Carbon fixation device and carbon fixation system

Abstract

To provide a carbon fixing device and a carbon fixing system capable of reducing waste by recycling carbon and obtaining calcium carbide with less energy.SOLUTION: The device comprises a second reaction chamber 32 for reacting calcium oxide with carbon by utilizing the reaction heat of a first reaction chamber 30 for reacting carbon dioxide with magnesium.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a carbon fixation device and a carbon fixation system.

Background Art

[0002] Conventionally, in order to reduce carbon dioxide generated by the combustion of fossil fuels in thermal power generation, gas flaring, etc., technologies for carbon fixation are known. Among such technologies, there are those that utilize chemical reactions to capture carbon dioxide and perform carbon fixation.

[0003] The carbon fixation device of Patent Document 1 introduces carbon dioxide and magnesium into a high-temperature reactor and burns them to perform carbon fixation, mainly producing a mixture composed of magnesium oxide and carbon. In order to react carbon dioxide and magnesium, high energy is required as a trigger. The generated magnesium oxide and carbon are not treated as waste but are separated. The magnesium oxide separated by the separation process is recycled to the magnesium used in the above-described carbon fixation reaction by reduction, and the carbon is recycled as a carbon material with increased purity.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in Patent Document 1, carbon is fixed from carbon dioxide in the exhaust gas generated by the combustion of fossil fuels. There are many impurities other than carbon dioxide in the exhaust gas. In particular, in order to recycle carbon as a high-purity carbon material, it is necessary to repeatedly perform cycles of deionized water treatment, hydrochloric acid treatment, ultrasonic treatment, filtration, drying, and heat treatment until the desired purity level is reached, which has the problem of high cost and labor.

[0006] The inventors prefer calcium carbide as a reducing agent used to reduce magnesium from magnesium oxide generated by carbon fixation by burning magnesium and carbon dioxide. Furthermore, it is preferable to use carbon for the production of calcium carbide. In addition, it has been found that the energy required to achieve a high temperature of about 2000 degrees for the production of calcium carbide can be obtained from the reaction heat generated by the combustion reaction of magnesium and carbon dioxide.

[0007] The present invention has been made paying attention to such problems, and an object thereof is to provide a carbon fixation device and a carbon fixation system that can recycle carbon to reduce waste and obtain calcium carbide with less energy.

Means for Solving the Problems

[0008] In order to solve the above problems, the carbon fixation device of the present invention is characterized by including a second reaction chamber that reacts calcium oxide and carbon using the reaction heat of a first reaction chamber that reacts carbon dioxide with magnesium. According to this feature, the carbon generated by the reaction of carbon dioxide and magnesium in the first reaction chamber is reacted with calcium oxide in the second reaction chamber to generate calcium carbide, thereby recycling carbon and reducing waste. At the same time, the reaction heat of the first reaction chamber can be used to obtain the high temperature required for the reaction of calcium oxide and carbon in the second reaction chamber, so that calcium carbide can be obtained with less energy.

[0009] The carbon is characterized in that it is a reaction product in the first reaction chamber heated by the reaction heat. According to this feature, since the carbon, which is a reaction product in the first reaction chamber, is mixed with calcium oxide in the second reaction chamber in a high-temperature state, calcium carbide can be obtained with high energy efficiency without the need for reheating.

[0010] The temperature of the reaction heat is characterized in that it is 2000 degrees to 3000 degrees. According to this feature, the carbon, which is a reaction product in the first reaction chamber, is easily maintained at the temperature required for the reaction with calcium oxide in the second reaction chamber.

[0011] It is characterized by including a third reaction chamber for thermally decomposing calcium carbonate into calcium oxide and carbon dioxide. According to this feature, the carbon dioxide obtained in the third reaction chamber can be used for the reaction in the first reaction chamber, and the calcium oxide obtained in the third reaction chamber can be used for the reaction in the second reaction chamber. Also, since the carbon dioxide obtained in the third reaction chamber is obtained by thermal decomposition of calcium carbonate, it has fewer impurities than the exhaust gas from burning fossil fuels.

[0012] The third reaction chamber is provided downstream of the second reaction chamber and thermally decomposes calcium carbonate into calcium oxide and carbon dioxide using the exhaust heat in the second reaction chamber. According to this feature, since the temperature required for thermal decomposition of calcium carbonate in the third reaction chamber can be obtained using the exhaust heat in the second reaction chamber, energy can be effectively utilized.

[0013] It is characterized by using the carbon dioxide, which is a reaction product in the third reaction chamber, for the reaction in the first reaction chamber. According to this feature, carbon dioxide emissions can be suppressed by the carbon dioxide generation and carbon fixation circulation cycle in the carbon fixation device.

