JP7136577B2 - Carbon dioxide production device, carbon dioxide production method, design method of carbon dioxide production device - Google Patents

Description

The present invention is a carbon dioxide production device, a carbon dioxide production method, and a design of a carbon dioxide production device for producing carbon dioxide by heating cement raw material refined powder, limestone, etc., using heat generated, for example, in a cement production device. It is about the method.

In recent years, attempts to reduce carbon dioxide (CO ₂ ), which is the main cause of global warming, have been promoted worldwide and across all industries. For example, the cement industry is one of the industries that emit a large amount of carbon dioxide, along with electric power, steel, etc., and accounts for about 4% of the total carbon dioxide emissions in Japan. For this reason, it has been considered to recover the exhaust gas containing carbon dioxide generated in the cement manufacturing process without releasing it into the atmosphere.

The recovered carbon dioxide can be reused in a wide range of ways, such as storage in the ground, cultivation of plants and algae, and use as liquefied carbon dioxide for food and industrial raw materials. On the other hand, in order to effectively use the recovered carbon dioxide industrially, it is necessary to raise the concentration of carbon dioxide to a high concentration such as 90 to 100 vol %. In addition, when the recovered carbon dioxide is used for growing plants and algae or as a raw material for food, it is important that it does not contain harmful components.

Exhaust gas obtained by burning thermal energy such as coal, petroleum, and natural gas with pure oxygen in cement kilns and calciners of cement manufacturing equipment contains a large amount of carbon dioxide. volatile organic compounds (VOC), carbon monoxide, nitrogen oxides, sulfur oxides, and other impurities that are harmful to the human body and plants. For this reason, when the obtained exhaust gas containing carbon dioxide is used for growing plants and algae or as a food material, a separate step for removing these impurities is required, and the cost is high as a method for producing carbon dioxide. It has not yet been put to practical use.

On the other hand, Patent Literature 1 describes a method of recovering carbon dioxide by indirectly heating carbon dioxide generated from limestone contained in cement raw material refined powder. This is done by heating cement raw material refinement through a partition wall, or by contacting a heat medium such as overheated calcined cement raw material with the exhaust gas containing carbon dioxide generated during calcining to remove high concentrations of carbon dioxide. It is a method of generating

JP 2009-269785 A

According to the method for recovering carbon dioxide in a cement production facility disclosed in Patent Document 1, it is possible to recover high-concentration carbon dioxide, such as 100 vol %, from exhaust gas generated during cement production. However, the higher the concentration of carbon dioxide to be recovered, the higher the reaction temperature, which increases the cost required for heating. Therefore, there has been a demand for a method for producing carbon dioxide that can produce carbon dioxide at a lower reaction temperature at low cost.

The present invention has been made in view of the above-mentioned circumstances, and is a carbon dioxide production apparatus capable of producing carbon dioxide containing almost no harmful components at low cost, and a carbon dioxide production method using the same. An object of the present invention is to provide a method of designing a carbon dioxide production apparatus.

In order to solve the above problems, the carbon dioxide production apparatus of the present invention includes a gas circulation line for circulating a mixed gas containing carbon dioxide and a diluent medium, a heat exchanger arranged in order in the gas circulation line, a reaction and a separator, a raw material powder supply line, a carbon dioxide recovery line, and a dilution medium supply line connected to the gas circulation line, and a dilution medium separation means formed in the carbon dioxide recovery line. The heat exchanger exchanges heat between the gas circulation line and a high-temperature atmosphere field having a temperature higher than the temperature of the gas circulation line, and the raw material powder supply line exchanges heat with the reactor. or connected to the reactor to supply carbon dioxide production raw material powder to the gas circulation line, and the reactor supplies the production raw material powder to the mixed gas heated by the heat exchanger. Carbon dioxide is generated by a decarboxylation reaction by contacting powder, the separator separates the generated raw material powder and the mixed gas, and the carbon dioxide recovery line transfers the mixed gas to the gas circulation line. system, and the diluent medium supply line supplies the diluent medium to the gas circulation line to reduce the partial pressure of carbon dioxide contained in the mixed gas in the reactor, thereby decarbonating The reaction temperature of the reaction is lowered, and the diluent medium separating means separates the diluent medium from the mixed gas.

According to the carbon dioxide production apparatus of the present invention, a mixed gas containing carbon dioxide and a diluent medium is circulated in the gas circulation line, the diluent medium is supplied from the diluent medium supply line, and the mixed gas is heated in a high-temperature atmosphere. Using this heated mixed gas as a heat source, the raw material powder supplied to the gas circulation line is heated to cause a decarboxylation reaction, whereby carbon dioxide can be continuously and efficiently produced. can.

When carrying out such a decarboxylation reaction, by supplying a diluent medium to the gas circulation line to lower the partial pressure of carbon dioxide contained in the mixed gas, a high temperature such as that of the decarboxylation reaction in an atmospheric pressure environment can be achieved. CO2 can be produced at a lower temperature without the need to

Further, in the present invention, it is preferable that the diluent medium separating means separates carbon dioxide and the diluent medium by utilizing a boiling point difference or a solubility difference between the carbon dioxide and the diluent medium.

Further, in the present invention, the high-temperature atmosphere field is at least one of a cement kiln, a clinker cooler, a preheater, a calciner, and a bleed duct connecting the clinker cooler and the calciner in a cement manufacturing apparatus. It is preferred to include one.

A carbon dioxide production method of the present invention is a carbon dioxide production method using the carbon dioxide production apparatus according to each of the above items, wherein the dilution medium is supplied to the gas circulation line through the dilution medium supply line. a heating step of heating the mixed gas with the heat exchanger; and heating the raw material powder by directly contacting the mixed gas heated in the heating step to cause a decarboxylation reaction to cause a carbon dioxide reaction. A reaction step of producing carbon, a solid-gas separation step of separating the raw material powder and the mixed gas, and the mixed gas containing the carbon dioxide in an amount corresponding to the amount of carbon dioxide produced in the reaction step. and a recovery step of returning the remaining mixed gas to the gas circulation line; and a dilution medium separation step of separating the dilution medium from the mixed gas recovered in the recovery step. do.

According to the carbon dioxide production method of the present invention, a mixed gas containing carbon dioxide and a diluent medium is circulated in the gas circulation line, the diluent medium is supplied to the gas circulation line in the dilution medium supply step, and the mixed gas is supplied in the reaction step. is heated, and using the heated mixed gas as a heat source, the raw material powder supplied to the gas circulation line is heated to cause a decarboxylation reaction, thereby continuously and efficiently producing carbon dioxide can do.

