JP7052360B2 - Methane production equipment, methane production method - Google Patents

Description

The present invention relates to a methane production apparatus.

A technique for producing methane (CH ₄ ) from carbon dioxide (CO ₂ ) and hydrogen (H ₂ ) is known. For example, Non-Patent Document 1 describes a first step of occluding carbon dioxide from a raw material gas in a single reactor containing a catalyst having carbon dioxide occluding and reducing performance, and reducing the occluded carbon dioxide. It is described that both the second step and the second step of producing methane are carried out. For example, Patent Document 1 includes a plurality of reactors (reactors), and in a certain reactor, a first step of simultaneously supplying carbon dioxide and hydrogen to convert carbon dioxide into carbon (C) is carried out. It is described that in other reactors, the supply of carbon dioxide is stopped and the supply of hydrogen is continued to carry out the second step of converting carbon into methane, and the roles of these reactors are switched at regular intervals. There is.

Zheng, Qinghe, Robert Farrauto, and Anh Chau Nguyen, "Adsorption and Methanation of Flue Gas CO2 with Dual Functional Catalytic Materials: A Parametric Study.", Industrial & Engineering Chemistry Research, American Chemical Society, June 2016, 55 (24), p. 6768-6767

Japanese Unexamined Patent Publication No. 5-193920

In Non-Patent Document 1, the raw material gas containing carbon dioxide is supplied into the reactor in the first step, and the reduced gas containing hydrogen is supplied into the reactor in the second step. That is, in Non-Patent Document 1, since it is essential to switch the gas to the reactor between the first and second steps, it becomes necessary to provide a large number of valves in the reactor, and there is a problem that the apparatus configuration becomes complicated. rice field. Specifically, at least a valve for supplying raw material gas and a valve for supplying reducing gas are required upstream of the reactor, and at least a valve for discharging oxygen and a valve for discharging methane are required downstream of the reactor. Is. Further, when a purging step for discharging the residual gas in the reactor is provided between the first and second steps, a further valve for supplying and discharging the nitrogen (N ₂ ) gas for purging is required.

Further, in Non-Patent Document 1, the first step of occluding carbon dioxide and the second step of producing methane are sequentially carried out while switching the type of gas supplied to the reactor. Therefore, in Non-Patent Document 1, there is a problem that the amount of methane produced by occlusion and reduction of carbon dioxide (methane production amount) varies with time and cannot be stabilized.

In Patent Document 1, since the catalyst moves between a plurality of reactors, it is not always necessary to switch the gas to the reactor, and it is not always necessary to provide a large number of valves. However, Patent Document 1 does not describe the production of methane using a catalyst having carbon dioxide occlusion and reduction performance. Further, in Patent Document 1, since the gas containing carbon dioxide serves as a carrier for catalyst transport between the reactors, the amount of carbon recovered in the reactor that executes the first step of converting carbon dioxide into carbon becomes a matter of course. .. Along with this, the amount of methane produced by the reaction between carbon and hydrogen (methane production amount) also becomes the same as the carbon recovery amount, and there is a problem that the methane production amount cannot be stabilized.

The present invention has been made to solve the above-mentioned problems, and in the production of methane using a catalyst having carbon dioxide occlusion and reduction performance, the device configuration is simplified and the amount of methane produced is stabilized. The purpose is to plan.

The present invention has been made to solve at least a part of the above-mentioned problems, and can be realized as the following forms.
One embodiment of the present invention is a methane production apparatus for producing methane from carbon dioxide and hydrogen, which comprises a first reactor and a second reactor containing a slurry containing a catalyst having carbon dioxide storage and reduction performance. A raw material gas supply unit that supplies a raw material gas containing carbon dioxide to the first reactor, a reducing gas supply unit that supplies a reducing gas containing hydrogen to the second reactor, and the first reactor. A first flow path forming portion for forming a first flow path for transferring the slurry containing the catalyst containing carbon dioxide from the reactor to the second reactor, and the second reactor to the first flow path. A second flow path forming portion for forming a second flow path for transferring the slurry containing the catalyst after the stored carbon dioxide has been used in the reaction with hydrogen, and the first reactor. A pump for circulating the slurry between one reactor and the second reactor is provided.
In such a form, carbon dioxide contained in the raw material gas supplied from the raw material gas supply unit is occluded in the catalyst in the first reactor. In the second reactor, hydrogen contained in the reducing gas supplied from the reducing gas supply unit reacts with carbon dioxide occluded in the catalyst to generate methane. In this configuration, the catalyst contained in the first and second reactors is made into a flowable slurry, and the slurry is formed between the first reactor and the second reactor by the first and second flow path forming portions and the pump. To circulate. Therefore, unlike the conventional case, it is not necessary to carry out both the occlusion step of carbon dioxide from the raw material gas and the methanation step of carbon dioxide using the reducing gas in a single reactor. , 2 Reactors can be supplied with the same gas at all times. As a result, according to this configuration, since a mechanism (valve or the like) for switching the gas to the reactor and switching the gas is not required, the apparatus configuration of the methane production apparatus can be simplified. Further, according to this configuration, since it is not necessary to switch the gas to the reactor, the flow rate of the raw material gas from the raw material gas supply unit to the first reactor and the reduction gas from the reducing gas supply unit to the second reactor The amount of methane produced can be stabilized by stabilizing the flow rate of. As described above, according to this configuration, in the production of methane using a catalyst having carbon dioxide occlusion and reduction performance, it is possible to simplify the apparatus configuration and stabilize the amount of methane produced. Further, according to this configuration, the residence time of the catalyst in the first and second reactors can be controlled by changing the flow rate of the pump. Therefore, for example, in order to achieve the target carbon dioxide recovery rate even when the flow rate or composition (carbon dioxide content) of the raw material gas supplied from the raw material gas supply unit to the first reactor changes. The required residence time can be easily secured.
In addition, the present invention can also be realized in the following forms.

(1) According to one embodiment of the present invention, a methane production apparatus for producing methane from carbon dioxide and hydrogen is provided. This methane production apparatus supplies a first reactor and a second reactor accommodating a slurry containing a catalyst having carbon dioxide storage and reduction performance, and a raw material gas containing carbon dioxide to the first reactor. The raw material gas supply unit, the reduction gas supply unit that supplies the reduction gas containing hydrogen to the second reactor, and the slurry for transferring the slurry from the first reactor to the second reactor. A first flow path forming portion that forms a first flow path, a second flow path forming portion that forms a second flow path for transferring the slurry from the second reactor to the first reactor, and a second flow path forming portion. A pump for circulating the slurry between the first reactor and the second reactor is provided.

