JP3110717B2 - How to fix carbon dioxide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an oxide of an alkali metal, an oxide of an alkaline earth metal, and an oxide of a heavy metal contained in combustion ash such as coal, refuse, and biomass, and construction waste, and the like. Carbonates and immobilizes them as carbonates, utilizing the energy generated by the carbonation of carbon dioxide, which is an exothermic reaction, for power generation, etc., and effectively using the solidified body obtained by carbonation of carbon dioxide for civil engineering materials such as roadbed materials The present invention relates to a method for immobilizing carbon dioxide.

[0002]

2. Description of the Related Art Carbon dioxide is one of the substances causing global warming, and it is desired to reduce its emission into the atmosphere. As one of the measures, it is conceivable to fix carbon dioxide by some method. However, carbon dioxide is one of the most chemically stable compounds, and highly immobilized reagents (high energy content)
Materials are required. For example, quick lime or lime milk can be considered as the alkaline reagent, but these are produced by calcining limestone which consumes a large amount of energy, and have a contradiction that carbon dioxide is generated in the process. Also,
A hydrate treatment technology has been developed in which the recovered carbon dioxide is converted into a sherbet-like hydrate under high pressure and stored on the sea floor. Further, a method has been developed in which carbon dioxide in exhaust gas is converted to carbon monoxide, and then methanol is produced from carbon dioxide and carbon monoxide, thereby fixing carbon dioxide (for example, Japanese Patent Application Laid-Open No. 7-1364).
No. 62).

[0003]

The conventional method of immobilizing carbon dioxide consumes energy for immobilizing carbon dioxide, and therefore has a problem in its significance and effect. In the hydrate treatment, carbon dioxide is stored as a hydrate, and is less reliable in terms of stability and the like than in the case where it is immobilized as a solid such as carbonate.

The present invention has been made in view of the above points, and an object of the present invention is to use an oxide of an alkali metal, an oxide of an alkaline earth metal, or an oxide of a heavy metal to fix carbon dioxide. By using coal, refuse, combustion ash such as biomass and construction waste, etc., carbon dioxide can be carbonized and immobilized as a carbonate without using energy or with a small amount of energy consumption. It is to provide a method. Further, an object of the present invention is to provide an oxide of an alkali metal, an oxide of an alkaline earth metal, or an oxide of a heavy metal contained in coal, refuse, combustion ash such as biomass, construction waste material, or the like, which carbonates carbon dioxide. It is an object of the present invention to provide a method for immobilizing carbon dioxide, which can generate electric power or the like by using reaction heat generated in the carbon dioxide. It is a further object of the present invention to provide a method for immobilizing carbon dioxide, in which a stable solidified body obtained by carbonation of carbon dioxide can be effectively used for civil engineering materials such as roadbed materials.

[0005]

To achieve the above object, according to the Invention The method of immobilizing the carbon dioxide of the present invention boosts the carbon dioxide or carbon dioxide-containing gas combustion ash and metal oxides including metal oxides It is characterized in that carbon dioxide is carbonized and immobilized as a carbonate by being brought into contact with at least one of wastes containing substances (see FIG. 3). Also, the method of the present invention, the pressure of carbon dioxide or carbon dioxide-containing gas
At least in contact with any of the waste containing ash and metal oxides including metal oxides, with immobilizing carbon dioxide as carbonated carbonates, recovering reaction heat generated during the carbonation and ( Fig. 6
reference). Here, examples of the combustion ash containing a metal oxide include combustion ash such as coal, refuse, and biomass, and examples of the waste containing a metal oxide include construction waste material. The metal oxide is, specifically, an oxide of an alkali metal (such as Na ₂ O or K ₂ O), an oxide of an alkaline earth metal (such as CaO or MgO), or an oxide of a heavy metal.

In the above method of the present invention, the heat of reaction generated by carbonation of carbon dioxide can be recovered and used for power generation and the like. Further, in these methods of the present invention,
Carbon dioxide is brought to a supercritical pressure and brought into contact with at least one of combustion ash containing metal oxide and waste containing metal oxide to increase the reaction rate of carbonation of carbon dioxide (FIGS. 3 and 6). reference). The critical pressure of carbon dioxide is 7.3 MPa. Combustion ash containing metal oxides and waste containing metal oxides (combustion ash such as coal, garbage, biomass and construction waste) react with carbon dioxide to generate heat, and carbon dioxide is carbonated and solidified. It becomes a body, but its reaction speed is slow. Therefore, as described above, if the reaction rate is increased by increasing the pressure of carbon dioxide or making carbon dioxide a supercritical pressure, carbonation of carbon dioxide occurs quickly, and the exothermic reaction of carbonation causes The generated heat can be used for power generation and the like as described above, and carbon dioxide can be used as fuel.