When performing such a decarboxylation reaction, the diluent medium is supplied to the gas circulation line in the diluent medium supply step to reduce the partial pressure of carbon dioxide contained in the mixed gas, so that the decarboxylation reaction can be performed in an atmospheric pressure environment. Carbon dioxide can be produced at a lower temperature without the need for high temperatures such as

Further, in the present invention, in the reaction step, the amount of carbon dioxide produced is the maximum value ± It is preferable to control the supply amount of the raw material powder to the gas circulation line so as to be within the range of 10%.

The carbon dioxide production apparatus design method of the present invention is based on the amount of diluent medium supplied to the gas circulation line and the temperature of the mixed gas after being heated by the heat exchanger, so that the amount of carbon dioxide produced is maximized. The supply amount of the raw material powder to the gas circulation line is determined so as to be within the range of ±10%, and the carbon dioxide production apparatus is designed based on this determination.

According to the present invention, a carbon dioxide production apparatus capable of producing carbon dioxide containing almost no harmful components at low cost, a carbon dioxide production method using the same, and a design method of the carbon dioxide production apparatus are provided. can be done.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the cement production apparatus in which the carbon dioxide production apparatus of this invention and this carbon dioxide production apparatus are installed. It is a schematic diagram which shows an example of a 1st heat exchanger (heat exchanger). It is a schematic diagram which shows an example of a reactor. 2 is the equilibrium vapor pressure curve of carbon dioxide in the decarboxylation reaction of _CaCO3 , the main component of limestone. BRIEF DESCRIPTION OF THE DRAWINGS It is the flowchart which showed the carbon dioxide production method of this invention step by step. It is a graph which shows the relationship between the carbon dioxide production amount and the limestone input amount. It is a graph which shows the relationship between a limestone reaction rate and the amount of carbon dioxide production. It is a graph which shows the relationship between a limestone reaction rate and the amount of limestone input. It is a graph which shows the relationship between post-reaction temperature and a limestone reaction rate. 4 is a graph of a calculation example in which the relationship between C/L and limestone input amount L is plotted for each temperature of a mixed gas containing carbon dioxide. 4 is a graph of a calculation example plotting the relationship between the maximum amount of carbon dioxide produced and the amount of limestone input at that time for each temperature of mixed gas containing carbon dioxide and amount of water vapor supplied. It is a graph of the limestone input amount and the maximum carbon dioxide production amount (recovery amount). 4 is a graph showing the relationship between the amount of steam supplied in the reaction step and the decarboxylation reaction temperature. It is a graph which shows the relationship between the limestone input amount and the production amount of carbon dioxide. It is a graph which shows the relationship between the limestone input amount and the production amount of carbon dioxide.

A carbon dioxide production apparatus and a carbon dioxide production method using the same according to an embodiment of the present invention will be described below with reference to the drawings. It should be noted that each embodiment shown below is specifically described for better understanding of the gist of the invention, and does not limit the invention unless otherwise specified. In addition, in the drawings used in the following description, in order to make it easier to understand the features of the present invention, there are cases where the main parts are enlarged for convenience, and the dimensional ratio of each component is the same as the actual one. not necessarily.

(Carbon dioxide production equipment)
First, the configuration of the cement production apparatus that serves as the supply source of the raw material powder and the high-temperature atmosphere field in the carbon dioxide production apparatus of the present invention will be described.
FIG. 1 is a schematic diagram showing a carbon dioxide production apparatus according to an embodiment of the present invention and a cement production apparatus in which this carbon dioxide production apparatus is installed.
In the following description, the term "mixed gas" refers to a gas in which generated carbon dioxide and a diluent medium are mixed, and may further contain air. In FIG. 1, solid line arrows indicate the flow of gas such as a mixed gas containing carbon dioxide, and dotted line arrows indicate the flow of solids (powder) such as raw material powder.

A cement manufacturing apparatus 30 shown in FIG. The cement manufacturing apparatus 30 shown in FIG. 1 is configured to perform a calcination process, which is an essential part of the cement manufacturing process. (not shown) is provided, and a clinker crusher and a classifier (not shown) are provided in the finishing process, which is a post-sintering process.

The preheater 31 is composed of a plurality of stages of cyclones 31A to 31D arranged in the vertical direction and connected to each other. there is In addition, in this embodiment, the two sets of preheaters 31, 31 are arranged in parallel with each other. Only one set of preheaters 31 may be provided, or three or more sets may be provided.

A cement raw material supply line 42 is connected to the uppermost cyclone 31A, and cement raw material refined powder M is supplied to the uppermost cyclone 31A through this cement raw material supply line 42 from the raw material process, which is the previous process. The refined cement powder M is mainly composed of powdered limestone (CaCO ₃ ), and also contains clay components (SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ ) and the like.

On the other hand, the high-temperature exhaust gas C1 discharged from the calcining furnace 34 is supplied to the lowermost cyclone 31D and flows toward the uppermost cyclone 31A. Then, the exhaust gas C1 that has reached the uppermost cyclone 31A is exhausted through the exhaust line 36 by the exhaust fan 35 .

The refined cement powder M supplied to the uppermost cyclone 31A is preheated by the high-temperature exhaust gas C1 flowing toward the uppermost cyclone 31A as it sequentially falls to the lower cyclones 31B and 31C. The cement raw material refined powder M that has reached the lower cyclone 31C is heated to, for example, about 750° C., and then sent to the calciner 34 via the raw material pipe 37 . The cement raw material refined powder M is further heated to about 850° C. in this calciner 34 by a coal burner 34a.

A raw material powder supply line 21 that is connected to a gas circulation line 11 of a carbon dioxide production apparatus 10, which will be described later, branches off from the middle of the raw material pipe 37 . Part of the raw material refined powder M discharged from the lower cyclone 31C enters the raw material powder supply line 21, and the cement raw material refined powder M after calcination is supplied to the gas circulation line 11 of the carbon dioxide production device 10. supply.

The cement raw material refined powder M heated by the calcining furnace 34 is returned to the preheater 31 again through the calcining furnace exhaust duct 38, and is discharged from the lowermost cyclone 31D through the transfer pipe 39 to the kiln end of the cement kiln 32. It is sent to the section 32a.

The cement kiln 32 includes, for example, a rotatable cylindrical furnace body 32b and a main burner 32c that heats the inside of this furnace body 32b. The preheated refined cement raw powder M supplied from the kiln bottom 32a is heated by the main burner 32c inside the furnace body 32b.