According to this configuration, in the first reactor, carbon dioxide contained in the raw material gas supplied from the raw material gas supply unit is occluded in the catalyst. In the second reactor, hydrogen contained in the reducing gas supplied from the reducing gas supply unit reacts with carbon dioxide occluded in the catalyst to generate methane. In this configuration, the catalyst contained in the first and second reactors is made into a flowable slurry, and the slurry is formed between the first reactor and the second reactor by the first and second flow path forming portions and the pump. To circulate. Therefore, unlike the conventional case, it is not necessary to carry out both the occlusion step of carbon dioxide from the raw material gas and the methanation step of carbon dioxide using the reducing gas in a single reactor. , 2 Reactors can be supplied with the same gas at all times. As a result, according to this configuration, since a mechanism (valve or the like) for switching the gas to the reactor and switching the gas is not required, the apparatus configuration of the methane production apparatus can be simplified. Further, according to this configuration, since it is not necessary to switch the gas to the reactor, the flow rate of the raw material gas from the raw material gas supply unit to the first reactor and the reduction gas from the reducing gas supply unit to the second reactor The amount of methane produced can be stabilized by stabilizing the flow rate of. As described above, according to this configuration, in the production of methane using a catalyst having carbon dioxide occlusion and reduction performance, it is possible to simplify the apparatus configuration and stabilize the amount of methane produced. Further, according to this configuration, the residence time of the catalyst in the first and second reactors can be controlled by changing the flow rate of the pump. Therefore, for example, in order to achieve the target carbon dioxide recovery rate even when the flow rate or composition (carbon dioxide content) of the raw material gas supplied from the raw material gas supply unit to the first reactor changes. The required residence time can be easily secured.

(2) In the methane production apparatus of the above embodiment, further, a first concentration acquisition unit for acquiring the carbon dioxide concentration in the raw material gas, a first flow rate acquisition unit for acquiring the flow rate of the raw material gas, and the first reaction. A second concentration acquisition unit that acquires the concentration of carbon dioxide in the exhaust gas discharged from the reactor, a second flow rate acquisition unit that acquires the flow rate of the exhaust gas discharged from the first reactor, a control unit, and the control unit. May be provided. The control unit includes the pump and the pump according to at least a part of the acquired values by the first concentration acquisition unit, the first flow rate acquisition unit, the second concentration acquisition unit, and the second flow rate acquisition unit. At least one of the reduced gas from the reduced gas supply unit may be controlled. According to this configuration, the control unit depends on at least a part of the carbon dioxide concentration in the raw material gas, the flow rate of the raw material gas, the carbon dioxide concentration in the exhaust gas, and the flow rate of the exhaust gas, for example. , The flow rate of the pump that circulates the slurry containing the catalyst, the presence or absence of operation, the flow rate and concentration of the reducing gas supplied from the reducing gas supply unit, the composition, and the like can be controlled. Therefore, according to this configuration, it is possible to further stabilize the amount of methane produced in the production of methane using a catalyst having carbon dioxide occlusion and reduction performance.

(3) In the methane production apparatus of the above embodiment, the control unit has the carbon dioxide concentration in the raw material gas acquired by the first concentration acquisition unit and the raw material gas acquired by the first flow rate acquisition unit. The flow rate of the pump may be changed in inverse proportion to both the flow rate and the flow rate. According to this configuration, the control unit changes the flow rate of the pump in inverse proportion to both the concentration of carbon dioxide in the raw material gas and the flow rate of the raw material gas, so that carbon dioxide is sufficiently occluded in the catalyst in the first reactor. The catalyst can be allowed to stay in the first reactor until the time is reached. As a result, the amount of carbon dioxide recovered in the first reactor can be improved.

(4) In the methane production apparatus of the above embodiment, the control unit has the carbon dioxide concentration in the raw material gas acquired by the first concentration acquisition unit and the raw material gas acquired by the first flow rate acquisition unit. From the amount of carbon dioxide in the raw material gas obtained from the flow rate, the carbon dioxide concentration in the exhaust gas acquired by the second concentration acquisition unit and the flow rate of the exhaust gas acquired by the second flow rate acquisition unit. By reducing the amount of carbon dioxide in the exhaust gas obtained from the above, the amount of carbon dioxide recovered in the first reactor was obtained, and it was proportional to both the obtained amount of carbon dioxide recovered and the flow rate of the pump. Therefore, the supply amount of the reduced gas from the reduced gas supply unit may be changed. According to this configuration, the control unit changes the supply amount of the reducing gas in proportion to both the carbon dioxide recovery amount in the first reactor and the flow rate of the pump, so that the carbon dioxide in the second reactor is changed each time. It is possible to supply just the right amount of hydrogen for the reduction of carbon dioxide. As a result, the amount of methane produced in the second reactor can be improved, and the amount of reduced gas consumed can be suppressed.

(5) In the methane production apparatus of the above embodiment, a third reactor provided on the first flow path and accommodating the slurry and a fourth reaction provided on the second flow path and accommodating the slurry are further provided. A vessel may be provided, and at least one of the reactors may be provided, and a purge gas supply unit for supplying the purge gas to at least one of the third reactor and the fourth reactor may be provided. According to this configuration, the gas (oxygen, nitrogen, etc.) remaining in the catalyst contained in the slurry transferred on the first flow path can be discharged by using the third reactor. Further, the fourth reactor can be used to discharge the gas (hydrogen, etc.) remaining in the catalyst contained in the slurry transferred on the second flow path.

(6) In the methane production apparatus of the above embodiment, further, among the first gas-liquid separator provided on the first flow path and the second gas-liquid separator provided on the second flow path. It may have at least one of them. According to this configuration, the gas (oxygen, nitrogen, etc.) remaining in the catalyst contained in the slurry transferred on the first flow path can be discharged by using the first gas-liquid separator. Further, the gas (hydrogen, etc.) remaining in the catalyst contained in the slurry transferred on the second flow path can be discharged by using the second gas-liquid separator.

(7) In the methane production apparatus of the above embodiment, the catalyst is at least one of an alkali metal that forms a carbonate and occludes carbon dioxide, an alkaline earth metal, and a metal having a methaneation catalyst performance. May include. According to this configuration, various catalysts can be used as catalysts having carbon dioxide occlusion and reduction performance.

(8) According to one embodiment of the present invention, there is provided a methane production method for producing methane from carbon dioxide and hydrogen. This methane production method includes a step of supplying a raw material gas containing carbon dioxide to a first reactor containing a slurry containing a catalyst having carbon dioxide storage and reduction performance, and a second reaction containing the slurry. A step of supplying a reducing gas containing hydrogen to the reactor, a first flow path for transferring the slurry from the first reactor to the second reactor, and the second reactor from the second reactor. (1) A step of circulating the slurry between the first reactor and the second reactor by using a second flow path for transferring the slurry to the reactor is provided.

