Carbon dioxide fixation apparatus and carbon dioxide fixation method

Abstract

To provide an apparatus and a method for fixing carbon dioxide capable of fixing carbon dioxide by supplying a gas containing carbon dioxide having a concentration higher than that of the atmosphere to a cement-based waste material.SOLUTION: A carbon dioxide fixing apparatus 10 includes a container 20 having an inlet 24 and an outlet 26, a stirring device 30 for stirring a material containing a cement-based waste material supplied from the inlet 24 into the container 20 and sending the material to the outlet, and a supply device 40 for supplying a gas containing carbon dioxide at a concentration higher than that of the atmosphere into the container 20 while the material is stirred.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] The following Patent Document 1 describes a method for immobilizing carbon dioxide, in which material obtained by crushing waste concrete is collected and exposed to alternating dry and wet conditions for a predetermined period of time, thereby capturing and immobilizing carbon dioxide from the air into the material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-28581 Summary of the Invention [Problem to be solved by the invention]

[0004] In the carbon dioxide fixation method of Patent Document 1, atmospheric carbon dioxide is fixed in waste concrete. However, there has been a demand for fixation of carbon dioxide emitted from factories, power plants, etc. Such carbon dioxide is stored in, for example, gas tanks. Such gas tanks contain carbon dioxide at a concentration at least higher than that of the atmosphere.

[0005] In consideration of the above, the present invention provides a carbon dioxide fixation device and a carbon dioxide fixation method capable of supplying a gas containing carbon dioxide at a concentration higher than that of the atmosphere to cementitious waste material and fixating it. [Means for solving the problem]

[0006] The carbon dioxide fixation device of claim 1 comprises a container having an inlet and an outlet, a mixing device that mixes materials containing cement waste supplied from the inlet into the container and sends the materials to the outlet, and a supply device that supplies gas containing carbon dioxide at a concentration higher than that of the atmosphere into the container while the materials are being mixed.

[0007] The carbon dioxide fixation device of claim 1 can mix materials containing cement waste. Calcium oxide, the main component of cement, can adsorb and fix carbon dioxide as follows:

[0008] CaO+CO2 → CaCO3

[0009] By using the carbon dioxide fixation device of claim 1, cementitious waste material is exposed to carbon dioxide while being stirred, which allows a large amount of carbon dioxide to be fixed more quickly than when carbon dioxide is fixed in static cementitious waste material.

[0010] A carbon dioxide fixation apparatus according to a second aspect of the present invention is the carbon dioxide fixation apparatus according to the first aspect, wherein the agitator crushes the material while agitating it.

[0011] In the carbon dioxide fixation device of claim 2, the agitator crushes the material while stirring it. Crushing increases the surface area of ​​the cementitious waste material. This allows for faster and larger amounts of carbon dioxide fixation compared to when large cementitious waste material is added without being crushed. Furthermore, this method requires less labor than when large cementitious waste material is crushed beforehand and then added.

[0012] The carbon dioxide fixation device of claim 3 is the carbon dioxide fixation device of claim 2, wherein the agitator comprises a rotating shaft, a feed blade fixed to the rotating shaft that crushes the material and sends it toward the discharge outlet, and a return blade fixed to the rotating shaft that crushes the material and returns it toward the inlet.

[0013] In the carbon dioxide fixation device of claim 3, the agitator is equipped with a feed blade and a return blade. The feed blade and the return blade shear and crush the cementitious waste material. The return blade also increases the residence time of the cementitious waste material in the container, allowing it to be crushed into finer pieces.

[0014] A carbon dioxide fixation apparatus according to a fourth aspect of the present invention is the carbon dioxide fixation apparatus according to any one of the first to third aspects, wherein a plurality of partition walls projecting upward are provided on the inner peripheral surface of the lower part of the container.

[0015] Carbon dioxide has a higher specific gravity than other gases that make up air. Therefore, the carbon dioxide supplied to the container tends to accumulate at the bottom of the container and be sent to the outlet in accordance with the flow of cement waste.

