JP7020253B2 - Carbon dioxide production equipment, carbon dioxide production method, design method of carbon dioxide production equipment - Google Patents

Description

The present invention uses, for example, a carbon dioxide production apparatus for producing low-concentration carbon dioxide by heating cement raw material refined powder, limestone, etc. using heat generated in a cement production apparatus, a carbon dioxide production method, and carbon dioxide. It relates to a method of designing a manufacturing device.

In recent years, attempts to reduce carbon dioxide (CO ₂ ), which is a major cause of global warming, have been promoted worldwide and throughout all industries. For example, the cement industry is one of the industries that emit a large amount of carbon dioxide along with electric power and steel, and accounts for about 4% of the total carbon dioxide emissions in Japan. Therefore, it is 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 widely reused, such as by storing it in the ground, growing plants and algae, and using it as liquefied carbonic acid for food raw materials and industrial raw materials. When the recovered carbon dioxide is used for growing plants and algae and as a raw material for food, it is important that it does not contain harmful components.

The exhaust gas obtained by burning thermal energy such as coal, oil, and natural gas with pure oxygen in the cement kiln and calcination furnace of cement manufacturing equipment contains a large amount of carbon dioxide, but this exhaust gas is derived from combustion gas. It contains impurities harmful to humans and plants such as volatile organic compounds (VOC), carbon monoxide, nitrogen oxides, and sulfur oxides. Therefore, when the obtained exhaust gas containing carbon dioxide is used for growing plants and algae or as a raw material for food, a separate step for removing these impurities is required, which is expensive as a method for producing carbon dioxide. It has not yet been put into practical use.

On the other hand, Patent Document 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 to heat the cement raw material fine powder through the partition wall, or to bring a heat medium such as a preheated cement raw material that has been overheated into contact with the exhaust gas containing carbon dioxide generated during the calcination to generate a high concentration of carbon dioxide. It is a method to generate.

Japanese Unexamined Patent Publication No. 2009-269785

However, the method for recovering carbon dioxide in the cement manufacturing apparatus shown in Patent Document 1 cannot be used as it is for growing plants and algae because it produces carbon dioxide having a high concentration of about 100 vol%. A new process such as reducing the concentration of the generated high-concentration carbon dioxide by using a diluting gas is required. Therefore, there has been a demand for a carbon dioxide production device and a carbon dioxide production method capable of producing carbon dioxide having a low concentration and containing no harmful components at a low cost, which is suitable for growing plants and algae.

The present invention has been made in view of the above-mentioned circumstances, and is a carbon dioxide production apparatus capable of efficiently producing low-concentration carbon dioxide containing almost no harmful components, and carbon dioxide using the same. It is an object of the present invention to provide a manufacturing method and a design method of a carbon dioxide producing device.

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 air, and heat exchangers and reactors sequentially arranged in the gas circulation line. The heat exchanger comprises a raw material powder supply line, a carbon dioxide recovery line, and an air supply line connected to the gas circulation line, and the heat exchanger includes the gas circulation line and the gas circulation line. The gas circulation is performed by exchanging heat with a high temperature atmosphere field having a temperature higher than the temperature of the above, and the raw material powder supply line is connected between the reactor and the heat exchanger or connected to the reactor. The raw material powder for producing carbon dioxide is supplied to the line, and the reactor is brought into contact with the mixed gas heated by the heat exchanger to generate carbon dioxide by a decarbonization reaction, and the above-mentioned The separator separates the produced raw material powder and the mixed gas, the carbon dioxide recovery line recovers the mixed gas out of the system of the gas circulation line, and the air supply line circulates the air to the gas circulation. It is characterized by supplying to the line.

According to the carbon dioxide production apparatus of the present invention, air is supplied from an air supply line to circulate a mixed gas containing carbon dioxide in a gas circulation line, and the mixed gas heated in a high temperature atmosphere field is used as a heat source. By heating the produced raw material powder supplied to the gas circulation line to cause a decarbonization reaction, low-concentration carbon dioxide diluted with air can be continuously and efficiently produced. The obtained low-concentration carbon dioxide can be used as it is for growing plants in a plant factory or growing algae in a green oil manufacturing plant without diluting it.

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 an air extraction duct connecting the clinker cooler and the calciner in a cement manufacturing apparatus. It is preferable to include one.

Further, in the present invention, the produced raw material powder separated by the separator is returned to at least one of the cement kiln, the preheater, the calcination furnace, and the bleeding duct. It is preferable to further provide a return line.

The 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, and includes an air supply step of supplying air to the gas circulation line via the air supply line. The heating step of heating the mixed gas with the heat exchanger and the generated raw material powder in direct contact with the mixed gas heated in the heating step are heated to cause a decarbonization reaction to generate carbon dioxide. A solid air separation step for separating the produced 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 are recovered. It is characterized by comprising a recovery step of returning the remaining mixed gas to the gas circulation line.

According to the carbon dioxide production method of the present invention, air is supplied from the air supply line in the air supply process to circulate the mixed gas containing carbon dioxide in the gas circulation line, and the mixture is heated in a high temperature atmosphere field in the heating process. Using gas as a heat source, the raw material powder supplied to the gas circulation line is heated to cause a decarbonization reaction, thereby continuously and efficiently producing low-concentration carbon dioxide diluted with air. be able to. The obtained low-concentration carbon dioxide can be used as it is for growing plants in a plant factory or growing algae in a green oil manufacturing plant without diluting it.

