Gas production device, gas production system, and gas production method

Abstract

To provide a gas production apparatus and a gas production system capable of efficiently producing a product gas containing carbon monoxide from a raw material gas containing carbon dioxide.SOLUTION: There is provided a production apparatus 1 for producing a product gas containing carbon monoxide by bringing a raw material gas containing carbon dioxide and a reducing agent for reducing the carbon dioxide into contact with each other, which comprises a connection part 2 for supplying a raw material gas, a reducing gas supply part 3 for supplying a reducing gas for reducing a reducing agent oxidized by contact with carbon dioxide, a plurality of reactors 4a and 4b connected to each of the connection part 2 and the reducing gas supply part 3 and a reducing agent disposed in the reactors 4a and 4b, a reaction part 4 capable of switching a raw material gas and a reducing gas supplied to each of the reactors 4a and 4b and a protector (a minute component removal part 7) which is provided between the connection part 2 and the reactors 4a and 4b and has a substance capable of trapping a component contained in a raw material gas which deteriorates the activity of a reducing agent by contact with a reducing agent.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a gas production device, a gas production system, and a gas production method. [Background technology]

[0002] In recent years, the concentration of carbon dioxide (CO2), a type of greenhouse gas, in the atmosphere has been increasing. The increase in the concentration of carbon dioxide in the atmosphere contributes to global warming. Therefore, it is important to capture carbon dioxide released into the atmosphere, and if the captured carbon dioxide can be converted into valuable substances and reused, a carbon circulation society can be realized. As a global policy, the Kyoto Protocol of the United Nations Framework Convention on Climate Change stipulates that each developed country must set its own reduction rate for carbon dioxide, the cause of global warming, using 1990 as a base year, and that they must jointly achieve reduction targets within the commitment period.

[0003] In order to achieve this reduction target, exhaust gases containing carbon dioxide generated from steel mills, smelters, and thermal power plants are also included, and various technological improvements are being made to reduce carbon dioxide in these industries. One example of such a technology is carbon capture and storage (CCS). However, this technology has physical limitations in terms of storage, and is not a fundamental solution. Additionally, for example, Patent Document 1 discloses a technology for converting carbon dioxide into a valuable substance. Specifically, the document discloses a production apparatus for producing carbon monoxide from carbon dioxide using cerium oxide containing zirconium. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5858926 Summary of the Invention [Problem to be solved by the invention]

[0005] However, according to the inventors' investigation, the invention described in Patent Document 1 is an invention that specifies a metal oxide that effectively converts carbon dioxide into carbon monoxide. Patent Document 1 only discloses conceptual or general information on the conditions and equipment for producing carbon monoxide, as shown in the drawings, and it was found that further technical improvements are necessary to produce carbon monoxide industrially. Therefore, an object of the present invention is to provide a gas production apparatus (i.e., an industrially advantageous production apparatus), a gas production system, and a gas production method capable of efficiently producing a product gas containing carbon monoxide from a raw material gas containing carbon dioxide. [Means for solving the problem]

[0006] Such an object can be achieved by the present invention described below.

[0007] (1) A gas production apparatus of the present invention is a gas production apparatus that produces a product gas containing carbon monoxide by contacting a raw material gas containing carbon dioxide with a reductant that reduces the carbon dioxide, a raw material gas supply unit for supplying the raw material gas; a reaction section connected to the raw material gas supply section and including at least one reactor for storing the reductant; and a protective device provided between the raw material gas supply unit and the reactor, the protective device having a substance capable of capturing a component contained in the raw material gas, the component decreasing activity of the reductant upon contact with the reductant.

[0008] (2) In the gas production apparatus of the present invention, the component is preferably at least one selected from the group consisting of sulfur, mercury, a sulfur compound, a halogen compound, an organosilicon compound, an organophosphorus compound, and an organometallic compound. (3) In the gas production apparatus of the present invention, it is preferable that the reactor contains the reductant that produces the carbon monoxide by a reduction reaction of the carbon dioxide generated by contact with the raw material gas, and that at least a portion of the oxygen atoms released from the carbon dioxide can be separated within the reduction reaction system.

[0009] (4) In the gas production apparatus of the present invention, the at least one reactor includes a plurality of reactors that store a reducing agent containing a metal oxide that reduces carbon dioxide as the reducing agent, The gas production apparatus further includes a reducing gas supply unit that supplies a reducing gas containing a reducing substance that reduces the reducing agent that has been oxidized by contact with the carbon dioxide, It is preferable that each of the reactors is connected to at least one of the raw material gas supply unit and the reducing gas supply unit, and that the raw material gas and the reducing gas supplied to each of the reactors can be switched or the reducing agent can be moved between the reactors. (5) The gas production apparatus of the present invention preferably further comprises a gas junction section for junctioning the gases that have passed through the reactor to produce a mixed gas.

[0010] (6) The gas production apparatus of the present invention preferably further comprises gas lines connected to each of the reactors and independent of each other. (7) The gas production apparatus of the present invention further comprises a compression section which increases a pressure of the raw material gas, and a raw material gas heating section which heats the raw material gas which has passed through the compression section and before being supplied to the reactor, The protector is preferably provided between the compression section and the raw gas heating section. (8) In the gas production apparatus of the present invention, it is preferable that the metal oxide contains at least one metal element selected from the group consisting of metal elements belonging to Groups 3 to 12.

[0011] (9) The gas production system of the present invention comprises: a raw material gas generating unit for generating a raw material gas containing carbon dioxide; The gas production apparatus of the present invention is provided, The gas production apparatus is characterized in that it is connected to the raw material gas generation unit via the raw material gas supply unit.

[0012] (10) A gas production method of the present invention includes contacting a raw material gas containing carbon dioxide with a reductant that reduces the carbon dioxide to produce a product gas containing carbon monoxide, the method comprising the steps of: providing at least one reactor for accommodating the reductant and the raw material gas; contacting the feed gas with the reductant in the reactor to convert the carbon dioxide into carbon monoxide; When recovering the gas that has passed through the reactor as the product gas, either directly or by purifying the carbon monoxide from the gas that has passed through the reactor, The method is characterized in that the raw material gas before being supplied to the reactor is contacted with a substance capable of capturing a component contained in the raw material gas and that reduces the activity of the reductant upon contact with the reductant.

[0013] (11) In the gas production method of the present invention, the at least one reactor includes a plurality of reactors that store, as the reductant, a reducing agent including a metal oxide that reduces carbon dioxide, preparing a reducing gas containing a reducing substance that reduces the reducing agent oxidized by contact with the carbon dioxide together with the plurality of reactors and the raw material gas; It is preferable that the reactors to which the raw material gas and the reducing gas are supplied are switched to alternately contact the reducing agent with the raw material gas and the reducing gas in each of the reactors, thereby converting the carbon dioxide into carbon monoxide, and then reducing the oxidized reducing agent.

[0014] (12) In the gas production method of the present invention, the gases that have passed through the reactor are joined together to generate a mixed gas; It is preferable to recover the mixed gas as the product gas directly or by purifying the carbon monoxide from the mixed gas. (13) In the gas production process of the present invention, it is preferable that the gases having passed through each of the reactors are treated independently of each other. Effect of the Invention

[0015] According to the present invention, a product gas containing carbon monoxide can be efficiently produced from a raw gas containing carbon dioxide. In particular, in the present invention, a protector having a substance capable of capturing components in the raw gas that reduce the activity of the reductant by contact with the reductant is provided in the upstream stage of the reactor, so that the above components can be prevented or inhibited from reaching the reductant in the reactor, thereby protecting the reductant (i.e., preventing a decrease in activity). Therefore, it is possible to prevent or inhibit a drastic decrease in the efficiency of conversion of carbon dioxide to carbon monoxide by the reductant due to the adverse effects of the above components. [Brief description of the drawings]

[0016] [Figure 1] 1 is a schematic diagram illustrating one embodiment of a gas production system of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view that illustrates a schematic configuration (first configuration example) of the reactor in FIG. [Diagram 3] FIG. 2 is a schematic diagram showing a configuration of an exhaust gas heating unit in FIG. [Figure 4] FIG. 2 is a schematic diagram showing a configuration of a reducing agent heating unit. [Diagram 5] FIG. 11 is a schematic diagram showing another configuration of the reducing agent heating unit. [Figure 6] 1 is a schematic diagram showing a configuration in the vicinity of a connection portion between a gas production apparatus and a furnace according to the present invention. [Figure 7] FIG. 11 is a cross-sectional view that illustrates a second configuration example of a reactor. [Figure 8] FIG. 2 is a schematic diagram showing another embodiment of the gas production system of the present invention. [Figure 9] FIG. 9 is a cross-sectional view that illustrates a schematic configuration of the refiner in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A gas production apparatus, a gas production system, and a gas production method according to the present invention will be described in detail below with reference to preferred embodiments shown in the accompanying drawings. FIG. 1 is a schematic diagram showing one embodiment of the gas production system of the present invention, FIG. 2 is a cross-sectional diagram showing a schematic configuration of the reactor of FIG. 1 (first configuration example), and FIG. 3 is a schematic diagram showing the configuration of the exhaust gas heating section of FIG. 1. The gas production system 100 shown in FIG. 1 includes a furnace (raw material gas production section) 20 that produces exhaust gas (raw material gas) containing carbon dioxide, and a gas production apparatus 1 connected to the furnace 20 via a connection section 2. In this specification, the upstream side with respect to the gas flow direction is also simply referred to as the "upstream side", and the downstream side is also simply referred to as the "downstream side".

[0018] The furnace 20 is not particularly limited, but may be, for example, a furnace attached to a steelworks, a smelter, or a thermal power plant, and preferably includes a combustion furnace, a blast furnace, a converter, etc. In the furnace 20, exhaust gas is generated (generated) when the contents are burned, melted, refined, etc. In the case of a combustion furnace (incinerator) in a waste incineration plant, the contents (waste) include, for example, plastic waste, food waste, municipal solid waste (MSW), discarded tires, biomass waste, household waste (futons, paper), building materials, etc. These wastes may contain one type alone or two or more types.

