Carbon dioxide fixing device

Abstract

To provide a carbon dioxide fixing device excellent in amount of carbon dioxide to be fixed and efficiency.SOLUTION: A carbon dioxide fixing device 10 comprises: a reaction tank 11; an inlet 12 which is provided in the upper part of the reaction tank 11 and through which a cement hardening body is input into the reaction tank 11; a gas inlet 13 which is provided at the lower part of the reaction tank 11 and through which a carbon dioxide-containing gas can be input into the reaction tank 11; and a gas outlet 15 through which the carbon dioxide-containing gas generated by reacting the cement hardening body with the carbon dioxide can be discharged out of the reaction tank 11.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Carbon Capture and Utilization (CCU), which fixes carbon dioxide contained in the exhaust gas from industrial furnaces, is known as a technology for reducing emissions of carbon dioxide (CO2), a greenhouse gas, into the atmosphere.

[0003] One such technology that has been developed is one that efficiently fixes carbon dioxide by bringing a cementitious hardened material such as cement or concrete into contact with a carbon dioxide-containing gas to carbonate it. Waste materials such as waste concrete and concrete sludge can be used as the cementitious hardened material, allowing for effective utilization of resources. In this case, a rotary kiln may be used as a carbon dioxide fixation device. In recent years, there has been a demand for increasing the amount of carbon dioxide fixation. For example, the technology described in Patent Document 1 uses water vapor to improve fixation efficiency. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-146817 Summary of the Invention

[0005] However, there is a demand for further increasing the amount of carbon dioxide fixation. While increasing the size of the rotary kiln increases the amount of carbon dioxide fixation, it requires a large installation area, making it difficult to secure an installation location. Furthermore, the temperature and moisture content of the cementitious hardened body housed in the rotary kiln may become uneven, reducing the efficiency of carbon dioxide fixation. [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a carbon dioxide fixation device that fixes carbon dioxide in an excellent amount and with an excellent efficiency. [Means for solving the problem]

[0007] The carbon dioxide fixation device of the present invention is characterized by comprising: a reaction tank; an inlet provided in an upper part of the reaction tank and capable of introducing a cementitious hardened body into the reaction tank; a gas supply port provided in a lower part of the reaction tank and capable of supplying a carbon dioxide-containing gas into the reaction tank; and a gas outlet capable of discharging the carbon dioxide-containing gas obtained by reacting the cementitious hardened body with carbon dioxide outside the reaction tank.

[0008] According to the carbon dioxide fixation apparatus of the present invention, the cementitious hardened body introduced from above falls within the reaction tank, while the carbon dioxide-containing gas supplied from below rises within the reaction tank. This allows the cementitious hardened body and the carbon dioxide-containing gas to come into countercurrent contact, making this contact uniform and highly efficient. Furthermore, since the carbon dioxide-containing gas penetrates into the gaps in the cementitious hardened body accumulated at the bottom of the reaction tank, this contact can be maintained for a long period of time. As a result, the proportion (amount) of carbon dioxide fixed in the cementitious hardened body increases, making it possible to efficiently fix carbon dioxide.

[0009] Furthermore, since the apparatus is a vertical type apparatus in which the supply port and gas discharge port are provided at the top of the reaction tank and the gas supply port is provided at the bottom of the reaction tank, when treating a large amount of carbon dioxide-containing gas, it is sufficient to extend the apparatus vertically, and it is possible to install the apparatus in a compact site area.

[0010] The carbon dioxide fixation apparatus of the present invention preferably further comprises an outlet provided in a lower part of the reaction tank and capable of discharging the carbonated hardened cementitious material to the outside of the reaction tank.

[0011] In this case, the carbonated hardened cementitious material can be easily discharged.

[0012] The carbon dioxide fixation apparatus of the present invention preferably includes a water vapor supply port capable of supplying water vapor into the reaction vessel.