Then, when the decarbonation reaction is performed, air is supplied to the gas circulation line to reduce the partial pressure of carbon dioxide contained in the mixed gas, thereby creating a high temperature environment such as the decarbonation reaction in an atmospheric pressure environment. Since it is not necessary, a lower temperature heat source, for example, a high temperature atmosphere field of a cement manufacturing apparatus, is used to heat the mixed gas, and this mixed gas is used as a heat source to efficiently remove low-concentration carbon dioxide from the cement raw material refined powder. Moreover, it can be produced at low cost.

Further, in the present invention, in the reaction step, the maximum amount of carbon dioxide produced is ± 10% based on the amount of air supplied in the air supply step and the temperature of the mixed gas after being heated in the heating step. It is preferable to control the supply amount of the produced raw material powder to the gas circulation line so as to be within the range of.

The method for designing the carbon dioxide producing apparatus of the present invention is the method for designing the carbon dioxide producing apparatus according to each of the above items, wherein the amount of air supplied to the gas circulation line and the amount of air supplied after being heated by the heat exchanger are used. Based on the temperature of the mixed gas, the supply amount of the produced raw material powder to the gas circulation line is determined so that the amount of carbon dioxide produced is within the range of the maximum value ± 10%, and based on this determination. The carbon dioxide production apparatus is designed.

According to the present invention, a carbon dioxide production apparatus capable of efficiently producing low-concentration carbon dioxide containing almost no harmful components, a carbon dioxide production method using the carbon dioxide production apparatus, and a carbon dioxide production apparatus design method. Can be provided.

It is a schematic diagram which shows the carbon dioxide production apparatus of this invention, and the cement production apparatus in which this carbon dioxide production apparatus is installed. It is a schematic diagram which shows an example of the 1st heat exchanger (heat exchanger). It is a schematic diagram which shows an example of a reactor. It is a graph which showed the equilibrium vapor pressure curve of carbon dioxide in the decarboxylation reaction of CaCO ₃ which is a main component of limestone. It is a flowchart which showed the carbon dioxide production method of this invention step by step. It is a graph which shows the relationship between the amount of carbon dioxide production and the amount of limestone input. It is a graph which shows the relationship between the limestone reaction rate and the amount of carbon dioxide production. It is a graph which shows the relationship between the limestone reaction rate and the limestone input amount. It is a graph which shows the relationship between the temperature after a reaction and the limestone reaction rate. It is a graph of the calculation example which plotted the relationship between C / L and the amount of limestone input for each temperature of a mixed gas containing carbon dioxide and (A / L). It is a graph of the calculation example which plotted the relationship between the maximum carbon dioxide production amount and the limestone input amount at that time for each temperature of a mixed gas containing carbon dioxide and (A / L). It is a graph of the amount of limestone input and the maximum amount of carbon dioxide produced (recovered amount). It is a graph which shows the calculation example in a reaction process. It is a graph which shows the calculation example in a reaction process. It is a graph which shows the relationship between the amount of limestone input and the amount of carbon dioxide produced. It is a graph which shows the relationship between the amount of limestone input and the amount of carbon dioxide produced.

Hereinafter, the carbon dioxide production apparatus according to the embodiment of the present invention and the carbon dioxide production method using the carbon dioxide production apparatus will be described with reference to the drawings. It should be noted that each of the embodiments shown below is specifically described in order to better understand the gist of the invention, and is not limited to the present invention unless otherwise specified. In addition, the drawings used in the following description may be shown by enlarging the main parts for convenience in order to make the features of the present invention easy to understand, and the dimensional ratios of each component are the same as the actual ones. It is not always the case.

(Carbon dioxide production equipment)
First, the configuration of the cement manufacturing apparatus that serves as the source of the produced raw material powder and the high temperature atmosphere field in the carbon dioxide producing apparatus of the present invention will be described.
FIG. 1 is a schematic view showing a carbon dioxide producing apparatus according to an embodiment of the present invention and a cement manufacturing apparatus in which the carbon dioxide producing apparatus is installed.
In the following description, low-concentration carbon dioxide is carbon dioxide having a concentration of 1 vol% or more and 50 vol% or less. Further, in the following description, when referring to a mixed gas, a gas in which air (nitrogen, oxygen, argon, carbon dioxide in the air (concentration: about 0.03%), etc.) is mixed with the generated carbon dioxide (that is, low-concentration carbon dioxide). Carbon). Further, in FIG. 1, the solid arrow indicates the flow of a gas such as a mixed gas containing carbon dioxide, and the dotted arrow indicates the flow of a solid (powder) such as a raw material powder.

The cement manufacturing apparatus 30 shown in FIG. 1 includes a preheater 31, a cement kiln 32, a clinker cooler 33, and a calciner 34. The cement manufacturing apparatus 30 shown in FIG. 1 has a configuration for performing a firing step, which is a main part of the cement manufacturing process. In the raw material process, which is a pre-process of the firing step, a raw material crusher and a raw material mixer are used. (Not shown) is provided, and a clinker crusher and a classifier (not shown) are provided in the finishing step, which is a subsequent step of the firing step.

