Gas production system and method for operating the gas production system

Abstract

The gas production system (100) includes switching units (21, 22) that adjust opening and closing of flow paths (L1, L4), and a hollow reaction unit (40A) that is connected to the flow paths (L1, L4) and has a reducing agent therein. The reaction unit (40A) is connected via the flow paths (L1, L4) to a first supply unit (11) that supplies a first A gas (G1A) containing carbon dioxide and oxygen, and a second supply unit (13) that supplies a reducing gas. 2) enables switching between contact between the first A gas (G1A) supplied from the first supply unit (11) and the first reducing agent, which is a reducing agent containing a metal oxide; contact between the second reducing agent, which is the first reducing agent in contact with the first A gas, and the reducing gas (G3); and contact between the third reducing agent, which is the second reducing agent in contact with the reducing gas (G3), and the first B gas (G1B), which is the first A gas (G1A) in contact with the first reducing agent.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to gas production systems and methods of operating gas production systems. [Background technology]

[0002] In recent years, research and development has been progressing on technologies for capturing carbon dioxide (CO2) from exhaust gases, the atmosphere, etc., and converting the captured CO2 into valuable substances, with the aim of preventing global warming and realizing a carbon-recycling society. For example, a CO2-containing feed gas is brought into contact with a reducing agent containing a metal oxide that reduces CO2 to produce a product gas containing carbon monoxide (CO). In order to improve the production efficiency of the product gas, it is important to increase the CO2 concentration in the feed gas. Therefore, the following gas production apparatus has been disclosed, which is configured to remove unnecessary gas components, mainly O2, contained in the feed gas.

[0003] That is, conventional gas production apparatuses are equipped with a concentration adjustment unit having an oxygen removal device, such as a low-temperature separation separator, a pressure swing adsorption separator, or a temperature swing adsorption separator, for removing oxygen from a raw material gas. The raw material gas, which has passed through this concentration adjustment unit and from which oxygen has been removed, is brought into contact with a reducing agent containing a metal oxide in a reactor to produce a product gas containing carbon monoxide (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-75447 Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional gas production system, an oxygen removal device such as a low-temperature separation separator is installed upstream of the reactor to remove unnecessary gas components, mainly oxygen (O2), contained in the raw gas. However, such oxygen removal devices are relatively expensive and consume a lot of power. Therefore, the conventional gas production system has a problem in that the energy lost when driving the oxygen removal device results in a decrease in gas production efficiency.

[0006] The present disclosure discloses a technique for solving the above-mentioned problems, and aims to provide a gas production system and an operating method for a gas production system that are inexpensive and have high gas production efficiency. [Means for solving the problem]

[0007] The gas production system of the present disclosure includes: a switching unit provided in the flow path and configured to adjust opening and closing of the flow path; connected to the flow path, Contains metals that reduce carbon dioxide and are reduced by hydrogen a hollow reaction section having a reducing agent therein; The reaction section is a first supply unit that supplies a first A gas containing carbon dioxide and oxygen; Contains hydrogen a second supply unit that supplies a reducing gas, and the second supply unit is connected to the second supply unit via the flow path; By adjusting the opening and closing of the flow path by the switching unit, in the reaction unit, a contact between the first A gas supplied from the first supply unit and a first reducing agent as the reducing agent containing a metal oxide; a contact between a second reducing agent as the first reducing agent in contact with the first A gas and the reducing gas; and a contact between a third reducing agent as the second reducing agent in contact with the reducing gas and a first B gas as the first A gas in contact with the first reducing agent. It is something. Further, the method for operating a gas production system according to the present disclosure includes: an oxygen reaction step of contacting a first A gas containing carbon dioxide and oxygen with a first reducing agent containing a metal oxide to produce a first B gas from which the oxygen in the first A gas has been removed; a hydrogen reaction step in which a second reducing agent, which is the first reducing agent oxidized by the oxygen in the first A gas, is brought into contact with a reducing gas containing hydrogen to generate a third reducing agent by reducing the second reducing agent; a carbon dioxide reaction step in which the third reducing agent is brought into contact with the first B gas to reduce the carbon dioxide in the first B gas and generate a product gas containing carbon monoxide, and the third reducing agent is oxidized to generate the first reducing agent to be used in the oxygen reaction step. It is something. [Effects of the Invention]

[0008] According to the gas production system and the method for operating the gas production system of the present disclosure, an inexpensive gas production system and a method for operating the gas production system with high gas production efficiency can be obtained. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram showing a schematic configuration of a gas production system according to a first embodiment. [Figure 2] 3 is a flowchart showing a method for operating the gas production system according to the first embodiment. [Figure 3] FIG. 3 is a block diagram showing another schematic configuration of the gas production system according to the first embodiment. [Figure 4] 2 is a diagram showing a hardware configuration of a control unit of the gas production system according to the first embodiment. FIG. [Figure 5] FIG. 10 is a block diagram showing a schematic configuration of a gas production system according to a second embodiment. [Figure 6] FIG. 10 is a diagram for explaining the reaction state of each switching reactor in the first step in the gas production system according to the second embodiment. [Figure 7] FIG. 10 is a diagram for explaining the reaction state of each switching reactor in the second step in the gas production system according to the second embodiment. [Figure 8]FIG. 10 is a diagram for explaining the reaction state of each switching reactor in the third step in the gas production system according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Embodiment 1 FIG. 1 is a block diagram showing a schematic configuration of a gas production system 100 according to the first embodiment. The gas production system 100 of this embodiment converts a raw material gas such as an exhaust gas containing carbon dioxide CO2 and oxygen O2 into a product gas that is a valuable substance containing carbon monoxide CO using a reducing agent.

[0011] As shown in FIG. 1, the gas production system 100 includes a first reactor 41 as a first reaction section, a second reactor 42 as a second reaction section, and a third reactor 43 as a third reaction section, each of which is a hollow reaction section containing a reducing agent inside. In the following description, when there is no need to distinguish between the first reactor 41, the second reactor 42, and the third reactor 43, they may be simply referred to as reactors.