[0014] The carbon fixation system of the present invention An electrolysis device for electrolyzing seawater to obtain calcium carbonate and magnesium hydroxide, a reduction device for reducing the magnesium hydroxide or magnesium oxide with calcium carbide to obtain magnesium and carbon dioxide, a carbon fixation device including a second reaction chamber for reacting calcium oxide with carbon obtained by the reaction in the first reaction chamber by utilizing the reaction heat of the first reaction chamber where carbon dioxide obtained by the reduction device is reacted with magnesium, characterized by having the above. According to this feature, carbon is recycled and waste is reduced by reacting carbon generated by the reaction of carbon dioxide obtained by the reduction device with magnesium in the first reaction chamber with calcium oxide in the second reaction chamber to produce calcium carbide. At the same time, since the high temperature required for the reaction of calcium oxide and carbon in the second reaction chamber can be obtained by utilizing the reaction heat of the first reaction chamber, calcium carbide can be obtained with less energy.

[0015] The carbon fixation device is characterized by including a third reaction chamber for thermally decomposing calcium carbonate obtained by the electrolysis device to obtain calcium oxide to be reacted in the second reaction chamber. According to this feature, calcium carbonate obtained by electrolyzing seawater, which is abundant as a resource, can be thermally decomposed to inexpensively obtain calcium oxide, which is a raw material for calcium carbide. At the same time, by using carbon dioxide generated by the thermal decomposition of calcium carbonate for the reaction in the first reaction chamber, carbon, which is a raw material for calcium carbide, can be obtained. Therefore, carbon dioxide emissions can be suppressed by the circulation cycle of carbon dioxide generation and carbon fixation.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0017] The present invention directly reacts Mg and CO2 by burning them in a state where magnesium (Mg) and carbon dioxide (CO2) are mixed to fix carbon, and uses the temperature of the reaction heat in the reaction to reduce magnesium oxide (MgO) generated by the reaction. It has been found that it is possible to obtain a temperature of about 2000 degrees necessary for the reaction between calcium oxide (CaO) and carbon (C) to produce calcium carbide (CaC2) used as a reducing agent, and based on this, it aims to achieve both carbon fixation and recycling of magnesium and carbon.

[0018] A mode for implementing the carbon fixation device and the carbon fixation system according to the present invention will be described below based on examples.

Example

[0019] As shown in FIG. 1, the carbon fixation system 1 of this example includes an electrolysis device 2 that electrolyzes seawater to obtain calcium carbonate (CaCO3) and magnesium hydroxide (Mg(OH)2), and Mg(OH)2 obtained by the electrolysis device 2 or magnesium oxide (MgO) obtained in the first reaction chamber 30 of the carbon fixation device 10 described later. A reduction device 3 that obtains magnesium (Mg) and carbon dioxide (CO2) by a reduction reaction using calcium carbide (CaC2) as a reducing agent, a first reaction chamber 30 that mainly reacts CO2 generated in the reduction device 3 with Mg obtained in the reduction device 3, and a second reaction chamber 32 that reacts calcium oxide (CaO) with carbon (C) obtained by the reaction in the first reaction chamber 30 using the reaction heat of the first reaction chamber 30, and a third reaction chamber 33 that thermally decomposes CaCO3 obtained by the electrolysis device 2 to obtain CaO that reacts in the second reaction chamber 32, and a carbon fixation device 10.

[0020] Specifically, in the reduction device 3, a reduction reaction of MgO represented by the following reaction formula 1 is performed using CaC2 as a reducing agent, and Mg used in the reaction in the first reaction chamber 30 of the carbon fixation device 10 is generated. MgO + CaC2 → Mg + CaO + 2C ··· (Reaction formula 1)

[0021] The energy required for the reduction reaction of MgO can be provided, for example, by a pulsed power wave. By irradiating the pulsed power wave in an atmosphere of an inert gas and a reducing gas, the reduction efficiency of MgO can be increased. Examples of the inert gas include argon gas, neon gas, helium gas, nitrogen gas, etc. As the reducing gas, carbon monoxide (CO) with low reactivity with CaC2 is preferably used. Oxygen (O2) as a by-product generated by the plasma formation of MgO due to the irradiation of the pulsed power wave reacts with CO to generate CO2. Incidentally, as the CO as the reducing gas, the CO recovered from the reaction in the first reaction chamber 30 (see Reaction formula 3) and the reaction in the second reaction chamber 32 (see Reaction formula 5) of the carbon fixation device 10 described later may be used.

