Carbonated slurry manufacturing system

Abstract

Provided is a carbonated slurry production system capable of immobilizing carbon dioxide in a slurry comprising calcium-containing powder and water, and capable of easily controlling the average residence time of the slurry. A carbonated slurry manufacturing system (1) includes: a slurry tank (2) having first slurry containing portions (10a), (10b) for bringing the slurry into contact with a carbon dioxide-containing gas; a slurry supply device (7) for supplying a slurry comprising calcium-containing powder and water; a carbon dioxide-containing gas supply device (4) for supplying the carbon dioxide-containing gas at a pressure greater than atmospheric pressure to gas phases (9a, 9b) comprising the carbon dioxide-containing gas in the first slurry accommodating portion; a carbonated slurry discharge device (5) for discharging the carbonated slurry; liquid level measurement means (6a), (6b), (6c) for measuring the height of the liquid level comprising the slurry; and a slurry control device (7) for controlling the average residence time of the slurry on the basis of the respective heights of the first liquid level (8a), (8b) and the second liquid level (11).

Description

Technical Field

[0001] This invention relates to a carbonation slurry manufacturing system. Background Technology

[0002] In recent years, reducing carbon dioxide emissions has become an important issue in order to curb global warming.

[0003] Relatedly, a technology for immobilizing carbon dioxide recovered from waste gas generated in cement manufacturing plants into concrete and the like has been studied.

[0004] On the other hand, from the perspective of resources and environmental protection, the incineration ash generated when burning general waste, industrial waste and other urban garbage, as well as the calcium-containing powder such as clinker dust generated by cement plants, are effectively reused as cement raw materials.

[0005] Patent Document 1 discloses a method for treating chlorine-containing ash, which is used to appropriately utilize incinerator ash, clinker dust, etc. as cement raw materials, and for removing chlorine contained in incinerator ash, clinker dust, etc. The method comprises: a washing step in which water is added to the chlorine-containing ash and the mixture is stirred and washed; a slurry concentration step in which a polymeric coagulant is added to the slurry obtained after the washing step and the mixture is allowed to settle and separate; a first dewatering step in which the concentrated slurry of ash discharged from the concentration step is dewatered using a vacuum belt filter; a high-level desalination step in which the dewatered filter cake of ash discharged from the dewatering step is dispersed with water and a gas containing carbon dioxide is added while heating; and a second dewatering step in which the slurry obtained after the high-level desalination step is dewatered using a filter press to produce a cleaned ash filter cake.

[0006] In addition, as a method to effectively contact quicklime with carbon dioxide and to well control and promote the carbonation reaction, Patent Document 2 describes a method for manufacturing calcium carbonate, which includes mixing a liquid containing calcium hydroxide and an additive with waste gas containing carbon dioxide through an injector and supplying it to a reaction tank, wherein the liquid containing calcium hydroxide is a reaction liquid circulated from the reaction tank.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent No. 6252653

[0010] Patent Document 2: Japanese Patent No. 5426982 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] The purpose of this invention is to provide a carbonation slurry manufacturing system that can continuously and efficiently immobilize carbon dioxide in a slurry composed of calcium-containing powder and water, thereby enabling easy and stable control of the average residence time of the slurry (the average time from when the slurry is supplied until it is discharged as a carbonation slurry).

[0013] Methods for solving problems

[0014] In order to solve the above-mentioned problems, the inventors conducted in-depth research and found that the above-mentioned objectives can be achieved by the following carbonated slurry manufacturing system, thus completing the present invention. The carbonated slurry manufacturing system includes: a slurry tank for containing slurry; a slurry supply device for continuously supplying slurry to the slurry tank; a carbon dioxide-containing gas supply device for supplying carbon dioxide-containing gas; a carbonated slurry discharge device for continuously discharging carbonated slurry; a liquid level measuring unit for measuring the height of the liquid surface formed by the slurry; and a slurry control device for controlling the average residence time of the slurry. The carbonated slurry manufacturing system adjusts the amount of slurry supplied per unit time and the amount of carbonated slurry discharged per unit time based on the heights of the first liquid surface and the second liquid surface measured by the liquid level measuring unit, thereby controlling the average residence time of the slurry.

[0015] That is, the present invention provides the following [1] to [6].

