Carbon dioxide absorbent, carbon dioxide absorption equipment, carbon dioxide absorption method, and method for producing carbon dioxide absorbent

Abstract

To provide a carbon dioxide absorbent capable of absorbing carbon dioxide at a low cost without imparting a load to the environment, and also to provide a carbon dioxide absorption facility, a carbon dioxide absorption method and a manufacturing method of a carbon dioxide absorbent.SOLUTION: A carbon dioxide absorbent is for absorbing carbon dioxide included in a gas. The carbon dioxide absorbent includes a biomass combustion ash being a combustion ash of biomass. The biomass combustion ash includes a calcium oxide. The carbon dioxide absorbent is a granular material, and includes the biomass combustion ash and a binder. The binder includes a calcium sulfate. The binder may be a gypsum. The gypsum may be a desulfurization gypsum.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a carbon dioxide absorbent, a carbon dioxide absorption facility, a carbon dioxide absorption method, and a method for producing a carbon dioxide absorbent. [Background technology]

[0002] In recent years, as one of the measures against global warming, there has been a demand for reducing carbon dioxide emissions from facilities that use fossil fuels. In order to reduce carbon dioxide emissions resulting from the combustion of fossil fuels, it is necessary not only to improve the thermal efficiency of plants but also to advance the development of carbon dioxide capture and storage (CCS) technology, and technological development for this purpose is being advanced. For example, Patent Document 1 discloses a carbon dioxide absorption method in which carbonate ions generated in a desulfurization device of a thermal power plant are combined with an alkaline earth metal or an alkali metal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-30840 A Summary of the Invention [Problem to be solved by the invention]

[0004] The carbon dioxide absorption method of Patent Document 1 uses a large amount of alkaline earth metal or alkali metal, and these substances are difficult to obtain in large quantities at low cost. In addition, these substances have the problem of a large environmental load when disposed of. Such a problem is not limited to the case of absorbing carbon dioxide from exhaust gas generated by the turbine of a thermal power plant, but also exists in the case of absorbing carbon dioxide from exhaust gas in other combustion devices.

[0005] The present invention has been made against this background, and has an object to provide a carbon dioxide absorbent, a carbon dioxide absorption facility, a carbon dioxide absorption method, and a method for producing a carbon dioxide absorbent that are capable of absorbing carbon dioxide at low cost without imposing a load on the environment. [Means for solving the problem]

[0006] In order to achieve the above object, the carbon dioxide absorbent according to the present invention comprises: Absorbs carbon dioxide contained in gas do A carbon dioxide absorbent comprising: Biomass combustion ash is the ash from the combustion of biomass. and a binder the biomass combustion ash comprises calcium oxide; The carbon dioxide absorbent is The biomass combustion ash is aggregated by the binder. It is a granular material. 、 before The binder includes calcium sulfate. Effect of the Invention

[0007] According to the present invention, it is possible to provide a carbon dioxide absorbent, a carbon dioxide absorption facility, a carbon dioxide absorption method, and a method for producing a carbon dioxide absorbent that are capable of absorbing carbon dioxide at low cost without imposing a burden on the environment. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing a configuration of a thermal power plant according to a first embodiment of the present invention. [Diagram 2] FIG. 1 is a diagram showing a configuration of a carbon dioxide absorption facility according to a first embodiment of the present invention. [Diagram 3] FIG. 11 is a diagram showing a configuration of a carbon dioxide absorption facility according to a second embodiment of the present invention. [Figure 4] FIG. 11 is a diagram showing a configuration of a thermal power plant according to a modified example of the present invention. [Diagram 5] FIG. 1 is a diagram showing the results of a fluorescent X-ray measurement of chicken manure incineration ash to which water has been added in an example. [Figure 6]1 is a graph showing the results of X-ray diffraction measurement of chicken manure incineration ash to which water has been added in an example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a carbon dioxide absorbent, a carbon dioxide absorption facility, a carbon dioxide absorption method, and a method for manufacturing a carbon dioxide absorbent according to embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same or equivalent parts are denoted by the same reference numerals.

