System for transporting carbon dioxide from exhaust gas

Abstract

Provided is a system for transporting carbon dioxide from exhaust gas, said system not requiring a special transport means such as a tank or other container having resistance to low temperature and resistance to high pressure, even in a location where a carbon dioxide (CO2) recovery location is separated from a CO2 storage location or usage location, and having exceptional energy transport efficiency and exceptional handling without any occurrence of crushing, collapse, or the like because a solidified body in which the CO2 is solidified as a mode of transport is provided with constant strength, even when vibration or the like is applied thereto by a transport means such as a ship or a vehicle.　A system for transporting carbon dioxide from exhaust gas according to the present invention comprises the following steps: (a) a step for obtaining a slurry that contains a carbonate of calcium from exhaust gas that contains CO2; (b) a step for solidifying the slurry containing the carbonate; (c) a step for transporting the solidified carbonate of calcium from a first location to a second location; and (d) a step for decomposing the solidified carbonate of calcium, after transport, into an oxide of calcium and CO2.

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 calcium 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, and 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 calcium carbonate that fixes carbon dioxide, mixing the slurry with a calcium compound that dissolves and reprecipitates in water and / or a calcium compound that undergoes a phase transition in water, and solidifying the slurry, etc., and has 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) obtaining a slurry containing calcium carbonate from an exhaust gas containing the carbonate; (c) transporting the solidified calcium carbonate from a first location to a second location; and (d) separating the solidified calcium carbonate after transportation into calcium 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 amorphous calcium carbonate and / or basic calcium carbonate and / or vaterite with the slurry containing calcium carbonate obtained in the step (a) to solidify it.

[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(a2) reacting the alkali carbonate obtained in step (a1) with calcium hydroxide to obtain the calcium carbonate.

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

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

[0019] (VI) More preferably, in the system for transporting carbon dioxide from exhaust gas according to the present invention, the reaction heat generated when the calcium oxide is reacted with water to obtain calcium 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 transportation 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 adding amorphous calcium carbonate and / or basic calcium carbonate and / or a calcium compound that dissolves and reprecipitates in water, such as vaterite, and / or a calcium compound that undergoes a phase transition in water to a calcium-containing carbonate slurry, and solidifying the carbonate slurry containing the calcium compound by the added calcium compound having a solidifying function. Furthermore, "transportation" also includes the concepts of transfer and transportation.

[0023] According to the present invention, since the present invention contains calcium compounds such as amorphous calcium carbonate, basic calcium carbonate, and vaterite, the solidification of the compounds reduces the CO 2 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. ２It 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 with reference to the following preferred embodiments, but is not limited thereto. The carbon dioxide transport system of the present invention comprises: (a) a CO ２ (b) obtaining a slurry containing calcium carbonate from an exhaust gas containing the carbonate; (c) transporting the solidified calcium carbonate from a first location to a second location; and (d) separating the solidified calcium carbonate after transportation into calcium 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 calcium oxide obtained in step (d) with water to obtain calcium hydroxide; (q) transporting the calcium hydroxide obtained in step (p) to a first location; and (r) recycling the transported calcium hydroxide as the calcium hydroxide in step (a). Alternatively, the system further comprises: (f) transporting the calcium oxide obtained in step (d) to a first location; (g) reacting the transported calcium oxide with water to obtain calcium hydroxide; and (h) recycling the calcium hydroxide obtained in step (g) as the calcium 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 calcium 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 the exhaust gas containing the hydroxide of calcium with a solution of calcium hydroxide, ２This is a step of reacting the calcium hydroxide with the exhaust gas to produce a slurry containing calcium carbonate. The exhaust gas may be preheated to 60°C or higher in order to increase the efficiency of the reaction with the calcium hydroxide. If necessary, the calcium hydroxide obtained in step (g) or the calcium hydroxide in step (r) described later may be used as the calcium hydroxide, and CO ２ It may also be used as a calcium hydroxide to be contacted with exhaust gas containing calcium hydroxide.

[0030] The concentration of the calcium 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, the exhaust gas is brought into contact with calcium hydroxide to produce a slurry containing calcium carbonate, but there are also cases where a slurry containing calcium sulfate, calcium nitrate, etc. is produced. For example, when sulfur oxide is contained in the exhaust gas, a slurry containing calcium sulfate, which is a reaction product of calcium hydroxide and sulfur oxide, may be produced, and when nitrogen oxide is contained in the exhaust gas, a slurry containing calcium nitrate, which is a reaction product of calcium hydroxide and nitrogen oxide, may be produced.

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

[0032] When calcium carbonate-containing slurry also contains calcium sulfate or calcium nitrate, it is desirable to separate calcium carbonate from calcium sulfate or calcium nitrate from the viewpoint of looping and circulating calcium. However, when the exhaust gas contains only trace amounts of sulfur oxides and nitrogen oxides, the produced calcium sulfate or calcium nitrate does not need to be separated.

[0033] A method for separating calcium carbonate from components other than calcium carbonate, such as calcium sulfate and calcium nitrate, can be, for example, a method in which the solid-liquid ratio of the slurry is adjusted by utilizing the difference in solubility in water 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 be performed by applying a plurality of known separation methods or by using a plurality of separation devices. The separated components other than calcium carbonate are discharged as a solution and removed from the system. The removed sulfates and nitrates other than calcium carbonate can be separated into calcium 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 calcium hydroxide to produce calcium carbonate, thereby preparing a slurry containing calcium carbonate. When the alkali carbonate is an alkali metal carbonate, calcium hydroxide is added to the slurry containing alkali metal carbonates and reacted to prepare a slurry containing calcium carbonate.