[0013] In this case, it becomes easy to create a humidity environment inside the reaction tank suitable for increasing the proportion (amount) of immobilized carbon dioxide.

[0014] In the carbon dioxide fixation apparatus of the present invention, it is preferable to further include a retaining means that is provided in a lower part of the reaction tank and is capable of retaining at least a part of the introduced cementitious hardened body within the reaction tank.

[0015] In this case, the carbon dioxide-containing gas also comes into contact with the cementitious hardened body held in the holding means, making it possible to fix the carbon dioxide more efficiently.

[0016] In the carbon dioxide fixation apparatus of the present invention, it is preferable that the reaction vessel is provided with a baffle plate inclined downward.

[0017] In this case, the presence of the baffle plate increases the time it takes for the cementitious hardened body to fall within the reaction tank, thereby increasing the time for countercurrent contact between the cementitious hardened body and the carbon dioxide-containing gas, thereby enabling more efficient fixation of carbon dioxide.

[0018] The carbon dioxide fixation apparatus of the present invention preferably includes a stirring means capable of stirring the cementitious hardened body introduced into the reaction tank and the carbon dioxide-containing gas supplied into the reaction tank.

[0019] In this case, stirring by the stirring means makes the atmosphere in the reaction tank uniform, and also changes the area of ​​the cementitious hardened body that comes into contact with the carbon dioxide-containing gas, making it possible to fix carbon dioxide more efficiently.

[0020] The carbon dioxide fixation apparatus of the present invention preferably includes a fan capable of forming a swirling flow of the carbon dioxide-containing gas supplied into the reaction tank.

[0021] In this case, the carbon dioxide-containing gas is supplied into the reaction tank as a swirling flow, whereby the cementitious hardened body is blown away and the area in contact with the carbon dioxide-containing gas changes, making it possible to fix carbon dioxide more efficiently.

[0022] In the carbon dioxide fixation apparatus of the present invention, the reaction tank is preferably configured as a pressure-resistant vessel.

[0023] In this case, by increasing the amount of carbon dioxide-containing gas supplied to the reaction tank, the pressure inside the reaction tank can be increased, and more of the carbon dioxide-containing gas penetrates into the gaps in the cementitious hardened body inside the reaction tank, thereby ensuring more reliable contact and enabling more efficient fixation of carbon dioxide.

[0024] The carbon dioxide fixation apparatus of the present invention preferably includes a vibration means capable of vibrating the reaction tank.

[0025] In this case, by vibrating the reaction tank, the cementitious hardened body contained therein is also vibrated, so that the part of the cementitious hardened body that comes into contact with the carbon dioxide-containing gas changes, making it possible to fix carbon dioxide more efficiently. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a schematic diagram of a carbon dioxide fixation system including a carbon dioxide fixation device according to an embodiment of the present invention. [Figure 2] FIG. 1 is a schematic diagram of a carbon dioxide fixation system including a carbon dioxide fixation device according to a first modified example of an embodiment of the present invention. [Figure 3]FIG. 10 is a schematic diagram of a carbon dioxide fixation system including a carbon dioxide fixation device according to a second modified example of the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] A carbon dioxide fixation system 100 including a carbon dioxide fixation device 10 according to an embodiment of the present invention will be described with reference to Fig. 1. In the carbon dioxide fixation system 100, carbon dioxide (CO2) in a carbon dioxide-containing gas reacts with a cementitious hardened body to be carbonated and fixed as calcium carbonate (CaCO3).

[0028] The term "cementitious hardened product" refers to a product formed by hardening a composition containing cement and water, such as a hardened product made of concrete, a hardened product made of mortar, a hardened product made of cement paste, etc. In this specification, the term "cementitious hardened product" includes not only a completely hardened product but also a semi-hardened product (in other words, a product in the process of hardening).

