Carbon dioxide utilization system, and calcium carbonate production device and production method

Abstract

This carbon dioxide utilization system is provided with: a flue through which exhaust gas containing carbon dioxide passes; a spray nozzle for supplying premixed concrete sludge water to the flue; and a dust collection device that recovers a reactant containing calcium carbonate generated by a reaction between the carbon dioxide contained in the exhaust gas and the premixed concrete sludge water, the carbon dioxide utilization system utilizing the carbon dioxide contained in the exhaust gas, in addition, the amount of ready-mixed concrete sludge which is usually discarded as a waste material is reduced, and effective reuse of calcium carbonate can be achieved.

Description

Technical Field

[0001] The present invention relates to a carbon dioxide utilization system, a calcium carbonate manufacturing device and a manufacturing method. Background Art

[0002] In recent years, there has been a growing concern about global warming, and there is a demand to reduce the amount of carbon dioxide emitted into the atmosphere. Research is underway to reduce and recover the amount of exhaust gas containing carbon dioxide emitted into the atmosphere during operation in various facilities such as power plants, incinerators, cement plants, steel plants, and factory equipment. In particular, reducing carbon dioxide emissions from cement plants is considered an urgent issue.

[0003] For example, Patent Document 1 proposes a method of treating sludge water by blowing carbon dioxide into the sludge water, reacting the carbon dioxide with the hydration product in the sludge water to generate calcium carbonate, and recovering the sludge water. In addition, the following contents are disclosed: As carbon dioxide, industrial carbon dioxide, air, exhaust gas containing carbon dioxide, etc. generated during the calcination of cement clinker can be used; this is preferred from the viewpoint of suppressing the emission of carbon dioxide, etc. into the atmosphere and effectively utilizing it.

[0004] Furthermore, in Patent Document 2, as a method for manufacturing carbonate using carbon dioxide gas contained in exhaust gas as a raw material, the following method is disclosed: an alkaline aqueous solution such as a caustic soda solution is made into mist, carbon dioxide gas in the exhaust gas is absorbed in the mist, and the mist is made into a mist containing carbonate (sodium carbonate) generated by the reaction of caustic soda and carbon dioxide gas, and the mist is separated from the exhaust gas. Furthermore, a method for making calcium carbonate by reacting sodium carbonate with calcium hydroxide is also disclosed. Thus, various studies related to methods such as being able to recover carbon dioxide (carbon dioxide gas) contained in exhaust gas are currently being conducted.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2020-163821

[0008] Patent Document 2: International Publication No. 2022-014554 Pamphlet Summary of the invention

[0009] Problem that the invention aims to solve

[0010] The present invention has been completed in view of such actual conditions, and its object is to provide a carbon dioxide utilization system and a calcium carbonate manufacturing device and method that utilize carbon dioxide contained in exhaust gas, reduce the amount of ready-mixed concrete sludge that is usually discarded as waste, and achieve effective recycling of calcium carbonate.

[0011] Solutions for solving problems

[0012] In order to solve the above-mentioned problems, the present invention provides the following carbon dioxide utilization system.

[0013] 1. A carbon dioxide utilization system comprising:

[0014] a flue, through which exhaust gases containing carbon dioxide pass;

[0015] a spray nozzle for supplying ready-mixed concrete sludge water to the flue; and

[0016] The dust collecting device recovers a reaction product including calcium carbonate generated by a reaction between the carbon dioxide contained in the exhaust gas and the ready-mixed concrete sludge water.

[0017] Furthermore, the present invention provides the following carbon dioxide utilization system as a preferred embodiment.

[0018] 2. The carbon dioxide utilization system according to item 1 above, wherein the exhaust gas has a temperature of 50° C. or higher and 250° C. or lower.

[0019] 3. The carbon dioxide utilization system according to 1 or 2 above, wherein the dust collecting device is a bag filter.

[0020] 4. The carbon dioxide utilization system according to any one of 1 to 3 above, wherein the ready-mixed concrete sludge water has a relative humidity of 1 m 3 The supply amount of / h is 5kg / h or more and 600kg / h or less.

[0021] 5. The carbon dioxide utilization system according to any one of 1 to 4 above, wherein the ready-mixed concrete sludge water is obtained by removing solid components from ready-mixed concrete sludge.

[0022] 6. The carbon dioxide utilization system according to 5 above, wherein a substance obtained by removing solid components from a mixture of the solid components and water is used as ready-mixed concrete sludge water.

[0023] The present invention provides the following calcium carbonate manufacturing device.

