JP7407673B2 - Hydrocarbon production system - Google Patents

Description

The present invention relates to a hydrocarbon production system.

Conventionally, there is a known technology for separating carbon dioxide from a mixed gas containing multiple types of gases using a catalyst that stores carbon dioxide, and producing hydrocarbons as fuel from the separated carbon dioxide (for example, (See Patent Document 1). Patent Document 1 discloses a technique in which methane is produced using a methanation catalyst and a carbon dioxide storage component housed in one reactor.

Patent Document 2 describes a methane production system including a plurality of reactors. In this system, exhaust gas (exhaust gas) from one reactor can be supplied to other reactors, and methane is continuously produced in multiple reactors, and a mixed gas with a high methane concentration is produced. Manufactured. The methane production system disclosed in Patent Document 3 includes a plurality of reactors, and switches the reactor for supplying a mixed gas containing carbon dioxide depending on the concentration of carbon dioxide in the exhaust gas of the reactor. In the methane production apparatus described in Patent Document 4, a catalyst for purifying nitrogen oxides and a component for storing nitrogen oxides are housed in a reactor, and nitrogen oxides are also removed together with carbon dioxide in the exhaust gas of the reactor. has been removed. Non-Patent Documents 1 and 2 describe the use of Ru as a methanation catalyst, CaO as a carbon dioxide storage component, and Al ₂ O ₃ as a carrier. Non-Patent Document 3 describes the use of Ca and Na as carbon dioxide storage components.

International Publication No. 2016/007825 Japanese Patent Application Publication No. 2019-108290 Japanese Patent Application Publication No. 2019-108302 JP2019-210260A

Melis S. Duyar, Martha A. Arellano Trevino, Robert J. Farrauto, "Dual function materials for CO2 capture and conversion using renewable H2", Applied Catalysis B: Environmental, June 2015, Volumes 168-169, Pages 370-376 Shuoxun Wang, Erik T. Schrunk, Harshit Mahajan and And Robert J. Farrauto, "The Role of Ruthenium in CO2 Capture and Catalytic Conversion to Fuel by Dual Function Materials (DFM)", Catalysts 2017 7(3) 88 A. Bermejo-Lopez, B. Pereda-Ayo, J.A. Gonzalez-Marcos, J.R. Gonzalez-Velasco, "Mechanism of the CO2 storage and in situ hydrogenation to CH4. Temperature and adsorbent loading effects over Ru-CaO/Al2O3 and Ru-Na2CO3 /Al2O3 catalysts", Applied Catalysis B: Environmental, Volume 256, 5 November 2019, Article 117845

A system that produces hydrocarbons from carbon dioxide contained in a mixed gas and uses the produced hydrocarbons as fuel uses external energy such as electricity to carbonize carbon dioxide in exhaust gas as fuel. It is regenerated into hydrogen. Therefore, the problem with this system is to reduce the amount of energy supplied from the outside for regeneration and to make the system more efficient.

In the system described in Patent Document 1, carbon dioxide is stored until the carbon dioxide storage component contained in one reactor is saturated, but there is no way to control the supply gas considering the actual use of the system. Not mentioned. Although Non-Patent Documents 1 to 3 describe catalysts housed in reactors, there is no mention of improving the efficiency of the entire system. Further, in none of Patent Documents 2 to 4, high efficiency regarding temperature and heat within the system is studied. As described above, there is room for improvement in increasing efficiency by utilizing heat within the system. In particular, when producing hydrocarbons using carbon dioxide at a low concentration in the atmosphere, the temperature inside the reactor is cooled by the atmosphere. If a catalyst for producing hydrocarbons is also housed in the reactor, it is necessary to heat the reactor, and there is room for improvement in reducing external energy for heating the reactor.

The present invention has been made to solve the above-mentioned problems, and provides a hydrocarbon production system that improves the energy efficiency of the entire system.

The present invention has been made to solve the above-mentioned problems, and can be realized as the following forms.

(1) According to one embodiment of the present invention, a hydrocarbon production system is provided. This hydrocarbon production system includes a carbon dioxide separator that adsorbs and separates carbon dioxide in exhaust gas, and supplies heat obtained from the carbon dioxide separator to the hydrocarbon production equipment via a heat medium. The hydrocarbon production apparatus includes a storage component capable of storing carbon dioxide in the atmosphere, the storage component containing at least one of a metal oxide and a metal hydroxide, and a hydrogen a synthesis catalyst for synthesizing hydrocarbons using hydrogen and carbon dioxide; a first hydrogen supply unit that supplies hydrogen to the first reactor; a flow rate control unit that controls a flow rate of atmospheric air and a flow rate of hydrogen, and the heat exchanger removes heat from the exhaust gas supplied to the carbon dioxide separation device, and removes heat from the exhaust gas supplied to the carbon dioxide separation device. The generated heat is supplied to the first reactor of the hydrocarbon production apparatus.

According to this configuration, heat is removed from the exhaust gas (exhaust gas) supplied to the carbon dioxide separator by the heat medium of the heat exchanger. Carbon dioxide separators have improved carbon dioxide (CO ₂ ) adsorption performance when supplied exhaust gas is at a low temperature. Therefore, the carbon dioxide adsorption performance of the carbon dioxide separator can be improved by lowering the temperature of the exhaust gas due to heat removal. Furthermore, the heat obtained from the exhaust gas by the heat exchanger is used to heat the synthesis catalyst in the first reactor. As a result, when the storage component stores CO ₂ , the synthesis catalyst in the first reactor cooled by the atmosphere can be heated, so that the processing performance of the heated synthesis catalyst is improved. In this way, the use of heat via a heat medium by a heat exchanger improves the overall energy efficiency of the hydrocarbon production system, reducing the external energy required to heat the first reactor to operate the system. Can be reduced.

