Transport system for carbon dioxide from exhaust gas

Abstract

Provided is a transport system for carbon dioxide from exhaust gas, wherein the system does not require a special transport means or containers such as tanks having low-temperature resistance and high-pressure resistance, even in a place in which a carbon dioxide (CO2) recovery location and a CO2 storage location and a utilization location are separated locations, and has excellent handling and high transport energy efficiency without causing crushing, collapse, etc. since a solidified body obtained by solidifying CO2 in a form to be transported is provided with constant strength even when vibration or the like is applied by transport means such as a ship and a vehicle.　A transport system for carbon dioxide from exhaust gas, according to the present invention includes: (a) a step for obtaining a slurry containing magnesium carbonate from exhaust gas containing CO2; (b) a step for solidifying the slurry containing the carbonate; (c) a step for transporting the solidified magnesium carbonate from a first location to a second location; and (d) a step for decomposing the solidified magnesium carbonate into magnesium oxide and CO2 after transport.

Description

Carbon dioxide transport system from flue gases

[0001] The present invention relates to a transport system for carbon dioxide from exhaust gas, and in particular to a transport system for carbon dioxide from exhaust gas that uses a magnesium compound to solidify carbon dioxide in exhaust gas emitted from manufacturing facilities such as cement factories, thermal power plants, and chemical plants, and from transportation means such as ships, to prepare a solidified body with good strength, thereby improving the transportability of the solidified body and achieving excellent energy efficiency in transportation.

[0002] One of the causes of global warming is the greenhouse effect caused by carbon dioxide contained in combustion exhaust gases emitted from large-scale exhaust gas emission sources such as cement factories, thermal power plants, and chemical plants, and various efforts have been made to reduce the emission of such greenhouse gases. For example, a method has been proposed in which carbon dioxide is separated and captured from such combustion exhaust gases, and then stored underground without being released into the atmosphere. In addition, a method has been proposed in which water is electrolyzed using a photocatalyst, and H is isolated using a separation membrane. ２ Research into artificial photosynthesis, such as the synthesis of olefins and the production of plastic products using gas and recovered carbon dioxide with a catalyst that promotes chemical synthesis, and CO ２ Research into livestock energy using this has also begun.

[0003] One way to reduce carbon dioxide emissions into the atmosphere is to store it underground. Methods for storing carbon dioxide underground include carbon dioxide capture and storage (CCS), which captures carbon dioxide from exhaust gas and stores it underground, and enhanced oil recovery (EOR), which captures carbon dioxide from large-scale emission sources and injects and stores it in deep underground saline layers, depleted oil and gas fields, or oil fields with declining production efficiency, thereby reducing the rise in atmospheric carbon dioxide. Known carbon dioxide capture or removal technologies include chemical absorption, physical absorption, membrane separation, and adsorption, all of which use absorbent solutions. A typical capture technology is chemical absorption, which uses an amine aqueous solution.

[0004] The following technology has been proposed as a carbon dioxide capture technology for storing carbon dioxide underground. JP 2012-110805 A (Patent Document 1) discloses a carbon dioxide capture method for reducing operating costs by reducing the energy required to regenerate a carbon dioxide absorption solution, and specifically describes a carbon dioxide capture method including an absorption step of contacting a carbon dioxide-containing gas with an absorption solution to cause the absorption solution to absorb the carbon dioxide, a regeneration step of heating the absorption solution that has absorbed carbon dioxide in the absorption step to release the carbon dioxide from the absorption solution and regenerate the absorption solution, a depressurization step of reducing the pressure of the absorption solution regenerated in the regeneration step to a pressure lower than that in the regeneration step to generate water vapor from the absorption solution, and a pressurization step of pressurizing the water vapor generated in the depressurization step to a pressure equivalent to that in the regeneration tower step and supplying the water vapor to the regeneration step.

