Carbonated slurry manufacturing system

Abstract

The present invention provides a carbonation slurry production system, which can fix carbon dioxide in a slurry composed of calcium-containing powder and water and can easily control the average residence time of the slurry. A carbonated slurry manufacturing system (1) comprises: a slurry tank (2) having a first slurry containing portion (10a), (10b) for contacting the slurry with a carbon dioxide-containing gas; a slurry supply device (7) for supplying a slurry consisting of calcium-containing powder and water; a carbon dioxide-containing gas supply device (4) for supplying a carbon dioxide-containing gas to a gas phase (9a), (9b) consisting of the carbon dioxide-containing gas in the first slurry containing portion at a pressure greater than atmospheric pressure; a carbonated slurry discharge device (5) for discharging the carbonated slurry; liquid level measuring units (6a), (6b), (6c) for measuring the height of the liquid level consisting of the slurry; and a slurry control device (7) for controlling the average residence time of the slurry based on the respective heights of the first liquid level (8a), (8b) and the second liquid level (11).

Description

Technical Field

[0001] The present invention relates to a carbonation slurry manufacturing system. Background Art

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

[0003] In connection with this, a technology for fixing carbon dioxide recovered from exhaust gas generated in cement manufacturing plants and the like in concrete and the like has been studied.

[0004] On the other hand, from the perspective of resource and environmental protection, incineration ash generated when incinerating general waste, industrial waste, and other municipal waste, and calcium-containing powders such as clinker dust generated in cement plants are effectively reused as cement raw materials.

[0005] As a method for removing chlorine contained in incineration ash, clinker dust, etc. in order to appropriately utilize the incineration ash, clinker dust, etc. as cement raw materials, Patent Document 1 describes a method for treating chlorine-containing ash, which is characterized in that it comprises: a washing step, in which water is added to the chlorine-containing ash and the chlorine-containing ash is stirred and washed; a ash slurry concentration step, in which a polymer coagulant is added to the ash slurry obtained through the washing step and sedimentation separation is performed; a first dehydration step, in which the concentrated ash slurry discharged from the concentration step is dehydrated using a vacuum belt filter; a high-desalination step, in which the dehydrated filter cake of the ash discharged from the dehydration step is dispersed with water and a gas containing carbon dioxide is added, while heating; and a second dehydration step, in which the slurry obtained through the high-desalination step is dehydrated using a filter press to prepare a washed ash filter cake.

[0006] In addition, as can effectively make slaked lime contact with carbon dioxide, well control, promote the method for carbonation reaction, a kind of manufacture method of calcium carbonate is put down in writing among the patent documentation 2, it comprises that the liquid that will contain calcium hydroxide and auxiliary agent mixes and supplies to reactive tank with the waste gas that contains carbon dioxide by ejector, wherein, as the liquid that contains calcium hydroxide, use the reaction solution from reactive tank circulation.

[0007] Prior art literature

[0008] Patent Literature

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

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

[0011] Problems to be solved by the invention

[0012] The object of the present invention is to provide a carbonated slurry manufacturing system, which can continuously and efficiently fix carbon dioxide in a slurry composed of calcium-containing powder and water, and can easily and stably control the average residence time of the slurry (the average time from the supply of the slurry to the discharge as carbonated slurry).