[0010] (Embodiment 1) A carbon dioxide absorbent, a carbon dioxide absorption facility, a carbon dioxide absorption method, and a method for manufacturing a carbon dioxide absorbent according to a first embodiment will be described with reference to Fig. 1 and Fig. 2. The carbon dioxide absorbent absorbs carbon dioxide contained in a gas by a chemical reaction with carbon dioxide. The carbon dioxide absorbent is housed, for example, in a carbon dioxide absorption facility, absorbs carbon dioxide in a gas taken into the carbon dioxide absorption facility, and changes the gas into a treated gas from which carbon dioxide has been removed. The carbon dioxide absorption facility is installed, for example, in an exhaust system that discharges exhaust gas derived from fossil fuels generated in a thermal power plant or a steelworks, and changes the exhaust gas into a treated gas.

[0011] The carbon dioxide absorbent according to the first embodiment is produced from combustion ash (biomass combustion ash) obtained by incinerating biomass and water. Biomass combustion ash contains calcium oxide CaO, and calcium hydroxide Ca(OH)2 is produced by adding water to calcium oxide. When calcium hydroxide comes into contact with carbon dioxide CO2, a chemical reaction occurs between the two to produce calcium carbonate CaCO3. This chemical reaction allows the absorption of carbon dioxide (carbonate ions) in the exhaust gas.

[0012] The amount of calcium oxide contained in the carbon dioxide absorbent depends on the type of biomass, and may be set to an appropriate value in consideration of economic efficiency and the reaction efficiency of carbon dioxide absorption. Note that calcium carbonate produced after the absorption of carbon dioxide by the carbon dioxide absorbent may be effectively utilized in the same applications as other industrially produced calcium carbonate.

[0013] The biomass is preferably biomass containing a large amount of calcium compounds that are converted to calcium oxide when burned. The combustion temperature of the biomass is a temperature at which calcium compounds are converted to calcium oxide, for example, within the range of 800° C. to 1500° C., and more preferably about 1000° C. Examples of biomass include wood, livestock manure, sewage sludge, and agricultural residues.

[0014] Of these, livestock manure, particularly that from eggs, contains many calcium compounds that are converted to calcium oxide at combustion temperatures of around 1000° C., making it suitable as a raw material for carbon dioxide absorbents. This is because livestock manure, particularly that from eggs, contains calcium compounds that were not completely digested in the livestock's bodies and calcium compounds that were excreted after digestion, as the livestock are fed feed that contains a lot of calcium.

[0015] Char (charcoal-like unburned matter) obtained by burning wood in a gasifier also contains about 50% calcium oxide by weight, making it suitable as a raw material for carbon dioxide absorbents. On the other hand, livestock bones contain a lot of calcium phosphate and apatite, and these calcium compounds do not change to calcium oxide even at combustion temperatures of 1000°C or higher, making them unsuitable as a raw material for carbon dioxide absorbents.

[0016] The carbon dioxide absorbent according to the first embodiment is a slurry (wet absorbent) formed from biomass combustion ash and water. The slurry is produced by mixing biomass combustion ash with water and stirring with a mixer, and contains calcium hydroxide produced by the reaction of calcium oxide with water. The weight ratio of the biomass combustion ash to water in the slurry is, for example, 1:1.

[0017] The amount of water added to the biomass combustion ash is the amount required to convert the calcium oxide in the biomass combustion ash into calcium hydroxide. For example, the theoretical amount of water required to convert the calcium oxide in 1 kilogram of biomass combustion ash into calcium hydroxide is approximately 1.6 L at maximum at a temperature of 20°C, calculated from the solubility of calcium oxide. However, in the actual slurry production process, water is added at a temperature of several tens of degrees Celsius to continuously react with calcium oxide, so it is sufficient to add less water than this theoretical amount to the biomass combustion ash.

[0018] Calcium hydroxide is industrially produced by crushing limestone, burning it with fossil fuel to produce calcium oxide, and adding water to the calcium oxide, whereas biomass combustion ash containing calcium hydroxide is produced by incineration at a biomass-fired power plant or biomass incineration facility. Biomass combustion is carbon neutral, as it does not use fossil fuels and is not counted as carbon dioxide emissions. In addition, biomass combustion ash has a low environmental impact because it is made from naturally occurring biomass and does not contain substances such as alkaline earth metals or alkali metals.