(2) In the hydrocarbon production system of the above embodiment, the carbon dioxide separation device further includes a reaction catalyst that produces hydrocarbons with heat generation using the carbon dioxide in the exhaust gas and the supplied hydrogen. and a second hydrogen supply section that supplies hydrogen to the second reactor, and the heat exchanger replaces the heat obtained by removing heat from the exhaust gas with: Alternatively, in addition to the heat obtained by removing heat from the exhaust gas, heat generated from the production of hydrocarbons in the second reactor may be supplied to the first reactor.
According to this configuration, the heat exchanger cools the second reactor, which is generating heat during hydrocarbon production in the second reactor. By cooling the second reactor, the hydrocarbon production ability of the reaction catalyst in the second reactor is improved. Furthermore, the heat obtained from the second reactor by the heat exchanger is used to heat the synthesis catalyst in the first reactor. As a result, the overall energy efficiency of the hydrocarbon production system is improved, and external energy for operating the system can be reduced.

(3) In the hydrocarbon production system of the above embodiment, the carbon dioxide separation device further includes an adsorption tower that adsorbs carbon dioxide in the exhaust gas and accommodates a component capable of separating the adsorbed carbon dioxide. , the heat exchanger may supply the heat obtained from the carbon dioxide separation device to the first reactor and further to the adsorption tower.
According to this configuration, the heat obtained from the heat generated during hydrocarbon production in the second reactor is used not only for heating the first reactor but also as the heat necessary for adsorption and separation of _CO2 in the exhaust gas. used. This further improves the overall energy efficiency of the hydrocarbon production system and reduces the external energy required to operate the system.

(4) In the hydrocarbon production system of the above embodiment, the hydrocarbon production apparatus further includes a concentration acquisition unit that acquires the concentration of carbon dioxide contained in the gas discharged from the first reactor, and the The control unit is configured to stop the supply of air to the first reactor when the concentration of carbon dioxide acquired by the concentration acquisition unit is 20 ppm or more and 400 ppm or less, and to stop the supply of air from the first hydrogen supply unit to the first hydrogen supply unit. The supply of hydrogen to one reactor may be started.
According to this configuration, when CO ₂ is stored from the atmosphere to which the storage component is supplied, it is possible to suppress CO ₂ that cannot be stored by the storage component from being discharged to the outside air. As a result, in the system with this configuration, the CO ₂ circulating within the system can be reused with high efficiency.

(5) In the hydrocarbon production system according to the above aspect, the flow rate control section controls the supply of air to the first reactor when the concentration of carbon dioxide obtained by the concentration obtaining section is 20 ppm or more and 150 ppm or less. The process may be stopped, and the supply of hydrogen from the first hydrogen supply section to the first reactor may be started.
According to this configuration, the maximum value of the CO ₂ concentration standard for stopping the supply of air is set even smaller. Therefore, the CO ₂ circulating within the system can be reused with even higher efficiency.

(6) The hydrocarbon production system of the above aspect further includes a heat medium control unit that controls the flow rate of the heat medium through the heat exchanger, and the hydrocarbon production apparatus includes a plurality of the first reactors. The heating medium control unit controls the flow rate of the heating medium for the first reactor to which hydrogen is supplied by the first hydrogen supply unit among the plurality of first reactors. May be supplied.
According to this configuration, while the storage component of one of the first reactors among the plurality of first reactors stores _CO2 , carbon dioxide can be separated from the storage component in another first reactor. As a result, CO ₂ can be reused within the system in a shorter time and with high efficiency without emitting CO ₂ to the outside of the system.

(7) The hydrocarbon production system of the above aspect further includes a heat medium control unit that controls the flow rate of the heat medium through the heat exchanger, and the heat medium control unit controls the flow rate of the heat medium from the heat exchanger to the first reaction. The heating medium may be constantly supplied to the vessel at a controlled flow rate.
According to this configuration, there is no need to provide a valve for opening and closing the heat medium flow path. This simplifies the overall system configuration, increases the processing capacity of the first reactor when desorbing _CO2 from the storage component, and maintains the temperature at which carbon monoxide (CO) is not generated. Can be maintained.

(8) The hydrocarbon production system of the above embodiment may further include a heating section that heats the heat medium.
According to this configuration, when there is little heat obtained from the combustor, the heating section can heat the heat medium supplied to the first reactor. As a result, the temperature of the first reactor when the storage component desorbs CO ₂ can be set to a more appropriate temperature, thereby improving the processing performance of the first reactor.

(9) The hydrocarbon production system of the above aspect further includes a first temperature sensor that detects the temperature of the heating medium, and a heating control section that controls heating of the heating medium by the heating section, and The hydrogen production device further includes a second temperature sensor that detects the temperature of the first reactor, and the heating control unit is configured to control the temperature of the heating medium detected by the first temperature sensor to be lower than the first temperature. In this case, the heating unit heats the heating medium, and when the temperature of the heating medium detected by the first temperature sensor changes from below the first temperature to above the first temperature, the heating stop heating the heat medium by the second temperature sensor, and the flow rate control unit controls the flow rate control unit to stop heating the heat medium by the second temperature sensor, and the flow rate control unit controls the flow rate control unit to The supply of hydrogen from the first hydrogen supply section to the first reactor may be stopped.
According to this configuration, the temperature of the first reactor when desorbing CO ₂ from the storage component is equal to or higher than the first temperature at which the processing performance of the synthesis catalyst is high, and at a temperature at which no CO is generated. The temperature is maintained below the first temperature. As a result, the processing performance of the first reactor when desorbing CO ₂ from the storage component is further improved.

Note that the present invention can be realized in various aspects, such as a hydrocarbon production system, a methane production system, a hydrocarbon production device, a combustion device, a hydrocarbon production method, and a control method for a hydrocarbon production system. It can be realized in the form of a computer program for executing the apparatus or method, a server device for distributing this computer program, a non-temporary storage medium storing the computer program, etc.

