Double fixing device

Abstract

To provide a new and efficient carbon fixation apparatus.SOLUTION: A carbon fixation apparatus includes: a reaction chamber 30 for reacting carbon dioxide with magnesium; reaction initiation means 31 for starting the reaction; charging means 36 for charging magnesium hydride; supply means 20 for introducing pressurized carbon dioxide-rich gas A3 into the reaction chamber 30; and discharge means 90 for discharging gases generated in response to the reaction.SELECTED DRAWING: Figure 1

Description

Technical Field

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

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] Patent Document 1 describes a carbon fixation device including a combustion furnace that burns fuels containing ash such as coal, garbage, etc., and a reaction chamber that carbonates calcium oxide in the combustion ash with carbon dioxide in the combustion exhaust gas discharged from the combustion furnace. In the reaction chamber, an introduced gas containing carbon dioxide and calcium oxide are mixed, and the temperature in the reaction chamber is adjusted to 750 degrees. As a result, carbonation due to the reaction between carbon dioxide and calcium oxide is promoted in the reaction chamber, and carbon fixation is performed. Further, the reaction heat generated along with this reaction is recovered and the recovered heat is used for power generation.

[0004] In a carbon fixation device such as that of Patent Document 1, by supplying combustion exhaust gas at a high temperature of 700 degrees generated by the combustion of coal, garbage, etc. into the reaction chamber, calcium oxide is carbonated with heat generation, so that the temperature in the reaction chamber can be maintained at 750 degrees without using energy for separate heating.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in carbon fixation devices for power generation such as those described in Patent Document 1, it is necessary to maintain the temperature in the reaction chamber below 780 degrees Celsius in order to fix carbon by carbonation through the reaction of carbon dioxide with calcium oxide, making it difficult to increase power generation efficiency.

[0007] In response to this, the inventors have been researching a method of burning magnesium and carbon dioxide to improve power generation efficiency and fix carbon using the high heat generated during combustion. However, because magnesium is highly reactive, some of it would react with other substances before reacting with carbon dioxide, reducing the efficiency of carbon fixation. After further research to address this issue, the researchers found a way to react magnesium with carbon dioxide before it reacts with other substances.

[0008] This invention was made in view of these problems, and aims to provide a new, highly efficient carbon fixation device. [Means for solving the problem]

[0009] To solve the above problems, the carbon fixation apparatus of the present invention is The apparatus is characterized by comprising: a reaction chamber for reacting carbon dioxide with magnesium; a reaction initiation means for starting the reaction; an input means for introducing magnesium hydride; a supply means for supplying a pressurized carbon dioxide-rich introduction gas to the reaction chamber; and an exhaust means for discharging the gas produced in response to the reaction. According to these characteristics, since the carbon fixation device uses magnesium hydride, it is less likely to react with other substances compared to when pure magnesium is used. Furthermore, because magnesium readily reacts with carbon dioxide in the introduced gas supplied from the supply means, the efficiency of carbon fixation can be increased.

[0010] The aforementioned input means is characterized by inputting magnesium separated from magnesium hydride by the separation means into the reaction chamber. According to this characteristic, since magnesium is obtained by separating it from magnesium hydride, the separated magnesium readily reacts with carbon dioxide in the introduced gas supplied from the supply means.

[0011] The separation means is characterized by thermally separating magnesium hydride from magnesium in a separation chamber using the reaction heat of the reaction chamber. According to this characteristic, the thermally separated magnesium is at a high temperature, making it readily react with carbon dioxide, and hydrogen can be efficiently recovered in the separation chamber.

[0012] The separation means is characterized by directly supplying magnesium hydride to the reaction chamber and using the reaction heat of the reaction chamber to thermally separate magnesium from the magnesium hydride. This characteristic allows for thermal separation of magnesium by directly supplying magnesium hydride to the reaction chamber. In addition, the thermally separated magnesium is at a high temperature and therefore readily reacts with carbon dioxide.

[0013] The aforementioned reaction heat is characterized by a temperature of 2000 to 3000 degrees Celsius. According to this characteristic, because the reaction chamber is at a high temperature, an explosive reaction between the hydrogen thermally separated from magnesium hydride and the small amount of oxygen contained in the carbon dioxide-rich air is unlikely to occur.

