CO2 recovery system for cement manufacturing facilities and CO2 recovery method for cement manufacturing facilities

Abstract

To provide a CO2 recovery system of a cement manufacturing plant which can efficiently recover CO2 of a raw material source and CO2 of a fuel source.SOLUTION: A CO2 recovery system of a cement manufacturing plant includes: a combustion exhaust gas pipe 30 which has a kiln 10 for cement manufacture and an indirect heating type calcining furnace 20, and allows exhaust gas containing combustion exhaust gas discharged from the indirect heating type calcining furnace 20 to flow therein; an exhaust gas heat exchanger 40 having a suction port connected to the combustion exhaust gas pipe 30, and an exhaust port; a reaction device 50 which has an exhaust gas introduction port connected to the exhaust port of the exhaust gas heat exchanger 40, a calcium oxide introduction port, a calcium carbonate take-out port and an exhaust gas discharge port, brings the exhaust gas introduced from the gas introduction port into contact with the calcium oxide introduced from the calcium oxide introduction port, thereby reacts CO2 in the exhaust gas with the calcium oxide and generates calcium carbonate; and a conveyance device for conveying the calcium carbonate taken out of the calcium carbonate take-out port of the reaction device 50 to a raw material introduction port of the indirect heating type calcining furnace 20.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a CO2 recovery system for cement manufacturing equipment and a method for recovering CO2 from cement manufacturing equipment.

Background Art

[0002] In cement manufacturing equipment, a large amount of CO2 is generated during cement production. The CO2 generated during cement production includes CO2 of raw material origin and CO2 of fuel origin. The CO2 of raw material origin is the CO2 generated by the thermal decomposition of calcium carbonate (limestone), which is the main component of cement raw materials, to produce calcium oxide (quicklime). The CO2 of fuel origin is the CO2 in the exhaust gas of combustion gas used as a heat source when firing cement raw materials.

[0003] In order to reduce the CO2 emission amount of cement manufacturing equipment, a system for recovering CO2 generated during cement production has been studied. As a system capable of efficiently recovering CO2 of raw material origin, a system has been studied in which a heat medium heated to a temperature higher than the thermal decomposition temperature of calcium carbonate using combustion gas and cement raw materials are mixed in a calcination furnace, and the CO2 of raw material origin generated by heating and calcining the cement raw materials is recovered (Patent Documents 1 and 2). Patent Document 1 describes that the exhaust gas of combustion gas (combustion exhaust gas) used for heating the heat medium and cement raw materials are supplied to a preheater to preheat the cement raw materials with the combustion exhaust gas. Further, Patent Document 2 describes that after cooling a part of the calcined cement raw materials with a heat exchanger, returning them to the preheater, and bringing the cement raw materials into contact with the combustion exhaust gas, the fuel-origin CO2 in the combustion exhaust gas is absorbed by calcium oxide in the cement raw materials.

Prior Art Documents

[0005] In the cement manufacturing equipment described in Patent Document 1, the cement raw materials are preheated with combustion exhaust gas, thus allowing for effective utilization of the heat source in the cement manufacturing equipment. However, because the combustion exhaust gas is at a high temperature, when the cement raw materials are preheated with combustion exhaust gas, some of the calcium carbonate may decompose thermally, generating CO2 originating from the raw materials within the preheater. Furthermore, in the cement manufacturing equipment described in Patent Document 2, the reaction heat generated by the reaction between calcium oxide and CO2 in the combustion exhaust gas further increases the temperature of the combustion exhaust gas, which suppresses the reaction between calcium oxide and CO2, potentially making it difficult to absorb CO2 originating from the fuel into the calcium oxide.

[0006] This invention has been made in view of the circumstances described above, and aims to provide a CO2 recovery system for cement manufacturing equipment and a CO2 recovery method for cement manufacturing equipment that can efficiently recover CO2 originating from raw materials and CO2 originating from fuel. [Means for solving the problem]

[0007] To solve the above problems, the CO2 recovery system for a cement manufacturing facility according to Embodiment 1 of the present invention is a CO2 recovery system for a cement manufacturing facility having a cement manufacturing kiln and an indirect heating type calcination furnace that includes a raw material inlet, a calcined material outlet, and a CO2 outlet, and indirectly calcines cement raw materials introduced from the raw material inlet using combustion gas to produce calcined cement raw materials and CO2, wherein the exhaust gas heat exchanger has a combustion exhaust gas pipe through which exhaust gas containing combustion exhaust gas discharged from the indirect heating type calcination furnace flows, an intake port connected to the combustion exhaust gas pipe, and an exhaust port. The configuration includes an exhaust gas inlet connected to the exhaust port of the exhaust gas heat exchanger, a calcium oxide inlet, a calcium carbonate outlet, and a gas outlet, and a reaction device that generates calcium carbonate by bringing the exhaust gas introduced from the exhaust gas inlet into contact with the calcium oxide introduced from the calcium oxide inlet, thereby reacting the CO2 in the combustion exhaust gas with the calcium oxide, and a conveying device that conveys the calcium carbonate taken out from the calcium carbonate outlet of the reaction device to the raw material inlet of the indirect heating type calcination furnace.

[0008] According to the CO2 recovery system for cement manufacturing equipment of Embodiment 1 of the present invention, which is configured in this way, cement raw materials are indirectly calcined in an indirectly heated calcination furnace using combustion gas to generate calcined cement raw materials and CO2, thereby generating a high concentration of CO2 in the indirectly heated calcination furnace. Furthermore, in the reaction device, the CO2 in the combustion exhaust gas is reacted with calcium oxide to produce calcium carbonate, and the produced calcium carbonate is supplied to the indirectly heated calcination furnace by a conveying device, thereby recovering the CO2 in the combustion exhaust gas. Moreover, after the temperature of the combustion exhaust gas is reduced using an exhaust gas heat exchanger, the reaction between calcium oxide and CO2 in the reaction device is promoted, thereby accelerating the reaction between CO2 and calcium oxide in the reaction device. As a result, the CO2 recovery efficiency in the combustion exhaust gas is improved. Therefore, according to the CO2 recovery system for cement manufacturing equipment of the present invention, both CO2 originating from raw materials and CO2 originating from fuel can be efficiently recovered. Furthermore, the amount of combustion gas used can be reduced by utilizing the heat generated by the reaction between calcium oxide and CO2 in the combustion exhaust gas for preheating cement raw materials, etc.

[0009] Aspect 2 of the present invention is a CO2 recovery system for a cement manufacturing facility according to aspect 1, wherein the system has piping that transports kiln exhaust gas discharged from the cement manufacturing kiln to the intake port of the exhaust gas heat exchanger. According to the CO2 recovery system for cement manufacturing equipment of embodiment 2 of the present invention, CO2 in the combustion exhaust gas discharged from the indirectly heated calcination furnace, as well as CO2 in the kiln exhaust gas discharged from the cement manufacturing kiln, can be recovered. Furthermore, the amount of combustion gas used can be further reduced by utilizing the reaction heat generated by reacting the CO2 in the kiln exhaust gas with calcium oxide for preheating cement raw materials, etc.