The present invention can be realized in various embodiments, for example, for controlling a methane production apparatus for producing methane from carbon dioxide and hydrogen, a methane production method, a methane production system, and control of these devices and systems. It can be realized in the form of a computer program, a server device for distributing the computer program, a non-temporary storage medium for storing the computer program, or the like.

It is a figure explaining the schematic structure of the methane production apparatus in 1st Embodiment. It is a figure which shows the time change of the amount of methane production. It is a figure explaining the schematic structure of the methane production apparatus in 2nd Embodiment. It is a figure explaining the schematic structure of the methane production apparatus in 3rd Embodiment. It is a figure explaining the schematic structure of the methane production apparatus in 4th Embodiment. It is a conceptual diagram of a pump flow rate map and a reduced gas flow rate map. It is a flowchart which shows the procedure of flow rate control by a control part.

<First Embodiment>
FIG. 1 is a diagram illustrating a schematic configuration of a methane production apparatus 1 according to the first embodiment. The methane production apparatus 1 of the present embodiment is an apparatus for producing methane (CH ₄ ) from carbon dioxide and hydrogen (H ₂ ) by using a catalyst having occlusal and reducing performance of carbon dioxide (CO ₂ ). The methane production apparatus 1 includes a first reactor 10, a second reactor 20, a raw material gas supply unit 15, a reducing gas supply unit 25, and a slurry pump 30.

In the methane production apparatus 1, a catalyst having CO ₂ occlusion and reduction performance (hereinafter, also simply referred to as “catalyst”) is used. For example, in the present embodiment, a catalyst containing at least one of an alkali metal that forms a carbonate to store CO ₂ , an alkaline earth metal, and a metal having a methanation catalytic performance. Can be used. In the methane production apparatus 1, a powdery catalyst mixed with a fluid such as silicon oil to form a slurry (hereinafter, also simply referred to as “slurry”) is used for occlusion and reduction of CO ₂ . do. That is, the catalyst used in the methane production apparatus 1 is in a fluid state (slurry).

The first reactor 10 is a reactor (container) for occluding CO ₂ contained in the raw material gas in the catalyst. The slurry is housed inside the first reactor 10. The first reactor 10 includes a supply pipe 11 through which the raw material gas from the raw material gas supply unit 15 flows, a discharge pipe 12 through which the exhaust gas (O ₂ , N ₂ , etc.) from the first reactor 10 flows. A second flow path forming unit 31 for transferring the slurry from the slurry pump 30 to the first reactor 10 and a first flow path forming unit for transferring the slurry from the first reactor 10 to the second reactor 20. The unit 13 and each are connected.

The second reactor 20 is a reactor (container) for the methanation reaction. Inside the second reactor 20, CH ₄ is generated by a Sabatier reaction using CO ₂ occluded in the slurry and H ₂ contained in the reducing gas. Similar to the first reactor 10, the slurry is housed inside the second reactor 20. The second reactor 20 includes a supply pipe 21 through which the reduced gas from the reducing gas supply unit 25 flows, a discharge pipe 22 through which the reaction mixed gas (CH ₄ or the like) in the second reactor 20 flows, and a first reactor. A first flow path forming unit 13 for transferring the slurry from the reactor 10 to the second reactor 20, and a second flow path forming unit 23 for transferring the slurry from the second reactor 20 to the slurry pump 30. And are connected respectively.

The sizes (diameter and height of the container) of the first reactor 10 and the second reactor 20 may be the same or different. The sizes of the first reactor 10 and the second reactor 20 are preferably determined according to the characteristics of the catalyst. For example, when the reduction rate of CO ₂ is slower than the occlusion rate, the first reactor 10 is used. It is preferable to design the size of the second reactor 20 to be larger than that of the second reactor 20. Then, the time that the catalyst stays in the second reactor 20 can be made longer than the time that the catalyst stays in the first reactor 10.

The raw material gas supply unit 15 is a device for supplying the raw material gas to the first reactor 10, and is composed of, for example, a combustion furnace or a raw material gas tank. The raw material gas may contain oxygen (O ₂ ), nitrogen (N ₂ ) and the like in addition to CO ₂ used for the generation of CH ₄ . A supply pipe 11 through which the raw material gas flows from the raw material gas supply unit 15 to the first reactor 10 is connected to the raw material gas supply unit 15. The raw material gas supply unit 15 of the present embodiment constantly supplies the raw material gas to the first reactor 10. Therefore, the supply pipe 11 does not have to be provided with a mechanism (valve or the like) for switching between supply and cutoff of the raw material gas.

The reducing gas supply unit 25 is a device that supplies the reducing gas to the second reactor 20, and is composed of, for example, a water electrolyzer and a hydrogen tank. The reducing gas may contain N ₂ and the like in addition to H ₂ used for the generation of CH ₄ . A supply pipe 21 through which the reducing gas flows from the reducing gas supply unit 25 to the second reactor 20 is connected to the reducing gas supply unit 25. The reducing gas supply unit 25 of the present embodiment constantly supplies the reducing gas to the second reactor 20. Therefore, similarly to the supply pipe 11, the supply pipe 21 does not have to be provided with a mechanism (valve or the like) for switching between supply and cutoff of the reducing gas.

The slurry pump 30 is provided on the second flow path and transfers the slurry in the direction of the white arrow and the broken line hatching arrow (FIG. 1) between the first reactor 10 and the second reactor 20. It is a pump that circulates the slurry in. The "first flow path" is a flow path for transferring the slurry from the first reactor 10 to the second reactor 20, and is formed by the first flow path forming portion 13 (FIG. 1: 1). White arrow). The "second flow path" is a flow path for transferring the slurry from the second reactor 20 to the first reactor 10, and is formed by the second flow path forming portion 23 and the second flow path forming portion 31. (Fig. 1: Diagonal hatched arrow).

A methane production method using the methane production apparatus 1 will be described. As described above, the first reactor 10 and the second reactor 20 each contain a catalyst having CO ₂ occlusion and reduction performance. First, in the first reactor 10, CO ₂ contained in the raw material gas supplied from the raw material gas supply unit 15 is occluded in the catalyst. Other components (for example, O ₂ , N ₂ , etc.) contained in the raw material gas are discharged from the discharge pipe 12 as exhaust gas. The exhaust gas may be released to the outside, or may be separated into gas types and stored in a gas tank (not shown).

The catalyst in which CO ₂ is occluded is transferred from the first reactor 10 to the second reactor 20 through the first flow path (FIG. 1: white arrow) by the slurry pump 30. That is, the second reactor 20 is supplied with a catalyst in which CO ₂ is occluded.

Next, in the second reactor 20, H ₂ contained in the reducing gas supplied from the reducing gas supply unit 25 reacts with CO ₂ occluded in the catalyst (Sabatier reaction) to contain CH ₄ . A mixed gas is produced. The reaction mixed gas is discharged from the discharge pipe 22, is separated as it is or by gas type, and is stored in a gas tank (not shown).