[0016] Therefore, in the carbon dioxide fixation device of claim 4, a partition is provided on the inner peripheral surface of the lower part of the container to block the flow of carbon dioxide. When the cementitious waste material is stirred in this state, the carbon dioxide reaches the upper part of the container as well, and the cementitious waste material in the container can be evenly exposed to the carbon dioxide.

[0017] In the carbon dioxide fixation method of claim 5, a gas containing carbon dioxide at a concentration higher than that of the atmosphere is supplied into a container while a material containing cement waste is stirred by a stirring device inside the container.

[0018] According to the method for fixing carbon dioxide of claim 5, the cementitious waste material is exposed to carbon dioxide while being stirred, which allows a large amount of carbon dioxide to be fixed more quickly than when carbon dioxide is fixed in the cementitious waste material in a static state. [Effects of the Invention]

[0019] According to the present invention, a gas containing carbon dioxide at a concentration higher than that of the atmosphere can be supplied to and fixed in cement waste material. [Brief explanation of the drawings]

[0020] [Figure 1]FIG. 1A is a cross-sectional view showing a carbon dioxide fixation device according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along line BB in FIG. [Figure 2] FIG. 1A is a conceptual diagram showing the functions of a feed blade and a return blade in a carbon dioxide fixation device according to an embodiment of the present invention, and FIG. 1B is a conceptual diagram showing the functions of a partition wall. [Figure 3] Graph (A) shows an example of the amount of carbon dioxide fixed in a comparative example, graph (B) shows an example of the amount of carbon dioxide fixed of the present invention, and graph (C) shows another example of the amount of carbon dioxide fixed of the present invention. [Figure 4] 10 is a graph showing another example of the amount of fixed carbon dioxide in a comparative example. [Figure 5] 1 is a graph showing an example of the amount of fixed carbon dioxide when the average particle size of cement waste is 15 [mm] and when it is 2 [mm] or less. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, a carbon dioxide fixation device and a carbon dioxide fixation method according to an embodiment of the present invention will be described with reference to the drawings. Components indicated by the same reference numerals in the various drawings are the same components. However, unless otherwise specified in the specification, each component is not limited to one, and multiple components may be present.

[0022] Furthermore, descriptions of overlapping configurations and symbols in each drawing may be omitted. Note that the present disclosure is not limited to the following embodiments, and may be implemented by making appropriate modifications, such as omitting configurations, replacing them with different configurations, or combining one embodiment with various modified examples, within the scope of the purpose of the present disclosure.

[0023] <Carbon dioxide fixation device> 1 shows a carbon dioxide fixation device 10 according to an embodiment of the present invention. The carbon dioxide fixation device 10 includes a container 20, a stirring device 30, and a supply device 40.

[0024] (container) The container 20 includes a cylindrical main body 22, an inlet 24, and an outlet 26 provided in the main body 22. The inlet 24 is an upward opening provided at one end or a portion near the end of the main body 22. The outlet 26 is a downward opening provided at the other end or a portion near the end of the main body 22.

[0025] (Mixing device) The agitator 30 is a device that agitates the material supplied into the container 20 from the inlet 24 and sends it to the outlet 26. The agitator 30 can also crush the material supplied into the container 20 while stirring it.

[0026] A material capable of fixing carbon dioxide is used as the material to be supplied into the container 20. An example of such a material is cementitious waste material generated from ground improvement work, etc. A calcium compound (e.g., calcium oxide) contained in the cementitious waste material reacts chemically with carbon dioxide to produce calcium carbonate, thereby fixing the carbon dioxide.

[0027] In the present invention, the "material containing cement waste" may be a material containing aggregate, soil components, etc. in addition to such cement waste.

[0028] The agitator 30 includes a motor 32 provided outside the container 20, a rotary shaft 34 rotated by the motor 32, a feed blade 36, and a return blade 38. The rotary shaft 34 is provided inside the container 20, and both ends thereof are supported so as to protrude outside the container 20.