[0010] A third aspect of the present invention is a CO2 recovery system for a cement manufacturing facility according to aspect 1 or aspect 2, wherein the cement raw material calcined material contains calcium oxide, and the system is configured to have a first transport path for transporting the cement raw material calcined material, which has been removed from the calcined material outlet of the indirect heating type calcination furnace, to the cement manufacturing kiln, and a second transport path for transporting it to the calcium oxide inlet of the reaction apparatus. According to the CO2 recovery system for cement manufacturing equipment of embodiment 3 of the present invention, CO2 can be recovered from the combustion exhaust gas using calcined cement raw material. Furthermore, it becomes easier to adjust the amount of calcium oxide that comes into contact with the CO2 in the combustion exhaust gas.

[0011] A fourth aspect of the present invention is a CO2 recovery system for a cement manufacturing facility according to the third aspect, wherein a cooler is located in the second transport path. According to the CO2 recovery system for cement manufacturing equipment of embodiment 4 of the present invention, the temperature of the calcium oxide that comes into contact with the combustion exhaust gas discharged from the indirectly heated calcination furnace can be lowered. Therefore, even if reaction heat is generated by the reaction of CO2 in the combustion exhaust gas with calcium oxide, the temperature of the resulting calcium carbonate can be maintained at a predetermined temperature. As a result, the temperature of the combustion exhaust gas is less likely to rise, and CO2 in the combustion exhaust gas can be recovered with higher efficiency.

[0012] Aspect 5 of the present invention is a CO2 recovery system for a cement manufacturing facility according to aspect 3 or aspect 4, which includes a calcium oxide quantity control device that controls the amount of the calcined cement raw material to be transported to the cement manufacturing kiln and the amount of the calcined cement raw material to be transported to the calcium oxide inlet of the reaction device. According to the CO2 recovery system for cement manufacturing equipment of embodiment 5 of the present invention, it is possible to adjust the amount of calcium oxide transported to the reactor, so that the amount of calcium oxide necessary to recover CO2 from the combustion exhaust gas can be supplied to the reactor. Therefore, CO2 from the combustion exhaust gas can be recovered with even higher efficiency.

[0013] Aspect 6 of the present invention is a CO2 recovery system for a cement manufacturing facility according to aspect 5, wherein the calcium oxide amount control device is configured to adjust the amount of calcium oxide to be transported to the calcium oxide inlet of the reactor based on either or both of the CO2 concentration of the gas introduced from the exhaust gas inlet of the reactor and the CO2 concentration of the gas exhausted from the gas outlet of the reactor. According to the CO2 recovery system for cement manufacturing equipment of embodiment 6 of the present invention, the amount of calcium oxide necessary to recover CO2 from the combustion exhaust gas can be reliably supplied to the reactor. Therefore, CO2 from the combustion gas can be recovered with even higher efficiency.

[0014] Aspect 7 of the present invention relates to a CO2 recovery system for a cement manufacturing facility according to aspect 5 or aspect 6, wherein the reaction apparatus The gas outlet The system is configured to adjust the amount of calcium oxide transported to the calcium oxide inlet of the reactor based on either or both of the temperature of the exhaust gas, the temperature of the calcium carbonate taken out from the calcium carbonate outlet, and / or the temperature of the calcium oxide transported from the calcium carbonate outlet. According to the CO2 recovery system for cement manufacturing equipment of embodiment 7 of the present invention, the amount of calcium oxide necessary to recover CO2 from the combustion exhaust gas can be reliably supplied to the reactor. Therefore, CO2 from the combustion gas can be recovered with even higher efficiency.

[0015] Aspect 8 of the present invention is a CO2 recovery system for a cement manufacturing facility according to aspect 7, wherein the calcium oxide amount control device is configured to further adjust the amount of calcium oxide to be transported to the calcium oxide inlet of the reactor based on the temperature of the gas introduced from the exhaust gas inlet of the reactor, the temperature of the calcium oxide introduced into the calcium oxide inlet of the reactor, or both. According to the CO2 recovery system for cement manufacturing equipment of embodiment 8 of the present invention, the amount of calcium oxide necessary to recover CO2 from the combustion exhaust gas can be supplied to the reactor more reliably. Therefore, CO2 from the combustion gas can be recovered with even higher efficiency.

[0016] Aspect 9 of the present invention relates to a CO2 recovery system for a cement manufacturing facility in any one of aspects 1 to 8, wherein the exhaust gas heat exchanger is a preheater including a cement raw material inlet and a solid-gas separation device for separating the cement raw material supplied from the cement raw material inlet from the combustion exhaust gas, and the preheater is configured to have a cement raw material quantity control device for controlling the amount of cement raw material supplied from the cement raw material inlet of the preheater. According to the CO2 recovery system for cement manufacturing equipment of embodiment 9 of the present invention, the cement raw materials are preheated with the heat of the combustion exhaust gas, so the amount of heat used when indirectly heating the cement raw materials, i.e., the amount of combustion gas used, can be reduced. Therefore, the amount of CO2 generated from fuel can be reduced.

[0017] Aspect 10 of the present invention is a CO2 recovery system for a cement manufacturing facility, one of the embodiments 1 to 9, wherein the reaction apparatus has a cooling unit. According to the CO2 recovery system for cement manufacturing equipment of embodiment 10 of the present invention, the reaction between CO2 and calcium oxide in the reactor is promoted by lowering the temperature inside the reactor using a cooling unit. Therefore, the recovery efficiency of CO2 in the combustion exhaust gas is improved.

[0018] Aspect 11 of the present invention is a CO2 recovery system for a cement manufacturing facility according to aspect 10, wherein the cooling unit is a boiler that generates steam by the absorption of heat from water. According to the CO2 recovery system for cement manufacturing equipment of embodiment 11 of the present invention, the temperature inside the reaction apparatus can be efficiently reduced.

[0019] Aspect 12 of the present invention is a CO2 recovery system for a cement manufacturing facility in any one of aspects 1 to 11, which is configured to include a pressure reducing device for reducing the internal pressure of the indirectly heated calcination furnace. According to the CO₂ recovery system of the cement manufacturing equipment of Aspect 12 of the present invention, by reducing the internal pressure of the indirectly heated calciner, the thermal decomposition temperature of calcium carbonate in the indirectly heated calciner can be lowered. As a result, the amount of heat when indirectly heating the cement raw material, that is, the amount of combustion gas used, can be reduced. Therefore, the amount of CO₂ generated from the fuel source can be reduced. Furthermore, the temperature of the combustion exhaust gas discharged from the indirectly heated calciner can be lowered, and generation of CO₂ from the raw material source in the exhaust gas heat exchanger can be suppressed.

[0020] Aspect 13 of the present invention is configured to have a pressurizing device that pressurizes the internal pressure of the reaction device in the CO₂ recovery system of the cement manufacturing equipment according to any one of Aspects 1 to 12. According to the CO₂ recovery system of the cement manufacturing equipment of Aspect 13 of the present invention, by pressurizing the internal pressure of the reaction device, the thermal decomposition temperature of calcium carbonate can be increased. As a result, the reaction between CO₂ and calcium oxide in the combustion exhaust gas is promoted, and CO₂ in the combustion exhaust gas can be recovered with even higher efficiency.

[0021] Aspect 14 of the present invention is configured to have a pipe that conveys the CO₂-containing gas generated by other devices except the cement manufacturing kiln and the indirectly heated calciner to the intake port of the exhaust gas heat exchanger or the exhaust gas inlet of the reaction device in the CO₂ recovery system of the cement manufacturing equipment according to any one of Aspects 1 to 13. According to the CO₂ recovery system of the cement manufacturing equipment of Aspect 14 of the present invention, CO₂ generated by other devices except the cement manufacturing kiln and the indirectly heated calciner can be efficiently recovered, and CO₂ emitted into the atmosphere can be reduced.