[0014] It is characterized by having an oxygen sensor that measures oxygen concentration in carbon dioxide-rich air. This feature allows for the supply of carbon dioxide-rich air to the reaction chamber at a predetermined oxygen concentration that prevents explosive reactions from occurring. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic diagram showing a carbon fixation apparatus in Example 1 of the present invention. [Figure 2] This is a schematic diagram showing a carbon fixation apparatus in Example 2 of the present invention.

Mode for Carrying Out the Invention

[0016] The present invention has found that by utilizing magnesium hydride (MgH₂) which is difficult to react with other substances, magnesium (Mg) separated before reacting with other substances can be reacted with carbon dioxide (CO₂), and based on this, a completely new carbon fixation is attempted.

[0017] A mode for carrying out the carbon fixation device according to the present invention will be described below based on examples.

Example

[0018] The carbon fixation device 10 of this example is for carrying out carbon fixation by reacting carbon dioxide (CO₂) with magnesium (Mg). As shown in FIG. 1, the carbon fixation device 10 of this example can perform carbon fixation and power generation using the carbon dioxide-rich introduced gas A1 generated by burning fossil fuel in the combustion furnace 1 of a thermal power plant.

[0019] The carbon fixation device 10 includes a supply means 20, a reaction chamber 30, a reaction start means 31, a separation means 36, a power generation means 40, a separator 60, a circulation means 80, and a discharge means 90. In the following description, the side of the combustion furnace 1 will be described as the upstream side, and the side of the eighth connection passage 91 described later of the discharge means 90 will be described as the downstream side.

[0020] First, the supply means 20 will be described. The supply means 20 is configured to compress the CO₂-rich introduced gas A1 and supply it to the reaction chamber 30.

[0021] The supply means 20 mainly consists of, in order from the upstream side, a first connecting passage 21 connected to the downstream side of the combustion furnace 1, a pulsed power wave irradiator 22 that irradiates pulsed power waves into the first connecting passage 21, a cooler 23 disposed downstream of the first connecting passage 21, a second connecting passage 24 disposed downstream of the cooler 23, an axial flow type compressor 25 connected to the downstream side of the second connecting passage 24, and a third connecting passage 26 connected downstream of the compressor 25 and upstream of the reaction chamber 30.

[0022] A circulation means 80 is also connected to the first connecting passage 21, allowing gas A7 to be introduced through the check valve 82.

[0023] The pulsed power wave irradiator 22 is capable of performing pulsed streamer discharge from a plug 22a located in the first communication passage 21 and upstream of the point where it merges with the check valve 82, which will be described later. In this embodiment, the pulsed power wave irradiator 22 is capable of repeatedly generating a high voltage with a half-width of 80 ns, and by setting the charging voltage to 20 kV, the discharge current to 170 A, and operating the power supply at 5 pps (Pulses Per Second), pulsed power waves are irradiated and pulsed streamer discharge is generated. Thus, it is important to operate with short pulses, high voltage, low current, and short cycles to prevent glow discharge and arc discharge. Note that if the amount of impurities that hinder the reaction between CO2 and Mg, such as NOx and SOx, is small in the introduced gas A1, the pulsed power wave irradiator 22 may not be installed. Also, depending on the temperature of the introduced gas A1, the cooler 23 may not be installed.

[0024] The second communication passage 24 is provided with an O2 sensor 27 that is cooled by a cooler 23 and measures the O2 concentration in the gas A2 passing through the second communication passage 24.

[0025] Furthermore, the second connecting passage 24 is provided with a carbon dioxide supply means 28 for adjusting the O2 concentration of gas A2 by supplying CO2 to it. However, the carbon dioxide supply means 28 is not required to be provided.

[0026] In reaction chamber 30, CO2 is reacted with Mg to fix carbon as shown by reaction equations 1 and 2 below. The reaction in reaction chamber 30 is an exothermic reaction. Specifically, when CO2 is reacted with Mg at a CO2 concentration relatively higher than that of the atmosphere, the CO2 does not react completely with Mg, producing some CO, and the reaction temperature is approximately 1500°C to 2000°C (see reaction equation 1). Furthermore, when the CO2 concentration is high, for example 95% or more, the CO2 reacts almost completely with Mg, producing MgO and C, and no CO is produced, resulting in a reaction temperature of approximately 3000°C or higher (see reaction equation 2). From the viewpoint of the reaction between CO2 and Mg, a CO2 concentration of 100% is preferable. In this embodiment, it is preferable to adjust the CO2 concentration so that the reaction temperature in reaction chamber 30 is approximately 2000°C to 3000°C. Mg + CO2 → MgO + CO2 ... (Reaction Equation 1) 2Mg + CO2 → 2MgO + C··· (Reaction Equation 2)