[0013] Means for solving problems

[0014] The inventors conducted in-depth research to solve the above-mentioned problems and found that the above-mentioned purpose can be achieved according to the following carbonated slurry manufacturing system, thereby completing the present invention, which includes: a slurry tank for accommodating 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 level composed of 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 respective heights of the first liquid level and the second liquid level 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 carbonated slurry, wherein the carbonated slurry is formed by carbonated slurry containing calcium powder and water using a gas containing carbon dioxide, and the carbonated slurry manufacturing system is characterized in that it includes: a slurry tank for accommodating 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 composed of 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 holding portion for accommodating the slurry and the carbon dioxide-containing gas in a manner that the gas phase composed of the carbon dioxide-containing gas is located above the first liquid level of the slurry, so that the slurry contact with the above-mentioned carbon dioxide-containing gas; and a second slurry holding part, which holds the slurry in a manner such that the gas phase is located above the second liquid level of the slurry and does not have a contact surface between the slurry and the above-mentioned carbon dioxide-containing gas, the above-mentioned carbon dioxide-containing gas supply device supplies the above-mentioned carbon dioxide-containing gas to the gas phase composed of the above-mentioned carbon dioxide-containing gas in the above-mentioned first slurry holding part at a pressure greater than atmospheric pressure, the above-mentioned liquid level measuring unit measures the respective heights of the first liquid level of the above-mentioned first slurry holding part and the second liquid level of the above-mentioned second slurry holding part, the above-mentioned slurry control device adjusts the amount of the above-mentioned slurry supplied per unit time from the above-mentioned slurry supply device and the amount of the above-mentioned carbonated slurry discharged per unit time from the above-mentioned carbonated slurry discharge device based on the respective heights of the first liquid level of the above-mentioned first slurry holding part and the second liquid level of the above-mentioned second slurry holding part measured by the above-mentioned liquid level measuring unit, and controls the average residence time of the above-mentioned slurry.

[0017] [2] The carbonated slurry production system as described in [1] above, 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.

[0018] [3] The carbonated slurry production system according to [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 production system according to any one of [1] to [3] above, wherein the carbonated slurry production system includes a pH measuring unit for measuring the pH of the carbonated slurry.

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

[0021] [6] A method for producing a carbonated slurry, which is a method for producing a carbonated slurry, wherein the carbonated slurry is obtained by carbonated a slurry containing calcium powder and water using a gas containing carbon dioxide, and the carbonated slurry production method is 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 gas containing carbon dioxide are contained in a first slurry containing part of the slurry tank in a manner that a gas phase composed of the gas containing carbon dioxide is located above a first liquid level of the slurry, and in a manner that the 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; a second slurry holding part of the slurry tank; a carbonated slurry preparation process, supplying the carbon dioxide-containing gas to the gas phase composed of the carbon dioxide-containing gas in the first slurry holding part at a pressure greater than atmospheric pressure, so that the first liquid surface contacts the gas phase, thereby carbonates the slurry to obtain carbonated slurry; a carbonated slurry discharge process, continuously discharging the carbonated slurry from the slurry tank; and a liquid level measuring process, measuring the heights of the first liquid surface of the first slurry holding part and the second liquid surface of the second slurry holding part, and adjusting the supply amount of the slurry per unit time in the slurry supply process and the discharge amount of the carbonated slurry per unit time in the carbonated slurry discharge process based on the measurement results obtained in the liquid level measuring process.

[0022] Effects of the Invention

[0023] According to the carbonated slurry production system of the present invention, carbon dioxide can be continuously and efficiently fixed in a slurry containing calcium powder and water, and the average residence time of the slurry (the average time from the supply of the slurry to the discharge as carbonated slurry) can be easily and stably controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a diagram schematically showing an example of the carbonation slurry production system of the present invention.

[0025] Figure 2 This is a diagram schematically showing an example of the carbonation slurry production system of the present invention. DETAILED DESCRIPTION

[0026] The carbonated slurry manufacturing system of the present invention is a carbonated slurry manufacturing system for manufacturing carbonated slurry formed by carbonating a slurry containing calcium powder and water using a gas containing carbon dioxide. 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 gas supply device containing carbon dioxide for supplying gas containing carbon dioxide; 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 composed of slurry in the slurry tank; and a slurry control device for controlling the average residence time of the slurry. The above-mentioned slurry tank has: a first slurry holding portion for holding slurry and gas containing carbon dioxide in a manner that a gas phase composed of gas containing carbon dioxide is located above the first liquid level of the slurry, so that the slurry is in contact with the gas containing carbon dioxide; and a second slurry holding portion for holding slurry in a manner that a gas phase is located above the 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 carbon dioxide-containing gas at a pressure greater than atmospheric pressure to the gas phase composed of carbon dioxide-containing gas in the first slurry storage portion. The liquid level measuring unit measures the height of the first liquid level in the first slurry storage portion and the second liquid level in the second slurry storage portion. The 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 based on the heights of the first liquid level in the first slurry storage portion and the second liquid level in the second slurry storage portion, thereby controlling the average residence time of the slurry.

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

[0028] Below, refer to Figures 1-2 The carbonated slurry production systems 1 and 21 of the present invention will be described in detail.