[0016] [1] A carbonated slurry manufacturing system for manufacturing a carbonated slurry, wherein the carbonated slurry is produced by carbonizing a slurry containing calcium powder and water using a carbon dioxide-containing gas, the carbonated slurry manufacturing system being characterized in that it comprises: a slurry tank for containing the slurry; a slurry supply device for continuously supplying the slurry to the slurry tank; a carbon dioxide-containing gas supply device for supplying the carbon dioxide-containing gas; a carbonated slurry discharge device for continuously discharging the carbonated slurry from the slurry tank; a liquid level measuring unit for measuring the height of the liquid level formed by the slurry in the slurry tank; and a slurry control device for controlling the average residence time of the slurry, wherein the slurry tank has: a first slurry receiving portion for receiving the slurry and the carbon dioxide-containing gas in such a manner that the gas phase formed by the carbon dioxide-containing gas is located above the first liquid level of the slurry, so that the slurry... The first slurry container is in contact with the aforementioned carbon dioxide-containing gas; and a second slurry container is provided such that the gas phase is located above the second liquid surface of the slurry, and does not have a contact surface between the slurry and the aforementioned carbon dioxide-containing gas. The aforementioned carbon dioxide-containing gas supply device supplies the aforementioned carbon dioxide-containing gas to the gas phase composed of the aforementioned carbon dioxide-containing gas in the first slurry container at a pressure greater than atmospheric pressure. The aforementioned liquid level measuring unit measures the height of the first liquid level in the first slurry container and the height of the second liquid level in the second slurry container. The aforementioned slurry control device adjusts the amount of slurry supplied per unit time from the aforementioned slurry supply device and the amount of carbonated slurry discharged per unit time from the aforementioned carbonated slurry discharge device based on the height of the first liquid level in the first slurry container and the height of the second liquid level in the second slurry container measured by the aforementioned liquid level measuring unit, thereby controlling the average residence time of the slurry.

[0017] [2] The carbonated slurry manufacturing system as described in [1] above, wherein the carbonated slurry manufacturing system includes a slurry circulation path for returning at least a portion of the carbonated slurry discharged from the slurry tank to the slurry tank for circulation.

[0018] [3] The carbonated slurry manufacturing system as described in [1] or [2] above, wherein the slurry tank has a stirring unit for stirring and mixing the carbonated slurry in the slurry tank.

[0019] [4] The carbonated slurry manufacturing system as described in any one of [1] to [3] above, wherein the carbonated slurry manufacturing system includes a pH measuring unit for measuring the pH of the carbonated slurry.

[0020] [5] The carbonated slurry manufacturing system as described in any one of [1] to [4] above, wherein the carbonated slurry manufacturing system includes a liquid temperature adjustment unit for adjusting the liquid temperature of the carbonated slurry.

[0021] [6] A method for manufacturing a carbonated slurry, which is a method for manufacturing a carbonated slurry, wherein the carbonated slurry is obtained by carbonated slurry containing calcium powder and water using a carbon dioxide-containing gas, the method being characterized in that it includes: a slurry preparation step, wherein the calcium powder is mixed with the water to obtain the slurry; a slurry supply step, wherein the slurry is continuously supplied to a slurry tank for containing the slurry; a slurry containing step, wherein the slurry and the carbon dioxide-containing gas are contained in a first slurry containing portion of the slurry tank such that the gas phase of the carbon dioxide-containing gas is located above a first liquid surface of the slurry, and contained in a second liquid surface of the slurry such that the gas phase is located above a second liquid surface of the slurry and there is no contact surface between the slurry and the carbon dioxide-containing gas. The above-mentioned slurry tank has a second slurry containing portion; a carbonic acid slurry preparation step, in which the carbon dioxide-containing gas is supplied to the gas phase composed of the above-mentioned carbon dioxide-containing gas in the first slurry containing portion at a pressure greater than atmospheric pressure, so that the first liquid surface comes into contact with the gas phase, thereby carbonizing the slurry to obtain a carbonic acid slurry; a carbonic acid slurry discharge step, in which the carbonic acid slurry is continuously discharged from the above-mentioned slurry tank; and a liquid level measurement step, in which the height of the first liquid level in the first slurry containing portion and the height of the second liquid level in the second slurry containing portion are measured, and based on the measurement results obtained in the liquid level measurement step, the supply amount of the slurry per unit time in the slurry supply step and the discharge amount of the carbonic acid slurry per unit time in the carbonic acid slurry discharge step are adjusted.

[0022] Invention Effects

[0023] According to the carbonated slurry manufacturing system of the present invention, carbon dioxide can be continuously and efficiently immobilized in a slurry containing calcium powder and water, thereby enabling easy and stable control of the average residence time of the slurry (the average time from when the slurry is supplied until it is discharged as carbonated slurry). Attached Figure Description

[0024] Figure 1 This is a schematic diagram illustrating an example of the carbonated slurry manufacturing system of the present invention.