[0027] Assuming the above reaction, the reaction chamber 30 is constructed to be highly heat-resistant and high-pressure resistant. Inside the reaction chamber 30 are an ignition plug 31a for electrically generating a spark, an acetylene supply port 31b for supplying acetylene (C2H2), an oxygen supply port 31c for supplying O2, and a magnesium supply port 36a for introducing Mg powder. The Mg introduced may be in a form other than powder, such as flakes, pellets, bars, or cylinders. Furthermore, a porous structure with pores and a large specific surface area is preferable as it reacts easily with CO2.

[0028] The reaction initiation means 31 is configured to combust C2H2 with O2 in the reaction chamber 30 to promote the reaction between CO2 and Mg before the reaction starts. The reaction initiation means 31 includes a spark plug 31a, an acetylene supply port 31b, an oxygen supply port 31c, an acetylene generation chamber 34, an acetylene flow path 31d connecting the acetylene generation chamber 34 and the acetylene supply port 31b, an oxygen cylinder 35, an oxygen flow path 31e connecting the oxygen cylinder 35 and the oxygen supply port 31c, and a flow control valve 31f provided in the middle of the oxygen flow path 31e.

[0029] Furthermore, the spark plug may be of a type that generates a red-hot glow rather than one that electrically generates a spark. Also, the number and arrangement of the acetylene supply ports 31b and oxygen supply ports 31c may be changed as appropriate, for example, by arranging multiple acetylene supply ports 31b equally around one oxygen supply port 31c, as long as it is possible to efficiently mix C2H2 and O2.

[0030] The acetylene generation chamber 34 is located outside the reaction chamber 30 and is configured to supply calcium carbide (CaC2) and water (H2O). When these are mixed, C2H2 can be generated (see reaction equation 3). This allows for the supply of an appropriate amount of C2H2 without the need to store C2H2 itself for a long period of time, and is safe because only CaC2 needs to be stored. CaC2 + 2H2O → C2H2 + Ca(OH)2 ... (Reaction Equation 3)

[0031] The separation means 36 mainly consists of a magnesium supply port 36a, a separation chamber 36b in which MgH2 pellets are separated into Mg and hydrogen (H2), a magnesium hydride tank 36c in which MgH2 pellets are stored, a hydrogen tank 36d in which H2 generated in the separation chamber 36b is recovered, and a magnesium flow path 36e connecting the magnesium supply port 36a to the separation chamber 36b. In this embodiment, by pelletizing MgH2, unintended explosive reactions are less likely to occur compared to, for example, nanoparticle-shaped MgH2, thus allowing for safe and easy storage. However, if the storage system is appropriate, MgH2 may be stored in a state other than pellets, such as fine particles. Furthermore, the separation means 36 can also be considered the input means for the carbon fixation device 10 in this invention.

[0032] As indicated by the dotted arrow, heat generated by the combustion reaction of Mg and CO2 in the reaction chamber 30 is supplied to the separation chamber 36b. As a result, when MgH2 pellets are introduced from the magnesium hydride tank 36c into the separation chamber 36b, MgH2 is thermally separated (see reaction equation 4). Meanwhile, the H2 produced in this reaction is recovered in the hydrogen tank 36d. Since the hydrogen tank 36d is located above the reaction chamber 30 and the separation chamber 36b, H2 is less likely to flow into the reaction chamber 30 and can be easily recovered in the hydrogen tank 36d. MgH2 → Mg + H2 ... (Reaction Equation 4)

[0033] The turbine 42 of the gas turbine power generation device 41 is located on the downstream side of the reaction chamber 30.

[0034] The power generation means 40 includes a gas turbine power generation device 41 capable of generating electricity using high-temperature, high-pressure gas A4 generated by the reaction of CO2 and Mg in the reaction chamber 30. The gas turbine power generation device 41 mainly consists of a turbine 42 that is rotated by the pressure of the high-temperature, high-pressure gas A4, and a power generation device 43 that is capable of generating electricity in accordance with the rotation of the turbine 42.

