 does not need to be equipped with the heat exchanger 29 and the cooler 30.

[0025] The dryer 40 is disposed between the compressor 27 and the cooling device 50, and dries the gas compressed by the compressor 27 and sends it to the cooling device 50. This removes moisture from the gas, and prevents frost from forming on the cooling device 50 and reduces the cooling efficiency of the cooling device 50. The dryer 40 includes a first drying tank 41 and a second drying tank 43. The first drying tank 41 is filled with a desiccant 42, and the second drying tank 43 is filled with a desiccant 44. The desiccant 42 and the desiccant 44 are provided so that the gas compressed by the compressor 27 comes into contact with them. Therefore, when the gas passes through the first drying tank 41 or the second drying tank 43, the moisture in the gas is absorbed by the desiccant 42 or the desiccant 44, and the moisture is removed from the gas. The desiccant 42 and the desiccant 44 are not particularly limited as long as they can absorb or adsorb moisture, and for example, molecular sieves, silica gel, alumina gel, zeolite, activated carbon, and the like can be used.

[0026] The compression device 27, the first drying tank 41, and the second drying tank 43 are connected via a pipe 28, and a switching valve 45 is provided on the pipe 28. The switching valve 45 can switch the gas flow path so that the gas is supplied from the compression device 27 to the first drying tank 41 or the gas is supplied to the second drying tank 43. The first drying tank 41, the second drying tank 43, and the water supply device 60 are connected via a pipe 52, and a switching valve 46 is provided on the pipe 52. The switching valve 46 can switch the gas flow path so that the gas supplied from the cooling device 50 through the first drying tank 41 is supplied to the water supply device 60, or the gas supplied from the cooling device 50 through the second drying tank 43 is supplied to the water supply device 60. The switching valve 45 and the switching valve 46 are arranged in parallel.

[0027] The first drying tank 41, the second drying tank 43, and the cooling device 50 are connected via a pipe 47, and a switching valve 48 is provided on the pipe 47. The switching valve 48 can switch the gas flow path so as to supply gas from the first drying tank 41 to the cooling device 50, or to supply gas from the second drying tank 43 to the cooling device 50. The first drying tank 41, the second drying tank 43, and the cooling device 50 are connected via a pipe 51, and a switching valve 49 is provided on the pipe 51. The switching valve 49 can switch the gas flow path so as to supply gas supplied from the cooling device 50 to the first drying tank 41, or to supply gas supplied from the cooling device 50 to the second drying tank 43. The switching valve 48 and the switching valve 49 are arranged in parallel.

[0028] The first drying tank 41 and the second drying tank 43 are provided in parallel, and while the gas is being dried with the desiccant in either the first drying tank 41 or the second drying tank 43, the desiccant in the other drying tank can be regenerated. That is, while the gas is being dried with the desiccant 42 in the first drying tank 41, the desiccant 44 in the second drying tank 43 can be regenerated, and while the desiccant 42 in the first drying tank 41 is being regenerated, the gas can be dried with the desiccant 44 in the second drying tank 43. In FIG. 3, the dashed line indicates the flow path of the gas when the gas supplied from the compressor 27 to the cooling device 50 is dried with the desiccant 42 in the first drying tank 41. In FIG. 3, the dashed line indicates the flow path when the moisture of the desiccant 44 in the second drying tank 43 is supplied to the water supply device 60 with the dried gas supplied from the cooling device 50.

[0029] Specifically, the switching valve 45 switches the gas flow path so that the gas supplied from the compression device 27 flows to either the first drying tank 41 or the second drying tank 43. When moisture is removed in the first drying tank 41, the switching valve 48 switches the gas flow path so that the gas from which moisture has been removed in the first drying tank 41 is supplied to the cooling device 50. When moisture is removed in the second drying tank 43, the switching valve 48 switches the gas flow path so that the gas from which moisture has been removed in the second drying tank 43 is supplied to the cooling device 50. In this way, moisture is removed from the gas supplied from the compression device 27 by the dryer 40, and the gas is supplied to the cooling device 50.

[0030] The switching valve 49 switches the gas flow path so that the dry gas supplied from the cooling device 50 flows to either the first drying tank 41 or the second drying tank 43. When the dry gas passes through the first drying tank 41 or the second drying tank 43, moisture is released from the desiccant 42 or the desiccant 44, and the desiccant 42 or the desiccant 44 is regenerated. When the desiccant 42 is regenerated in the first drying tank 41, the switching valve 46 switches the gas flow path so that the gas containing the moisture released from the desiccant 42 is supplied from the first drying tank 41 to the water supply device 60. When the desiccant 44 is regenerated in the second drying tank 43, the switching valve 46 switches the gas flow path so that the gas containing the moisture released from the desiccant 44 is supplied from the second drying tank 43 to the water supply device 60. The gas supplied from the cooling device 50 to the first drying tank 41 or the second drying tank 43 may be heated so that moisture from the desiccant 42 or the desiccant 44 is easily released.