[0012] In addition, the reaction section of this gas production system 100 is connected to a raw material gas supply section 11 as a first supply section that supplies raw material gas G1A as gas 1A, a hydrogen generator 13 as a second supply section that generates a gas containing hydrogen that is reducing gas G3, a generated gas discharge section 12 that discharges generated gas G2, and a water vapor discharge device 14 that discharges water vapor G4.

[0013] Specifically, the raw material gas supply unit 11 and the first reactor 41 are connected by a raw material gas pipe L1, which serves as a flow path for supplying the raw material gas G1A to the first reactor 41. The first reactor 41 and the second reactor 42 are connected by an oxygen removal pipe L2 as a flow path. The produced gas discharge section 12 and the second reactor 42 are connected by a produced gas pipe L3, which serves as a flow path for discharging the produced gas G2. The hydrogen generator 13 and the third reactor 43 are connected by a reducing gas pipe L4 serving as a flow path for supplying the reducing gas G3 to the third reactor 43. The water vapor discharge device 14 and the third reactor 43 are connected by a water vapor discharge pipe L5 which serves as a flow path for discharging water vapor.

[0014] Furthermore, the gas production system 100 includes circulation piping that circulates the reducing agent between the reactors. Specifically, the gas production system 100 includes a circulation piping L6A as a first transfer unit that transfers the reducing agent from the first reactor 41 to the third reactor 43, a circulation piping L6B as a second transfer unit that transfers the reducing agent from the third reactor 43 to the second reactor 42, and a circulation piping L6C as a third transfer unit that transfers the reducing agent from the second reactor 42 to the first reactor 41. With this configuration, the reducing agent can flow through the first reactor 41, the third reactor 43, the second reactor 42, and the first reactor 41 in this order.

[0015] Furthermore, the gas production system 100 is provided with regulating valves as switching units that control the opening and closing of each pipe at the upstream and downstream stages of each reactor. Specifically, a regulating valve 21 serving as a first switching unit is provided between the raw material gas supply unit 11 and the first reactor 41. In addition, a regulating valve 22 serving as a second switching unit is provided between the hydrogen generation device 13 and the third reactor 43.

[0016] In addition, an adjustment valve 23 is provided in the oxygen removal pipe L2 between the first reactor 41 and the second reactor 42. In addition, an adjustment valve 24 is provided in the produced gas pipe L3 between the second reactor 42 and the produced gas discharge section 12. In addition, an adjustment valve 25 is provided in the water vapor discharge pipe L5 between the third reactor 43 and the water vapor discharge device 14. The circulation pipe L6A is provided with regulating valves 31 and 32. The circulation pipe L6B is provided with regulating valves 33 and 34. The circulation pipe L6C is provided with regulating valves 35 and 36. Although two adjustment valves 31 and 32 are provided in the circulation pipe L6A, only one of them may be provided. Furthermore, although two adjustment valves 33 and 34 are provided in the circulation pipe L6B, only one of them may be provided. Furthermore, although two adjustment valves 35 and 36 are provided in the circulation pipe L6C, only one of them may be provided.

[0017] In the following description, when there is no need to distinguish between the regulating valves 21 to 25 and 31 to 36, they may be simply referred to as regulating valves. Furthermore, the gas production system 100 includes a control unit 50 that can control the open / closed state of each of these regulating valves, and controls each regulating valve according to each mode, which will be described later.

[0018] Furthermore, the raw material gas supply unit 11 is provided with a blower (not shown) that pressure-feeds the raw material gas G1A. Furthermore, the raw material gas pipe L1 is provided with a heater 1 that heats the raw material gas G1A. Furthermore, the oxygen removal pipe L2 is provided with a heater 2 that heats the gas supplied from the first reactor 41. Furthermore, the reducing gas pipe L4 is provided with a heater 3 that heats the reducing gas G3.

[0019] The reducing agent is a material that can be oxidized by carbon dioxide and reduced by hydrogen. For example, at least one metal element from Groups 3 to 12 can be selected as such a material. Iron-containing metal oxides and composite oxides are particularly preferred because they have a particularly high conversion efficiency of carbon dioxide (CO2) to carbon monoxide (CO).

[0020] The reducing agent is preferably in the form of granules, flakes, or pellets. The reducing agent in such a shape can increase the filling rate inside each reactor, thereby increasing the contact efficiency between the reducing agent and the gas. The reducing agent may also be supported on a carrier.

[0021] Each reactor is maintained at a temperature suitable for the oxidation reaction of the reducing agent with carbon dioxide and the reduction reaction of the oxidized reducing agent with hydrogen. The temperature of each reactor is set, for example, depending on the material of the reducing agent, and is preferably 600 to 1000°C for metal oxides and composite oxides containing iron. The higher the temperature of each reactor, the faster the reaction rate, and therefore the larger the gas throughput.

[0022] On the other hand, the lower the temperature of each reactor, the less thermal energy is required to raise the temperature, and the lower the heat resistance required for the components of each reactor, which makes it possible to reduce the manufacturing costs, running costs, etc. of the gas production system. Furthermore, the temperature of each reactor may or may not be different for the oxidation reaction and the reduction reaction. When the oxidation reaction and the reduction reaction are carried out at the same temperature, exergy loss due to temperature changes in each reactor is reduced, and the energy efficiency of the gas production system can be improved.

[0023] As described above, the hydrogen generator 13 generates hydrogen as the reducing gas G3, and the system of the hydrogen generator 13 can be selected from, for example, a solid oxide electrolysis cell, steam methane reforming, etc. In particular, the use of a solid oxide electrolysis cell is preferable because hydrogen can be generated using only steam as a raw material.

[0024] The temperature of the hydrogen generator 13 is set to a temperature appropriate for hydrogen generation depending on the method. For example, a temperature of 600 to 800°C is preferable for a solid oxide electrolysis cell, and a temperature of 500 to 1000°C is preferable for steam methane reforming. The lower the temperature of the hydrogen generator 13, the less thermal energy is required to raise the temperature, and the lower the heat resistance required for the components of the hydrogen generator 13, making it possible to reduce the equipment costs, running costs, etc. of the gas production system. Furthermore, the closer the temperature of the hydrogen generator 13 is to the temperatures of each reactor, the less exergy loss caused by temperature changes in the reducing gas G3, improving the energy efficiency of the gas production system. In this embodiment, hydrogen is generated and supplied by the hydrogen generator 13, but the hydrogen generator 13 may be omitted and, for example, purchased hydrogen may be supplied.