[0007] In addition, the method of the present invention reduces the combustion temperature and lowers the reaction rate of the exothermic reaction when at least one of ash-containing fuel (eg, coal), refuse, and biomass is charged into a combustion furnace and burned. By accelerating, the generated carbon dioxide reacts with the metal oxide in the combustion ash to be carbonated and fixed as carbonate,
It is characterized in that the reaction heat generated by carbonation of carbon dioxide is recovered and used effectively together with the heat of combustion (see FIG. 9). In addition, it is also possible to perform carbonation of carbon dioxide using combustion ash from another combustion furnace. In the method of the present invention, the reaction heat generated by carbonation of carbon dioxide can be recovered together with the heat of combustion and used for power generation and the like (see FIG. 9).

In the method of the present invention, a fuel (for example, coal) containing ash, at least one of refuse and biomass is charged into a combustion furnace and burned, and sensible heat of the combustion exhaust gas is recovered. The combustion flue gas after recovery is introduced into the CO ₂ fixation reactor, and the combustion ash from the combustion furnace is introduced into the CO ₂ fixation reactor, and carbonation, which is an exothermic reaction, is reduced.
The combustion exhaust gas and the combustion ash are brought into contact in a CO ₂ fixation reactor whose temperature is controlled to be promoted , and the carbon dioxide in the combustion exhaust gas is carbonized by the metal oxide in the combustion ash and fixed as carbonate. (See FIG. 7). In addition, the method of the present invention is characterized in that a fuel containing ash (for example, coal), at least one of refuse and biomass is charged into a combustion furnace and burned, and sensible heat of the combustion exhaust gas is recovered by heat recovery. The flue gas is introduced into the CO ₂ fixation reactor, and the combustion ash from the combustion furnace is removed from the CO ₂
Introduced into an immobilized reactor to promote exothermic carbonation
The combustion exhaust gas and the combustion ash are brought into contact in a CO ₂ immobilization reactor whose temperature is controlled so that the carbon dioxide in the combustion exhaust gas is carbonized by the metal oxide in the combustion ash and fixed as carbonate. In addition, it is characterized in that the reaction heat generated during carbonation is recovered and the recovered heat is used for power generation and the like (see FIG. 8). In this case, it is also possible to adopt a configuration in which the combustion exhaust gas and the combustion ash from different combustion furnaces are introduced into the CO ₂ fixed reactor.

Most of ash-containing fuel (for example, coal) and refuse are burned at 800 ° C. or higher, so that carbon, which is a main component of coal and refuse, is not sufficiently oxidized and oxidized only to CO _2. . Therefore, by lowering the temperature of the combustion furnace as shown in FIG. 9 or controlling the temperature of the CO ₂ immobilization reactor as shown in FIGS. 7 and 8, so as to be oxidized to CO ₃ , The chemical energy generated by carbonation, which is an exothermic reaction, is effectively used. This carbonation also reduces the CO ₂ concentration in the exhaust gas, and the carbon dioxide corresponding to the difference is fixed as a carbonate to form a stable solid. Carbonation of carbon dioxide is mainly performed by CaO (quick lime), but oxides of other alkali metals (Na
₂ O, K ₂ O, etc.), oxides of alkaline earth metals (MgO
Etc.) can also fix carbon dioxide as a carbonate. Further, in this carbonation, since the oxidation is performed in the vicinity of the equilibrium region, the free energy of formation is increased, and the exergy loss is reduced.