The cement raw material refined powder M heated to, for example, about 1450° C. in the cement kiln 32 undergoes reactions represented by the following formulas (1) to (5).
CaCO ₃ →CaO+CO ₂ (1)
3CaO+SiO ₂ →3CaO·SiO ₂ (2)
2CaO+SiO ₂ →2CaO·SiO ₂ (3)
3CaO+Al ₂ O ₃ →3CaO.Al ₂ O ₃ (4)
_{4CaO + Al2O3 + Fe2O3} → _{4CaO.Al2O3.Fe2O3 ( 5} )
As a result, alite (3CaO.SiO ₂ ) and belite (2CaO.SiO ₂ ), which are calcium silicate compounds finally constituting cement clinker, and an aluminate phase (3CaO.Al ₂ O ₃ ), which is an interstitial phase. and a ferrite phase (4CaO.Al ₂ O ₃ .Fe ₂ O ₃ ) is produced.

The clinker cooler 33 is composed of, for example, a cooling fan, and cools the high-temperature cement clinker produced in the cement kiln 32 . The cement clinker thus cooled is further pulverized and classified into cement in the finishing process.

On the other hand, the high-temperature extraction gas C2 generated when the high-temperature cement clinker is cooled in the clinker cooler 33 is sent to the calcination furnace 34 through the extraction duct 41 connecting the clinker cooler 33 and the calcination furnace 34. . This bleed gas C2 is heated to about 800° C. to 1200° C., for example. In this embodiment, the extraction duct 41 constitutes a high-temperature atmosphere field H in the carbon dioxide production apparatus 10, which will be described later. Further, the extraction duct 41 is provided with a return line for returning quicklime (CaO), which is a solid phase after solid-gas separation in the separator 14 in the carbon dioxide production apparatus 10 described later, and unreacted cement raw material refined powder M. 19 discharge side is connected.

Next, the configuration and action of the carbon dioxide production apparatus of the present invention will be described. The carbon dioxide production apparatus 10 includes a gas circulation line 11 for circulating a mixed gas G containing carbon dioxide, a first heat exchanger (heat exchanger) 12 arranged in this gas circulation line 11 in order, a reactor 13, and It has a separator 14 , a raw material powder supply line 21 connected to the gas circulation line 11 , a carbon dioxide recovery line 22 , and a diluent medium supply line 23 . A second heat exchanger 15 and a circulation pump 16 are further arranged in the gas circulation line 11 .

The gas circulation line 11 is a gas passage through which the mixed gas G containing carbon dioxide flows, is formed in a ring shape, and the mixed gas G is circulated inside. In FIG. 1, the mixed gas G circulates counterclockwise. In addition, through a part of the gas circulation line 11, refined raw cement powder M, which is raw powder to be produced, which will be described later, also flows. Further, the concentration of carbon dioxide contained in the mixed gas G flowing through the gas circulation line 11 is not necessarily uniform throughout the gas circulation line 11, and the concentration of carbon dioxide may differ depending on the section.

The gas circulation line 11 is made of a material that can withstand a high temperature environment, for example, a temperature of 800° C. or higher, such as silicon carbide, alumina, zirconia, or a material containing them. Note that the portion of the gas circulation line 11 where the first heat exchanger 12 and the reactor 13 are formed may be made of a material that can withstand a higher temperature of about 850.degree.

The dilution medium supply line 23 is connected to the gas circulation line 11 between the circulation pump 16 and the first heat exchanger 12, for example. Connected to the dilution medium supply line 23 are a flow control valve 27 for adjusting the supply amount of the dilution medium and a flow meter 26 for detecting the flow rate of the dilution medium. A predetermined flow rate of the diluent medium E is sent into the gas circulation line 11 by the diluent medium supply line 23 . The diluent medium may be supplied by a pump (not shown) or the like. Furthermore, it is also preferable to form a filter or the like in the diluent medium supply line 23 .

The diluent medium E supplied from the diluent medium supply line 23 to the gas circulation line 11 is a substance having a boiling point higher than that of carbon dioxide, particularly a substance that is liquid at room temperature and easily becomes gas by heating to about 100 to 200°C. Furthermore, it is preferable to select a substance that does not dissolve a large amount of carbon dioxide in a liquid state. Such substances include water (water vapor when vaporized), acetone, ethanol, benzene, monoethanolamine, methyldiethanolamine, and the like. In this embodiment, water vapor obtained by vaporizing water is used as the diluent medium E. FIG. In this case, the dilution medium supply line 23 may be connected to a steam supply source such as a boiler.

The first heat exchanger 12 (heat exchanger) exchanges heat between the mixed gas G flowing through the gas circulation line 11 and the high-temperature extraction gas C2 flowing through the extraction duct 41, which is the high-temperature atmosphere field H. The high-temperature atmosphere field H is set to a temperature higher than the temperature of the gas circulation line 11 on the side flowing into the first heat exchanger 12 . For example, the temperature of the gas circulation line 11 at the portion entering the first heat exchanger 12 is about 600.degree. C., and the high-temperature atmosphere field H is about 900.degree. By exchanging heat with the high-temperature atmosphere field H, the mixed gas G flowing through the gas circulation line 11 is heated to, for example, about 850.degree.

FIG. 2 is a schematic diagram showing an example of the first heat exchanger.
The first heat exchanger 12 is formed in the extraction duct 41 of the cement manufacturing apparatus 30, which is an example of the high-temperature atmosphere field H, in this embodiment. Inside the extraction duct 41, a high temperature extraction gas C2 of, for example, about 800.degree. C. to 1000.degree.

The first heat exchanger 12 has a heat exchange tube 17 with a double tube structure having an inner tube 17a and an outer tube 17b. The mixed gas G that has flowed into the first heat exchanger 12 flows inside the inner tube 17a, flows out from the end of the inner tube 17a to the inside of the outer tube 17b, and further flows between the inner tube 17a and the outer tube 17b. flow. In the first heat exchanger 12, the gas circulation line 11 constitutes a channel for the mixed gas G, which is composed of the inner tube 17a and the outer tube 17b.

The inner tube 17a and the outer tube 17b forming the heat exchange tubes 17 of the first heat exchanger 12 are made of silicon carbide (SiC), for example. Silicon carbide is discharged from the mixed gas G, the preheater 31 of the cement production apparatus 30, the cement kiln 32, the clinker cooler 33, the calciner 34, etc. (see FIG. 1) even in a high temperature environment of about 1000°C. It has excellent corrosion resistance against gases containing impurities such as volatile organic compounds (VOC) derived from combustion gases, carbon monoxide, nitrogen oxides, sulfur oxides, etc., and has excellent thermal conductivity. there is According to the first heat exchanger 12 having such a configuration, heat can be efficiently exchanged between the mixed gas G and the extracted gas C2 without deterioration of the constituent materials over a long period of time.

Referring to FIG. 1 again, in the present embodiment, the high-temperature atmospheric field H that exchanges heat with the gas circulation line 11 in the first heat exchanger 12 includes the clinker cooler 33 and the calciner 34 in the cement manufacturing apparatus 30. However, the high-temperature atmosphere field H is not only inside the bleed duct 41, but also in high-temperature parts of the cement manufacturing apparatus 30, such as the cement kiln 32 and the clinker At least one of the cooler 33, the preheater 31, and the calcining furnace 34 may be used.