[0025] The operation of the gas production system 100 configured as above will be described below. FIG. 2 is a flowchart showing the method of operating the gas production system 100 according to the first embodiment. The following describes a case where the reducing agent provided inside each reactor contains Fe, and the first reducing agent Fe3O4 is provided inside the first reactor 41. Before the gas production system 100 is put into operation, all of the regulating valves are controlled to be in a closed state.

[0026] <Mode 1: Oxygen reaction step S1> First, the control unit 50 controls the regulating valve 21 between the raw material gas supply unit 11 and the first reactor 41 to an open state. As a result, a raw material gas G1A containing carbon dioxide CO2 and oxygen O2 is supplied from the raw material gas supply unit 11 into the first reactor 41. After the raw material gas G1A is supplied into the first reactor 41, the control unit 50 controls the regulating valve 21 to a closed state.

[0027] Inside the first reactor 41, the raw material gas G1A and the oxidized first reducing agent Fe3O4 come into contact with each other and react with each other, thereby removing oxygen O2 from the raw material gas G1A and completely oxidizing the first reducing agent Fe3O4 to Fe2O3, as shown in the following (Equation 1). The oxygen concentration in the raw material gas after this reaction is not particularly limited, but the lower the concentration, the better. Here, the oxygen concentration in the raw material gas after the reaction depends on various conditions, such as the amount of the first reducing agent Fe3O4, the oxygen concentration in the raw material gas G1A at the time of supply to the first reactor 41, and the contact time between the first reducing agent Fe3O4 and the raw material gas G1A, and therefore may be adjusted to an oxygen concentration that optimizes the efficiency of the entire system in consideration of these conditions.

[0028]

number

[0029] <Mode 2: First Transfer Step S2> The control unit 50 controls both the regulating valves 31 and 32 provided in the circulation pipe L6A to be in an open state, and transfers the fully oxidized Fe2O3 as the second reducing agent Fe2O3 into the third reactor 43 via the circulation pipe L6A. After the second reducing agent Fe2O3 is transferred into the third reactor 43, the control unit 50 controls the regulating valves 31 and 32 to be in a closed state.

[0030] <Mode 3: Hydrogen reaction process S3> The control unit 50 controls the regulating valve 22 between the hydrogen generator 13 and the third reactor 43 to an open state. As a result, the hydrogen-containing reducing gas G3 is supplied from the hydrogen generator 13 into the third reactor 43. After the reducing gas G3 is supplied into the third reactor 43, the control unit 50 controls the regulating valve 22 to a closed state. Inside the third reactor 43, the reducing gas G3 containing hydrogen comes into contact with and reacts with the fully oxidized second reducing agent Fe2O3, whereby the second reducing agent Fe2O3 is reduced to Fe and water vapor G4 is generated, as shown in the following formula (2).

[0031]

number

[0032] The control unit 50 controls the regulating valve 25 between the third reactor 43 and the water vapor exhaust device 14 to an open state, and after the generated water vapor G4 is exhausted through the water vapor exhaust device 14, controls the regulating valve 25 to a closed state.

[0033] <Mode 4: Second Transfer Step S4> The control unit 50 controls both of the adjustment valves 33 and 34 provided in the circulation pipe L6B to an open state, and transfers the Fe reduced by contact with the reducing gas G3 as a third reducing agent Fe into the second reactor 42 via the circulation pipe L6B. After the third reducing agent Fe is transferred into the second reactor 42, the control unit 50 controls the regulating valves 33 and 34 to be in a closed state.

[0034] <Mode 5: Carbon dioxide reduction step S5> The control unit 50 controls the adjustment valve 23 between the first reactor 41 and the second reactor 42 to an open state. As a result, the raw material gas G1B as the first B gas from which oxygen has been removed by contact with the first reducing agent Fe3O4 is supplied from the first reactor 41 into the second reactor 42. After the raw material gas G1B is supplied into the second reactor 42, the control unit 50 controls the regulating valve 23 to a closed state.

[0035] Inside the second reactor 42, the raw material gas G1B from which oxygen has been removed comes into contact with and reacts with the third reducing agent Fe, whereby the third reducing agent is oxidized to Fe3O4 and the carbon dioxide CO2 in the raw material gas G1B is reduced to carbon monoxide CO to produce a product gas G2, as shown in the following formula (3).

[0036]

number

[0037] The control unit 50 controls the regulating valve 24 between the product gas discharge unit 12 and the second reactor 42 to an open state, and after discharging the generated product gas G2 through the product gas discharge unit 12, controls the regulating valve 24 to a closed state.

[0038] <Mode 6: 3rd transfer process S6> The control unit 50 controls both the adjustment valves 35 and 36 provided on the circulation pipe L6C to be open, and transfers Fe3O4 oxidized by contact with the raw material gas G1B into the first reactor 41 as the first reducing agent Fe3O4. After the first reducing agent Fe3O4 is transferred into the first reactor 41, the control unit 50 controls the regulating valves 35 and 36 to be in a closed state.

[0039] By repeating the above modes 1 to 6, oxygen in the source gas can be efficiently removed without the need for expensive, power-hungry equipment such as an oxygen removal device. This allows the product gas to be produced cheaply and efficiently. In particular, the exhaust gas can be directly treated using a reducing agent, and the reducing agent is circulated between reactors using an oxidation-reduction reaction, allowing the reducing agent to be effectively used in each reactor, which not only reduces costs but also enables further improvements in gas production efficiency.