In the method of the present invention, a solidified product obtained by carbonating carbon dioxide and immobilizing it as a carbonate (for example,
It is desirable to use limestone (CaCO ₃ ) as a civil engineering material such as a roadbed material. A solidified body (for example, limestone) obtained by carbonating carbon dioxide is stable and can be effectively used as a roadbed material or the like as described above.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments such Nitsu <br/> stomach of the present invention will be described in detail. Figures 1 and 2 show the fixation of carbon dioxide
FIG. 3 shows an example of an apparatus for performing the carbonization method, and FIG. 3 shows a schematic configuration of an apparatus for performing the carbon dioxide immobilization method according to the first embodiment of the present invention. In the present embodiment and the like , carbon dioxide or a carbon dioxide-containing gas is brought into contact with combustion ash such as coal, refuse, biomass or the like and / or construction waste material to carbonize carbon dioxide and fix it as carbonate.
Coal, refuse, combustion ash such as biomass, construction waste, etc. are occupied by alkali metal oxides (Na ₂ O, K ₂ O, etc.), alkaline earth metal oxides (CaO, MgO, etc.), and heavy metal oxides. Carbon dioxide is carbonated by these alkali metal oxides, alkaline earth metal oxides, and heavy metal oxides, and is fixed as a carbonate. In addition, carbonation is mainly performed by CaO.

FIG. 1 shows a method of introducing a carbon dioxide-containing gas such as carbon dioxide or combustion exhaust gas into a CO ₂ -fixing reactor 10 and a combustion ash such as coal, refuse, and biomass.
And the construction waste material is introduced, and the carbon dioxide is oxidized to the carbonate by the oxide of the alkali metal, the oxide of the alkaline earth metal, and the oxide of the heavy metal in the combustion ash or / and the construction waste material to stably fix the carbon dioxide. Things. CO ₂ fixed reactor 1
As 0, a fluidized-bed reactor, a moving-bed reactor, a fixed-bed reactor, or the like is used, but is not limited thereto. FIG. 2 shows a fluidized bed type CO ₂ fixing reactor 10a.
In this example, the temperature in the CO ₂ immobilization reactor 10a is adjusted to control the carbonation of carbon dioxide, which is an exothermic reaction, to be promoted. In addition, 1
2 is a fluidized bed, 14 is a wind box, and 16 is a gas dispersion plate. Other configurations and operations are the same as those in FIG. FIG.
Fluidized bed type CO ₂ immobilization reactor 10b composed of a pressure vessel
In this case, the pressure of carbon dioxide in the pressure vessel 18 is increased or the pressure of the carbon dioxide is set to a supercritical pressure to increase the reaction rate of carbonation of carbon dioxide. 20 is a flange. Other configurations, operations, and the like are the same as those in FIGS.

FIGS. 4 and 5 show a method of immobilizing carbon dioxide.
FIG. 6 shows another example of an apparatus for performing the method , and FIG. 6 shows a schematic configuration of an apparatus for performing the method for immobilizing carbon dioxide according to the second embodiment of the present invention. In this embodiment and the like , carbon dioxide or a carbon dioxide-containing gas is brought into contact with coal, refuse, combustion ash such as biomass or / and construction waste material to carbonize carbon dioxide and immobilize it as a carbonate. It is intended to recover and effectively utilize the heat of reaction generated by a certain carbonation. As shown in FIG. 4, a heat transfer tube 22 for heat recovery is installed in the CO ₂ immobilization reactor 10 to recover heat generated by carbonation of carbon dioxide. As a heat medium of the heat transfer tube 22, for example, water, steam, or the like is used. Other configurations and operations are the same as those in FIG. Further, as shown in FIG. 5, CO ₂ fixing reactor 1
In the case where a heat transfer tube 22 for heat recovery is installed in the fluidized bed 12 of the reactor 0a or the heat transfer tube 22 for heat recovery is installed in the fluidized bed 12 of the CO ₂ fixed reactor 10b as shown in FIG. The same is true for The recovered heat can be used for power generation and the like as described later.