[0031] The cooling device 50 cools the carbon dioxide sent from the compressor 27 to liquefy the carbon dioxide. The cooling device 50 is provided downstream of the dryer 40, and the carbon dioxide is purified and liquefied by cryogenic separation. The gas supplied to the cooling device 50 is cooled to, for example, about -20°C to -50°C to liquefy the carbon dioxide in the gas, and the remaining gas containing impurities that remain as gas without being liquefied is separated. As a result, liquefied carbon dioxide and impurities such as oxygen that have a lower condensation temperature than carbon dioxide are separated from the dry gas dried by the dryer 40. For example, when a gas with a carbon dioxide concentration of 80 to 90%, a temperature of 30°C, and 2.5 MPa is supplied to the cooling device 50, liquefied carbon dioxide with a concentration of about 95 to 99% is collected, and the remaining gas is discharged from the cooling device 50 as a residue of separation and purification. The remaining gas includes, for example, nitrogen, argon, and oxygen.

[0032] The carbon dioxide liquefied in the cooling device 50 preferably contains 95 mol % or more, more preferably 98 mol % or more, and even more preferably 99 mol % or more of carbon dioxide. The carbon dioxide liquefied in the cooling device 50 is supplied to the reaction device 80 via a pipe 53. A part of the carbon dioxide liquefied in the cooling device 50 may be injected into an underground aquifer and stored. In addition, since the gas separated in the cooling device 50 contains almost no moisture, the desiccant 42 and the desiccant 44 in the dryer 40 can be regenerated using the separated gas as described above.

[0033] The gas containing moisture released from the desiccant 42 through the first drying tank 41 from the cooling device 50, and the gas containing moisture released from the desiccant 44 through the second drying tank 43 are cooled in a heat exchanger 54 provided in a pipe 52. The water cooled and condensed in the heat exchanger 54 is stored in a water storage tank 61 of a water supply device 60.

[0034] The water supply device 60 supplies water to the reaction device 80. The water supply device 60 includes a water storage tank 61, a flow rate adjustment unit 62, and a flow rate adjustment unit 63. The water storage tank 61 stores water to be supplied to the reaction device 80. The flow rate adjustment unit 62 is provided on the upstream side of the water storage tank 61 and adjusts the flow rate of water supplied to the water storage tank 61. The flow rate adjustment unit 63 is provided on the downstream side of the water storage tank 61 and adjusts the flow rate of water supplied from the water storage tank 61 to the reaction device 80. The water storage tank 61 is provided with a liquid level gauge 64, and the liquid level gauge 64 measures the amount of water stored in the water storage tank 61. The flow rate adjustment unit 63 may adjust the amount of water supplied to the water storage tank 61 based on the liquid amount of the water storage tank 61 measured by the liquid level gauge 64.

[0035] The raw material supplying device 70 supplies a material containing at least one of an alkali metal and an alkaline earth metal as one of the raw materials to the reactor 80. These elements can react with carbon dioxide and water to produce carbonates. The raw material supplying device 70 includes a hopper 71 and a feeder 72. The hopper 71 stores the above-mentioned material. The feeder 72 adjusts the amount of the above-mentioned material supplied from the hopper 71 to the reactor 80.

[0036] The alkali metal is, for example, at least one element selected from the group consisting of lithium, sodium, and potassium. Examples of substances containing alkali metals include igneous rocks and granite.

[0037] The alkaline earth metal is, for example, at least one of calcium and magnesium. Examples of materials containing alkaline earth metals include waste concrete, steel slag, andesite, basalt, soil, and fly ash. These can be effectively used to fix carbon dioxide while also treating the waste materials.

[0038] The reaction device 80 reacts the carbon dioxide supplied from the cooling device 50 with a substance containing at least one of an alkali metal and an alkaline earth metal, and water to produce carbonate. The substance containing at least one of an alkali metal and an alkaline earth metal is supplied from the raw material supply device 70. Water is supplied from the water supply device 60. The carbonate produced by the reaction device 80 is chemically stable, so that carbon dioxide can be stably stored in a solid state for a long period of time. Therefore, by reacting carbon dioxide to fix it as a carbonate, the properties of the carbonate are maintained stably for a long period of time, so that the carbonate is unlikely to return to carbon dioxide. Even if such carbonate is stored underground, there is a low possibility that carbon dioxide will leak to the ground due to an earthquake or the like, so there is little need to monitor it, and the management costs for carbon dioxide fixation can be reduced.