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

[0030] The calcium-containing powder is not particularly limited as long as it is a powder containing calcium, and examples thereof include cement, crushed waste concrete, ready-mixed concrete sludge powder, blast furnace slag powder, municipal waste incineration ash (fly ash, main ash), and cement kiln dust. These can be used alone or in combination of two or more.

[0031] Cement is not particularly limited, and examples thereof include various Portland cements such as ordinary Portland cement, early-strength Portland cement, moderate-heat Portland cement, and low-heat Portland cement; blended cements such as blast furnace cement and fly ash cement; and ecological cement.

[0032] Examples of crushed waste concrete include crushed concrete waste generated during the dismantling of concrete structures, etc., and then removing aggregate from the crushed concrete to obtain a powdery product containing cement hydrate and cement unhydrate. The CaO content of the crushed waste concrete is generally 15% by mass or greater.

[0033] Ready-mix concrete sludge powder is a powdery substance containing cement hydrate and unhydrated cement, obtained by sieving sludge generated during the concrete production process at a ready-mix concrete plant or concrete product factory using a sieve or other method. The CaO content of the ready-mix concrete sludge is typically 30% by mass or higher.

[0034] Examples of blast furnace slag powder include granulated slag obtained by rapidly cooling and crushing molten slag produced as a by-product during pig iron production in a blast furnace, and slowly cooled slag obtained by slowly cooling and crushing. The CaO content of the blast furnace slag powder is generally 35% by mass or greater.

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

[0036] The water is not particularly limited, and examples thereof include sewage water, industrial water, supernatant water generated in a concrete production plant, recovered water such as sludge water, and the like.

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

[0038] When the water-calcium powder ratio is 0.2 or more, the viscosity of the slurry decreases, thereby improving workability and enabling continuous and stable absorption and fixation of carbon dioxide in the slurry.

[0039] If the water-to-calcium powder ratio is 10.0 or less, the use of the carbonated slurry is less likely to be limited, and when the carbonated slurry is mixed as part of a material such as concrete, it becomes easier to adjust the amount of other materials (such as water). In addition, it can prevent the device from becoming too large.

[0040] The calcium-containing powder and water are stirred and mixed in a mixing tank (not shown) for mixing the calcium-containing powder and water to obtain a slurry, using a mixing unit such as a stirring blade or a hand mixer provided in the mixing tank to prepare a slurry. The prepared slurry is continuously supplied from the slurry supply device 3, 23 to the slurry tank 2, 22 through the slurry inlet path 13, 33.

[0041] For the purpose of further improving the carbonation efficiency, a dispersion plate or a nozzle may be provided in at least one of the slurry inflow passages 13 and 33 and the slurry supply region of the slurry tanks 2 and 22 .

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

[0043] Furthermore, in order to prevent calcium powder contained in the slurry from settling in the slurry tank, the slurry tanks 2 and 22 have a tapered shape toward the carbonated slurry discharge path 15 and 35 (generally provided at the vertically lower portion of the slurry tanks 2 and 22 ).

[0044] It should be noted that the stirring unit may be omitted. In addition, the shape of the slurry tank is not particularly limited.

[0045] The slurry tanks 2, 22 have: a first slurry holding portion 10a, 10b, 30a, 30b, which is used to hold the slurry (including the slurry part of which is carbonated during the carbonation process of the slurry) and the gas containing carbon dioxide held in the slurry tanks 2, 22 in a manner such that the gas phase 9a, 9b, 29a, 29b composed of the gas containing carbon dioxide is located above the first liquid level 8a, 8b, 28a, 28b of the slurry, so that the slurry is in contact with the gas containing carbon dioxide; and a second slurry holding portion, which holds the slurry in a manner such that the gas phase 12a, 12b, 12c, 32 (which is different from the above-mentioned gas phase composed of the gas containing carbon dioxide and is usually a gas phase composed of air) is located above the second liquid level 11a, 11b, 11c, 31 of the slurry, and does not have a contact surface between the slurry and the gas containing carbon dioxide.

[0046] The number of the first slurry containing parts included in the slurry tanks 2 and 22 may be at least one, and may be two or more.

[0047] The first slurry containing portion may be disposed inside the slurry tank or outside the slurry tank.