[0029] From the viewpoint of promoting the utilization of waste, the hardened cement product to be recycled is preferably used as the hardened cement product. Examples of the hardened cement product to be recycled include recycled aggregate, waste building materials made of concrete (waste concrete) or mortar, waste hardened cement paste, and sludge (completely hardened or semi-hardened sludge after dehydration treatment) generated in ready-mixed concrete.

[0030] The powdery granular material made of a cementitious hardened material has a particle size of 100 mm or less, preferably 80 mm or less, and more preferably 50 mm or less, in order to increase the contact area with the carbon dioxide-containing gas and thereby increase the amount of immobilized carbon dioxide. Here, the particle size refers to the maximum dimension of the powdery granular material (for example, the dimension of the major axis when the cross section is elliptical).

[0031] Furthermore, the carbon dioxide-containing gas may be exhaust gas from a cement factory or a coal-fired power plant, or may be highly purified gas separated and recovered from factory exhaust gas.

[0032] The proportion of carbon dioxide gas in the carbon dioxide-containing gas, as a volume fraction, is preferably 5% or more, more preferably 10% or more, even more preferably 15% or more, and particularly preferably 20% or more. When the proportion is 5% or more, the amount of carbon dioxide fixed increases, which is preferable because it increases the effect of reducing carbon dioxide emissions into the atmosphere.

[0033] The carbon dioxide fixation device 10 includes a reaction tank 11, an inlet 12 provided at the top of the reaction tank 11 and capable of introducing a cementitious hardened body into the reaction tank 11, a gas supply port 13 provided at the bottom of the reaction tank 11 and capable of supplying a carbon dioxide-containing gas into the reaction tank 11, an outlet 14 provided at the bottom of the reaction tank 11 and capable of discharging the carbonated cementitious hardened body out of the reaction tank 11, and a gas outlet 15 capable of discharging the carbon dioxide-containing gas obtained by reacting the cementitious hardened body with carbon dioxide out of the reaction tank 11.

[0034] The reaction vessel 11 is a sealed or semi-sealed vessel made of stainless steel or the like. Here, the reaction vessel 11 is formed in a cylindrical shape with a tapered bottom. Although not shown, a heater may be disposed around the reaction vessel 11 so that the area within the reaction vessel 11 surrounded by the heater is heated. This makes it easier to control the temperature environment within the reaction vessel 11.

[0035] The inlet 12 is provided in the upper part of the reaction tank 11, in this case, on the top surface of the reaction tank 11. However, the inlet 12 may also be provided in the upper part of the side surface of the reaction tank 11. The cementitious hardened body supplied from the cementitious hardened body supply device 20 is introduced into the reaction tank 11 through the inlet 12.

[0036] The cementitious hardened body supplying device 20 here comprises a hopper 21 that stores the cementitious hardened body, and a constant volume feeder 22 composed of a circle feeder, a table feeder, a screw feeder or the like that is capable of constant volume supply of the cementitious hardened body supplied from the hopper 21. As a result, a desired amount of cementitious hardened body is supplied into the reaction tank 11 through the supply port 12.

[0037] Gas supply port 13 is provided at the bottom of reaction tank 11, here on the inclined surface at the bottom of reaction tank 11. However, gas supply port 13 may also be provided at the bottom of the side of reaction tank 11, etc. Also, here, gas supply port 13 is provided at only one location, but it may be provided at multiple locations. Carbon dioxide-containing gas supplied from gas supply device 30 is supplied into reaction tank 11 via gas supply port 13.

[0038] Here, the gas supply device 30 is composed of a gas storage tank 31 for storing carbon dioxide-containing gas, a flow rate controller 32 arranged downstream of the gas storage tank 31, and a gas supply pipe 33 for supplying the carbon dioxide-containing gas supplied from the gas storage tank 31 via the flow rate controller 32 into the reaction tank 11 from the gas supply port 13.