[0022] A CO2 recovery method for a cement manufacturing facility according to aspect 15 of the present invention is a CO2 recovery method for a cement manufacturing facility having a cement manufacturing kiln and an indirectly heated calcination furnace equipped with a raw material inlet, a calcined material outlet, and a CO2 outlet, comprising: a CO2 recovery step of indirectly heating and calcining cement raw materials introduced from the raw material inlet of the indirectly heated calcination furnace using combustion gas to generate calcined cement raw materials and CO2, and recovering the CO2; a cooling step of introducing the combustion exhaust gas discharged from the indirectly heated calcination furnace into an exhaust gas heat exchanger to cool it to 450°C or below; a calcium carbonate generation step of contacting the combustion exhaust gas cooled to 450°C or below with calcium oxide to react the CO2 in the combustion exhaust gas with the calcium oxide to generate calcium carbonate; and a calcium carbonate supply step of supplying the calcium carbonate to the raw material inlet of the indirectly heated calcination furnace.

[0023] According to the CO2 recovery method for cement manufacturing equipment of embodiment 15 of the present invention, which is configured in this way, in the CO2 recovery step, cement raw materials are indirectly calcined using combustion gas to generate calcined cement raw materials and CO2, so that a high concentration of CO2 can be generated in the indirect heating type calcination furnace. Furthermore, in the calcium carbonate generation step, CO2 in the combustion exhaust gas is reacted with calcium oxide to generate calcium carbonate, and in the calcium carbonate supply step, the generated calcium carbonate is supplied to the indirect heating type calcination furnace by a conveying device, so that CO2 in the combustion exhaust gas can be recovered. Moreover, in the cooling step, the temperature of the combustion exhaust gas is reduced to 450°C or below using an exhaust gas heat exchanger, and then in the calcium carbonate generation step, CO2 in the combustion exhaust gas is reacted with calcium oxide, so that the reaction between CO2 and calcium oxide is promoted. Therefore, the CO2 recovery efficiency of the combustion exhaust gas is improved. Accordingly, according to the CO2 recovery method for cement manufacturing equipment of embodiment 13, both CO2 originating from raw materials and CO2 originating from fuel can be efficiently recovered. Furthermore, by utilizing the heat generated by the reaction between calcium oxide and CO2 in the combustion exhaust gas for preheating cement raw materials, the amount of heat (combustion gas used) required for indirect heating of the cement raw materials can be reduced. Therefore, the amount of CO2 generated from the fuel can be reduced.

[0024] Aspect 16 of the present invention is a method for recovering CO2 from a cement manufacturing facility according to aspect 15, wherein, before introducing the combustion gas into the exhaust gas heat exchanger, a mixing step is included in which the combustion exhaust gas and the exhaust gas generated in the cement manufacturing kiln are mixed to produce a mixed exhaust gas, and in the cooling step, the mixed exhaust gas is cooled to 450°C or below. According to the CO2 recovery method for cement manufacturing equipment of embodiment 16 of the present invention, CO2 in the exhaust gas of the cement manufacturing kiln can be recovered along with CO2 in the combustion exhaust gas. Furthermore, by using the reaction heat generated by reacting CO2 in the exhaust gas of the cement manufacturing kiln with calcium oxide, the amount of heat used when indirectly heating the cement raw materials (amount of combustion gas used) and the amount of combustion gas used in the cement manufacturing kiln can be reduced. Therefore, the amount of CO2 generated from fuel can be reduced. [Effects of the Invention]

[0025] According to the present invention, it is possible to provide a CO2 recovery system for cement manufacturing equipment and a CO2 recovery method for cement manufacturing equipment that can efficiently recover CO2 originating from raw materials and CO2 originating from fuel. [Brief explanation of the drawing]

[0026] [Figure 1] This is a schematic diagram showing a CO2 recovery system for a cement manufacturing facility according to the first embodiment of the present invention. [Figure 2] This is a schematic diagram showing a CO2 recovery system for a cement manufacturing facility according to a second embodiment of the present invention. [Modes for carrying out the invention]

[0027] The following describes a CO2 recovery system for a cement manufacturing facility and a CO2 recovery method for a cement manufacturing facility according to one embodiment of the present invention, with reference to the drawings. The embodiments described below are provided specifically to better illustrate the spirit of the invention and do not limit the present invention unless otherwise specified. Furthermore, the drawings used in the following description may be enlarged for convenience to clearly illustrate the features of the present invention, and the dimensional ratios of each component may not be the same as in reality.

[0028] (First Embodiment) Figure 1 is a schematic diagram showing a CO2 recovery system for a cement manufacturing facility according to the first embodiment of the present invention. In Figure 1, solid arrows schematically represent the flow of matter, and dashed arrows schematically represent the flow of gas. As shown in Figure 1, the CO2 recovery system 101 of the cement manufacturing facility includes a cement manufacturing kiln 10 and an indirect heating type calcination furnace 20.

[0029] The cement manufacturing kiln 10 comprises a rotatable cylindrical furnace body 11 and a main burner 12 that heats the inside of the furnace body 11. The furnace body 11 has a cement raw material calcined material introduction section at one end and a cement clinker removal section at the other end. The cement clinker removal section is connected to a clinker cooler 13. The clinker cooler 13 has a cooling device such as a cooling fan. The cement manufacturing kiln 10 generates cement clinker and CO2 by firing the cement raw material calcined material using the main burner 12. The generated CO2 originating from the raw materials and the exhaust gas from the main burner 12 are removed through a kiln exhaust gas pipe 14. The clinker cooler 13 cools the cement clinker by heat exchange with air. High-temperature air CG obtained when the cement clinker is cooled is removed from the clinker cooler 13.

[0030] The indirectly heated calcination furnace 20 has a raw material inlet at the bottom and a calcined material outlet at the top. The calcined material outlet is connected to the calcined material outlet pipe 21. The indirectly heated calcination furnace 20 also has a combustion gas pipe 23 through which combustion gas flows. The combustion gas exhaust port of the combustion gas pipe 23 is connected to the combustion exhaust gas pipe 30, and the other end of the combustion exhaust gas pipe 30 is connected to the solid-gas separator 31. The solid-gas separator 31 is connected to the kiln exhaust gas pipe 14 and the exhaust gas heat exchanger 40. The exhaust gas heat exchanger 40 is connected to the reactor 50. The reactor 50 is connected to the reaction product gas heat exchanger 60.

[0031] The indirect heating type calcination furnace 20 heats and calcines the cement raw materials using the heat of the combustion gas flowing through the combustion gas pipe 23, producing calcined cement raw material and CO2. As a cement raw material, for example, a mixed powder whose main component is limestone (calcium carbonate) and which also contains clay components (SiO2, Al2O3, Fe2O3) can be used. By heating and calcining this cement raw material, some or all of the limestone in the cement raw material decomposes thermally, producing calcined cement raw material containing calcium oxide and CO2.

[0032] The calcined material removal pipe 21 is a pipe for removing the calcined cement raw material and CO2 generated in the indirect heating calcination furnace 20 to the outside. The calcined material removal pipe 21 is connected to the solid-gas separator 22. The solid-gas separator 22 separates the calcined cement raw material and CO2. For example, a cyclone can be used as the solid-gas separator 22. The gas outlet of the solid-gas separator 22 is connected to the intake port (pipe 72a) of the CO2 heat exchanger 70. The calcined cement raw material outlet of the solid-gas separator 22 is connected to the transport path A.