[0048] For example, in Figure 1In the embodiment, the first slurry containing parts 10a and 10b are arranged so that at least a portion of the first slurry containing parts is immersed in the slurry 18 contained in the slurry tank 2. The first slurry containing parts 10a and 10b can be fixed to the cover of the slurry tank 2, or can be fixed to the inner wall of the slurry tank 2 using a portion of the first slurry containing parts or using a fixing member (not shown).

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

[0050] The slurry contained in the first slurry containing parts 10a, 10b is contained in the first slurry containing parts 10a, 10b through the outflow inlet, which is opened at the end portion below the first slurry containing parts 10a, 10b in the vertical direction and at a position vertically below the liquid level (second liquid level) of the slurry 18 contained in the slurry tank 2 (excluding the slurry contained in the first slurry containing parts 10a, 10b).

[0051] exist Figure 2 In the embodiment, the first slurry receiving portions 30a and 30b are provided 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 parts 30a, 30b is contained in the first slurry containing parts 30a, 30b through the outflow inlet 40a, 40b, which is located at the end portion below the first slurry containing parts 30a, 30b in the vertical direction and opens at a position vertically below the liquid level (second liquid level) of the slurry 38 contained in the slurry tank 22 (excluding the slurry contained in the first slurry containing parts 30a, 30b).

[0053] exist Figure 2 In the embodiment, the first slurry receiving portions 30a, 30b and the slurry tank 22 are connected at the outflow and outflow ports 40a, 40b.

[0054] When the first slurry storage portion is disposed outside the slurry tank, an inflow and outflow path may be provided that connects the inflow and outflow port of the first slurry storage portion to the inflow and outflow port of the slurry tank. The inflow and outflow port of the slurry tank is typically disposed on the outer wall of the slurry tank at a position vertically below the liquid level (second liquid level) of the slurry contained in the slurry tank.

[0055] A portion of the slurry accommodated in the slurry tank is accommodated in the first slurry accommodation portion through the outflow inlet.

[0056] In the first slurry holding portion, by bringing the slurry into contact with the carbon dioxide-containing gas (contact at the boundary surface between the liquid surface and the gas phase) in an environment where the pressure of the gas phase composed of the carbon dioxide-containing gas is greater than the atmospheric pressure (for example, the pressure difference is 0.02 MPa or more), carbon dioxide can be efficiently absorbed and fixed in the slurry in larger quantities.

[0057] It should be noted that the first slurry holding portion is typically a container having a pressurizable structure. Carbon dioxide is supplied to the gas phase of the first slurry holding portion under pressure (so that the internal pressure of the first slurry holding portion is greater than atmospheric pressure), thereby increasing the amount of carbon dioxide fixed in the carbonated slurry, thereby obtaining a carbonated slurry with more fixed carbon dioxide.

[0058] In addition, from the perspective of efficiently absorbing and fixing carbon dioxide in a larger amount in the slurry, a stirring unit such as a stirring blade can be provided in the first slurry holding portion, and the slurry can be stirred using the stirring unit, or the slurry can be circulated using a circulation unit while the slurry is brought into contact with the gas containing carbon dioxide.

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

[0060] From the perspective of preventing clogging caused by the formation of scale, the inlet for the carbon dioxide-containing gas of the first slurry holding parts 10a, 10b, 30a, 30b is usually arranged at a position that does not come into contact with the slurry (a position vertically above the first liquid surface such as the upper part of the first slurry holding part (e.g., the cover)).

[0061] The carbon dioxide-containing gas may be a gas composed only of carbon dioxide (carbonic acid gas), but may also be a gas containing carbon dioxide from the viewpoint of easy availability.

[0062] The ratio of the carbon dioxide in the carbon dioxide-containing gas is preferably more than 5 volume %, more preferably more than 10 volume %, further preferably more than 20 volume %, further preferably more than 50 volume %, further preferably more than 80 volume %, particularly preferably more than 90 volume %.If this ratio is more than 5 volume %, then can further increase the amount of the carbon dioxide that is immobilized in the slurry.In addition, can further shorten the required time of preparation carbonating slurry.