[0035] The separator 60 is located downstream of the fourth communication passage 50, which is connected to the downstream side of the turbine 42, and is intended to separate the CO contained in gas A5. Further downstream of the separator 60 are the fifth communication passage 70, into which the remaining gas A6 after the CO has been recovered from gas A5 flows, and the seventh communication passage 71, into which gas A9 containing the CO recovered from gas A5 flows. Further downstream of the seventh communication passage 71 is a carbon monoxide tank 72 for storing CO.

[0036] The circulation means 80 is configured to supply gas A7, which is determined to have a high CO2 concentration, to the supply means 20. The circulation means 80 mainly consists of the fifth communication passage 70 described above, a three-way valve V connected to the downstream side of the fifth communication passage 70, a sixth communication passage 81 connected to one of the downstream sides of the three-way valve V, and a check valve 82 connected to the downstream side of the sixth communication passage 81.

[0037] The discharge means 90 is configured to discharge gas A8, which has been determined to have a low CO2 concentration. It mainly consists of the aforementioned fifth communication passage 70, a three-way valve V, and an eighth communication passage 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 Figure 2, the valve to which the eighth communication passage 91 of the three-way valve V is connected is in a closed state.

[0038] Next, the operation will be explained. The CO2-rich introduced gas A1 obtained from the combustion furnace 1 flows into the first communication passage 21. The introduced gas A1 has a CO2 concentration of about 70%, and also contains nitrogen (N2), hydrogen (H2), oxygen (O2), water vapor (H2O), etc. The temperature of the introduced gas A1 is about 300 degrees, and the flow rate per unit time is 0.1 × 10⁻⁶. -4 m 3 It is / s.

[0039] As indicated by the arrows, the introduced gas A1 into the first passage 21 is subjected to a non-thermal equilibrium plasma generated by a pulsed streamer discharge continuously irradiated from the plug 22a of the pulsed power wave irradiator 22. This promotes the reaction of H2, O2, H2O, etc. contained in the introduced gas A1, further reducing the amount of impurities.

[0040] As indicated by the arrow, the introduced gas A1 is led to the cooler 23 where it is cooled to a temperature of approximately 30 degrees Celsius, becoming gas A2. If the O2 concentration in gas A2, as measured by the O2 sensor 27, is below a predetermined O2 concentration that does not cause an explosive reaction with H2, then gas A2 passes through the second communication passage 24, as indicated by the arrow, and is compressed by the compressor 25. On the other hand, if the O2 concentration in gas A2 exceeds a predetermined O2 concentration, the carbon dioxide supply means 28 adjusts the O2 concentration of gas A2 to be below the predetermined O2 concentration, and then it is compressed by the compressor 25. The predetermined O2 concentration is updated according to the temperature change inside the reaction chamber 30.

[0041] In this embodiment, the streamer discharge by the pulsed power wave irradiator 22 activates hydrogen, reducing the amount of H2 contained in the introduced gas A1. Furthermore, the H2 generated during MgH2 separation is recovered in the hydrogen tank 36d, resulting in a very low H2 concentration in the reaction chamber 30. Therefore, the predetermined O2 concentration in this embodiment can also be set to a relatively high value. If it is possible to reduce the O2 concentration in gases A1 and A2, substances other than CO2 may be additionally supplied to gases A1 and A2. Alternatively, the O2 in gases A1 and A2 may be reduced by reacting it with other substances using a well-known method, separate from the pulsed streamer discharge.

[0042] As indicated by the arrow, the pressure is approximately 2.0 MPa, and the flow rate per unit time is 5.0 × 10⁻⁶. -5 m 3 The compressed and pressurized gas A3 at 1 / s passes through the third connecting passage 26 and flows into the reaction chamber 30 into which the Mg powder is being introduced.

[0043] In the reaction chamber 30, the reaction initiation means 31 triggers the reaction between CO2 and Mg using the heat generated by burning C2H2 with O2 (approximately 2000°C to 3500°C). This confirmed that CO2 and Mg in gas A3 reacted directly, producing MgO, C, CO, etc. In other words, carbon fixation of CO2 occurred, and the CO2 concentration in gas A3 was reduced.

[0044] Furthermore, the Mg powder is pumped together with CO2 gas from the magnesium supply port 36a towards the combustion flame of C2H2 and O2. This is to prevent the Mg from reacting with other substances. In other words, CO2 gas is used as an inert gas. Alternatively, gas A3 pumped from the compressor 25 may be used as the CO2 gas. In addition, any inert gas may be changed as appropriate. Furthermore, when separating MgH2 in the form of pellets or cylindrical bulk materials larger than the powder (for example, with a characteristic length of several mm or more) in the separation chamber 36b, it is also preferable to introduce the Mg bulk material from which hydrogen has been separated into the reaction chamber 30 with CO2 gas blown onto it.