[0005] Furthermore, Japanese Patent Laid-Open Publication No. 2024-030963 (Patent Document 2) discloses a method for underground storage of carbon dioxide that can reliably contain carbon dioxide injected downward by ensuring the strength of a carbon dioxide shielding layer, and can efficiently store large amounts of carbon dioxide. Specifically, this method stores carbon dioxide alone or a liquefied mixed gas containing carbon dioxide as a main component in a geological layer under the seabed consisting of deposits on an acoustic base or in a geological layer on land, and includes a carbon dioxide sealing region that exists from the seabed or the ground to a predetermined depth and is made up of a geological layer that satisfies pressure and temperature conditions that allow carbon dioxide hydrate to be generated. The present invention describes a method for underground storage of carbon dioxide, which comprises injecting the carbon dioxide below a certain area to form a carbon dioxide reservoir, causing at least a portion of the carbon dioxide injected into the carbon dioxide reservoir to rise naturally toward the carbon dioxide sealed area due to the buoyancy of the carbon dioxide, thereby generating carbon dioxide hydrate, thereby forming a carbon dioxide shielding layer in the carbon dioxide sealed area, and when the carbon dioxide is injected into the stratum under the seabed or the stratum on land, increasing the pore pressure in the carbon dioxide sealed area by artificial water sealing in which at least one of seawater and water is injected into the carbon dioxide sealed area as pore water.

[0006] Furthermore, Japanese Patent Laid-Open Publication No. 2023-140554 (Patent Document 3) discloses a method for storing carbon dioxide in the soil, which comprises mixing at least one of the soil before improvement, an admixture to be mixed with the soil to be improved, or the soil after improvement with a gas having a higher volumetric ratio of carbon dioxide than the air at the construction site, or a carbonated solution in which carbon dioxide has been dissolved, and mixing the carbon dioxide into the mixture, thereby storing the carbon dioxide in the improved soil.

[0007] However, these underground storage methods are difficult to implement when the location where the carbon dioxide is collected and the location where the carbon dioxide is stored are far apart. In addition, carbon dioxide liquefied under low temperature and high pressure must be filled into a low temperature and high pressure resistant transport container and transported to the carbon dioxide storage location by transport means such as a ship or vehicle. This requires maintaining a low temperature during transport and high pressure operations, which imposes a heavy burden on transporting liquid carbon dioxide and results in extremely poor energy efficiency for transportation.

[0008] Another method for reducing atmospheric carbon dioxide is disclosed in Japanese Patent Laid-Open No. 2002-349793 (Patent Document 4), which discloses a method of injecting liquefied carbon dioxide into the sea. Specifically, this method is a method of injecting carbon dioxide into the sea, which comprises: a liquefied carbon dioxide storage tank into which liquefied carbon dioxide is supplied and into which the temperature inside the tank is maintained at a predetermined storage temperature; a discharge pump that discharges liquefied carbon dioxide from the storage tank; and nitrogen gas supply means that supplies nitrogen gas to the storage tank at the same pressure as a predetermined storage pressure of the storage tank so as to maintain the predetermined storage pressure of the storage tank, wherein the nitrogen gas supply means sets the storage pressure higher than the saturation pressure corresponding to the storage temperature inside the storage tank and is set to have a nitrogen gas supply capacity at the same storage pressure as or greater than the predetermined discharge capacity of the discharge pump.

[0009] Furthermore, as a method for transporting recovered carbon dioxide, for example, Japanese Patent Laid-Open No. 2024-076432 (Patent Document 5) discloses a carbon dioxide transport method comprising: a first transfer step of transporting liquid carbon dioxide recovered in equipment for recovering carbon dioxide contained in exhaust gas discharged from a combustion device from the equipment to a first tank installed in a remote location; and a second transfer step of transporting the liquid carbon dioxide from the first tank to the second tank via a first pipeline connecting the first tank to a second tank installed in a remote location from the first tank, wherein the first transfer step includes a transport vehicle transport step of storing the liquid carbon dioxide in a storage tank mounted on a transport vehicle and transporting the liquid carbon dioxide stored in the storage tank to the first tank by the transport vehicle.

[0010] However, all of the above methods involve transporting liquefied carbon dioxide, and during transportation, it is necessary to prevent the liquefied carbon dioxide from evaporating or becoming dry ice due to supercooling. Furthermore, when holding and transporting or conveying liquefied carbon dioxide, it is necessary to maintain a specified temperature and pressure, which poses the problem of requiring special tanks and transportation equipment, as well as energy to maintain the specified temperature and pressure.

[0011] JP 2012-110805 A JP 2024-030963 A JP 2023-140554 A JP 2002-349793 A JP 2024-076432 A

[0012] The object of the present invention is to solve the above problems and to ２ ) Collection locations and CO ２ Even if the storage and utilization locations are far away, no special transport means, such as low-temperature-resistant or high-pressure-resistant tanks, are required. Even if vibrations are applied by ships, vehicles, or other transport means, CO2 can be transported in a stable manner. ２The present invention aims to provide a transport system for carbon dioxide from exhaust gas, which produces a solidified body having good strength and excellent transport energy efficiency. Preferably, the present invention aims to provide a transport system for carbon dioxide from exhaust gas, which can be used to construct a circulation system that utilizes exhaust gas containing carbon dioxide emitted from factories, etc.