[0025] Figure 2 This is a schematic diagram illustrating an example of the carbonated slurry manufacturing system of the present invention. Detailed Implementation

[0026] The carbonated slurry manufacturing system of the present invention is for manufacturing a carbonated slurry formed by carbonated slurry containing calcium powder and water using a carbon dioxide-containing gas. The carbonated slurry manufacturing system of the present invention includes: a slurry tank for containing slurry; a slurry supply device for continuously supplying slurry to the slurry tank; a carbon dioxide-containing gas supply device for supplying carbon dioxide-containing gas; a carbonated slurry discharge device for continuously discharging carbonated slurry from the slurry tank; a liquid level measuring unit for measuring the height of the liquid level formed by the slurry in the slurry tank; and a slurry control device for controlling the average residence time of the slurry. The slurry tank has: a first slurry containing portion for containing slurry and carbon dioxide-containing gas such that a gas phase composed of carbon dioxide-containing gas is located above a first liquid level of the slurry, thereby contacting the slurry with the carbon dioxide-containing gas; and a second slurry containing portion for containing slurry such that a gas phase is located above a second liquid level of the slurry, and without a contact surface between the slurry and the carbon dioxide-containing gas. The aforementioned carbon dioxide-containing gas supply device supplies carbon dioxide-containing gas to the gas phase of the first slurry container at a pressure greater than atmospheric pressure. The aforementioned liquid level measuring unit measures the height of the first liquid level in the first slurry container and the height of the second liquid level in the second slurry container. Based on the heights of the first liquid level in the first slurry container and the second liquid level in the second slurry container as measured by the liquid level measuring unit, the aforementioned slurry control device adjusts the amount of slurry supplied per unit time from the slurry supply device and the amount of carbonated slurry discharged per unit time from the carbonated slurry discharge device, thereby controlling the average residence time of the slurry.

[0027] It should be noted that in this specification, "carbonation" refers to the absorption and immobilization of carbon dioxide.

[0028] The following is for reference Figures 1-2 The carbonated slurry manufacturing systems 1 and 21 of the present invention will be described in detail.

[0029] In this invention, the slurry to be carbonated is a mixture (slurry) containing calcium powder and water.

[0030] There are no particular limitations on the use of calcium-containing powders. Examples include cement, crushed waste concrete, powdered slag from ready-mixed concrete, powdered blast furnace slag, municipal solid waste incineration ash (fly ash, main ash), and cement kiln ash. One type can be used alone, or two or more types can be used in combination.

[0031] As for cement, there are no specific limitations. Examples include various types of silicate cement such as ordinary silicate cement, early-strength silicate cement, medium-heat silicate cement, and low-heat silicate cement, as well as blended cements such as blast furnace cement and fly ash cement, and eco-friendly cement.

[0032] As an example of waste concrete shreds, one can cite the powdery material obtained by crushing concrete waste generated during the dismantling of concrete structures, removing aggregates from the crushed material, and containing cement hydrates and unhydrated cement. The CaO content of waste concrete shreds is typically 15% by mass or more.

[0033] Ready-mixed concrete sludge powder is a powdery substance containing cement hydrates and unhydrated cement hydrates, obtained by screening the sludge generated during the concrete manufacturing process at ready-mixed concrete plants and concrete product factories using sieves. The CaO content of ready-mixed concrete sludge is typically above 30% by mass.

[0034] Examples of blast furnace slag powder include water-crushed slag, obtained by rapidly cooling and crushing molten slag, a byproduct of pig iron production in a blast furnace, and slow-cooled slag, obtained by slow cooling and crushing. The CaO content of blast furnace slag powder is typically above 35% by mass.

[0035] The calcium content in the calcium-containing powder, converted to oxides (CaO), is preferably 15% by mass or more, more preferably 20% by mass or more, and particularly preferably 30% by mass or more. If the above-mentioned content is 15% by mass or more, the strength performance of the cement composition can be further improved when the obtained carbonated slurry is used as part of a cement composition such as concrete. The upper limit of the above-mentioned content is not particularly limited, and is generally 90% by mass.

[0036] As water, there are no specific limitations; examples include sewer water, industrial water, supernatant water generated in concrete manufacturing plants, and recycled water such as sludge water.

[0037] The water-to-calcium powder ratio (mass ratio of water to calcium powder (water / calcium powder)) of the slurry varies depending on the application of the carbonated slurry and the concentration of the target carbonated slurry, and is preferably 0.2 to 10.0, more preferably 0.4 to 9.5, even more preferably more than 0.6 and less than 9.0, even more preferably 1.0 to 8.5, even more preferably 2.0 to 8.0, and particularly preferably 3.0 to 7.5.

[0038] If the water-to-calcium powder ratio is 0.2 or higher, the viscosity of the slurry decreases, thus improving workability and enabling continuous and stable absorption and immobilization of carbon dioxide in the slurry.

[0039] If the calcium powder content in the water is 10.0 or less, the application of the carbonated slurry is less limited, and when the carbonated slurry is mixed as part of materials such as concrete, it becomes easier to adjust the amount of other materials (such as water). In addition, it is possible to prevent the equipment from becoming too large.

[0040] Calcium powder and water are mixed in a mixing tank (not shown) for mixing calcium powder and water to obtain a slurry, for example, by stirring and mixing using a mixing unit such as a stirring blade or a manual mixer provided in the mixing tank. The prepared slurry is continuously supplied from the slurry supply devices 3 and 23 to the slurry tanks 2 and 22 through the slurry inflow paths 13 and 33.

[0041] For purposes such as further improving the efficiency of carbonation, a dispersion plate or nozzle may be provided in at least one of the slurry inflow paths 13 and 33 and the slurry supply area of ​​slurry tanks 2 and 22.