FIGS. 7 and 8 show a systematic schematic configuration of an apparatus for performing a method for immobilizing carbon dioxide according to a third embodiment of the present invention. In this embodiment, a fuel containing ash, such as coal, and refuse are burned at a high temperature in a combustion furnace (or an incinerator), and combustion exhaust gas containing carbon dioxide and combustion ash discharged from the combustion furnace are fixed to CO ₂ . It is introduced into a reactor for carbonation of carbon dioxide, and the heat of reaction accompanying the carbonation is recovered and used effectively. As shown in FIG.
Coal, garbage, etc. are put into the combustion furnace (or incinerator) 24,
The combustion is performed at a temperature of 800 ° C. or more (950 ° C. in FIG. 7). In this case, carbon, which is a main component of coal, refuse, and the like, is oxidized to CO ₂ , and combustion exhaust gas containing carbon dioxide is emitted. The combustion exhaust gas of 950 ° C. is recovered by the superheater 26 to 700 ° C., and the CO ₂ fixed reactor 2
8 is introduced. The combustion furnace 2 is installed in the CO ₂ fixing reactor 28.
4 is also introduced, wherein the carbon dioxide in the flue gas is converted into metal oxides (mainly CaO, but other alkali metal oxides, alkaline earth metal oxides, Heavy metal oxides can also participate.)
_It is oxidized, that is, carbonated, to ₃ to form a highly stable solidified body (for example, limestone (CaCO ₃ )). And
The CO ₂ concentration in the exhaust gas discharged from the CO ₂ fixing reactor 28 is reduced by the amount that the carbon dioxide in the combustion exhaust gas is fixed. The carbonation of carbon dioxide occurring in the CO ₂ fixation reactor 28 is an exothermic reaction, and the exhaust gas discharged from the CO ₂ fixation reactor 28 and ash containing carbonate (FIG. 7)
750 ° C.), heat is recovered by the evaporators 30 and 32, respectively, and is effectively used together with the heat recovered by the superheater 26.

For example, as shown in FIG.
Utilizing the heat recovered in the evaporators 30, 32,
If the steam turbine 34 is driven by the superheated steam from the superheater 26 and the power is generated by the generator 36, the carbon dioxide is fixed to reduce the emission amount of the carbon dioxide, and at the same time, the carbon dioxide is so-called. Electricity can be generated as fuel. 38 is a condenser. Furthermore, the solidified body (for example, limestone) obtained by carbonation of carbon dioxide is stable and can be effectively used as a civil engineering material such as a roadbed material. 8 is the same as that of FIG. 7 and 8, the CO ₂ immobilization reactor 28 is
Although a fluidized bed type reactor is used, it is also possible to use a moving bed type reactor, a fixed bed type reactor, etc., and also from a pressure vessel so that carbon dioxide can be pressurized or brought to a supercritical pressure. It is also possible to employ different reactors. Further, in the present embodiment, the configuration is such that the combustion exhaust gas and the combustion ash from one combustion furnace are introduced into the CO ₂ fixed reactor.
It is also possible to adopt a configuration in which combustion exhaust gas and combustion ash from separate combustion furnaces are introduced into a CO ₂ fixed reactor. Other points are the same as those in the first embodiment.

FIG. 9 shows a schematic configuration of an apparatus for performing a method for immobilizing carbon dioxide according to a fourth embodiment of the present invention. In this embodiment, when a fuel containing ash such as coal is burned in a fluidized bed combustion furnace, the reaction rate of carbonation of carbon dioxide is increased by lowering the temperature of the fluidized bed, the fixation of carbon dioxide, and the carbonation reaction The aim is to make effective use of the chemical energy obtained in the above. Note that the present embodiment is also applicable to incineration of garbage and the like. As shown in FIG. 9, coal or the like is charged into a fluidized bed combustion furnace 40 and is usually burned at 800 ° C. or higher. To burn down. 42 is a fluidized bed, 44 is a wind box, 4
6 is a gas dispersion plate, and 48 is a flue.

By lowering the temperature of the fluidized bed and burning, carbon dioxide, which is a major component of coal and the like, is oxidized to produce carbon dioxide. The metal oxides in the combustion ash (mainly CaO, but other alkalis) Metal oxides, alkaline earth metal oxides and heavy metal oxides can also be oxidized and carbonated (eg, limestone (CaCO ₃ ))
Immobilized as Then, the CO ₂ concentration in the combustion exhaust gas is reduced by the amount of the immobilized carbon dioxide. The wall surface of the fluidized bed combustion furnace 40 is a membrane wall 50 composed of an evaporating tube, and the reaction heat generated by carbonation of carbon dioxide is recovered together with the heat of combustion of coal or the like, and is stored as steam in the steam drum 52. The superheater 51 turns into superheated steam. The superheated steam drives the steam turbine 34 connected to the superheater 51, and the power generator 36 generates electric power. As described above, the amount of carbon dioxide emitted can be reduced by immobilizing carbon dioxide, and power can be generated using carbon dioxide as a fuel. In addition, it is also possible to throw combustion ash from another combustion furnace into the fluidized bed combustion furnace 40 and use it for carbonation of carbon dioxide.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. In the present embodiment, in the apparatus shown in FIG. 9, coal is put into a fluidized bed combustion furnace 40 and burned, and the superheated steam collected by the superheater 51 drives the steam turbine 34 to generate electricity by the generator 36. In this case, the power generation amount and the CO ₂ concentration in the combustion exhaust gas were examined. Most of fuel containing ash (coal in this embodiment), garbage, etc. is 800 ° C.
For combusting the above, is insufficient oxidation of carbon as its main component, only to CO ₂ is not oxidized. Therefore, as shown in FIG. 9, the fluidized bed temperature Tb is lowered so as to be oxidized to CO ₃ , and the chemical energy generated by carbonation, which is an exothermic reaction, is effectively used. FIG. 9 shows an example in which the fluidized bed temperature Tb is set to 750 ° C., and as a comparative example, as shown in FIG.
C. The configuration of FIG. 10 is the same as that of FIG.