[0013] In order to solve the above problems, the present invention has found that the problems can be solved by preparing a slurry containing magnesium carbonate that fixes carbon dioxide, mixing the slurry with magnesium oxide and / or magnesium oxychloride cement (MOC) and / or magnesium oxysulfate cement (MOS), or other magnesium compounds that dissolve and reprecipitate in water and / or magnesium compounds that undergo a phase transition in water, and solidifying the mixture. This led to the development of the present invention, which has the following technical features:

[0014] (I) The carbon dioxide transport system of the present invention from exhaust gas comprises the following steps: ２ (b) solidifying the slurry containing the carbonate; (c) transporting the solidified magnesium carbonate from a first location to a second location; and (d) separating the solidified magnesium carbonate after transportation into magnesium oxide and CO. ２ and a step of decomposing the carbon dioxide from exhaust gas into the carbon dioxide.

[0015] (II) Preferably, in the system for transporting carbon dioxide from exhaust gas of the present invention, the step (b) comprises mixing magnesium oxide and / or magnesium oxychloride cement (MOC) and / or magnesium oxysulfate cement (MOS) with the slurry containing magnesium carbonate obtained in the step (a) and solidifying the mixture.

[0016] (III) More preferably, in the system for transporting carbon dioxide from exhaust gas of the present invention, the step (a) comprises the steps of: (a1) transporting CO ２(a1) a step of obtaining a carbonate of an alkali other than an alkaline earth metal from exhaust gas containing the above-mentioned carbon dioxide, and (a2) a step of reacting the carbonate of the alkali obtained in the step (a1) with a hydroxide of magnesium to obtain the carbonate of magnesium.

[0017] (IV) Preferably, in any of the above systems for transporting carbon dioxide from exhaust gas of the present invention, the system further comprises: (p) after step (d), a step of reacting the magnesium oxide obtained in step (d) with water to obtain magnesium hydroxide; (q) a step of transporting the magnesium hydroxide obtained in step (p) to a first location; and (r) a step of recycling and reusing the magnesium hydroxide after transportation as the magnesium hydroxide in step (a).

[0018] (V) Preferably, in any of the above systems for transporting carbon dioxide from exhaust gas of the present invention, the system further comprises: (f) a step of transporting the magnesium oxide obtained in step (d) to a first location; (g) a step of reacting the transported magnesium oxide with water to obtain magnesium hydroxide; and (h) a step of recycling and reusing the magnesium hydroxide obtained in step (g) as the magnesium hydroxide in step (a).

[0019] (VI) More preferably, in the system for transporting carbon dioxide from exhaust gas of the present invention, the reaction heat generated when the magnesium oxide is reacted with water to obtain magnesium hydroxide in the step (g) is used for solidification in the step (b).

[0020] (VII) More preferably, in the system for transporting carbon dioxide from exhaust gas of the present invention, the exhaust gas is an exhaust gas generated from a transport means during transportation.

[0021] (VIII) More preferably, in the system for transporting carbon dioxide from exhaust gas of the present invention, (e) the CO obtained by the decomposition in the step (d) is ２ and injecting the carbon dioxide from the exhaust gas into the ground.

[0022] In the present invention, "solidification" refers to the process of blending magnesium oxide and / or magnesium oxychloride cement (MOC) and / or magnesium oxysulfate cement (MOS), or other magnesium compounds that dissolve and reprecipitate in water and / or magnesium compounds that undergo a phase transition in water, with a magnesium-containing carbonate slurry, and solidifying the carbonate slurry containing the magnesium compounds as a result of the blended magnesium compounds having a solidifying function. Furthermore, "transport" is intended to include the concepts of transfer and transportation.

[0023] According to the present invention, since the present invention contains magnesium compounds such as magnesium oxide and / or magnesium oxychloride cement (MOC) and / or magnesium oxysulfate cement (MOS), the solidification of the compounds reduces CO2 contained in the exhaust gas. ２ The carbonate slurry with carbon dioxide fixed therein is firmly solidified, making it easy to store. Furthermore, the solidified body has the strength to maintain its solid state even when subjected to vibrations, etc., caused by transportation means such as ships, vehicles, and trains. ２ ) Collection locations and CO ２ Even if the location where the carbon dioxide is stored or utilized is far away, a special transport container for transporting the solidified body with immobilized carbon dioxide, such as a tank or the like that can withstand low temperatures or high pressures, is not required, and the transport stability is improved, and a transport system for carbon dioxide from exhaust gas with excellent transport energy efficiency can be achieved. Furthermore, according to the preferred embodiment of the present invention, it is possible to construct an effective circulation system that utilizes exhaust gas containing carbon dioxide emitted from factories, etc.