[0033] The CO2 heat exchanger 70 has three solid-gas separators 71a, 71b, and 71c arranged in series vertically, and piping 72a, 72b, and 72c connecting the solid-gas separators 71a, 71b, and 71c. The uppermost solid-gas separator 71c is connected to an exhaust CO2 pipe 72d. A blower 73 is located on the exhaust CO2 pipe 72d. The piping 72c between the uppermost solid-gas separator 71c and the middle solid-gas separator 71b has a cement raw material inlet. The amount of cement raw material input is controlled by a cement raw material quantity control device. The solid material outlet of the lowermost solid-gas separator 71a is connected to a transport path E. The transport path E is connected to the raw material inlet of the indirect heating type calcination furnace 20. For example, cyclones can be used as the solid-gas separators 71a, 71b, and 71c. The CO2 heat exchanger 70 acts as a preheater to preheat the cement raw materials by bringing them into contact with CO2 introduced from the cement raw material inlet.

[0034] As transport route A, a device used as a transport device for cement raw materials, such as a pipeline, can be used. Transport route A is connected to a calcium oxide amount control device 55. The calcium oxide amount control device 55 is connected to a first transport route A1 and a second transport route A2. The first transport route A1 is a transport route that transports the calcined cement raw material to the cement manufacturing kiln 10. The second transport route A2 is a transport route that transports the calcined cement raw material to the reaction apparatus 50. The calcium oxide amount control device 55 controls the amount of calcined cement raw material transported to the cement manufacturing kiln 10 and the amount of calcined cement raw material transported to the calcium oxide inlet of the reaction apparatus 50.

[0035] The calcium oxide quantity control device 55 may adjust the amount of calcium oxide transported to the calcium oxide inlet of the reactor 50 based on either or both of the CO2 concentration of the gas introduced from the gas inlet (reaction tube 51) of the reactor 50 and the CO2 concentration of the gas exhausted from the gas outlet (solid-gas separator 52) of the reactor 50. Alternatively, the device may be configured to adjust the amount of calcium oxide transported to the calcium oxide inlet of the reactor 50 based on either or both of the temperature of the gas exhausted from the gas outlet of the reactor 50 and the temperature of the calcium carbonate taken out from the calcium carbonate outlet. Furthermore, the device may be configured to adjust the amount of calcium oxide transported to the calcium oxide inlet of the reactor 50 based on either or both of the temperature of the gas introduced from the exhaust gas inlet of the reactor 50 and the temperature of the calcium oxide introduced into the calcium oxide inlet of the reactor 50.

[0036] A cooler 56 for cooling the calcined cement raw material is located in the second transport path A2. The cooler 56 may also be a heat exchanger.

[0037] The combustion gas pipe 23 heats the inside of the indirectly heated calcination furnace 20 by generating combustion gas through the combustion of a mixed gas containing fuel gas supplied from the outside and combustion air. In this embodiment, natural gas is used as the fuel gas, and high-temperature air CG taken from the clinker cooler 13 is used as the combustion air. As the combustion gas, high-temperature combustion gas generated by burning fuels such as natural gas, petroleum, or coal in another combustion furnace can be used.

[0038] The combustion exhaust gas pipe 30 supplies the exhaust gas (combustion exhaust gas) sent from the combustion gas pipe 23 to the solid-gas separator 31.

[0039] The solid-gas separator 31 has a combustion exhaust gas inlet connected to the combustion exhaust gas pipe 30, a calcium carbonate outlet, a solids outlet, and a gas outlet. The reaction apparatus 50 also has a kiln exhaust gas inlet connected to the kiln exhaust gas pipe 14. The solid-gas separator 31 mixes the combustion exhaust gas and the kiln exhaust gas to produce a mixed exhaust gas. The solid-gas separator 31 mixes the combustion exhaust gas and the kiln exhaust gas to produce a mixed exhaust gas, and separates the mixed exhaust gas from the solids contained in the mixed exhaust gas. The gas outlet of the solid-gas separator 31 is connected to the intake port (piping 42a) of the exhaust gas heat exchanger 40. The solids outlet of the solid-gas separator 31 is connected to the transport path B. The transport path B is connected to the raw material inlet of the indirectly heated calcination furnace 20.

[0040] The exhaust gas heat exchanger 40 has three solid-gas separators 41a, 41b, and 41c arranged in series in the vertical direction, and piping 42a, 42b, and 42c connecting the solid-gas separators 41a, 41b, and 41c. The uppermost solid-gas separator 41c is connected to the reactor 50. A cement raw material inlet is provided in the piping 42c between the uppermost solid-gas separator 41c and the middle solid-gas separator 41b. The amount of cement raw material input is controlled by a cement raw material quantity control device. The cement raw material extracted from the solid material outlet of the lowermost solid-gas separator 41a is transported to the kiln exhaust gas pipe 14. For example, cyclones can be used as the solid-gas separators 41a, 41b, and 41c. The exhaust gas heat exchanger 40 acts as a preheater to preheat the cement raw material by bringing the cement raw material introduced from the cement raw material inlet into contact with the mixed exhaust gas. The exhaust port of the exhaust gas heat exchanger 40 is connected to the gas inlet (reaction tube 51) of the reaction apparatus 50.

[0041] The reaction apparatus 50 includes a reaction tube 51 having an exhaust gas inlet and a solid-gas separator 52 connected to the reaction tube 51. The reaction tube 51 is equipped with a blower 53. The reaction tube 51 has a cement raw material calcined material inlet connected to the second transport path A2. In the reaction tube 51, the mixed exhaust gas sent by the blower 53 comes into contact with the cement raw material calcined material sent from the second transport path A2. As a result, the CO2 in the mixed exhaust gas reacts with the calcium oxide in the cement raw material calcined material to produce a reaction product gas from which calcium carbonate and CO2 have been removed.

[0042] The solid-gas separator 52 separates the calcium carbonate and reaction product gas generated in the reaction tube 51 into solid and gas phases. For example, a cyclone can be used as the solid-gas separator 52. The solid-gas separator 52 has a reaction product gas outlet and a calcium carbonate outlet. The reaction product gas outlet is connected to the mixed exhaust gas intake (piping 62a) of the reaction product gas heat exchanger 60. The calcium carbonate outlet is connected to the transport path C. The transport path C is connected to the raw material inlet of the indirect heating type calcination furnace 20.

[0043] The reaction product gas heat exchanger 60 has three solid-gas separators 61a, 61b, and 61c arranged in series in the vertical direction, and piping 62a, 62b, and 62c connecting the solid-gas separators 61a, 61b, and 61c. The uppermost solid-gas separator 61c is connected to an exhaust gas pipe 62d. A blower 63 is located in the exhaust gas pipe 62d. The piping 62c between the uppermost solid-gas separator 61c and the middle solid-gas separator 61b is equipped with a cement raw material inlet. The amount of cement raw material input is controlled by a cement raw material quantity control device. The solid material outlet of the lowermost solid-gas separator 61a is connected to a transport path D. Transport path D is connected to a transport path C. For example, cyclones can be used as the solid-gas separators 61a, 61b, and 61c. The reaction product gas heat exchanger 60 acts as a preheater to preheat the cement raw materials by bringing them into contact with the reaction product gas introduced from the cement raw material inlet.

[0044] Next, a method for recovering CO2 and a method for manufacturing cement using the CO2 recovery system 101 of the cement manufacturing facility according to the first embodiment will be described. The CO2 recovery method comprises a CO2 recovery step, a cooling step, a calcium carbonate production step, and a calcium carbonate supply step.