To the reactor 13 on the downstream side of the first heat exchanger 12 in the gas circulation line 11 is connected a raw material powder supply line 21 for supplying refined cement raw material powder M, which is raw material powder for producing carbon dioxide. This raw material powder supply line 21 supplies the cement raw material refined powder (produced raw material powder) M heated to, for example, about 750° C. by the preheater 31 of the cement manufacturing apparatus 30 to the reactor 13 . The cement raw material refined powder M supplied from the raw material powder supply line 21 directly contacts the mixed gas G heated by the first heat exchanger 12 in the reactor 13 to cause a decarboxylation reaction.

In this embodiment, the raw material powder supply line 21 is connected to the reactor 13, and the cement raw material refined powder M is directly supplied to the reactor 13. 1 A raw material powder supply line 21 is connected between the heat exchanger 12 and the reactor 13 (upstream side of the reactor 13), and the mixed gas G and the cement raw material refined powder M flow into the reactor 13. There may be. Further, the carbon dioxide-generating raw material powder may be high-purity limestone powder or the like in addition to the cement raw material refined powder M. In this embodiment, the refined cement powder M is limestone.

FIG. 3 is a schematic diagram showing an example of a reactor.
The reactor 13 includes, for example, a tubular reaction container 25 . For example, the reaction vessel 25 may be a reaction tube having a diameter larger than that of the piping constituting the gas circulation line 11 in order to increase the residence time of the gas G and promote the reaction. The reaction vessel 25 constitutes a part of the gas circulation line 11, and the mixed gas G heated by the first heat exchanger 12 flows from one end 25a toward the other end 25b. A raw material powder supply line 21 is connected to one end 25a of the reaction vessel 25, and cement raw material refined powder M is supplied into the reaction vessel 25 at a predetermined flow rate.

In the reactor 13, the mixed gas G heated to about 850°C by the first heat exchanger 12 in the reaction vessel 25 is brought into contact with the refined cement powder M heated to about 750°C by the preheater 31. As a result, the cement raw material refined powder M is heated. As a result, limestone (CaCO ₃ ), which is the main component of the refined cement powder M, undergoes a decarboxylation reaction (thermal decomposition reaction: see formula (6) below).
CaCO ₃ →CaO+CO ₂ (6)

It should be noted that the decarboxylation reaction is not necessarily completed in the reactor 13 for the entire amount of the cement raw material refined powder M that is input. The decarboxylation reaction may occur in some cases, and the region where the decarboxylation reaction occurs is not limited.
In addition, not all of the refined raw cement powder M fed from the raw powder supply line 21 undergoes a decarboxylation reaction, and unreacted refined raw cement powder M may remain.

In the reactor 13 (and the entire gas circulation line 11 including this), by supplying the dilution medium E from the dilution medium supply line 23 to the gas circulation line 11, the carbon dioxide contained in the mixed gas G flowing through the gas circulation line 11 is is reduced by the supply of water vapor, which is the diluent medium E.

According to the graph shown in FIG. 4, the reaction temperature of the decarboxylation reaction is lowered by lowering the partial pressure of carbon dioxide below the equilibrium pressure. If steam, which is the dilution medium E, is supplied to the gas circulation line 11 through the dilution medium supply line 23 to reduce the partial pressure of carbon dioxide contained in the mixed gas G, the cement raw material refined powder M is reduced in accordance with the amount of steam supplied. The reaction temperature of the decarboxylation reaction of limestone contained is lowered.
Taking water vapor as the diluent medium of the present embodiment as an example, the amount of supply of the diluent medium is limited to the amount of water vapor that can be used (surplus in a factory or the like) as an upper limit so that the desired amount of carbon dioxide can be produced. preferably determined.

In this embodiment, for example, if water vapor is supplied from the diluent medium supply line 23 to the gas circulation line 11 to set the partial pressure of carbon dioxide in the reactor 13 to 0.33 atm, the reaction temperature of the decarboxylation reaction can be increased to 823°C. can be reduced, and the reaction temperature can be reduced by about 70° C. compared to the decarboxylation reaction in an atmospheric pressure environment.

The flow rate of the mixed gas G flowing into the reactor 13 is preferably adjusted so that the partial pressure of carbon dioxide is 0.1 atm or more and less than 1.0 atm. When the partial pressure of carbon dioxide is lower than 0.1 atm, the reaction temperature can be lowered, but the decarboxylation reaction rate is greatly reduced. Specifically, the reaction temperature is 721° C. when the partial pressure of carbon dioxide is 0.05 atm, and can be lowered to 172° C. compared to the reaction temperature of 893° C. when the partial pressure is 1.0 atm. Since the reaction rate obtained based on (7) is 2/100 of the value at 1.0 atm, it is difficult to efficiently generate carbon dioxide. Moreover, if the partial pressure of carbon dioxide is 1.0 atm or more, the reaction temperature of the decarboxylation reaction cannot be lowered.

The separator 14 separates (solid-gas separates) the mixed gas G flowing through the gas circulation line 11 from the quicklime (CaO) generated in the reactor 13 and unreacted cement raw powder M. The separated quicklime (CaO) and unreacted raw cement powder M are sent to the cement manufacturing apparatus 30 via the return line 19 and used as the raw cement powder M.

Note that the return line 19 may be configured to connect the reactor 13 and the bleed duct 41 as in the present embodiment. and the calcining furnace 34 may be connected to each other.

The second heat exchanger 15 exchanges heat between the mixed gas G flowing through the gas circulation line 11 between the upstream side and the downstream side across the position where the carbon dioxide recovery line 22 is connected in the gas circulation line 11. I do. Specifically, the mixed gas G at about 750° C. that has undergone the decarboxylation reaction in the reactor 13 and the remaining relatively low temperature, such as Heat exchange is performed with mixed gas G of about 300°C. As a result, the temperature of the mixed gas G containing carbon dioxide generated by the decarboxylation reaction in the reactor 13 is lowered to about 300°C, while the temperature of the mixed gas G immediately before entering the first heat exchanger 12 is lowered to about 600°C. temperature is raised.

The circulation pump 16 circulates the mixed gas G through the entire gas circulation line 11 . By arranging this circulation pump 16 downstream of the second heat exchanger 15 described above, the mixed gas G whose temperature has been lowered to about 300° C. by heat exchange by the second heat exchanger 15 flows into the circulation pump 16. Therefore, it is possible to prevent the circulation pump 16 from being damaged or deteriorated due to the inflow of high-temperature gas of 500° C. or higher, for example.