[0022] Also, in the reduction device 3, by heating the Mg(OH)2 obtained in the electrolysis device 2, thermal decomposition represented by the following reaction formula 2 is carried out, and MgO used in the above reduction reaction (see Reaction formula 1) is generated. Mg(OH)2 → MgO + H2O ··· (Reaction formula 2)

[0023] In the first reaction chamber 30 of the carbon fixation device 10, CO2 obtained from the reduction device 3 is reacted with Mg, and carbon fixation represented by the following reaction formula is carried out. Note that the reaction in the first reaction chamber 30 is an exothermic reaction. Specifically, when CO2 is reacted with Mg in a state where the CO2 concentration is relatively higher than that of the atmosphere, CO2 does not completely react with Mg and a part of carbon monoxide (CO) is generated, and the temperature of the reaction heat becomes about 1500 degrees to about 2000 degrees (see Reaction Formula 3). Further, when the CO2 concentration is high, for example, 95% or more, CO2 reacts almost completely with Mg, MgO and C are generated, CO is not generated, and the temperature of the reaction heat becomes about 3000 degrees or more (see Reaction Formula 4). From the viewpoint of the reaction between CO2 and Mg, it is preferable that the CO2 concentration is 100%. In this embodiment, it is preferable that the CO2 concentration is adjusted so that the temperature of the reaction heat in the first reaction chamber 30 becomes about 2000 degrees to about 3000 degrees. Mg + CO2 → MgO + CO ···(Reaction Formula 3) 2Mg + CO2 → 2MgO + C ···(Reaction Formula 4)

[0024] In the second reaction chamber 32, C obtained in the first reaction chamber 30 is reacted with CaO obtained in the third reaction chamber 33, and CaC2 is generated as represented by the following Reaction Formula 5, and recycling of C is carried out. Note that the reaction in the second reaction chamber 32 is an endothermic reaction that requires a temperature of about 2000 degrees. CaO + 3C → CaC2 + CO ···(Reaction Formula 5)

[0025] In the third reaction chamber 33, by applying heat to CaCO3 obtained from the electrolysis device 2, thermal decomposition represented by the following Reaction Formula 6 is carried out, and CaO used in the reaction in the second reaction chamber 32 is generated. Further, CO2 generated together with CaO can be used in the reaction in the first reaction chamber 30. Note that the reaction in the third reaction chamber 33 is an endothermic reaction that requires a temperature of about 800 degrees to 900 degrees. CaCO3 → CaO + CO2 ···(Reaction Formula 6)

[0026] Further, in the electrolysis apparatus 2, since the seawater from which CaCO3 and Mg(OH)2 have been recovered by electrolysis does not contain carbon dioxide gas (bicarbonate ions), carbon may be fixed by absorbing a part of the CO2 generated in the reduction apparatus 3 or the CO2 generated in the third reaction chamber 33 of the carbon fixation apparatus 10 into the seawater.

[0027] Next, the carbon fixation apparatus 10 will be described in detail with reference to FIG. 2. As shown in FIG. 2, the carbon fixation apparatus 10 of the present embodiment can perform carbon fixation and power generation using an introduced gas A1 rich in carbon dioxide (CO2) generated by applying energy required for the reduction reaction in the reduction apparatus 3 by a pulsed power wave.

[0028] The carbon fixation apparatus 10 includes a first reaction chamber 30 that reacts CO2 with magnesium (Mg), a second reaction chamber 32 that reacts carbon (C) obtained in the first reaction chamber 30 with calcium oxide (CaO), a third reaction chamber 33 that thermally decomposes calcium carbonate (CaCO3), a supply means 20 that compresses the introduced gas A1 rich in CO2 and supplies it to the first reaction chamber 30, a second pulsed power wave irradiator 31 that irradiates a pulsed power wave into the first reaction chamber 30, a power generation means 40 that generates power using the energy of the gas A4 supplied from the first reaction chamber 30, a separator 60 disposed on the downstream side of the power generation means 40 and capable of separating CO2 and carbon monoxide (CO), a circulation means 80 that supplies the gas A9 containing CO2 from which CO has been separated by the separator 60 to the supply means 20, and an exhaust means 90 that discharges the residual gas A10 whose energy has been used for power generation by the power generation means 40. In the following description, the reduction apparatus 3 side will be described as the upstream side, and the downstream side will be described as the side of the eighth communication path 91 described later of the exhaust means 90.