[0042] In addition, to prevent the calcium-containing powder in the slurry from settling in the slurry tank, slurry tanks 2 and 22 are equipped with stirring units 19 and 39. Examples of stirring units include stirring blades and manual mixers installed in the slurry tank.

[0043] In addition, to prevent the calcium-containing powder contained in the slurry from settling in the slurry tank, the slurry tanks 2 and 22 have a tapered shape that tapers toward the carbonated slurry discharge path 15 and 35 (usually located in the vertical direction below the slurry tanks 2 and 22).

[0044] It should be noted that the mixing unit can be omitted. Additionally, the shape of the slurry tank is not particularly limited.

[0045] The slurry tanks 2 and 22 have: first slurry containing portions 10a, 10b, 30a, and 30b, which contain slurry (including slurry partially carbonated during the carbonation process) and carbon dioxide-containing gas contained in the slurry tanks 2 and 22 such that gas phases 9a, 9b, 29a, and 29b, which are composed of carbon dioxide-containing gas, are located above the first liquid surfaces 8a, 8b, 28a, and 28b of the slurry, so that the slurry comes into contact with the carbon dioxide-containing gas; and a second slurry containing portion 12a, 12b, 12c, and 32 (which, unlike the gas phases composed of carbon dioxide-containing gas, are typically composed of air) such that gas phases 12a, 12b, 12c, and 32 are located above the second liquid surfaces 11a, 11b, 11c, and 31 of the slurry, and do not have a contact surface between the slurry and the carbon dioxide-containing gas.

[0046] The number of first slurry-containing portions in slurry tanks 2 and 22 shall be at least one, or more than two.

[0047] The first slurry container can be located inside the slurry tank or outside the slurry tank.

[0048] For example, in Figure 1In the first slurry receiving portion 10a, 10b, at least a portion of the first slurry receiving portion is submerged in the slurry 18 contained in the slurry tank 2. The first slurry receiving portion 10a, 10b can be fixed to the cover portion of the slurry tank 2, or it can be fixed to the inner wall portion of the slurry tank 2 using a portion of the first slurry receiving portion or using a fixing member (not shown).

[0049] The gas phases 12a, 12b, and 12c are continuous spaces. In addition, the second liquid surfaces 11a, 11b, and 11c are liquid surfaces other than the first liquid surfaces 8a and 8b of the slurry 18, and the second liquid surfaces 11a, 11b, and 11c have the same height.

[0050] The slurry contained in the first slurry containing portions 10a and 10b is contained in the first slurry containing portions 10a and 10b through an outflow inlet. The outflow inlet is located at the end of the first slurry containing portions 10a and 10b below the vertical direction and at a position below the liquid surface (second liquid surface) of the slurry 18 contained in the slurry tank 2 (excluding the slurry contained in the first slurry containing portions 10a and 10b) in the vertical direction.

[0051] exist Figure 2 In this process, the first slurry receiving portions 30a and 30b are disposed on the outer wall portion of the slurry tank 22. The first slurry receiving portions 30a and 30b may also form a region of the outer wall of the slurry tank.

[0052] The slurry contained in the first slurry containing portions 30a and 30b is contained in the first slurry containing portions 30a and 30b through outflow inlets 40a and 40b. The outflow inlets 40a and 40b are located at the ends of the first slurry containing portions 30a and 30b in the vertical direction and are located at a position that is lower in the vertical direction than the liquid surface (second liquid surface) of the slurry 38 contained in the slurry tank 22 (excluding the slurry contained in the first slurry containing portions 30a and 30b).

[0053] exist Figure 2 In the middle, the first slurry receiving parts 30a and 30b and the slurry tank 22 are connected at the outflow and inflow inlets 40a and 40b.

[0054] When the first slurry container is disposed outside the slurry tank, an outflow / inflow path may also be provided, connecting the outflow / inflow inlet of the first slurry container to the outflow / inflow inlet of the slurry tank. The outflow / inflow inlet of the slurry tank is usually disposed on the outer wall of the slurry tank at a position vertically below the liquid surface (second liquid surface) of the slurry contained in the slurry tank.

[0055] A portion of the slurry contained in the slurry tank is contained in the first slurry containing section through the outflow inlet.

[0056] In the first slurry container, by contacting the slurry with the carbon dioxide-containing gas (at the interface between the liquid surface and the gas phase) in an environment where the pressure of the gas phase consisting of carbon dioxide gas is greater than atmospheric pressure (for example, as a pressure difference of 0.02 MPa or more), carbon dioxide can be efficiently and more abundantly absorbed and immobilized in the slurry.

[0057] It should be noted that the first slurry container is typically a container with a pressurization structure. Under pressure (making the internal pressure of the first slurry container greater than atmospheric pressure), carbon dioxide gas is supplied to the gas phase of the first slurry container, thereby increasing the amount of carbon dioxide immobilized in the carbonated slurry, and thus obtaining a carbonated slurry with more immobilized carbon dioxide.