1 is a schematic block diagram of a methane production system as an embodiment of the present invention. FIG. 2 is an explanatory diagram of the flow rate of a heat medium supplied to a reactor. It is a flowchart of the methane production method of this embodiment. It is a schematic block diagram of a methane production system of a 2nd embodiment.

<First embodiment>
FIG. 1 is a schematic block diagram of a methane production system (hydrocarbon production system) 300 as an embodiment of the present invention. The methane production system 300 is a system that produces methane, which is a hydrocarbon, from carbon dioxide (CO ₂ ) and burns the produced methane as fuel. As shown in FIG. 1, the methane production system 300 includes a first methane production device (hydrocarbon production device) 100 that produces methane from CO ₂ and hydrogen (H ₂ ), and a first methane production device (hydrocarbon production device) that burns the produced methane as fuel. The second methane production device (carbon dioxide separation device) 200 is supplied with exhaust gas (exhaust gas) containing carbon dioxide generated after combustion by the combustor 1.

The first methane production apparatus 100 includes a reactor (first reactor) 4 containing a catalyst (storage component, synthesis catalyst) 5 that stores CO ₂ and produces methane, and a reactor (first reactor) 4 that stores H ₂ into the reactor 4. A first H ₂ supply section (first hydrogen supply section) 20 to supply, a valve 9 that controls the flow rate of H 2 supplied from the first H ₂ supply section 20 to the reactor 4, and a valve 9 for controlling the flow rate of H ₂ supplied from the first H 2 supply section 20 to the reactor 4. A pump 2 for feeding, a valve 3 for controlling the flow rate of atmospheric air supplied from the pump 2 to the reactor 4, and a CO 2 concentration for detecting the CO ₂ concentration in the exhaust gas (exhaust gas) discharged from the reactor ₄ . A concentration sensor (concentration acquisition unit) 7, a three-way valve 6 that controls the flow rate of the mixed gas discharged from the reactor 4 and supplied to the second methane production device 200, and a heat exchanger 14 to be described later a heating section 12 that heats the heating medium HC supplied to the reactor 4; a first temperature sensor 13 that detects the temperature of the heating medium HC flowing through the heating section 12 and supplied to the reactor 4; Detection of the second temperature sensor 11 that detects the temperature in the reactor 4, the heat medium supply unit 10 that controls the flow rate of the heat medium HC supplied from the heating unit 12 to the reactor 4, and each sensor 7, 11, 13 The control unit 8 includes a control unit 8 that acquires values and controls each of the valves 3, 6, and 9, a heat medium supply unit 10, and a pump 2.

The catalyst 5 housed in the reactor 4 is a mixture of CaO as a storage component capable of storing CO ₂ in the atmosphere and Ru as a synthesis catalyst for synthesizing methane from CO ₂ and H ₂ . In the reactor 4, atmospheric air is supplied by the pump 2, and the storage component stores _CO2 in the atmosphere. Thereafter, the H ₂ supplied from the first H ₂ supply section 20 and the CO ₂ stored in the storage component undergo a methanation reaction as shown in the following formula (1) using a synthesis catalyst, whereby methane is produced. Manufactured.
CO ₂ +4H ₂ → CH ₄ +2H ₂ O...(1)

As shown in FIG. 1, the control unit 8 can discharge the mixed gas discharged from the reactor 4 to the atmosphere by controlling the valve 6. In the CO ₂ storage process in which CO ₂ is stored in the catalyst 5 , the control unit 8 opens the valve 3 and operates the pump 2 to supply atmospheric air to the reactor 4 , closes the valve 9 , and closes the valve 6 . Open and connect to outside air. As a result, the mixed gas containing nitrogen (N ₂ ) and the like after CO ₂ has been stored by the catalyst 5 is released into the atmosphere.

In the CO ₂ storage process, the CO ₂ concentration sensor 7 monitors the state in which the CO ₂ concentration in the exhaust gas from the reactor 4 exceeds 100 ppm. In this embodiment, the CO ₂ concentration sensor 7 transmits a control signal to the control unit 8 when the CO ₂ concentration exceeds 100 ppm. The control unit 8 that has received the control signal stops the CO ₂ storage process and starts the reduction process of supplying H ₂ from the first H ₂ supply unit 20 to the reactor 4 to produce methane from CO ₂ and H ₂ . Start. In the reduction process, the control unit 8 closes the open valve 3, opens the closed valve 9, and connects the outlet of the reactor 4 and the second methane production device 200 by controlling the valve 6. do. When a predetermined period of time has passed after the start of the reduction process, the control unit 8 controls the valves 3, 6, and 9 to switch from the reduction process to the CO ₂ storage process. The control unit 8, pump 2, and valves 3 and 9 in this embodiment correspond to a flow rate control unit. Note that a description of the heat medium HC will be given later.

As shown in FIG. 1, the combustor 1 supplies methane produced by the reactor 4 and methane produced by the methanation reactor 18 of the second methane production device 200, which will be described later, from the atmosphere. Mixes with air and burns. The combusted high-temperature exhaust gas is supplied to the heat exchanger 14.

The second methane production device 200 produces methane, which is a hydrocarbon, by separating and converting CO ₂ in the exhaust gas of the combustor 1. As shown in FIG. 1, the second methane production apparatus 200 includes a second H ₂ supply section (second hydrogen supply section) 21 that supplies H ₂ and H ₂ supplied from the second H ₂ supply section 21 and exhaust gas. A methanation reactor (second reactor) 18 that produces methane as a hydrocarbon through a methanation reaction using CO ₂ in the combustor 1, a dehumidifier 19 that dehumidifies a mixed gas containing methane; a heat exchanger 14 to which exhaust gas from the combustor 1 is supplied and removes heat from the exhaust gas _{; CO2} adsorber (adsorption tower) 17 that supplies CO2 to the methanation reactor 18, and a dehumidifier 15 that removes moisture in the exhaust gas that is supplied from the heat exchanger 14 to the _CO2 adsorber 17. ing.