After the CO ₂ has been occluded, the catalyst is transferred from the second reactor 20 to the first reactor 10 again through the second flow path (FIG. 1: diagonal hatching arrow) by the slurry pump 30. .. That is, the catalyst in a state where CO ₂ is not occluded is supplied to the first reactor 10.

As described above, in the methane production apparatus 1 of the present embodiment, the catalyst contained in the first and second reactors 10 and 20 is made into a flowable slurry, and the first and second flow path forming portions 13, 23, 31 are formed. And the slurry pump 30 circulates the slurry between the first reactor 10 for occluding CO ₂ in the catalyst and the second reactor 20 for the methanation reaction. Therefore, in the methane production apparatus 1 of the present embodiment, as in the conventional case, the step of occluding carbon dioxide (CO ₂ ) from the raw material gas and the methane of CO ₂ using the reducing gas in a single reactor. It is not necessary to carry out both the (CH ₄ ) conversion step, and the same gas can always be supplied to the first and second reactors 10 and 20 respectively. As a result, according to the methane production apparatus 1 of the present embodiment, the apparatus configuration of the methane production apparatus 1 can be simplified because the switching of the gas to the reactor and the accompanying large number of valves are not required.

FIG. 2 is a diagram showing the time variation of the amount of methane (CH ₄ ) produced. The vertical axis represents the amount of CH ₄ produced [mol / min], and the horizontal axis represents time. FIG. 2 shows a change S in the amount of CH ₄ produced by the methane production apparatus 1 of the present embodiment, a change S1 in the amount of CH ₄ produced by the methane production apparatus of the first comparative example, and the methane production apparatus of the second comparative example. Changes in the amount of CH ₄ produced S2 (1) and (2) are shown. In the first comparative example, the first step of occluding CO ₂ from the raw material gas and the occluded CO ₂ in a single reactor containing a solid catalyst layer having occluding and reducing performance of CO ₂ are carried out. It is a methane production apparatus that sequentially carries out the second step of reducing to produce CH ₄ . The second comparative example is a methane production apparatus having the same configuration as the first comparative example and having a multi-stage reactor.

As is clear from the change S1 (dashed-dotted line) in FIG. 2, in the first comparative example, CH ₄ is performed during the time t _n to t _{n + 1} during which the first step of occluding CO ₂ from the raw material gas is executed. Is not generated. In addition, "n" means an arbitrary time after the start of processing. Further, in the first comparative example, the amount of methane produced is parabolic even during the time t _{n + 1} to t _{n + 2} when the second step of reducing the occluded CO ₂ to generate CH ₄ is executed. And does not take a certain value. This is because there is a time delay between opening and closing the valve for supplying the reducing gas and the time when the flow rate of the reducing gas stabilizes, and the total amount and distribution of CO ₂ occluded in the catalyst layer with the passage of time. It is caused by the change in the gas.

In FIG. 2, the change S2 (1) shown by the broken line represents the amount of methane produced by the first-stage reactor of the second comparative example, and the change S2 (2) is due to the second-stage reactor of the second comparative example. Represents the amount of methane produced. By increasing the number of stages of the reactor and shifting the timing of the first and second steps, for example, CH ₄ is generated by the first stage reactor between the time t _n and t _n + 1, and from the time t _{n + 1} . During t _{n + 2} , continuous processing such as generating CH ₄ by the second-stage reactor is possible. However, also in the second comparative example, as in the first comparative example, the amount of methane produced in each reactor is parabolic and does not take a constant value. The reason is as described above. In addition, when the reactor is multi-staged, the raw material gas can be continuously treated as described above, but the total amount and distribution of CO ₂ occluded in the catalyst layer changes with the passage of time. , Changes in the amount of methane produced S2 (1) and S2 (2) do not necessarily have the same trajectory.

On the other hand, in the methane production apparatus 1 of the present embodiment, as described above, since it is not necessary to switch the gas to the reactor, the flow rate of the raw material gas from the raw material gas supply unit 15 to the first reactor 10 and the flow rate of the raw material gas. The flow rate of the reduced gas from the reducing gas supply unit 25 to the second reactor 20 can be stabilized. Further, the catalyst housed in the first and second reactors 10 and 20 is in the form of a flowable slurry. Therefore, the slurry flows not only between the first and second reactors 10 and 20 but also inside each of the reactors 10 and 20, so that the total amount and distribution of CO ₂ occluded in the catalyst are made uniform. At the same time, the temperature inside the reactor can be made uniform. As a result, in the methane production apparatus 1 of the present embodiment, as is clear from the change S (solid line) in FIG. 2, the amount of methane produced can be stabilized. That is, in the methane production apparatus 1 of the present embodiment, steady generation of CH ₄ , which was difficult with the conventional configuration, can be realized, and robustness against load fluctuation can be improved.

As described above, according to the methane production apparatus 1 of the present embodiment, in the production of methane using a catalyst having CO ₂ occlusion and reduction performance, the apparatus configuration is simplified and the amount of methane produced is stabilized. be able to. Further, according to the methane production apparatus 1, the residence time of the catalyst in the first and second reactors 10 and 20 can be controlled by changing the flow rate of the slurry pump 30. Therefore, for example, even if the flow rate or composition (CO ₂ content) of the raw material gas supplied from the raw material gas supply unit 15 to the first reactor 10 changes, the target CO ₂ in the first reactor 10 is changed. The residence time required to achieve the recovery rate can be easily secured.

<Second Embodiment>
FIG. 3 is a diagram illustrating a schematic configuration of the methane production apparatus 1a according to the second embodiment. In the second embodiment, a configuration capable of discharging the gas remaining in the catalyst moving to the next reactor will be described. The methane production apparatus 1a of the second embodiment further includes a third reactor 40, a fourth reactor 50, a first purge gas supply unit 45, and a second purge gas in addition to the configurations of the first embodiment described above. It is provided with a supply unit 55. Hereinafter, the parts different from the first embodiment will be described.

The third reactor 40 is provided on the first flow path, and gas (O ₂ , N ₂ , etc.) remaining in the catalyst contained in the slurry transferred from the first reactor 10 to the second reactor 20 is removed. It is a reactor (container) for discharging. Similar to the first reactor 10, the slurry is housed inside the third reactor 40. The third reactor 40 includes a supply pipe 41 through which the purge gas from the first purge gas supply unit 45 flows, a discharge pipe 42 through which the exhaust gas from the third reactor 40 flows, and a first reactor 10 to a third reactor. The first flow path forming unit 13a for transferring the slurry to the reactor 40 and the first flow path forming unit 43 for transferring the slurry from the third reactor 40 to the second reactor 20, respectively. It is connected.