[0058] In addition, from the viewpoint of efficiently and more effectively absorbing and immobilizing carbon dioxide in the slurry, a stirring unit such as stirring blades can be provided in the first slurry container. The slurry can be stirred using the stirring unit, or the slurry can be circulated using a circulation unit, so that the slurry comes into contact with the carbon dioxide-containing gas.

[0059] Carbon dioxide-containing gas is supplied from carbon dioxide-containing gas supply devices 4 and 24 through carbon dioxide-containing gas inflow paths 14 and 34 at a pressure greater than atmospheric pressure to the gas phases 9a, 9b, 29a, and 29b of the first slurry receiving sections 10a, 10b, 30a, and 30b, which are composed of carbon dioxide-containing gas.

[0060] From the viewpoint of preventing blockage caused by the formation of scale, the inlets of carbon dioxide-containing gas in the first slurry containment sections 10a, 10b, 30a, and 30b are usually located in a position that does not come into contact with the slurry (the upper part of the first slurry containment section (e.g., the cover) is located vertically above the first liquid surface).

[0061] As a gas containing carbon dioxide, it can be a gas composed solely of carbon dioxide (carbonic acid gas), but from the viewpoint of ease of acquisition, it can also be a gas containing carbon dioxide.

[0062] The proportion of carbon dioxide in the carbon dioxide-containing gas is preferably 5% by volume or more, more preferably 10% by volume or more, even more preferably 20% by volume or more, even more preferably 50% by volume or more, even more preferably 80% by volume or more, and particularly preferably 90% by volume or more. If this proportion is 5% by volume or more, the amount of carbon dioxide immobilized in the slurry can be further increased. In addition, the time required to prepare the carbonated slurry can be further shortened.

[0063] Examples of carbon dioxide-containing gases include liquefied carbon dioxide, waste gas generated in cement manufacturing processes (carbon dioxide concentration: approximately 20% by volume), waste gas generated in ironmaking processes (carbon dioxide concentration: approximately 20% by volume), waste gas generated in thermal power generation processes (carbon dioxide concentration: approximately 10% by volume), or separated and recovered gases from these waste gases (carbon dioxide concentration: approximately 100% by volume).

[0064] The pressure difference between the gas phase supplying carbon dioxide-containing gas (the gas phase consisting of carbon dioxide-containing gas in the first slurry container) and atmospheric pressure is preferably 0.02 to 0.2 MPa, more preferably 0.03 to 0.18 MPa, and particularly preferably 0.04 to 0.15 MPa. If the pressure is 0.02 MPa or higher, the amount of carbon dioxide immobilized in the slurry per unit time can be further increased, enabling more efficient carbonation of the slurry. Furthermore, it allows for smaller carbonation tanks and other equipment. If the pressure is 0.2 MPa or lower, excessive equipment costs can be prevented.

[0065] The carbonized slurry in the first slurry container moves from the first slurry container through the outflow inlet to the liquid phase composed of slurry (excluding the slurry contained in the first slurry container) in the slurry tank.

[0066] In this specification, the term "liquid phase" has the concept of a slurry consisting of a mixture of liquid and powder (specifically, water and calcium-containing powder).

[0067] The inlet and outlet of the first slurry container only need to allow the slurry to move inside and outside the first slurry container. There can be one inlet or two outlets: one for allowing the slurry to flow into the first slurry container and the other for allowing the slurry to flow out of the first slurry container.

[0068] Carbonated slurry discharge devices 5 and 25 are used to continuously discharge slurries containing sufficiently immobilized carbon dioxide in the first slurry receiving sections 10a, 10b, 30a, and 30b as carbonated slurries (carbonated slurries that have absorbed and immobilized a target amount of carbon dioxide) from slurry tanks 2 and 22. The carbonated slurry is discharged from slurry tanks 2 and 22 through carbonated slurry discharge paths 15, 17, 35, and 37.

[0069] The discharged carbonated slurry can be used as a material in cementitious compositions such as concrete.

[0070] Liquid level measuring units 6a, 6b, 26a, and 26b are used to measure the heights of the first liquid levels 8a, 8b, 28a, and 28b in the first slurry containing portions 10a, 10b, 30a, and 30b, respectively.

[0071] In addition, liquid level measuring units 6c and 26c are used to measure the height of the second liquid level 11b and 31 in the second slurry containing part of the slurry tank 2 and 32, respectively.

[0072] It should be noted that the second slurry receiving portion refers to the part of the slurry tank that contains slurry other than that contained in the first slurry receiving portion. In addition, the second liquid level refers to the liquid level of the liquid phase composed of slurry (excluding the slurry contained in the first slurry receiving portion) within the slurry tank.

[0073] The pressure of the gas phase consisting of carbon dioxide in the first slurry container is greater than the pressure of the gas phase in the second slurry container. Therefore, the height of the first liquid level is usually located at a position lower in the vertical direction than the height of the second liquid level.