[0040] At the start of the above-mentioned production process in which modes 1 to 6 are performed, if, for example, the third reducing agent Fe is already present in the second reactor 42, the carbon dioxide reduction step in mode 5 can be performed immediately after the execution of the oxygen reaction step in mode 1. Each of the above modes may be performed by appropriately adjusting the order in which the control valves are opened and closed so that the oxidation-reduction reaction in which the reducing agent is circulated in each reactor is carried out. In the above description, the control unit 50 controls the opening and closing of each regulating valve, but this is not limited to this. The control unit 50 may be omitted, and an operator may manually open and close each regulating valve. Furthermore, if the raw material gas contains substances that corrode the reducing agent, such as nitrogen oxides and sulfur oxides, it is desirable to reduce the amount of these substances in the raw material gas in advance using a detoxification device or the like.

[0041] A gas production system 100A having a different configuration from the gas production system 100 shown in FIG. 1 will be described below. FIG. 3 is a block diagram showing a schematic configuration of the gas production system 100A according to the first embodiment.

[0042] 1 includes three independently configured reactors: a first reactor 41, a second reactor 42, and a third reactor 43. In the present gas production system 100A, only one reactor 40A is provided as a reaction section. Furthermore, this reactor 40A is not provided with a circulation pipe for circulating a reducing agent. A raw material gas supply unit 11, a produced gas discharge unit 12, a hydrogen generator 13, and a water vapor discharge unit 14 are connected to this reactor 40A.

[0043] The operation modes 1, 3, and 5 described below are the same as the operation modes shown in Fig. 2, and when gas is supplied in each mode, the supply of gases other than the target gas is stopped by opening and closing the regulating valve to allow the reaction to proceed. Specifically, the gas production system 100A operates as follows. The following description will be given of a case where the first reducing agent Fe3O4 is provided as the reducing agent inside the reactor 40A. Before the gas producing system 100A is put into operation, all of the regulating valves are controlled to be in a closed state.

[0044] <Mode 1: Oxygen reaction process> First, the control unit 50 controls the regulating valve 21 between the raw material gas supply unit 11 and the reactor 40A to an open state. As a result, a raw material gas G1A containing carbon dioxide CO2 and oxygen O2 is supplied from the raw material gas supply unit 11 into the reactor 40A. After the raw material gas G1A is supplied into the reactor 40A, the control unit 50 controls the regulating valve 21 to a closed state.

[0045] Inside the reactor 40A, the raw material gas G1A comes into contact with and reacts with the oxidized first reducing agent Fe3O4, thereby removing oxygen O2 and completely oxidizing the first reducing agent Fe3O4 to the second reducing agent Fe2O3. The raw material gas G1B as the first B gas from which oxygen has been removed by contact with the first reducing agent Fe3O4 is mainly stored in the oxygen removal pipe L2 from the first reactor 41.

[0046] <Mode 3: Hydrogen reaction process> The control unit 50 controls the regulating valve 22 between the hydrogen generator 13 and the reactor 40A to an open state. As a result, the hydrogen-containing reducing gas G3 is supplied into the reactor 40A from the hydrogen generator 13. After the reducing gas G3 is supplied into the reactor 40A, the control unit 50 controls the regulating valve 22 to a closed state. Inside the reactor 40A, the reducing gas G3 containing hydrogen comes into contact with and reacts with the fully oxidized second reducing agent Fe2O3, reducing the second reducing agent Fe2O3 to the third reducing agent Fe and generating water vapor G4.

[0047] The control unit 50 controls the regulating valve 25 between the reactor 40A and the water vapor exhaust device 14 to an open state, and after the generated water vapor G4 is exhausted through the water vapor exhaust device 14, controls the regulating valve 25 to a closed state.

[0048] <Mode 5: Carbon dioxide reduction process> The control unit 50 controls the adjustment valve 23 to an open state. As a result, the raw material gas G1B as the first B gas from which oxygen has been removed by contact with the first reducing agent Fe3O4 is supplied from the oxygen removal pipe L2 into the reactor 40A. Inside the reactor 40A, the raw material gas G1B from which oxygen has been removed comes into contact with and reacts with the third reducing agent Fe, whereby the third reducing agent Fe is oxidized to the first reducing agent Fe3O4, and a product gas G2 is generated in which carbon dioxide CO2 in the raw material gas G1B is reduced to carbon monoxide CO.

[0049] The control unit 50 controls the regulating valve 24 between the product gas discharge unit 12 and the reactor 40A to an open state, and after discharging the generated product gas G2 through the product gas discharge unit 12, controls the regulating valve 24 to a closed state.

[0050] Here, the adjusting valve 23 functions as a partition wall that separates the source gas G1B from the second reducing agent Fe2O3 and the reducing gas G3 when the second reducing agent Fe2O3 and the reducing gas G3 come into contact with each other, thereby increasing the efficiency of gas production. The diameter and length of the oxygen removal pipe L2 are adjusted so that it has a capacity capable of temporarily storing the source gas G1B as the first B gas from which oxygen has been removed by contact with the first reducing agent Fe3O4.

[0051] As another example of the partition wall separating the source gas G1B, from which oxygen O2 has been removed by contact with the first reducing agent Fe3O4, from the second reducing agent Fe2O3 and the reducing gas G3, a wall may be provided inside the reactor 40A. In the gas production system 100 described above, the walls of the containers constituting the second reactor 42 and the third reactor 43 function as the partition wall. However, even in a configuration without the partition wall, it is possible to perform each of the oxygen reaction process, the hydrogen reaction process, and the carbon dioxide reduction process.

[0052] By adopting the above-described configuration, compared to a configuration in which three independent reactors are provided and piping is provided to circulate the reducing agent between the reactors, the manufacturing costs of the reactors, i.e., the overall cost of the gas production system, can be reduced, and the control of the adjustment valve in the control unit 50 can also be simplified.