The fourth reactor 50 is provided on the second flow path to discharge the gas (H ₂ , etc.) remaining in the catalyst contained in the slurry transferred from the second reactor 20 to the first reactor 10. Reactor (container). Similar to the first reactor 10, the slurry is housed inside the fourth reactor 50. The fourth reactor 50 includes a supply pipe 51 through which the purge gas from the second purge gas supply unit 55 flows, a discharge pipe 52 through which the exhaust gas from the fourth reactor 50 flows, and the second reactor 20 to the fourth. A second flow path forming unit 23a for transferring the slurry to the reactor 50 and a second flow path forming unit 53 for transferring the slurry from the fourth reactor 50 to the slurry pump 30 are connected, respectively. ing.

The first purge gas supply unit 45 is a device that supplies purge gas to the third reactor 40, and is composed of, for example, a nitrogen gas generator and a nitrogen tank. The purge gas may contain CO ₂ , O ₂ , and the like in addition to N ₂ used for discharging residual gas. A supply pipe 41 through which purge gas flows from the first purge gas supply unit 45 to the third reactor 40 is connected to the first purge gas supply unit 45. The first purge gas supply unit 45 of the present embodiment constantly supplies the purge gas to the third reactor 40. Therefore, similarly to the supply pipe 11, the supply pipe 41 may not be provided with a mechanism (valve or the like) for switching between supply and cutoff of purge gas. The second purge gas supply unit 55 is a device that supplies purge gas to the fourth reactor 50, and the details are the same as those of the first purge gas supply unit 45. A supply pipe 51 through which purge gas flows from the second purge gas supply unit 55 to the fourth reactor 50 is connected to the second purge gas supply unit 55.

In the second embodiment, the first flow path forming portion 13a and the first flow path forming portion 43 form a "first flow path", and the second flow path forming portion 23a, the second flow path forming portion 53, and the second flow path forming portion 53 are formed. The two flow path forming portions 31 form a "second flow path". In the above-described configuration, at least one of the third reactor 40 and the first purge gas supply unit 45 and the fourth reactor 50 and the second purge gas supply unit 55 may be omitted. Further, the first purge gas supply unit 45 and the second purge gas supply unit 55 may be configured by a single purge gas supply unit. In this case, both the supply pipe 41 for supplying the purge gas to the third reactor 40 and the supply pipe 51 for supplying the purge gas to the fourth reactor 50 are connected to a single purge gas supply unit.

As described above, the methane production apparatus 1a of the second embodiment can exhibit the same effect as that of the first embodiment described above. Further, in the methane production apparatus 1a of the second embodiment, the gas (O ₂ , N ₂ , etc.) remaining in the catalyst contained in the slurry transferred on the first flow path is discharged by using the third reactor 40. can. Further, the fourth reactor can be used to discharge the gas (H ₂ , N ₂ , etc.) remaining in the catalyst contained in the slurry transferred on the second flow path. As a result, in the methane production apparatus 1a of the second embodiment, it is possible to suppress the mixture of O ₂ and H ₂ in the first and second reactors 10 and 20.

<Third Embodiment>
FIG. 4 is a diagram illustrating a schematic configuration of the methane production apparatus 1b according to the third embodiment. In the third embodiment, as in the second embodiment, a configuration capable of discharging the gas remaining in the catalyst moving to the next reactor will be described. The methane production apparatus 1b of the third embodiment further includes a first gas-liquid separator 60 and a second gas-liquid separator 70 in addition to the configurations of the first embodiment described above.

The first gas-liquid separator 60 is provided on the first flow path, and the gas (O ₂ , N ₂ , etc.) remaining in the catalyst contained in the slurry transferred from the first reactor 10 to the second reactor 20 is provided. ) Is a gas-liquid separator for separating and discharging. Similar to the first reactor 10, the slurry is housed inside the first gas-liquid separator 60. The first gas-liquid separator 60 includes a first flow path forming portion 13b for transferring the slurry from the first reactor 10 to the first gas-liquid separator 60, and a second gas-liquid separator 60 to the second. A first flow path forming portion 61 for transferring the slurry to the reactor 20 is connected to each of them.

The second gas-liquid separator 70 is provided on the second flow path, and the gas (H ₂ , N ₂ , etc.) remaining in the catalyst contained in the slurry transferred from the second reactor 20 to the first reactor 10 is provided. ) Is a gas-liquid separator for separating and discharging. Similar to the first reactor 10, the slurry is housed inside the second gas-liquid separator 70. The second gas-liquid separator 70 includes a second flow path forming unit 23b for transferring the slurry from the second reactor 20 to the second gas-liquid separator 70, and a slurry pump from the second gas-liquid separator 70. A second flow path forming portion 71 for transferring the slurry to 30 is connected to each of the second flow path forming portions 71.

In the third embodiment, the first flow path forming portion 13b and the first flow path forming portion 61 form a "first flow path", and the second flow path forming portion 23b, the second flow path forming portion 71, and the second flow path forming portion 71 are formed. The two flow path forming portions 31 form a "second flow path". In the above-described configuration, at least one of the first gas-liquid separator 60 and the second gas-liquid separator 70 may be omitted.

As described above, the methane production apparatus 1b of the third embodiment can exhibit the same effect as that of the first embodiment described above. Further, in the methane production apparatus 1b of the third embodiment, the gas (O ₂ , N ₂ , etc.) remaining in the catalyst contained in the slurry transferred on the first flow path is used by using the first gas-liquid separator 60. Can be discharged. Further, the second gas-liquid separator 70 can be used to discharge the gas (H ₂ , N ₂ , etc.) remaining in the catalyst contained in the slurry transferred on the second flow path. As a result, even in the methane production apparatus 1b of the third embodiment, it is possible to suppress the mixture of O ₂ and H ₂ in the first and second reactors 10 and 20.

<Fourth Embodiment>
FIG. 5 is a diagram illustrating a schematic configuration of the methane production apparatus 1c according to the fourth embodiment. In the fourth embodiment, a configuration capable of controlling the flow rate of the slurry pump 30 and the supply amount of the reducing gas from the reducing gas supply unit 25 will be described. The methane production apparatus 1c of the fourth embodiment further includes a first flow meter 91, a second flow meter 92, a first densitometer 95, and a second densitometer in addition to the configurations of the first embodiment described above. It includes 96, a mass flow controller 80, and a control unit 100.

The first flow meter 91 is a flow rate sensor that measures the flow rate of the raw material gas supplied from the raw material gas supply unit 15 to the first reactor 10, and is provided in the supply pipe 11. Various types can be adopted for the first flow meter 91, for example, a Karman vortex type, a thermal type, an ultrasonic type and the like can be adopted. The first flow meter 91 functions as a "first flow rate acquisition unit" for acquiring the flow rate of the raw material gas. When the control unit 100 can acquire information on the flow rate of the raw material gas from a device (for example, a combustion furnace or a raw material gas tank) constituting the raw material gas supply unit 15, the control unit 100 is made to function as the first flow rate acquisition unit. Therefore, the first flow meter 91 may be omitted.