[0074] In cases where the slurry tank has two or more first slurry holding sections and carbon dioxide gas is supplied to the two or more first slurry holding sections using a carbon dioxide gas inflow path branching from a carbon dioxide gas inflow path, and the pressure of the gas phase composed of carbon dioxide gas in the two or more first slurry holding sections can be controlled simultaneously, the height of the first liquid level can also be measured by using a liquid level measuring unit for only one of the two or more first slurry holding sections.

[0075] The slurry control devices 7 and 27 are used to adjust the amount of slurry supplied per unit time from the slurry supply devices 3 and 23 and the amount of carbonated slurry discharged per unit time from the carbonated slurry discharge devices 5 and 25 based on the heights (the height of the first liquid level and the height of the second liquid level) measured by the liquid level measuring units 6a, 6b, 6c, 26a, 26b, and 26c, and to control the average residence time of the slurry from supply to discharge (the average time required from the time the slurry is supplied until it is discharged as carbonated slurry).

[0076] When carbonation of slurry is carried out continuously under pressure, the quality of the resulting carbonated slurry (e.g., the degree of carbonation) is affected by factors such as the average residence time of the carbonated slurry and the pressure of the gas phase composed of carbon dioxide-containing gas. Therefore, it is difficult to control the average residence time of the carbonated slurry to a constant value and to maintain the quality of the carbonated slurry stably. However, according to the present invention, by adjusting the supply rate of slurry per unit time and the discharge rate of carbonated slurry per unit time based on the height measured by the liquid level measuring unit, it is easier and more stable to control the average residence time of the slurry, and to continuously produce fully carbonated slurry.

[0077] More specifically, based on the capacity of the slurry tank (the first slurry container and the second slurry container) and the measurement results obtained from the liquid level measuring unit, the total amount of slurry in the slurry tank is calculated. The supply rate of slurry per unit time and the discharge rate of carbonated slurry per unit time are adjusted to keep the total amount of slurry constant. This allows the average residence time of the slurry to be stabilized, and fully carbonated slurry to be produced continuously.

[0078] In addition to adjusting the amount of slurry supplied per unit time from the slurry supply device and the amount of carbonated slurry discharged per unit time from the carbonated slurry discharge device, the slurry control device can also adjust the supply amount of carbon dioxide-containing gas from the carbon dioxide-containing gas supply device (in other words, by increasing or decreasing the supply amount, the pressure of the gas phase composed of carbon dioxide-containing gas in the first slurry receiving unit is adjusted).

[0079] The carbonated slurry manufacturing systems 1 and 21 have slurry circulation paths 16 and 36 for returning at least a portion of the carbonated slurry discharged from the slurry tanks 2 and 22 to the slurry tanks 2 and 22 for circulation.

[0080] It should be noted that the slurry circulation path can be omitted.

[0081] In addition, to facilitate the circulation of the carbonated slurry, circulation units such as circulation pumps can be installed in slurry circulation paths 16 and 36. Here, the carbonated slurry discharge devices 5 and 25 can also serve as circulation units. Furthermore, for the purpose of further improving the efficiency of carbonated slurry, a dispersion disc or nozzle (not shown) can be installed in at least one of the areas from which slurry is supplied from slurry circulation paths 16 and 36.

[0082] The above cycle is usually continued until the slurry becomes a carbonated slurry that has absorbed and immobilized the target amount of carbon dioxide (a carbonated slurry that has absorbed and immobilized a sufficient amount of carbon dioxide gas).

[0083] By circulating the carbonated slurry while performing carbonation, the amount of carbon dioxide immobilized in the slurry per unit time can be further increased, enabling more efficient slurry carbonation. Furthermore, even when carbonation is performed continuously, the required carbonation time can be easily adjusted.

[0084] From the perspective of further improving the efficiency of carbonation, the carbonated slurry circulated from the circulating pump can be sent back to the first slurry receiving unit.

[0085] The carbonated slurry manufacturing system may include a liquid temperature adjustment unit (not shown) for adjusting the liquid temperature of the carbonated slurry.

[0086] The degree of carbon dioxide absorption and immobilization in the slurry, as well as the properties of the carbonated slurry (e.g., viscosity, particle size of the calcium-containing powder contained in the carbonated slurry), are affected by the temperature of the carbonated slurry (comprising at least a portion of the carbonated slurry contained in a slurry tank). By adjusting the liquid temperature of the carbonated slurry, carbon dioxide can be absorbed and immobilized in the slurry more efficiently and in larger quantities, and the properties of the carbonated slurry can be more easily managed (adjusted).

[0087] The liquid temperature adjustment unit only needs to have a cooling unit and a heating unit; there are no particular limitations. The liquid temperature adjustment unit can be installed in the slurry tank, slurry circulation path, etc.