The methanation reactor 18 accommodates Ru as a reaction catalyst 22 that causes the methanation reaction represented by the above formula (1) using CO ₂ and H ₂ . Therefore, in the methanation reactor 18, methane is produced using H ₂ supplied from the second _{H 2} supply section 21 and CO ₂ supplied from the CO ₂ adsorption device 17. In this embodiment, the reaction catalyst 22 in the methanation reactor 18 and the synthesis catalyst in the reactor 4 are the same catalyst Ru. The heat exchanger 14 removes heat from the high-temperature exhaust gas discharged from the combustor 1, and uses the heat obtained by the heat removal to heat the reactor 4 via the heat medium HC. Note that the heat medium HC in this embodiment is oil, and is configured to flow through the piping.

The exhaust gas whose heat has been removed by the heat exchanger 14 has moisture removed by the dehumidifier 15 and is supplied to the CO ₂ adsorption device 17 . The CO ₂ adsorber 17 contains zeolite as a catalyst that adsorbs CO ₂ in the supplied exhaust gas. After CO ₂ has been adsorbed by the zeolite, the exhaust gas is released into the atmosphere as shown in FIG. Zeolites that have adsorbed CO ₂ separate CO ₂ due to temperature swings. The separated CO ₂ is fed to the methanation reactor 18 .

The circulation of the heat medium HC heated by the heat exchanger 14 between the heat exchanger 14 and the reactor 4 is controlled by the control of the heat medium supply section 10 by the control section 8 . In this embodiment, a double pipe structure is adopted in which the heat medium HC can flow around the reactor 4, so the heat generated by the combustor 1 is supplied to the reactor 4 via the heat medium HC. be done. Note that in other embodiments, the heat exchanger 14 may include a mass flow controller to more precisely control the flow rate of the heat medium HC. The control section 8 and the heat medium supply section 10 correspond to a heat medium control section.

In this embodiment, the control unit 8 does not circulate the heat medium HC in the CO ₂ storage process of the reactor 4, but circulates the heat medium HC in the reduction process. The control unit 8 constantly acquires the temperature detected by the first temperature sensor 13 and the temperature detected by the second temperature sensor 11. The control unit 8 controls the heat medium supply unit 10 according to the two acquired detected temperatures. Specifically, when the process of the reactor 4 is switched from the CO ₂ storage process to the reduction process, the control unit 8 controls the heat medium supply unit 10 to circulate the heat medium HC. The control unit 8 controls the heating unit 12 to heat the heating medium HC when the temperature of the heating medium HC in the heating unit 12 detected by the first temperature sensor 13 is less than 250° C. (first temperature). . The control unit 8 stops heating the heat medium HC when the temperature of the heat medium HC in the heating unit 12 changes to 250° C. or higher. On the other hand, if the temperature of the heating medium HC in the heating unit 12 when switching to the reduction process exceeds 330°C (second temperature T2), which is higher than 250°C, the control unit 8 controls the heating medium HC. stop the circulation. This is because if the temperature inside the reactor 4 is too high, there is a risk that carbon monoxide (CO) will be produced by the catalyst 5 and that the reaction activity will decrease. Note that the control section 8 corresponds to a heating control section.

FIG. 2 is an explanatory diagram of the flow rate of the heat medium HC supplied to the reactor 4. FIG. 2 shows a flow rate map of the heat medium HC determined by the control unit 8 of the present embodiment in accordance with the temperature of the reactor 4 and the amount of H ₂ supplied to the reactor 4 in the reduction process. It is shown. As shown in FIG. 2, the control unit 8 takes the supply amount of H ₂ to the reactor 4 as the horizontal axis, and calculates the temperature of the reactor 4 detected by the second temperature sensor 11 from 330° C. as a threshold value. The flow rate of the heat medium HC to be supplied to the reactor 4 is determined from the map in which the vertical axis is the subtracted value. The solid lines shown in FIG. 2 represent that the flow rates of the heat medium HC are the same. That is, as shown by the broken line arrow in FIG. 2, the control unit 8 increases the flow rate of the heat medium HC supplied to the reactor 4 as the amount of H ₂ supplied is large and the temperature difference is large. . On the other hand, the control unit 8 decreases the flow rate of the heat medium HC supplied to the reactor 4 as the supply amount of H ₂ decreases and the temperature difference decreases.

FIG. 3 is a flowchart of the methane production method of this embodiment. In the manufacturing flow shown in FIG. 3, first, a CO ₂ storage step is started in which CO ₂ is stored in the catalyst 5 housed in the reactor 4 (step S1). At the start of the CO ₂ storage process, the control unit 8 supplies atmospheric air into the reactor 4 by operating the pump 2 with the valves 3 and 6 open and the valve 9 closed. Atmospheric air containing CO ₂ is discharged from the reactor 4 and discharged through the valve 6 .

The CO ₂ concentration sensor 7 constantly detects the CO ₂ concentration in the exhaust gas discharged to the outside air via the valve 6 (step S2). The control unit 8 determines whether the CO ₂ concentration detected by the CO ₂ concentration sensor 7 exceeds 100 ppm (step S3). When the control unit 8 determines that the CO ₂ concentration is 100 ppm or less (step S3: NO), the control unit 8 continues to monitor the CO ₂ concentration.