[0045] In the CO2 recovery process, cement raw materials introduced from the raw material inlet of the indirect heating type calcination furnace 20 are indirectly heated and calcined using combustion gas to produce calcined cement raw material and CO2. The cement raw materials include preheated cement raw materials delivered to the raw material inlet via transport paths B, D, and E, and calcium carbonate transported via transport path C. The CO2 recovery process is carried out in the indirect heating type calcination furnace 20. In this embodiment, combustion gas is generated in the combustion gas pipe 23 of the indirect heating type calcination furnace 20 by burning a mixed gas containing fuel gas and combustion air, thereby raising the temperature inside the indirect heating type calcination furnace 20, and heating and calcining the cement raw materials to produce calcined cement raw material and CO2. By using the indirect heating type calcination furnace 20, the cement raw materials can be calcined without contacting them with the combustion gas. Therefore, the only gas generated inside the indirect heating type calcination furnace 20 is CO2, and the CO2 concentration inside the indirect heating type calcination furnace 20 is 100% or close to it.

[0046] The temperature inside the indirectly heated calcination furnace 20 is the temperature at which calcium carbonate contained in the cement raw material decomposes to produce calcium oxide. The temperature at which calcium carbonate decomposes varies depending on the pressure inside the indirectly heated calcination furnace 20. As the pressure inside the indirectly heated calcination furnace 20 decreases, the temperature at which calcium carbonate decomposes also decreases. One way to lower the pressure inside the indirectly heated calcination furnace 20 is to use a pressure-reducing type blower 73. The temperature inside the indirectly heated calcination furnace 20 is, for example, between 700°C and 1000°C.

[0047] CO2 generated in the indirectly heated calcination furnace 20 is sent to the CO2 heat exchanger 70 through the calcination material removal pipe 21 and the solid-gas separator 22. In the CO2 heat exchanger 70, the CO2 and cement raw materials come into contact, transferring heat from the CO2 to the cement raw materials, preheating the cement raw materials, and lowering the temperature of the CO2. The heat-exchanged CO2 can be removed to the outside through the exhaust CO2 pipe 72d of the CO2 heat exchanger 70. The CO2 removed to the outside is immobilized, for example, by storing it underground or under the seabed. The preheated cement raw materials are separated in the solid-gas separator 71a and transported by the transport path E to the raw material inlet of the indirectly heated calcination furnace 20.

[0048] In the cooling process, the combustion exhaust gas discharged from the indirectly heated calcination furnace 20 is cooled to 450°C or below. The high-temperature mixed gas, including the combustion exhaust gas discharged from the indirectly heated calcination furnace 20, is sent to the solid-gas separator 31 via the combustion exhaust gas pipe 30, where it is mixed with the kiln exhaust gas to produce a mixed exhaust gas. The temperature of the mixed exhaust gas in the solid-gas separator 31 is, for example, between 750°C and 850°C. The reaction between calcium oxide and CO2 to produce calcium carbonate is an exothermic reaction. Therefore, if the mixed exhaust gas is brought into contact with the calcined cement raw material sent from the second transport path A2 at the above temperature, and the mixed exhaust gas reacts with the calcium oxide in the calcined cement raw material, the temperature of the high-temperature mixed gas may rise further, suppressing the reaction between calcium oxide and CO2 and making it difficult to produce calcium carbonate. For this reason, in this embodiment, the temperature of the mixed exhaust gas is set to 450°C or below, preferably 300°C or below, in the cooling process.

[0049] The cooling process is performed in the exhaust gas heat exchanger 40. In this embodiment, the cooling process is performed as follows: The mixed exhaust gas introduced into the piping 42a of the exhaust gas heat exchanger 40 flows upward. Cement raw materials are supplied to this mixed exhaust gas in piping 42c. The cement raw materials supplied to piping 42c flow into the solid-gas separator 41c, accompanied by the mixed exhaust gas flowing through piping 42c. In the solid-gas separator 41c, the cement raw materials and the mixed exhaust gas are separated, and the separated cement raw materials are sent to piping 42b. The cement raw materials sent to piping 42b flow into the solid-gas separator 41b, accompanied by the mixed exhaust gas flowing through piping 42b. In the solid-gas separator 41b, the cement raw materials and the mixed exhaust gas are separated, and the separated cement raw materials are sent to piping 42a. The cement raw materials sent to piping 42a flow into the solid-gas separator 41a, accompanied by the mixed exhaust gas flowing through piping 42a. In the solid-gas separator 41a, the cement raw material and the mixed exhaust gas are separated, and the separated cement raw material is sent to the kiln exhaust gas pipe 14. The cement raw material sent to the kiln exhaust gas pipe 14 flows into the solid-gas separator 31 along with the kiln exhaust gas flowing through the kiln exhaust gas pipe 14. In the solid-gas separator 31, the cement raw material and the mixed exhaust gas are separated, and the separated cement raw material is sent to the raw material inlet of the indirectly heated calcination furnace 20 via the transport path B. When the cement raw material and the mixed exhaust gas come into contact, the heat from the mixed exhaust gas is transferred to the cement raw material, preheating the cement raw material and lowering the temperature of the mixed exhaust gas.

[0050] In the calcium carbonate production process, calcium carbonate is produced by contacting combustion exhaust gas (mixed exhaust gas) cooled to 450°C or below with calcium oxide, thereby reacting CO2 in the combustion exhaust gas with the calcium oxide. The calcium carbonate production process is carried out in the reaction tube 51 of the reaction apparatus 50. In this embodiment, the calcium carbonate production process is carried out as follows: The mixed exhaust gas introduced into the reaction tube 51 of the reaction apparatus 50 is brought into contact with the calcined cement raw material introduced into the reaction tube 51, causing the CO2 in the mixed exhaust gas to react with the calcium oxide in the calcined cement raw material. The temperature of the reaction products (calcium carbonate and reaction product gas) produced by the reaction of calcium oxide and CO2 is preferably 750°C or below. When the temperature of the reaction products is within this range, the reaction between calcium oxide and CO2 occurs more easily, and calcium carbonate is produced more easily. In order to lower the temperature of the reaction products, it is preferable to cool the calcined cement raw material introduced into the reaction tube 51 to 300°C or below in the cooler 56. Alternatively, a cooling unit may be provided in either or both of the reaction tube 51 and the solid-gas separator 52 to cool the inside of either or both of the reaction tube 51 and the solid-gas separator 52 to 750°C or below. A boiler that generates steam by the endothermic effect of water can be used as the cooling unit.

[0051] In the calcium carbonate supply process, the calcium carbonate produced in the calcium carbonate generation process is supplied to the raw material inlet of the indirectly heated calcination furnace 20. The calcium carbonate supply process is carried out in the solid-gas separator 52 and transport path C of the reaction apparatus 50. In this embodiment, the calcium carbonate supply process is carried out as follows: The reaction products (calcium carbonate and reaction product gas) produced in the reaction tube 51 of the reaction apparatus 50 are sent to the solid-gas separator 52. In the solid-gas separator 52, the reaction products are separated into calcium carbonate and reaction product gas. The calcium carbonate is taken out from the calcium carbonate outlet of the solid-gas separator 52 and sent to the raw material inlet of the indirectly heated calcination furnace 20 via the transport path C. In the indirectly heated calcination furnace 20, the calcium carbonate is heated and calcined to produce cement raw material calcined product and CO2. The CO2 produced from calcium carbonate contains a large amount of CO2 derived from the fuel. Therefore, CO2 derived from the fuel can be recovered efficiently.