[0088] The liquid temperature adjustment unit adjusts the liquid temperature of the carbonated slurry based on the liquid temperature measured by a temperature measuring unit (not shown) used to measure the liquid temperature of the carbonated slurry. The temperature measuring unit can be appropriately installed in the slurry tank, slurry circulation path, etc.

[0089] The liquid temperature of the carbonated slurry, adjusted by the liquid temperature adjustment unit, is preferably 10–50°C, more preferably 20–40°C. If the liquid temperature is 10°C or higher, the cost of the cooling equipment can be prevented from becoming too high. If the liquid temperature is 50°C or lower, carbon dioxide can be absorbed and immobilized in the slurry more efficiently and in larger quantities.

[0090] In addition, for the purpose of adjusting the temperature of the slurry supplied to the slurry tank, a liquid temperature adjustment unit and a liquid temperature measuring unit may be installed in the mixing tank (not shown).

[0091] A carbonated cement slurry manufacturing system may include a pH measuring unit (not shown) for determining the pH of the carbonated slurry (comprising at least a portion of the carbonated slurry contained in a slurry tank). Based on the measured pH value of the carbonated slurry, it is possible to determine whether a carbonated slurry containing a target amount of carbon dioxide has been obtained (whether a sufficient amount of carbon dioxide gas has been absorbed and immobilized in the slurry).

[0092] For example, if the pH value of the carbonated slurry (at least a portion of the carbonated slurry contained in the slurry tank) is within a predetermined range, it can be determined that the carbonated slurry has absorbed and immobilized a sufficient amount of carbon dioxide gas, and the carbonated slurry in the slurry tank can be discharged as carbonated slurry that has absorbed and immobilized a target amount of carbon dioxide (carbon dioxide gas).

[0093] Furthermore, based on the pH value of the carbonated slurry, adjustments can be made to the supply of carbon dioxide-containing gas from the carbon dioxide-containing gas supply device (in other words, by increasing or decreasing the supply, the pressure of the gas phase composed of carbon dioxide-containing gas in the first slurry containing unit is adjusted), and the circulation of the slurry is adjusted, thereby enabling the management (adjustment) of the preparation of the carbonated slurry.

[0094] Furthermore, regarding the aforementioned slurry control device, the amount of slurry supplied per unit time from the slurry supply device and the amount of carbonated slurry discharged per unit time from the carbonated slurry discharge device can be adjusted based on the height (the height of the first liquid level and the height of the second liquid level) measured by the liquid level measuring unit and the pH of the carbonated slurry measured by the pH measuring unit.

[0095] pH measuring units can be installed in components such as slurry tanks and slurry circulation paths that store or transport carbonated slurries.

[0096] Furthermore, for the purpose of managing the preparation of carbonated slurry, each component constituting the above-mentioned carbonated slurry manufacturing system may be equipped with various measuring units such as thermometers for measuring the temperature of the gas phase in the slurry tank, carbonate ion concentration measuring devices, oxygen concentration measuring devices, carbon dioxide concentration measuring devices, and pressure gauges.

[0097] In addition, these measurement results can also be used for control based on slurry control devices.

[0098] As an example of a method for manufacturing a carbonated slurry by carbonated slurry containing calcium powder and water using the aforementioned carbonated slurry manufacturing system, the following carbonated slurry manufacturing method can be cited, which includes: a slurry preparation step, in which calcium powder is mixed with water to obtain a slurry; a slurry supply step, in which the slurry is continuously supplied to a slurry tank for containing the slurry; and a slurry containing step, in which the slurry and the carbon dioxide-containing gas are contained in a first slurry containing portion of the slurry tank such that the gas phase of the carbon dioxide-containing gas is located above a first liquid surface of the slurry, and in a manner such that the gas phase is located above a second liquid surface of the slurry and there is no contact surface between the slurry and the carbon dioxide-containing gas. The process includes: a second slurry receiving section housed in a slurry tank; a carbonic acid slurry preparation step, in which carbon dioxide-containing gas is supplied to the first slurry receiving section at a pressure greater than atmospheric pressure, causing the first liquid surface to contact the gas phase, thereby carbonizing the slurry and obtaining a carbonic acid slurry; a carbonic acid slurry discharge step, in which the carbonic acid slurry is continuously discharged from the slurry tank; and a liquid level measurement step, in which the height of the first liquid level in the first slurry receiving section and the height of the second liquid level in the second slurry receiving section are measured, and based on the measurement results obtained in the liquid level measurement step, the amount of slurry supplied per unit time in the slurry supply step and the amount of carbonic acid slurry discharged per unit time in the carbonic acid slurry discharge step are adjusted.

[0099] Symbol Explanation

[0100] 1.21 Carbonated Slurry Manufacturing System

[0101] 2.22 Slurry Tank

[0102] 3.23 Slurry supply device

[0103] 4.24 Carbon dioxide gas supply device

[0104] 5.25 Carbonated slurry discharge device

[0105] Liquid level measurement units 6a, 6b, 6c, 26a, 26b, 26c

[0106] 7.27 Slurry Control Device

[0107] 8a, 8b, 28a, 28b First liquid level

[0108] 9a, 9b, 29a, and 29b are gas phases composed of carbon dioxide.