[0029] The rotating shaft 34 rotates about its axis when power is transmitted from the motor 32. The feed blade 36 and the return blade 38 are fixed to the rotating shaft 34 inside the container 20. A plurality of the feed blades 36 and the return blades 38 are fixed in the axial direction of the rotating shaft 34. In addition, a plurality of the feed blades 36 and the return blades 38 are fixed in the radial direction of the rotating shaft 34.

[0030] The feed blade 36 protrudes radially outward from the rotary shaft 34 and is curved toward the discharge port 26. As a result, as the feed blade 36 rotates around the rotary shaft 34, the cement waste material supplied into the container 20 is agitated and sent toward the discharge port 26.

[0031] On the other hand, the turning blade 38 protrudes radially outward from the rotating shaft 34 and is curved toward the inlet 24. As a result, as the turning blade 38 rotates around the rotating shaft 34, the cementitious waste material supplied into the container 20 is agitated and sent toward the inlet 24.

[0032] The feed blades 36 and the return blades 38 are detachably fixed to the rotary shaft 34. This allows the number and intervals of the feed blades 36 and return blades 38 to be adjusted.

[0033] For example, in order to send the cementitious waste material supplied into the container 20 to the discharge port 26, the number of feeding blades 36 is made greater than the number of turning blades 38. In this case, if the number of turning blades 38 is increased, the residence time of the cementitious waste material in the container 20 can be increased. On the other hand, if the number of turning blades 38 is reduced, the residence time of the cementitious waste material in the container 20 can be shortened.

[0034] (bulkhead) A plurality of partition walls 50 protruding upward are provided on the inner peripheral surface of the lower portion of the container 20. The partition walls 50 are plate members extending along the radial direction of the container 20, and a plurality of partition walls 50 are provided in the axial direction of the container 20.

[0035] The partition wall 50 is provided between the return blade 38 and the feed blade 36. Specifically, the partition wall 50 is provided between the return blade 38 and the feed blade 36 adjacent to the return blade 38 and provided on the discharge opening 26 side.

[0036] (Feeding device) The supply device 40 is a gas supply device capable of supplying gas into the container 20. The supply device 40 can supply gas sealed in a gas tank G into the container 20. As an example, the gas tank G contains a gas containing carbon dioxide at a concentration higher than that of the atmosphere. "Gas containing carbon dioxide at a concentration higher than that of the atmosphere" generally refers to a gas with a carbon dioxide concentration of 450 ppm or more.

[0037] The supply device 40 includes a control device 42, a sensor 44, and a supply pipe 46. The sensor 44 is a detector capable of measuring the concentration of carbon dioxide supplied into the container 20. The supply pipe 46 is a pipe having an end connected to a gas tank G.

[0038] A plurality of branch pipes 46A are connected to the supply pipe 46. The branch pipes 46A are connected to the main body 22 of the container 20. The branch pipes 46A are connected at intervals in the axial direction of the main body 22 over substantially the entire area between the inlet 24 and the outlet 26. Carbon dioxide can be supplied from the gas tank G to a plurality of locations in the container 20 via these branch pipes 46A.

[0039] The control device 42 can adjust the amount of carbon dioxide supplied from the gas tank G in accordance with the carbon dioxide concentration in the container 20 detected by the sensor 44.

[0040] For example, when the carbon dioxide concentration in the container 20 is below a predetermined value, the control device 42 supplies carbon dioxide from the gas tank G. Alternatively, the control device 42 increases the amount of carbon dioxide supplied from the gas tank G compared to when the carbon dioxide concentration in the container 20 is equal to or greater than a predetermined value. The amount of carbon dioxide supplied can be adjusted by opening and closing a solenoid valve (not shown).

[0041] On the other hand, when the carbon dioxide concentration in the container 20 is equal to or higher than the predetermined value, the control device 42 stops the supply of carbon dioxide from the gas tank G. Alternatively, the control device 42 reduces the amount of carbon dioxide supplied from the gas tank G compared to when the carbon dioxide concentration in the container 20 is lower than the predetermined value.