The preheater 31 is composed of a plurality of stages of cyclones 31A to 31D arranged in the vertical direction connected to each other, and the cyclones 31A to 31D of the stages adjacent to each other in the vertical direction are arranged so as to be horizontally offset from each other. There is. In this embodiment, two sets of preheaters 31 and 31 are arranged in parallel with each other. The preheater 31 may be provided in only one set or in three or more sets.

A cement raw material supply line 42 is connected to the uppermost cyclone 31A, and the cement raw material refined powder M is supplied from the raw material process, which is a previous step, to the uppermost cyclone 31A via the cement raw material supply line 42. The main component of the cement raw material refined powder M is 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. The exhaust gas C1 that has reached the uppermost cyclone 31A is exhausted by the exhaust fan 35 via the exhaust line 36.

The cement raw material refined 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 on 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 calcination furnace 34 via the raw material pipe 37. The cement raw material refined powder M is further heated to about 850 ° C. by a coal burner 34a in this calcining furnace 34.

From the middle of the raw material pipe 37, the raw material powder supply line 21 connected to the gas circulation line 11 of the carbon dioxide production apparatus 10 described later branches. A part of the cement 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 calcining is put into the gas circulation line 11 of the carbon dioxide production apparatus 10. Supply.

The cement raw material refined powder M heated by the calcination furnace 34 is returned to the preheater 31 again via the calcination furnace exhaust duct 38, and is returned to the preheater 31 from the bottom cyclone 31D via the transfer pipe 39 to the kiln tail of the cement kiln 32. It is sent to the unit 32a.

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

The cement raw material fine powder M heated to, for example, about 800 to 900 ° C. in the cement kiln 32 causes the 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 _{2O 3} → 3CaO ・ Al _{2O 3} ... (4)
4CaO + Al ₂ O ₃ + Fe ₂ O ₃ → 4CaO ・ Al ₂ O ₃・ Fe ₂ O ₃ ... (5)
As a result, alite (3CaO · SiO ₂ ) and belite (2CaO · SiO ₂ ), which are calcium silicate compounds finally constituting the cement clinker, and an aluminate phase (3CaO · Al _{2O 3} ) which is a pore phase. And a ferrite phase (4CaO, Al ₂ O ₃ , Fe ₂ O ₃ ) is generated.

The clinker cooler 33 is composed of, for example, a cooling fan, and cools the high-temperature cement clinker produced by the cement kiln 32. The cement clinker cooled in this way is further crushed and classified in the finishing process to become cement.

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

Next, the configuration and operation 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 that circulates a mixed gas G containing carbon dioxide, a first heat exchanger (heat exchanger) 12, a reactor 13, and a reactor 13 that are sequentially arranged in the gas circulation line 11. It includes a separator 14, a raw material powder supply line 21 connected to a gas circulation line 11, a carbon dioxide recovery line 22, and an air supply line 23. Further, 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 flow path through which the mixed gas G containing carbon dioxide flows, is formed in a ring shape, and the mixed gas G circulates inside. In FIG. 1, the mixed gas G circulates in the counterclockwise direction. A cement raw material refined powder M, which is a raw material powder described later, also flows in a part of the gas circulation line 11. Further, the concentration of carbon dioxide contained in the mixed gas G flowing through the gas circulation line 11 is not always uniform in the entire gas circulation line 11, and the concentration of carbon dioxide may differ depending on the section. In the present embodiment, the mixed gas G flowing through the gas circulation line 11 is low-concentration carbon dioxide diluted with air, and the concentration of carbon dioxide is in the range of 1 vol% or more and 50 vol% or less.

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

The air supply line 23 is connected to the gas circulation line 11 between, for example, the circulation pump 16 and the first heat exchanger 12. A flow rate adjusting valve 27 for adjusting the amount of air supplied and a flow meter 26 for detecting the flow rate of air are connected to the air supply line 23. By such an air supply line 23, a preset flow rate of air E is sent into the gas circulation line 11. The air may be supplied by a pump (not shown) or the like. Further, it is also preferable to form a filter or the like on the air supply line 23.

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 bleed air gas C2 flowing through the bleed air duct 41 which is a 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 in the portion entering the first heat exchanger 12 is about 600 ° C., and the high temperature atmosphere field H is about 900 ° C. 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 ° C.

FIG. 2 is a schematic diagram showing an example of the first heat exchanger.
In the present embodiment, the first heat exchanger 12 is formed in the bleed air duct 41 of the cement manufacturing apparatus 30 which is an example of the high temperature atmosphere field H. Inside the bleed air duct 41, a bleed air gas C2 having a high temperature of, for example, about 800 ° C. flows from the clinker cooler 33 toward the calcining furnace 34.

The first heat exchanger 12 has a double pipe structure including an inner pipe 12a and an outer pipe 12b, and the mixed gas G flowing into the first heat exchanger 12 flows inside the inner pipe 12a and is an inner pipe. It flows out from the end of 12a to the inside of the outer pipe 12b, and further flows between the inner pipe 12a and the outer pipe 12b. In the first heat exchanger 12, the gas circulation line 11 is composed of a flow path of a mixed gas G composed of an inner pipe 12a and an outer pipe 12b.