[0019] In addition, biomass combustion ash obtained from biomass combustion facilities such as biomass thermal power plants and biomass heat supply boilers has the following advantages. First, biomass combustion ash is a by-product of power generation and heat supply, so it can be obtained at low cost. In addition, biomass combustion facilities are carbon-neutral power sources that do not use fossil fuels, and are expected to become more widespread in the future, so a stable supply of biomass incineration ash can be expected. Furthermore, carbon dioxide absorbents generated from combustion ash from biomass combustion facilities can be used to absorb carbon dioxide in industrial facilities that use fossil fuels, such as thermal power plants, heat supply boilers, or steelmaking facilities, thereby reducing carbon dioxide emissions from the entire industry.

[0020] Next, a configuration of the carbon dioxide absorbing equipment 10 according to the embodiment 1 will be described. The following describes an example in which carbon dioxide is absorbed in exhaust gas discharged from a thermal power plant.

[0021] As shown in FIG. 1, the carbon dioxide absorption equipment 10 is connected to an exhaust system of a thermal power plant 1 and removes carbon dioxide from exhaust gas generated in a boiler 4. In addition to the carbon dioxide absorption equipment 10, the thermal power plant 1 further includes a generator 2 that generates electricity, a turbine 3 that rotates the generator 2, a boiler 4 that supplies steam to the turbine 3, a denitrification device 5 that removes nitrogen oxides from the exhaust gas generated in the boiler 4, an electrostatic precipitator 6 that removes dust from the exhaust gas generated in the boiler 4, a desulfurization device 7 that removes sulfur oxides from the exhaust gas generated in the boiler 4, and a chimney 8 that releases the exhaust gas generated in the boiler 4 into the atmosphere. The boiler 4 is an example of a combustion device that burns fuel, and includes a combustion chamber 4a that burns fuel, and a heat exchanger 4b that is disposed inside the combustion chamber 4a and generates steam by burning the fuel.

[0022] The rotating shaft of the turbine 3 is mechanically connected to the rotating shaft of the generator 2, and the heat exchanger 4b of the boiler 4 is connected to the turbine 3 by piping through which water steam can flow. In addition, the combustion chamber 4a of the boiler 4, the denitrification device 5, the electrostatic precipitator 6, the desulfurization device 7, the carbon dioxide absorption equipment 10, and the chimney 8 are connected in series by piping through which exhaust gas can flow.

[0023] The carbon dioxide absorption equipment 10 accommodates a carbon dioxide absorbent therein, and causes the carbon dioxide in the exhaust gas supplied from the outside to be absorbed by the carbon dioxide absorbent before being discharged to the outside. The carbon dioxide absorption equipment 10 has, for example, the same or equivalent configuration as the desulfurization equipment 7. The desulfurization equipment 7 is classified into a wet desulfurization equipment that uses a slurry containing calcium carbonate to absorb sulfide oxides, and a dry desulfurization equipment that uses granular material containing calcium carbonate. By making the carbon dioxide absorption equipment 10 have the same or equivalent configuration as the desulfurization equipment 7 already installed in the thermal power plant, the costs required for installation and maintenance of the carbon dioxide absorption equipment 10 can be suppressed. In the first embodiment, since the carbon dioxide absorbent is a slurry, a case will be described as an example in which the carbon dioxide absorption equipment 10 is a wet carbon dioxide absorption equipment.

[0024] In the carbon dioxide absorption equipment 10, a slurry of biomass combustion ash containing calcium hydroxide (carbon dioxide absorbent) is sprayed onto the exhaust gas taken into the tank, thereby absorbing the carbon dioxide contained in the exhaust gas.