The carbon dioxide recovery line 22 is connected to the downstream side of the circulation pump 16, from which a mixed gas G of carbon dioxide and water vapor as the diluent E is recovered. A flow meter 28 is connected to the carbon dioxide recovery line 22 . The amount of the mixed gas G recovered in the carbon dioxide recovery line 22 (the amount recovered per unit time) is, for example, the amount of carbon dioxide produced by the decarboxylation reaction of the refined cement raw powder M in the reactor 13 ( The amount is adjusted to be the same as the sum of the amount of water vapor supplied from the dilution medium supply line 23 (the amount of water generated per unit time) and the amount of water vapor supplied from the diluent supply line 23 (the amount of water supplied per unit time). As a result, the flow rate and total pressure of the mixed gas G flowing through the gas circulation line 11 are kept constant.

On the downstream side of the flow meter 28 of the carbon dioxide recovery line 22, there is provided a diluent medium separating means that separates the carbon dioxide and the diluent medium E by utilizing the boiling point difference or solubility difference between the carbon dioxide and the diluent medium. ing. In the present embodiment, a condenser (dilution medium separation means) 29 is formed in the carbon dioxide recovery line 22 as a dilution medium separation means for cooling and condensing water vapor, which is the dilution medium E, into water to separate it from carbon dioxide. there is

The mixed gas G containing carbon dioxide and water vapor recovered in the carbon dioxide recovery line 22 is cooled to, for example, less than 100° C. while passing through the condenser 29, and the water vapor is liquefied into water and separated from carbon dioxide. be done. As a result, carbon dioxide obtained by removing water vapor, which is the diluent medium E, from the mixed gas G can be obtained from the carbon dioxide recovery line 22 . The separated water slightly dissolves carbon dioxide, but the water temperature immediately after liquefying the steam is as high as 80° C. to 90° C., and the amount of dissolved carbon dioxide is small.

The carbon dioxide recovered outside the system of the gas circulation line 11 via the condenser 29 provided in the carbon dioxide recovery line 22 is assumed to be used, for example, as a raw material for liquefied carbonic acid, and the concentration range is 90 vol% to 100 vol. %, preferably 95 vol % or more and 100 vol % or less, more preferably 98 vol % or more and 100 vol % or less. For example, the concentration of carbon dioxide is 95vol%.

Note that the diluent medium separating means may be appropriately selected according to the type of diluent medium. For example, in addition to the condenser 29 using the boiling point difference (liquefaction temperature difference), the mixed gas G is passed through (for example, bubbling) the diluent medium absorption liquid in which the diluent medium E is easily soluble and does not dissolve carbon dioxide. , a dissolver for separating the carbon dioxide and the diluent medium E, or the like.

(Carbon dioxide production method)
The carbon dioxide production method of the present invention using the carbon dioxide production apparatus 10 configured as above will be described.
FIG. 5 is a flow chart showing step by step the carbon dioxide production method of the present invention.
When producing carbon dioxide having a predetermined concentration using the carbon dioxide producing apparatus 10 , first, the mixed gas G containing carbon dioxide and water vapor is circulated through the gas circulation line 11 by the circulation pump 16 .

Further, from the preheater 31 of the cement manufacturing apparatus 30, for example, cement raw material refined powder (produced raw material powder) M heated to about 750° C. is supplied to the gas circulation line 11 through the raw material powder supply line 21. . Further, water vapor, which is the dilution medium of the present embodiment, is supplied from the dilution medium supply line 23 toward the gas circulation line 11 (dilution medium supply step S1). By supplying steam, the partial pressure of carbon dioxide in the reactor 13 is set to, for example, about 0.33 atm through the gas circulation line 11 .

Then, in the first heat exchanger (heat exchanger) 12 formed in the bleed duct 41, which is the high temperature atmosphere field H provided in the cement manufacturing apparatus 30, the high temperature bleed gas C2 flowing through the bleed duct 41 and the gas circulation Heat is exchanged with the mixed gas G flowing through the line 11, and the temperature of the mixed gas G entering the reactor 13 is heated to, for example, about 850° C. (heating step S2).

In addition to the extraction duct 41 connecting the clinker cooler 33 and the calciner 34, the high-temperature atmosphere field H in which the first heat exchanger 12 is provided includes high-temperature parts in the cement manufacturing apparatus 30, such as the cement kiln 32 and the clinker cooler. At least one of 33, preheater 31, and calcining furnace 34 may be used.

Next, in the reactor 13, the cement raw material refined powder M is heated using the mixed gas G containing carbon dioxide heated in the heating step S2 as a heat source. Cement raw material refined powder M is heated to about 850° C. to 900° C. by high-temperature mixed gas G, for example. As a result, limestone (CaO ₃ ), which is the main component of the cement raw material refined powder M, produces carbon dioxide through a decarboxylation reaction (reaction step S3).

The partial pressure of carbon dioxide contained in the mixed gas G in the reactor 13 is set to, for example, about 0.33 atm by supplying water vapor to the gas circulation line 11 . As a result, the reaction temperature at which limestone decarboxylation occurs is lowered to about 823° C. (see FIG. 4). Due to the reduction in the partial pressure of carbon dioxide due to the supply of water vapor, the refined cement raw powder M undergoes a decarboxylation reaction even at about 850° C., which is lower than the reaction temperature of 893° C. at atmospheric pressure, and carbon dioxide and Decomposes into quicklime (CaO).

The partial pressure of carbon dioxide contained in the mixed gas G is preferably 0.1 atm or more. If the partial pressure of carbon dioxide is 0.1 atm or less, the reaction rate is greatly reduced, and the amount of carbon dioxide produced per unit time is too small to be practical.

In the reactor 13, limestone (CaCO ₃ ), which is the main component of the refined cement powder M, undergoes a decarboxylation reaction from the outside to the inside of each particle. For this reason, with each particle of limestone (CaCO ₃ ), as the reaction time elapses, the reacted substance (CaO) accumulates on the outside of the particle, and the carbon dioxide generated from the unreacted CaCO ₃ on the center side , passes through this reacted substance (CaO) and is released to the outside of the particles. Thus, each particle of CaCO ₃ slows down as the reaction time elapses.

The reaction rate of such decarboxylation reaction of CaCO ₃ particles is shown by the following equation (7).
K=(1−X) ^2/3 ×A・exp(−E/ _RGT )×{1−(P _All・P _CO2 )/P _{CO2_eq} }…(7)
K: reaction rate [1/s]
A: 2.2×10 ⁸ [1/s]
E: 2.0×10 ⁵ [J/mol]
R _G : gas constant 8.314
T: Temperature [K]
P _All : Total pressure [atm]
P _CO2 : CO ₂ partial pressure [atm]
P _{CO2_eq} : Equilibrium _CO2 partial pressure [atm]
X: reaction rate

This equation (7) shows the reaction rate when the CaCO ₃ particles are spherical, and considering the effect of carbon dioxide gas boundary film diffusion, the equilibrium partial pressure of carbon dioxide at a predetermined temperature is obtained, and the reactor It is corrected by the ratio of the carbon dioxide partial pressure in 13 and the product of the mixed gas total pressure. The amount of reaction was calculated from the product of the reaction rate coefficient and the residence time in the reactor. The temperature dependence of the equilibrium partial pressure can be measured using a thermobalance or the like.