[0024] In addition, CO obtained by decomposition from the solidified carbon dioxide transported with energy efficiency by the transportation system of the present invention.２ It is possible to efficiently inject and store CO into deep underground saline layers, such as CSS and EOR, depleted oil and gas fields, producing oil fields with reduced production efficiency, and abandoned mines in shallow layers less than 800 meters underground. ２ as an industrial raw material, for example in the production of plastics, and as CO ２ CO2 to store energy ２ This makes it possible to use the material in known applications such as batteries, and makes it possible to suppress the increase in carbon dioxide in the atmosphere, which is an environmental problem.

[0025] Fig. 1 is a diagram schematically showing an example of the outline of the system for transporting carbon dioxide from exhaust gas according to the present invention. Fig. 2 is a diagram schematically showing another example of the outline of the system for transporting carbon dioxide from exhaust gas according to the present invention.

[0026] The present invention will be described by the following preferred examples, but is not limited thereto. The carbon dioxide transport system of the present invention from exhaust gas comprises: (a) a CO ２ (b) obtaining a slurry containing magnesium carbonate from an exhaust gas containing the carbonate; (c) transporting the solidified magnesium carbonate from a first location to a second location; and (d) separating the solidified magnesium carbonate after transportation into magnesium oxide and CO. ２ and a process for decomposing carbon dioxide from exhaust gas into carbon dioxide.

[0027] Preferably, the system for transporting carbon dioxide from exhaust gas further comprises, following step (d), the following steps: (p) reacting the magnesium oxide obtained in step (d) with water to obtain magnesium hydroxide; (q) transporting the magnesium hydroxide obtained in step (p) to a first location; and (r) recycling the transported magnesium hydroxide as the magnesium hydroxide in step (a). Alternatively, the system further comprises: (f) transporting the magnesium oxide obtained in step (d) to a first location; (g) reacting the transported magnesium oxide with water to obtain magnesium hydroxide; and (h) recycling the magnesium hydroxide obtained in step (g) as the magnesium hydroxide in step (a).

[0028] The carbon dioxide transport system from exhaust gas of the present invention will be described below with reference to the following preferred examples, but is not limited thereto. The following description will be given based on the examples shown in Figures 1 and 2. Step (a) of the carbon dioxide transport system from exhaust gas of the present invention is a step of extracting CO ２ This is a process for obtaining a slurry containing magnesium carbonate from exhaust gas containing CO (Fig. 1). ２ Examples of exhaust gases containing CO include exhaust gases generated from manufacturing facilities such as cement factories, and from transportation means such as ships and vehicles. ２ The exhaust gas may be any exhaust gas containing at least CO ２ The exhaust gas may contain other components such as sulfur oxides (SOx) and nitrogen oxides (NOx).

[0029] As shown in FIG. 1, in step (a), specifically, CO ２ and contacting an exhaust gas containing the compound with a magnesium hydroxide solution, thereby removing CO from the exhaust gas. ２This is a step of reacting the magnesium hydroxide with the exhaust gas to produce a slurry containing magnesium carbonate. The exhaust gas may be heated in advance to 60°C or higher in order to increase the efficiency of the reaction with the magnesium hydroxide. If necessary, the magnesium hydroxide obtained in the step (g) or the magnesium hydroxide in the step (r) described later may be used as the magnesium hydroxide, and CO ２ The magnesium hydroxide may be used as the magnesium hydroxide to be contacted with exhaust gas containing magnesium.

[0030] The concentration of the magnesium hydroxide solution is determined by the CO ２ The concentration can be determined appropriately depending on the CO concentration in the exhaust gas. ２ Depending on the components contained other than those mentioned above, exhaust gas is brought into contact with magnesium hydroxide to produce a slurry containing magnesium carbonate, but there are also cases where a slurry containing magnesium sulfate, magnesium nitrate, etc. is produced. For example, when sulfur oxide is contained in the exhaust gas, a slurry containing magnesium sulfate, which is a reaction product of magnesium hydroxide and sulfur oxide, may be produced, and when nitrogen oxide is contained in the exhaust gas, a slurry containing magnesium nitrate, which is a reaction product of magnesium hydroxide and nitrogen oxide, may be produced.