[0042] Furthermore, the control device 42 can adjust the amount of carbon dioxide supplied depending on the operating status of the motor 32 in the agitator 30.

[0043] For example, the controller 42 can supply carbon dioxide from the gas tank G while the agitator 30 is agitating and crushing the material in the vessel 20, i.e., while the motor 32 is running.

[0044] On the other hand, while the agitator 30 is not agitating and crushing the material in the container 20, i.e., while the motor 32 is not running, the control device 42 can stop the supply of carbon dioxide from the gas tank G.

[0045] The control by the control device 42 may be performed by an operator. For example, the operator can check the carbon dioxide concentration in the container 20 detected by the sensor 44, and adjust the amount of carbon dioxide supplied by opening and closing the valve of the gas tank G according to the check result. Similarly, the operator can adjust the amount of carbon dioxide supplied by opening and closing the valve of the gas tank G according to the operating status of the agitator 30.

[0046] <Method of carbon dioxide fixation> In the carbon dioxide fixation method according to the embodiment of the present invention, materials including cement waste are agitated and crushed in a container 20 by an agitator 30 (a return blade 38 and a feed blade 36).

[0047] As shown in Fig. 2(A), when the rotary shaft 34 is rotated, the feed blade 36 and the return blade 38 fixed to the rotary shaft rotate around the rotary shaft 34. The rotation of the feed blade 36 crushes the cementitious waste material put into the container 20. The crushed cementitious waste material moves in the direction indicated by the arrow F (towards the discharge port 26 shown in Fig. 1).

[0048] The moved cementitious waste material is crushed by the rotation of the return blade 38. Furthermore, part of the crushed cementitious waste material moves in the direction indicated by the arrow F, and part moves in the opposite direction to the direction indicated by the arrow F (towards the inlet 24), and is pushed back towards the feed blade 36.

[0049] The cementitious waste material pushed back toward the feed blade 36 is crushed by the rotation of the feed blade 36. In this way, and as shown by arrows K1 and K2, the cementitious waste material repeatedly moves toward the discharge outlet 26, moves in the opposite direction, and is crushed by the feed blade 36 and the return blade 38. As a result, the cementitious waste material gradually moves toward the discharge outlet 26, and its particle size becomes smaller.

[0050] At this time, the number of rotations per unit time of the rotating shaft 34 and the stirring time of the cementitious waste material in the container 20 are adjusted so that the average particle size of the cementitious waste material put into the container 20 is 2 mm or less.

[0051] For example, if the rotation speed of the rotating shaft 34 is set to 300 rpm, the mixing time can be set to 2 minutes and 20 seconds, so that the average particle size of the added cementitious waste material can be reduced to 2 mm or less. The added cementitious waste material has an unconfined compressive strength of 3.4 N / mm. 2 ] and is a cubic ground improvement body with a side length of 150 [mm].

[0052] In addition, in this carbon dioxide fixation method, a gas containing carbon dioxide at a concentration higher than that of the atmosphere is supplied into the container 20 while the cement waste is being agitated and crushed by the agitator 30. For example, the supply concentration and supply amount of carbon dioxide are adjusted so that the volume of carbon dioxide in the container 20 is about 10% of the volume of the gas in the container 20.

[0053] The carbon dioxide supplied to the container 20 flows through the lower space within the container 20 as shown by the arrow K3 in Figure 2(B). Since the container 20 is provided with a partition wall 50, the carbon dioxide remains behind the partition wall 50.

[0054] When the rotary shaft 34 is rotated, the feed blade 36 and the return blade 38 fixed to the rotary shaft 34 rotate, and the carbon dioxide is diffused upward along with the cementitious waste material that is lifted up.

[0055] <Action and effect> In the carbon dioxide fixation device 10 and carbon dioxide fixation method according to the embodiment of the present invention, materials containing cement waste can be agitated. Calcium oxide, which is the main component of cement, can adsorb and fix carbon dioxide as follows.