[0024] 7. A calcium carbonate manufacturing device, comprising:

[0025] a flue, through which exhaust gases containing carbon dioxide pass;

[0026] a spray nozzle for supplying ready-mixed concrete sludge water to the flue; and

[0027] The dust collecting device recovers a reaction product including calcium carbonate generated by a reaction between the carbon dioxide contained in the exhaust gas and the ready-mixed concrete sludge water.

[0028] Furthermore, the present invention provides the following method for producing calcium carbonate.

[0029] 8. A method for producing calcium carbonate, wherein:

[0030] bringing exhaust gas containing carbon dioxide passing through a flue into contact with ready-mixed concrete sludge water supplied to the flue through a spray nozzle,

[0031] A reaction product including calcium carbonate generated by the reaction between the carbon dioxide contained in the exhaust gas and the ready-mixed concrete sludge water is recovered by a dust collecting device.

[0032] Effects of the Invention

[0033] According to the present invention, carbon dioxide contained in exhaust gas can be utilized, and the amount of ready-mixed concrete sludge that is usually discarded as waste can be reduced, and effective recycling of calcium carbonate can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a flowchart showing a preferred example of the carbon dioxide utilization system according to the present embodiment. DETAILED DESCRIPTION

[0035] Hereinafter, an embodiment of the present invention (hereinafter sometimes referred to as "the present embodiment") is described. The present invention is not limited to the following embodiments, and can be implemented with arbitrary changes within the scope that does not hinder the effect of the invention. In addition, the numerical range mark "AA to BB" in this specification means "above AA and below BB". Moreover, in this specification, the numerical values ​​involved in "above", "below" and "~" related to the description of the numerical range are numerical values ​​that can be arbitrarily combined. For example, when a certain numerical range is recorded as "CC to DD" and "EE to FF", it also includes numerical ranges such as "CC to FF" and "EE to DD".

[0036] [Carbon dioxide utilization system]

[0037] The carbon dioxide utilization system of this embodiment includes:

[0038] a flue, through which exhaust gases containing carbon dioxide pass;

[0039] a spray nozzle for supplying ready-mixed concrete sludge water to the flue; and

[0040] The dust collecting device recovers a reaction product including calcium carbonate generated by a reaction between the carbon dioxide contained in the exhaust gas and the ready-mixed concrete sludge water.

[0041] As described above, various studies are being conducted on methods for utilizing carbon dioxide (carbon dioxide gas) contained in exhaust gas, and for example, methods described in Patent Documents 1 and 2 mentioned above are disclosed.

[0042] However, the method of Patent Document 1 only focuses on removing hydration products from sludge water and reusing the sludge water as mixing water for concrete, and does not focus on the production of calcium carbonate. Therefore, in order to reuse calcium carbonate, it is necessary to dry it separately, which cannot be said to be an effective method when focusing on the utilization of calcium carbonate.

[0043] Furthermore, the method of Patent Document 2 requires the use of an alkaline aqueous solution such as a caustic soda aqueous solution and requires the use of calcium hydroxide or the like to obtain calcium carbonate, and therefore lacks perspectives such as the recycling of waste and the effective recycling of calcium carbonate.

[0044] Thus, although there are records about utilizing carbon dioxide (carbon dioxide gas) contained in the exhaust gas in Patent Documents 1 and 2, it is difficult to reduce the amount of waste of ready-mixed concrete sludge that is usually discarded as waste and to achieve effective recycling of calcium carbonate by utilizing carbon dioxide (carbon dioxide gas) in the methods described in these patent documents.

[0045] The carbon dioxide utilization system of this embodiment supplies ready-mixed concrete sludge water to exhaust gas containing carbon dioxide to make them contact, thereby causing a reaction between carbon dioxide and ready-mixed concrete sludge water. As a result, the carbon dioxide contained in the exhaust gas can be utilized, and the amount of ready-mixed concrete sludge that is usually discarded as waste can be reduced.

[0046] Furthermore, in the system of this embodiment, the ready-mixed concrete sludge water is sprayed and supplied to the exhaust gas through the spray nozzle. As a result, the ready-mixed concrete sludge water is easily contacted with the carbon dioxide in the exhaust gas, and the carbon dioxide can be effectively absorbed into the ready-mixed concrete sludge water. The calcium components such as calcium hydroxide contained in the ready-mixed concrete sludge water react easily with the carbon dioxide, thereby promoting the generation of reactants including calcium carbonate. In addition, due to the heat of the exhaust gas, the water contained in the ready-mixed concrete sludge water becomes water vapor and is directly discharged into the atmosphere. The calcium carbonate is recovered in a dry state in the dust collector due to the heat of the exhaust gas, so that the calcium carbonate can be effectively produced and effectively reused.