[0031] Of the components contained in the exhaust gas, those that have low reactivity with magnesium hydroxide are preferably removed by being discharged from the system in the step of contacting the exhaust gas with magnesium hydroxide.

[0032] When the slurry containing magnesium carbonate also contains magnesium sulfate or magnesium nitrate, it is desirable to separate the magnesium carbonate from the magnesium sulfate or magnesium nitrate from the viewpoint of looping and circulating the magnesium. However, when the amount of sulfur oxides and nitrogen oxides contained in the exhaust gas is small, the magnesium sulfate or magnesium nitrate produced does not need to be separated.

[0033] A method for separating magnesium carbonate from components other than magnesium carbonate, such as magnesium sulfate and magnesium nitrate, can be, for example, a method in which the difference in solubility in water is utilized to adjust the solid-liquid ratio of the slurry to dissolve the component in the water of the slurry, and then a solid-liquid separation means such as a filter press is combined. Such a separation method may involve applying a plurality of known separation methods or a plurality of separation devices. The separated components other than magnesium carbonate are discharged as a solution and removed from the system. The removed sulfates and nitrates other than magnesium carbonate can be separated into magnesium hydroxide, sulfuric acid, and nitric acid, for example, by electrodialysis using a bipolar membrane.

[0034] As shown in FIG. 2, the step (a) preferably includes the following steps (a1) and (a2), and suitable steps (a1) and (a2) can be exemplified as follows: Step (a1) Step (a1) is a step in which CO ２ This is a process for preparing a solution and / or slurry containing a carbonate of an alkali other than an alkaline earth metal from exhaust gas containing CO ２ and contacting the exhaust gas containing the compound with an alkaline solution other than alkaline earth metals, thereby removing CO ２ In this process, the exhaust gas is absorbed into the alkaline solution to produce a solution and / or slurry containing an alkali carbonate. The exhaust gas may be preheated to 60°C or higher to increase the absorption efficiency of the alkaline solution. Hereinafter, the alkaline solution refers to an alkaline solution containing an alkali other than an alkaline earth metal.

[0035] CO in exhaust gas ２ The alkaline solution for absorbing CO ２ The alkaline solution is not particularly limited as long as it can absorb the above-mentioned components, and any alkaline solution can be used. Examples of the alkaline solution include an aqueous solution containing a hydroxide of an alkali metal (potassium, sodium, etc.), an aqueous solution containing ammonia, and an amine.

[0036] The concentration of the alkaline solution depends on the type of alkali contained, the amount of CO in the exhaust gas, and ２ For example, the amount of CO in the exhaust gas can be determined appropriately depending on the concentration of CO ２ When the concentration is 7 to 10% by mass and the alkaline solution is a sodium hydroxide solution, the concentration of the sodium hydroxide solution can be 1 to 20% by mass.

[0037] CO ２ When exhaust gas containing the above-mentioned alkali metal carbonates and / or hydrogen carbonates of the alkali metals (such as alkali metals, ammonia, and amines) is brought into contact with the alkaline solution, a solution and / or slurry containing carbonates and / or hydrogen carbonates of the alkali metals (hereinafter referred to as "slurries containing carbonates of alkali metals") is produced. For example, when the alkaline solution is a hydroxide of an alkali metal, a slurry containing carbonates of alkali metals is produced.

[0038] In addition, CO in the exhaust gas ２ Depending on the components contained other than those mentioned above, contacting exhaust gas with an alkaline solution may produce a solution and / or slurry containing, in addition to the alkali carbonate and / or bicarbonate contained in the alkaline solution, alkali sulfate, alkali nitrate, etc. For example, when the alkaline solution is an aqueous solution containing an alkali metal hydroxide, in addition to the alkali metal carbonate and / or bicarbonate, if sulfur oxide is contained in the exhaust gas, a solution and / or slurry containing alkali metal sulfate, which is a reaction product between the alkali metal hydroxide and sulfur oxide, may be produced, or if nitrogen oxide is contained in the exhaust gas, a solution and / or slurry containing alkali metal nitrate, which is a reaction product between the alkali metal hydroxide and nitrogen oxide may be produced. For example, if the alkali metal is sodium or potassium, a solution and / or slurry containing sodium sulfate or potassium sulfate, sodium nitrate or potassium nitrate, in addition to sodium carbonate or potassium carbonate, may be produced.

