JP7257582B1 - Carbon dioxide fixation device and carbon dioxide fixation method - Google Patents

Abstract

A carbon dioxide fixation device and a carbon dioxide fixation method capable of efficiently fixing carbon dioxide are provided. A carbon dioxide fixation device (1) stirs a first intermediate (6) added with water while stirring a concrete sludge (2) from which coarse aggregate and fine aggregate have been removed, to a solid content (14) obtained by solid-liquid separation. Hydrating and stirring means 15 for obtaining the second intermediate 17 with water while adding water, reaction means 22 for obtaining the third intermediate 25 by reacting the second intermediate 17 with carbon dioxide, and dehydrating the third intermediate 25 and dewatering means 35 for producing the powder 3 . [Selection drawing] Fig. 1

Description

TECHNICAL FIELD The present invention relates to a carbon dioxide fixation apparatus and a carbon dioxide fixation method for producing powder from concrete sludge.

Conventionally, there is known a carbon dioxide fixation apparatus for obtaining calcium carbonate by reacting carbon dioxide with the calcium component of concrete sludge generated in the concrete manufacturing process. In this carbon dioxide fixation device, solid-liquid separation is performed on the first intermediate added with water while the concrete sludge is stirred, and silicon dioxide is separated from the liquid and reacted with carbon dioxide to produce calcium carbonate ( For example, see Patent Document 1).

Japanese Patent Application Laid-Open No. 2009-136770

Since the water-soluble calcium component is determined by the saturation concentration, a large amount of calcium component remains in the solid content obtained by solid-liquid separation of the first intermediate. Therefore, it is desired to effectively utilize the calcium component remaining in this solid content to fix more carbon dioxide.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a carbon dioxide fixing device and a carbon dioxide fixing method capable of efficiently fixing carbon dioxide.

In the carbon dioxide fixation device according to claim 1, concrete sludge from which coarse aggregates and fine aggregates have been removed is stirred while adding water to the first intermediate , which is a sludge cake obtained by solid-liquid separation. a means for obtaining a third intermediate by reacting carbon dioxide with the second intermediate; a means for obtaining a third intermediate by dehydrating the third intermediate; and dewatering means for manufacturing.

The carbon dioxide fixation device according to claim 2 is the carbon dioxide fixation device according to claim 1 , wherein the adding and stirring means adds water in an amount of 4 times or more and 10 times or less with respect to the weight of the solid content. .

The carbon dioxide fixation device according to claim 3 is the carbon dioxide fixation device according to claim 1 or 2, wherein the water content of the solid content is 40% or more and 60% or less.

In the carbon dioxide fixation method according to claim 4, the concrete sludge from which coarse aggregate and fine aggregate have been removed is stirred while water is added, and the solid content is a sludge cake obtained by solid-liquid separation. A water stirring step of obtaining a second intermediate with water while adding water, a reaction step of reacting carbon dioxide with the second intermediate to obtain a third intermediate, and a powder by dehydrating the third intermediate and a dehydration step for producing the

The method for fixing carbon dioxide according to claim 5 is the method for fixing carbon dioxide according to claim 4, wherein in the adding and stirring step, water is added in an amount of 4 to 10 times the weight of the solid content. .

The method for fixing carbon dioxide according to claim 6 is the method for fixing carbon dioxide according to claim 4 or 5, wherein the water content of the solid content is 40% or more and 60% or less.

According to the present invention, carbon dioxide can be efficiently immobilized.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing which shows the carbon dioxide fixation apparatus of one embodiment of this invention.

An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, 1 is a carbon dioxide fixation device. The carbon dioxide fixation device 1 is a powder production device that uses concrete sludge 2 as a raw material to produce dry powder 3 in which carbon dioxide is fixed.