[0029] First, the supply means 20 will be described. The supply means 20 mainly consists of, in order from the upstream side, a first connection passage 21 connected to the downstream side of the reduction device 3, a first pulse power wave irradiator 22 that irradiates a pulse power wave into the first connection passage 21, a cooler 23 disposed on the downstream side of the first connection passage 21, a second connection passage 24 disposed on the downstream side of the cooler 23, an axial compressor 25 connected to the downstream side of the second connection passage 24, and a third connection passage 26 connected to the downstream side of the compressor 25 and the upstream side of the first reaction chamber 30.

[0030] The first connection passage 21 is connected not only to the reduction device 3 but also to a check valve 82 of the circulation means 80 described later, and the gas A9 can flow into the first connection passage 21 from the check valve 82.

[0031] The first pulse power wave irradiator 22 is capable of performing a first pulse streamer discharge from a plug 22a disposed inside the first connection passage 21 and upstream of the confluence point with the check valve 82 described later. In this embodiment, the first pulse power wave irradiator 22 can generate a high voltage with a half-value width of 80 ns by means of a repetitive operation, with a charging voltage of 20 kV, a discharge current of 170 A, and the power supply operated at 5 pps (Pulses Per Second), thereby irradiating the first pulse power wave and causing the first pulse streamer discharge. Thus, it is essential to operate with short pulses, high voltage and small current, and short cycles so as not to cause glow discharge or arc discharge. In this embodiment, since the introduced gas A1 that is rich in CO2 and has few impurities generated by being applied by the pulse power wave is used, the first pulse power wave irradiator 22 may not be provided. Also, depending on the temperature of the introduced gas A1, the cooler 23 may not be provided either.

[0032] The first reaction chamber 30 is formed to have high heat resistance and high pressure resistance, and Mg powder can be introduced through an inlet (not shown). Note that the Mg to be introduced may have a shape other than powder, such as flake or bar. Also, a plug 31a of the second pulse power wave irradiator 31 is disposed inside the first reaction chamber 30, enabling the execution of second pulse streamer discharge inside the first reaction chamber 30. Further, a turbine 42 of the gas turbine power generation device 41 is disposed on the downstream side inside the first reaction chamber 30. In this embodiment, the second pulse power wave irradiator 31 can generate a high voltage with a half-value width of 40 ns by repetitive operation, with a charging voltage of 100 kV, a discharge current of 170 A, and the power supply operated at 10 pps, thereby irradiating the second pulse power wave and causing the second pulse streamer discharge. Thus, it is essential to operate with short pulses, high voltage and small current, and short cycles to prevent glow discharge and arc discharge.

[0033] The power generation means 40 includes a gas turbine power generation device 41 that can generate electricity using the high-temperature and high-pressure gas A4 generated by the reaction of CO2 and Mg inside the first reaction chamber 30. The gas turbine power generation device 41 mainly consists of a turbine 42 rotated by the pressure of the high-temperature and high-pressure gas A4 and a power generation device 43 capable of generating electricity in response to the rotation of the turbine 42.

[0034] The second reaction chamber 32 is disposed on the downstream side of the turbine 42 of the gas turbine power generation device 41, and the gas A5 whose temperature and pressure have decreased after passing through the turbine 42 passes through it. Also, CaO powder obtained in the third reaction chamber 33 can be introduced through an inlet (not shown). Note that the CaO to be introduced may have a shape other than powder, such as flake or bar. Also, the CaO powder is not limited to that obtained in the third reaction chamber 33 and may be, for example, CaO obtained by the reduction reaction of MgO using CaC2 as a reducing agent in the reduction device 3.

[0035] The third reaction chamber 33 is disposed on the downstream side of the second reaction chamber 32. The gas A6, whose temperature and pressure have further decreased after passing through the second reaction chamber 32, passes through it, and it is possible to introduce the CaCO3 powder obtained by the electrolysis device 2 (see FIG. 1) from an inlet (not shown).

[0036] The separator 60 is disposed on the downstream side of the fourth communication path 50 connected to the downstream side of the third reaction chamber 33. Also, on the downstream side of the separator 60, a fifth communication path 70 into which the gas A8 from which CO has been recovered from the gas A7 flows, and a seventh communication path 71 into which the gas A11 with a high CO concentration due to the recovered CO flows are respectively connected. Further, a storage tank 72 for CO is connected to the downstream side of the seventh communication path 71.

[0037] The circulation means 80 is mainly composed of the above-described fifth communication path 70, a three-way valve V connected to the downstream side of the fifth communication path 70, a sixth communication path 81 connected to one downstream side of the three-way valve V, and a check valve 82 connected to the downstream side of the sixth communication path 81.