[0039] Of the components contained in the exhaust gas, those that are less reactive with the alkaline solution are preferably removed by being discharged from the system in the step of contacting the exhaust gas with the alkaline solution.

[0040] Step (a2) Step (a2) is a step of reacting the slurry containing alkali metal carbonates produced in step (a1) with magnesium hydroxide to produce magnesium carbonate, thereby preparing a slurry containing magnesium carbonate. When the alkali carbonate is an alkali metal carbonate, magnesium hydroxide is added to the slurry containing alkali metal carbonates and reacted to prepare a slurry containing magnesium carbonate.

[0041] When the slurry containing alkali metal carbonates produced in the above step (a1) contains alkali sulfates or nitrates, magnesium sulfate or magnesium nitrate is produced in the slurry by contact with magnesium hydroxide. When magnesium sulfate or magnesium nitrate is contained in the slurry containing magnesium carbonates prepared in the step (a2), it is desirable to separate the magnesium carbonate from the magnesium sulfate or magnesium nitrate from the viewpoint of looping and circulating the magnesium. However, when the amount of sulfur oxides and nitrogen oxides contained in the exhaust gas is small, the produced magnesium sulfate or magnesium nitrate does not need to be separated.

[0042] As a method for separating magnesium carbonate from components other than magnesium carbonate, such as magnesium sulfate and magnesium nitrate, a separation method utilizing the difference in solubility in water can be used, as described above. Such a separation method may involve applying a plurality of known separation methods or may involve using a plurality of separation devices. The separated components other than magnesium carbonate are discharged as a solution to the outside of the system and removed.

[0043] The removed sulfates and nitrates other than magnesium carbonate can be separated into magnesium hydroxide, sulfuric acid, and nitric acid by, for example, electrodialysis using a bipolar membrane.

[0044] Step (b) Step (b) in the system for transporting carbon dioxide from exhaust gas of the present invention is a step of solidifying the slurry containing magnesium carbonate obtained in step (a). As described above, "solidification" refers to the process of blending a magnesium compound that dissolves and reprecipitates in water and / or a magnesium compound that undergoes a phase transition in water, such as magnesium oxide and / or magnesium oxychloride cement (MOC) and / or magnesium oxysulfate cement (MOS), with a magnesium-containing carbonate slurry, and solidifying the carbonate slurry containing the magnesium compound as a result of the blended magnesium compounds, such as magnesium oxide and / or magnesium oxychloride cement (MOC) and / or magnesium oxysulfate cement (MOS), exhibiting a solidifying function.

[0045] Specifically, the obtained slurry containing magnesium carbonate is mixed with magnesium compounds that dissolve and reprecipitate in water and / or magnesium compounds that undergo a phase transition in water, such as magnesium oxide and / or magnesium oxychloride cement (MOC) and / or magnesium oxysulfate cement (MOS). The mixed magnesium compounds, such as magnesium oxide and / or magnesium oxychloride cement (MOC) and / or magnesium oxysulfate cement (MOS), include magnesium hydroxide, 5Mg(OH), ２ + MgCl ２ ・8H ２ O, 5Mg(OH) ２ + MgSO ４ ・8H ２ When the solidification occurs after transformation into a phase such as O, the resulting solidified body can be strengthened by forming nuclei.

[0046] In this way, by blending magnesium oxide and / or magnesium oxychloride cement (MOC) and / or magnesium oxysulfate cement (MOS) or other magnesium compounds with a slurry containing magnesium carbonate and solidifying the magnesium carbonate, the strength of the solidified body produced can be increased, and when the solidified body is transported, even during transport involving vibration, it is possible to maintain the shape of the solidified body without crushing or scattering, making it easy to store and resulting in a solidified body that is easy to handle.

[0047] The solidification can be achieved by dissolving and reprecipitating the carbonate slurry containing the magnesium compound at, for example, 60 to 90°C, preferably 70 to 80°C, and / or by causing a phase transition in water. When the slurry is dried, if fine powder is present in the dried slurry, the fine powder may scatter during transportation. However, as in the present invention, the scattering of fine powder can be suppressed even if the solidified product contains moisture or if the moisture is removed by leaving it. As a heat source for solidification, a heat source from exhaust gas emitted from a factory or the like, or a heat source generated in step (g) described below, as necessary, can be suitably used, but the heat source is not limited to these heat sources.