It was supplied per unit time by supplying so that the molar weight velocity of limestone (CaCO ₃ ), which is the main component of the refined cement raw powder M, is higher than the molar weight velocity of carbon dioxide generated in the reactor 13. A set amount of carbon dioxide can be produced in a shorter period of time than when the entire amount of limestone in the refined cement powder M is reacted.

In such a reaction step S3, the amount of carbon dioxide produced is within a calculated maximum value ±10% based on the amount of water vapor supplied in the diluent medium supply step S1 and the temperature of the mixed gas G after being heated in the heating step S2. The amount of cement raw material refined powder (produced raw material powder) M supplied to the gas circulation line 11 is controlled so that

The control of the decarboxylation reaction in the reaction step S3 will be described below.
For example, when a portion of limestone powder such as cement raw material refined powder M is taken from a cement manufacturing process such as the cement manufacturing apparatus 30 shown in FIG. , it can be assumed that the temperature of limestone does not fluctuate greatly. Therefore, since the reaction time in the reactor 13 can also be considered constant in a fluidized bed or the like, the items to be considered are the amount of limestone input, the partial pressure of carbon dioxide, and the mixed gas G containing carbon dioxide flowing through the reactor 13. is the gas temperature.

The inventors of the present invention found that the partial pressure of carbon dioxide controlled by the amount of diluent supply in the diluent supply line 23 and the temperature of the mixed gas G after being heated in the first heat exchanger (heat exchanger) 12 is measured, and depending on the temperature, the reaction pressure or carbon dioxide partial pressure of the decarboxylation reaction, which is the manufacturing condition for maximizing the amount of carbon dioxide produced (or carbon dioxide concentration) at that time, and the limestone powder The inventors have found a method of controlling the decarboxylation reaction in the reactor 13 based on the results of obtaining the input amount in advance by chemical engineering calculations.

First, by actual measurement or calculation in advance, an approximate curve is created using the method of least squares from the relationship between the amount of limestone input and the amount of carbon dioxide produced for each supply amount of the diluent medium. Then, the maximum amount of carbon dioxide produced under each condition and the amount of limestone input at that time are obtained. In addition, it may be determined from the relationship between the reaction rate of limestone and the amount of carbon dioxide produced, the relationship between the reaction rate of limestone and the amount of limestone input, the temperature after the decarboxylation reaction, and the reaction rate of limestone.

As a calculation example showing such a relationship, FIG. 6 shows a graph of the relationship between the amount of carbon dioxide produced and the amount of limestone input. Also, FIG. 7 shows a graph of the relationship between the limestone reaction rate and the amount of carbon dioxide produced. Further, FIG. 8 shows a graph of the relationship between the limestone reaction rate and the amount of limestone input. Further, FIG. 9 shows a graph of the relationship between post-reaction temperature and limestone reaction rate.

In these calculation examples, the diluent medium supply rate is set to 75 L/min, 100 L/min, 125 L/min, and 150 L/min (each converted to 0° C.), and the mixed gas of carbon dioxide and the diluent medium is gas circulated. It is set as a condition for circulating in the line.

Also, the CO ₂ recovery amount can be calculated from the difference between the value of the flow meter 26 that detects the flow rate of the dilution medium and the value of the flow meter 28 that detects the recovery flow rate of the mixed gas. That is, this CO ₂ recovery amount is the amount of carbon dioxide produced by the decarboxylation reaction in the reactor 13 . From the graphs shown in FIGS. 6 to 9, it can be seen that the amount of carbon dioxide recovered takes a maximum value at a specific reaction rate or limestone input amount for each diluent medium supply amount.

Next, for each temperature of the mixed gas G after being heated in the first heat exchanger (heat exchanger) 12, the maximum amount of carbon dioxide produced and the amount of limestone input at that time are obtained. The resulting values are plotted on a graph of limestone input versus maximum carbon dioxide production. At that time, the horizontal axis is dimensionless with the limestone input amount (L) as the reference, and the vertical axis is the value obtained by dividing the maximum carbon dioxide generation amount C by L on a molar basis per unit time (C / L), the dilution medium supply The amount (M) and the circulation amount (R) of the mixed gas are similarly expressed as (M/L) and (R/L).

FIG. 10 shows a graph of a calculation example in which the relationship between C/L and the amount of limestone input L is plotted for each temperature of the mixed gas containing carbon dioxide. Further, FIG. 11 shows a graph of a calculation example in which the relationship between the maximum amount of carbon dioxide produced and the amount of limestone input at that time is plotted for each temperature of the mixed gas containing carbon dioxide and the amount of water vapor supplied. In the graphs of FIGS. 10 and 11, an approximation curve (hereinafter referred to as an "equal supply amount line") connecting conditions with the same steam supply amount (or mixed gas circulation amount) is created. Also, an approximation curve (hereinafter referred to as an isothermal line) connecting conditions with the same mixed gas temperature is created.

Also, in creating the graphs shown in FIGS. 10 and 11, limestone at 750° C. was mixed so that the mixed gas after heat exchange flowing in the gas circulation line was 900° C. and 1200 L/min (converted to 0° C.). Assuming that the reaction time in the reactor 13 where the decarboxylation reaction occurs is 10 seconds, the amount of carbon dioxide produced is adjusted, and the water vapor supply rates are 75 L/min, 100 L/min, 125 L/min, and 150 L/min (each of which is 0 ℃ conversion), and calculated the amount of carbon dioxide produced (recovered amount) when changing the amount of limestone input, the reaction rate of the decarboxylation reaction, and the temperature after the reaction.

Then, as shown in FIG. 12, the desired amount of carbon dioxide produced and the value of the assumed amount of limestone input are drawn in the graph of the amount of limestone input and the maximum amount of carbon dioxide produced (recovery amount) and designated as point X. Let points A, B, C, and D be points of intersection of the two iso-supply lines and the two isothermal lines surrounding this point X, respectively.

Rectangular areas partitioned by line segments AB, BC, CD, and AD connecting the intersections A, B, C, and D thus created, respectively, are shown in FIG. Divide into minutes. The finer the number of divisions, the higher the calculation accuracy. Then, grid-like auxiliary lines (broken lines in FIG. 13) connecting the division points are created.