On the other hand, if the control unit 8 determines that the CO ₂ concentration exceeds 100 ppm (step S3: YES), it stops the CO ₂ storage process and changes the process performed in the reactor 4 to a reduction process. switching (step S4). When switching to the reduction process, the control unit 8 closes the open valve 3 to stop the operation of the pump 2, opens the valve 9 to supply H ₂ to the reactor 4, and switches the valve 6 to the second methane production stage. Connect to device 200. Moreover, the control unit 8 starts circulating the heat medium HC to the reactor 4 by controlling the heat medium supply unit 10 (step S5).

The control unit 8 determines whether the temperature of the heat medium HC in the heating unit 12 acquired by the first temperature sensor 13 is lower than the first temperature T1 (250° C.) (step S6). If it is determined that the temperature of the heat medium HC in the heating section 12 is equal to or higher than the first temperature T1 (step S6: NO), the process of step S10, which will be described later, is performed. On the other hand, if the control unit 8 determines that the temperature of the heat medium HC in the heating unit 12 is lower than the first temperature T1 (step S6: YES), the control unit 8 operates the heating unit 12 to reduce the temperature of the heat medium HC. is heated (step S7).

Next, the control unit 8 determines whether the temperature of the heated heating medium HC detected by the first temperature sensor 13 exceeds 250° C. (step S8). When the control unit 8 determines that the temperature of the heat medium HC does not exceed the first temperature T1 (step S8: NO), the heating unit 12 continues to heat the heat medium HC. On the other hand, when the control unit 8 determines that the temperature of the heat medium HC exceeds the first temperature T1 (step S8: YES), the control unit 8 stops the heating of the heat medium HC by the heating unit 12 (step S9). , the process of step S10 is performed.

In the process of step S10, the control unit 8 determines whether the temperature of the reactor 4 detected by the second temperature sensor 11 is higher than the second temperature T2 (330° C.) (step S10). If it is determined that the temperature of the reactor 4 exceeds 330° C. (step S10: YES), the control unit 8 stops the circulation of the heat medium HC (step S11), and performs the process of step S12. On the other hand, when the control unit 8 determines that the temperature of the heat medium HC in the reactor 4 is equal to or lower than the second temperature T2 (step S10: NO), the control unit 8 determines that the temperature of the heat medium HC in the reactor 4 is lower than or equal to the second temperature T2 (step S10: NO). It is determined whether the time has elapsed (step S12).

If it is determined that the predetermined time has not elapsed since switching to the reduction process (step S12: NO), the processes from step S6 onwards are repeated. On the other hand, if the control unit 8 determines that the predetermined time has elapsed since switching to the reduction process (step S12: YES), the control unit 8 controls the heating medium supply unit 10 to supply the heating medium. The circulation of HC is stopped, the valves 6 and 9 are closed, and the reduction process is stopped (step S13). After that, the control unit 8 determines the end of methane production by accepting a predetermined operation or the like (step S14). When the control unit 8 determines that methane production is not to be ended (step S14: NO), the control unit 8 repeats the processing from step S1 onwards. On the other hand, if the control unit 8 receives the predetermined operation, it determines to end the methane production (step S14: YES), and the methane production flow ends.

As explained above, the methane production system 300 of this embodiment includes the first methane production device 100, the second methane production device 200 to which exhaust gas containing CO ₂ is supplied from the combustor 1, and the heat exchanger 14. It is equipped with The first methane production apparatus 100 includes a reactor 4 containing a CO ₂ storage component and a synthesis catalyst that causes a methanation reaction, a first H ₂ supply section 20 that supplies H ₂ to the reactor 4, and a reaction The control unit 8 controls the flow rate of H ₂ and atmospheric air supplied to the vessel 4. The combustion device 200 includes a CO ₂ adsorption device 17 that separates CO ₂ from the exhaust gas of the combustor 1 . The heat exchanger 14 removes heat from the high-temperature exhaust gas supplied to the second methane production apparatus 200 using the heat medium HC, and uses the heat obtained by the heat removal to heat the reactor 4. Therefore, in this embodiment, the high temperature exhaust gas discharged from the combustor 1 is cooled by the heat medium HC of the heat exchanger 14. The CO ₂ adsorption device 17 has improved CO ₂ adsorption performance when the supplied exhaust gas is at a low temperature. Therefore, the CO ₂ adsorption performance in the second methane production apparatus 200 can be improved by lowering the temperature of the exhaust gas due to heat removal. Furthermore, the heat obtained from the exhaust gas by the heat exchanger 14 is used to heat the reactor 4 undergoing the reduction process. As a result, the synthesis catalyst in the reactor 4 that was cooled by the atmosphere during the CO ₂ storage process can be heated, so that the processing performance of the reactor 4 during the reduction process is improved. In this way, by utilizing heat via the heat medium HC by the heat exchanger 14, the overall energy efficiency of the methane production system 300 is improved, and external energy for heating the catalyst 5 in the reactor 4 can be reduced.

Further, the first methane production apparatus 100 of this embodiment includes a CO _{2 concentration sensor 7 that detects the CO 2 concentration} in the exhaust gas of the reactor 4. When the CO ₂ storage process is performed in the reactor 4 and the CO ₂ concentration detected by the CO ₂ concentration sensor 7 becomes higher than 100 ppm, the control unit 8 switches from the CO ₂ storage process to the reduction process. Therefore, in the reactor 4 of this embodiment, when the CO ₂ storage process is performed, it is possible to suppress a large amount of CO ₂ from being discharged to the outside air. As a result, in the methane production system 300, CO ₂ circulating within the system can be reused with high efficiency.

Further, the first methane production apparatus 100 of this embodiment includes a heating section 12 that heats the temperature of the heat medium HC supplied from the heat exchanger 14 to the reactor 4. Therefore, in this embodiment, when there is little heat obtained from the combustor 1, the heating medium HC supplied to the reactor 4 can be heated by the heating section 12. As a result, the temperature of the reactor 4 during the reduction process can be set to a more appropriate temperature, so that the processing performance of the reactor 4 is improved.