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

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

[0043] The removed sulfates and nitrates other than calcium carbonate can be separated into calcium 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 calcium carbonate obtained in step (a). As described above, "solidification" refers to the process of blending a calcium-containing carbonate slurry with a calcium compound that dissolves and reprecipitates in water and / or a calcium compound that undergoes a phase transition in water, such as amorphous calcium carbonate, basic calcium carbonate, or vaterite, and solidifying the carbonate slurry containing the calcium compound by allowing the blended calcium compound, such as amorphous calcium carbonate, basic calcium carbonate, or vaterite, to exhibit a solidifying function.

[0045] Specifically, the resulting slurry containing calcium carbonate is mixed with a calcium compound that dissolves and reprecipitates in water and / or a calcium compound that undergoes a phase transition in water, such as amorphous calcium carbonate, basic calcium carbonate, or vaterite. The mixed calcium compounds, such as amorphous calcium carbonate, basic calcium carbonate, or vaterite, transition to phases such as calcite or aragonite, thereby exhibiting a solidification function and acting as nuclei when the carbonate-containing slurry solidifies, thereby increasing the strength of the resulting solidified body.

[0046] In this way, by blending a calcium compound such as amorphous calcium carbonate, basic calcium carbonate, or vaterite with a slurry containing calcium carbonate and solidifying the calcium carbonate, the strength of the solidified body produced can be increased, and when the solidified body is transported, even during transport accompanied by vibration, the shape of the solidified body can be maintained without being crushed or scattered, 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 calcium compound at, for example, 60 to 90°C, preferably 70 to 80°C, and / or by inducing a phase transition in water. When the calcium compound is vaterite, solidification by dissolution and reprecipitation requires water, unlike simple drying of the calcium carbonate-containing slurry containing vaterite. Therefore, complete removal of water from the slurry is not required. For solidification by dissolving and reprecipitating vaterite, the water / solid ratio in the vaterite and calcium carbonate-containing slurry can be as low as about 40%, for example, and this can be adjusted by known dehydration methods such as a filter press. For example, when drying a slurry, if fine powder is present in the dried slurry, the fine powder may scatter during transportation. However, as in the present invention, even if the solidified product contains moisture and loses moisture when left standing, scattering of the fine powder can be suppressed. 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, if necessary, can be suitably used, but is not limited to these heat sources.

[0048] 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 calcium 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 calcium carbonate can be transported at room temperature and pressure. ２ The second location may be a CO recovery location, and the second location may be a CO recovery location from the calcium solidified body. ２ It may also be a place where water is stored or utilized.

[0050] The first location may be a land 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 a land 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. 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 calcium carbonate after transport to the second location via step (c) into calcium oxide and CO ２ As a decomposition method, for example, thermal decomposition can be used. For example, by heating the solidified calcium carbonate to the decomposition temperature of the carbonate, for example, 700 to 1000°C, the solidified calcium carbonate is decomposed into calcium 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 calcium carbonate in step (d). ２ is a process of injecting CO into the ground through 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 calcium oxide produced by the decomposition in step (d) with water to produce calcium hydroxide.

[0054] In the step (g) described later, it is possible to generate calcium hydroxide at the first location and use the generated heat in the step (b). 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 calcium carbonate in a transportation means, it is preferable to generate calcium hydroxide by reacting calcium 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 calcium hydroxide obtained in step (p) to the first location. The calcium hydroxide produced in step (p) can be transported from the second location to another location by, for example, a transport means, preferably from the second location to the first location. As mentioned 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 calcium hydroxide. Furthermore, the calcium hydroxide produced 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 calcium hydroxide transported to the first location in step q as a raw material (calcium hydroxide) for the calcium carbonate-containing slurry in step (a). All or part of the calcium hydroxide produced in step (r) can be used as the calcium 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 calcium hydroxide in a transportation means, it is desirable to react calcium oxide with water to produce calcium hydroxide in step (p) as described above, which 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), the following steps (f) to (h) can be applied. Step (f) is a step of transporting the calcium oxide obtained in step (d) from the second location to the first location. As with the above, examples of transportation means include vehicles such as trucks, ships, trains, locomotives, and belt conveyors, but are not limited to these as long as calcium oxide can be transported. Furthermore, the calcium oxide can be transported at room temperature and normal pressure.

[0058] In step (g), the calcium oxide transported to the first location in step (f) is reacted with water to produce calcium hydroxide, similar to step (p). In step (h), the resulting calcium hydroxide is reacted with the CO 2 ２ This is a process in which the calcium hydroxide is recycled and reused to immobilize the calcium carbonate.

[0059] The reaction between calcium oxide and water in step (g) is an exothermic reaction, and the generated heat can be used in the solidification step in step (b). It is not particularly limited whether all or a portion of the generated heat is used in step (b). Furthermore, it is desirable to separate unreacted calcium oxide, water, etc. from the calcium hydroxide before using it in step (a) to increase its 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 used are far away, the solidified body of calcium carbonate that fixes the carbon dioxide is a solidified body with good strength, which improves ease of storage. Furthermore, when transporting, 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 normal pressure by means of transportation such as a ship or vehicle, and is thus far from the CO2 storage location as in the past. 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 calcium carbonate from an exhaust gas containing the carbonate; (c) transporting the solidified calcium carbonate from a first location to a second location; and (d) separating the solidified calcium carbonate after transportation into calcium 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 flue gas according to claim 1, wherein step (b) comprises mixing amorphous calcium carbonate and / or basic calcium carbonate and / or vaterite with the calcium carbonate-containing slurry obtained in step (a) to solidify it.

3. The step (a) comprises: (a1) CO ２ 3. The system for transporting carbon dioxide from exhaust gas 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 carbonate; and (a2) a step of reacting the carbonate of the alkali obtained in the step (a1) with a hydroxide of calcium to obtain the carbonate of calcium.

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

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

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