[0056] CaO+CO2 → CaCO3

[0057] Therefore, by using this carbon dioxide fixation device 10, the cementitious waste material is exposed to carbon dioxide while being stirred. This allows a large amount of carbon dioxide to be fixed more quickly than when carbon dioxide is fixed in static cementitious waste material.

[0058] For example, the comparative example in Figure 3(A) shows the amount of carbon dioxide fixation according to particle size when cement waste is left to stand for 10 minutes in a container with a carbon dioxide concentration of 10%.

[0059] On the other hand, an example of the present invention shown in Figure 3(B) shows the amount of carbon dioxide fixation according to particle size when cement waste is stirred and crushed for 2 minutes and 40 seconds in a container 20 with a carbon dioxide concentration of 13%.

[0060] Comparing the comparative example in FIG. 3(A) with the present invention in FIG. 3(B), the amount of carbon dioxide fixed in cementitious waste material with an average particle size of 2 mm or less in the present invention (amount fixed per ton of cementitious waste material: approximately 40 kg / t) is greater than the amount fixed in cementitious waste material with an average particle size of 2 mm or less that was left to stand for 10 minutes (approximately 32 kg / t), despite the short mixing time of 2 minutes and 40 seconds.

[0061] In addition, an example of the present invention shown in Figure 3(C) shows the amount of carbon dioxide fixation according to particle size when cement waste is stirred and crushed for 2 minutes and 40 seconds in a container 20 with a carbon dioxide concentration of 5%.

[0062] Comparing the comparative example in Figure 3(A) with the present invention in Figure 3(C), the amount of carbon dioxide fixed in cement waste with an average particle size of 2 [mm] or less in the present invention (approximately 36 [kg / t]) is greater than the amount fixed in cement waste with an average particle size of 2 [mm] or less that was left to stand for 10 minutes (approximately 32 [kg / t]), despite the short mixing time of 2 minutes 40 seconds and the low carbon dioxide concentration environment of 5 [%].

[0063] In addition, the comparative example in Figure 4 shows the amount of carbon dioxide fixation depending on the curing time when cement waste with an average particle size of 2 mm is left to stand in a container with a carbon dioxide concentration of 30%.

[0064] Comparing the comparative example in Figure 4 with the present invention in Figure 3(B), the amount of carbon dioxide fixed in cementitious waste material with a particle size of 2 [mm] or less in the present invention (approximately 40 [kg / t]) is equivalent to the amount fixed in cementitious waste material left to stand for 120 minutes at a high concentration of 30 [%], despite being mixed for a short time of 2 minutes and 40 seconds at a low concentration of 13 [%].

[0065] In the carbon dioxide fixation apparatus 10 according to the embodiment of the present invention, the agitator 30 crushes the cement waste while agitating it.

[0066] By crushing the cementitious waste material, the surface area of ​​the cementitious waste material (the total surface area of ​​the cementitious waste material put into the container 20) increases. Therefore, a large amount of carbon dioxide can be fixed more quickly than when large cementitious waste material is put in and not crushed. In addition, the labor required is reduced compared to when large cementitious waste material is crushed in advance and then put in.

[0067] For example, Figure 5 shows the amount of carbon dioxide fixed (amount fixed per ton of cement waste) when the average particle size of cement waste is 15 mm and when it is 2 mm or less. As shown in this figure, the amount of carbon dioxide fixed can be increased by crushing the waste to reduce the particle size.

[0068] Furthermore, the amount of carbon dioxide emitted by the operation of the agitator 30 is greater when the average particle size of the cement waste is 2 mm or less than when it is 15 mm. However, even when this amount of emission is taken into account, the amount of carbon dioxide fixed is greater when the average particle size is smaller.

[0069] 2(A), the agitator 30 of the carbon dioxide fixation apparatus 10 according to the embodiment of the present invention is equipped with a feed blade 36 and a return blade 38. The feed blade 36 and the return blade 38 shear and crush the cementitious waste. The return blade 38 also increases the residence time of the cementitious waste in the container 20, allowing it to be crushed into finer pieces.