Concrete sludge 2 is concrete sludge generated during the production of secondary concrete products. Secondary concrete products refer to products such as concrete columns and concrete piles, which are obtained by solidifying concrete materials composed of cement, water, fine aggregates, coarse aggregates, and admixtures. In particular, the concrete sludge 2 is generated in the centrifugal molding process during the manufacture of secondary concrete products. Concrete sludge generated in the centrifugal molding process is qualitatively equivalent to mortar sludge and cement paste sludge. Therefore, coarse aggregate and fine aggregate are removed from the concrete sludge 2 and the powder 3 . The powder 3 produced by the carbon dioxide fixation device 1 of the present embodiment does not contain aggregate (such as stone powder) having a particle diameter of 0.5 mm or more. The powder 3 is a carbon dioxide immobilized powder in which carbon dioxide is immobilized, and is a carbon dioxide adsorbent having a carbon dioxide adsorption function.

The concrete sludge 2 is a highly alkaline material rich in cement-derived calcium (Ca) components. The calcium component is an effective component for carbon dioxide adsorption.

Further, the concrete sludge 2 used in this embodiment has a water-cement ratio (W/C) of approximately 1. For example, the concrete sludge 2 has a component ratio of 49.9% cement, 49.9% water, and 0.2% fine sand. The cement content contains about 30% calcium component.

Concrete sludge 2 is concrete sludge generated in secondary concrete product factories, residual concrete (residual concrete) in ready-mixed concrete plants, or returned concrete (returned concrete) separated into coarse aggregate and fine aggregate. may be used. That is, the concrete sludge 2 is all surplus fresh concrete.

The carbon dioxide fixation device 1 includes water adding means 5 . The hydrating means 5 is for obtaining the first intermediate 6 by adding water WI1 to the concrete sludge 2 while stirring. As an example, the adding means 5 has an elution tank 8 and a stirring means 9 installed in the elution tank 8 . As the stirring means 9, for example, a rotating blade is used. With respect to the weight of the concrete sludge 2, the smaller the amount of water added, the higher the efficiency of carbon dioxide adsorption, and the larger the amount of water added, the more suppressed the development of strength due to the hydration reaction. In the present embodiment, the adding means 5 adds water WI1 in an amount of 4 to 10 times the weight of the concrete sludge 2 . If the amount of water added is less than 4 times the weight of the concrete sludge 2, the stickiness of the concrete sludge 2 will be high, and if it is more than 10 times, the concentration of calcium ions will decrease, respectively, and the carbon dioxide adsorption efficiency will decrease. Therefore, for example, when the amount of water added is 10 times the weight of the concrete sludge 2, the component ratio of the first intermediate 6 is 5% cement, 95% water, and 0% fine sand.

The carbon dioxide fixation device 1 also includes separation means 11 for solid-liquid separation of the first intermediate 6 . Separating means 11 is means such as a filter press. The first intermediate 6 discharged from the elution tank 8 of the hydration means 5 through the discharge part 12 by the separation means 11 is separated into a liquid content 13 and a solid content 14 .

The liquid portion 13 is a highly alkaline liquid in which a part of the calcium component contained in the concrete sludge 2 is eluted. By adding water and stirring the concrete sludge 2 by the water adding means 5, the calcium component contained in the cement in the concrete sludge 2 is eluted into the water, and the water in which the calcium component is eluted is separated by the separating means 11 into a liquid. 13 minutes. The calcium component eluted in the liquid portion 13 is determined by the saturation concentration. For example, in the case of calcium hydroxide, the calcium saturation concentration is about 0.1%. Among the calcium components contained in, a predetermined amount of calcium components is eluted depending on the saturation concentration. In this liquid portion 13, although not shown, a gas containing carbon dioxide, for example, an exhaust gas from a gas supply source such as a boiler or a power plant, is reacted with the calcium component to generate light calcium carbonate and fix carbon dioxide. It is possible to

The solid content 14 is also called sludge cake or the like, and is highly alkaline and mainly composed of calcium hydroxide. The solid content 14 separated by the separating means 11 has a moisture content of 40% or more and 60% or less, preferably 50%. For example, when the water content of the solid content 14 is less than 40%, the rate of calcium elution from the solid content 14 in the adding stirring means 15 is low. Moreover, when the water content of the solid content 14 is more than 60%, the solid content 14 is in the form of a slurry, which is difficult to handle industrially. This solid content 14 contains a large amount of calcium components that could not be eluted into the water by the adding and stirring treatment in the adding means 5 .