[0038] The discharge means 90 is mainly composed of the above-described fifth communication path 70, the three-way valve V, and an eighth communication path 91 connected to the other downstream side of the three-way valve V and communicating with the outside of the carbon fixation device 10. In FIG. 2, the valve to which the eighth communication path 91 of the three-way valve V is connected is in a closed state.

[0039] Next, the operation will be described. The CO2-rich introduced gas A1 obtained by the reduction device 3 flows into the first communication path 21. The introduced gas A1 has a CO2 concentration of about 70% or more, and in addition to CO2, it contains nitrogen (N2), hydrogen (H2), oxygen (O2), water vapor (H2O), etc. Also, the temperature of the introduced gas A1 is about 300 degrees, and the flow rate per unit time is 0.1×10 -4 m 3 / s.

[0040] As indicated by the arrow, the introduced gas A1 introduced into the first connection passage 21 is generated by the non-thermal equilibrium plasma continuously irradiated from the plug 22a of the first pulse power wave irradiator 22 by the first pulse streamer discharge. The reactions of H2, O2, H2O, etc. contained in the introduced gas A1 are promoted, and the impurities are further reduced.

[0041] As indicated by the arrow, the introduced gas A1 is led to the cooler 23 and cooled to become a gas A2 of about 30 degrees. The gas A2 passes through the second connection passage 24 as indicated by the arrow and is then compressed by the compressor 25.

[0042] As indicated by the arrow, the compressed and pressurized gas A3 with a pressure of about 2.0 MPa and a flow rate of 5.0×10 -5 m 3 / s flows through the third connection passage 26 and into the first reaction chamber 30 into which Mg powder is introduced. In the first reaction chamber 30, a second pulse streamer discharge for a short time is performed from the plug 31a of the second pulse power wave irradiator 31, and non-thermal equilibrium plasma is generated in the first reaction chamber 30. It was confirmed that CO2 and Mg contained in the gas A3 directly react with each other by this non-thermal equilibrium plasma to generate magnesium oxide (MgO), carbon (C), carbon monoxide (CO), etc. That is, carbon fixation of CO2 is carried out, and the CO2 concentration of the gas A3 is reduced.

[0043] By this reaction, reaction heat is generated, and the temperature in the first reaction chamber 30 becomes about 2000 degrees to about 3000 degrees. Even after the second pulse power wave irradiation is stopped, it is observed that CO2 and Mg continuously react by the inflow of the gas A3 into the first reaction chamber 30.

[0044] In this way, in a state where Mg and CO2 have not yet reacted, it is possible to react Mg and CO2 using the second pulse streamer discharge as a trigger, and for the reaction after the reaction between Mg and CO2 starts, it is possible to continuously react by the generated high-temperature reaction heat.

[0045] In addition, due to the reaction between CO2 and Mg, as the temperature of gas A3 rises rapidly, gas A3 expands rapidly, resulting in a high-temperature and high-pressure gas A4, which is ejected to the downstream side.

[0046] As shown by the arrow, gas A4 attempts to flow from the downstream side of the first reaction chamber 30 into the second reaction chamber 32. At this time, gas A4 rotates the turbine 42 of the gas turbine power generation device 41 disposed between the first reaction chamber 30 and the second reaction chamber 32. As the turbine 42 is rotated with the passage of gas A4, power generation is performed by the power generation device 43 of the gas turbine power generation device 41.

[0047] The high-temperature gas A5 at about 2000 degrees to about 3000 degrees that has flowed into the second reaction chamber 32 contains particles of a mixture mainly composed of MgO and C generated by the reaction in the first reaction chamber 30. It was confirmed that C in gas A5 reacts with the CaO powder introduced into the second reaction chamber 32 to generate calcium carbide (CaC2), carbon monoxide (CO), etc.

[0048] In addition, due to the endothermic reaction between MgO and C, as the temperature of gas A5 drops rapidly, gas A5 contracts rapidly, resulting in a gas A6 with a reduced temperature and pressure, which is ejected to the downstream side.

[0049] It was confirmed that the high-temperature gas A6 at about 1100 degrees that has flowed into the third reaction chamber 33 reacts with the CaCO3 powder introduced into the third reaction chamber 33 to generate calcium oxide (CaO), carbon dioxide (CO2), etc.

[0050] In addition, due to the thermal decomposition reaction of CaCO3, which is an endothermic reaction, as the temperature of gas A6 drops rapidly, gas A6 contracts rapidly, resulting in a gas A7 with an even lower temperature and pressure, which is ejected to the downstream side.