[0047] As described above, the carbon dioxide utilization system of the present embodiment utilizes carbon dioxide contained in the exhaust gas, reduces the amount of ready-mixed concrete sludge that is usually discarded as waste, and can realize effective recycling of calcium carbonate.

[0048] Below, use Figure 1 A carbon dioxide utilization system (hereinafter, sometimes simply referred to as a “system”) according to the present embodiment will be described. Figure 1 This is a diagram showing a preferred example of the carbon dioxide utilization system according to the present embodiment.

[0049] exist Figure 1 The carbon dioxide utilization system of this embodiment is shown in FIG. 1 and includes a flue for passing exhaust gas, a spray nozzle for supplying ready-mixed concrete sludge water to the flue, and a dust collecting device for recovering a reaction product including calcium carbonate. Figure 1 The system shown is provided with a sludge water storage tank for storing ready-mixed concrete sludge water, and a guide blower and a chimney for discharging exhaust gas from which the reactants have been recovered by a dust collecting device into the atmosphere.

[0050] [a flue for the passage of exhaust gases containing carbon dioxide]

[0051] (Smoke duct)

[0052] The carbon dioxide utilization system of the present embodiment is provided with a flue for exhaust gas containing carbon dioxide to pass through. A flue generally refers to a pipe or conduit for guiding exhaust gas discharged from a power plant, a cement plant, a precast concrete (PCa) product plant, an asphalt plant, a steel plant, an incinerator, other factory equipment, a boiler equipped with these various equipment, etc., to a chimney.

[0053] In the system of the present embodiment, the flue is not particularly limited as long as it can pass exhaust gas containing carbon dioxide, and may be a newly installed flue, and if the reduction of equipment cost is taken into consideration, it may also be an existing flue that is installed to discharge exhaust gas discharged from a power plant, a cement plant, a precast concrete (PCa) product plant, an asphalt plant, a steel plant, an incinerator, other factory equipment, a boiler equipped with these various equipment, etc. If it is considered that the system of the present embodiment uses ready-mixed concrete sludge water, it is preferred to use an existing flue that is installed in a precast concrete (PCa) product plant to discharge exhaust gas as the flue. Therefore, the system of the present embodiment preferably exists in the form of being assembled to a precast concrete (PCa) product plant.

[0054] (Exhaust gas)

[0055] As exhaust gas containing carbon dioxide, as mentioned above, exhaust gas discharged from various factory equipment (also referred to as "combustion exhaust gas") can be representatively cited. As the concentration of carbon dioxide contained in these exhaust gases, for example, if it is combustion exhaust gas from a power plant, it is generally 8 to 15% by volume, if it is combustion exhaust gas from a precast concrete (PCa) product factory, asphalt factory, or incinerator, it is generally 1 to 30% by volume, if it is combustion exhaust gas from a cement factory, it is generally 15 to 30% by volume, and if it is exhaust gas from a steel plant, it is generally 20 to 30% by volume. In the system of this embodiment, any combustion exhaust gas can be used.

[0056] Among the above, if ready-mixed concrete sludge water is considered to be used, combustion exhaust gas exhausted in the calcination process in a precast concrete (PCa) product factory is preferred.

[0057] The temperature condition of the exhaust gas may vary depending on the place where the exhaust gas is used, so it cannot be generalized. The temperature of the part where the ready-mixed concrete sludge water is supplied can be 50° C. or more and 250° C. or less. In order to remove water from the ready-mixed concrete sludge water that has generated a reactant containing calcium carbonate and recover the calcium carbonate in a dry state in a dust collector, thereby more effectively reusing the calcium carbonate, it is preferably 75° C. or more, more preferably 100° C. or more, and further preferably 110° C. or more. As an upper limit, it can be 250° C. or less. In addition, when a plurality of spray nozzles are provided, the temperature condition of the exhaust gas is the temperature of the part where the concrete sludge water first contacts the exhaust gas, that is, the temperature of the part of the spray nozzle provided most upstream in the flow direction of the exhaust gas in the flue.

[0058] In the system of this embodiment, if Figure 1 As shown, a spray nozzle is installed on the flue, and a reactant containing calcium carbonate is generated by contact between carbon dioxide contained in the exhaust gas passing through the flue and the ready-mixed concrete sludge water sprayed from the spray nozzle. Then, the generated reactant containing calcium carbonate passes through the flue together with the exhaust gas and is recovered in a dry state in a dust collecting device.