In addition, the carbon dioxide fixation device 1 is provided with water adding and stirring means 15 . The adding and agitating means 15 may be connected to the separating means 11, and the solid content 14 transported by a transporting means such as a vehicle from facilities such as a factory having the adding means 5 and the separating means 11 is introduced. may be configured.

The adding and stirring means 15 is for obtaining the second intermediate 17 by adding water WI2 to the solid content 14 while stirring. As an example, the adding and stirring means 15 has an elution tank 20 and a stirring means 21 installed in the elution tank 20 . As the stirring means 21, for example, a rotating blade is used. With respect to the weight of the solid content 14, the smaller the amount of water added, the higher the efficiency of the amount of carbon dioxide adsorbed, and the larger the amount of water added, the more suppressed the development of strength due to the hydration reaction. In the present embodiment, water WI<b>2 is added in an amount of 4 times or more and 10 times or less of the weight of the solid content 14 in the adding/stirring means 15 . If the amount of water added is less than 4 times the weight of the solid content 14, the stickiness of the solid content 14 will increase, and if it is more than 10 times, the calcium ion concentration will decrease, and the adsorption efficiency of carbon dioxide will decrease respectively.

Furthermore, the carbon dioxide fixation device 1 comprises reaction means 22 . The reaction means 22 is directly connected to the adding and stirring means 15, and supplies the gas G containing carbon dioxide to the second intermediate 17 directly obtained from the adding and stirring means 15, thereby obtaining the third intermediate 25. be. As an example, the reaction means 22 has a reaction vessel 27 and a gas supply means 28 installed in the reaction vessel 27 .

The reaction tank 27 is formed in a longitudinal shape in the vertical direction. The second intermediate 17 is introduced into the reaction tank 27 from above through the discharge part 30 from the elution tank 20 of the water stirring means 15 . In the present embodiment, the reaction tank 27 has a reaction tank main body 32 having a cylindrical outer surface and a reduced part 33 having a conical outer surface integrally in the vertical direction, and the axial direction thereof extends along the vertical direction. are placed. The reaction vessel main body 32 is cylindrical with a constant or substantially constant diameter. The reduced portion 33 is coaxially connected to the lower portion of the reaction vessel body portion 32 and has a downwardly reduced diameter.

The gas supply means 28 reacts carbon dioxide in the gas G with the calcium component of the solid content 14 contained in the second intermediate 17 to generate calcium carbonate and fix carbon dioxide. The gas supply means 28 has pipes, valves, nozzles, etc. connected to a gas supply source. The gas supply means 28 is connected to the lower part of the reaction tank 27 and causes the gas G to be ejected from the lower part of the reaction tank 27 for a predetermined period of time. The ejection of the gas G by the gas supply means 28 may be continuous or intermittent.

Exhaust gas from a gas supply source such as a boiler or a power plant is preferably used as the gas G supplied by the gas supply means 28 . This gas G contains 5% or more and 25% or less of carbon dioxide, for example.

Furthermore, the carbon dioxide fixation device 1 includes dehydration means 35 . The dehydration means 35 directly obtains the third intermediate 25 from the reaction means 22 and dehydrates the third intermediate 25 to produce the powder 3 . In the present embodiment, the dewatering means 35 drains the third intermediate 25 by its own weight (natural dehydration). That is, the dewatering means 35 of the present embodiment is a non-driving device that does not include a power source or a heat source. As the dewatering means 35, for example, a flexible container bag or the like is preferably used. That is, the dehydrating means 35 is formed in a bag-like shape by a nonwoven fabric made of chemical fibers or the like, and holds the powder 3 inside while discharging water WO or the like having particles smaller than the powder 3 from the bottom or the periphery. is. The dehydration means 35 is supplied with the third intermediate 25 led out of the reaction tank 27 from the lead-out part 38 at the bottom of the reaction tank 27 of the reaction means 22 . The dehydrating means 35 may be forcibly dried depending on the application of the powder 3 to be produced.