Carbonation of carbon dioxide is mainly caused by carbon dioxide in the combustion ash.
Since it is performed by aO (quick lime), in this embodiment,
Let us mainly consider carbonation of carbon dioxide by CaO. It is to be noted that carbon dioxide can be immobilized as a carbonate also by other alkali metal oxides (Na ₂ O, K ₂ O, etc.) or alkaline earth metal oxides (MgO, etc.) contained in the combustion ash. Is possible. In the apparatus shown in FIGS. 9 and 10, when the input amount of coal is 10 Ton / hour and the emission amount of the combustion exhaust gas is 70,000 Nm ³ / hour, an output of 20,000 KW is obtained by burning the coal. That is, when the fluidized bed temperature Tb is 850 ° C. as shown in FIG. 10, an output of 20,000 kW is obtained, and the CO ₂ concentration in the combustion exhaust gas becomes 12.0%.

On the other hand, 15 wt% of combustion ash is generated from the input coal, and the amount of CaO contained in the combustion ash is as much as 4.5 wt% of the input coal. Therefore, when the fluidized bed temperature Tb is set to 750 ° C. as shown in FIG.
The reaction of O + CO ₂ → CaCO ₃ (reverse reaction of limestone firing, equilibrium at 780 ° C.) is promoted, and carbon dioxide is fixed as carbonate, and the heat generated by this reaction is effectively used for power generation You can do it. In the above reaction,
Since 750 kcal of energy is obtained per kg of CaO, if the fluidized bed temperature Tb is 750 ° C.,
An output of 0 kW was obtained, and the CO ₂ concentration in the combustion exhaust gas was 9.3 because of the fixed carbon dioxide.
%. Further, the limestone obtained by the immobilization is a stable solidified body, and can be effectively used as a roadbed material or the like. In addition, in the above reaction, since the oxidation occurs near the equilibrium region, the free energy of formation increases, and the exergy loss decreases.

[0021]

As described above, the present invention has the following effects. (1) Coal, garbage, biomass and other combustion ash and construction waste, etc., containing alkali metal oxides, alkaline earth metal oxides, and heavy metal oxides are used to fix carbon dioxide. The carbon dioxide can be carbonized and immobilized as a carbonate without using or using a small amount of energy. (2) Chemical energy obtained by carbonation of carbon dioxide can be utilized for power generation or the like, with little or no energy used for immobilizing carbon dioxide. (3) The solidified body (for example, limestone) obtained by carbonation of carbon dioxide can be effectively used for civil engineering materials such as roadbed materials. (4) Not only can carbon dioxide be fixed to contribute to the prevention of global warming, but also power generation can be performed using carbon dioxide as a fuel, and stable solidification of waste such as combustion ash and construction waste. It can be effectively used as a roadbed material as a body.

[Brief description of the drawings]

1 is a configuration diagram showing the concept of an apparatus for carrying out the method for immobilizing carbon dioxide.

2 is a schematic diagram showing an example of an apparatus for implementing the method for immobilizing carbon dioxide.

Figure 3 is a schematic diagram illustrating a fixing method equipment for implementing the carbon dioxide according to the first embodiment of the present invention.

4 is a configuration diagram showing the concept of an apparatus for carrying out the method for immobilizing carbon dioxide.

5 is a schematic diagram showing another <br/> example of an apparatus for implementing the method for immobilizing carbon dioxide.

6 is a schematic diagram illustrating a fixing method equipment for implementing the carbon dioxide according to the second embodiment of the present invention.