[0025] As shown in Fig. 2, the carbon dioxide absorption equipment 10 includes an absorption tower 11 that receives a slurry, a gas supply pipe 12 that supplies an exhaust gas to the absorption tower 11, a gas discharge pipe 13 that discharges a treated gas from which carbon dioxide has been removed from the absorption tower 11, a slurry storage tank 14 in which the slurry is stored, a slurry supply pump 15 that supplies the slurry from the slurry storage tank 14 to the absorption tower 11, a spray pipe 16 that discharges the slurry into the absorption tower 11, a circulation pump 17 that recovers the slurry discharged into the absorption tower 11 and circulates it back into the absorption tower 11, and a slurry discharge pipe 18 that discharges the slurry to the outside of the absorption tower 11. The absorption tower 11 is provided with a backflow prevention plate 11a, which is an example of a tank that contains a carbon dioxide absorbent, and which prevents the slurry discharged downward from the spray pipe 16 from flowing backward. The backflow prevention plate 11a has a large number of holes formed therein through which the exhaust gas can pass.

[0026] 2, solid arrows indicate the flow of slurry, and dotted arrows indicate the flow of gas. In carbon dioxide absorption equipment 10, slurry, which is a carbon dioxide absorbent, is sprayed from spray pipes 16 onto exhaust gas taken into absorber tower 11 from boiler 4. During operation of the thermal power plant, slurry is constantly discharged from spray pipes 16 into absorber tower 11, and part of the slurry after reaction is circulated by circulation pump 17 so as to return to absorber tower 11 again, while the remainder is constantly discharged from slurry discharge pipe 18 to the outside of absorber tower 11. The carbon dioxide absorption facility 10 has the above configuration.

[0027] Next, the flow of the carbon dioxide absorbing method carried out using the carbon dioxide absorbing equipment 10 according to the first embodiment will be described.

[0028] First, the carbon dioxide absorbent is supplied into the absorption tower 11 (supply step). Specifically, the slurry supply pump 15 is operated to release the slurry from the spray pipe 16 into the absorption tower 11.

[0029] Next, exhaust gas containing carbon dioxide is contacted with the carbon dioxide absorbent supplied inside the absorption tower 11 (contact step). By supplying exhaust gas from the gas supply pipe 12 into the absorption tower 11, the slurry discharged from the spray pipe 16 comes into contact with the exhaust gas supplied from the gas supply pipe 12, and calcium hydroxide contained in the slurry reacts with carbon dioxide to change into calcium carbonate.

[0030] Next, the carbon dioxide absorbent that has come into contact with the exhaust gas containing carbon dioxide, i.e., the carbon dioxide absorbent containing calcium carbonate, is removed from the absorption tower 11 (removal step). Specifically, a part of the post-reaction slurry containing calcium carbonate is discharged to the outside from the absorption tower 11 through a slurry discharge pipe 18, and the other slurry is discharged into the absorption tower 11 from a spray pipe 16 through a circulation pump 17. Note that each step is performed in parallel in the carbon dioxide absorption equipment 10. The flow of the carbon dioxide absorption method carried out using the carbon dioxide absorption equipment 10 has been described above.

[0031] As described above, the carbon dioxide absorbent according to the first embodiment is a carbon dioxide absorbent for absorbing carbon dioxide contained in gas, and contains biomass combustion ash, which is the combustion ash of biomass, and the biomass combustion ash contains calcium oxide. Therefore, the carbon dioxide absorbent can absorb carbon dioxide in exhaust gas at low cost without imposing a large burden on the environment.

[0032] Moreover, the carbon dioxide absorbent according to the first embodiment is a slurry containing biomass combustion ash and water. Therefore, the absorption of carbon dioxide in the exhaust gas can be realized by using a wet-type carbon dioxide absorption facility 10 having the same or similar configuration as the wet-type desulfurization device 7.

[0033] (Embodiment 2) A carbon dioxide absorbent, a carbon dioxide absorption facility, a carbon dioxide absorption method, and a carbon dioxide absorbent manufacturing method according to the second embodiment will be described with reference to Fig. 3. The carbon dioxide absorbent according to the first embodiment is a slurry, whereas the carbon dioxide absorbent according to the second embodiment is a granular material (dry absorbent). The following description will focus on the differences between the two.

[0034] The carbon dioxide absorbent according to the second embodiment is a granular material mainly composed of biomass combustion ash. The granular material of the carbon dioxide absorbent is produced by adding a binder and, if necessary, water to the biomass combustion ash, mixing them, and forming them. The binder serves to aggregate the particles of the biomass combustion ash. The granular material may be subjected to steam curing in order to develop strength quickly.