[0019] Exhaust gas usually contains, in addition to carbon dioxide, other gas components such as nitrogen, oxygen, carbon monoxide, water vapor, methane, etc. The concentration of carbon dioxide contained in the exhaust gas is not particularly limited, but considering the production cost of the generated gas (conversion efficiency to carbon monoxide), it is preferably 1 vol% or more, and more preferably 5 vol% or more. Exhaust gas from the combustion furnace at a waste incineration plant contains 5 to 15 volume percent carbon dioxide, 60 to 70 volume percent nitrogen, 5 to 10 volume percent oxygen, and 15 to 25 volume percent water vapor.

[0020] Exhaust gas from a blast furnace (blast furnace gas) is a gas generated when pig iron is produced in a blast furnace, and contains 10 to 15 volume % carbon dioxide, 55 to 60 volume % nitrogen, 25 to 30 volume % carbon monoxide, and 1 to 5 volume % hydrogen. In addition, exhaust gas from a converter (converter gas) is a gas generated when steel is produced in a converter, and contains 15 to 20 volume % carbon dioxide, 50 to 60 volume % carbon monoxide, 15 to 25 volume % nitrogen, and 1 to 5 volume % hydrogen. The raw material gas is not limited to exhaust gas, and a pure gas containing 100% by volume of carbon dioxide may be used.

[0021] However, if exhaust gas is used as the raw material gas, carbon dioxide that has conventionally been discharged into the atmosphere can be effectively utilized, and the burden on the environment can be reduced. Among these, from the viewpoint of carbon circulation, exhaust gas containing carbon dioxide generated in a steelworks or a smelter is preferred. In addition, the blast furnace gas and converter gas may be untreated gas discharged from the furnace as is, or treated gas after treatment to remove carbon monoxide, for example, may be used. Untreated blast furnace gas and converter gas each have the gas composition described above, and treated gas has a gas composition close to the gas composition shown for the exhaust gas from the combustion furnace. In this specification, all of the above gases (gases before being supplied to the gas production apparatus 1) are referred to as exhaust gas.

[0022] <Overall composition> The gas production apparatus 1 produces a product gas (synthesis gas) containing carbon monoxide by contacting exhaust gas (raw material gas containing carbon dioxide) discharged from the furnace 20 and supplied via a connection part 2 with a reducing agent containing a metal oxide that reduces the carbon dioxide contained in the exhaust gas. The gas manufacturing apparatus 1 mainly includes a connection section 2, a reducing gas supply section 3, two reactors 4a, 4b, a gas line GL1 connecting the connection section 2 to each of the reactors 4a, 4b, a gas line GL2 connecting the reducing gas supply section 3 to each of the reactors 4a, 4b, and a gas line GL4 connected to each of the reactors 4a, 4b. In this embodiment, the connection part 2 constitutes a raw material gas supply part that supplies the exhaust gas to the reactors 4a and 4b. If necessary, pumps for transferring gas may be provided at predetermined positions along the gas lines GL1, GL2, and GL4. For example, when the pressure of the exhaust gas is adjusted to a relatively low value in the compression section 6 described below, the gas can be transferred smoothly within the gas production apparatus 1 by providing the pumps.

[0023] One end of the gas line GL1 is connected to the connection unit 2. Meanwhile, the other end of the gas line GL1 is connected to the inlet ports of the reactors 4a and 4b in the reaction unit 4 via the gas switching unit 8 and two gas lines GL3a and GL3b. With this configuration, the exhaust gas supplied from the furnace 20 through the connection part 2 passes through the gas line GL1 and is supplied to each of the reactors 4a and 4b. The gas switching unit 8 can be configured to include, for example, a branch gas line and a flow path opening and closing mechanism such as a valve provided midway along the branch gas line.

[0024] As shown in Fig. 2, each of the reactors 4a and 4b is a multi-tubular reactor (fixed-bed reactor) including a plurality of tubes 41 each filled with a reducing agent (reductant) 4R and a housing 42 containing the plurality of tubes 41. Such a multi-tubular reactor can ensure sufficient opportunities for the reducing agent 4R to come into contact with the exhaust gas and the reducing gas. As a result, the production efficiency of the generated gas can be improved. The reducing agent 4R of the present embodiment is preferably in the form of, for example, particles (granules), flakes, pellets, etc. The reducing agent 4R in such a shape can increase the filling efficiency into the pipe 41, and can further increase the contact area with the gas supplied into the pipe 41. When the reducing agent 4R is particulate, its volume average particle size is not particularly limited, but is preferably 1 to 50 mm, and more preferably 3 to 30 mm. In this case, the contact area between the reducing agent 4R and the exhaust gas (carbon dioxide) can be further increased, and the conversion efficiency of carbon dioxide to carbon monoxide can be further improved. Similarly, regeneration (reduction) of the reducing agent 4R by the reducing gas containing the reducing substance can be performed more efficiently. The particulate reducing agent 4R is preferably a compact produced by rolling granulation, since this increases the sphericity.

[0025] The reducing agent 4R may be supported on a carrier. The constituent material of the carrier is not particularly limited as long as it is not easily denatured depending on the exhaust gas (raw material gas) and reaction conditions, and examples thereof include carbon materials (graphite, graphene, etc.), zeolite, montmorillonite, SiO2, ZrO2, TiO2, V2O5, MgO, alumina (Al2O3), silica, and composite oxides of these materials. Among these, zeolite, montmorillonite, SiO2, ZrO2, TiO2, V2O5, MgO, alumina (Al2O3), silica, and composite oxides of these materials are preferred. A carrier made of such a material is preferred in that it does not adversely affect the reaction of the reducing agent 4R and has excellent supporting ability for the reducing agent 4R. Here, the carrier does not participate in the reaction of the reducing agent 4R and simply supports (holds) the reducing agent 4R. One example of such a form is a configuration in which at least a part of the surface of the carrier is covered with the reducing agent 4R.

[0026] The metal oxide (oxygen carrier) contained in the reducing agent 4R is not particularly limited as long as it can reduce carbon dioxide, but it preferably contains at least one selected from metal elements belonging to groups 3 to 12, more preferably contains at least one selected from metal elements belonging to groups 4 to 12, and further preferably contains at least one of titanium, vanadium, iron, copper, zinc, nickel, manganese, chromium, and cerium, and is particularly preferably a metal oxide or composite oxide containing iron. These metal oxides are useful because they have a particularly good conversion efficiency of carbon dioxide to carbon monoxide.

[0027] In each of the reactors 4a and 4b, the tube (cylindrical molded body) 41 may be made of the reducing agent 4R (metal oxide) itself. Furthermore, a molded body such as a block or lattice (for example, a mesh or honeycomb) may be made of the reducing agent 4R and placed in the housing 42. In these cases, the reducing agent 4R may be omitted as a filler or may be used in combination. Among these, a preferred configuration is one in which a mesh body is made of the reducing agent 4R and placed in the housing 42. In the case of such a configuration, it is possible to prevent an increase in the passage resistance of the exhaust gas and the reducing gas in each of the reactors 4a, 4b, while also ensuring a sufficient opportunity for the reducing agent 4R to come into contact with the exhaust gas and the reducing gas. The volumes of the two reactors 4a, 4b are set to be approximately equal to each other, and are appropriately set according to the amount of exhaust gas to be treated (the size of the furnace 20 and the size of the gas production apparatus 1).

[0028] In the gas line GL1, a concentration adjusting section 5, a compression section 6, a minor component removing section 7, and an exhaust gas heating section (raw material gas heating section) 10 are provided in this order from the connection section 2 side. The concentration adjusting unit 5 adjusts the concentration of carbon dioxide contained in the exhaust gas to increase it (in other words, to concentrate carbon dioxide). The exhaust gas also contains unnecessary gas components such as oxygen. By increasing the concentration of carbon dioxide contained in the exhaust gas with the concentration adjusting unit 5, the concentration of the unnecessary gas components contained in the exhaust gas can be relatively lowered. This makes it possible to prevent or suppress the unnecessary gas components from adversely affecting the efficiency of conversion of carbon dioxide to carbon monoxide by the reducing agent 4R. The concentration adjusting section 5 is preferably configured with an oxygen removing device that removes oxygen contained in the exhaust gas. This makes it possible to reduce the amount of oxygen brought into the gas production apparatus 1 (i.e., adjust the concentration of oxygen contained in the exhaust gas to be lower). This makes it possible to move the gas composition of the exhaust gas away from the explosion range and prevent the exhaust gas from igniting. Note that, since the oxygen removing device in the gas production apparatus 1 consumes a large amount of electric energy, it is effective to use electricity as a renewable energy source as described below.

[0029] In this case, the concentration of oxygen contained in the exhaust gas is preferably adjusted to less than 1% by volume, more preferably less than 0.5% by volume, and even more preferably less than 0.1% by volume, relative to the total volume of the exhaust gas, thereby making it possible to more reliably prevent the exhaust gas from igniting. The oxygen removal device that removes oxygen contained in exhaust gas can be constructed using one or more of the following separators: a low-temperature separation type (cryogenic type), a pressure swing adsorption (PSA) type separator, a membrane separation type separator, a temperature swing adsorption (TSA) type separator, a chemical absorption type separator, a chemical adsorption type separator, etc. Incidentally, in the concentration adjusting section 5, carbon dioxide may be added to the exhaust gas to adjust the concentration of carbon dioxide to a high level.