[0052] The reaction product gas extracted from the reaction product gas outlet of the solid-gas separator 52 is sent to the reaction product gas heat exchanger 60. In the reaction product gas heat exchanger 60, the reaction product gas comes into contact with the cement raw materials, transferring heat from the reaction product gas to the cement raw materials, preheating the cement raw materials, and lowering the temperature of the reaction product gas. Since the heat-exchanged reaction product gas does not contain much CO2, it can be released to the outside through the exhaust gas pipe 62d of the reaction product gas heat exchanger 60. Alternatively, the heat from the heat-exchanged reaction product gas may be recovered in a waste heat boiler or used to dry the cement raw materials.

[0053] Cement production takes place in cement production kiln 10. In this embodiment, the calcined cement raw material separated in the solid-gas separator 22 is transported to the cement manufacturing kiln 10 via the first transport path A1 after passing through the calcium oxide amount control device 55. The calcined cement raw material transported from the first transport path A1 is fired in the furnace body 11 of the cement manufacturing kiln 10 by the main burner 12, thereby generating cement clinker. The generated cement clinker is sent to the clinker cooler 13. In the clinker cooler 13, the cement clinker is cooled. The cooled cement clinker is crushed and classified and used as cement.

[0054] According to the CO2 recovery system 101 of the cement manufacturing equipment of this embodiment, configured as described above, the cement raw materials are indirectly calcined in the indirectly heated calcination furnace 20 using combustion gas to generate calcined cement raw materials and CO2, thereby generating a high concentration of CO2 within the indirectly heated calcination furnace 20. Furthermore, in the reaction unit 50, CO2 in the combustion exhaust gas is reacted with calcium oxide to produce calcium carbonate, and the produced calcium carbonate is supplied to the indirectly heated calcination furnace 20 via the transport path C, thereby recovering CO2 from the combustion exhaust gas. Moreover, after reducing the temperature of the combustion exhaust gas using an exhaust gas heat exchanger, the reaction between calcium oxide and CO2 in the reaction unit is accelerated. As a result, the efficiency of CO2 recovery from the combustion exhaust gas is improved. Therefore, according to the CO2 recovery system 101 of the cement manufacturing equipment, both CO2 originating from raw materials and CO2 originating from fuel can be efficiently recovered. Furthermore, by utilizing the heat generated by the reaction between calcium oxide and CO2 in the combustion exhaust gas for preheating cement raw materials, the amount of heat (combustion gas used) required for indirect heating of the cement raw materials can be reduced. Therefore, the amount of CO2 generated from the fuel can be reduced.

[0055] Furthermore, in the CO2 recovery system 101 of the cement manufacturing equipment of this embodiment, if there is a kiln exhaust gas pipe 14 that transports the exhaust gas from the cement manufacturing kiln 10 to the intake port (piping 42a) of the exhaust gas heat exchanger 40, then CO2 in the exhaust gas from the cement manufacturing kiln 10 can be recovered along with the CO2 in the combustion exhaust gas. In addition, by using the reaction heat generated by reacting the CO2 in the exhaust gas of the cement manufacturing kiln 10 with calcium oxide, the amount of combustion gas used in the cement manufacturing kiln 10 can be further reduced. Therefore, the amount of CO2 generated from fuel can be reduced.

[0056] Furthermore, in the CO2 recovery system 101 of the cement manufacturing equipment of this embodiment, if the cement raw material calcined contains calcium oxide, and there is a first transport path A1 that transports the cement raw material calcined, which has been removed from the calcined material outlet of the indirect heating type calcination furnace 20, to the cement manufacturing kiln, and a second transport path A2 that transports it to the calcium oxide inlet of the reaction device, then CO2 in the combustion exhaust gas can be recovered using the cement raw material calcined. In addition, it becomes easier to adjust the amount of calcium oxide that comes into contact with the CO2 in the combustion exhaust gas.

[0057] Furthermore, in the CO2 recovery system 101 of the cement manufacturing equipment of this embodiment, if a cooler 56 is placed in the second transport path A2, the temperature of the calcium oxide that comes into contact with the combustion exhaust gas can be lowered. Therefore, even if reaction heat is generated by the reaction of CO2 in the combustion exhaust gas with calcium oxide, the temperature of the generated calcium carbonate can be maintained at a predetermined temperature. As a result, the temperature of the combustion exhaust gas is less likely to rise, and CO2 in the combustion exhaust gas can be recovered with higher efficiency.

[0058] Furthermore, in the CO2 recovery system 101 of the cement manufacturing equipment of this embodiment, if there is a calcium oxide amount control device 55 that controls the amount of calcined cement raw material transported to the cement manufacturing kiln 10 and the amount of calcined cement raw material transported to the calcium oxide inlet of the reaction device 50, the amount of calcined cement raw material (calcium oxide) transported to the reaction device 50 can be adjusted. This allows the amount of calcium oxide necessary to recover CO2 from the combustion exhaust gas to be transported to the reaction device 50, thereby enabling the recovery of fuel-derived CO2 with higher efficiency.

[0059] Furthermore, in the CO2 recovery system 101 of the cement manufacturing equipment of this embodiment, when the calcium oxide amount control device 55 adjusts the amount of calcium oxide transported to the calcium oxide inlet of the reactor 50 based on either or both of the CO2 concentration of the gas introduced from the gas inlet (reaction tube 51) of the reactor 50 and the CO2 concentration of the gas exhausted from the gas outlet (solid-gas separator 52) of the reactor 50, it can reliably supply the reactor 50 with the amount of calcium oxide necessary to recover CO2 from the combustion exhaust gas. As a result, CO2 from the combustion gas can be recovered with even higher efficiency.

[0060] Furthermore, in the CO2 recovery system 101 of the cement manufacturing equipment of this embodiment, if the calcium oxide amount control device 55 adjusts the amount of calcium oxide transported to the calcium oxide inlet of the reactor 50 based on either or both of the temperature of the gas exhausted from the gas outlet of the reactor 50, the temperature of the calcium carbonate taken out from the calcium carbonate outlet, then it can reliably supply the reactor 50 with the amount of calcium oxide necessary to recover CO2 from the combustion exhaust gas. As a result, CO2 from the combustion gas can be recovered with even higher efficiency.

[0061] Furthermore, in the CO2 recovery system 101 of the cement manufacturing facility of this embodiment, if the calcium oxide amount control device 55 adjusts the amount of calcium oxide transported to the calcium oxide inlet of the reactor 50 based on the temperature of the gas introduced from the exhaust gas inlet of the reactor 50, the temperature of the calcium oxide introduced to the calcium oxide inlet of the reactor 50, or both, then it can more reliably supply the reactor 50 with the amount of calcium oxide necessary to recover CO2 from the combustion exhaust gas. As a result, CO2 from the combustion gas can be recovered with even higher efficiency.

[0062] Furthermore, in the CO2 recovery system 101 of the cement manufacturing equipment of this embodiment, when the calcium oxide amount control device 55 adjusts the amount of calcium oxide transported to the calcium oxide inlet of the reactor 50 based on either or both of the CO2 concentration of the gas introduced from the gas inlet (reaction tube 51) of the reactor 50 and the CO2 concentration of the gas exhausted from the gas outlet (solid-gas separator 52) of the reactor 50, it can reliably supply the reactor 50 with the amount of calcium oxide necessary to recover CO2 from the combustion exhaust gas. As a result, CO2 from the combustion gas can be recovered with even higher efficiency.