Further, the first methane production apparatus 100 of the present embodiment includes a first temperature sensor 13 that detects the temperature of the heat medium HC in the heating section 12, a second temperature sensor 11 that detects the temperature in the reactor 4, It is equipped with As shown in FIG. 3, the control unit 8 causes the heating unit 12 to heat the heating medium HC when the temperature of the heating medium HC detected by the first temperature sensor 13 is lower than the first temperature T1 (250° C.). let Further, the control unit 8 stops the circulation of the heat medium HC when the temperature of the reactor 4 detected by the second temperature sensor 11 exceeds the second temperature T2 (330° C.). Therefore, the temperature of the reactor 4 in which the reduction process is performed is maintained at a temperature at which the processing performance of the synthesis catalyst is high and no CO is generated. As a result, the processing performance of the reactor 4 during the reduction process is further improved.

<Modified example of the first embodiment>
In the first embodiment, as shown in FIG. 3, the heat medium HC is supplied to the reactor 4 during the reduction process, and the heat medium HC is supplied to the reactor 4 during the CO ₂ storage process. Not yet. In contrast, the control unit 8 of the modified example constantly supplies heat medium HC with a controlled flow rate from the heat exchanger 14 to the reactor 4. In this case, the control unit 8 constantly monitors the temperatures detected by the first temperature sensor 13 and the second temperature sensor 11, and uses the same thresholds of 250°C and 330°C as in the first embodiment to and process switching.

As explained above, in this modification, the heating medium HC is constantly circulating between the heat exchanger 14 and the reactor 4, so the system is equipped with a valve for opening and closing the flow path of the heating medium HC. It doesn't have to be. This makes it possible to simplify the overall system configuration, increase the throughput of the reactor 4 in the reduction process, and maintain the temperature at which CO is not generated.

The methane production apparatus 100 has a plurality of reactors 4, and the control unit 8 supplies heat medium HC to the reactor 4, which is supplied with _H2 by the first _H2 supply unit 20, among the plurality of reactors 4. You may. Thereby, while performing the CO ₂ storage step in one of the reactors 4, it is possible to perform the reduction step in another reactor 4. As a result, CO ₂ can be reused in a shorter time and with high efficiency without emitting CO ₂ to the outside.

<Second embodiment>
FIG. 4 is a schematic block diagram of a methane production system 300a according to the second embodiment. In the methane production system 300a of the second embodiment, compared to the methane production system 300 of the first embodiment, the heat exchanger 14a included in the second methane production device 200a and the control unit 8a included in the first methane production device 100a are However, other configurations and the like are the same as in the first embodiment. Therefore, in the second embodiment, configurations and the like that are different from the first embodiment will be explained, and other explanations will be omitted.

The heat exchanger 14a of the second embodiment replaces the heat obtained by removing heat from the exhaust gas of the combustor 1 with the heat obtained by the exothermic reaction of the methanation reaction in the methanation reactor 18, using the heat medium HC. It is supplied to both the reactor 4 and the CO ₂ adsorber 17 via the CO 2 adsorber 17 . Note that, like the reactor 4, the CO ₂ adsorption device 17a of the second embodiment has a double pipe structure.

As explained above, in the methane production system 300a of the second embodiment, the second methane production device 200a includes the second H ₂ supply section 21 that supplies H ₂ to the methanation reactor 18, and the CO ₂ in the exhaust gas. and a methanation reactor 18 that produces methane through a methanation reaction using H ₂ from the second H ₂ supply section 21 . The heat exchanger 14a supplies heat obtained by the heat generated by the methanation reaction to the reactor 4 instead of the heat obtained by removing heat from the exhaust gas of the combustor 1. Therefore, in the methane production system 300a of the second embodiment, the methanation reactor 18 in which the methanation reaction is occurring is cooled by the heat exchanger 14. Since the methanation reaction is an exothermic reaction, the methane production capacity is improved by cooling. Furthermore, the heat obtained from the methanation reactor 18 by the heat exchanger 14 is used to heat the reactor 4 undergoing the reduction process. As a result, the overall energy efficiency of the methane production system 300a is improved, and external energy for operating the system can be reduced.

Further, the CO ₂ adsorber 17a included in the second methane production apparatus 200a of the second embodiment contains zeolite that can adsorb CO ₂ in exhaust gas and separate the adsorbed CO ₂ by temperature swing. The heat exchanger 14a also utilizes the heat obtained from the methanation reactor 18 for temperature swings to separate _CO2 from the zeolite. Therefore, in the methane production system 300a of the second embodiment, the heat obtained by the exothermic reaction of the methanation reaction is used not only for heating the reactor 4 but also as the heat necessary for adsorption and separation of _CO2 in the exhaust gas. used. This further improves the overall energy efficiency of the methane production system 300a, and reduces the external energy needed to operate the system.

<Modified example of second embodiment>
The heat exchanger 14a supplies the heat generated by the methanation reaction to the reactor 4 and the CO ₂ adsorber 17a instead of the heat obtained by removing heat from the exhaust gas of the combustor 1. The heat obtained by both the heat removal of the exhaust gas and the heat generated by the methanation reaction may be supplied to at least one of the reactor 4 and the CO ₂ adsorption device 17a.

<Modification of the above embodiment>
The present invention is not limited to the above-described embodiments, and can be implemented in various forms without departing from the spirit thereof. For example, the following modifications are also possible.