[0059] [Spray nozzle for supplying sludge water to ready-mixed concrete]

[0060] (Ready-mixed concrete sludge water)

[0061] In a ready-mixed concrete plant, there are excess concrete produced in excess of the ordered quantity but not shipped, returned concrete that was not used at the supply destination and their dissolved products, and ready-mixed concrete sludge containing cement, such as cleaning discharge water generated by cleaning equipment such as mixer trucks. In the system of this embodiment, the ready-mixed concrete sludge generated in the ready-mixed concrete plant can be used as ready-mixed concrete sludge water.

[0062] Ready-mixed concrete sludge generally contains water, calcium components such as calcium hydroxide dissolved in water, and solid components of sludge (mainly including hydration products, aggregate particles, etc.). Then, the solid components are sometimes removed from the ready-mixed concrete sludge, and the mixture is separated into a supernatant containing calcium hydroxide and the like and sludge water containing solid components of sludge (mainly including hydration products, aggregate particles, etc.). In this case, both the supernatant and the sludge water can be used as ready-mixed concrete sludge water.

[0063] When the ready-mixed concrete sludge water used in the system of the present embodiment is any of the above-mentioned supernatant water and sludge water, in consideration of suppressing clogging of the spray nozzle and stably operating the system for a longer period of time, the solid content concentration in the ready-mixed concrete sludge water is preferably 20% by mass or less, more preferably 10% by mass or less, further preferably 5% by mass or less, and further preferably 1% by mass or less.

[0064] As described above, in the ready-mixed concrete sludge water, calcium hydroxide is dissolved and exists as a calcium component, but the solubility of calcium hydroxide is low, so it also exists as a solid component. In addition, as a calcium component, calcium carbonate and the like are also included, which mainly exist as a solid component. Thus, in the ready-mixed concrete sludge water used in the system of the present embodiment, as a solid component, calcium components such as calcium hydroxide and calcium carbonate are included, and as described above, solid components of sludge (mainly including hydration products, aggregate particles, etc.) are included. Moreover, in the system of the present embodiment, these solid components contained in the ready-mixed concrete sludge water and the calcium carbonate rapidly generated by the spraying of the ready-mixed concrete sludge water into the exhaust gas exist as tiny particles, which become the growth nuclei of crystals, thereby promoting the generation of calcium carbonate.

[0065] Therefore, in the system of the present embodiment, in order to suppress the clogging of the spray nozzle and to operate the system stably for a longer period of time, as described above, it is preferred that the solid content contained in the ready-mixed concrete sludge water is small. On the other hand, from the viewpoint of acting as a growth nucleus of crystals and promoting the formation of calcium carbonate, the solid content concentration in the ready-mixed concrete sludge water is preferably 0.001% by mass or more, more preferably 0.0015% by mass or more, and further preferably 0.002% by mass or more.

[0066] From the same viewpoint, the particle size of the solid content in the ready-mixed concrete sludge water is preferably 1000 μm or less, more preferably 100 μm or less, further preferably 10 μm or less, further preferably 1 μm or less, and particularly preferably 0.1 μm or less.

[0067] When the ready-mixed concrete sludge water used in the system of the present embodiment is the above-mentioned supernatant, the concentration of the calcium component contained in the ready-mixed concrete sludge water is usually 100 mg / L or more, preferably 250 mg / L or more, more preferably 500 mg / L or more, and further preferably 800 mg / L or more. As the upper limit, the higher the better, and there is no particular restriction, but it is usually 1500 mg / L or less.

[0068] Furthermore, when the ready-mixed concrete sludge water is the above-mentioned sludge water, the concentration of the calcium component contained in the ready-mixed concrete sludge water is usually 1000 mg / L or more, preferably 5000 mg / L or more, more preferably 10000 mg / L or more, and further preferably 30000 mg / L or more. As the upper limit, the higher the more preferred, there is no particular restriction, but it is usually 150000 mg / L or less.

[0069] Furthermore, as the ready-mixed concrete sludge water, a substance obtained by removing the solid component from a mixture obtained by mixing the solid component obtained from the ready-mixed concrete sludge and water can also be used. The solid component contains calcium components such as calcium hydroxide, and the hydration products mainly contained in the solid component contain calcium components such as calcium hydroxide and calcium silicate hydrate. Therefore, the substance obtained by removing the solid component from the mixture also contains calcium components dissolved in water from the solid component, and more calcium components can be converted into calcium carbonate from the ready-mixed concrete sludge.