Next, a method for fixing carbon dioxide (a method for producing the powder 3) by the apparatus for fixing carbon dioxide 1 of the present embodiment will be described.

First, the concrete sludge 2 is introduced into the elution tank 8 of the hydrating means 5 . When a predetermined amount of concrete sludge 2 is introduced into the elution tank 8, the adding means 5 adds a predetermined amount of water WI1 to the concrete sludge 2 in the elution tank 8 and agitates the concrete sludge 2 in the agitation means 9 to obtain a first intermediate. Get body 6.

Subsequently, the first intermediate 6 is solid-liquid separated into a liquid portion 13 and a solid portion 14 by the separation means 11 . In this embodiment, the solid content 14 is conveyed to the adding and stirring means 15 and introduced into the elution tank 20 . Regarding the liquid portion 13, it is possible to separately react a gas containing carbon dioxide with the calcium component to fix the carbon dioxide and generate light calcium carbonate.

When a predetermined amount of the solid content 14 is introduced into the elution tank 20, the addition stirring means 15 adds a predetermined amount of water WI2 to the solid content 14 in the elution tank 20 and stirs the solid content 14 by the stirring means 21 to produce a second Intermediate 17 is obtained.

Furthermore, this second intermediate 17 is introduced from above into the reaction vessel 27 of the reaction means 22 via the discharge section 30 . In the reaction means 22, the carbon dioxide adsorption function (DAC Direct Air Capture) function) reacts the calcium component contained in the second intermediate 17 with carbon dioxide to produce calcium carbonate, and the third intermediate 25 in which carbon dioxide is immobilized on the second intermediate 17 is generated.

By operating the carbon dioxide fixing device 1 for a predetermined time, a third intermediate 25 in which carbon dioxide is adsorbed on the concrete sludge 2 is produced in the reaction tank 27 . After that, the third intermediate 25 is introduced into the dehydrating means 35 through the outlet 38 of the reaction tank 27 of the reaction means 22 , and the water WO is dehydrated by the dehydrating means 35 to produce the powder 3 . The powder 3 produced through the dehydration means 35 has a carbon dioxide adsorption rate of about 25% and a water content ranging from 4% to 40%, which can be set according to the application of the powder 3.

The manufactured powder 3 consists of light calcium carbonate produced by reaction of a saturated calcium solution with carbon dioxide, cement carbonated powder which is a cement component whose surface is coated with calcium carbonate, and non-carbonated powder. It is a complex carbon dioxide-fixing powder containing three types of cement content, which is a solid content of cement, and carbonation unreacted powder of cement content. Although the powder 3 contains a very small amount of fine sand, the component ratio can be substantially ignored.

In addition, the manufactured powder 3 not only has carbon dioxide fixed in the manufacturing process, but also has a further carbon dioxide adsorption function inside it, and has a function of adsorbing carbon dioxide over time, that is, a slow rate It exhibits a strong carbon dioxide adsorption function.

For example, the powder 3 produced according to the present embodiment is applied as an admixture for concrete kneading, an asphalt pavement filler material, an auxiliary material for soil improvement materials, and an auxiliary material for backfill injection materials such as tunnels. In addition to being easy to use, it is possible to utilize carbon dioxide-fixed substances by applying them.

Therefore, it is possible not only to effectively use the concrete sludge 2, which has been discarded as industrial waste in the past and discharges more than 3 million tons per year, to produce powder, but also to counter global warming caused by carbon dioxide. In addition, it can be suitably used for CCU (Carbon dioxide Capture and Utilization) that captures and effectively utilizes carbon dioxide.