[0048] Step (c) Step (c) in the system for transporting carbon dioxide from exhaust gas of the present invention is a step of transporting the solidified body containing magnesium carbonate obtained in step (b) from a first location to a second location. Examples of transportation means include vehicles such as trucks, ships, trains such as electric trains and locomotives, and belt conveyors, but are not limited to these as long as the solidified body can be transported.

[0049] Furthermore, unlike conventional methods, the solidified body containing magnesium carbonate can be transported at room temperature and pressure. ２ The second location may be a CO recovery site from the magnesium solidified body. ２ It may be a place where water is stored or used.

[0050] The first location may be any location, such as a location within the same country as the second location, a vessel or other means of transportation, or a location in a different country from the second location. Conversely, the second location may be any location, such as a location within the same country as the first location, a vessel or other means of transportation, or a location in a different country from the first location. In addition, the first location may be located closer to CO than the second location. ２ Whether it's a place with a lot of CO2, a region, a country, etc. ２ It may also be a region or country with low emissions.

[0051] Step (d) in the system for transporting carbon dioxide from exhaust gas of the present invention is to convert the solidified magnesium carbonate after transport to the second location via step (c) into magnesium oxide and CO ２ As a decomposition method, for example, thermal decomposition can be used. For example, by heating the solidified magnesium carbonate to the decomposition temperature of the carbonate, for example, 700 to 1000°C, the solidified magnesium carbonate is decomposed into magnesium oxide and CO ２ It can be decomposed into:

[0052] Step (e) In the system for transporting carbon dioxide from exhaust gas of the present invention, step (e) is a step that is preferably added to the system for transporting carbon dioxide from exhaust gas. The step (e) is a step of transporting carbon dioxide generated by decomposition of magnesium carbonate in step (d). ２ is a process in which CO is injected underground via a pipeline or the like for storage or utilization. Underground storage includes not only CCS and EOR, but also well-known underground storage methods such as abandoned mines in shallow layers less than 800 meters underground. ２ Any known method used in CCS, EOR, etc. can be applied as a method for injecting CO underground. ２ In order to increase the concentration of CO ２ Any known method for increasing the concentration of may be applied.

[0053] Steps (p), (q), and (r) Step (p), which is a further step that is preferably added to the system for transporting carbon dioxide from exhaust gas of the present invention, is a step of reacting magnesium oxide produced by decomposition in step (d) with water to produce magnesium hydroxide.

[0054] In the step (g) described later, it is possible to generate magnesium hydroxide at the first location and use the generated heat in the step (b) described above. For example, the present invention can be applied to CO2 emitted from ships during transportation. ２ When the present invention is applied to the recovery and fixation of magnesium oxide in a transportation means, it is preferable to generate magnesium hydroxide by reacting magnesium oxide with water as in step (p), which makes it possible to apply the present invention to transportation means such as ships.

[0055] Step (q) is a step of transporting the magnesium hydroxide obtained in step (p) to the first location. The magnesium hydroxide produced in step (p) can be transported from the second location to another location, for example, by a transport means, and transport is preferably from the second location to the first location. As above, examples of transport means include vehicles such as trucks, ships, trains, and locomotives, but are not limited to these as long as they are capable of transporting magnesium hydroxide. Furthermore, the magnesium hydroxide obtained in step (p) can be transported to, for example, the first location at room temperature and atmospheric pressure. Step (r) is a step of using the magnesium hydroxide transported to the first location in step q as a raw material (magnesium hydroxide) for the slurry containing magnesium carbonate in step (a). All or part of the magnesium hydroxide produced in step (r) can be used as the magnesium hydroxide in step (a).

[0056] The present invention is applied to CO emitted from ships and the like during transportation. ２When the present invention is applied to the recovery and fixation of magnesium oxide in a transportation means, it is desirable to generate magnesium hydroxide by reacting magnesium oxide with water in step (p) as described above, and this makes it possible to apply the present invention to transportation means such as ships.

[0057] Steps (f), (g), and (h): Instead of the steps (p) to (r) above, the following steps (f) to (h) can also be applied. Step (f) is a step of transporting the magnesium oxide obtained in step (d) above from a second location to a first location. As with the above, examples of transportation means include vehicles such as trucks, ships, trains, locomotives, and belt conveyers, but are not limited to these as long as they can transport magnesium oxide. Furthermore, the magnesium oxide can be transported at room temperature and atmospheric pressure. The magnesium oxide transported to the first location can also be used as a raw material for magnesium oxide, MOC, and MOS to be used in the subsequent step (g) and for solidification in step (b) above.