The inner pipe 12a and the outer pipe 12b constituting the first heat exchanger 12 are formed of, for example, silicon carbide (SiC). Silicon carbide is discharged from the mixed gas G, the preheater 31 of the cement manufacturing apparatus 30, the cement kiln 32, the cleaner cooler 33, the calcination furnace 34, and the like (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 gas, carbon monoxide, nitrogen oxides, and sulfur oxides, and also has excellent thermal conductivity. There is. According to the first heat exchanger 12 having such a configuration, the constituent materials do not deteriorate for a long period of time, and heat can be efficiently exchanged between the mixed gas G and the bleed air gas C2.

With reference to FIG. 1 again, in the present embodiment, in the first heat exchanger 12, the high temperature atmosphere field H that exchanges heat with the gas circulation line 11 includes the cleed air cooler 33 and the calciner 34 in the cement manufacturing apparatus 30. In addition to the inside of the bleed air duct 41, the high temperature atmosphere field H is a high temperature portion of the cement manufacturing apparatus 30, for example, a cement kiln 32 and a clinker having a temperature of about 800 to 850 ° C. At least one of the cooler 33, the preheater 31, and the calciner 34 may be used.

A raw material powder supply line 21 for supplying cement raw material refined powder M, which is a raw material powder for producing carbon dioxide, is connected to the reactor 13 on the downstream side of the first heat exchanger 12 in the gas circulation line 11. The 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 decarbonization reaction.

In the present 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, but in addition to this, for example, the first. 1 The 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 raw material powder for producing carbon dioxide may be a high-purity limestone powder or the like, in addition to the cement raw material fine powder M. In this embodiment, the case where the cement raw material fine powder M is limestone is exemplified.

FIG. 3 is a schematic diagram showing an example of a reactor.
The reactor 13 includes, for example, a tubular reaction vessel 25. The reaction vessel 25 may be, for example, a reaction vessel having a diameter equal to or larger than that of the pipe constituting the gas circulation line 11 in order to prolong the residence time of the gas G and promote the reaction. The reaction vessel 25 forms 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 to the other end 25b. Further, a raw material powder supply line 21 is connected to one end 25a of the reaction vessel 25, and the cement raw material refined powder M is supplied into the reaction vessel 25 at a predetermined flow rate.

In the reactor 13, the cement raw material fine powder M heated to about 750 ° C. by the preheater 31 is brought into contact with the mixed gas G heated to about 850 ° C. by the first heat exchanger 12 in the reaction vessel 25. By allowing the cement raw material fine powder M to be heated. This causes a decarboxylation reaction (pyrolysis reaction: see the following formula (6)) of limestone (CaCO ₃ ), which is the main component of the cement raw material fine powder M.
CaCO ₃ → CaO + CO ₂ ... (6)

The decarboxylation reaction is not always completed in the reactor 13 with the total amount of the cement raw material refined powder M input from the raw material powder supply line 21, for example, from the reactor 13 to the separator 14 on the downstream side. A decarboxylation reaction may occur in the pipe of the gas circulation line 11, and the region where the decarboxylation reaction occurs is not limited.
Further, the cement raw material refined powder M input from the raw material powder supply line 21 does not necessarily cause a decarboxylation reaction in the entire amount of the cement raw material refined powder M, and unreacted cement raw material refined powder M may remain.

In the reactor 13 (and the entire gas circulation line 11 including the reactor 13), by supplying air E from the air supply line 23 to the gas circulation line 11, the amount of carbon dioxide contained in the mixed gas G flowing through the gas circulation line 11 is contained. The pressure drops by the amount of air supplied.

Here, for example, at atmospheric pressure (1 atm), the decarboxylation reaction proceeds until the carbon dioxide in the system of the gas circulation line 11 reaches a concentration (partial pressure) of 1 vol% or more and 50 vol% or less by heating the limestone. The temperature required for decarboxylation is defined as the reaction temperature. In the following description, the reaction temperature means the above-mentioned temperature.
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 the air E is supplied to the gas circulation line 11 by the air supply line 23 and the partial pressure of carbon dioxide contained in the mixed gas G is lowered, the limestone contained in the cement raw material fine powder M is charged according to the supply amount of the air E. The reaction temperature of the decarboxylation reaction decreases.

For example, if the partial pressure of carbon dioxide is set to 0.33 atm by adding air E, the reaction temperature of the decarboxylation reaction can be lowered to 823 ° C. In the present embodiment, the partial pressure of carbon dioxide in the reactor 13 is set to 0.33 atm by supplying air E from the air supply line 23 to the gas circulation line 11. As a result, the reaction temperature can be lowered by about 70 ° C. as compared with the decarboxylation reaction in the atmospheric pressure environment.

By decarboxylating limestone, which is the main component of the cement raw material refined powder M, in the reactor 13, carbon dioxide in the same amount as the amount of carbon dioxide contained in the mixed gas G recovered in the carbon dioxide recovery line 22 is generated. Will be done.