[0035] The granular body is, for example, a pellet. A pellet is a granular body compressed and molded into a cylindrical shape by extrusion granulation (pellet granulation) or press molding. In extrusion granulation, for example, a binder and water are added to biomass combustion ash and kneaded in a kneader, and then the kneaded material is passed through a number of holes formed in a plate and cut to a certain length with a cutter to form a cylindrical granular body.

[0036] The amount of water required for pellet molding is, for example, within a range of 0% to 40% by weight, taking into consideration the ease of molding and the strength of the pellets. In press molding, the amount is preferably within a range of 0% to 15%, and in extrusion granulation, the amount is preferably within a range of 30% to 40%. Note that, at the time when the granular carbon dioxide absorbent is caused to absorb carbon dioxide, the calcium oxide in the granular body can be changed to calcium hydroxide by contacting the granular body with water, so that it is not necessary to change all of the calcium oxide to calcium hydroxide when the granular body is molded.

[0037] The binder includes gypsum, cement, soda ash, clay, or an organic polymer such as alginic acid or polyvinyl alcohol. The binder is preferably a binder containing calcium sulfate, and is preferably gypsum. As the gypsum, it is preferable to use desulfurized gypsum produced by a dry or wet desulfurization method.

[0038] Next, the configuration of the carbon dioxide absorption equipment 20 according to the second embodiment will be described. The carbon dioxide absorption equipment 20 is a dry type carbon dioxide absorption equipment that absorbs carbon dioxide contained in the exhaust gas by bringing the exhaust gas taken in therein into contact with a granular carbon dioxide absorbent. The carbon dioxide absorption equipment 20 is connected to the exhaust system of the thermal power plant 1 in the same manner as the carbon dioxide absorption equipment 10, and may be connected between the desulfurization equipment 7 and the chimney 8 via a pipe, for example.

[0039] 3, the carbon dioxide absorption equipment 20 includes an absorption tower 21 filled with granular material (e.g., pellets), a gas supply pipeline 22 that supplies exhaust gas to the inside of the absorption tower 21, a gas discharge pipeline 23 that discharges treated gas from which carbon dioxide has been removed from the absorption tower 21 to the outside, a water supply pipeline 24 that supplies water to the inside of the absorption tower 21, a pump 25 installed in the water supply pipeline 24 and pumps out the water in the water supply pipeline 24, and a water discharge pipeline 26 that discharges water from the absorption tower 21 to the outside. The gas supply pipeline 22, the gas discharge pipeline 23, the water supply pipeline 24, and the water discharge pipeline 26 are each connected to the absorption tower 21.

[0040] The absorption tower 21 is an example of a tank that stores a carbon dioxide absorbent. Inside the absorption tower 21, a fall prevention plate 21a is provided to prevent the granular material from falling downward. The fall prevention plate 21a has a large number of holes formed therein that prevent the granular material from passing through. In addition, the absorption tower 21 is provided at its upper part with an inlet (not shown) that can be opened and closed to input the granular material, and at its lower part with an outlet (not shown) through which the granular material can be discharged.

[0041] The gas supply pipe 22 is connected to the bottom side of the absorption tower 21 relative to the fall prevention plate 21a, and the gas discharge pipe 23 is connected to the upper side of the absorption tower 21. In addition, the water supply pipe 24 is connected to the upper side of the absorption tower 21, and the water discharge pipe 26 is connected to the fall prevention plate 21a of the absorption tower 21 and the bottom side of the gas supply pipe 22.

[0042] In Fig. 3, solid arrows indicate the flow of water, and dotted arrows indicate the flow of gas. Water supplied from water supply pipe 24 falls in a spray-like manner toward the granular material packed in absorption tower 21, comes into contact with the granular material, converts the calcium oxide in the granular material to calcium hydroxide, and is then discharged from water discharge pipe 26 located below. In addition, exhaust gas introduced into absorption tower 21 from gas supply pipe 22 flows from the bottom to the top of absorption tower 21, and is converted into a treated gas from which carbon dioxide has been removed by aeration through the granular material, and is discharged to the outside from gas discharge pipe 23. The granular material that has reacted with carbon dioxide may be periodically removed from a discharge port (not shown) on the bottom of absorption tower 21, and new granular material may be introduced from an inlet on the top of absorption tower 21. The carbon dioxide absorption facility 20 has the above configuration.