[0051] The gas A7 flowing out from the third reaction chamber 33 is led to the separator 60 through the fourth connecting passage 50 as indicated by the arrow. In the separator 60, since CO contained in the gas A7 is separated, it is separated into a gas A11 containing high-concentration CO and a gas A8 which is the remaining gas from which CO has been separated. The gas A11 containing high-concentration CO is enclosed in the storage tank 72 through the seventh connecting passage 71 as indicated by the arrow.

[0052] On the other hand, the gas A8 which is the remaining gas from which CO has been separated is led to the fifth connecting passage 70 as indicated by the arrow. A concentration sensor (not shown) capable of measuring the CO2 concentration contained in the gas A8 is provided in the fifth connecting passage 70. In the case of the gas A9 where the CO2 concentration is constant (10 vol% or more in this embodiment), the eighth connecting passage 91 side of the three-way valve V is in the closed valve state, and the fifth connecting passage 70 and the sixth connecting passage 81 side are in the open valve state. Thereby, the gas A9 is led to the first connecting passage 21 through the three-way valve V, the sixth connecting passage 81, and the check valve 82 as indicated by the arrow, and the above-described cycle is repeatedly performed together with the introduced gas A1. That is, a part of the CO2 generated by the thermal decomposition reaction of CaCO3 in the third reaction chamber 33 is carbon-fixed by the reaction with Mg in the first reaction chamber 30.

[0053] Also, in the case of the remaining gas A10 where the CO2 concentration is less than a certain value (10 vol% in this embodiment), the sixth connecting passage 81 side of the three-way valve V is in the closed valve state, and the fifth connecting passage 70 and the eighth connecting passage 91 side are in the open valve state. Thereby, the remaining gas A10 is discharged to the outside through the three-way valve V and the eighth connecting passage 91 as indicated by the dotted arrow.

[0054] As described above, in the carbon fixation device 10 of the present embodiment, by irradiating the pressurized carbon dioxide (CO2)-rich introduced gas A3 with a pulse power wave from the second pulse power wave irradiator 31 to cause a second pulse streamer discharge, CO2 can be reacted with magnesium (Mg). As a result, at least magnesium oxide (MgO) and carbon (C) are generated to fix carbon, and since this reaction reaches a high temperature of about 2000 degrees to about 3000 degrees, a high-temperature and high-pressure gas A4 is generated, so the power generation efficiency by the power generation means 40 is high.

[0055] In addition, by reacting carbon (C) generated by the reaction of Mg and CO2 in the first reaction chamber 30 of the carbon fixation device 10 with calcium oxide (CaO) in the second reaction chamber 32 to generate calcium carbide (CaC2), the C generated by the reaction in the first reaction chamber 30 is recycled to reduce waste, and the high temperature (about 2000 degrees) required for the reaction of CaO and C in the second reaction chamber 32 can be obtained by utilizing the reaction heat of the first reaction chamber 30. Therefore, CaC2 can be obtained with less energy. Specifically, by reacting C in a high-temperature state (about 2000 degrees to about 3000 degrees), which is a reaction product in the first reaction chamber 30, with CaO introduced into the second reaction chamber 32, CaC2 can be obtained with high energy efficiency without the need to reheat the second reaction chamber 32.

[0056] In addition, since the temperature of the reaction heat by the reaction of Mg and CO2 in the first reaction chamber 30 is about 2000 degrees to about 3000 degrees, C, which is a reaction product in the first reaction chamber 30, is easily maintained at the temperature required for the reaction with CaO in the second reaction chamber 32.

[0057] In addition, the carbon fixation device 10 includes a third reaction chamber 33 that thermally decomposes calcium carbonate (CaCO3) into CaO and CO2. As a result, the CO2 obtained in the third reaction chamber 33 can be carbon-fixed by reacting with Mg in the first reaction chamber 30, and the CaO obtained in the third reaction chamber 33 can be used as a material for producing CaC2 in the second reaction chamber 32. Further, since the CO2 obtained in the third reaction chamber 33 has fewer impurities than the exhaust gas generated by burning fossil fuels, the reaction efficiency between Mg and CO2 can be improved.

[0058] In addition, the third reaction chamber 33 is disposed downstream of the second reaction chamber 32, and the waste heat in the second reaction chamber 32 can be used to obtain the temperature required for the thermal decomposition of CaCO3 in the third reaction chamber 33, so that energy can be effectively utilized.

[0059] In addition, since the CO2, which is a reaction product in the third reaction chamber 33, can be carbon-fixed by reacting with Mg in the first reaction chamber 30, the discharge of CO2 can be suppressed by the circulation cycle of CO2 generation and carbon fixation in the carbon fixation device 10.