[0039] The discharge outlet 14 is provided at the bottom of the reaction tank 11, in this case, at the lower end of the reaction tank 11. The discharge outlet 14 is composed of an opening / closing means capable of ensuring the airtightness of the reaction tank 11, such as a rotary valve, a double flap damper, or a non-sliding valve. By opening the discharge outlet 14, the cementitious hardened body contained in the reaction tank 11 can be discharged to the outside.

[0040] Gas outlet 15 is provided at the top of reaction tank 11, in this case at the top of the side surface of reaction tank 11. However, gas outlet 15 may also be provided on the top surface of reaction tank 11. Through gas outlet 15, the carbon dioxide-containing gas in reaction tank 11 is released to the outside of carbon dioxide fixation device 10 via gas treatment device 40.

[0041] Here, gas treatment device 40 is composed of a discharge pipe 41 provided at gas outlet 15, a pump 42 provided downstream of discharge pipe 41, and a dust collector 43 such as a bag filter provided in discharge pipe 41 upstream of pump 42. As a result, fine powder contained in the carbon dioxide-containing gas and the cementitious hardened body is collected by dust collector 43, and clean gas is discharged to the outside. This gas may be supplied again into reaction tank 11 via gas supply port 13.

[0042] Here, the carbon dioxide fixation apparatus 10 further includes a water vapor supply port 16 provided at the bottom of the reaction tank 11, capable of supplying water vapor into the reaction tank 11. The water vapor supply port 16 is provided at the bottom of the reaction tank 11, in this case, on the inclined surface of the bottom of the reaction tank 11. However, the water vapor supply port 16 may also be provided at the bottom, middle, top, side, etc. of the reaction tank 11. Here, the water vapor supply port 16 is provided in only one location at the bottom, but it may also be provided in multiple locations at any part, such as the bottom, middle, top, or side, or any combination of these parts. It is particularly preferable to provide multiple water vapor supply ports 16 at the bottom or top, or to provide multiple water vapor supply ports 16 at the bottom. Water vapor supplied from the water vapor supply device 50 is supplied into the reaction tank 11 via the water vapor supply port 16. The water vapor in the reaction tank 11 is discharged through the gas outlet 15.

[0043] The water vapor supply device 50 is composed of a boiler 51 that heats water to generate water vapor, a steam heater 52 that heats the water vapor generated by the boiler 51, a flow rate controller 53 provided downstream of the steam heater 52, and a water vapor supply pipe 54 that supplies the heated water vapor from the water vapor supply port 16 into the reaction tank 11. Note that the carbon dioxide fixation device 10 may be provided with a water supply port that can supply water into the reaction tank 11 instead of or in addition to the water vapor supply port 16.

[0044] Here, carbon dioxide fixation apparatus 10 further includes holding means 17, which is provided in the lower part of reaction tank 11 and holds at least a portion of the introduced hardened cementitious body in reaction tank 11. Holding means 17 is made of canvas, wire mesh, perforated stainless steel plate, or the like, which is capable of holding a cementitious hardened body of a certain size or larger on its upper surface. Holding means 17 prevents all of the cementitious hardened body introduced into reaction tank 11 from being piled up in the lower part of reaction tank 11.

[0045] A method for immobilizing carbon dioxide using the above-described carbon dioxide immobilization system 100 will be described below.

[0046] First, a carbon dioxide-containing gas is supplied from the gas supply device 30 into the reaction vessel 11 via the gas supply port 13. Furthermore, preferably, water vapor is supplied from the water vapor supply device 50 into the reaction vessel 11 via the water vapor supply port 16. As a result, the internal temperature of the reaction vessel 11 is preferably set to 60 to 150°C, and the internal humidity is preferably set to 30 to 95% RH. By setting the temperature and humidity within these ranges, the proportion (amount) of carbon dioxide that is immobilized increases.

[0047] Next, the cementitious hardened material is introduced into the reaction tank 11 from the cementitious hardened material supply device 20 through the introduction port 12. The introduced cementitious hardened material falls downward within the reaction tank 11.