Then, by examining the distance between the point X indicating the assumed amount of limestone input and the iso-supply line and isothermal line surrounding this point X, and proportionally dividing according to the distance, the decarboxylation reaction that satisfies the point X The reaction pressure and the temperature of the mixed gas can be determined.
In addition, if the line segments AB, BC, CD, and AD deviate significantly from the iso-supply lines and isotherms, narrow the interval between the iso-supply lines or isotherms to improve the calculation accuracy. be able to.

The calculation examples shown in FIGS. 12 and 13 are for a decarboxylation reaction that satisfies a mixed gas circulation rate of 1200 L/min, a carbon dioxide production rate of 30.1 L/min, and a limestone input rate of 37.9 kg/h. The pressure and the temperature of the mixed gas are calculated.
From the plot shown in FIG. 13, it is read that the temperature of the mixed gas: (925×3+900×7)/10=907.5° C. and the steam supply rate: (125×3+150×7)/10=142.5 L/min. When the maximum carbon dioxide production amount and the limestone input amount at that time are obtained under these conditions, the carbon dioxide production amount: 30.1 L / min, the limestone input amount: 37.9 kg / hour, and the desired carbon dioxide production amount is 30 L. /min, and when the assumed limestone input amount is set to 38 kg/h, calculations can be made with errors of 0.3% and -0.3%, respectively.

The prediction accuracy can be further improved by increasing the number of divisions until the point X is passed. The figure created in such an embodiment is dimensionless with the limestone input amount (L) as a reference of 24.46 kg / hour (244.5 mol / hour), so that the same one as in FIG. 11 can be obtained. can be done.

In the gas circulation line 11 on the downstream side of the reactor 13, the mixed gas G, the quicklime produced by the decarboxylation reaction, the unreacted cement raw powder M remaining without reacting in the reactor 13, etc. flowing towards

In addition, in such control, fluctuations in the amount of carbon dioxide produced due to fluctuations in the temperature of the high temperature field and the amount of dilution medium supplied in actual operation, Considering the amount of production and cost performance, if the amount of limestone input is controlled to be within ± 10% of the maximum amount of carbon dioxide produced in the calculation, the same effect can be obtained. is preferably controlled so that the amount of generated is within the calculated maximum value ±10% (see FIGS. 14 and 15).

In the separator 14, a mixed gas (gas) G containing carbon dioxide is separated from powders (solids) such as quicklime produced by the decarboxylation reaction and unreacted cement raw material refined powder M (solid-gas separation step S4). The quicklime (CaO) separated by the separator 14 and the unreacted cement raw material refined powder M are discharged to the extraction duct 41, sent to the calciner 34 of the cement manufacturing apparatus 30, and effective as the cement raw material refined powder M. used.

The temperature of the mixed gas G separated from solid and gas through the separator 14 is about 750° C., and if it enters the circulation pump 16 on the downstream side of the gas circulation line 11 as it is, there is a concern that the circulation pump 16 will be damaged by heat. In this embodiment, the second heat exchanger 15 is arranged between the circulation pump 16 and the separator 14 . The mixed gas G at about 750° C. flowing into the second heat exchanger 15 has a temperature lowered to about 300° C. on the downstream side of the connection position of the carbon dioxide recovery line 22, and the mixture flowing through the gas circulation line 11 Heat is exchanged with gas G.

As a result, the temperature of the mixed gas G flowing into the circulation pump 16 is lowered to, for example, about 300.degree. On the other hand, the mixed gas G flowing into the first heat exchanger 12 by circulation is heated to, for example, about 600° C. by the second heat exchanger 15, and the mixed gas G is heated to about 850° C. in the first heat exchanger 12. Helps keep the temperature warm.
The second heat exchanger 15 does not always have to be provided, and can be omitted depending on the characteristics of the circulation pump 16 and the temperature of the mixed gas G flowing into the first heat exchanger 12 .

Part of the mixed gas G containing carbon dioxide and water vapor that has passed through the circulation pump 16 is recovered outside the system of the gas circulation line 11 from the carbon dioxide recovery line 22 connected to the gas circulation line 11 (recovery step S5 ).

In the recovery step S5, the amount of the mixed gas G containing carbon dioxide and water vapor recovered through the carbon dioxide recovery line 22 (amount recovered per unit time) is, for example, the cement raw material refined powder M is adjusted to be the same as the total amount of the amount of carbon dioxide produced by the decarboxylation reaction (the amount of production per unit time) and the amount of diluent medium supplied through the diluent medium supply line 23 . Thereby, the flow rate and pressure of the mixed gas G circulating in the gas circulation line 11 can be kept constant.

The mixed gas G containing carbon dioxide and water vapor recovered in the carbon dioxide recovery line 22 passes through a condenser (dilution medium separating means) 29 . At this time, the mixed gas G is cooled to, for example, less than 100° C., and water vapor is liquefied and condensed into water, which is separated from carbon dioxide (dilution medium separation step S6). As a result, carbon dioxide obtained by removing water vapor, which is the dilution medium E, from the mixed gas G is obtained from the carbon dioxide recovery line 22 . The concentration of the obtained carbon dioxide is 90 vol% or more and 100 vol% or less, for example, the concentration is 95 vol%.

On the other hand, the water separated by the condenser (dilution medium separating means) 29 can be used as a supply material for steam supplied from the dilution medium supply line 23 or can be reused for cooling the condenser 29 or the like.

The diluent medium separation means can be appropriately selected according to the type of diluent medium. may be dissolved in a solvent and separated from carbon dioxide.

By introducing water vapor from the dilution medium supply line 23 to the gas circulation line 11, impurities such as chlorine and water-soluble organic matter derived from the cement raw material refined powder M are removed when the cement raw material refined powder M is used as the raw material powder to be produced. is adsorbed by water vapor. When water vapor is condensed into water by the condenser 29, these chlorine and water-soluble organic matter can be dissolved in water and removed. As a result, the concentration of impurities in carbon dioxide after recovery can be further reduced.

After that, the mixed gas G that has not been recovered in the carbon dioxide recovery line 22 is heated to, for example, about 600° C. by the second heat exchanger 15, and then the above-described steps are repeated from the dilution medium supply step S1.

As described above, according to the carbon dioxide production apparatus 10 of the present invention and the carbon dioxide production method using the same, the mixed gas G containing carbon dioxide and water vapor (dilution medium) is circulated in the gas circulation line 11 and , water vapor (dilution medium) is supplied from the dilution medium supply line 23, the mixed gas G is heated in the high-temperature atmosphere field H, and the heated gas is used as a heat source to purify the cement raw material supplied to the gas circulation line 11. Carbon dioxide (mixed gas G) can be continuously and efficiently produced by heating the powder (produced raw material powder) M to cause a decarboxylation reaction.