[0058] The step (g) is a step of reacting the magnesium oxide transported to the first location in the step (f) with water to produce magnesium hydroxide, similar to the step (p), and the step (h) is a step of reacting the obtained magnesium hydroxide with the CO ２ This is a process in which the magnesium hydroxide is recycled and reused to immobilize the magnesium.

[0059] The reaction between magnesium oxide and water in step (g) is an exothermic reaction, and the generated heat can be used in the solidification step in step (b). There is no particular limitation on whether all or a portion of the generated heat is used in step (b). Furthermore, before using the obtained magnesium hydroxide in step (a), it is desirable to separate unreacted magnesium oxide, water, etc., in order to increase the purity.

[0060] Thus, the carbon dioxide transport system of the present invention from exhaust gas is ２ a first location which is a collection location for CO ２Even if the storage location and the second location where the CO2 is to be used are far away, the solidified body of magnesium carbonate with immobilized CO2 has good strength, which improves ease of storage. Furthermore, when transported, the solidified body does not break down or crumble, but retains its shape, and can be transported to the second location at room temperature and pressure by means of transportation such as a ship or vehicle. This is different from conventional CO2 storage. ２ Compared to transporting carbon dioxide in liquid form, this method does not require special equipment such as storage tanks or the energy required to maintain a specified temperature and pressure, which improves transport stability and makes it possible to realize a carbon dioxide transport system with excellent energy efficiency.

[0061] The carbon dioxide transport system of the present invention is an energy-efficient system that reduces carbon dioxide emissions into the atmosphere and ２ Since it can be effectively fixed and transported with energy efficiency, it can be efficiently injected and stored underground in deep underground saline layers such as CSS and EOR, depleted oil and gas fields, producing oil fields with reduced production efficiency, and abandoned mines in shallow layers. ２ as an industrial raw material, for example in the production of plastics, and as CO ２ CO2 storage using energy ２ The material can be used in known applications such as batteries, and can be suitably applied to factories in coastal areas and inland areas that emit carbon dioxide.

Claims

1. (a) CO ２ (b) obtaining a slurry containing magnesium carbonate from an exhaust gas containing the carbonate; (c) transporting the solidified magnesium carbonate from a first location to a second location; and (d) separating the solidified magnesium carbonate after transportation into magnesium oxide and CO. ２ and a step of decomposing the carbon dioxide from exhaust gas into the carbon dioxide.

2. The carbon dioxide transport system from exhaust gas according to claim 1, wherein step (b) comprises mixing magnesium oxide and / or magnesium oxychloride cement (MOC) and / or magnesium oxysulfate cement (MOS) with the magnesium carbonate-containing slurry obtained in step (a) and solidifying the mixture.

3. The step (a) comprises: (a1) CO ２ 3. The carbon dioxide transport system according to claim 1, further comprising: (a1) a step of obtaining a carbonate of an alkali other than an alkaline earth metal from exhaust gas containing the above-mentioned compound; and (a2) a step of reacting the carbonate of the alkali obtained in the step (a1) with a hydroxide of magnesium to obtain the carbonate of magnesium.

4. A carbon dioxide transportation system from exhaust gas according to claim 1 or 2, further comprising: (p) a step after step (d), of reacting the magnesium oxide obtained in step (d) with water to obtain magnesium hydroxide; (q) a step of transporting the magnesium hydroxide obtained in step (p) to a first location; and (r) a step of recycling and reusing the magnesium hydroxide after transportation as the magnesium hydroxide in step (a).

5. A carbon dioxide transportation system from exhaust gas according to claim 1 or 2, further comprising: (f) a step of transporting the magnesium oxide obtained in step (d) to a first location; (g) a step of reacting the transported magnesium oxide with water to obtain magnesium hydroxide; and (h) a step of recycling the magnesium hydroxide obtained in step (g) as the magnesium hydroxide in step (a).

6. A carbon dioxide transport system from exhaust gas according to claim 5, wherein the reaction heat generated in step (g) when the magnesium oxide is reacted with water to obtain magnesium hydroxide is used for solidification in step (b).

7. A carbon dioxide transport system from exhaust gas according to claim 1 or 2, characterized in that the exhaust gas is exhaust gas generated from a means of transportation during transportation.

8. (e) CO obtained by decomposition in the above (d) step ２ 3. The carbon dioxide transport system from flue gas according to claim 1 or 2, further comprising the step of: injecting the carbon dioxide from the flue gas into the ground.

Images