[0039] The reaction device 80 includes a reaction tank 81, a heating unit 82, and a discharge valve 86. The reaction tank 81 is provided so that carbon dioxide is supplied from the cooling device 50, a substance containing at least one of an alkali metal and an alkaline earth metal is supplied from the raw material supply device 70, and water is supplied from the water supply device 60. In the reaction tank 81, the carbon dioxide, the substance, and water react with each other to produce carbonate.

[0040] The heating unit 82 heats the reaction vessel 81 so that a reaction occurs at a predetermined reaction temperature. The reaction device 80 may be heated by steam generated in the boiler 13, as shown in FIG. 3. The heating unit 82 specifically includes a circulation pipe 83, a flow rate adjustment unit 84, and a thermometer 85. The circulation pipe 83 is provided with the boiler 13, the reaction vessel 81, the flow rate adjustment unit 84, and the thermometer 85. The steam supplied from the boiler 13 heats the reaction vessel 81 and is returned to the boiler 13. The thermometer 85 is disposed between the reaction vessel 81 and the boiler 13, and can measure the temperature of the steam returning from the reaction vessel 81 to the boiler 13. The opening degree of the flow rate adjustment unit 84 may be adjusted based on a signal related to the temperature obtained by the thermometer 85.

[0041] As described above, the reaction in the reactor 80 may be carried out at about room temperature, but from the viewpoint of improving the reaction rate, a higher reaction temperature is preferable. The reactor 80 may be heated by a heater (not shown), but the carbon dioxide fixation system 1 according to this embodiment includes the oxygen combustion power generation device 10 including the oxygen separation section 12 and the boiler 13, as described above. Therefore, by heating the reactor 80 with steam generated in the boiler 13, the energy efficiency of the carbon dioxide fixation system 1 as a whole can be improved.

[0042] In the reaction device 80, carbon dioxide is dissolved in water to produce bicarbonate ions (HCO 3- ) is generated. CO2+H2O→HCO 3- +H + (1)

[0043] Hydrogen carbonate ion (HCO 3- ) reacts to produce carbonate ions (CO3 2- ) is generated. HCO 3- →CO3 2- +H + (2)

[0044] When a substance containing, for example, lithium as an alkali metal is introduced into the reaction vessel 81, a reaction occurs as shown in the following reaction formula (3) to produce lithium carbonate (Li2CO3). 2Li + +CO3 2- →Li2CO3(3)

[0045] When sodium, for example, is added to the reaction vessel 81 as the alkali metal, it reacts as shown in the following reaction formula (4) to produce sodium carbonate (Na2CO3). 2Na + +CO3 2- →Na2CO3(4)

[0046] When potassium, for example, is added to the reaction vessel 81 as the alkali metal, it reacts as shown in the following reaction formula (5) to produce potassium carbonate (K2CO3). 2K + +CO3 2- →K2CO3(5)

[0047] When a substance containing, for example, calcium as an alkaline earth metal is introduced into the reaction tank 81, it reacts as shown in the following reaction formula (6) to produce calcium carbonate (CaCO3). Ca 2+ +CO3 2- →CaCO3(6)

[0048] When a substance containing, for example, magnesium as an alkaline earth metal is introduced into the reaction vessel 81, it reacts as shown in the following reaction formula (7) to produce magnesium carbonate (MgCO3). Mg 2+ +CO3 2-→MgCO3(7)

[0049] The reaction temperature in the reactor 80 is, for example, within a range of 20°C to 300°C. The reaction pressure in the reactor 80 is, for example, within a range of 0.5 MPa to 30 MPa. The reaction time in the reactor 80 is, for example, 12 hours or more. The amount of reaction product tends to increase as the reaction time increases, but if the reaction time exceeds a certain level, the reaction reaches equilibrium, and therefore the upper limit of the reaction time is, for example, 10 days.

[0050] The carbonate generated in the reaction tank 81 is discharged from the reaction tank 81 by opening the discharge valve 86. The discharged carbonate is chemically stable and can be stored for a long period of time at room temperature and pressure. Therefore, by converting at least a portion of the liquid carbon dioxide stored in the underground aquifer into carbonate, carbonate that does not require monitoring is generated, thereby reducing the burden of monitoring.