[0070] Furthermore, in the carbon dioxide fixation device 10 according to the embodiment of the present invention, a partition wall 50 is provided on the inner peripheral surface of the lower part of the container 20, thereby blocking the flow of carbon dioxide supplied into the container 20 from the inlet 24 to the outlet 26. When the container 20 is stirred together with the cementitious waste in this state, the carbon dioxide reaches the upper part of the container 20 as well, and the cementitious waste in the container 20 can be evenly exposed to the carbon dioxide.

[0071] <Other embodiments> In the above embodiment, the agitator 30 crushes the cementitious waste while stirring it, but the present invention is not limited to this. For example, the agitator 30 does not have to crush the cementitious waste. In this case, cementitious waste that has been crushed to a predetermined size in advance can be charged into the container 20.

[0072] In the above embodiment, the agitator 30 is provided with the feed blade 36 and the return blade 38, but the present invention is not limited to this. For example, if the cement waste is not to be crushed, the return blade 38 may be omitted and only the feed blade 36 may be provided.

[0073] In the above embodiment, a plurality of partition walls 50 protruding upward are provided on the lower inner peripheral surface of the container 20, but the embodiment of the present invention is not limited to this. For example, even if such partition walls 50 are not provided, when cementitious waste is stirred in the container 20, carbon dioxide is also stirred along with the stirred cementitious waste.

[0074] Furthermore, although the branch pipe 46A of the supply pipe 46 is connected to multiple locations on the main body 22 of the container 20 over substantially the entire area between the inlet 24 and the outlet 26, the embodiment of the present invention is not limited to this.

[0075] For example, the supply pipe 46 may be connected at least to a portion of the main body 22 that is closer to the outlet 26. This difference may be achieved by providing, for example, a branch pipe 46A to connect to multiple locations, or by connecting to one location without providing a branch pipe 46A.

[0076] Since the particle size of the cement waste material is smaller in the portion of the main body 22 closer to the outlet 26 than in the portion closer to the inlet 24, carbon dioxide can be fixed efficiently.

[0077] In the above embodiment, the number of rotations per unit time of the rotating shaft 34 and the stirring time of the cementitious waste material in the container 20 are adjusted so that the average particle size of the cementitious waste material introduced into the container 20 is 2 mm or less, but the embodiment of the present invention is not limited to this. The average particle size of the introduced cementitious waste material can be arbitrarily determined and can be appropriately determined.

[0078] Furthermore, in the above embodiment, the amount of carbon dioxide supplied is adjusted so that the volume of carbon dioxide in container 20 is about 10% of the volume of the gas in container 20, but the present invention is not limited to this embodiment. This concentration is arbitrary, as long as the carbon dioxide concentration in the gas supplied to container 20 is higher than the carbon dioxide concentration contained in the atmosphere. As such, the present invention can be embodied in various aspects. [Explanation of symbols]

[0079] 10 Carbon dioxide fixation device 20 containers 24 Inlet 26 Outlet 30 Stirring device 34 Rotation axis 36 Feed blade 38 Turning Blade 40 Feeding device

Claims

1. a container having an inlet and an outlet; a mixing device that mixes the material containing the cement waste material supplied from the inlet into the container and sends the material to the outlet; a supply device that supplies a gas containing carbon dioxide at a concentration higher than that of atmospheric carbon dioxide into the container while the material is being stirred; A carbon dioxide fixation device equipped with the device.

2. The stirring device crushes the material while stirring it. The carbon dioxide fixation device according to claim 1 .

3. The stirring device is A rotation axis; a feed blade fixed to the rotary shaft for crushing the material and feeding the material toward the discharge port; A return blade fixed to the rotary shaft for crushing the material and returning it toward the inlet side; Equipped with The carbon dioxide fixation device according to claim 2.

4. A plurality of partition walls protruding upward are provided on the lower inner peripheral surface of the container. The carbon dioxide fixation device according to any one of claims 1 to 3.

5. While stirring materials including cement waste with a stirring device inside the container, supplying a gas containing carbon dioxide at a concentration higher than atmospheric into the container; Carbon dioxide fixation method.

Images