[Modification 1]
The methane production systems 300, 300a of the first embodiment and the second embodiment are merely examples, and the configuration and control executed by the methane production systems 300, 300a can be modified in various ways. For example, the heat exchangers 14, 14a for circulating the heat medium HC, the heating section 12, the first temperature sensor 13, and the heat medium supply section 10 are connected to the first methane production apparatus 100, 100a and the second methane production apparatus 200. , 200a, and may be provided in the methane production systems 300, 300a as an independent configuration. The methane production system 300 includes a first methane production device 100, a second methane production device 200 capable of attaching and detaching carbon dioxide, and a heat exchanger 14. , the first H ₂ supply section 20, and the flow rate control section. Therefore, the first methane production apparatus 100, 100a does not need to include the heating unit 12 and the CO ₂ concentration sensor 7, and may include other configurations. Further, the second methane production apparatus 200, 200a may not include the second H ₂ supply section 21 and the methanation reactor 18, and may include other configurations. For example, the pump 2 can be modified as long as it is a device that has the function of sending atmospheric air into the reactor 4, and may be a blower fan or the like. The heat exchanger 14, 14a may be an integrated device with a dehumidifier 15.

Although methane has been described as an example of the hydrocarbon produced by the first methane production apparatus 100, 100a and the second methane production apparatus 200, 200a, the hydrocarbon produced may be other than methane, for example. , ethane or propane. The synthesis catalyst and reaction catalyst 22 to be accommodated in the reactor 4 and the methanation reactor 18 may be selected depending on the hydrocarbon to be produced. Furthermore, the control temperatures of the reactor 4 and the methanation reactor 18 may be appropriately selected depending on the synthesis catalyst, reaction catalyst 22, etc. to be accommodated. Although the storage component accommodated in the reactor 4 of the first embodiment was CaO, at least one of metal oxides and metal hydroxides capable of storing CO ₂ in the atmosphere may be selected. , for example, may be Na, Ca, or a combination thereof. Further, in the first embodiment, Ru is used as an example of the synthesis catalyst or reaction catalyst 22 that causes the methanation reaction in the reactor 4 and the methanation reactor 18, but it may be other than Ru, for example. , Ni, etc.

Although the first temperature sensor 13 of the first embodiment is disposed within the heating section 12, it can be modified within a range capable of detecting the temperature of the heating medium HC supplied to the reactor 4. For example, it may be arranged in the heat medium supply section 10 or in a pipe connecting the heat medium supply section 10 and the heating section 12. Similarly, the second temperature sensor 11 can be modified within a range that can detect the temperature of the reactor 4, and may detect the temperature at the outlet of the heat medium discharged from the reactor 4, for example.

Although the control units 8 and 8a controlled each part of the first methane production apparatuses 100 and 100a and the second methane production apparatuses 200 and 200a, they may be separated for each control function. For example, a control unit that controls the heat medium supply unit 10, a control unit that controls the heating unit 12, a control unit that controls the flow rate of the atmosphere supplied to the reactor 4, a first H 2 supply unit 20 and a second H ₂ supply unit 20, The control unit that controls the 2H ₂ supply unit 21 may be configured independently. The first H ₂ supply section 20 and the second H ₂ supply section 21 are formed by one hydrogen tank, and are supplied to the reactor 4 and the methanation reactor 18 through branched piping and control sections 8 and 8a. The flow rate of _H2 may be controlled.

In the first and second embodiments described above, a part of the configuration that is realized by hardware may be replaced with software, or conversely, a part of the configuration that is realized by software may be replaced by hardware. It may be replaced with clothing.

[Modification 2]
As shown in step S3 in FIG. 3, the control unit 8 of the first embodiment compares the CO ₂ concentration in the exhaust gas of the reactor 4 detected by the CO ₂ concentration sensor 7 with 100 ppm as a threshold value. Although the switching from the CO ₂ storage process to the reduction process was determined based on the above, the switching determination can be modified. For example, the control unit 8 may switch from the CO ₂ storage process to the reduction process by determining the elapse of a preset threshold time. Further, when determining switching based on the CO ₂ concentration, the control unit 8 preferably uses a threshold value of 20 ppm or more and 400 ppm or less. Furthermore, it is more preferable that the control unit 8 adopts a threshold value of 20 ppm or more and 150 ppm or less. By reducing the maximum value of the threshold value, the CO ₂ circulating within the methane production system 300 can be reused with even higher efficiency.

As shown in steps S6 and S8 of FIG. 3, the control unit 8 of the first embodiment compares the temperature detected by the first temperature sensor 13 with the first temperature T1, which is 250° C., as a threshold value. Although the operation of the heating section 12 is controlled, the operation determination of the heating section 12 can be modified. For example, the operation of the heating unit 12 may be turned on or off depending on the time that has passed since the reduction process was performed. The heating unit 12 may be a well-known device, such as a heater operated by electric power. Furthermore, the first temperature T1 may vary depending on the position where the first temperature sensor 13 is placed in the methane production system 300, or may vary depending on the type of hydrocarbon to be produced or the amount of hydrocarbon accommodated in the reactor 4. It may be changed depending on the catalyst 5. Similarly, as shown in step S10 in FIG. 3, the control unit 8 performs the reduction process when the detected temperature of the second temperature sensor 11 exceeds 330° C., which is the second temperature T2 as a threshold value. Although the reduction process was stopped, various modifications can be made to the determination of whether to stop the reduction process. The second temperature T2 is higher than the first temperature T1, and may vary depending on the position where the second temperature sensor 11 is placed and the size of the reactor 4. For example, the methane production system 300 includes a cooling unit that cools the heat medium HC, and the control unit 8 may start cooling the heat medium HC instead of ending the reduction process.

In the flowchart of the methane production method shown in FIG. 3, for convenience of explanation, the end of the flow is determined at the end of the reduction step, but the timing of the start and end of the flow can be modified as appropriate. For example, the determination of the end of the flow may be made in the middle of the CO ₂ storage step, or may be made in the middle of the CO ₂ storage step or the reduction step.