[0070] (Spray Nozzle)

[0071] The spray nozzle is used to supply the ready-mixed concrete sludge water to the flue. The ready-mixed concrete sludge water is supplied to the flue while being sprayed by the spray nozzle, that is, it is supplied to the flue in the form of particles. Therefore, as described above, the ready-mixed concrete sludge water easily contacts the carbon dioxide in the exhaust gas, and the carbon dioxide can be effectively absorbed into the ready-mixed concrete sludge water, and calcium carbonate can be easily generated by the reaction of the calcium component and the carbon dioxide. Furthermore, the evaporation of water is also effectively performed, so that calcium carbonate can be obtained in a dry state without including a drying process.

[0072] The spray nozzle is not particularly limited as long as it is a nozzle capable of spraying ready-mixed concrete sludge water, and a commercially available nozzle or the like can be used. For example, a single-fluid nozzle that sprays only ready-mixed concrete sludge water can be used, and a multi-fluid nozzle such as a two-fluid nozzle that sprays ready-mixed concrete sludge water together with a gas such as air can be used as needed. Furthermore, as needed, a nozzle having a mechanism that makes the spray particles finer by generating ultrasonic waves (also called an "ultrasonic spray nozzle") can also be used.

[0073] The spray pattern of the spray nozzle can be adopted without particular limitation, and representative examples thereof include full cone, hollow cone (hollow cone), flat (fan-shaped), solid (straight), etc. Also, the spray angle of the spray nozzle can be adopted without particular limitation, and is preferably 60° or more, more preferably 90° or more, and the upper limit is preferably 145° or less, more preferably 140° or less.

[0074] In the system of this embodiment, as a spray nozzle, from the viewpoint of ensuring a better spray state and promoting the reaction caused by the contact between carbon dioxide in the exhaust gas and the calcium component contained in the ready-mixed concrete sludge water, it is preferred to use a spray nozzle having a hollow cone (hollow cone) with a large spray angle and a flat (fan-shaped) spray pattern.

[0075] The hole diameter of the spray port of the ready-mixed concrete sludge water in the spray nozzle may vary depending on the number of spray ports of the spray nozzle, the supply amount of the ready-mixed concrete sludge water, etc., and therefore cannot be generalized, but from the viewpoint of ensuring a better spray state, it is preferably 0.1 mm or more, more preferably 0.3 mm or more, and further preferably 0.5 mm or more, and the upper limit is preferably 5.0 mm or less, more preferably 4.0 mm or less, and further preferably 3.0 mm or less.

[0076] In the system of this embodiment, the number of spray nozzles to be set may vary depending on the size of the spray nozzle, the aperture and number of the spray ports of the spray nozzle, the supply amount of ready-mixed concrete sludge water, etc., and therefore cannot be generalized, but as long as there is more than one, the upper limit is usually 10 or less, preferably 8 or less, and more preferably 5 or less.

[0077] The spray nozzle is not particularly limited in its location as long as it can supply ready-mixed concrete sludge water to the flue. Figure 1As shown, it is preferably directly installed in the flue. At this time, when the cross section of the flue in the vertical direction is circular, the installation position of the spray nozzle is preferably set on the semicircle of the upper half of the circle (within ±90° when the uppermost point is set to 0°), more preferably within ±60°, further preferably within ±30°, further preferably within ±15°, and particularly preferably at the uppermost point. In addition, when the flue is a square duct, the above circular pipe (or duct) is also followed.

[0078] When a plurality of spray nozzles are provided, the plurality of spray nozzles may be provided on the circle of the same cross section, for example, they may be provided sequentially at the uppermost point toward the flow direction of the exhaust gas.

[0079] From the viewpoint of promoting the reaction caused by the contact between carbon dioxide in the exhaust gas and the calcium component contained in the ready-mixed concrete sludge water, the spray particles of the ready-mixed concrete sludge water sprayed by the spray nozzle are preferably finer. The particle size of the spray particles is preferably 200 μm or less, more preferably 120 μm or less, further preferably 80 μm or less, and further preferably 50 μm or less.

[0080] The amount of ready-mixed concrete sludge water supplied to the flue may vary depending on the flow rate of exhaust gas passing through the flue, the size of the flue, etc., so it cannot be generalized. 3 The feed rate of the reaction product of calcium carbonate can be more than 10 kg / h, more preferably more than 20 kg / h, more preferably more than 100 kg / h, and as the upper limit, can be less than 500 kg / h. In addition, when a plurality of spray nozzles are provided, the above-mentioned feed rate is the feed rate supplied from all spray nozzles.