[0045] In this way, since the mixed gas of C2H2 and O2 can be burned with the Mg powder mixed in, the Mg powder can be heated efficiently. Furthermore, the Mg powder supplied to the reaction chamber 30 is at a high temperature, having just been thermally separated from MgH2 in the separation chamber 36b. This also makes the Mg powder more readily reactive with CO2.

[0046] After the combustion of Mg by CO2 began and reaction heat was generated, gas A3 flowed into the reaction chamber 30, and Mg powder was supplied from the magnesium supply port 36a, causing the CO2 and Mg to react continuously. At this time, the temperature inside the reaction chamber 30 was approximately 2000°C to 3000°C.

[0047] Furthermore, if the combustion of Mg by CO2 does not start due to the reaction heat generated by burning C2H2 with O2, the combustion of C2H2 with O2 is repeated at predetermined intervals until the combustion of Mg by CO2 starts. After the combustion of Mg by CO2 starts, the opening of the flow control valve 31f is reduced or the valve is closed, so the combustion of the mixed gas is stopped.

[0048] Thus, while Mg and CO2 have not yet undergone a combustion reaction, the combustion of C2H2 and O2 by the reaction initiation means 31 can be used as a trigger to initiate the reaction between Mg and CO2. After the reaction between Mg and CO2 has started, the reaction can be continuously carried out by the high-temperature reaction heat generated.

[0049] The reaction between CO2 and Mg causes a rapid increase in the temperature of gas A3, leading to its rapid expansion. This results in high-temperature, high-pressure gas A4, which is then ejected downstream.

[0050] As indicated by the arrow, gas A4 attempts to flow into the fourth communication passage 50 from the downstream side of the reaction chamber 30. At this time, gas A4 rotates the turbine 42 of the gas turbine power generation device 41, which is located between the reaction chamber 30 and the fourth communication passage 50. As the turbine 42 rotates due to the passage of gas A4, electricity is generated by the power generation device 43 of the gas turbine power generation device 41.

[0051] As indicated by the arrow, gas A5 that has passed through turbine 42 is led to separator 60 via fourth communication passage 50. In separator 60, the CO contained in gas A5 is separated, resulting in gas A9 containing a high concentration of CO and gas A6, which is the remaining gas from which the CO has been separated. Gas A9 containing a high concentration of CO is sealed into carbon monoxide tank 72 via seventh communication passage 71, as indicated by the arrow.

[0052] Meanwhile, gas A6, the remaining gas from which CO has been separated, is led to the fifth communication passage 70, as indicated by the arrow. The fifth communication passage 70 is equipped with a CO2 sensor (not shown) capable of measuring the CO2 concentration contained in gas A6. When the CO2 concentration of gas A7 is above a certain level (10 vol%), the eighth communication passage 91 side of the three-way valve V becomes closed, and the fifth communication passage 70 and the sixth communication passage 81 side become open. As a result, gas A7 is led to the first communication passage 21 through the three-way valve V, the sixth communication passage 81, and the check valve 82, as indicated by the arrow, and the cycle described above is repeated together with the introduced gas A1.

[0053] Furthermore, in the case of gas A8 with a CO2 concentration below a certain level (10 vol%), the sixth communication passage 81 side of the three-way valve V becomes closed, and the fifth communication passage 70 and the eighth communication passage 91 side become open. As a result, gas A8 is discharged to the outside through the three-way valve V and the eighth communication passage 91, as indicated by the dotted arrows.

[0054] As described above, in the carbon fixation apparatus 10 of this embodiment, the reaction heat generated by the combustion of acetylene (C2H2) and oxygen (O2) by the reaction initiation means 31 is supplied to the pressurized carbon dioxide (CO2)-rich introduced gas A3, thereby allowing CO2 to react with magnesium (Mg). As a result, carbon fixation is achieved by generating at least magnesium oxide (MgO) and carbon (C), and since this reaction reaches a high temperature of approximately 2000 to 3000 degrees Celsius, a high-temperature, high-pressure gas A4 is generated, resulting in high power generation efficiency by the power generation means 40.