[0030] The compression section 6 increases the pressure of the exhaust gas before it is supplied to the reactors 4a and 4b. This increases the amount of exhaust gas that can be treated at one time in the reactors 4a and 4b. This further improves the efficiency of converting carbon dioxide into carbon monoxide in the reactors 4a and 4b. The compression section 6 can be composed of, for example, a volumetric compressor such as a centrifugal compressor, a turbo compressor such as an axial compressor, a reciprocating compressor, a diaphragm compressor, a single screw compressor, a twin screw compressor, a scroll compressor, a rotary compressor, a rotary piston type compressor, or a slide vane type compressor, a Roots blower (two-blade blower) capable of handling low pressure, a centrifugal blower, or the like.

[0031] Of these, from the viewpoint of easiness in scaling up the gas production system 100, it is preferable that the compression section 6 be configured with a centrifugal compressor, and from the viewpoint of reducing the manufacturing costs of the gas production system 100, it is preferable that the compression section 6 be configured with a reciprocating compressor. The pressure of the exhaust gas after passing through the compression section 6 is not particularly limited, but is preferably 0 to 1 MPaG, more preferably 0 to 0.5 MPaG, and even more preferably 0.01 to 0.5 MPaG. In this case, the efficiency of converting carbon dioxide to carbon monoxide in the reactors 4a and 4b can be further improved without increasing the pressure resistance of the gas production apparatus 1 more than necessary.

[0032] The minor component removal section 7 removes minor components (such as trace amounts of unnecessary gas components) contained in the exhaust gas. The fine component removing section 7 can be composed of at least one type of treatment device among, for example, a gas-liquid separator, a guard reactor, and a scrubber (absorption tower). When multiple treatment devices are used, the order of their arrangement is arbitrary, but when a gas-liquid separator and a protective device are used in combination, it is preferable to arrange the gas-liquid separator upstream of the protective device. In this case, the efficiency of removing trace components from the exhaust gas can be further increased, and the service life (life) of the protective device can be extended.

[0033] The gas-liquid separator separates, for example, condensed water (liquid) generated when the exhaust gas is compressed in the compression section 6 from the exhaust gas. In this case, unnecessary gas components remaining in the exhaust gas are also dissolved in the condensed water and removed. The gas-liquid separator can be configured, for example, as a simple container, a swirl-flow separator, a centrifugal separator, a surface tension separator, etc. Among these, it is preferable that the gas-liquid separator is configured as a simple container because of its simple configuration and low cost, etc. In this case, a filter that allows the passage of gas but prevents the passage of liquid may be disposed at the gas-liquid interface in the container. In this case, a liquid line may be connected to the bottom of the container, and a valve may be provided on the way. With this configuration, the condensed water stored in the container can be discharged to the outside of the gas production apparatus 1 through the liquid line by opening the valve. The liquid line may be connected to a tank 30, which will be described later, so that the discharged condensed water can be reused.

[0034] The exhaust gas from which condensed water has been removed in the gas-liquid separator may be configured to be supplied to, for example, a protector. Such a protector preferably includes a substance capable of capturing minor components contained in exhaust gas that reduce the activity of the reducing agent 4R (inactivating components) by coming into contact with the reducing agent 4R. According to this configuration, when exhaust gas passes through the protector, the substance in the protector reacts (captures) with the inactivated components, thereby preventing or suppressing the exhaust gas from reaching the reducing agent 4R in the reactors 4a and 4b, thereby protecting the exhaust gas (i.e., preventing a decrease in activity). Therefore, it is possible to prevent or suppress a drastic decrease in the efficiency of conversion of carbon dioxide to carbon monoxide by the reducing agent 4R due to the adverse effect of the inactivated components.

[0035] Such a substance may be a substance having a composition contained in the reducing agent 4R that reduces the activity of the reducing agent 4R by contacting with an inactivating component, specifically, a metal oxide that is the same as or similar to the metal oxide contained in the reducing agent 4R. Here, a similar metal oxide refers to a metal oxide that contains the same metal element but has a different composition, or a metal oxide that contains different types of metal elements but belongs to the same group in the periodic table. The inactivating component is preferably at least one selected from sulfur, mercury, a sulfur compound, a halogen compound, an organic silicone, an organic phosphorus, and an organic metal compound, and more preferably at least one selected from sulfur and a sulfur compound. If such an inactivating component is removed in advance, the activity of the reducing agent 4R can be effectively prevented from decreasing rapidly. The above-mentioned substance may be any substance whose activity is reduced by the same component as the inactivating component of the reducing agent 4R, and metal oxides such as iron oxide and zinc oxide are preferred because of their excellent ability to capture the above-mentioned inactivating components.

[0036] The protective device can be configured in such a way that a mesh material is placed within a housing and particles of the above-mentioned material are placed on the mesh material, or that a honeycomb-shaped filter member or a cylindrical or granular molded body made of the above-mentioned material is placed within the housing. In particular, when the protective device is disposed between the compression section 6 (gas-liquid separator) and the exhaust gas heating section 10, it is possible to improve the efficiency of removing the inactivated components while preventing deterioration of the above-mentioned substances due to heat.

[0037] The exhaust gas heating section 10 heats the exhaust gas before it is supplied to the reactors 4a and 4b. By preheating the exhaust gas before the reaction (before reduction) in the exhaust gas heating section 10, the conversion (reduction) reaction of carbon dioxide to carbon monoxide by the reducing agent 4R can be further promoted in the reactors 4a and 4b. The exhaust gas heating section 10 can be composed of, for example, an electric heater 101 and a heat exchanger (economizer) 102, as shown in FIG. The heat exchanger 102 is configured by bending a part of the piping constituting the gas line GL4 (see below) that discharges the gas (mixed gas) after passing through the reactors 4a and 4b, and bringing it close to the piping constituting the gas line GL1. With this configuration, the heat of the high-temperature gas (mixed gas) after passing through the reactors 4a and 4b is used to heat the exhaust gas before being supplied to the reactors 4a and 4b by heat exchange, so that the heat can be effectively utilized.

[0038] The heat exchanger 102 can be configured as, for example, a jacket type heat exchanger, an immersed coil type heat exchanger, a double-pipe type heat exchanger, a shell-and-tube type heat exchanger, a plate type heat exchanger, a spiral type heat exchanger, or the like. In addition, in the exhaust gas heating section 10, either the electric heater 101 or the heat exchanger 102 may be omitted. In the exhaust gas heating section 10, a combustion furnace or the like can be used instead of the electric heater 101. However, if the electric heater 101 is used, electricity (electrical energy) as a renewable energy source can be used as the power source, so that the burden on the environment can be reduced. As the renewable energy, electric energy utilizing at least one selected from photovoltaic power generation, wind power generation, hydroelectric power generation, wave power generation, tidal power generation, biomass power generation, geothermal power generation, solar heat, and geothermal heat can be used.

[0039] In addition, an exhaust gas line may be branched off from the gas line GL1 upstream of the exhaust gas heating section 10 (for example, between the gas-liquid separator and the protector midway through the microcomponent removal section 7), and a vent section provided outside the gas manufacturing apparatus 1 may be connected to the end of the exhaust gas line. In this case, a valve is preferably provided in the exhaust gas line. If the pressure in the gas production device 1 (gas line GL1) rises more than necessary, the valve can be opened to discharge (release) part of the exhaust gas from the vent through the exhaust gas line, thereby preventing damage to the gas production device 1 due to an increase in pressure.

[0040] One end of the gas line GL2 is connected to the reducing gas supply unit 3. On the other hand, the gas line GL2 is connected to the inlet ports of reactors 4a and 4b provided in the reaction unit 4 via a gas switching unit 8 and two gas lines GL3a and GL3b, respectively. The reducing gas supply unit 3 supplies a reducing gas containing a reducing substance that reduces the reducing agent 4R oxidized by contact with carbon dioxide. The reducing gas supply unit 3 in this embodiment is composed of a hydrogen generation device that generates hydrogen by electrolysis of water, and a tank (reducing gas raw material storage unit) 30 that stores water and is outside the gas production apparatus 1 is connected to this hydrogen generation device. With this configuration, the reducing gas containing hydrogen (reducing substance) supplied from the hydrogen generation device (reducing gas supply unit 3) passes through the gas line GL2 and is supplied to each of the reactors 4a, 4b. The hydrogen generation device can generate a large amount of hydrogen relatively cheaply and easily. Another advantage is that the condensed water generated in the gas production device 1 can be reused. Since the hydrogen generation device consumes a large amount of electric energy in the gas production device 1, it is effective to use electricity as a renewable energy source as described above.

[0041] In addition, a device that generates by-product hydrogen can also be used as the hydrogen generating device. In this case, a reducing gas containing by-product hydrogen is supplied to each of the reactors 4a and 4b. Examples of devices that generate by-product hydrogen include devices that electrolyze sodium chloride aqueous solution, devices that steam reform petroleum, and devices that manufacture ammonia. Also, the gas line GL2 may be connected to a coke oven outside the gas production apparatus 1 via a connection part, and the exhaust gas from the coke oven may be used as the reducing gas. In this case, the connection part constitutes a reducing gas supply part. This is because the exhaust gas from the coke oven is mainly composed of hydrogen and methane, and contains 50 to 60 volume % of hydrogen. A reducing gas heating unit 11 is provided in the gas line GL2. This reducing gas heating unit 11 heats the reducing gas before it is supplied to the reactors 4a and 4b. By preheating the reducing gas before reaction (before oxidation) in the reducing gas heating unit 11, the reduction (regeneration) reaction of the reducing agent 4R by the reducing gas in the reactors 4a and 4b can be further promoted.

[0042] The reducing gas heating section 11 can be configured in the same manner as the above-mentioned exhaust gas heating section 10. The reducing gas heating section 11 is preferably configured with only an electric heater, only a heat exchanger, or a combination of an electric heater and a heat exchanger, and more preferably configured with only a heat exchanger, or a combination of an electric heater and a heat exchanger. If the reducing gas heating section 11 is equipped with a heat exchanger, the heat of the high-temperature gas (e.g., mixed gas) after passing through the reactors 4a, 4b is utilized to heat the reducing gas by heat exchange before being supplied to the reactors 4a, 4b, thereby enabling effective use of heat.