The first densitometer 95 is a concentration sensor that measures the CO ₂ concentration of the raw material gas supplied from the raw material gas supply unit 15 to the first reactor 10, and is a gas ejection port of the raw material gas supply unit 15 in the supply pipe 11. It is provided in the vicinity of. The first densitometer 95 functions as a "first concentration acquisition unit" for acquiring the CO ₂ concentration in the raw material gas. When the control unit 100 can acquire information on the CO ₂ concentration in the raw material gas from the device constituting the raw material gas supply unit 15, the control unit 100 is made to function as the first concentration acquisition unit, and the first densitometer is used. 95 may be omitted.

The second flow meter 92 is a flow rate sensor that measures the flow rate of the exhaust gas discharged from the first reactor 10, and is provided in the discharge pipe 12. The second flow meter 92 can adopt various types like the first flow meter 91. The second flow meter 92 functions as a "second flow rate acquisition unit" that acquires the flow rate of the exhaust gas. The second densitometer 96 is a concentration sensor that measures the CO ₂ concentration in the exhaust gas discharged from the first reactor 10, and is provided in the discharge pipe 12 in the vicinity of the gas ejection port of the first reactor 10. There is. The second densitometer 96 functions as a "second concentration acquisition unit" that acquires the CO ₂ concentration in the exhaust gas.

The mass flow controller 80 includes a flow rate sensor, a flow rate control valve, and the like (not shown), and is a device that controls the flow rate of the reduced gas supplied from the reduced gas supply unit 25 to the second reactor 20, and is provided in the supply pipe 21. ing.

The control unit 100 is a computer including a ROM, a RAM, and a CPU, and controls each unit of the methane production apparatus 1c. The control unit 100 is electrically connected to the first and second flowmeters 91 and 92 and the first and second densitometers 95 and 96, and acquires the measured values of each flowmeter and each densitometer. Further, the control unit 100 is electrically connected to the slurry pump 30 and the mass flow controller 80, and controls the slurry pump 30 and the mass flow controller 80. The control unit 100 stores in advance a pump flow rate map 101 used for controlling the slurry pump 30 and a reduced gas flow rate map 102 used for controlling the mass flow controller 80.

FIG. 6 is a conceptual diagram of the pump flow rate map 101 and the reducing gas flow rate map 102. FIG. 6A shows a conceptual diagram of the pump flow rate map 101. In the pump flow rate map 101, the vertical axis represents the CO ₂ concentration (X _CO2 _ _in ) in the raw material gas, and the horizontal axis represents the flow rate of the raw material gas (Q _in [slm]). The shade of the map represents the flow rate of the slurry pump 30, and the darker the color, the higher the flow rate of the slurry pump 30, and the lighter the color, the lower the flow rate of the slurry pump 30.

The higher the CO ₂ concentration in the raw material gas and the larger the flow rate of the raw material gas supplied to the first reactor 10 per unit time, the longer it takes for the catalyst to occlude CO ₂ . The flow rate of the slurry pump 30 needs to be reduced. Therefore, in the pump flow rate map 101, the flow rate of the slurry pump 30 is inversely proportional to both the CO ₂ concentration in the raw material gas and the flow rate of the raw material gas. The pump flow rate map 101 is obtained in advance by an experiment or the like, and is stored in a storage unit (ROM or the like) in the control unit 100.

FIG. 6B shows a conceptual diagram of the reduced gas flow rate map 102. In the reduced gas flow rate map 102, the vertical axis represents the CO ₂ recovery amount (Q _ad [slm]) in the first reactor 10, and the horizontal axis represents the flow rate (Q _s [slm]) of the slurry pump 30. The shade of the map represents the flow rate of the reducing gas controlled by the mass flow controller 80, and the darker the color, the larger the flow rate of the reducing gas, and the lighter the color, the smaller the flow rate of the reducing gas.

The amount of CO ₂ recovered in the first reactor 10 (the amount of CO ₂ occluded in the catalyst) means the amount of CO ₂ requiring reduction in the second reactor 20. The flow rate of the slurry pump 30 means the amount of catalyst supplied to the second reactor 20 per unit time. Therefore, the larger the amount of CO ₂ recovered in the first reactor 10 and the larger the flow rate of the slurry pump 30, the more H ₂ for CO ₂ reduction is consumed, so that the flow rate of the reducing gas is increased. Need to be increased. Therefore, in the reduced gas flow rate map 102, the flow rate of the reduced gas is proportional to both the CO ₂ recovery amount in the first reactor 10 and the flow rate of the slurry pump 30. Similar to the pump flow rate map 101, the reduced gas flow rate map 102 is obtained in advance by an experiment or the like and is stored in a storage unit (ROM or the like) in the control unit 100.

The pump flow rate map 101 and the reducing gas flow rate map 102 shown in FIG. 6 show the CO ₂ occlusion rate and reduction rate in the catalyst used, the sizes of the first reactor 10 and the second reactor 20 used, and the target. It varies depending on the recovery rate of CO ₂ and the composition of the raw material gas and the reducing gas. Therefore, if it is desired to change each of these conditions in the subsequent flow rate control, the pump flow rate map 101 and the reducing gas flow rate map 102 need to be recreated.

FIG. 7 is a flowchart showing a flow rate control procedure by the control unit 100. The flow rate control is executed after the operation of the methane production apparatus 1c is started, and is constantly executed during the operation of the methane production apparatus 1c. In the following description, a combustion furnace will be illustrated as the raw material gas supply unit 15, and a case where the CO ₂ concentration in the raw material gas and the flow rate of the raw material gas constantly fluctuate will be illustrated.

In step S10, the control unit 100 initializes the time variable t [seconds] used for control to 0. In step S12, the control unit 100 has a flow rate Q _in (t) [slm] of the raw material gas measured by the first flow meter 91 and a CO ₂ concentration X _CO2 _ in the raw material gas measured by the first densitometer 95. _In (t) and get. In step S14, the control unit 100 refers to the pump flow rate map 101 and obtains the flow rate Q _s (t) [slm] of the slurry pump 30 using each acquired value in step S12. In step S16, the control unit 100 changes the flow rate of the slurry pump 30 to the flow rate Q _s (t) obtained in step S14.

In step S18, the control unit 100 has a flow rate Q _out (t) [slm] of the exhaust gas from the first reactor 10 measured by the second flow meter 92 and a first reaction measured by the second densitometer 96. Obtain the CO ₂ concentration X _CO2 _ _out (t) in the exhaust gas from the reactor 10. In step S20, the control unit 100 obtains the CO ₂ recovery amount Q _ad (t) [slm] in the first reactor 10 from the following mathematical formula 1 using each acquired value in step S18.