[0060] In addition, the carbon fixation system 1 of this embodiment includes an electrolysis device 2 that electrolyzes seawater to obtain CaCO3 and magnesium hydroxide (Mg(OH)2), a reduction device 3 that reduces Mg(OH)2 obtained by the electrolysis device 2 or MgO obtained in the first reaction chamber 30 of the carbon fixation device 10 with CaC2 to obtain Mg and CO2, a second reaction chamber 32 that reacts CO2 generated by the reduction device 3 with C obtained by reacting CaO with the reaction in the first reaction chamber 30 using the reaction heat of the first reaction chamber 30, and a third reaction chamber 33 that thermally decomposes CaCO3 obtained by the electrolysis device 2 to obtain CaO for reaction in the second reaction chamber 32. Since it has a carbon fixation device 10, CaCO3 obtained by electrolyzing seawater, which is abundant as a resource, can be thermally decomposed to inexpensively obtain CaO, which is a raw material for CaC2. By using CO2 generated by the thermal decomposition of CaCO3 for the reaction with Mg in the first reaction chamber 30, C, which is a raw material for CaC2, can be obtained. Therefore, CO2 emissions can be suppressed by the circulation cycle of CO2 generation and carbon fixation. In addition, not only CaO, which is a raw material for CaC2, but also Mg and Ca required for the reactions in each reaction chamber of the reduction device 3 and the carbon fixation device 10 that make up the carbon fixation system 1 can be obtained inexpensively.

[0061] As described above, the embodiments of the present invention have been described with reference to the drawings. However, the specific configuration is not limited to these embodiments, and modifications and additions within the scope not departing from the gist of the present invention are also included in the present invention.

[0062] For example, in the above embodiment, the carbon fixation device 10 has been described as being applied to the reduction device 3. However, it is not limited to this. As long as it is a facility that generates a gas with a predetermined CO2 concentration, it can also be applied to other facilities such as thermal power plants. Further, a gas in which CO2 obtained by the reduction device 3 and exhaust gas containing CO2 obtained by burning a fossil fuel (not shown) are mixed may be introduced into the carbon fixation device 10.

[0063] Also, although the pulsed streamer discharge by the first pulse power wave irradiator 22 has been described as being performed in the first communication path 21, it is not limited to this, and it may be performed in the second communication path 24 after cooling by the cooler 23, or it may be performed in the third communication path 26 after compression by the compressor 25, and it is not limited as long as it is within the range until it is introduced into the first reaction chamber 30.

[0064] Also, although the compressor 25 has been described as being separately arranged from the gas turbine power generation device 41, it is not limited to this, and it may be configured to compress the gas by using the rotational force of the turbine 42 of the gas turbine power generation device 41 rotated by the gas A4.

[0065] Also, although the trigger for reacting Mg and CO2 has been described as being configured to irradiate a short-time second pulse streamer discharge, it is not limited to this, and a temperature sensor may be arranged in the first reaction chamber 30, and when the temperature measured by the temperature sensor becomes 2000 degrees or less, the second pulse streamer discharge may be irradiated each time. Further, it may be configured to continuously irradiate the second pulse streamer discharge during the period in which Mg and CO2 are continuously reacted.

[0066] In the above embodiment, introduced gas A1 with a CO2 concentration of about 70% or more was introduced into the first reaction chamber 30, and reaction heat of 2,000 to 3,000 degrees was obtained by reacting with Mg. By utilizing this, the temperature required for the reactions in the second reaction chamber 32 and the third reaction chamber 33 disposed downstream of the first reaction chamber 30 was described. However, the present invention is not limited to this. For example, by setting the CO2 concentration of the introduced gas A1 to about 55% or more, the reaction heat in the first reaction chamber 30 may be in the range of about 1,500 degrees to about 2,000 degrees. According to this, by making the reaction heat in the first reaction chamber 30 relatively lower than that in the above embodiment, the range of selection of the structures constituting the first reaction chamber 30 of the carbon fixation device 10 and the power generation means 40 becomes wider, and these structures can be simplified. Further, in this case, in order to obtain the temperature required for the reactions in the second reaction chamber 32 and the third reaction chamber 33 disposed downstream of the first reaction chamber 30, for example, the temperature in each reaction chamber may be increased by pulse streamer discharge.