[0053] The gas production system of this embodiment configured as described above includes: a switching unit provided in the flow path and configured to adjust opening and closing of the flow path; a hollow reaction section connected to the flow path and containing a reducing agent therein; The reaction section is The gas supply system is connected via the flow path to a first supply unit that supplies a first A gas containing carbon dioxide and oxygen and a second supply unit that supplies a reducing gas, By adjusting the opening and closing of the flow path by the switching unit, in the reaction unit, a contact between the first A gas supplied from the first supply unit and a first reducing agent as the reducing agent containing a metal oxide; a contact between a second reducing agent as the first reducing agent in contact with the first A gas and the reducing gas; and a contact between a third reducing agent as the second reducing agent in contact with the reducing gas and a first B gas as the first A gas in contact with the first reducing agent. It is something. Further, the method for operating the gas production system of the present embodiment configured as described above includes the steps of: an oxygen reaction step of contacting a first A gas containing carbon dioxide and oxygen with a first reducing agent containing a metal oxide to produce a first B gas from which the oxygen in the first A gas has been removed; a hydrogen reaction step in which a second reducing agent, which is the first reducing agent oxidized by the oxygen in the first A gas, is brought into contact with a reducing gas containing hydrogen to generate a third reducing agent by reducing the second reducing agent; a carbon dioxide reaction step in which the third reducing agent is brought into contact with the first B gas to reduce the carbon dioxide in the first B gas and generate a product gas containing carbon monoxide, and the third reducing agent is oxidized to generate the first reducing agent to be used in the oxygen reaction step. It is something.

[0054] This eliminates the need for expensive, power-hungry equipment such as an oxygen removal device, and enables efficient removal of oxygen from the raw material gas, thereby enabling the production of a product gas at low cost and with high production efficiency. In particular, the exhaust gas can be directly treated using a reducing agent, and the reducing agent is effectively utilized in the reactor using an oxidation-reduction reaction, which allows for cost reduction and further improvement in gas production efficiency.

[0055] In addition, in the gas production system of the present embodiment configured as described above, The reaction section is a partition wall that separates the first B gas from the second reducing agent and the reducing gas during contact between the second reducing agent and the reducing gas; It is something. Further, the method for operating the gas production system of the present embodiment configured as described above includes the steps of: Before the hydrogen reaction step of contacting the second reducing agent with the reducing gas, separating the first B gas from the second reducing agent and the reducing gas; It is something.

[0056] This improves the reaction efficiency in the hydrogen reaction step and the carbon dioxide reduction step, thereby increasing the gas production efficiency.

[0057] In addition, in the gas production system of the present embodiment configured as described above, The reaction section is a first reaction section that brings the first A gas supplied from the first supply section into contact with the first reducing agent; a second reaction section connected to a downstream side of the first reaction section via the flow path, to which the first B gas is supplied and which brings the third reducing agent into contact with the first B gas; a third reaction section that brings the second reducing agent into contact with the reducing gas; a first transfer section that transfers the second reducing agent from the first reaction section to the third reaction section; a second transfer section that transfers the third reducing agent from the third reaction section to the second reaction section; and a third transfer section that transfers the first reducing agent, which is the third reducing agent that has contacted the first B gas, from the second reaction section to the first reaction section. It is something. Further, the method for operating the gas production system of the present embodiment configured as described above includes the steps of: a first transfer step of transferring the second reducing agent in the first reaction section to a third reaction section that brings the second reducing agent into contact with the reducing gas after the oxygen reaction step in a first reaction section that brings the first A gas into contact with the first reducing agent; a second transfer step of transferring the third reducing agent in the third reaction section to a second reaction section that brings the third reducing agent into contact with the first B gas after the hydrogen reaction step; a third transfer step of transferring the first reducing agent in the second reaction section to the first reaction section after the carbon dioxide reaction step, It is something.

[0058] In this way, the reducing agent is circulated between the reactors using an oxidation-reduction reaction, and the reducing agent is effectively utilized in each reactor, which reduces costs and improves gas production efficiency.

[0059] The hardware configuration of the control unit 50 will now be described. FIG. 4 is a diagram showing an example of the hardware configuration of the control unit 50 as a control device. As shown in FIG. 4, the control device includes a processor 51 and a storage device 52. The storage device 52 includes a volatile storage device such as a random access memory and a non-volatile auxiliary storage device such as a flash memory, both of which are not shown. Also, an auxiliary storage device such as a hard disk may be provided instead of flash memory. Processor 51 executes a program input from storage device 52. In this case, the program is input from the auxiliary storage device to processor 51 via a volatile storage device. Processor 51 may output data such as calculation results to a volatile storage device of storage device 52, or may store data in the auxiliary storage device via the volatile storage device.

[0060] Embodiment 2 Hereinafter, the second embodiment will be described with reference to the drawings, focusing on the differences from the first embodiment. The same parts as those in the first embodiment will be given the same reference numerals and the description thereof will be omitted. FIG. 5 is a block diagram showing a schematic configuration of a gas production system 200 according to the second embodiment. The gas production system 200 includes a switching reactor 245A, a switching reactor 245B, and a switching reactor 245C, which are switching reaction sections independently configured as hollow reaction sections containing a reducing agent inside. In the following description, when there is no need to distinguish between the switching reactor 245A, the switching reactor 245B, and the switching reactor 245C, they may be simply referred to as switching reactors.

[0061] The raw material gas supply unit 11 is connected to each of the switching reactors 245A, 245B, and 245C via raw material gas pipes L201 serving as flow paths. The hydrogen generator 13 is connected to each of the switching reactors 245A, 245B, and 245C via a reducing gas pipe L204 serving as a flow path. Furthermore, although the produced gas discharge section 12 is not shown in Figure 5, it is provided in the same manner as in embodiment 1, and this produced gas discharge section 12 is connected to each of the switching reactors 245A, 245B, and 245C via the produced gas pipe L203. Although the water vapor exhaust device 14 is not shown in FIG. 5, it is provided in the same manner as in the first embodiment, and the water vapor exhaust device 14 is connected to each of the switching reactors 245A, 245B, and 245C via the water vapor exhaust pipe L205. Furthermore, the switching reactors 245A, 245B, and 245C are connected to one another via an oxygen removal pipe L202.