[0043] According to the above-mentioned configuration, by switching the gas lines (flow paths) in the gas switching unit 8, for example, exhaust gas can be supplied via the gas line GL3a to the reactor 4a containing the reducing agent 4R before oxidation, and reducing gas can be supplied via the gas line GL3b to the reactor 4b containing the reducing agent 4R after oxidation. At this time, the reaction of the following formula 1 proceeds in the reactor 4a, and the reaction of the following formula 2 proceeds in the reactor 4b. In the following formulas 1 and 2, the metal oxide contained in the reducing agent 4R is iron oxide (FeO x-1 ) is shown as an example. Formula 1: CO2+ FeO x-1 → CO + FeO x Formula 2: H2+ FeO x → HO + FeO x-1 Thereafter, by switching the gas lines in the opposite direction at gas switching section 8, the reaction of formula 2 above can be caused to proceed in reactor 4a, and the reaction of formula 1 above can be caused to proceed in reactor 4b.

[0044] The reactions shown in the above formulas 1 and 2 are both endothermic reactions. For this reason, the gas production device 1 preferably further includes a reducing agent heating unit (not shown in FIG. 1) that heats the reducing agent 4R when the exhaust gas or reducing gas is brought into contact with the reducing agent 4R (i.e., when the exhaust gas or reducing gas reacts with the reducing agent 4R). By providing such a reducing agent heating section, the temperature in the reaction between the exhaust gas or reducing gas and the reducing agent 4R can be maintained at a high temperature, thereby suitably preventing or suppressing a decrease in the conversion efficiency of carbon dioxide to carbon monoxide, and further promoting the regeneration of the reducing agent 4R by the reducing gas.

[0045] However, depending on the type of reducing agent 4R, the reactions shown in the above formulas 1 and 2 may be exothermic reactions. In this case, the gas production device 1 preferably has a reducing agent cooling unit that cools the reducing agent 4R instead of the reducing agent heating unit. By providing such a reducing agent cooling unit, it is possible to suitably prevent deterioration of the reducing agent 4R during the reaction between the exhaust gas or reducing gas and the reducing agent 4R, suitably prevent or suppress a decrease in the conversion efficiency of carbon dioxide to carbon monoxide, and further promote the regeneration of the reducing agent 4R by the reducing gas. That is, the gas production device 1 is preferably provided with a reducing agent temperature adjustment unit that adjusts the temperature of the reducing agent 4R depending on the type of reducing agent 4R (exothermic reaction or endothermic reaction). A suitable configuration of the reducing agent temperature adjustment section will be described in detail later.

[0046] The outlet ports of the reactors 4a and 4b are connected to branch gas lines GL4a and GL4b, respectively, which join at a gas junction J4 to form the gas line GL4. In addition, valves (not shown) are provided in the middle of the branch gas lines GL4a and GL4b, respectively, as necessary. For example, by adjusting the opening of the valve, the passing speed of the exhaust gas and the reducing gas passing through the reactors 4a, 4b (i.e., the treatment speed of the exhaust gas by the reducing agent 4R and the treatment speed of the reducing agent 4R by the reducing gas) can be set. In this embodiment, the reactors 4a, 4b and the gas switching unit 8 constitute the reaction unit 4.

[0047] With this configuration, the gases (mainly carbon monoxide and water vapor in this embodiment) that have passed through each of the reactors 4a and 4b are mixed by merging at the gas junction J4, and after a mixed gas (merged gas) is generated, it passes through a single gas line GL4. Therefore, by changing the flow path switching state (open / closed state of the valve) of the gas switching unit 8 and carrying out different reactions in the reactors 4a and 4b, it is possible to continuously produce the mixed gas, and ultimately the product gas can also be produced continuously. In addition, since the same reaction is repeatedly carried out alternately in the reactors 4a and 4b, the concentration of carbon monoxide contained in the mixed gas can be stabilized, and as a result, the concentration of carbon monoxide contained in the product gas can also be stabilized. Therefore, the above-described gas production apparatus 1 (gas production system 100) can continuously and stably produce carbon monoxide from carbon dioxide, which is industrially advantageous.

[0048] On the other hand, if the gas junction J4 is not provided, it becomes necessary to shut off the gas switching unit 8 (close the valve once) when switching the gas to be supplied, and each of the reactors 4a and 4b must be of a batch type. Therefore, depending on the concentration of carbon dioxide in the exhaust gas, the type of the reducing agent 4R, the capacity of the reactors 4a and 4b, etc., the time required to produce carbon monoxide may become long, resulting in poor conversion efficiency and being industrially disadvantageous. In addition, the components of the gas discharged from each of the reactors 4a and 4b are likely to change every time the gas to be supplied is switched, which may result in a complicated post-treatment process for the gas discharged from each of the reactors 4a and 4b. Here, it is usually preferable to adjust the concentration of carbon monoxide contained in the mixed gas to within a specific range (a predetermined volume % relative to the entire mixed gas). If this concentration is too low, it tends to be difficult to obtain a product gas containing a high concentration of carbon monoxide, although this depends on the performance of the gas purification section 9 described below. On the other hand, even if the concentration is increased beyond the upper limit, no further increase in the effect of increasing the concentration of carbon monoxide contained in the final product gas cannot be expected.

[0049] A produced gas discharge unit 40 that discharges the produced gas to the outside of the gas production apparatus 1 is connected to the end of the gas line GL4 opposite to the reactors 4a, 4b. Further, a gas purification section 9 is provided in the middle of the gas line GL4. In the gas purification unit 9, carbon monoxide is purified from the mixed gas, and a product gas containing a high concentration of carbon monoxide is recovered. Note that, if the concentration of carbon monoxide in the mixed gas is sufficiently high, the gas purification unit 9 may be omitted. The gas purification section 9 can be composed of at least one type of treatment device among, for example, a cooler, a gas-liquid separator, a gas separator, a separation membrane, and a scrubber (absorption tower). When multiple treatment devices are used, the order of arrangement of the devices may be arbitrary, but when a cooler, a gas-liquid separator, and a gas separator are used in combination, it is preferable to arrange them in this order, which can further increase the efficiency of purifying carbon monoxide from the mixed gas.

[0050] The cooler cools the mixed gas, which produces condensed water (liquid). Such a cooler can be configured to include a jacket-type cooling device in which a jacket is arranged around a pipe for passing a refrigerant, a multi-tube cooling device having a configuration similar to that of the reactors 4a and 4b (see FIG. 2) in which the mixed gas passes inside a tube and the refrigerant passes around the tube, an air fin cooler, or the like.

[0051] The gas-liquid separator separates the condensed water generated when the mixed gas is cooled in the cooler from the mixed gas. The condensed water has the advantage that it can dissolve and remove unnecessary gas components (especially carbon dioxide) remaining in the mixed gas. The gas-liquid separator can be configured similarly to the gas-liquid separator of the microconstituent removing section 7, and can preferably be configured as a simple container. In this case, a filter that allows the passage of gas but prevents the passage of liquid may be disposed at the gas-liquid interface in the container. In this case, a liquid line may be connected to the bottom of the container, and a valve may be provided on the way. With this configuration, the condensed water stored in the container can be discharged (released) to the outside of the gas production apparatus 1 through the liquid line by opening the valve.

[0052] Furthermore, it is preferable to provide a drain trap downstream of the valve in the liquid line. This makes it possible to prevent carbon monoxide or hydrogen from being discharged outside the gas production apparatus 1, even if the valve malfunctions and carbon monoxide or hydrogen flows into the liquid line. Instead of or in addition to this drain trap, a valve malfunction detection function and redundancy measures in case of valve malfunction may be provided. The liquid line may be connected to the tank 30 described above so that the discharged condensed water can be reused.

[0053] The gas separator may be constructed using one or more of the following: a low-temperature separation type (cryogenic type) separator, a pressure swing adsorption (PSA) type separator, a membrane separation type separator, a temperature swing adsorption (TSA) type separator, a separator using a porous coordination polymer (PCP) that combines a metal ion (e.g., copper ion) with an organic ligand (e.g., 5-azidoisophthalic acid), and a separator that uses amine absorption. A valve may be provided between the gas-liquid separator and the gas separator in the gas line GL4. In this case, the processing speed of the mixed gas (the production speed of the generated gas) can be adjusted by adjusting the opening of the valve.

[0054] In this embodiment, the concentration of carbon monoxide contained in the mixed gas discharged from the gas-liquid separator is 75 to 90% by volume with respect to the entire mixed gas. Therefore, in fields where a product gas containing a relatively low concentration of carbon monoxide (75 to 90% by volume) can be used, the carbon monoxide can be directly supplied to the next process without being purified from the mixed gas, i.e., a gas separator can be omitted. Such fields include, for example, the field of synthesizing valuable substances (e.g., ethanol, etc.) from generated gas by fermentation with microorganisms (e.g., Clostridium, etc.), the field of producing steel using generated gas as a fuel or reducing agent, the field of manufacturing electric devices, and the field of synthesizing chemicals (phosgene, acetic acid, etc.) using carbon monoxide as a synthetic raw material.

[0055] On the other hand, in fields where it is necessary to utilize a product gas containing carbon monoxide at a relatively high concentration (over 90% by volume), carbon monoxide is purified from the mixed gas to obtain a product gas containing carbon monoxide at a high concentration. Such fields include, for example, a field in which the generated gas is used as a reducing agent (blast furnace), a field in which the generated gas is used as fuel to generate electricity by thermal power, a field in which the generated gas is used as a raw material to manufacture chemicals, and a field in which the generated gas is used as fuel for fuel cells.