[0081] (Sludge water storage tank)

[0082] Considering the operational stability of the system of this embodiment, the ready-mixed concrete sludge water is preferably temporarily stored in a tank and then supplied to the flue through a spray nozzle. That is, the system of this embodiment preferably includes a sludge water storage tank for storing the ready-mixed concrete sludge water.

[0083] By temporarily storing the ready-mixed concrete sludge water in the sludge water storage tank, it is not only easy to cope with the change in the required amount, but also easy to spray a certain amount from the spray nozzle, so that the exhaust gas in the flue gas and the ready-mixed concrete sludge water are in contact with each other stably, thereby stabilizing the generation of calcium carbonate based on the reaction of carbon dioxide and calcium components, and as a result, effective reuse of calcium carbonate can be achieved. In addition, when the operation of the system is stopped, the ready-mixed concrete sludge water can be stored in advance until the next operation, so the operation of the system can be carried out earlier.

[0084] As long as the sludge water storage tank can be used without special restrictions as long as it can store sludge water, for example, it can be a tank body installed above ground or underground, such as an above-ground storage tank, an underground storage tank, etc., and it can be selected from various roof-type storage tanks called fixed roof type and floating roof type, as well as horizontal and vertical storage tanks such as horizontal cylindrical and vertical cylindrical types.

[0085] Furthermore, the sludge water storage tank may be a newly installed one or an existing one may be used.

[0086] The sludge water storage tank is preferably equipped with a stirrer. Since the ready-mixed concrete sludge water may contain solid components, by providing a stirrer, solidification of the solid components can be suppressed.

[0087] Furthermore, the sludge water storage tank may be equipped with various instruments such as a level gauge and a regulating valve for regulating the supply amount of the ready-mixed concrete sludge water supplied to the sludge water storage tank by the level gauge.

[0088] (chimney)

[0089] The carbon dioxide utilization system of this embodiment preferably includes a chimney. By including a chimney, exhaust gas can be discharged more quickly based on the chimney effect, and even when an induction blower is provided, the power applied to the induction blower can be reduced.

[0090] As a chimney, any structure that can discharge exhaust gas into the atmosphere can be adopted without particular limitation, for example, a single chimney, a double chimney such as a heat-insulated double chimney, a hollow double chimney, etc. can be adopted. In the system of the present embodiment, when it is set outdoors, it is preferred to adopt a double chimney from the viewpoint of suppressing the temperature drop of the exhaust gas and enabling more stable exhaust.

[0091] It may be newly installed for the system of this embodiment, or it may be an existing chimney like the flue described above. If it is considered that the system of this embodiment uses ready-mixed concrete sludge water, it is preferable to use an existing chimney installed in a ready-mixed concrete plant to discharge exhaust gas into the atmosphere as the chimney.

[0092] [Dust collection device for recovering reactants]

[0093] The carbon dioxide utilization system of this embodiment is equipped with a dust collecting device for recovering the reactant containing the calcium carbonate generated in the flue. As described above, the exhaust gas passes through the dust collecting device along with the calcium carbonate generated in the flue, so that the accompanying calcium carbonate is recovered, and the recovered calcium carbonate is reused. In addition, the exhaust gas after the calcium carbonate is recovered is released into the atmosphere.

[0094] (Dust collection device)

[0095] As the dust collector, various dust collectors such as dry electric dust collectors, wet electric dust collectors, and filtering dust collectors (bag filters) can be used. In the system of this embodiment, if the reduction of power consumption and the ease of handling are considered, the filtering dust collector (bag filter) is preferred.

[0096] As a filter for filtering dust collection devices (bag filters), any filter can be used without particular limitation, and examples include filters made of raw materials such as polypropylene, nylon, acrylic, polyester, cotton, wool, heat-resistant nylon, glass fiber, PTFE (polytetrafluoroethylene), etc., and filters with additional functions such as electrostatic filters can also be used.

[0097] The bag filter may include a scavenging unit, and preferably, for example, a unit using a pulsating back pressure method or a pulse jet method is used. Among them, a unit using a pulse jet method is preferred.

[0098] (Reactants containing calcium carbonate)

[0099] In the carbon dioxide utilization system of this embodiment, the reactant containing calcium carbonate is recovered in the dust collector. The reactant containing calcium carbonate mainly contains calcium carbonate generated by the reaction of carbon dioxide contained in the exhaust gas and calcium components contained in the ready-mixed concrete sludge water.