[0063] Furthermore, in the CO2 recovery system 101 of the cement manufacturing equipment of this embodiment, if the exhaust gas heat exchanger 40 is a preheater that includes a cement raw material inlet and solid-gas separation devices 41a, 41b, and 41c that separate the cement raw material supplied from the cement raw material inlet from the combustion exhaust gas, and has a cement raw material quantity control device that controls the amount of cement raw material supplied from the cement raw material inlet of the preheater, then the cement raw material is preheated with the heat of the combustion exhaust gas, so the amount of heat used when indirectly heating the cement raw material, i.e., the amount of combustion gas used, can be reduced. Therefore, the amount of CO2 generated from fuel can be reduced.

[0064] Furthermore, in the CO2 recovery system 101 of the cement manufacturing equipment of this embodiment, if the reactor 50 has a cooling unit, the reaction between CO2 and calcium oxide in the reactor 50 is promoted by lowering the temperature inside the reactor 50 using the cooling unit. Therefore, the recovery efficiency of CO2 in the combustion exhaust is improved.

[0065] Furthermore, in the CO2 recovery system 101 of the cement manufacturing equipment of this embodiment, if the cooling unit is a boiler that generates steam by the absorption of heat from water, the temperature inside the reaction apparatus 50 can be efficiently reduced.

[0066] Furthermore, in the CO2 recovery system 101 of the cement manufacturing equipment of this embodiment, if there is a pressure reducing device for reducing the internal pressure of the indirectly heated calcination furnace 20, the thermal decomposition temperature of calcium carbonate inside the indirectly heated calcination furnace 20 can be lowered by reducing the internal pressure of the indirectly heated calcination furnace 20. This reduces the amount of heat used when indirectly heating the cement raw materials, i.e., the amount of combustion gas used. Therefore, the amount of CO2 generated from fuel can be reduced.

[0067] Furthermore, in the CO2 recovery system 101 of the cement manufacturing equipment of this embodiment, if there is a pressurizing device that increases the internal pressure of the reactor 50, the thermal decomposition temperature of calcium carbonate can be increased by increasing the internal pressure of the reactor 50. This promotes the reaction between CO2 in the combustion exhaust gas and calcium oxide, and allows for the recovery of CO2 in the combustion exhaust gas with even higher efficiency.

[0068] Furthermore, according to the CO2 recovery method for the cement manufacturing equipment of this embodiment, in the CO2 recovery process, the cement raw materials are indirectly calcined using combustion gas to generate calcined cement raw materials and CO2, thereby generating a high concentration of CO2 in the indirect heating calcination furnace 20. In addition, in the calcium carbonate production process, CO2 in the combustion exhaust gas is reacted with calcium oxide to produce calcium carbonate, and in the calcium carbonate supply process, the produced calcium carbonate is supplied to the indirect heating calcination furnace via the transport path C, thereby recovering CO2 from the combustion exhaust gas. Moreover, in the cooling process, the temperature of the combustion exhaust gas is reduced to 450°C or below using an exhaust gas heat exchanger, and then in the calcium carbonate production process, the CO2 in the combustion exhaust gas is reacted with calcium oxide, thus promoting the reaction between CO2 and calcium oxide. Therefore, the efficiency of CO2 recovery from the combustion exhaust gas is improved. Consequently, according to the CO2 recovery method for the cement manufacturing equipment of this embodiment, both CO2 originating from raw materials and CO2 originating from fuel can be efficiently recovered. Furthermore, the amount of combustion gas used can be reduced by utilizing the heat generated by the reaction between calcium oxide and CO2 in the combustion exhaust gas for preheating cement raw materials, etc.

[0069] Furthermore, in the CO2 recovery method for the cement manufacturing equipment of this embodiment, before introducing the combustion gas into the exhaust gas heat exchanger 40, a mixing step is included in which the combustion exhaust gas and the exhaust gas generated in the cement manufacturing kiln 10 are mixed to produce a mixed exhaust gas. In the cooling step, if the mixed exhaust gas is cooled to 450°C or below, CO2 in the combustion exhaust gas and CO2 in the exhaust gas of the cement manufacturing kiln can be recovered. In addition, by using the reaction heat generated by reacting CO2 in the exhaust gas of the cement manufacturing kiln 10 with calcium oxide, the amount of combustion gas used when indirectly heating the cement raw materials and the amount of combustion gas used in the cement manufacturing kiln 10 can be reduced. Thus, the amount of CO2 generated from fuel can be reduced.

[0070] (Second Embodiment) Figure 1 is a schematic diagram showing a CO2 recovery system for a cement manufacturing facility according to a second embodiment of the present invention. In Figure 2, components identical to those in the CO2 recovery system 101 of the cement manufacturing facility according to the first embodiment shown in Figure 1 are denoted by the same reference numerals, and their descriptions are simplified.

[0071] As shown in Figure 2, in the second embodiment of the cement manufacturing facility, the CO2 recovery system 102 has a non-source CO2-containing gas transport piping 80 connected to the reaction pipe 51 of the reaction apparatus 50. The non-source CO2-containing gas is CO2-containing gas generated in equipment other than the cement manufacturing kiln 10 and the indirect heating type calcination furnace 20. The temperature of the non-source CO2-containing gas is 450°C or lower, preferably 300°C or lower.

[0072] In the CO2 recovery system 102 of the cement manufacturing equipment of this embodiment, a CO2-containing gas is present in the reaction tube 51, which includes a mixed exhaust gas sent from the exhaust gas heat exchanger 40 and a CO2-containing gas from a different emission source. By bringing the generated CO2-containing gas into contact with the calcined cement raw material, a reaction product gas is generated from which calcium carbonate and CO2 have been removed.

[0073] The CO2 recovery system 102 of the cement manufacturing facility in this embodiment is the same as the CO2 recovery system 101 of the cement manufacturing facility in Figure 1, except that a gas transport pipe 80 containing CO2 from an external emission source is connected to the reaction pipe 51, and therefore has the same effects as the CO2 recovery system 101 of the cement manufacturing facility. Furthermore, since the CO2 recovery system 102 of the cement manufacturing facility in this embodiment reacts CO2 in the gas containing CO2 from an external emission source with calcium oxide, CO2 in the gas containing CO2 from an external emission source can be recovered simply and efficiently, and the amount of CO2 released into the atmosphere can be reduced.