[0056] Next, the method of using (functioning) the gas production system 100 will be described. [1] First, the gas line (flow path) is switched in the gas switching unit 8 to communicate the connection unit 2 with the reactor 4a, and the reducing gas supply unit 3 with the reactor 4b. [2] Next, in this state, the supply of exhaust gas from the furnace 20 via the connection part 2 is started. The exhaust gas supplied from the furnace 20 is usually at a high temperature of 50 to 300°C, but is cooled to 30 to 50°C before reaching the concentration adjusting section 5.

[0057] [3] Next, the exhaust gas passes through an oxygen removal device (concentration adjustment unit 5), which removes oxygen from the exhaust gas and increases the concentration of carbon dioxide contained in the exhaust gas. [4] The exhaust gas then passes through compression section 6, which increases the pressure of the exhaust gas. [5] Next, the exhaust gas passes through the fine component removal section 7. This removes condensed water generated when the exhaust gas is compressed in the compression section 6 and inactive components that reduce the activity of the reducing agent 4R from the exhaust gas.

[0058] [6] Next, the exhaust gas passes through the exhaust gas heating section 10, whereby the exhaust gas is heated. [7] Next, the exhaust gas is supplied to the reactor 4a. In the reactor 4a, the carbon dioxide in the exhaust gas is reduced to carbon monoxide by the reducing agent 4R. At this time, the reducing agent 4R is oxidized. The heating temperature of the exhaust gas in the above step [6] is preferably 300 to 700° C., more preferably 450 to 700° C., further preferably 600 to 700° C., and particularly preferably 650 to 700° C. If the heating temperature of the exhaust gas is set within the above range, for example, a sudden decrease in temperature of the reducing agent 4R due to an endothermic reaction when carbon dioxide is converted to carbon monoxide can be prevented or suppressed, and the reduction reaction of carbon dioxide in the reactor 4a can proceed more smoothly.

[0059] [8] In parallel with the above steps [2] to [7], water (reducing gas raw material) is supplied from the tank 30 to the hydrogen generation device (reducing gas supply unit 3), and hydrogen is generated from the water. [9] Next, the reducing gas containing hydrogen passes through the reducing gas heating section 11. This causes the reducing gas to be heated.

[10] Next, the reducing gas is supplied to the reactor 4b. In the reactor 4b, the reducing agent 4R in an oxidized state is reduced (regenerated) by the reducing gas (hydrogen). The heating temperature of the reducing gas in the above step [9] is preferably 300 to 700° C., more preferably 450 to 700° C., further preferably 600 to 700° C., and particularly preferably 650 to 700° C. If the heating temperature of the reducing gas is set within the above range, for example, a rapid temperature drop of the reducing agent 4R due to an endothermic reaction when reducing (regenerating) the reducing agent 4R in an oxidized state can be prevented or suppressed, so that the reduction reaction of the reducing agent 4R in the reactor 4b can proceed more smoothly.

[0060] Here, when the heating temperature of the exhaust gas by the exhaust gas heating unit 10 is X [°C] and the heating temperature of the reducing gas by the reducing gas heating unit 11 is Y [°C], |XY| (i.e., the absolute value of the difference between X and Y) preferably satisfies a relationship of 0 to 25, more preferably satisfies a relationship of 0 to 20, and further preferably satisfies a relationship of 0 to 15. In other words, the heating temperature X of the exhaust gas and the heating temperature Y of the reducing gas may be the same or slightly different. If X and Y are set so as to satisfy the above relationship, the conversion of carbon dioxide to carbon monoxide and the reduction of the reducing agent 4R by the reducing gas can be proceeded in a good balance. In addition, when the heating temperature X of the exhaust gas and the heating temperature Y of the reducing gas are made different from each other, the amount of heat required for the reduction reaction of the reducing agent 4R by the reducing gas tends to be larger than the amount of heat required for the reduction reaction of carbon dioxide by the reducing agent 4R. Therefore, it is preferable to set the heating temperature Y of the reducing gas higher than the heating temperature X of the exhaust gas.

[0061] In this embodiment, the timing of switching the gas lines in the gas switching unit 8 (i.e., the timing of switching between the exhaust gas and the reducing gas supplied to the reactors 4a, 4b) is preferably set as follows: Condition I: when a predetermined amount of exhaust gas is supplied to the reactor 4a or 4b; or Condition II: when the conversion efficiency of carbon dioxide to carbon monoxide falls below a predetermined value. In this way, the reactors 4a, 4b are switched before the conversion efficiency of carbon dioxide to carbon monoxide drops significantly, so that the concentration of carbon monoxide contained in the mixed gas can be increased and stabilized. To detect condition II, gas concentration sensors may be placed near the inlet and outlet ports of the reactors 4a and 4b, respectively. The conversion efficiency of carbon dioxide to carbon monoxide can be calculated based on the detection values ​​of the gas concentration sensors.

[0062] In addition, from the viewpoint of further stabilizing the concentration of carbon monoxide contained in the mixed gas, it is preferable to set the amount of exhaust gas supplied to the reactors 4a and 4b and the amount of reducing gas supplied to the reactors 4a and 4b as close as possible. Specifically, when the amount of exhaust gas supplied to the reactors 4a and 4b is P [mL / min] and the amount of reducing gas supplied to the reactors 4a and 4b is Q [mL / min], P / Q preferably satisfies a relationship of 0.9 to 2, and more preferably satisfies a relationship of 0.95 to 1.5. If the amount of exhaust gas supplied P is too large, depending on the amount of reducing agent 4R in the reactors 4a and 4b, the amount of carbon dioxide discharged from the reactors 4a and 4b tends to increase without being converted to carbon monoxide.

[0063] The predetermined amount in the above condition I is preferably an amount of 0.01 to 3 moles, and more preferably an amount of 0.1 to 2.5 moles, of carbon dioxide per mole of the metal element having the largest mass ratio in the reducing agent 4R. The predetermined value in the above condition II is preferably 50 to 100%, more preferably 60 to 100%, and even more preferably 70 to 100%. The upper limit of the predetermined value may be 95% or less, or may be 90% or less. In either case, it is possible to switch between the reactors 4a and 4b before the conversion efficiency of carbon dioxide to carbon monoxide drops drastically, and as a result, a mixed gas containing a high concentration of carbon monoxide can be stably obtained, and therefore a product gas containing a high concentration of carbon monoxide can also be produced.

[0064] The supply amount Q of the reducing gas (reducing substance) is preferably 0.1 to 3 moles of hydrogen per mole of the metal element having the largest mass ratio in the reducing agent 4R, and more preferably 0.15 to 2.5 moles. Even if the supply amount Q of the reducing gas is increased beyond the upper limit, no further increase in the effect of reducing the oxidized reducing agent 4R can be expected. On the other hand, if the supply amount Q of the reducing gas is too small, the reduction of the reducing agent 4R may be insufficient depending on the amount of hydrogen contained in the reducing gas. The pressure of the reducing gas supplied to the reactors 4a and 4b may be atmospheric pressure or pressurized (approximately the same as that of the exhaust gas).

[0065]

[11] Next, the gases that have passed through the reactors 4a and 4b are joined together to generate a mixed gas. At this point, the temperature of the mixed gas is usually 600 to 650°C. If the temperature of the mixed gas at this point is within the above range, it means that the temperature inside the reactors 4a and 4b is maintained at a sufficiently high temperature, and it can be determined that the conversion of carbon dioxide to carbon monoxide by the reducing agent 4R and the reduction of the reducing agent 4R by the reducing gas are proceeding efficiently.

[12] Next, the mixed gas is cooled to 100 to 300° C. before reaching the gas purification section 9.

[13] Next, the mixed gas passes through the gas purification unit 9. This removes, for example, the generated condensed water and carbon dioxide dissolved in the condensed water. As a result, carbon monoxide is purified from the mixed gas, and a product gas containing a high concentration of carbon monoxide is obtained. The temperature of the resulting produced gas is 20 to 50°C.

[14] Next, the produced gas is discharged from the produced gas discharge section 40 to the outside of the gas production apparatus 1 and is used for the next process.

[0066] <Configuration of the reducing agent heating unit (reducing agent temperature adjustment unit)> FIG. 4 is a schematic diagram showing a configuration of the reducing agent heating unit, and FIG. 5 is a schematic diagram showing another configuration of the reducing agent heating unit. The reducing agent heating section 12 shown in FIG. 4 includes a medium to be supplied to a space 43 defined by a plurality of tubes 41 and a housing 42 in the multi-tubular reactors 4a and 4b shown in FIG. 2, a transfer device 121 that transfers the medium to the space 43, and a heating device 122 that heats the medium.

[0067] The reducing agent heating section 12 of this configuration example includes a circulating medium line ML1 connected to each of the reactors 4a and 4b, and this medium line ML1 is filled with a medium. The medium line ML1 branches along the way, then connects to each of the reactors 4a and 4b, and then merges again to form a single line. A transfer device 121 and a heating device 122 are disposed along the combined medium line ML1. According to this configuration, the medium heated by the heating device 122 is supplied to the space 43 of the reactors 4a, 4b when circulating through the medium line ML1. This causes the reducing agent 4R to be indirectly heated via the tube 41. In addition, the heating temperatures of the reducing agent 4R in the two reactors 4a, 4b can be set to be approximately equal. The heating temperature of the reducing agent 4R is preferably 300 to 700° C., and more preferably 650 to 700° C. If the heating temperature is too high, the reducing agent 4R tends to deteriorate and become less active, although this depends on the type of metal oxide constituting the reducing agent 4R. On the other hand, if the heating temperature is too low, it tends to take a longer time to produce a product gas containing high concentrations of carbon monoxide.