[0062] Furthermore, the gas production system 200 is provided with regulating valves as switching units that control the opening and closing of each pipe at the upstream and downstream stages of each switching reactor. Specifically, adjustment valves 261, 262, and 263 serving as first switching units are provided between the raw material gas supply unit 11 and the switching reactors 245A, 245B, and 245C, respectively. Furthermore, between the hydrogen generator 13 and the switching reactors 245A, 245B, and 245C, adjustment valves 264, 265, and 266 are provided as second switching units, respectively. Furthermore, adjustment valves 267, 268, and 269 serving as third switching units are provided between the switching reactors 245A, 245B, and 245C.

[0063] 5, the heaters 1, 2, and 3 and the control unit 50 shown in the first embodiment are not shown. Also, adjustment valves serving as switching units (not shown) are provided on the product gas pipe L203 and the steam discharge pipe L205 connected to each switching reactor.

[0064] The operation of the gas production system 200 configured as above will be described below. FIG. 6 is a diagram for explaining the reaction state of each switching reactor in the first step in the gas production system 200 according to the second embodiment. FIG. 7 is a diagram for explaining the reaction state of each switching reactor in the second step in the gas production system 200 according to the second embodiment. FIG. 8 is a diagram for explaining the reaction state of each switching reactor in the second step in the gas production system 200 according to the second embodiment.

[0065] Here, a case will be described in which the reducing agent provided inside each switching reactor contains Fe, and the first reducing agent Fe3O4 is provided inside the switching reactor 245A, the third reducing agent Fe is provided inside the switching reactor 245B, and the second reducing agent Fe2O3 is provided inside the switching reactor 245C. Before the gas production system 200 is put into operation, all of the regulating valves are controlled to be in a closed state.

[0066] 6, the control unit 50 controls the regulating valve 261 between the raw material gas supply unit 11 and the switching reactor 245A to an open state, and also controls the regulating valves 267 and 268 between the switching reactor 245A and the switching reactor 245B to an open state. At the same time, the control unit 50 controls the regulating valve 266 between the hydrogen generation device 13 and the switching reactor 245C to an open state.

[0067] As a result, as shown by the solid line in FIG. 6, a raw material gas G1A containing carbon dioxide CO2 and oxygen O2 is supplied from the raw material gas supply unit 11 into the switching reactor 245A. Inside the switching reactor 245A, the raw material gas G1A and the first reducing agent Fe3O4 come into contact with each other and react with each other, thereby removing oxygen O2 from the raw material gas G1A and completely oxidizing the first reducing agent Fe3O4 to the second reducing agent Fe2O3. Furthermore, the raw material gas G1B, from which oxygen has been removed by contact with the first reducing agent Fe3O4, is supplied from the switching reactor 245A into the switching reactor 245B via the oxygen removal pipe L202.

[0068] Inside the switching reactor 245B, the raw material gas G1B comes into contact with the third reducing agent Fe and reacts with it, whereby the third reducing agent Fe is oxidized to the first reducing agent Fe3O4 and carbon dioxide CO2 in the raw material gas G1B is reduced to carbon monoxide CO to produce a product gas G2. The product gas G2 is discharged from the product gas discharge unit 12 via the product gas piping L203.

[0069] As shown by the broken line in FIG. 6, a reducing gas G3 containing hydrogen is supplied from the hydrogen generator 13 into the switching reactor 245C. In the switching reactor 245C, the hydrogen-containing reducing gas G3 comes into contact with the second reducing agent FeO and reacts with it, reducing the second reducing agent FeO to the third reducing agent Fe and generating water vapor G4. The water vapor G4 is discharged from the water vapor discharge device 14 via the water vapor discharge pipe L205.

[0070] As described above, in the first step, by controlling the opening and closing of each regulating valve by the control unit 50, the switching reactor 245A functions as a first reaction unit that carries out an oxygen reaction step in which the source gas G1A is brought into contact with the first reducing agent Fe3O4. The switching reactor 245B functions as a second reaction unit that carries out a carbon dioxide reaction step in which the source gas G1B from which oxygen has been removed is brought into contact with the third reducing agent Fe. The switching reactor 245C functions as a third reaction unit that carries out a hydrogen reaction step in which the reducing gas G3 is brought into contact with the second reducing agent Fe2O3. After the first step is performed, the control unit 50 controls all the regulating valves to be in a closed state.

[0071] By carrying out this first step, the inside of the switching reactor 245A is provided with the second reducing agent Fe2O3, the inside of the switching reactor 245B is provided with the first reducing agent Fe3O4, and the inside of the switching reactor 245C is provided with the third reducing agent Fe.

[0072] 7, the control unit 50 controls the adjustment valve 262 between the raw material gas supply unit 11 and the switching reactor 245B to an open state, and also controls the adjustment valves 268 and 269 between the switching reactor 245B and the switching reactor 245C to an open state. At the same time, the control unit 50 controls the adjustment valve 264 between the hydrogen generation device 13 and the switching reactor 245A to an open state.

[0073] As a result, as shown by the solid line in FIG. 7, the raw material gas G1A containing carbon dioxide CO2 and oxygen O2 is supplied from the raw material gas supply unit 11 into the switching reactor 245B. Inside the switching reactor 245B, the raw material gas G1A and the first reducing agent Fe3O4 come into contact with each other and react with each other, thereby removing oxygen O2 from the raw material gas G1A and completely oxidizing the first reducing agent Fe3O4 to the second reducing agent Fe2O3. Furthermore, the raw material gas G1B, from which oxygen has been removed by contact with the first reducing agent Fe3O4, is supplied from the switching reactor 245B into the switching reactor 245C via the oxygen removal pipe L202.

[0074] Inside the switching reactor 245C, the raw material gas G1B comes into contact with the third reducing agent Fe and reacts with each other, whereby the third reducing agent Fe is oxidized to the first reducing agent Fe3O4 and carbon dioxide CO2 in the raw material gas G1B is reduced to carbon monoxide CO to produce a product gas G2. The product gas G2 is discharged from the product gas discharge unit 12 via the product gas piping L203.

[0075] As indicated by the broken line in FIG. 7, a reducing gas G3 containing hydrogen is supplied from the hydrogen generator 13 into the switching reactor 245A. In the switching reactor 245A, the reducing gas G3 containing hydrogen comes into contact with the second reducing agent FeO and reacts with it, reducing the second reducing agent FeO to the third reducing agent Fe and generating water vapor G4. The water vapor G4 is discharged from the water vapor discharge device 14 via the water vapor discharge pipe L205.