Thus, according to one embodiment, the first intermediate 6 added with water while stirring the concrete sludge 2 from which coarse aggregate and fine aggregate have been removed is stirred with respect to the solid content 14 obtained by solid-liquid separation. After obtaining the second intermediate 17 with water while adding water, reacting the second intermediate 17 with carbon dioxide to obtain the third intermediate 25, the third intermediate 25 is dehydrated to produce the powder 3 By doing so, a large amount of the calcium component remaining in the solid content 14 obtained by solid-liquid separation of the first intermediate 6 can be further utilized to efficiently immobilize carbon dioxide. Therefore, compared to the case where the solid content 14 is dried as it is and used as a dephosphorization material or a cement admixture, it is possible to greatly increase the amount of carbon dioxide that can be immobilized, and the carbon dioxide is immobilized. The fine powder 3 can be produced, resulting in a more efficient flow.

By adding water in an amount of 4 to 10 times the weight of the solid content 14 during stirring with water, the solid content 14 can be stirred with an appropriate amount of water to produce the second intermediate 17 sent to the reaction means 22 .

In addition, the dehydration means 35 drains the third intermediate 25 by its own weight, so that it is not necessary to use power or the like, and it is possible to suppress an increase in carbon dioxide emissions due to power consumption when fixing carbon dioxide.

Since the water content of the solid content 14 is 40% or more, the elution rate of the calcium component can be ensured during the water stirring by the water stirring means 15, and since the water content of the solid content 14 is 60% or less, water stirring can be performed. The solid content 14 is easy to handle during transportation to the means 15 or the like.

In the above embodiment, the second intermediate 17 is further subjected to solid-liquid separation, the liquid content is reacted with a gas containing carbon dioxide to produce light calcium carbonate, and the solid content is added again. A second intermediate 17 may be produced by stirring. In other words, since the amount of calcium soluble in water has an upper limit, if the calcium component remains in the solid content, the formation of the second intermediate 17, its solid-liquid separation, and the reaction of carbon dioxide to the liquid content , and the formation of the second intermediate 17 by adding water to the solid content and stirring it, are repeated any number of times, so that the calcium component contained in the concrete sludge 2 can be effectively used and the amount of fixed carbon dioxide can be further increased. .

1 Carbon Dioxide Fixation Device 2 Concrete Sludge 3 Powder 6 First Intermediate 14 Solid Content 15 Water Agitation Means 17 Second Intermediate 22 Reaction Means 25 Third Intermediate 35 Dehydration Means

Claims (6)

Water stirring to obtain a second intermediate to which water is added while stirring the solid content , which is a sludge cake, by solid-liquid separation of the first intermediate to which water is added while stirring concrete sludge from which coarse aggregate and fine aggregate have been removed. means and
a reaction means for obtaining a third intermediate by reacting the second intermediate with carbon dioxide;
dehydration means for dehydrating the third intermediate to produce powder;
A carbon dioxide fixation device comprising: 2. The carbon dioxide fixation device according to claim 1, wherein the adding and stirring means adds water in an amount of 4 to 10 times the weight of the solid content. The carbon dioxide fixation device according to claim 1 or 2, wherein the moisture content of the solid content is 40% or more and 60% or less. Water stirring to obtain a second intermediate to which water is added while stirring the solid content , which is a sludge cake, by solid-liquid separation of the first intermediate to which water is added while stirring concrete sludge from which coarse aggregate and fine aggregate have been removed. process and
a reaction step of obtaining a third intermediate by reacting carbon dioxide with the second intermediate;
A dehydration step of dehydrating the third intermediate to produce powder;
A carbon dioxide fixation method comprising: 5. The carbon dioxide fixation method according to claim 4, wherein in the adding and stirring step, water is added in an amount of 4 to 10 times the weight of the solid content. The carbon dioxide fixation method according to claim 4 or 5, wherein the water content of the solid content is 40% or more and 60% or less.

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