[0068] The medium may be a gas, a liquid (including a viscous liquid), or the like. The heating device 122 can be composed of only an electric heater, or can be composed of an electric heater and a heat exchanger similar to that described in the exhaust gas heating section 10. According to the latter configuration, the heat of the high-temperature gas after passing through the reactors 4a, 4b is used to heat the medium by heat exchange before being supplied to the reactors 4a, 4b, thereby making it possible to effectively utilize heat. When a gas is used as the medium, the transfer device 121 can be configured with a blower, and when a liquid is used as the medium, the transfer device 121 can be configured with a pump. The reducing agent heating unit 12 may be configured with an electric heater instead of using a medium (heating gas). In this case, heating by the electric heater may be performed on the housing 42 of the reactors 4a and 4b, or may be performed separately on the tube 41 filled with the reducing agent 4R.

[0069] The reducing agent heating section 12 shown in FIG. 5 includes a non-circulating medium line ML2, and is configured to use the air (gas) as the medium. In this configuration example, a transfer device 121 (blower), a first heat exchanger 123, and a heating device 124 composed of an electric heater are arranged in this order from the atmospheric supply port side of the medium line ML2, and a second heat exchanger 125 is arranged on the atmospheric exhaust port side. It is preferable that the first heat exchanger 123 and the second heat exchanger 125 each have a similar configuration to the heat exchanger 102 . The first heat exchanger 123 exchanges heat between the gas (e.g., mixed gas) that has passed through the inside of the tubes 41 of the reactors 4a, 4b and the atmosphere before being supplied to the space 43 of the reactors 4a, 4b. On the other hand, the second heat exchanger 125 exchanges heat between the atmosphere that has passed through the space 43 of the reactors 4a, 4b and the exhaust gas before being supplied to the reactors 4a, 4b.

[0070] The heat of the high-temperature gas or the atmosphere (medium) after passing through the reactors 4a, 4b is used to heat the atmosphere (medium) or exhaust gas by heat exchange before being supplied to the reactors 4a, 4b, thereby enabling effective use of heat. The second heat exchanger 125 may be configured to exchange heat with the reducing gas before being supplied to the reactors 4a, 4b, instead of with the exhaust gas before being supplied to the reactors 4a, 4b, or may be configured to exchange heat with both the exhaust gas and the reducing gas before being supplied to the reactors 4a, 4b. In addition, according to the configuration example shown in FIG. 5, the temperature of the medium contacting the transport device 121 is lower than in the configuration example shown in FIG. 4, so there is an advantage that a relatively inexpensive transport device with low heat resistance can be used.

[0071] Here, if a combustion furnace or the like is used to heat the reactors 4a and 4b (reducing agent 4R), it becomes necessary to burn fuel to maintain the heating temperature (reaction temperature) of the reducing agent 4R, which generates carbon dioxide, which must be released into the atmosphere. In contrast, by configuring the reducing agent heating section 12 as shown in Figures 4 and 5, electricity (electrical energy) as renewable energy as described above can be used as the power source for the transfer device 121 and the heating devices 122 and 124, thereby reducing the burden on the environment. Another advantage is that the possibility of ignition of combustible gas present in the gas production apparatus 1 can be more reliably reduced.

[0072] The reducing agent heating unit may be configured to include an irradiation device that irradiates the reducing agent 4R with microwaves, instead of the configuration shown in FIG. 4 and FIG. According to the configuration in which the reducing agent 4R is heated by irradiating microwaves, the reducing agent 4R can be heated to a target temperature in a relatively short time. In addition, it is easy to heat not only the surface of the reducing agent 4R but also the center of the reducing agent 4R uniformly. Furthermore, it is easy to precisely control the heating temperature of the reducing agent 4R. Therefore, by using an irradiation device, it is possible to further increase the production efficiency of the generated gas. In addition, such an irradiation device can be made smaller than the configurations shown in Figures 4 and 5. In addition, in the case of microwave irradiation, only the vicinity of the surface of the reducing agent 4R can be locally (preferentially) raised to the desired temperature. Therefore, when the reaction proceeds at a high temperature (endothermic reaction), the efficiency is easily improved. In this case, it is necessary to input energy sufficient to raise the temperature only near the surface of the reducing agent 4R, and therefore energy efficiency is also improved.

[0073] Microwaves refer to electromagnetic waves with a frequency of 300 MHz to 300 GHz, and are classified into ultra-high frequency waves (UHF) with a frequency of 300 to 3000 MHz, centimeter waves (SHF) with a frequency of 3 to 30 GHz, millimeter waves (EHF) with a frequency of 30 to 300 GHz, and submillimeter waves (SHF) with a frequency of 300 to 3000 GHz. Among them, ultra-high frequency waves (UHF) are preferable as microwaves. By using ultra-high frequency waves (UHF), the reducing agent 4R can be heated to the desired temperature in a shorter time. When irradiating microwaves, appropriate measures to prevent leakage of radio waves in accordance with the Radio Law shall be taken.

[0074] Moreover, the microwave irradiation may be performed continuously or intermittently (in a pulsed manner). The present inventors have found that continuous microwave irradiation can further increase the efficiency of conversion of carbon dioxide to carbon monoxide and the efficiency of regeneration (reduction) of the reducing agent 4R by the reducing gas. Although the reason for this is not necessarily clear, it is believed that this is because the carbon dioxide contained in the exhaust gas supplied to the reactors 4a and 4b, and the hydrogen and reducing agent 4R contained in the reducing gas are activated by the microwaves that are continuously irradiated. On the other hand, when microwave irradiation is performed intermittently, it is sufficient to irradiate microwaves at a predetermined timing so as to compensate for only the amount of energy required for the endothermic reaction during the conversion of carbon dioxide to carbon monoxide and the regeneration (reduction) of the reducing agent 4R by the reducing gas, thereby improving energy efficiency.

[0075] In the case of heating by microwave irradiation, the heating temperature of the exhaust gas, the heating temperature of the reducing gas, and the heating temperature of the reducing agent 4R may be in the same range as above, or may be in a range different from above. For example, each of the heating temperatures can be set to 300 to 700°C. The irradiation device may be disposed inside or outside the reactors 4a and 4b. As described above, if the gas composition of the exhaust gas is made to be outside the explosion range by the concentration adjusting unit 5, it is possible to suitably prevent the exhaust gas from becoming an ignition source regardless of the microwave irradiation conditions. In addition, since the irradiation device uses electrical energy as its power source, there is also the advantage that this electrical energy can be easily switched to renewable energy.

[0076] As described above, when the reaction by the reducing agent 4R is an exothermic reaction, the reducing agent temperature adjustment unit can be configured as a reducing agent cooling unit. In this case, for example, in the configuration shown in Fig. 4 and Fig. 5, the first heat exchanger 123 and the second heat exchanger 125 may be omitted, and the heating devices 122 and 124 may be changed to cooling devices. Examples of the cooling device include a jacket type cooling device and a multi-tube type cooling device. In this case, too, it is preferable to set the cooling temperature of the reducing agent 4R (temperature after temperature adjustment) to the same range as described above.

[0077] <Configuration near the connection part> FIG. 6 is a schematic diagram showing the configuration in the vicinity of the connection part (raw material gas supply part) between the gas production apparatus of the present invention and the furnace. As shown in Fig. 6, the furnace 20 is provided with a chimney 21 that discharges exhaust gas into the atmosphere. One end of a gas line 23 is connected to a branching portion 22 midway along the height of the chimney 21. The other end of the gas line 23 is connected to a connection portion 2 of the gas production device 1.

[0078] 6, a cooling section 13 is provided between the connection section 2 and the concentration adjusting section 5. The cooling section 13 includes a cooling device 131 and a container 132 connected to the cooling device 131. The cooling device 131 can be configured by a jacket-type cooling device, a multi-tube type cooling device, or the like as described above. The exhaust gas supplied from the furnace 20 contains water vapor as well as oxidizing gas components (SO x Since the oxidizing gas also contains other acids (HCl, etc.), it is preferable to condense the water vapor together with the oxidizing gas components by cooling in the cooling unit 13 and remove the condensed water (acidic aqueous solution) in which the oxidizing gas components are dissolved. This makes it possible to suitably prevent corrosion of the piping that constitutes the gas line GL1. In this configuration example, an acidic aqueous solution is generated by cooling the exhaust gas in a cooling device 131, and this acidic aqueous solution is stored in a container 132 and separated from the exhaust gas. In addition, a filter that allows the passage of gas but prevents the passage of liquid may be disposed at the gas-liquid interface in the container 132. In such a configuration, the distance (L1 in FIG. 6) between the branching portion 22 and the cooling device 131 is not particularly limited, but is preferably 10 m or less, and more preferably 1 to 5 m. By setting the distance L1 in the above range, it is possible to prevent the generation of condensed water (acidic aqueous solution) in which acid gas is dissolved, in unintended locations of the gas line GL1, and more reliably prevent corrosion of the piping that constitutes the gas line GL1.

[0079] Furthermore, when the gas production system 100 is installed in a cold region, for example, depending on the distance L2 between the furnace 20 and the gas production device 1, condensed water may be generated midway through the gas line 23 and may even freeze. This may cause the piping that constitutes the gas line 23 to break. Therefore, in order to prevent such trouble, it is preferable to heat the exhaust gas in the gas line 23. The heating temperature may be any temperature at which freezing does not occur, but is preferably equal to or higher than the acid dew point temperature (e.g., 120° C.), and more preferably 120 to 150° C. This makes it possible to prevent damage to the pipes constituting the gas line 23, while also suitably preventing corrosion of the pipes due to the generation of condensed water in which acid gas is dissolved. In order to heat the exhaust gas in the gas line 23, for example, an electric heating wire (heater) may be wound around the piping constituting the gas line 23. For the purpose of corrosion resistance, a resin-lined pipe made of a corrosion-resistant resin material (for example, a fluororesin material) may be used instead of using a heater. In this configuration example, the container 132 may be omitted if necessary.