[0076] As described above, in the second step, by controlling the opening and closing of each regulating valve by the control unit 50, the switching reactor 245B functions as a first reaction unit that carries out an oxygen reaction step in which the source gas G1A is brought into contact with the first reducing agent Fe3O4. The switching reactor 245C functions as a second reaction unit that carries out a carbon dioxide reaction step in which the source gas G1B from which oxygen has been removed is brought into contact with the third reducing agent Fe. The switching reactor 245A functions as a third reaction unit that carries out a hydrogen reaction step in which the reducing gas G3 is brought into contact with the second reducing agent Fe2O3. After the second step is performed, the control unit 50 controls all the regulating valves to a closed state.

[0077] By carrying out this second step, the inside of the switching reactor 245A is provided with the third reducing agent Fe, the inside of the switching reactor 245B is provided with the second reducing agent Fe2O3, and the inside of the switching reactor 245C is provided with the first reducing agent Fe3O4.

[0078] 8, the control unit 50 controls the adjustment valve 263 between the raw material gas supply unit 11 and the switching reactor 245C to an open state, and also controls the adjustment valves 267 and 269 between the switching reactor 245C and the switching reactor 245A to an open state. At the same time, the control unit 50 controls the adjustment valve 265 between the hydrogen generation device 13 and the switching reactor 245B to an open state.

[0079] As a result, as shown by the solid line in FIG. 8, a raw material gas G1A containing carbon dioxide CO2 and oxygen O2 is supplied from the raw material gas supply unit 11 into the switching reactor 245C. Inside the switching reactor 245C, the raw material gas G1A and the first reducing agent Fe3O4 come into contact with each other and react with each other, thereby removing oxygen O2 from the raw material gas G1A and completely oxidizing the first reducing agent Fe3O4 to the second reducing agent Fe2O3. Furthermore, the raw material gas G1B, from which oxygen has been removed by contact with the first reducing agent Fe3O4, is supplied from the switching reactor 245C into the switching reactor 245A via the oxygen removal pipe L202.

[0080] Inside the switching reactor 245A, the raw material gas G1B comes into contact with the third reducing agent Fe and reacts with each other, whereby the third reducing agent Fe is oxidized to the first reducing agent Fe3O4 and carbon dioxide CO2 in the raw material gas G1B is reduced to carbon monoxide CO to produce a product gas G2. The product gas G2 is discharged from the product gas discharge unit 12 via the product gas piping L203.

[0081] As indicated by the broken line in FIG. 8, a reducing gas G3 containing hydrogen is supplied from the hydrogen generator 13 into the switching reactor 245B. In the switching reactor 245B, the hydrogen-containing reducing gas G3 comes into contact with the second reducing agent FeO and reacts with it, reducing the second reducing agent FeO to the third reducing agent Fe and generating water vapor G4. The water vapor G4 is discharged from the water vapor discharge device 14 via the water vapor discharge pipe L205.

[0082] As described above, in the third step, by controlling the opening and closing of each regulating valve by the control unit 50, the switching reactor 245C functions as a first reaction unit that carries out an oxygen reaction step in which the source gas G1A is brought into contact with the first reducing agent Fe3O4. The switching reactor 245A functions as a second reaction unit that carries out a carbon dioxide reaction step in which the source gas G1B from which oxygen has been removed is brought into contact with the third reducing agent Fe. The switching reactor 245B functions as a third reaction unit that carries out a hydrogen reaction step in which the reducing gas G3 is brought into contact with the second reducing agent Fe2O3. After carrying out this third step, the control unit 50 controls all the regulating valves to a closed state.

[0083] By carrying out this third step, the inside of the switching reactor 245A is provided with the first reducing agent Fe3O4, the inside of the switching reactor 245B is provided with the third reducing agent Fe, and the inside of the switching reactor 245C is provided with the second reducing agent Fe2O3.

[0084] After the third step is performed, the first step shown in FIG. 6 is performed. The above-described switching from the first process to the second process, the second process to the third process, and the third process to the first process, which are performed by switching the opening and closing of each control valve, are referred to as switching processes. That is, the switching process is the switching of the opening and closing of each control valve, which causes the switching reaction section that functioned as the first reaction section to function as the third reaction section, the switching reaction section that functioned as the second reaction section to function as the first reaction section, and the switching reaction section that functioned as the third reaction section to function as the second reaction section. This allows the reducing agent to be effectively used in each switching reactor using an oxidation-reduction reaction, thereby reducing costs and improving gas production efficiency.

[0085] In this embodiment, the control unit 50 is described as controlling the opening and closing of each regulating valve, but this is not limited to this, and each regulating valve may be opened and closed manually by an operator.

[0086] In the gas production system of this embodiment configured as described above, The reaction section is configured to have three independent switching reaction sections, each of the switching reaction units is connected to the first supply unit and the second supply unit via the flow path, and the switching reaction units are connected to each other via the flow path; By adjusting the opening and closing of the flow path by the switching unit, each of the switching reaction units is configured to function as any of a first reaction unit that brings the first reducing agent into contact with the first A gas supplied from the first supply unit, a second reaction unit that receives the first B gas and brings the third reducing agent into contact with the first B gas, and a third reaction unit that brings the second reducing agent into contact with the reducing gas. It is something.

[0087] This achieves the same effects as in the first embodiment, and eliminates the need for expensive, power-hungry equipment such as an oxygen removal device, allowing oxygen in the raw material gas to be removed efficiently, thereby enabling the production of a product gas at low cost and with high production efficiency. Furthermore, by adjusting the opening and closing of each flow path using the switching unit, each switching reaction unit can almost simultaneously function as a first reaction unit that carries out an oxygen reaction step by contacting a source gas containing carbon dioxide and oxygen with a first reducing agent, a second reaction unit that carries out a carbon dioxide reaction step by contacting a source gas from which oxygen has been removed with a third reducing agent, and a third reaction unit that carries out a hydrogen reaction step by contacting a reducing gas with the second reducing agent, thereby improving gas production efficiency.