[0100] The concentration of calcium carbonate contained in the reactant containing calcium carbonate is usually 90 mass % or more, further becomes 92 mass % or more, 95 mass % or more. In this way, the concentration of calcium carbonate in the reactant containing calcium carbonate obtained by the system of this embodiment becomes extremely high.

[0101] The reaction product containing calcium carbonate recovered by the system of the present embodiment can be preferably used for applications such as fillers used in cement compositions, mortar, concrete, asphalt, and the like, and building materials.

[0102] The calcium carbonate generated in the carbon dioxide utilization system of the present embodiment can be used alone or mixed with other fillers such as calcium carbonate. In addition, when used in the above-mentioned applications, by performing mass balance certification on the calcium carbonate, it can contribute to carbon neutrality according to the amount of calcium carbonate used obtained by the carbon dioxide utilization system of the present embodiment.

[0103] Ready-mixed concrete sludge water also contains sodium, sulfur, etc., so the reactant containing calcium carbonate may also contain impurities generated by these. The content of impurities contained in the reactant containing calcium carbonate is usually less than 10% by mass, and further less than 8% by mass, less than 5% by mass, less than 3% by mass, and less than 1% by mass. Since the content of impurities is so small, there is no problem in using it in the above-mentioned applications.

[0104] (Guided Blower)

[0105] In the system of this embodiment, if Figure 1 As shown, a guide blower can be provided on a pipeline downstream of the exhaust port of the filter to forcibly exhaust the gas exhausted from the exhaust port. By exhausting the gas using the guide blower, etc., the filtration in the bag filter is smoothly performed, and a stable fluidized layer of the medium particles in the fluidized dryer is obtained, so that the reactant containing calcium carbonate can be recovered in a shorter time.

[0106] [Calcium carbonate production device]

[0107] The calcium carbonate manufacturing device of the present embodiment is the following calcium carbonate manufacturing device, which has:

[0108] a flue, through which exhaust gases containing carbon dioxide pass;

[0109] a spray nozzle for supplying ready-mixed concrete sludge water to the flue; and

[0110] The dust collecting device recovers a reaction product including calcium carbonate generated by a reaction between the carbon dioxide contained in the exhaust gas and the ready-mixed concrete sludge water.

[0111] According to the manufacturing device of calcium carbonate of the present embodiment, exhaust gas containing carbon dioxide and ready-mixed concrete sludge water can be utilized, so that carbon dioxide contained in the exhaust gas can be utilized, and the amount of ready-mixed concrete sludge that is usually discarded as waste can be reduced. In addition, by spraying the concrete sludge water into the exhaust gas through a spray nozzle, the ready-mixed concrete sludge water and carbon dioxide are easily contacted, and carbon dioxide can be effectively absorbed into the ready-mixed concrete sludge water, and calcium components such as calcium hydroxide and carbon dioxide are easily reacted. In addition, due to the heat of the exhaust gas, the water contained in the ready-mixed concrete sludge water is removed in the form of water vapor, and calcium carbonate is obtained in the form of powder, so it can be easily recovered by a dust collector. Therefore, calcium carbonate can be effectively manufactured and effectively reused.

[0112] The exhaust gas containing carbon dioxide, the flue, the ready-mixed concrete sludge water, the spray nozzle, the reaction product containing calcium carbonate generated by the reaction of carbon dioxide and the ready-mixed concrete sludge water, and the dust collecting device are the same as those described in the above-mentioned carbon dioxide utilization system.

[0113] As described above, the calcium carbonate obtained by the manufacturing device of the calcium carbonate of the present embodiment can be preferably utilized in the purposes of the filler, building materials etc. used in cement composition, mortar, concrete, asphalt etc. When using in these purposes, by carrying out mass balance certification to calcium carbonate, it is possible to contribute to carbon neutrality according to the usage amount of the calcium carbonate obtained by the carbon dioxide utilization system of the present embodiment.

[0114] [Method for producing calcium carbonate]

[0115] The manufacturing method of calcium carbonate of the present embodiment is the manufacturing method of calcium carbonate as follows:

[0116] bringing exhaust gas containing carbon dioxide passing through a flue into contact with ready-mixed concrete sludge water supplied to the flue through a spray nozzle,

[0117] A reaction product including calcium carbonate generated by the reaction between the carbon dioxide contained in the exhaust gas and the ready-mixed concrete sludge water is recovered by a dust collecting device.