[0080] In the above embodiment, exhaust gas is used as an example of the raw material gas, but as described above, the raw material gas is not limited to exhaust gas as long as it is a gas containing carbon dioxide. Therefore, in the above embodiment, various treatment conditions for the exhaust gas (including the pressure of compression by the compression section 6, the heating temperature before supplying to the reactors 4a and 4b, the amount of supply to the reactors 4a and 4b, etc.) can be similarly applied to other raw material gases.

[0081] By using the gas production apparatus 1 and the gas production system 100 as described above, a product gas containing carbon monoxide can be produced from a raw material gas containing carbon dioxide. <Gas production method> The gas production method of the present embodiment is a method of producing a product gas containing carbon monoxide by contacting the exhaust gas (raw material gas) with the reducing agent 4R, and includes the steps of: I: preparing a plurality of reactors 4a, 4b each having the reducing agent 4R disposed therein, and exhaust gas; II: bringing the exhaust gas into contact with the reducing agent 4R in each of the reactors 4a, 4b to convert carbon dioxide into carbon monoxide; and III: recovering the gas that has passed through the reactors 4a, 4b as it is, or purifying carbon monoxide from the gas that has passed through the reactors 4a, 4b, as a product gas. Prior to supplying the exhaust gas to the reactors 4a, 4b, the exhaust gas before being supplied to the reactors 4a, 4b is contacted with a substance capable of capturing a component contained in the exhaust gas and that reduces the activity of the reducing agent 4R upon contact with the reducing agent 4R.

[0082] <Product> The generated gas produced using the gas production apparatus 1 and the gas production system 100 generally has a carbon monoxide concentration of 60 vol % or more, preferably 75 vol % or more, and more preferably 90 vol % or more. Furthermore, the generated gas as described above can be used in fields such as the synthesis of valuable substances (e.g., ethanol, etc.) by fermentation with microorganisms (e.g., Clostridium, etc.), the production of steel using it as a fuel or reducing agent, the production of electric devices, the production of chemicals (phosgene, acetic acid, etc.) using carbon monoxide as a synthetic raw material, the use of it as a reducing agent (blast furnaces), the use of it as fuel for thermal power generation, and the use of it as fuel in fuel cells, etc.

[0083] In the reactors 4a and 4b shown in Fig. 2, when exhaust gas comes into contact with the reducing agent 4R, carbon monoxide is generated by the reduction reaction of carbon dioxide, and at least a part of the oxygen atoms separated from the carbon dioxide is captured by the reducing agent 4R, and then, when a reducing gas comes into contact with the reducing agent 4R, it is handed over to hydrogen (reducing substance), and water (oxide of the reducing substance) is generated. That is, in the reactors 4a and 4b shown in Fig. 2, at least a part of the oxygen atoms can be separated within the system (reaction field) of the reduction reaction of carbon dioxide. A reactor capable of separating at least a portion of the oxygen atoms in the carbon dioxide reduction reaction system may have a configuration shown in FIG.

[0084] The reactors 4a and 4b shown in Figs. 1 and 2 are configured to divide the reverse water-gas shift reaction into two reactions, a conversion reaction of carbon dioxide to carbon monoxide and a reduction reaction by hydrogen (a reducing substance), and to utilize a method of bridging these reactions with the reducing agent 4R (the so-called chemical looping method). The reactor in the present invention may also be configured to convert carbon dioxide into carbon monoxide by electrolysis. Such a configuration (second configuration example) will be described below.

[0085] The reactor 4c of the second configuration example shown in FIG. 7 is a reaction device that electrochemically carries out a reduction reaction of carbon dioxide, and is also called a reaction cell, an electrolytic cell, or an electrochemical cell. The reactor 4 c includes a housing 42 , a cathode 45 , an anode 46 and a solid electrolyte layer 47 provided within the housing 42 , and a power source 48 electrically connected to the cathode 45 and the anode 46 . In this configuration, the space within the housing 42 is divided into left and right spaces by a laminate of the cathode (reduced body) 45, the anode 46, and the solid electrolyte layer 47. The housing 42 is provided with a cathode side inlet port 421a, a cathode side outlet port 421b, an anode side inlet port 422a, and an anode side outlet port 422b. The cathode side inlet port 421a and the cathode side outlet port 421b communicate with a cathode chamber in a left space within the housing 42, and the anode side inlet port 422a and the anode side outlet port 422b communicate with an anode chamber in a right space within the housing 42.

[0086] The cathode 45 and the anode 46 are each composed of a conductive support and a catalyst supported on the support. The support may be made of a carbon material such as, for example, carbon fiber fabric (carbon cloth, carbon felt, etc.) or carbon paper. Examples of the catalyst include platinum group metals such as platinum, ruthenium, rhodium, palladium, osmium, and iridium; transition metals such as gold; alloys of these metals; and alloys of these metals with other metals. The solid electrolyte layer 47 can be made of, for example, a fluorine-based polymer membrane having a sulfonic acid group (such as Nafion (registered trademark)), a sulfo-based ion exchange resin membrane, or the like. It is preferable to use a power supply that generates electricity as renewable energy as the power supply 48. This can further improve the energy efficiency in the production of the generated gas.

[0087] In the reactor 4c, when exhaust gas (carbon dioxide and water vapor) is supplied from the cathode side inlet port 421a, carbon monoxide and hydrogen are produced by a reduction reaction of carbon dioxide and water due to the action of the catalyst and electrons supplied from the power source 48, and oxygen ions are also produced. The carbon monoxide and hydrogen are discharged from the cathode side outlet port 421b to a gas line (gas line GL4), and the oxygen ions diffuse within the solid electrolyte layer 47 toward the anode 46. The oxygen ions that reach the anode 46 are converted to oxygen by having their electrons stolen, and are discharged from the anode side outlet port 422b. In this manner, at least a portion of the oxygen atoms released from carbon dioxide at the cathode 45 are separated as oxygen ions within the reduction reaction system (reaction field) and converted to oxygen at the anode .

[0088] The reactor in the present invention may be a reactor having a configuration in which at least a part of the oxygen atoms released from carbon dioxide by the reduction reaction is not separated within the reduction reaction system. Such a reactor includes a device that utilizes the reverse water-gas shift reaction in which carbon dioxide and hydrogen are simultaneously contacted with a reducing agent 4R to convert carbon dioxide to carbon monoxide and hydrogen (a reducing substance) to water (an oxide of the reducing substance). In this reactor, at least a portion of the oxygen atoms released from the carbon dioxide reacts with hydrogen to produce water without being separated from the reduction reaction system (reaction field). However, if a reactor capable of separating at least a portion of the oxygen atoms released from carbon dioxide within the reduction reaction system (reaction field) is used as described above, it becomes difficult for the reaction products, carbon monoxide and water, to coexist within the system, making it possible to prevent or suppress a decrease in the conversion efficiency of carbon dioxide to carbon monoxide due to constraints of chemical equilibrium.

[0089] In the above-described gas production system 100 (gas production apparatus 1), the gases passing through the reactors 4a and 4b are joined together immediately after passing through the reactors 4a and 4b, but various treatments may be performed before joining together. That is, at least one type of treatment device can be provided midway along the branch gas lines GL4a and GL4b for any purpose. Next, the gas production system 100 having such a configuration will be described. FIG. 8 is a schematic diagram showing another embodiment of the gas production system of the present invention, and FIG. 9 is a cross-sectional view showing a schematic configuration of the purifier of FIG. The gas production system 100 shown in FIG. 8 will be described below, focusing on the differences from the gas production system 100 shown in FIG. 1, and a description of the similar points will be omitted. 8 further includes purifiers 14a, 14b provided in the branch gas lines GL4a, GL4b. That is, the purifiers 14a, 14b are connected downstream of the corresponding reactors 4a, 4b, and the gases that have passed through the reactors 4a, 4b and the purifiers 14a, 14b in sequence are joined at a gas junction J4.

[0090] 9, each of the purifiers 14a, 14b is configured as a multi-tube type purification device including a plurality of separation tubes 141 and a housing (purifier body) 142 that contains the plurality of separation tubes 141. According to such a multi-tube type purification device, it is possible to ensure a sufficient opportunity for the gas that has passed through the reactors 4a, 4b to come into contact with the separation tubes 141. Each of the purifiers 14a, 14b is preferably configured to be capable of at least one of separating water (oxide of the reducing substance) and hydrogen (reducing substance) generated by contact with the reducing agent 4R, and separating carbon monoxide and carbon dioxide. In particular, the separation tube 141 is preferably configured to allow water (water vapor) or carbon monoxide to pass through its wall and separate it from hydrogen or carbon dioxide.

[0091] In this embodiment, the water and carbon monoxide that permeate the separation tube 141 are discharged from the purifiers 14a and 14b to the branch gas lines GL4a and GL4b. On the other hand, the reducing gas (unreacted hydrogen) and exhaust gas (unreacted carbon dioxide) that pass through the separation tube 141 are discharged to the gas lines GL14a and GL14b connected to the housing 142 (space 143). These gas lines GL14a and GL14b may be connected to the middle of the gas line GL1 and the gas line GL2, respectively, so that unreacted hydrogen and carbon dioxide can be reused. The gas discharged to the branch gas lines GL4a and GL4b may contain gas components other than water or carbon monoxide, and the gas discharged to the gas lines GL14a and GL14b may contain gas components other than hydrogen or carbon dioxide.

[0092] The separation of carbon monoxide and carbon dioxide, and the separation of water and hydrogen can also be achieved by cooling the gas discharged from each of the reactors 4a and 4b by utilizing the difference in condensation (liquefaction) temperature. However, in this case, when the separated gas components are used at a high temperature downstream of the reactors 4a and 4b (for example, when used in the heat exchanger 102), they need to be heated again, resulting in a waste of thermal energy. In contrast, the purifiers 14a and 14b can perform the separation operation of the gas components at a high temperature (for example, 200 to 500°C), so that the temperature of the separated gas components is unlikely to decrease, which can contribute to a reduction in thermal energy in the entire production of the generated gas. In order to more reliably prevent a decrease in the temperature of the gas components after separation by the refiners 14a and 14b, a heating device for heating the separation tube 141 (for example, an irradiation device for irradiating microwaves as described above) may be provided.