[0048] At this time, the carbon dioxide-containing gas supplied from the lower part of the reaction tank 11 rises from the lower part to the upper part inside the reaction tank 11. As a result, the cementitious hardened body and the carbon dioxide-containing gas come into countercurrent contact with each other, and the contact is uniform and highly efficient. Furthermore, until the discharge port 14 is opened and the cementitious hardened body is discharged to the outside, the carbon dioxide-containing gas exists in the gaps between the cementitious hardened body accumulated at the lower part of the reaction tank 11. In addition, the carbon dioxide-containing gas also comes into contact with the cementitious hardened body held in the holding means 17. As a result, the contact between the cementitious hardened body and the carbon dioxide-containing gas can be maintained for a long period of time.

[0049] Therefore, the proportion (amount) of carbon dioxide fixed in the hardened cementitious material increases, and as a result, carbon dioxide can be fixed more efficiently.

[0050] Furthermore, carbon dioxide fixation apparatus 10 is an apparatus in which inlet 12 and gas outlet 15 are provided in the upper part of reaction tank 11, and gas supply port 13 is provided in the lower part of reaction tank 11. Because it is such a vertical apparatus, when treating a large amount of carbon dioxide-containing gas, it is sufficient to extend it vertically, and therefore it can be installed in a compact site area.

[0051] The carbon dioxide fixation apparatus 10 does not necessarily have to be equipped with the exhaust port 14. In this case, the carbon dioxide fixation apparatus 10 may be used in a batchwise manner, and the cementitious hardened body that has been subjected to the reaction may be directly recovered from the reaction tank 11.

[0052] A modified example of the carbon dioxide fixation device 10 described above will now be described.

[0053] 2, the carbon dioxide fixation apparatus of the first modification has baffle plates 61 inclined downward inside the reaction vessel 11. The baffle plates 61 are arranged in a spiral shape, either continuously or discontinuously, or alternately in the vertical direction, inside the reaction vessel 11. The baffle plates 61 are preferably made of a wire mesh, a perforated steel plate, or the like, so that the ascending dioxide-containing gas can pass through them, but are not limited to these.

[0054] The presence of the baffle plate 61 lengthens the time it takes for the cementitious hardened material to fall within the reaction tank 11, thereby lengthening the time for countercurrent contact between the cementitious hardened material and the carbon dioxide-containing gas, thereby enabling more efficient fixation of carbon dioxide.

[0055] As shown in Fig. 3, the carbon dioxide fixation apparatus of the second modification is provided with agitation means 71 capable of agitating the cementitious hardened material contained in the reaction tank 11 and the carbon dioxide-containing gas supplied into the reaction tank 11. The agitation means 71 here is a rotor rotated by a rotary motor (not shown). The shape of the rotor is not limited. Note that the agitation means 71 only needs to be able to suitably agitate the cementitious hardened material contained in the reaction tank 11, and may be one that agitates by vibration, reciprocating motion, or the like.

[0056] Stirring by the stirring means 71 makes the atmosphere in the reaction tank 11 uniform, and also changes the area of ​​the cementitious hardened body that comes into contact with the carbon dioxide-containing gas, making it possible to fix carbon dioxide more efficiently.

[0057] The carbon dioxide fixation apparatus of the second modification further includes a fan 72 for making the carbon dioxide-containing gas supplied into the reaction tank 11 into a swirling flow. In this example, the fan 72 is provided midway through the gas supply pipe 33. By supplying the carbon dioxide-containing gas into the reaction tank 11 as a swirling flow, the cementitious hardened body is blown away and the contact area with the carbon dioxide-containing gas changes, which enables more efficient fixation of carbon dioxide.

[0058] The carbon dioxide fixation apparatus of the second modification further includes a fan 73 for making the water vapor supplied into reaction tank 11 a swirling flow. In this example, fan 73 is provided midway along water vapor supply pipe 54. Supplying water vapor into reaction tank 11 as a swirling flow also blows away the cementitious hardened body, changing the area that comes into contact with the carbon dioxide-containing gas, thereby enabling more efficient fixation of carbon dioxide.