[0051] As described above, the carbon dioxide fixation system 1 according to this embodiment includes the compression device 27 that compresses gaseous carbon dioxide. The carbon dioxide fixation system 1 includes the cooling device 50 that cools the carbon dioxide sent from the compression device 27 to liquefy the carbon dioxide. The carbon dioxide fixation system 1 includes the reaction device 80 that reacts the carbon dioxide supplied from the cooling device 50 with a substance containing at least one of an alkali metal and an alkaline earth metal, and water to produce carbonate.

[0052] The reaction device 80 can generate carbonates from raw materials including carbon dioxide, a substance containing at least one of an alkali metal and an alkaline earth metal, and water. Carbonates are chemically stable, so there is little need for monitoring, and they can stably fix carbon dioxide. Carbonates can be generated more efficiently at higher pressures, but the compression device 27 requires a large amount of energy to operate. However, in the carbon dioxide fixation system 1 according to this embodiment, the compression device 27 used to liquefy carbon dioxide in the cooling device 50 is also used. Therefore, the carbon dioxide fixation system 1 according to this embodiment can generate carbonates without using a dedicated compression device.

[0053] The carbon dioxide fixation system 1 may further include an oxygen separation unit 12 that separates oxygen from air, and a boiler 13 that burns fuel with the oxygen separated by the oxygen separation unit 12 to generate gaseous carbon dioxide to be supplied to the compression device 27. Since the boiler 13 burns fuel with the oxygen separated by the oxygen separation unit 12, the concentration of carbon dioxide generated by combustion is high. Therefore, high-concentration carbon dioxide can be supplied to the compression device 27, and the carbon dioxide can be easily liquefied by the cooling device 50.

[0054] The reactor 80 may be heated by steam generated in the boiler 13. By heating the reactor 80 by steam generated in the boiler 13, the energy efficiency of the carbon dioxide fixation system 1 as a whole can be improved.

[0055] The carbon dioxide fixation system 1 may further include a heat exchanger 29 that exchanges heat between the carbon dioxide compressed in the compressor 27 and the heat of the carbon dioxide traveling from the cooling device 50 to the reactor 80. The heat exchanger 29 can reduce the energy required to cool the carbon dioxide sent from the compressor 27 and liquefy it in the cooling device 50. In addition, the energy required to warm the carbon dioxide sent from the cooling device 50 to the reactor 80 can be reduced. Therefore, the energy efficiency of the carbon dioxide fixation system 1 as a whole can be improved.

[0056] The alkali metal may be at least one element selected from the group consisting of lithium, sodium, and potassium. These elements are contained in igneous rocks or granite, and can easily form carbonates.

[0057] The alkaline earth metal may be at least one of calcium and magnesium. These elements are contained in waste concrete, steel slag, andesite, basalt, soil, fly ash, etc., and can easily produce carbonates. These elements can also be effectively used to fix carbon dioxide while treating the waste materials.

[0058] Although several embodiments have been described, the embodiments can be modified or modified based on the above disclosure. All components of the above embodiments and all features described in the claims may be individually extracted and combined as long as they are not mutually inconsistent. [Explanation of symbols]

[0059] 1. Carbon dioxide fixation system 12 Oxygen separation section 13. Boiler 27 Compression Device 29 Heat exchanger 50 Cooling device 80 Reactor

Claims

1. A compressor for compressing gaseous carbon dioxide; A cooling device that cools the carbon dioxide sent from the compression device to liquefy the carbon dioxide; a reaction device that reacts the liquefied carbon dioxide supplied from the cooling device, a substance containing at least one of an alkali metal and an alkaline earth metal, and water to produce a carbonate; an oxygen separation unit that separates oxygen from air; a boiler that burns fuel with the oxygen separated by the oxygen separation unit to generate carbon dioxide gas to be supplied to the compression device; Equipped with A carbon dioxide fixation system, wherein the reactor is heated by steam produced in the boiler.

2. A compressor for compressing gaseous carbon dioxide; A cooling device that cools the carbon dioxide sent from the compression device to liquefy the carbon dioxide; a reaction device that reacts the liquefied carbon dioxide supplied from the cooling device, a substance containing at least one of an alkali metal and an alkaline earth metal, and water to produce a carbonate; a heat exchanger for exchanging heat of the carbon dioxide compressed in the compression device with heat of the carbon dioxide flowing from the cooling device to the reaction device; A carbon dioxide fixation system comprising:

3. The carbon dioxide fixation system according to claim 1 or 2, wherein the alkali metal is at least one element selected from the group consisting of lithium, sodium and potassium.

4. The carbon dioxide fixation system according to any one of claims 1 to 3, wherein the alkaline earth metal is at least one element selected from the group consisting of calcium and magnesium.

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