[0109] 10a, 10b, 30a, 30b First slurry container section

[0110] 11a, 11b, 11c, 31 Second Liquid Surface

[0111] 12a, 12b, 12c, 32 gas phase

[0112] 13, 33 Slurry Inflow Path

[0113] 14, 34 Carbon dioxide-containing gas inflow path

[0114] 15, 17, 35, 37 Carbonated slurry discharge routes

[0115] 16, 36 slurry circulation path

[0116] 18 and 38 slurries (including partially carbonated slurries)

[0117] 19 and 39 mixing units

[0118] 40a, 40b outflow inflow

Claims

1. A carbonation slurry manufacturing system, which is used to manufacture carbonation slurry, wherein the carbonation slurry is formed by carbonating a slurry containing calcium powder and water using a gas containing carbon dioxide, and the carbonation slurry manufacturing system is characterized in that it comprises: A slurry tank, used for containing the slurry; A slurry supply device, used for continuously supplying the slurry to the slurry tank; A gas supply device containing carbon dioxide, used for supplying the gas containing carbon dioxide; a carbonated slurry discharge device, used for continuously discharging the carbonated slurry from the slurry tank; a liquid level measuring unit, which is used to measure the height of the liquid level composed of slurry in the slurry tank; and a slurry control device for controlling the average residence time of the slurry, The slurry tank comprises: a first slurry containing part for containing the slurry and the gas containing carbon dioxide in a manner that a gas phase composed of the gas containing carbon dioxide is located above a first liquid level of the slurry, so that the slurry is in contact with the gas containing carbon dioxide; and a second slurry containing part for containing the slurry in a manner that a gas phase is located above a second liquid level of the slurry and does not have a contact surface between the slurry and the gas containing carbon dioxide. The carbon dioxide-containing gas supply device supplies the carbon dioxide-containing gas to the gas phase composed of the carbon dioxide-containing gas in the first slurry holding portion at a pressure greater than atmospheric pressure, The liquid level measuring unit measures the height of a first liquid level of the first slurry containing part and a second liquid level of the second slurry containing part, respectively. The slurry control device adjusts the amount of the slurry supplied per unit time from the slurry supply device and the amount of the carbonated slurry discharged per unit time from the carbonated slurry discharge device based on the respective heights of the first liquid level of the first slurry holding part and the second liquid level of the second slurry holding part measured by the liquid level measuring unit, thereby controlling the average residence time of the slurry.

2. The carbonation slurry production system according to claim 1, wherein: The carbonated slurry production system includes a slurry circulation path for returning at least a portion of the carbonated slurry discharged from the slurry tank to the slurry tank for circulation.

3. The carbonation slurry production system according to claim 1 or 2, wherein: The slurry tank includes a stirring unit for stirring and mixing the carbonated slurry in the slurry tank.

4. The carbonation slurry production system according to claim 1 or 2, wherein: The carbonated slurry production system includes a pH measuring unit for measuring the pH of the carbonated slurry.

5. The carbonation slurry production system according to claim 1 or 2, wherein: The carbonated slurry production system includes a liquid temperature adjustment unit for adjusting the liquid temperature of the carbonated slurry.

6. A method for producing a carbonated slurry, which is a method for producing a carbonated slurry, wherein the carbonated slurry is formed by carbonating a slurry containing calcium powder and water using a gas containing carbon dioxide, and the method for producing a carbonated slurry is characterized in that it comprises: a slurry preparation step of mixing the calcium-containing powder with the water to obtain the slurry; A slurry supplying step of continuously supplying the slurry to a slurry tank for containing the slurry; A slurry containing step of containing the slurry and the gas containing carbon dioxide in a first slurry containing part of the slurry tank in such a manner that a gas phase composed of the gas containing carbon dioxide is located above a first liquid level of the slurry, and containing the slurry and the gas containing carbon dioxide in a second slurry containing part of the slurry tank in such a manner that a gas phase is located above a second liquid level of the slurry and there is no contact surface between the slurry and the gas containing carbon dioxide; a step of preparing a carbonated slurry, supplying the gas containing carbon dioxide to the gas phase consisting of the gas containing carbon dioxide in the first slurry containing portion at a pressure greater than atmospheric pressure, so that the first liquid surface contacts the gas phase, thereby carbonates the slurry to obtain a carbonated slurry; a carbonated slurry discharging step of continuously discharging the carbonated slurry from the slurry tank; and a liquid level measuring step of measuring the height of the first liquid level of the first slurry containing part and the height of the second liquid level of the second slurry containing part, Based on the measurement result obtained in the liquid level measuring step, the supply amount of the slurry per unit time in the slurry supplying step and the discharge amount of the carbonated slurry per unit time in the carbonated slurry discharging step are adjusted.

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