When performing such a decarboxylation reaction, by supplying water vapor (dilution medium) to the gas circulation line 11 to reduce the partial pressure of carbon dioxide contained in the mixed gas, the decarboxylation reaction can be performed in an atmospheric pressure environment. Since there is no need to raise the temperature to a high temperature close to 900° C., the mixed gas G is heated using the high temperature atmosphere field H of the cement manufacturing apparatus whose maximum temperature is about 800 to 850° C., and this mixed gas is used as a heat source for cement raw materials. Carbon dioxide can be produced from refined powder M at low cost.

In addition, according to the present invention, since it does not contain carbon dioxide generated by burning fossil fuels such as coal, petroleum, and natural gas, volatile organic compounds (VOC), carbon monoxide, and nitrogen oxidation contained in these combustion exhaust gases There is no concern about containing impurities harmful to the human body and plants such as sulfur oxides, and since the concentration of carbon dioxide after separation from the diluent medium is high, it can be effectively used industrially as, for example, liquefied carbonic acid.

Furthermore, the first heat exchanger (heat exchanger) for heating the mixed gas G serving as a heat source for causing a decarboxylation reaction in the limestone contained in the cement raw material refined powder M includes, for example, cement raw material refined powder containing limestone. Since the solid (powder) does not flow into the first heat exchanger, the solid (powder) does not adhere to the first heat exchanger and clog the flow path, and carbon dioxide can be stably produced at low maintenance cost. can.

According to the carbon dioxide production method of the present invention, in the reaction step, the amount of carbon dioxide produced is the maximum value ± Carbon dioxide can be produced with maximum efficiency by controlling the amount of raw material powder supplied to the gas circulation line so that it falls within the range of 10%. Thereby, carbon dioxide can be produced in large quantities at low cost.

(Method for designing carbon dioxide production equipment)
The carbon dioxide production apparatus design method of the present invention is based on the amount of diluent medium supplied to the gas circulation line and the temperature of the mixed gas after being heated by the heat exchanger. The supply amount of raw material powder to the gas circulation line is determined so as to be within the range of 10%, and the carbon dioxide production apparatus is designed based on this determination.

Specifically, in designing the carbon dioxide production apparatus, the amount of diluent medium supplied to the gas circulation line described above, the temperature of the mixed gas after being heated by the heat exchanger, and the raw material powder to the gas circulation line Based on the relationship between the supply amount of and the amount of carbon dioxide produced, the dilution medium supply amount of the dilution medium supply line and the heating temperature by heat exchange of the mixed gas in the first heat exchanger (heat exchanger) are set. Therefore, it is possible to design a carbon dioxide production apparatus that maximizes the production efficiency of carbon dioxide, such as by selecting the high-temperature atmosphere field H for installing the first heat exchanger.

Although several embodiments of the invention have been described above, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 10... Carbon dioxide production apparatus 11... Gas circulation line 12... 1st heat exchanger (heat exchanger)
13... Reactor 14... Separator 15... Second heat exchanger 16... Circulation pump 21... Raw material powder supply line 22... Carbon dioxide recovery line 23... Dilution medium supply line 25... Reaction vessel 29... Aggregator (dilution medium separation means)
DESCRIPTION OF SYMBOLS 31... Preheater 32... Cement kiln 33... Clinker cooler 34... Calcination furnace E... Dilution medium G... Mixed gas H... High temperature atmosphere field M... Cement raw material refined powder

Claims (6)

A gas circulation line for circulating a mixed gas containing carbon dioxide and a diluent medium, a heat exchanger, a reactor, and a separator sequentially arranged in the gas circulation line, and raw material powder connected to the gas circulation line. a supply line, a carbon dioxide recovery line, a dilution medium supply line, and a dilution medium separation means formed in the carbon dioxide recovery line;
The heat exchanger exchanges heat between the gas circulation line and a high-temperature atmosphere field having a temperature higher than the temperature of the gas circulation line,
The raw material powder supply line is connected between the reactor and the heat exchanger or connected to the reactor to supply raw material powder for generating carbon dioxide to the gas circulation line,
The reactor brings the raw material powder into contact with the mixed gas heated by the heat exchanger to produce carbon dioxide through a decarboxylation reaction,
The separator separates the raw material powder and the mixed gas,
The carbon dioxide recovery line recovers the mixed gas outside the system of the gas circulation line,
The diluent medium supply line supplies the diluent medium to the gas circulation line to lower the partial pressure of carbon dioxide contained in the mixed gas in the reactor, thereby lowering the reaction temperature of the decarboxylation reaction. ,
The carbon dioxide production apparatus, wherein the diluent medium separating means separates the diluent medium from the mixed gas. 2. The carbon dioxide production apparatus according to claim 1, wherein said diluent medium separating means separates carbon dioxide and said diluent medium by utilizing a boiling point difference or a solubility difference between carbon dioxide and said diluent medium. The high-temperature atmospheric field includes at least one of a cement kiln, a clinker cooler, a preheater, a calciner, and a bleed duct connecting the clinker cooler and the calciner in the cement manufacturing apparatus. 3. The carbon dioxide production apparatus according to claim 1 or 2. A carbon dioxide production method using the carbon dioxide production apparatus according to any one of claims 1 to 3,
a dilution medium supply step of supplying a dilution medium to the gas circulation line through the dilution medium supply line;
a heating step of heating the mixed gas with the heat exchanger;
a reaction step in which the raw material powder is brought into direct contact with the mixed gas heated in the heating step and heated to cause a decarboxylation reaction to produce carbon dioxide;
a solid-gas separation step of separating the raw material powder and the mixed gas;
a recovery step of recovering the mixed gas containing the carbon dioxide in an amount corresponding to the amount of carbon dioxide generated in the reaction step, and refluxing the remaining mixed gas to the gas circulation line;
and a dilution medium separation step of separating the dilution medium from the mixed gas recovered in the recovery step. In the reaction step, the production amount of carbon dioxide is within a maximum value of ±10% based on the amount of the diluent medium supplied in the diluent medium supply step and the temperature of the mixed gas after being heated in the heating step. 5. The method for producing carbon dioxide according to claim 4, wherein the supply amount of the raw material powder to the gas circulation line is controlled so that The method for designing a carbon dioxide production apparatus according to any one of claims 1 to 3,
Based on the amount of diluent medium supplied to the gas circulation line and the temperature of the mixed gas after being heated by the heat exchanger, the amount of carbon dioxide produced is within the maximum value ± 10%. 2. A method of designing a carbon dioxide production apparatus, comprising: determining a supply amount of the raw material powder to be supplied to the gas circulation line; and designing the carbon dioxide production apparatus based on this determination.

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