[0063] Examples of gases containing carbon dioxide include liquefied carbonic acid gas, waste gas generated in the cement manufacturing process (carbonic acid gas concentration: about 20 volume %), waste gas generated in the ironmaking process (carbonic acid gas concentration: about 20 volume %), waste gas generated in the thermal power generation process (carbonic acid gas concentration: about 10 volume %), or separated and recovered gas from these waste gases (carbonic acid gas concentration: about 100 volume %), etc.

[0064] The difference between the gas phase of the gas containing carbon dioxide (the gas phase consisting of the gas containing carbon dioxide of the first slurry accommodating part) and the 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 above-mentioned pressure is more than 0.02 MPa, the immobilization amount of carbon dioxide per unit time in the slurry can be further increased, and the slurry can be carbonated more efficiently. In addition, the carbonation tank and other devices can be made smaller. If the above-mentioned pressure is below 0.2 MPa, the cost of the equipment can be prevented from being too large.

[0065] The slurry carbonated in the first slurry storage portion moves from the first slurry storage portion through the outflow inlet to the liquid phase composed of the slurry (excluding the slurry stored in the first slurry storage portion) in the slurry tank.

[0066] In this specification, the term "liquid phase" has a concept including a slurry in which a liquid and a powder or particle (specifically, water and a calcium-containing powder) are mixed.

[0067] The inlet and outlet of the first slurry holding portion only need to be capable of moving the slurry in and out of the first slurry holding portion. The inlet and outlet may be a single inlet, or may include an inlet for allowing the slurry to flow into the first slurry holding portion and an outlet for allowing the slurry to flow out of the first slurry holding portion.

[0068] The carbonated slurry discharge device 5, 25 is a device for continuously discharging the slurry in which carbon dioxide is sufficiently fixed in the first slurry storage portion 10a, 10b, 30a, 30b as carbonated slurry (carbonated slurry that has absorbed and fixed a target amount of carbon dioxide) from the slurry tank 2, 22. The carbonated slurry is discharged from the slurry tank 2, 22 through the carbonated slurry discharge path 15, 17, 35, 37.

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

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

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

[0072] It should be noted that the second slurry holding portion refers to the portion of the slurry tank that holds slurry other than the slurry held in the first slurry holding portion. Furthermore, the second liquid level refers to the level of the liquid phase composed of slurry (excluding the slurry held in the first slurry holding portion) in the slurry tank.

[0073] Since the pressure of the gas phase composed of the carbon dioxide-containing gas in the first slurry storage part is higher than the pressure of the gas phase in the second slurry storage part, the height of the first liquid level is usually located vertically lower than the height of the second liquid level.

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

[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 control the average residence time of the slurry from supply to discharge (the average time required after the slurry is supplied to be discharged as carbonated slurry).

[0076] When the carbonation of the slurry is continuously performed under pressure, the quality of the obtained carbonated slurry (e.g., the degree of carbonation of the slurry) is affected by the average residence time of the carbonated slurry and the pressure of the gas phase composed of the gas containing carbon dioxide, etc., and it is therefore difficult to control the average residence time of the carbonated slurry to be constant, and it is difficult to stably maintain the quality of the carbonated slurry. However, according to the present invention, by adjusting the supply rate per unit time of the slurry and the discharge rate per unit time of the carbonated slurry based on the height measured by the liquid level measuring unit, etc., it is possible to more easily and stably control the average residence time of the slurry and continuously produce a fully carbonated carbonated slurry.

[0077] More specifically, the total amount of slurry in the slurry tank is calculated based on the capacity of the slurry tank (the first slurry holding part and the second slurry holding part) and the measurement results obtained by the liquid level measuring unit, and the supply amount of the slurry per unit time and the discharge amount of the carbonated slurry per unit time are adjusted to make the total amount of the slurry constant. This stabilizes the average residence time of the slurry and continuously produces fully carbonated carbonated slurry.

[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, adjusting the pressure of the gas phase composed of carbon dioxide-containing gas in the first slurry holding unit).

[0079] The carbonated slurry production systems 1 and 21 include 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 may be omitted.

[0081] In order to circulate the carbonated slurry, a circulation unit such as a circulation pump may be provided in the slurry circulation paths 16 and 36. Here, the carbonated slurry discharge devices 5 and 25 may also serve as the circulation unit. Furthermore, to further improve the efficiency of carbonation, a dispersion disk or nozzle (not shown) may be provided in at least one of the areas where the slurry is supplied from the slurry circulation paths 16 and 36.