Although the present aspect has been described above based on the embodiments and modified examples, the embodiments of the above-described aspect are for facilitating understanding of the present aspect, and do not limit the present aspect. This aspect may be modified and improved without departing from the spirit and scope of the claims, and this aspect includes equivalents thereof. Furthermore, if the technical feature is not described as essential in this specification, it can be deleted as appropriate.

1...Combustor 2...Pump (flow rate control section)
3, 9...Valve (flow control section)
4...Reactor (first reactor)
5...Catalyst (storage catalyst, synthesis catalyst)
6... Valve 7... CO ₂ concentration sensor (concentration acquisition section)
8, 8a...Control unit (flow rate control unit, heating medium control unit, heating control unit)
10...Heat medium supply section (heat medium control section)
11... Second temperature sensor 12... Heating section 13... First temperature sensor 14, 14a... Heat exchanger 15, 19... Dehumidifier 17, 17a... CO ₂ adsorption device (adsorption tower)
18...Methanation reactor (second reactor)
20...First H ₂ supply section (first hydrogen supply section)
21...Second H ₂ supply section (second hydrogen supply section)
22...Reaction catalyst 100,100a...First methane production device (hydrocarbon production device)
200, 200a...Second methane production device (carbon dioxide separation device)
300, 300a...Methane production system (hydrocarbon production system)
HC...Heat medium T1...First temperature T2...Second temperature

Claims (9)

A hydrocarbon production system,
A hydrocarbon production device that produces hydrocarbons from hydrogen and carbon dioxide in the atmosphere;
a carbon dioxide separator that adsorbs and separates carbon dioxide in exhaust gas;
a heat exchanger that supplies the heat obtained from the carbon dioxide separation device to the hydrocarbon production device via a heat medium;
Equipped with
The hydrocarbon production device includes:
A storage component capable of storing carbon dioxide in the atmosphere and containing at least one of a metal oxide and a metal hydroxide, and a synthesis catalyst that synthesizes hydrocarbons using hydrogen and carbon dioxide; a first reactor containing;
a first hydrogen supply section that supplies hydrogen to the first reactor;
a flow rate control unit that controls the flow rate of the atmosphere and the flow rate of hydrogen supplied to the first reactor;
has
The heat exchanger removes heat from the exhaust gas supplied to the carbon dioxide separation device, and supplies the heat obtained by the heat removal to the first reactor of the hydrocarbon production device. . The hydrocarbon production system according to claim 1,
The carbon dioxide separator further includes:
a second reactor containing a reaction catalyst that produces hydrocarbons with heat generation using carbon dioxide in the exhaust gas and supplied hydrogen;
a second hydrogen supply section that supplies hydrogen to the second reactor;
has
The heat exchanger uses heat generated from the production of hydrocarbons in the second reactor in place of the heat obtained by removing heat from the exhaust gas, or in addition to the heat obtained by removing heat from the exhaust gas. A hydrocarbon production system that supplies a hydrocarbon to the first reactor. The hydrocarbon production system according to claim 1 or 2,
The carbon dioxide separation device further includes an adsorption tower that adsorbs carbon dioxide in the exhaust gas and accommodates a component that can separate the adsorbed carbon dioxide,
In the hydrocarbon production system, the heat exchanger supplies the heat obtained from the carbon dioxide separation device to the first reactor and further to the adsorption tower. The hydrocarbon production system according to any one of claims 1 to 3,
The hydrocarbon production apparatus further includes a concentration acquisition unit that acquires the concentration of carbon dioxide contained in the gas discharged from the first reactor,
The flow rate control unit is configured to stop the supply of air to the first reactor when the concentration of carbon dioxide acquired by the concentration acquisition unit is 20 ppm or more and 400 ppm or less, and to stop supplying air from the first hydrogen supply unit. A hydrocarbon production system that starts supplying hydrogen to the first reactor. The hydrocarbon production system according to claim 4,
The flow rate control unit stops the supply of air to the first reactor when the concentration of carbon dioxide acquired by the concentration acquisition unit is 20 ppm or more and 150 ppm or less, and stops supplying air from the first hydrogen supply unit. A hydrocarbon production system that starts supplying hydrogen to the first reactor. The hydrocarbon production system according to any one of claims 1 to 5, further comprising:
comprising a heat medium control unit that controls the flow rate of the heat medium by the heat exchanger,
The hydrocarbon production apparatus includes a plurality of the first reactors,
The heating medium control unit controls the flow rate of the heating medium and supplies it to the first reactor to which hydrogen is supplied by the first hydrogen supply unit among the plurality of first reactors. , hydrocarbon production systems. The hydrocarbon production system according to any one of claims 1 to 5, further comprising:
comprising a heat medium control unit that controls the flow rate of the heat medium by the heat exchanger,
In the hydrocarbon production system, the heat medium control unit always supplies the heat medium with a controlled flow rate from the heat exchanger to the first reactor. The hydrocarbon production system according to any one of claims 1 to 7, further comprising:
A hydrocarbon production system including a heating section that heats the heat medium. The hydrocarbon production system according to claim 8, further comprising:
a first temperature sensor that detects the temperature of the heating medium;
a heating control unit that controls heating of the heating medium by the heating unit;
Equipped with
The hydrocarbon production apparatus further includes a second temperature sensor that detects the temperature of the first reactor,
The heating control section includes:
heating the heating medium by the heating unit when the temperature of the heating medium detected by the first temperature sensor is less than a first temperature;
When the temperature of the heat medium detected by the first temperature sensor changes from below the first temperature to above the first temperature, stopping heating of the heat medium by the heating unit,
The flow rate control unit is configured to control the flow rate from the first hydrogen supply unit to the first reactor when the temperature of the first reactor detected by the second temperature sensor exceeds a second temperature higher than the first temperature. A hydrocarbon production system that stops supplying hydrogen to.

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