In the mixed gas G flowing into the reactor 13, the partial pressure of carbon dioxide is preferably 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 reaction rate of the decarboxylation reaction is greatly reduced. Specifically, the reaction temperature when the partial pressure of carbon dioxide is 0.05 atm is 721 ° C, which can be lowered to 172 ° C with respect to the reaction temperature of 893 ° C when the partial pressure of carbon dioxide is 1.0 atm. Since the reaction rate obtained based on (7) is two-hundredths of the value at 1.0 atm, it is difficult to efficiently generate carbon dioxide. Further, 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 separation) the mixed gas G flowing through the gas circulation line 11 from the quicklime (CaO) generated in the reactor 13 and the unreacted cement raw material fine powder M. The quicklime (CaO) separated here and the unreacted cement raw material fine powder M are sent to the cement manufacturing apparatus 30 and used as the cement raw material fine powder M.

In addition to the configuration in which the reactor 13 and the bleeding duct 41 are connected as in the present embodiment, the return line 19 is, for example, the reactor 13 and the cement kiln 32, the reactor 13 and the preheater 31, and the reactor 13. And the calciner 34 may be connected to each other.

The second heat exchanger 15 exchanges heat between the mixed gases G flowing through the gas circulation line 11 between the upstream side and the downstream side sandwiching 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., which was decarboxylated by the reactor 13, and the remaining relatively low temperature, for example, a part of the mixed gas G recovered on the carbon dioxide recovery line 22 on the downstream side, for example. Heat exchange is performed with the mixed gas G at 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 drops to about 300 ° C., while the temperature of the mixed gas G immediately before entering the first heat exchanger 12 reaches about 600 ° C. The temperature is raised.

The circulation pump 16 circulates the mixed gas G in the entire gas circulation line 11. By arranging the circulation pump 16 on the downstream side 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 having a temperature 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 the mixed gas G, which is a low concentration carbon dioxide, is recovered. A flow meter 28 is connected to the carbon dioxide capture line 22. The amount of the mixed gas G recovered by the carbon dioxide recovery line 22 (recovery amount per unit time) is, for example, the amount of carbon dioxide produced by the decarbonation reaction of the cement raw material refined powder M in the reactor 13. The amount produced per unit time) and the amount of air E supplied from the air supply line 23 (supply amount per unit time) are adjusted to be the same as the summed amount. As a result, the flow rate and the total pressure of the mixed gas G flowing through the gas circulation line 11 are kept constant.

The mixed gas G, which is a low-concentration carbon dioxide recovered to the outside of the gas circulation line 11 via the carbon dioxide recovery line 22, has a carbon dioxide concentration in the range of 1 vol% or more and 50 vol% or less. By diluting the high-concentration carbon dioxide generated by decarboxylation of the limestone contained in the cement raw material refined powder M with the reactor 13 with air, the mixed gas G which is the low-concentration carbon dioxide as described above Can be obtained.

The carbon dioxide capture line 22 may be further formed with a decompression pump (not shown) capable of depressurizing the reactor 13 via the gas circulation line 11. By depressurizing the reactor 13 below the atmospheric pressure by such a decompression pump, the reaction temperature of the decarboxylation reaction of the limestone contained in the cement raw material refined powder M is further increased by the partial pressure reduction of carbon dioxide due to the supply of air E and the decompression. It can be further reduced. In addition to being connected to the carbon dioxide capture line 22, such a decompression pump can be connected to any location on the gas circulation line 11 if the reactor 13 can be depressurized.

(Carbon dioxide production method)
The carbon dioxide production method of the present invention using the carbon dioxide production apparatus 10 having the above configuration will be described.
FIG. 5 is a flowchart showing the carbon dioxide production method of the present invention step by step.
When producing a mixed gas having a low concentration of carbon dioxide of, for example, about 33 vol% (partial pressure 0.33 atm) using the carbon dioxide production apparatus 10, first, the circulation pump 16 is used to lower the gas circulation line 11. A mixed gas G containing carbon dioxide having a concentration of, for example, 33 vol% (partial pressure 0.33 atm) is circulated.

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

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

The high temperature atmosphere field H provided with the first heat exchanger 12 has a high temperature portion in the cement manufacturing apparatus 30, such as a cement kiln 32 and a clinker cooler, in addition to the bleed air duct 41 connecting the clinker cooler 33 and the calciner 34. At least one of 33, the preheater 31, and the calciner 34 may be used.

Next, in the reactor 13, the cement raw material fine powder M is heated using the mixed gas G containing carbon dioxide heated in the heating step S2 as a heat source. The cement raw material refined powder M is heated to, for example, about 850 ° C. to 900 ° C. by a high-temperature mixed gas G. As a result, limestone (CaO ₃ ), which is the main component of the cement raw material refined powder M, produces carbon dioxide by 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 air to the gas circulation line 11. As a result, the reaction temperature at which the decarboxylation reaction of limestone occurs is lowered to about 823 ° C. (see FIG. 4). The cement raw material refined powder M undergoes a decarboxylation reaction even at about 850 ° C, which is lower than the reaction temperature at atmospheric pressure of 893 ° C, due to the decrease in the partial pressure of carbon dioxide due to the supply of air, and is the main component. Some limestone decomposes into carbon dioxide and quicklime (CaO).

In the reactor 13, the decarboxylation reaction of limestone (CaCO ₃ ), which is the main component of the cement raw material refined powder M, proceeds from the outside to the inside of each particle. Therefore, in each particle of limestone (CaCO ₃ ), the reacted substance (CaO) is deposited on the outside of the particle as the reaction time elapses, and the carbon dioxide generated from the unreacted CaCO ₃ on the center side is released. , It passes through this reacted substance (CaO) and is released to the outside of the particles. Therefore, as the reaction time elapses, the reaction rate of each particle of CaCO ₃ decreases.