In step S22, the control unit 100 refers to the reduced gas flow rate map 102, and obtains the CO ₂ recovery amount Q _ad (t) obtained in step S20 and the flow rate Q _s (t) of the slurry pump 30 obtained in step S14. The flow rate Q _r (t) [slm] of the reducing gas is obtained by using. In step S24, the control unit 100 changes the flow rate of the reducing gas from the mass flow controller 80 to the flow rate Q _r (t) obtained in step S22.

In step S26, the control unit 100 determines whether or not the first time (Δt) [seconds] has elapsed. The first time Δt can be arbitrarily determined in advance, and can be, for example, an arbitrary value of about 0.1 to 5 seconds. If the first time has not elapsed (step S26: NO), the control unit 100 shifts the process to step S26 and monitors the elapse of the first time. When the first time has elapsed (step S26: YES), the control unit 100 shifts the process to step S28.

In step S28, the control unit 100 sets the flow rate Q _in (t + Δt) of the raw material gas after the lapse of the first time and the CO ₂ concentration X _CO2 _ _in (t + Δt) in the raw material gas into the first flow meter 91 and the first. Obtained from densitometer 95. In step S30, the control unit 100 increases or decreases the flow rate Q _in (t + Δt) of the raw material gas after the lapse of the first time from each acquired value in step S12 and each acquired value in step S28, and the first time elapses. It is determined whether or not the condition shown in the following formula 2 is satisfied for the increase / decrease of the CO ₂ concentration X _CO2 _ _in (t + Δt) in the raw material gas. Here, α is a threshold value representing the increase / decrease amount [%] of the flow rate and the concentration, and can be any value of, for example, about 1 to 20. In Equation 2, the same threshold value α is used for increasing / decreasing the flow rate Q _in (t + Δt) of the raw material gas and increasing / decreasing the CO ₂ concentration X _CO2 _ _in (t + Δt) in the raw material gas, but these have different threshold values. It may be used.

When the condition shown in Equation 2 is satisfied (step S30: YES), the control unit 100 shifts the process to step S14, and the flow rate Q _in (t + Δt) of the raw material gas after the lapse of the first time and CO ₂ in the raw material gas. The flow rate Q _s (t + Δt) of the slurry pump 30 is obtained based on the concentration X _CO2 _ _in (t + Δt), and the flow rate of the slurry pump 30 is changed. After that, the control unit 100 continues the processing after step S16.

On the other hand, when the condition shown in the equation 2 is not satisfied (step S30: NO), the control unit 100 shifts the process to step S32 and determines whether or not the second time (Δt _w ) [seconds] has elapsed. The second time Δt _w can be arbitrarily determined in advance, and can be, for example, an arbitrary value of about 30 to 600 seconds. If the second time has not elapsed (step S32: NO), the control unit 100 shifts the process to step S32 and monitors the elapse of the second time. When the second time has elapsed (step S32: YES), the control unit 100 shifts the process to step S28, and again, using the acquired values of the first flow meter 91 and the first densitometer 95 at that time, It is determined whether or not the condition shown in Equation 2 is satisfied.

As described above, the methane production apparatus 1c of the fourth embodiment can exhibit the same effect as that of the first embodiment described above. Further, according to steps S12 to S16 of the flow rate control of the methane production apparatus 1c (FIG. 7), the control unit 100 has a CO ₂ concentration in the raw material gas acquired by the first concentration meter 95 (first concentration acquisition unit). And the flow rate of the raw material gas acquired by the first flow meter 91 (first flow rate acquisition unit) is inversely proportional to both, and the flow rate of the pump is changed (FIG. 6A). Therefore, according to the methane production apparatus 1c of the fourth embodiment, the catalyst can be allowed to stay in the first reactor 10 for a period of time until CO ₂ is sufficiently occluded in the catalyst in the first reactor 10. As a result, the amount of CO ₂ recovered in the first reactor 10 can be improved.

Further, according to steps S18 to S24 of the flow rate control of the methane production apparatus 1c (FIG. 7), the control unit 100 has the CO ₂ concentration in the raw material gas acquired by the first concentration meter 95 (first concentration acquisition unit). From the "CO ₂ amount in the raw material gas" obtained from the flow rate of the raw material gas acquired by the first flow meter 91 (first flow rate acquisition unit), the second densitometer 96 (second concentration acquisition unit) By reducing the "amount of carbon dioxide in the exhaust gas" obtained from the CO ₂ concentration in the acquired exhaust gas and the flow rate of the exhaust gas acquired by the second flow meter 92 (second flow rate acquisition unit) ( Equation 1), the CO ₂ recovery amount Q _ad in the first reactor 10 is obtained. The control unit 100 changes the flow rate of the mass flow controller 80 in proportion to both the obtained CO ₂ recovery amount in the first reactor 10 and the flow rate of the slurry pump 30, and thereby the raw material gas supply unit 15. Change the supply amount of reducing gas. Therefore, according to the methane production apparatus 1c of the fourth embodiment, it is possible to supply a sufficient amount of H ₂ for the reduction of CO ₂ in the second reactor 20 each time. As a result, the amount of methane produced in the second reactor 20 can be improved, and the amount of reduced gas consumed can be suppressed.

The control content of the control unit 100 described with reference to FIG. 7 is merely an example. The control unit 100 acquired the flow rate Q _in of the raw material gas acquired from the first flow meter 91, the CO ₂ concentration X _CO2 _ _{in in} the raw material gas acquired from the first concentration meter 95, and the second flow meter 92. At least a part of the flow rate Q _out of the exhaust gas from the first reactor 10 and the CO ₂ concentration X _CO2 _ _out in the exhaust gas from the first reactor 10 acquired from the second densitometer 96. It can be used to perform various controls on the slurry pump 30 and the mass flow controller 80. For example, the control unit 100 may control the drive and stop of the slurry pump 30 instead of changing the flow rate of the slurry pump 30. For example, the control unit 100 may change the concentration and composition of the reducing gas instead of changing the flow rate of the reducing gas, or may change the flow rate, concentration, and composition of the raw material gas. By doing so, it is possible to further stabilize the amount of methane produced in the production of methane using a catalyst having CO ₂ occlusion and reduction performance.

<Modified example of this embodiment>
The present invention is not limited to the above embodiment, and can be carried out in various embodiments without departing from the gist thereof, and for example, the following modifications are also possible.

[Modification 1]
In the first to fourth embodiments, an example of the configuration of the methane production apparatus is shown. However, the configuration of the methane production apparatus can be modified in various ways. For example, a plurality of at least one of the first reactor and the second reactor may be provided. When a plurality of first reactors or second reactors are provided, the connections of these reactors may be in series or in parallel. For example, when a plurality of second reactors are provided in series, for example, a gas-liquid separator is provided between the second reactor in the first stage and the second reactor in the second stage from the reaction mixed gas. H ₂ O may be separated. For example, in the methane production apparatus of the fourth embodiment, a mass flow controller for controlling the flow rate of the raw material gas may be provided in the supply pipe from the raw material gas supply unit to the first reactor.