[0118] According to the method for manufacturing calcium carbonate of the present embodiment, exhaust gas containing carbon dioxide and ready-mixed concrete sludge water can be utilized, so that the carbon dioxide contained in the exhaust gas can be utilized, and the amount of ready-mixed concrete sludge that is usually discarded as waste can be reduced. In addition, by spraying the concrete sludge water into the exhaust gas via a spray nozzle, the ready-mixed concrete sludge water and carbon dioxide are easily contacted, and carbon dioxide can be effectively absorbed into the ready-mixed concrete sludge water, and calcium components such as calcium hydroxide and carbon dioxide are easily reacted. In addition, due to the heat of the exhaust gas, the water contained in the ready-mixed concrete sludge water is removed in the form of water vapor, and calcium carbonate is obtained in the form of powder, so it can be easily recovered by a dust collector. Therefore, calcium carbonate can be effectively manufactured and effectively reused.

[0119] The exhaust gas containing carbon dioxide, the flue, the ready-mixed concrete sludge water, the spray nozzle, the reaction product containing calcium carbonate generated by the reaction of carbon dioxide and the ready-mixed concrete sludge water, and the dust collecting device are the same as those described in the above-mentioned carbon dioxide utilization system.

[0120] Furthermore, various conditions such as the supply amount of ready-mixed concrete sludge water and the temperature of exhaust gas are also the same as those described in the above-mentioned carbon dioxide utilization system.

[0121] As described above, the calcium carbonate obtained by the manufacture method of the calcium carbonate of the present embodiment can be preferably utilized in the purposes of fillers, building materials, etc. used in cement compositions, mortar, concrete, asphalt, etc. When used in these purposes, by carrying out mass balance certification to calcium carbonate, it is possible to contribute to carbon neutrality according to the usage amount of the calcium carbonate obtained by the carbon dioxide utilization system of the present embodiment.

[0122] Example

[0123] Next, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples at all.

[0124] Used with Figure 1 A calcium carbonate manufacturing device having the structure shown.

[0125] The exhaust gas (carbon dioxide concentration: 26% by volume, temperature: 60°C) was discharged from the nozzle (nozzle hole diameter: 0.5 mm φ) at a rate of 4 L / min (0.24 m 3 / h) through a flue (diameter: 100mm), and sprayed (spray particle size: 10-50μm) ready-mixed concrete sludge water (calcium concentration: 900mg / L, solid content concentration: 0.0022% by mass, solid content particle size: 1-10μm) at a flow rate of 88g / min (5.3kg / h). The powder recovered by the dust collector (bag filter) was analyzed and confirmed to be calcium carbonate powder (purity: 96%).

Claims

1. A carbon dioxide utilization system comprising: a flue, through which exhaust gases containing carbon dioxide pass; a spray nozzle for supplying ready-mixed concrete sludge water to the flue; and The dust collecting device recovers a reaction product including calcium carbonate generated by a reaction between the carbon dioxide contained in the exhaust gas and the ready-mixed concrete sludge water.

2. The carbon dioxide utilization system according to claim 1, wherein: The temperature of the exhaust gas is 50° C. or higher and 250° C. or lower.

3. The carbon dioxide utilization system according to claim 1 or 2, wherein: The dust collecting device is a bag filter.

4. The carbon dioxide utilization system according to claim 1 or 2, wherein: The ready-mixed concrete sludge water is relative to the exhaust gas 1m 3 The supply amount of / h is 5kg / h or more and 600kg / h or less.

5. The carbon dioxide utilization system according to claim 1 or 2, wherein: The ready-mixed concrete sludge water is a substance obtained by removing solid components from ready-mixed concrete sludge.

6. The carbon dioxide utilization system according to claim 5, wherein: A mixture obtained by removing the solid component from the mixture of the solid component and water is used as ready-mixed concrete sludge water.

7. A calcium carbonate manufacturing device, comprising: a flue, through which exhaust gases containing carbon dioxide pass; a spray nozzle for supplying ready-mixed concrete sludge water to the flue; and The dust collecting device recovers a reaction product including calcium carbonate generated by a reaction between the carbon dioxide contained in the exhaust gas and the ready-mixed concrete sludge water.

8. A method for producing calcium carbonate, wherein: bringing exhaust gas containing carbon dioxide passing through a flue into contact with ready-mixed concrete sludge water supplied to the flue through a spray nozzle, A reaction product including calcium carbonate generated by the reaction between the carbon dioxide contained in the exhaust gas and the ready-mixed concrete sludge water is recovered by a dust collecting device.

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