[0059] The carbon dioxide fixation apparatus of the second modification may be provided with at least one of the stirring means 71 and the fans 72 and 73.

[0060] In addition, although not shown, in the carbon dioxide fixation apparatus which is a third modification, the reaction tank 11 is configured as a pressure-resistant container. This makes it possible to increase the pressure inside the reaction tank 11 by increasing the amount of carbon dioxide-containing gas and further water vapor supplied into the reaction tank 11. As a result, the carbon dioxide-containing gas further penetrates into the gaps in the cementitious hardened body inside the reaction tank 11. This ensures more reliable contact between them, enabling more efficient fixation of carbon dioxide.

[0061] Furthermore, the carbon dioxide fixation apparatus as a fourth modification includes vibration means (not shown) capable of vibrating the reaction tank 11. The vibration means causes the reaction tank 11 to reciprocate in one direction or in multiple directions, and the configuration thereof is not limited. By vibrating the reaction tank 11, the cementitious hardened body contained therein also vibrates, thereby changing the portion of the cementitious hardened body that comes into contact with the carbon dioxide-containing gas, thereby enabling more efficient fixation of carbon dioxide.

[0062] The present invention is not limited to the above-described embodiment and its modifications, and may be modified as appropriate within the scope of the claims. For example, multiple modifications may be combined. [Explanation of symbols]

[0063] 10...carbon dioxide fixation device, 11...reaction tank, 12...feeding port, 13...gas supply port, 14...exhaust port, 15...gas exhaust port, 16...steam supply port, 17...holding means, 20...cementitious hardened material supply device, 21...hopper, 22...metering feeder, 30...gas supply device, 31...gas storage tank, 32...flow rate controller, 33...gas supply pipe, 40...gas treatment device, 41...exhaust pipe, 42...pump, 43...dust collector, 50...steam supply device, 51...boiler, 52...steam heater, 53...flow rate controller, 54...steam supply pipe, 61...baffle, 71...stirring means, 72, 73...fan, 100...carbon dioxide fixation system.

Claims

1. A reaction vessel; an inlet provided at an upper portion of the reaction tank, through which the cementitious hardened material can be introduced into the reaction tank; a gas supply port provided at a lower portion of the reaction vessel and capable of supplying a carbon dioxide-containing gas into the reaction vessel; a gas outlet capable of discharging the carbon dioxide-containing gas obtained by the reaction of the cementitious hardened body with carbon dioxide to the outside of the reaction tank.

2. 2. The carbon dioxide fixation device according to claim 1, further comprising an outlet provided at a lower part of the reaction tank and capable of discharging the carbonated hardened cementitious material to the outside of the reaction tank.

3. 2. The carbon dioxide fixation device according to claim 1, further comprising a water vapor supply port capable of supplying water vapor into the reaction tank.

4. 2. The carbon dioxide fixation device according to claim 1, further comprising: a retaining means provided in a lower portion of the reaction tank, capable of retaining at least a portion of the introduced cementitious hardened body within the reaction tank.

5. 2. The carbon dioxide fixation apparatus according to claim 1, wherein a baffle plate inclined downward is provided inside the reaction tank.

6. 2. The carbon dioxide fixation device according to claim 1, further comprising a stirring means capable of stirring the cementitious hardened body introduced into the reaction tank and the carbon dioxide-containing gas supplied into the reaction tank.

7. 2. The carbon dioxide fixation apparatus according to claim 1, further comprising a fan capable of forming a swirling flow of the carbon dioxide-containing gas supplied into the reaction tank.

8. 2. The carbon dioxide fixation apparatus according to claim 1, wherein the reaction tank is configured as a pressure-resistant vessel.

9. 2. The carbon dioxide fixation device according to claim 1, further comprising a vibration means capable of vibrating the reaction tank.

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