[0067] Also, an example in which the reaction heat of 2,000 to 3,000 degrees by the reaction of CO2 and Mg is used for the reaction of C and CaO in the second reaction chamber 32 was described. However, it is also possible to use this reaction heat for other reactions. For example, those that obtain hydrogen and acetylene or hydrogen and carbon, particularly carbon black, from hydrocarbons such as methane by utilizing this reaction heat can be mentioned.

[0068] Also, the embodiment in which the third reaction chamber 33 is disposed downstream of the second reaction chamber 32 was described. However, the present invention is not limited to this. The third reaction chamber may be disposed upstream of the second reaction chamber so that the CaO obtained in the third reaction chamber can be directly used for the reaction of generating CaC2 in the second reaction chamber.

[0069] Further, as shown in the modification example of FIG. 3, the turbine 142 of the gas turbine power generation device 141 and the second reaction chamber 132 are arranged in parallel on the downstream side of the first reaction chamber 30, and a third reaction chamber 133 is arranged on the downstream side of the turbine 142. The gas flow may be configured to merge in the fourth communication passage 150 on the downstream sides of the second reaction chamber 132 and the third reaction chamber 133. Further, the turbine, the second reaction chamber, and the third reaction chamber may be arranged in parallel on the downstream side of the first reaction chamber.

[0070] Further, the turbine of the gas turbine power generation device is not limited to the configuration arranged on the downstream side of the first reaction chamber, and may be selectively arranged on the downstream side of the second reaction chamber or the third reaction chamber according to conditions such as the temperature and pressure of the gas.

[0071] Further, CaO or C obtained by the reduction reaction in the reduction device 3 may be used for the reaction of generating CaC2 in the second reaction chamber 32. Thus, the raw materials used in various reactions in the carbon fixation system 1 are preferably obtained from other reactions within the carbon fixation system 1, but raw materials obtained from outside the carbon fixation system 1 may also be used.

[0072] Further, if the temperature of the gas A7 derived from the third reaction chamber 33 is sufficiently high, for example, a cooler for cooling the high-temperature gas A7 is arranged on the downstream side of the third reaction chamber 33, and power generation may be performed by a steam turbine power generation device that rotates the turbine with the steam generated during the cooling of the gas A7 by the cooler. In this case, the water or steam flowing through the cooler 23 heated by the heat of the introduced gas A1 may also be used for power generation by the steam turbine power generation device.

[0073] Further, the thermal decomposition reaction of CaCO3 in the third reaction chamber may be performed using the reaction heat in the first reaction chamber or the exhaust heat in the second reaction chamber, and the third reaction chamber does not have to form a continuous flow path with the first reaction chamber or the second reaction chamber. In this case, the third reaction chamber and the first reaction chamber may be connected by a communication passage (not shown) so that the CO2 obtained in the third reaction chamber can be directly used for the reaction in the first reaction chamber.

[0074] In addition, the CO2 used in the reaction in the first reaction chamber is not limited to the CO2 obtained by the reduction device 3 or the CO2 obtained by the third reaction chamber, and may be CO2 obtained by other means.

Explanation of symbols

[0075] 1 Carbon fixation system 2 Electrolysis device 3 Reduction device 10 Carbon fixation device 30 First reaction chamber 32 Second reaction chamber 33 Third reaction chamber

Claims

1. It is provided with a second reaction chamber for reacting calcium oxide with carbon, which is a reaction product in the first reaction chamber heated by the reaction heat and the reaction heat of the first reaction chamber where carbon dioxide reacts with magnesium, It further includes a third reaction chamber for thermally decomposing calcium carbonate into calcium oxide and carbon dioxide by using the waste heat in the second reaction chamber, A carbon fixation device, characterized in that carbon dioxide, which is a reaction product in the third reaction chamber, is used for the reaction in the first reaction chamber.

2. The carbon fixation device according to Claim 1, characterized in that the temperature of the reaction heat is 2000 degrees to 3000 degrees.

3. The carbon fixation device according to Claim 1 or 2, characterized in that the third reaction chamber is provided downstream of the second reaction chamber.

4. An electrolysis device for electrolyzing seawater to obtain calcium carbonate and magnesium hydroxide, a reduction device for reducing the magnesium hydroxide or magnesium oxide with calcium carbide to obtain magnesium, and a carbon fixation device including a second reaction chamber for reacting calcium oxide with carbon obtained by the reaction in the first reaction chamber by using the reaction heat of the first reaction chamber where carbon dioxide reacts with the magnesium obtained by the reduction device.

5. The carbon fixation system according to Claim 4, characterized in that the carbon fixation device includes a third reaction chamber for thermally decomposing the calcium carbonate obtained by the electrolysis device to obtain calcium oxide for reaction in the second reaction chamber.

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