The reaction rate of such a decarboxylation reaction of CaCO ₃ particles is represented by the following formula (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 x ¹⁰⁸ [1 / s]
E: 2.0 x ¹⁰⁵ [J / mol]
_RG : Gas constant 8.314
T: Temperature [K]
P _All : Total pressure [atm]
P _CO2 : _CO2 partial pressure [atm]
P _{CO2_eq} : Equilibrium CO ₂ partial pressure [atm]
X: Reaction rate

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

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

Hereinafter, the control of the decarboxylation reaction in the reaction step S3 will be described.
For example, when a part of limestone powder such as cement raw material refined powder M is taken from the cement manufacturing process such as the cement manufacturing apparatus 30 shown in FIG. 1, if the carbon dioxide producing apparatus 10 is arranged close to the cement manufacturing apparatus 30. , It can be considered that the temperature of limestone does not fluctuate significantly. Therefore, since the reaction time in the reactor 13 can be regarded as constant in the fluidized bed and the like, the items to be considered are the input amount of limestone, the partial pressure of carbon dioxide, and the mixed gas G containing carbon dioxide flowing in the reactor 13. The gas temperature.

The inventors of the present invention measure the partial pressure of carbon dioxide controlled by the air supply amount of the air supply line 23 and the temperature of the mixed gas G after being heated in the first heat exchanger (heat exchanger) 12. Then, depending on the temperature, the reaction pressure or partial pressure of carbon dioxide of the decarbonation reaction, which is the production condition for maximizing the amount of carbon dioxide produced (or the concentration of carbon dioxide) at that time, and the amount of limestone powder input. Was determined based on the calculation result obtained in advance by the chemical engineering calculation, and a method for controlling the decarbonization reaction in the reactor 13 was found.
The carbon dioxide concentration can be obtained by dividing the difference between the flow rates of the mixed gas G in the recovery line 22 and the flow rate of the air supply line 23 in FIG. 1 by the flow rate of the mixed gas G in the recovery line 22.

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

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. Further, 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 the post-reaction temperature and the limestone reaction rate.

In these calculation examples, the air supply amount 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 air is used in the gas circulation line. It is set as a condition when it is circulated.

Further, 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 air and the value of the flow meter 28 that detects the recovery flow rate of the mixed gas that is low-concentration carbon dioxide. That is, this CO ₂ recovery amount is the amount of carbon dioxide produced by the decarboxylation reaction in the reactor 13.

Next, the maximum carbon dioxide production amount and the limestone input amount at that time are obtained for each temperature of the mixed gas G after being heated in the first heat exchanger (heat exchanger) 12. The values obtained by this are drawn on the graph of the limestone input amount and the maximum carbon dioxide production amount. At that time, the horizontal axis is dimensionless with the reference limestone input amount (L), and the vertical axis is the value (C / L) obtained by dividing the maximum carbon dioxide production amount C by L on a molar basis per unit time, and the air supply amount. (A) and the circulation amount (R) of the mixed gas are also expressed as (A / 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 is plotted for each temperature of the mixed gas containing carbon dioxide and (A / L). Further, FIG. 11 shows a graph of a calculation example in which the relationship between the maximum carbon dioxide production amount and the limestone input amount at that time is plotted for each temperature of the mixed gas containing carbon dioxide and (A / L). In the graphs of FIGS. 10 and 11, an approximate curve (hereinafter referred to as an isobaric line) connecting the same conditions of the air supply amount (or the circulation amount of the mixed gas) is created. In addition, an approximate curve (hereinafter referred to as an isotherm) connecting the conditions where the mixed gas temperature is the same is created.

Further, in creating the graphs shown in FIGS. 10 and 11, the limestone at 750 ° C. was mixed with the mixed gas after heat exchange flowing in the gas circulation line at 900 ° C. and 1200 L / min (converted to 0 ° C.). Assuming that the reaction time in the reactor 13 that produces a decarboxylation reaction in which the amount of carbon dioxide produced is adjusted is 10 seconds, the air supply amounts are 75 L / min, 100 L / min, 125 L / min, and 150 L / min (0, respectively). The amount of carbon dioxide produced (recovered amount) when the amount of limestone input was changed, the reaction rate of the decarboxylation reaction, and the temperature after the reaction were calculated.

Then, as shown in FIG. 12, the desired carbon dioxide production amount and the expected limestone input amount are drawn in the graph of the limestone input amount and the maximum carbon dioxide production amount (recovery amount), and are designated as points X. Let the intersections of the two isotherms and the two isotherms surrounding the point X be points A, B, C, and D.

As shown in FIG. 13, for example, 10 mag Divide into minutes. The finer the number of divisions, the higher the calculation accuracy. Then, a grid-shaped auxiliary line (one-dot chain line in FIG. 13) connecting the dividing points is created.

Then, the decarbonization reaction that satisfies the point X is performed by investigating the distance between the point X indicating the assumed amount of limestone input and the isobaric line and the isotherm line surrounding the point X, and dividing the distance according to the distance. The reaction pressure and the temperature of the mixed gas can be obtained.
If the line segments AB, BC, CD, and AD deviate significantly from the isotherms and isotherms, the calculation accuracy is improved by narrowing the intervals between the isotherms and the isotherms. be able to.