[Modification 2]
In the fourth embodiment, an example of the control contents by the control unit of the methane production apparatus is shown. However, the content of control by the control unit can be modified in various ways. For example, at least one of the flow rate control of the slurry pumps in steps S12 to S16 and the flow rate control of the reducing gas in steps S18 to S24 may be omitted. When the flow rate control of the reducing gas in steps S18 to S24 is omitted, the mass flow controller may be omitted from the methane production apparatus shown in FIG. For example, further processing that is not explained may be added. As further processing, for example, control of the flow rate of the raw material gas, control of the concentration of the reducing gas, control of the composition of the reducing gas, and the like can be adopted.

[Modification 3]
The configurations of the methane production equipment of the first to fourth embodiments and the configurations of the methane production equipment of the above-mentioned modifications 1 and 2 may be appropriately combined. For example, the methane production apparatus of the second and third embodiments is configured to include the first and second flowmeters, the first and second densitometers, and the control unit, and the control unit described in the fourth embodiment is used for control. May be good. For example, the methane production apparatus of the second embodiment may further include the gas-liquid separator described in the third embodiment.

Although this embodiment has been described above based on the embodiments and modifications, the embodiments described above are for facilitating the understanding of the present embodiment and do not limit the present embodiment. This aspect may be modified or improved without departing from its spirit and claims, and this aspect includes its equivalent. Further, if the technical feature is not described as essential in the present specification, it may be deleted as appropriate.

1,1a-1c ... Methane production equipment 10 ... 1st reactor 11 ... Supply pipe 12 ... Discharge pipe 13, 13a, 13b ... 1st flow path forming part 15 ... Raw material gas supply part 20 ... 2nd reactor 21 ... Supply Pipe 22 ... Discharge pipes 23, 23a, 23b ... Second flow path forming part 25 ... Reducing gas supply part 30 ... Slurry pump 31 ... Second flow rate forming part 40 ... Third reactor 41 ... Supply pipe 42 ... Discharge pipe 43 ... 1st flow path forming part 45 ... 1st purge gas supply part 50 ... 4th reactor 51 ... Supply pipe 52 ... Discharge pipe 53 ... 2nd flow rate forming part 55 ... 2nd purge gas supply part 60 ... 1st gas-liquid separation Instrument 61 ... 1st flow path forming part 70 ... 2nd gas-liquid separator 71 ... 2nd flow path forming part 80 ... Mass flow controller 91 ... 1st flow meter 92 ... 2nd flow meter 95 ... 1st densitometer 96 ... 2 Densitometer 100 ... Control unit 101 ... Pump flow rate map 102 ... Reduced gas flow rate map

Claims (8)

A methane production device that produces methane from carbon dioxide and hydrogen.
A first reactor and a second reactor containing a slurry containing a catalyst having carbon dioxide occlusion and reduction performance, and
A raw material gas supply unit that supplies a raw material gas containing carbon dioxide to the first reactor,
A reducing gas supply unit that supplies a reducing gas containing hydrogen to the second reactor,
A first flow path forming portion that forms a first flow path for transferring the slurry containing the catalyst that has occluded carbon dioxide from the first reactor to the second reactor.
A second flow path for transferring the slurry containing the catalyst after the occluded carbon dioxide is used in the reaction with hydrogen is formed from the second reactor to the first reactor. Channel forming part and
A pump that circulates the slurry between the first reactor and the second reactor,
Equipped with a methane production device. The methane production apparatus according to claim 1, further
The first concentration acquisition unit for acquiring the carbon dioxide concentration in the raw material gas,
The first flow rate acquisition unit that acquires the flow rate of the raw material gas,
A second concentration acquisition unit that acquires the carbon dioxide concentration in the exhaust gas discharged from the first reactor, and
A second flow rate acquisition unit that acquires the flow rate of the exhaust gas discharged from the first reactor, and
The pump and the reducing gas supply according to at least a part of the acquired values by the first concentration acquisition unit, the first flow rate acquisition unit, the second concentration acquisition unit, and the second flow rate acquisition unit. A control unit that controls at least one of the reducing gas from the unit,
Equipped with a methane production device. The methane production apparatus according to claim 2.
The control unit is inversely proportional to both the carbon dioxide concentration in the raw material gas acquired by the first concentration acquisition unit and the flow rate of the raw material gas acquired by the first flow rate acquisition unit. A methane production device that changes the flow rate of a pump. The methane production apparatus according to claim 2 or 3.
The control unit
From the amount of carbon dioxide in the raw material gas obtained from the carbon dioxide concentration in the raw material gas acquired by the first concentration acquisition unit and the flow rate of the raw material gas acquired by the first flow rate acquisition unit, the said By reducing the amount of carbon dioxide in the exhaust gas obtained from the carbon dioxide concentration in the exhaust gas acquired by the second concentration acquisition unit and the flow rate of the exhaust gas acquired by the second flow rate acquisition unit. , Obtained the amount of carbon dioxide recovered in the first reactor,
A methane production apparatus that changes the supply amount of the reduced gas from the reduced gas supply unit in proportion to both the obtained carbon dioxide recovery amount and the flow rate of the pump. The methane production apparatus according to any one of claims 1 to 4, further comprising.
A third reactor provided on the first flow path and accommodating the slurry, and
A fourth reactor provided on the second flow path and accommodating the slurry, and
Equipped with at least one of
A purge gas supply unit that supplies purge gas to at least one of the third reactor and the fourth reactor.
Equipped with a methane production device. The methane production apparatus according to any one of claims 1 to 5, further comprising.
The first gas-liquid separator provided on the first flow path and
A second gas-liquid separator provided on the second flow path, and
A methane production device comprising at least one of the following. The methane production apparatus according to any one of claims 1 to 6.
The catalyst is a methane production apparatus containing at least one of an alkali metal that forms a carbonate and stores carbon dioxide, an alkaline earth metal, and a metal having a methanation catalytic performance. A methane production method that produces methane from carbon dioxide and hydrogen.
A step of supplying a raw material gas containing carbon dioxide to a first reactor containing a slurry containing a catalyst having carbon dioxide occluding and reducing performance, and causing the catalyst to occlude carbon dioxide .
A step of supplying a reducing gas containing hydrogen to the second reactor containing the slurry and reacting the hydrogen with the occluded carbon dioxide to generate methane .
A first flow path for transferring the slurry from the first reactor to the second reactor, and a second flow path for transferring the slurry from the second reactor to the first reactor. And, a step of circulating the slurry between the first reactor and the second reactor, and
A methane production method.

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