[0088] In addition, in the method for operating the gas production system of the present embodiment configured as described above, after the step of causing each of the switching reaction units to function as any of the first reaction unit, the second reaction unit, and the third reaction unit, a switching step of causing the switching reaction unit that has functioned as the first reaction unit to function as the third reaction unit, causing the switching reaction unit that has functioned as the second reaction unit to function as the first reaction unit, and causing the switching reaction unit that has functioned as the third reaction unit to function as the second reaction unit by adjusting the opening and closing of the flow path by the switching unit; It is something.

[0089] This allows the reducing agent to be effectively used in each switching reactor by using an oxidation-reduction reaction, thereby reducing costs and improving gas production efficiency.

[0090] Although the present disclosure describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to application to a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not exemplified are conceivable within the scope of the technology disclosed in this specification, including, for example, cases where at least one component is modified, added, or omitted, and cases where at least one component is extracted and combined with components of another embodiment. [Explanation of symbols]

[0091] 11 raw material gas supply unit (first supply unit), 13 hydrogen generation device (second supply unit), 21, 261, 262, 263 regulating valve (first switching unit), 22, 264, 265, 266 regulating valve (second switching unit), 267, 268, 269 regulating valve (third switching unit), 40A reactor (reaction unit), 41 first reactor (first reaction unit), 42 second reactor (second reaction unit), 43 third reactor (third reaction unit), 245A, 245B, 245C switching reactor (switching reaction unit), L1, L201 raw material gas piping (flow path), L4, L204 reducing gas piping (flow path), L2, L202 oxygen removal piping (flow path), 100, 100A, 200 gas production system.

Claims

1. a switching unit provided in the flow path and configured to adjust opening and closing of the flow path; a hollow reaction section connected to the flow path, containing a metal that reduces carbon dioxide and having a reducing agent therein that is reduced by hydrogen, The reaction section is The gas supply system is connected via the flow path to a first supply unit that supplies a first A gas containing carbon dioxide and oxygen and a second supply unit that supplies a reducing gas containing hydrogen, By adjusting the opening and closing of the flow path by the switching unit, in the reaction unit, a contact between the first A gas supplied from the first supply unit and a first reducing agent serving as the reducing agent containing a metal oxide; a contact between a second reducing agent, which is the first reducing agent in contact with the first A gas, and the reducing gas; and a contact between a third reducing agent, which is the second reducing agent in contact with the reducing gas, and a first B gas, which is the first A gas in contact with the first reducing agent. Gas production system.

2. The reaction section is a partition wall that separates the first B gas from the second reducing agent and the reducing gas when the second reducing agent and the reducing gas are in contact with each other; The gas production system according to claim 1 .

3. The reaction section is a first reaction section that brings the first A gas supplied from the first supply section into contact with the first reducing agent; a second reaction section connected to a downstream side of the first reaction section via the flow path, to which the first B gas is supplied and to which the third reducing agent is brought into contact with the first B gas; a third reaction section that brings the second reducing agent into contact with the reducing gas; a first transfer section that transfers the second reducing agent from the first reaction section to the third reaction section; a second transfer section that transfers the third reducing agent from the third reaction section to the second reaction section; a third transfer unit that transfers the first reducing agent, which is the third reducing agent that has contacted the first B gas, from the second reaction unit to the first reaction unit; The gas production system according to claim 1 or 2.

4. The reaction section is configured to have three independent switching reaction sections, each of the switching reaction units is connected to the first supply unit and the second supply unit via the flow path, and the switching reaction units are connected to each other via the flow path; By adjusting the opening and closing of the flow path by the switching unit, each of the switching reaction units is configured to function as any of a first reaction unit that brings the first A gas supplied from the first supply unit into contact with the first reducing agent, a second reaction unit that receives the first B gas and brings the third reducing agent into contact with the first B gas, and a third reaction unit that brings the second reducing agent into contact with the reducing gas. The gas production system according to claim 1 or 2.

5. An oxygen reaction step in which a first A gas containing carbon dioxide and oxygen is contacted with a first reducing agent containing a metal oxide to produce a first B gas from which the oxygen in the first A gas has been removed; a hydrogen reaction step in which a second reducing agent, which is the first reducing agent oxidized by the oxygen in the first A gas, is brought into contact with a reducing gas containing hydrogen to generate a third reducing agent by reducing the second reducing agent; a carbon dioxide reaction step in which the third reducing agent is brought into contact with the first B gas to reduce the carbon dioxide in the first B gas to generate a product gas containing carbon monoxide, and the third reducing agent is oxidized to generate the first reducing agent to be used in the oxygen reaction step. Methods for operating gas production systems.

6. Before the hydrogen reaction step of contacting the second reducing agent with the reducing gas, separating the first B gas from the second reducing agent and the reducing gas; The method for operating the gas production system according to claim 5 .

7. a first transfer step of transferring the second reducing agent in the first reaction section to a third reaction section that brings the second reducing agent into contact with the reducing gas, after the oxygen reaction step in a first reaction section that brings the first A gas into contact with the first reducing agent; a second transfer step of transferring the third reducing agent in the third reaction section to a second reaction section that brings the third reducing agent into contact with the first B gas after the hydrogen reaction step; a third transfer step of transferring the first reducing agent in the second reaction section to the first reaction section after the carbon dioxide reaction step, A method for operating the gas production system according to claim 5 or 6.

8. A method for operating a gas production system using the gas production system according to claim 4, comprising: After the step of causing each of the switching reaction units to function as any one of the first reaction unit, the second reaction unit, and the third reaction unit, a switching step of causing the switching reaction unit that has functioned as the first reaction unit to function as the third reaction unit, causing the switching reaction unit that has functioned as the second reaction unit to function as the first reaction unit, and causing the switching reaction unit that has functioned as the third reaction unit to function as the second reaction unit by adjusting the opening and closing of the flow path by the switching unit; Methods for operating gas production systems.

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