[0055] Furthermore, since the carbon fixation device 10 uses magnesium hydride (MgH2), it is less likely to react with other substances compared to the case where pure magnesium (Mg) is used. Also, because Mg is obtained by separating it from MgH2, the separated Mg readily reacts with CO2 in gas A3 supplied from the supply means 20 before it can react with other substances, thereby increasing the efficiency of carbon fixation. For example, in a device that supplies highly reactive pure Mg to the reaction chamber 30, there is a risk of combustion reaction with O2 in the gas before it is introduced into the reaction chamber 30. In other words, safety can be increased by directly supplying MgH2 into the separation means 36.

[0056] Furthermore, the MgO generated in reaction chamber 30 can be recovered and reduced to Mg by plasma generation using a plasma separation device (not shown). The Mg reduced from MgO can then be hydrogenated and supplied to separation chamber 36b for recycling. Alternatively, when using a non-equilibrium plasma device, the surface portion of the MgO can be reduced to Mg, and this reduced surface portion can be hydrogenated and supplied to separation chamber 36b. The MgO before reduction may be in particulate or pellet form, but in any state, it is preferable that it has a porous structure from the viewpoint of efficiency in reduction and hydrogenation. While a plasma separation device using non-equilibrium plasma has been given as an example of a separation device, it is not limited to this; any separation device capable of reducing MgO to Mg, such as one utilizing high heat or microwaves, may be used, and may be modified as appropriate.

[0057] Furthermore, although the separation chamber 36b has been described as being located outside the reaction chamber 30, it is not limited to this configuration; a separation chamber may also be provided independently within the reaction chamber 30, in the wall of the reaction chamber 30. Such a configuration not only simplifies the means of supplying the heat generated in the reaction chamber 30 to the separation chamber, but also reliably reduces the reaction of the separated Mg with other substances. [Examples]

[0058] The carbon fixation apparatus according to Example 2 will be described with reference to Figure 3. Note that descriptions that are identical to those of the previous example and therefore redundant will be omitted. The carbon fixation apparatus 110 of this example includes a pulsed power wave irradiator 131 (reaction initiation means) for initiating the reaction by irradiating pulsed power waves into the reaction chamber 130, a magnesium hydride supply means 136 for supplying magnesium hydride (MgH2) pellets into the reaction chamber 130, and a hydrogen tank 136d for recovering hydrogen (H2) from the fourth communication passage 50.

[0059] The pulsed power wave irradiator 131 for initiating the reaction is capable of repeatedly generating a high voltage with a half-width of 40 ns. By setting the charging voltage to 100 kV, the discharge current to 170 A, and operating the power supply at 10 pps, the pulsed power wave for initiating the reaction is irradiated, generating a pulsed streamer discharge for initiating the reaction. Thus, it is crucial to operate with short pulses, high voltage, low current, and short cycles to prevent glow discharge or arc discharge.

[0060] The magnesium hydride supply means 136 mainly consists of a magnesium hydride supply port 136a, a magnesium hydride tank 36c, and a magnesium hydride flow path 136e that connects the magnesium hydride supply port 136a to the magnesium hydride tank 36c.

[0061] Furthermore, the MgH2 added may be in a form other than pellets, such as powder, flakes, bars, or tubes. It is also preferable that the MgH2 has a porous structure with pores and a large specific surface area, as this facilitates its reaction with CO2.

[0062] This confirmed that, within the reaction chamber 130, the non-thermal equilibrium plasma generated by a short pulse streamer discharge from the plug 131a of the pulse power wave irradiator 131 for initiating the reaction directly reacted with the Mg for initiating the reaction and the CO2 contained in gas A3, producing MgO, C, CO, etc. In other words, carbon fixation of CO2 occurred, and the CO2 concentration in gas A3 was reduced.

[0063] Furthermore, the Mg used at the start of the reaction between CO2 and Mg may be separated from MgH2 as in Example 1, or it may be the Mg remaining after the previous carbon fixation, and may be changed as appropriate.

[0064] When the reaction between Mg and CO2 begins, the magnesium hydride supply means 136 supplies MgH2 into the reaction chamber 130 from the magnesium hydride supply port 136a. The high-temperature reaction heat generated by the reaction between CO2 and Mg causes thermal separation of Mg and H2, and this Mg can continue to react with the CO2 contained in gas A3. In other words, the reaction chamber 130 also functions as a separation means. Furthermore, because the thermally separated Mg is at a high temperature, it readily reacts with CO2. In addition, by adjusting the timing and temperature of supplying MgH2 into the reaction chamber 130, MgH2 can be reliably separated within the reaction chamber 130. In contrast, in a device that supplies highly reactive pure Mg into the reaction chamber 130, there is a risk of combustion with gaseous O2 before it enters the reaction chamber 130. In other words, safety can be enhanced by directly supplying MgH2 into the reaction chamber 130.