[0043] As described above, the carbon dioxide absorbent according to the second embodiment is a granular material and contains biomass combustion ash and a binder. Therefore, the absorption of carbon dioxide in the exhaust gas can be realized using the dry carbon dioxide absorption equipment 20 that is the same as or similar to the dry desulfurization device 7.

[0044] The present invention is not limited to the above-described embodiment, and the following modifications are possible.

[0045] (Modification) In the above embodiment, the carbon dioxide absorption equipment 10, 20 is installed between the desulfurization equipment 7 and the chimney 8, but the present invention is not limited to this. The carbon dioxide absorption equipment 10, 20 may be installed at any position in the exhaust system of a thermal power plant. For example, the carbon dioxide absorption equipment 10, 20 may be installed between the electrostatic precipitator 6 and the desulfurization equipment 7.

[0046] In the above embodiment, the carbon dioxide absorption facilities 10 and 20 are installed separately from the desulfurization facility 7, but the present invention is not limited to this. For example, in a thermal power plant as shown in Fig. 4, an existing desulfurization facility 7 may be used as a carbon dioxide absorption facility, or the existing desulfurization facility 7 may be modified and used as a carbon dioxide absorption facility.

[0047] For example, if the desulfurization device 7 is a wet type desulfurization device, a slurry of calcium carbonate for desulfurization may be mixed with biomass combustion ash for carbon dioxide absorption, and this slurry may be sprayed onto the exhaust gas in the tank of the desulfurization device 7. Also, if the desulfurization device 7 is a dry type desulfurization device, pellets made from biomass combustion ash may be packed into the inside of the existing absorption tower of the desulfurization device 7 together with the calcium carbonate pellets for desulfurization. With this method, there is no need to install new equipment at the thermal power plant 1, and therefore the cost associated with carbon dioxide absorption can be further reduced.

[0048] In the above-mentioned second embodiment, pellets are produced as the granular bodies, but the present invention is not limited to this. The granular bodies may be produced by a granulation method other than the extrusion granulation method, for example, a rolling granulation method or an agitation granulation method.

[0049] In the above embodiment, the carbon dioxide absorption method starts with a step of discharging a slurry containing biomass incineration ash into the absorption tower 11, but the present invention is not limited to this. For example, the carbon dioxide absorption method may include a step (production step) of producing a carbon dioxide absorbent from biomass combustion ash discharged at a biomass thermal power plant that burns biomass to generate power. In addition, the carbon dioxide absorption method may include a step (power generation step) of burning biomass at a biomass thermal power plant to generate power prior to the production step. In biomass thermal power generation, all or part of the fuel contains biomass, and power is generated by burning the fuel containing biomass using the same principle as thermal power generation using fossil fuels.

[0050] In the above embodiment, calcium carbonate produced after the absorption of carbon dioxide by the carbon dioxide absorbent is effectively used for the same purpose as industrially produced calcium carbonate, but the present invention is not limited to this. For example, calcium carbonate produced after the absorption of carbon dioxide may be mixed with fly ash and calcium sulfate to create an algae reef, which may then be placed underwater and seaweed or seaweed may be attached to it to fix carbon dioxide by the seaweed or seaweed.

[0051] In the above embodiment, the carbon dioxide absorption equipment is applied to a thermal power plant, but the present invention is not limited to this. The equipment may be applied to other facilities that emit carbon dioxide, such as steel mills, oil refineries, and waste incineration plants.

[0052] The above-mentioned embodiments are merely examples, and the present invention is not limited to these, and various embodiments are possible without departing from the spirit of the invention described in the claims. The components described in each embodiment and modification can be freely combined. In addition, inventions equivalent to the inventions described in the claims are also included in the present invention.

[0053] The present invention will be specifically described below with reference to examples, although the present invention is not limited to these examples.