FIG. 7 is a systematic schematic configuration diagram showing an example of an apparatus for performing a method for immobilizing carbon dioxide according to a third embodiment of the present invention.

FIG. 8 is a systematic schematic configuration diagram showing another example of an apparatus for performing the method for immobilizing carbon dioxide according to the third embodiment of the present invention.

FIG. 9 is a schematic configuration diagram showing an apparatus for performing a method for immobilizing carbon dioxide according to a fourth embodiment of the present invention.

10 is a schematic configuration diagram in the case of performing combustion at a high temperature in the apparatus shown in FIG.

[Explanation of symbols]

10, 10a, 10b, 28 CO ₂ fixed reactor 12, 42 Fluidized bed 14, 44 Air box 16, 46 Gas dispersion plate 18 Pressure vessel 20 Flange 22 Heat transfer tube 24 Combustion furnace (incinerator) 26 Superheater 30, 32 Evaporator 34 Steam turbine 36 Generator 38 Condenser 40 Fluidized bed combustion furnace 48 Flue 50 Membrane wall 51 Superheater 52 Steam drum

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B01D 53/34 B01D 53/62 B01J 19/00 F23J 15/00

Claims (9)

(57) [Claims] 1. A carbon dioxide or carbon dioxide-containing gas temperature
A method for immobilizing carbon dioxide, comprising: pressurizing and contacting at least one of combustion ash containing metal oxide and waste containing metal oxide to carbonize carbon dioxide and immobilize it as carbonate. 2. Carbon dioxide or gas containing carbon dioxide is raised.
And pressurized to contact with at least one of combustion ash containing metal oxides and waste containing metal oxides, thereby carbonating carbon dioxide and fixing it as carbonate, and recovering reaction heat generated during carbonation. A method for immobilizing carbon dioxide. 3. The method for immobilizing carbon dioxide according to claim 2, wherein heat of reaction generated by carbonation of carbon dioxide is recovered and used for power generation . Wherein at least one the claims 1, 2 or 3 method for immobilizing carbon dioxide according contacting of waste carbon dioxide in the supercritical pressure containing combustion ash and metal oxide comprises a metal oxide. 5. The method according to claim 5, wherein at least one of ash-containing fuel, refuse, and biomass is charged into a combustion furnace and burned, by lowering a combustion temperature to increase a reaction rate of an exothermic reaction, thereby producing carbon dioxide. It is characterized by reacting with the metal oxides in it to be carbonated and fixed as carbonate, and also effectively recovering and effectively utilizing the reaction heat generated by carbonation of carbon dioxide together with the heat of combustion. How to fix carbon dioxide. 6. The method for immobilizing carbon dioxide according to claim 5 , wherein the reaction heat generated by carbonation of carbon dioxide is recovered together with the heat of combustion and used for power generation. 7. A fuel containing ash, at least one of refuse and biomass is charged into a combustion furnace and burned, and sensible heat of the combustion exhaust gas is recovered by heat. Then, the combustion exhaust gas after the heat recovery is subjected to CO ₂ fixation reaction. The combustion ash from the combustion furnace is introduced into this CO ₂ fixation reactor,
CO ₂ whose temperature is controlled to promote certain carbonation
The combustion exhaust gas and the combustion ash are brought into contact in the fixed reactor,
A method for immobilizing carbon dioxide, wherein carbon dioxide in combustion exhaust gas is carbonized by a metal oxide in combustion ash and immobilized as a carbonate. 8. A fuel containing ash, dust and biomass at least one is combusted by introducing into the combustion furnace, after the sensible heat of the combustion exhaust gas and heat recovery, the combustion exhaust gas after heat recovery CO ₂ immobilization reaction The combustion ash from the combustion furnace is introduced into this CO ₂ fixation reactor,
CO ₂ whose temperature is controlled to promote certain carbonation
The combustion exhaust gas and the combustion ash are brought into contact in the fixed reactor,
Carbon dioxide in the combustion exhaust gas is carbonized by metal oxide in the combustion ash and fixed as carbonate, and the heat of reaction generated during carbonation is recovered and the recovered heat is used for power generation. To fix carbon dioxide. 9. A method for immobilizing carbon dioxide according to any one of claims 1 to 8 for use of carbon dioxide solidified body immobilized as carbonated carbonates as construction materials.