[0065] Although we have described an example in which Mg and H2 are thermally separated by the high-temperature reaction heat generated by the reaction of CO2 and Mg, it is also possible to adjust the reaction heat, pressure, etc., so that the MgH2 supplied into the reaction chamber 130 from the magnesium hydride supply port 136a reacts directly with CO2.

[0066] Furthermore, in this embodiment as well, the temperature inside the reaction chamber 130 is approximately 2000°C to 3000°C, similar to the first embodiment. Here, water (H2O) separates into hydrogen molecules (H2) and oxygen molecules (O2) when its temperature exceeds 2000°C, and separates into hydrogen atoms (H) and oxygen atoms (O) when its temperature exceeds 2500°C. Therefore, even if hydrogen is generated inside the reaction chamber 130 due to the thermal separation of MgH2, an explosive reaction with the small amount of oxygen contained in gas A3 is unlikely to occur.

[0067] In addition, the O2 that flows into reaction chamber 130 reacts with Mg. This also makes explosive reactions less likely.

[0068] Furthermore, similar to Example 1, even when the temperature inside the reaction chamber 130 is below 2000 degrees, the oxygen concentration of gas A3 is adjusted by the O2 sensor 27 and the carbon dioxide supply means 28, making explosive reactions less likely to occur.

[0069] Furthermore, since H2 is recovered in the hydrogen tank 136d located in the fourth connecting passage 50, an explosive reaction between H2 and O2 outside the reaction chamber 130 is prevented. The method of recovering H2 in the hydrogen tank 136d is a well-known method.

[0070] Although embodiments of the present invention have been described above with reference to the drawings, the specific configurations are not limited to these embodiments, and any changes or additions that do not depart from the spirit of the present invention are also included.

[0071] For example, in the above embodiment, the carbon fixation device 10 was described as having a power generation means 40, but it is not limited to this configuration. It does not have to have a power generation means 40, it may be used as a boiler, or it may be used solely for carbon fixation, and may be modified as appropriate.

[0072] Furthermore, although the above embodiment was described as a configuration in which MgH2 is thermally separated, the method is not limited to this. For example, MgH2 may be reacted with water (H2O) to form MgO, and then reduced to Mg using the plasma separation apparatus described above. The method for obtaining Mg may be changed as appropriate. [Explanation of Symbols]

[0073] 10 Carbon fixation device 20 Means of supply 27 O2 sensor 30 Reaction Chamber 31 Reaction Initiation Means 36 Separation means (input means) 36b Separation room 90 Means of discharge 110 Carbon Fixing Device 130 Reaction chamber (separation means) 131. Pulsed power wave irradiator (reaction initiation means) 136 Magnesium hydride supply means A1 Introduced gas A3 Pressurized carbon dioxide-rich introductory gas

Claims

1. A carbon fixation apparatus comprising: a reaction chamber for reacting carbon dioxide with magnesium; a reaction initiation means for initiating the reaction; an input means for introducing magnesium hydride; a supply means for supplying a pressurized carbon dioxide-rich introduction gas to the reaction chamber; and a discharge means for discharging the gas produced in response to the reaction.

2. The carbon fixation apparatus according to claim 1, characterized in that the input means inputs magnesium separated from magnesium hydride by the separation means into the reaction chamber.

3. The carbon fixation apparatus according to claim 2, characterized in that the separation means uses the reaction heat of the reaction chamber to thermally separate magnesium hydride into magnesium in the separation chamber.

4. The carbon fixation apparatus according to claim 2, characterized in that the separation means uses the reaction heat of the reaction chamber to thermally separate magnesium from magnesium hydride by directly supplying magnesium hydride to the reaction chamber.

5. The carbon fixation apparatus according to claim 4, characterized in that the reaction heat is at a temperature of 2000 to 3000 degrees.

6. A carbon fixation apparatus according to any one of claims 1 to 5, characterized by having an oxygen sensor for measuring the oxygen concentration in carbon dioxide-rich air.

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