[0082] The above-mentioned circulation is usually performed until the slurry becomes a carbonated slurry in which a target amount of carbon dioxide is absorbed and fixed (a carbonated slurry in which a sufficient amount of carbon dioxide gas is absorbed and fixed).

[0083] By circulating the carbonating slurry while carbonating the slurry, the fixed amount of carbon dioxide in the slurry per unit time can be further increased, and the slurry can be carbonated more efficiently. In addition, even when the slurry is continuously carbonated, the time required for carbonation can be easily adjusted.

[0084] From the viewpoint of further improving the efficiency of carbonation, the carbonated slurry circulated by the circulation pump may be sent back into the first slurry storage unit.

[0085] The carbonated slurry production 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 (including the slurry at least partially carbonated and contained in the slurry tank). By adjusting the liquid temperature of the carbonated slurry, carbon dioxide can be more efficiently and in larger quantities absorbed and immobilized in the slurry, and the properties of the carbonated slurry can be more easily managed (adjusted).

[0087] The liquid temperature adjustment unit is not particularly limited as long as it includes a cooling unit and a heating unit. The liquid temperature adjustment unit can be provided in a slurry tank, a slurry circulation path, or the like.

[0088] The liquid temperature adjustment unit adjusts the liquid temperature of the carbonated slurry based on the liquid temperature measured by a temperature measurement unit (not shown) for measuring the liquid temperature of the carbonated slurry. The temperature measurement unit can be appropriately provided 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. A liquid temperature of 10°C or higher can prevent excessive costs for cooling equipment. A liquid temperature of 50°C or lower allows for more efficient absorption and immobilization of carbon dioxide in the slurry.

[0090] Furthermore, in order to adjust the temperature of the slurry when it is supplied to the slurry tank, a liquid temperature adjustment unit and a liquid temperature measurement unit may be provided in the mixing tank (not shown).

[0091] The carbonated cement slurry production system may include a pH measuring unit (not shown) for measuring the pH of the carbonated slurry (including the slurry at least partially carbonated and contained in the slurry tank). Based on the measured pH value of the carbonated slurry, it can be determined whether the carbonated slurry has absorbed and immobilized a target amount of carbon dioxide (whether a sufficient amount of carbon dioxide gas has been absorbed and immobilized in the slurry).

[0092] For example, when the measured pH value of the carbonated slurry in the slurry tank (the slurry at least partially carbonated and contained in the slurry tank) is within a predetermined specified numerical range, it can be determined that a sufficient amount of carbon dioxide gas is absorbed and fixed in the carbonated slurry, and the carbonated slurry in the slurry tank is discharged as a carbonated slurry in which a target amount of carbon dioxide (carbon dioxide gas) is absorbed and fixed.

[0093] In addition, based on the measured pH value of the carbonated slurry, the supply amount of the carbon dioxide-containing gas from the carbon dioxide-containing gas supply device is adjusted (in other words, by increasing or decreasing the supply amount, the pressure of the gas phase composed of the carbon dioxide-containing gas in the first slurry holding unit is adjusted), the circulation of the slurry is adjusted, etc., thereby managing (adjusting) the preparation of the carbonated slurry.

[0094] In addition, regarding the above-mentioned 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 also 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] The pH measuring unit may be provided in a member that stores or transports the carbonated slurry, such as a slurry tank or a slurry circulation path.

[0096] In addition, for the purpose of managing the preparation of carbonated slurry, each component constituting the above-mentioned carbonated slurry manufacturing system can be equipped with various measuring units such as a thermometer for measuring the temperature of the gas phase portion in the slurry tank, a carbonate ion concentration measuring device, an oxygen concentration measuring device, a carbon dioxide concentration measuring device and a pressure gauge.

[0097] Furthermore, these measurement results can be used to perform control using a slurry control device.