In the calculation example in the reaction step S3 shown in FIGS. 12 and 13, the circulation amount of the mixed gas is 1200 L / min, the amount of carbon dioxide produced is 34 L / min, and the amount of limestone input is 30 kg / hour. It is a calculation of the amount of air supplied.
From the plot shown in FIG. 13, it is read that the temperature of the mixed gas: (950 × 6 + 925 × 4) / 10 = 940 ° C. and the air supply amount: (125 × 8 + 150 × 2) / 10 = 130 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 is 34.2 L / min and the limestone input amount is 30.2 kg / hour, and the desired carbon dioxide production amount is 34 L. When / min and the amount of limestone input are set to 30 kg / hour, it can be calculated with errors of 0.6% and 0.7%, 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 the same as that shown in FIG. 11 by making the reference limestone input amount (L) dimensionless at 22.30 kg / hour (222.9 mol / hour). Can be done.

As shown in FIG. 14, even if the air amount is fixed and the circulation amount of the mixed gas in the gas circulation line is changed, conditions such as the amount of limestone input for obtaining the maximum carbon dioxide production amount can be obtained. ..

In the gas circulation line 11 on the downstream side of the reactor 13, the mixed gas G, quicklime generated by the decarboxylation reaction, unreacted cement raw material fine powder M remaining unreacted in the reactor 13, and the like are separated by the separator 14. Flow towards.

In such control, fluctuations in the amount of carbon dioxide produced due to fluctuations in the temperature of the high-temperature atmosphere field H and the amount of air supplied in the air supply line 23 in actual operation, and the large-scale equipment for injecting an excessive amount of limestone. Considering the cost performance with the amount of carbon dioxide produced due to the conversion, as shown in FIGS. 15 and 16, the amount of limestone input is within ± 10% of the maximum amount of carbon dioxide produced in the calculation. Since the same effect can be obtained by controlling the above, it is preferable to control the input amount of limestone so that the amount of carbon dioxide produced is within the range of the calculated maximum value ± 10%.

In the separator 14, the mixed gas (gas) G containing carbon dioxide and the powder (solid) such as fresh lime generated by the decarboxylation reaction and the unreacted cement raw material refined powder M are separated (solid air separation step). S4). The quicklime (CaO) separated by the separator 14 and the unreacted cement raw material fine powder M are discharged to the extraction duct 41 and sent to the calcining furnace 34 of the cement manufacturing apparatus 30 to be effective as the cement raw material fine powder M. It will be used.

The temperature of the mixed gas G separated by solid air through the separator 14 is about 750 ° C., and if the mixed gas G enters the circulation pump 16 on the downstream side of the gas circulation line 11 as it is, the circulation pump 16 may be damaged by heat. In the present 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 flows through the gas circulation line 11 whose temperature has dropped to about 300 ° C. on the downstream side of the connection position of the carbon dioxide recovery line 22. Heat exchange with gas G.

As a result, the temperature of the mixed gas G flowing into the circulation pump 16 drops to, for example, about 300 ° C., and damage or deterioration due to heat of the circulation pump 16 is prevented. On the other hand, the mixed gas G flowing into the first heat exchanger 12 due to circulation is heated to, for example, about 600 ° C. by the second heat exchanger 15, and the mixed gas G is raised to about 850 ° C. in the first heat exchanger 12. Helps to raise the temperature reliably.
The second heat exchanger 15 does not necessarily have to be provided, and may 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.

A part of the mixed gas G containing carbon dioxide that has passed through the circulation pump 16 is recovered from the carbon dioxide recovery line 22 connected to the gas circulation line 11 to the outside of the gas circulation line 11 (recovery step S5). If the concentration of the mixed gas G recovered via the carbon dioxide recovery line 22 is excessive, for example, in the growth of plants and algae, the concentration is further increased to 1 vol% or more and 50 vol% or less, for example, 5 vol% by using air after recovery. It can also be adjusted.

In this recovery step S5, the amount of the mixed gas G containing carbon dioxide recovered through the carbon dioxide recovery line 22 (recovery amount per unit time) is, for example, the decarboxylation of the cement raw material refined powder M in the reactor 13. The amount of carbon dioxide produced by the reaction (production amount per unit time) is adjusted to be the same as the total amount of the air supply amount of the air supply line 23. As a result, the flow rate and pressure of the mixed gas G circulating in the gas circulation line 11 can be kept constant.

After that, the mixed gas G not 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-mentioned steps are repeated from the air supply step S1 again.

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 is circulated in the gas circulation line 11 and air is circulated from the air 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 heat the cement raw material refined powder (produced raw material powder) M supplied to the gas circulation line to remove carbon dioxide. By causing a carbon dioxide reaction, low-concentration carbon dioxide (mixed gas G) having a concentration of 1 vol% or more and 50 vol% or less can be continuously and efficiently generated.
The obtained low-concentration carbon dioxide is generated at a concentration higher than that in consideration of the usage, for example, the concentration required for growing plants in a plant factory or growing algae in a green oil manufacturing plant. If so, it may be further diluted with air or the like after being produced.