[0074] Although embodiments of the present invention have been described above, the present invention is not limited thereto and can be modified as appropriate without departing from the technical spirit of the invention. For example, in this embodiment, the indirect heating type calcination furnace 20 is configured to include a combustion gas pipe 23 through which combustion gas flows. However, the indirect heating type calcination furnace 20 is not particularly limited in its configuration as long as it is configured to adjust the furnace temperature without direct contact between the cement raw material and the combustion gas. The indirect heating type calcination furnace 20 may also adjust the furnace temperature using a solid heat transfer medium. As an example of the indirect heating type calcination furnace 20, one can be used that has a heat transfer medium heating section and a cement raw material calcination section, and adjusts the furnace temperature by supplying the heat transfer medium heated using combustion gas in the heat transfer medium heating section to the cement raw material calcination section. In this indirect heating type calcination furnace, the combustion gas discharged from the heat transfer medium heating section becomes the combustion exhaust gas. Alternatively, a portion of the cement raw material calcined by a solid-gas separation device 22 connected to the indirect heating type calcination furnace 20 may be returned to the indirect heating type calcination furnace 20 via the heat transfer medium heating section as a heat transfer medium. Furthermore, a portion of the clinker obtained in the cement manufacturing kiln 10 may be supplied to the indirectly heated calcination furnace 20 as a heat transfer medium. [Explanation of Symbols]

[0075] 10. Kiln for cement production 11 Furnace body 12 Main Burner 13. Clinka Cooler 14 Kiln exhaust pipe 20 Indirect heating type calcination furnace 21. Tempered material removal pipe 22. Solid-gas separation device 23 Combustion gas pipe 30 Combustion exhaust gas pipe 31. Solid-gas separation device 40 Exhaust gas heat exchanger 41a, 41b, 41c Solid-gas separation equipment 42a, 42b, 42c Piping 50 Reactor 51 Reaction tube 52 Solid-gas separation apparatus 53 Blower 55 Calcium Oxide Amount Control Device 56 Cooler 60. Reaction product gas heat exchanger 61a, 61b, 61c Solid-gas separator 62a, 62b, 62c Piping 62d Exhaust pipe 63 Blower 70 CO2 heat exchanger 71a, 71b, 71c Solid-gas separation equipment 72a, 72b, 72c Piping 72d CO2 exhaust pipe 72d 73 Blower 80. Gas transport piping containing CO2 from different emission sources 101, 102 CO2 capture system for cement manufacturing facilities

Claims

1. A kiln for cement production, and a raw material inlet, a calcined material outlet, and CO ２ It is equipped with an outlet and indirectly calcines the cement raw materials introduced from the raw material inlet using combustion gas to form a calcined cement raw material and CO2 ２ CO2 production facility having an indirect heating type calcination furnace that generates CO2 ２ It is a collection system, A combustion exhaust gas pipe through which exhaust gas containing combustion exhaust gas discharged from the aforementioned indirectly heated calcination furnace flows, An exhaust gas heat exchanger having an intake port and an exhaust port connected to the aforementioned combustion exhaust gas pipe, The exhaust gas heat exchanger has an exhaust gas inlet connected to the exhaust port, a calcium oxide inlet, a calcium carbonate outlet, and a gas outlet, and by bringing the exhaust gas introduced from the exhaust gas inlet into contact with the calcium oxide introduced from the calcium oxide inlet, the CO in the exhaust gas ２ A reaction apparatus for reacting the aforementioned calcium oxide with calcium carbonate, A cement manufacturing facility having a conveying device that transports the calcium carbonate extracted from the calcium carbonate outlet of the reaction device to the raw material inlet of the indirectly heated calcination furnace, CO ２ Collection system.

2. The cement manufacturing equipment according to claim 1, comprising piping for transporting the exhaust gas generated in the cement manufacturing kiln to the intake port of the exhaust gas heat exchanger, wherein CO ２ Collection system.

3. The cement manufacturing equipment according to claim 1 or 2, wherein the cement raw material calcined material contains calcium oxide, and the cement raw material calcined material removed from the calcined material outlet of the indirect heating type calcination furnace is transported to the cement manufacturing kiln, and the CO2 is transported to the calcium oxide inlet of the reaction apparatus. ２ Collection system.

4. The CO2 manufacturing facility according to claim 3, wherein a cooler is arranged in the second transport path. ２ Collection system.

5. The cement production facility CO recovery system according to claim 3, comprising a calcium oxide amount control device that controls the amount of the semi-calcined cement raw material conveyed to the kiln for cement production and the amount of the semi-calcined cement raw material conveyed to the calcium oxide inlet of the reactor. ２ recovery system.

6. The calcium oxide quantity control device controls the CO2 gas introduced from the exhaust gas inlet of the reactor. ２ The CO concentration and the CO gas exhausted from the gas outlet of the reaction apparatus. ２ CO2 manufacturing equipment according to claim 5, which adjusts the amount of calcium oxide delivered to the calcium oxide inlet of the reaction apparatus based on one or both of the concentrations. ２ Collection system.

7. The calcium oxide quantity control device adjusts the amount of calcium oxide transported to the calcium oxide inlet of the reactor based on either or both the temperature of the gas exhausted from the gas outlet of the reactor, the temperature of the calcium carbonate taken out from the calcium carbonate outlet, and / or the CO2 inlet of the reactor according to claim 5. ２ Collection system.

8. The calcium oxide quantity control device further adjusts the amount of calcium oxide to be transported to the calcium oxide inlet of the reactor based on the temperature of the gas introduced from the exhaust gas inlet of the reactor, the temperature of the calcium oxide introduced into the calcium oxide inlet of the reactor, or both, in the CO2 manufacturing facility according to claim 7. ２ Collection system.

9. The CO2 manufacturing facility according to claim 1 or 2, wherein the exhaust gas heat exchanger is a preheater including a cement raw material inlet and a solid-gas separation device for separating the cement raw material supplied from the cement raw material inlet from the combustion exhaust gas, and the CO2 manufacturing facility is further comprising a cement raw material quantity control device for controlling the amount of cement raw material supplied from the cement raw material inlet of the preheater. ２ Collection system.

10. The CO2 manufacturing apparatus according to claim 1 or 2, having a cooling unit within the reaction apparatus ２ Collection system.

11. The CO2 manufacturing facility according to claim 10, wherein the cooling unit is a boiler that generates steam by the absorption of heat from water. ２ Collection system.

12. The cement manufacturing facility according to claim 1 or 2, which has a pressure reducing device for reducing the internal pressure of the indirectly heated calcination furnace CO ２ Collection system.

13. The CO2 manufacturing facility according to claim 1 or 2, which has a pressurizing device for increasing the internal pressure of the reaction apparatus ２ Collection system.

14. CO generated in equipment other than the cement manufacturing kiln and the indirectly heated calcination furnace ２ CO2 manufacturing equipment according to claim 1 or 2, having piping for transporting the contained gas to the intake port of the exhaust gas heat exchanger or the exhaust gas inlet of the reaction device ２ Collection system.

15. A kiln for cement production, and a raw material inlet, a calcined material outlet, and CO ２ CO2 manufacturing equipment having an indirectly heated calcination furnace equipped with an outlet ２ A collection method, The cement raw materials introduced from the raw material inlet of the aforementioned indirect heating type calcination furnace are indirectly heated and calcined using combustion gas to form a calcined cement raw material and CO2. ２ To generate the CO ２ CO2 recovery ２ The recovery process, A cooling step is performed in which the combustion exhaust gas discharged from the indirect heating type calcination furnace is introduced into an exhaust gas heat exchanger and cooled to 450°C or below. By bringing the combustion exhaust gas, cooled to below 450°C, into contact with calcium oxide, the CO in the combustion exhaust gas is reduced. ２ A calcium carbonate production step in which calcium oxide is reacted with the calcium carbonate to produce calcium carbonate, A cement manufacturing facility comprising a calcium carbonate supply step of supplying the calcium carbonate to the raw material inlet of the indirectly heated calcination furnace, and CO ２ Collection method.

16. The CO2 manufacturing facility according to claim 15, comprising a mixing step of mixing the combustion exhaust gas with the exhaust gas generated in the cement manufacturing kiln to produce a mixed exhaust gas before introducing the combustion gas into the exhaust gas heat exchanger, and a cooling step of cooling the mixed exhaust gas to 450°C or below. ２ Collection method.

Images