[0054] (Example) In the examples, a test was carried out to verify whether carbon dioxide is absorbed by biomass combustion ash. The biomass combustion ash was chicken manure ash generated by burning chicken manure at 1100°C for 1 hour. The ash content of the chicken manure ash was about 20% when calculated from the loss on ignition. In addition, 55% (by weight) of the chicken manure ash was calcium oxide. The same weight of water was added to the biomass combustion ash and thoroughly stirred to generate a slurry. Carbon dioxide was aerated into this slurry using an experimental device, and the chemical composition of the slurry before and after the aeration of carbon dioxide was analyzed using an X-ray fluorescence analyzer and an X-ray diffraction device.

[0055] The results of the fluorescent X-ray measurement are shown below. As shown in Figure 5, before the aeration of carbon dioxide, the elemental weight percentages of carbon and oxygen in the slurry were 1.5% and 39.8%, respectively, whereas after the aeration of carbon dioxide, they increased to 2.5% and 45.6%, respectively. This is thought to be because calcium hydroxide in the slurry reacted with carbon dioxide to produce calcium carbonate, which contains carbon and oxygen atoms.

[0056] Next, the results of the X-ray measurement are shown. The upper waveform in Figure 6 shows the measurement data of chicken manure ash, and the lower waveform shows the measurement data of chicken manure ash to which water was added and carbon dioxide was aerated. As shown in Figure 6, before the aeration of carbon dioxide, a calcium oxide peak and an apatite peak were present, whereas after the aeration of carbon dioxide, a calcium carbonate peak appeared. This means that calcium carbonate was formed as a result of the calcium oxide in the combustion ash absorbing carbon dioxide. From the above, it was confirmed that carbon dioxide is absorbed by biomass combustion ash. [Explanation of symbols]

[0057] 1. Thermal power plants 10,20 Carbon dioxide absorption equipment 11,21 Absorption tower 12,22 Gas supply pipeline 13,23 Gas exhaust pipe

Claims

1. A carbon dioxide absorbent that absorbs carbon dioxide contained in a gas, The present invention includes biomass combustion ash, which is combustion ash of biomass, and a binder, the biomass combustion ash including calcium oxide, The carbon dioxide absorbent is a granular material in which the biomass combustion ash is aggregated by the binder, The binder comprises calcium sulfate. Carbon dioxide absorbent.

2. The binder is gypsum. The carbon dioxide absorbent according to claim 1.

3. The gypsum is desulfurized gypsum. The carbon dioxide absorbent according to claim 2.

4. The biomass includes at least one of wood, livestock manure, sewage sludge, and agricultural residues; The carbon dioxide absorbent according to any one of claims 1 to 3.

5. A carbon dioxide absorption facility connected to an exhaust system of a combustion device, A tank that accommodates the carbon dioxide absorbent according to any one of claims 1 to 4; a gas supply line connected to the tank and supplying exhaust gas from the combustion device to the inside of the tank; a gas exhaust pipe connected to the tank and configured to exhaust a treated gas from which carbon dioxide has been removed by the carbon dioxide absorbent to the outside of the tank; A carbon dioxide absorption facility equipped with

6. A supplying step of supplying the carbon dioxide absorbent according to any one of claims 1 to 4 into an inside of a tank; a contacting step of contacting exhaust gas containing carbon dioxide with the carbon dioxide absorbent supplied inside the tank; a removing step of removing the carbon dioxide absorbent that has come into contact with the exhaust gas from the tank; A method for absorbing carbon dioxide comprising the steps of:

7. A power generation process in which biomass is combusted in a biomass-fired power plant to generate power; A production step of producing the carbon dioxide absorbent from biomass combustion ash discharged at the biomass thermal power plant, In the supplying step, the carbon dioxide absorbent produced in the producing step is supplied to the inside of the tank. The carbon dioxide absorption method according to claim 6.

8. Combusting the biomass; A step of generating a granular body including biomass combustion ash containing calcium oxide discharged by combustion of the biomass and a binder, the biomass combustion ash being aggregated by the binder; Including, The binder comprises calcium sulfate. A method for producing a carbon dioxide absorbent.

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