[0098] As an example of a method for producing a carbonated slurry using the above-mentioned carbonated slurry production system, which is formed by carbonating a slurry containing calcium powder and water using a gas containing carbon dioxide, the following carbonated slurry production method can be cited, which includes: a slurry preparation step of mixing calcium powder and water to obtain a 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 a manner that a gas phase composed of the gas containing carbon dioxide is located above a first liquid level of the slurry, and in a manner that the 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; a second slurry holding part contained in the slurry tank; a carbonated slurry preparation process, supplying carbon dioxide-containing gas to the gas phase composed of carbon dioxide-containing gas in the first slurry holding part at a pressure greater than atmospheric pressure, so that the first liquid surface contacts the above-mentioned gas phase, thereby carbonated the slurry to obtain carbonated slurry; a carbonated slurry discharge process, continuously discharging the carbonated slurry from the slurry tank; and a liquid level measuring process, measuring the heights of the first liquid level of the first slurry holding part and the second liquid level of the second slurry holding part, and adjusting the supply amount of the slurry per unit time in the slurry supply process and the discharge amount of the carbonated slurry per unit time in the carbonated slurry discharge process based on the measurement results obtained in the liquid level measuring process.

[0099] Explanation of symbols

[0100] 1.21 Carbonation slurry manufacturing system

[0101] 2.22 Slurry tank

[0102] 3.23 Slurry supply device

[0103] 4.24 Carbon dioxide-containing gas supply device

[0104] 5.25 Carbonated slurry discharge device

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

[0106] 7.27 Slurry control device

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

[0108] 9a, 9b, 29a, 29b are gas phases consisting of gases containing carbon dioxide.

[0109] 10a, 10b, 30a, 30b first slurry holding part

[0110] 11a, 11b, 11c, 31 second liquid level

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

[0112] 13, 33 slurry inflow road

[0113] 14.34 Gas containing carbon dioxide flows into the

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

[0115] 16, 36 slurry circulation line

[0116] 18, 38 slurry (including partially carbonated slurry)

[0117] 19, 39 mixing units

[0118] 40a, 40b outflow and inflow ports

Claims

1. A carbonating slurry manufacturing system for manufacturing a carbonating slurry, wherein the carbonating slurry is formed by carbonating a slurry comprising calcium-containing powder and water using a gas containing carbon dioxide, the carbonating 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 second slurry containing portion of the slurry tank; a carbon dioxide-containing gas supply device for supplying the carbon dioxide-containing gas; a carbonated slurry discharge device, configured to continuously discharge the carbonated slurry from the slurry tank; a liquid level measuring unit for measuring the height of the liquid level of the slurry in the slurry tank; and a slurry control device for controlling the average residence time of the slurry, The slurry tank includes: a first slurry containing portion for containing the slurry and the gas containing carbon dioxide 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, so that the slurry and the gas containing carbon dioxide are in contact; and a second slurry holding portion that holds the slurry in a manner such that the gas phase is located above the second liquid level of the slurry and does not have a contact surface between the slurry and the carbon dioxide-containing gas, wherein the first slurry holding portion and the second slurry holding portion are connected via an outflow and inflow port of the first slurry holding portion that enables the slurry to move in and out of the first slurry holding portion. 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 in the first slurry storage part and a second liquid level in the second slurry storage part, 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, the method comprising: carbonating a slurry comprising calcium-containing powder and water by carbonating the slurry with a gas containing carbon dioxide; and comprising: 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 second slurry containing portion of a slurry tank for containing the slurry; a slurry containing step of containing the slurry and the carbon dioxide-containing gas in a first slurry containing portion of the slurry tank such that a gas phase composed of the carbon dioxide-containing gas is located above a first liquid level of the slurry, and containing the slurry in a second slurry containing portion of the slurry tank such that the gas phase is located above a second liquid level of the slurry and there is no contact surface between the slurry and the carbon dioxide-containing gas; a carbonated slurry preparation step of supplying the carbon dioxide-containing gas at a pressure greater than atmospheric pressure to the gas phase composed of the carbon dioxide-containing gas in the first slurry holding portion, so that the first liquid surface contacts the gas phase, thereby carbonated the slurry to obtain 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 heights of the first liquid level in the first slurry containing part and the second liquid level in the second slurry containing part, In the slurry holding step, the first slurry holding portion and the second slurry holding portion are connected via an inlet and outlet of the first slurry holding portion that enables the slurry to move inside and outside the first slurry holding portion. 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.

Images