Then, when the decarbonation reaction is performed, air is supplied to the gas circulation line 11 to reduce the partial pressure of carbon dioxide contained in the mixed gas, so that the temperature is close to 900 ° C. as in the decarbonation reaction in an atmospheric pressure environment. Since it is not necessary to raise the temperature to a high temperature, the mixed gas G is heated using the high temperature atmosphere field H of the cement manufacturing apparatus having a maximum temperature of about 800 to 850 ° C., and the mixed gas is used as a heat source to lower the pressure from the cement raw material refined powder M. It is possible to generate a concentration of carbon dioxide at low cost.

Further, according to the present invention, since carbon dioxide generated by burning fossil fuels such as coal, oil, and natural gas is not contained as a source of mixed gas G containing carbon dioxide, the volatileness contained in these combustion exhaust gas. Efficiently uses low-concentration carbon dioxide applicable to the growth of plants and algae without fear of containing impurities that are harmful to humans and plants such as organic compounds (VOC), carbon monoxide, nitrogen oxides, and sulfur oxides. Can be manufactured.

Further, the first heat exchanger (heat exchanger) for heating the mixed gas G, which is a heat source for causing the limestone contained in the cement raw material fine powder M to undergo a decarbonation reaction, includes cement raw material fine powder containing the limestone and the like. Since the solid (powder) does not flow in, these solids (powder) do not adhere to the first heat exchanger and block the flow path, and stable low-concentration carbon dioxide can be produced at low maintenance cost. can do.

According to the carbon dioxide production method of the present invention, the maximum value of carbon dioxide produced in the reaction step is ± 10 based on the amount of air supplied to the gas circulation line and the temperature of the mixed gas after being heated in the heating step. By controlling the supply amount of the produced raw material powder to the gas circulation line so as to be within the range of%, it is possible to generate carbon dioxide having a low concentration as efficiently as possible. As a result, low-concentration carbon dioxide can be produced in large quantities at low cost.

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

Specifically, in designing the carbon dioxide production device, in the above-mentioned carbon dioxide production method, for example, the capacity of a pump for supplying air in the air supply line and the mixed gas in the first heat exchanger (heat exchanger). Carbon dioxide that maximizes the production efficiency of low-concentration carbon dioxide, such as selecting the high-temperature atmosphere field H for installing the first heat exchanger by setting the heating temperature required for heat exchange. Manufacturing equipment can be designed.

Although some embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and variations thereof are included in the scope of the invention described in the claims and the equivalent scope thereof, as are included in the scope and gist of the invention.

10 ... Carbon dioxide production equipment 11 ... Gas circulation line 12 ... First 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 ... Air supply line 25 ... Reaction vessel 31 ... Preheater 32 ... Cement kiln 33 ... Cleaner cooler 34 ... Temporary furnace E ... Air G ... Mixed gas H ... High temperature atmosphere field M ... Cement raw material refined powder

Claims (6)

A gas circulation line that circulates a mixed gas containing carbon dioxide and air, a heat exchanger, a reactor, and a separator arranged in order in the gas circulation line, and a raw material powder supply connected to the gas circulation line. Equipped with a line, a carbon dioxide recovery line, and an air supply 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 supplies carbon dioxide-producing raw material powder to the gas circulation line between the reactor and the heat exchanger or connected to the reactor.
In the reactor, the generated raw material powder is brought into contact with the mixed gas heated by the heat exchanger to generate carbon dioxide by a decarboxylation reaction.
The separator separates the produced 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 air supply line is a carbon dioxide production apparatus characterized in that air is supplied to the gas circulation line. The high temperature atmosphere field includes at least one of a cement kiln, a clinker cooler, a preheater, a calciner, and an air extraction duct connecting the clinker cooler and the calciner in a cement manufacturing apparatus. The carbon dioxide production apparatus according to claim 1. Further provided with a return line for returning the produced raw material powder separated by the separator to at least one of the cement kiln, the preheater, the calcining furnace, and the bleeding duct. 2. The carbon dioxide producing apparatus according to claim 2. A method for producing carbon dioxide using the carbon dioxide producing apparatus according to any one of claims 1 to 3.
An air supply process for supplying air to the gas circulation line via the air supply line, and
A heating step of heating the mixed gas with the heat exchanger,
A reaction step of directly contacting the produced raw material powder with the mixed gas heated in the heating step to heat the mixture to cause a decarboxylation reaction to generate carbon dioxide.
A solid air separation step for separating the produced raw material powder and the mixed gas,
It is characterized by comprising a recovery step of recovering the mixed gas containing the carbon dioxide in an amount corresponding to the amount of carbon dioxide produced in the reaction step and returning the remaining mixed gas to the gas circulation line. Carbon dioxide production method. In the reaction step, the amount of carbon dioxide produced is within the range of the maximum value ± 10% based on the amount of air supplied in the air supply step and the temperature of the mixed gas after being heated in the heating step. The carbon dioxide production method according to claim 4, wherein the amount of the produced raw material powder supplied to the gas circulation line is controlled. The method for designing a carbon dioxide producing apparatus according to any one of claims 1 to 3.
Based on the amount of air 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 range of the maximum value ± 10%. A method for designing a carbon dioxide production apparatus, which comprises determining a supply amount of the produced raw material powder to the gas circulation line and designing the carbon dioxide production apparatus based on the determination.

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