[0093] As described above, gas at a relatively high temperature is discharged from each of the reactors 4a and 4b. Therefore, it is preferable that the separation tube 141 has heat resistance. This can prevent the separation tube 141 from being altered or deteriorated. The separation tube 141 is preferably made of a metal, an inorganic oxide, or a metal organic framework (MOF). In this case, it is easy to impart excellent heat resistance to the separation tube 161. Here, examples of the metal include titanium, aluminum, copper, nickel, chromium, cobalt, and alloys containing these. Examples of the inorganic oxide include silica and zeolite. Examples of the metal organic framework include a structure of zinc nitrate hydrate and terephthalic acid dianion, and a structure of copper nitrate hydrate and trimesic acid trianion. When a metal is used, the separation tube 141 is preferably made of a porous material with a porosity of 80% or more.

[0094] Separation tube 141 is preferably made of a porous body having continuous pores (pores penetrating the tube wall) in which adjacent pores communicate with each other. Separation tube 141 having such a configuration can increase the permeability of water or carbon monoxide, and more smoothly and reliably separate water from hydrogen and / or carbon monoxide from carbon dioxide. The porosity of separation tube 141 is not particularly limited, but is preferably 5 to 95%, more preferably 10 to 90%, and even more preferably 20 to 60%. This makes it possible to prevent the mechanical strength of separation tube 141 from decreasing excessively, while maintaining a sufficiently high permeability to water or carbon monoxide. The shape of the separation tube 141 is not particularly limited, and examples thereof include a cylindrical shape, a rectangular shape, and a rectangular tube shape such as a hexagon.

[0095] From the viewpoint of improving the handleability of the gas after merging at the gas junction J4 (preventing ignition) and maintaining high production efficiency of the generated gas, it is effective to remove unreacted hydrogen. That is, as shown in FIG. 9, it is preferable to configure the system so that water is transferred to a space 143 in a housing 142 via a separation tube 141 from hydrogen (H2) and water (H2O) that have passed through reactors 4a and 4b. In this case, the average pore size of the separation cylinder 141 is preferably 600 pm or less, and more preferably 400 to 500 pm, thereby making it possible to further improve the efficiency of separation of water and hydrogen. The space 143 within the housing 142 may be depressurized or a carrier gas (sweep gas) may be passed through the space 143. Examples of the carrier gas include inert gases such as helium and argon.

[0096] Moreover, separation tube 141 is preferably hydrophilic. If separation tube 141 has hydrophilic properties, the affinity of water to separation tube 141 increases, and water can easily pass through separation tube 141 more smoothly. Methods for imparting hydrophilicity to separation tube 141 include a method of improving the polarity of separation tube 141 by changing the ratio of metal elements in the inorganic oxide (e.g., increasing the Al / Si ratio), a method of coating separation tube 141 with a hydrophilic polymer, a method of treating separation tube 141 with a coupling agent having a hydrophilic group (polar group), a method of subjecting separation tube 141 to plasma treatment, corona discharge treatment, etc. Furthermore, the surface potential of the separation cylinder 141 may be adjusted to control its affinity for water.

[0097] On the other hand, when separation of carbon monoxide and carbon dioxide is given priority in separation column 141, or when separation of water and hydrogen and separation of carbon monoxide and carbon dioxide are performed simultaneously, the constituent material, porosity, average pore size, degree of hydrophilicity or hydrophobicity, surface potential, etc. of separation column 141 can be set in an appropriate combination. The refiner may be provided between the gas junction J4 and the gas refinement section 9 in the gas line GL4. Furthermore, when the purifiers 14a and 14b are provided, the gas purifying section 9 may be omitted.

[0098] Although the gas production apparatus, the gas production system, and the gas production method of the present invention have been described above, the present invention is not limited to these. For example, the gas production apparatus and gas production system of the present invention may each have any other additional configuration compared to the above-mentioned embodiments, may be replaced with any configuration that performs a similar function, or some configurations may be omitted. Moreover, in the gas production method of the present invention, a step for any purpose may be added to the above embodiment.

[0099] The reactors 4a and 4b may be configured as moving bed reactors instead of fixed bed reactors. In this case, the two reactors 4a and 4b are connected to each other at the upper and lower parts, and the reducing agent 4R can be moved (circulated) between the reactors 4a and 4b. In this case, the gas line GL1 is connected to the inlet port of one of the reactors 4a, 4b without branching, and the gas line GL2 is also connected to the inlet port of the other of the reactors 4a, 4b without branching. In this case, one of the reactors 4a and 4b is a countercurrent vertical reactor, and the other is a parallel vertical reactor. Both of the reactors 4a and 4b may be cross-flow reactors.

[0100] In the above embodiment, a gas containing hydrogen has been described as a representative reducing gas, but the reducing gas may also be a gas containing at least one selected from hydrocarbons (e.g., methane, ethane, acetylene, etc.) and ammonia as a reducing substance instead of or in addition to hydrogen. In the above embodiment, the heat exchanger is described as being configured to exchange heat between the exhaust gas (raw material gas), the reducing gas or the heating medium before being supplied to the reactor and the mixed gas. However, a heat exchanger configured to exchange heat with the gas discharged from each reactor and before being made into the mixed gas may be employed.

[0101] Also, the gas junction J4 may be omitted, and the branch gas lines GL4a and GL4b may be independent gas lines. In this case, the gas (water or carbon monoxide) after passing through each of the reactors 4a and 4b is transferred through the branch gas lines GL4a and GL4b that are independent of each other. For example, the gas containing water (water vapor) is subjected to disposal treatment or conversion treatment to the tank 30, and the gas containing carbon monoxide is subjected to purification treatment as necessary and then subjected to subsequent treatment. With this configuration, the gases after passing through each of the reactors 4a and 4b can be treated independently of each other. [Explanation of symbols]

[0102] 100...Gas production system 1. Gas production equipment 2. Connection 3…Reducing gas supply section 4. Reaction section 4a, 4b...Reactor 41: tube body, 42: housing, 43: space, 44: partition wall, 4R: reducing agent 4c…Reactor 421a...cathode side inlet port, 421b...cathode side outlet port, 422a...anode side inlet port, 422b...anode side outlet port, 45: cathode, 46: anode, 47: solid electrolyte layer, 48: power source 5...Density adjustment section 6…Compression section 7…Fine component removal section 8…Gas switching section 9. Gas purification section 10…Exhaust gas heating section 101...Electric heater, 102...Heat exchanger 11...Reducing gas heating section 12...Reducing agent heating section 121...transfer device, 122...heating device, 123...first heat exchanger, 124...electric heater, 125…Second heat exchanger 13…Cooling section 131...Cooling device, 132...Container 14a, 14b...purifier 141: Separation tube, 142: Housing, 143: Space 20...Furnace 21: Chimney; 22: Branch; 23: Gas line 30…Tank 40...Produced gas exhaust section GL1…Gas line GL2…Gas line GL3a, GL3b...Gas line GL4…Gas line GL4a, GL4b: Branch gas lines, J4: Gas junction GL14a, GL14b...Gas line L1…Separation distance L2…Separation distance

Claims

1. A gas production apparatus for producing a product gas containing carbon monoxide by contacting a raw material gas containing carbon dioxide with a solid reductant that reduces the carbon dioxide, comprising: a raw material gas supply unit for supplying the raw material gas; A reaction section including a plurality of reactors that store a reducing agent that reduces the carbon dioxide as the reductant; a reducing gas supply unit that supplies a reducing gas containing a reducing substance that reduces the reducing agent that has been oxidized by contact with the carbon dioxide; a protective device provided between the raw material gas supply unit and the reactor, the protective device including a substance capable of capturing a component contained in the raw material gas and that reduces activity of the reductant upon contact with the reductant; each of the reactors is connected to at least one of the raw material gas supply unit and the reducing gas supply unit, and is capable of switching between the raw material gas and the reducing gas supplied to each of the reactors or of moving the reducing agent between the reactors; A gas producing apparatus characterized in that it is configured to merge the gas containing carbon monoxide after passing through the reactor and the gas containing an oxide of the reduced substance after passing through the reactor.

2. 2. The gas production apparatus according to claim 1, wherein the component is at least one selected from the group consisting of sulfur, mercury, a sulfur compound, a halogen compound, an organic silicone, an organic phosphorus, and an organic metal compound.

3. A gas manufacturing apparatus as described in claim 1 or 2, wherein the reducing agent includes a metal oxide.

4. The gas manufacturing apparatus according to claim 3, wherein the metal oxide contains at least one metal element selected from the group consisting of metal elements belonging to groups 3 to 12.

5. The apparatus further includes a compression section for increasing a pressure of the raw material gas, and a raw material gas heating section for heating the raw material gas that has passed through the compression section and before being supplied to the reactor, 5. The gas production apparatus according to claim 1, wherein the protective device is provided between the compression section and the raw material gas heating section.

6. a raw material gas generating unit for generating a raw material gas containing carbon dioxide; The gas production apparatus according to any one of claims 1 to 5, The gas production system is characterized in that the gas production apparatus is connected to the raw material gas generation unit via the raw material gas supply unit.

7. A gas production method for producing a product gas containing carbon monoxide by contacting a raw material gas containing carbon dioxide with a solid reductant that reduces the carbon dioxide, comprising the steps of: preparing a plurality of reactors for storing a reducing agent that reduces the carbon dioxide as the reductant, the raw material gas, and a reducing gas containing a reducing substance that reduces the reducing agent that has been oxidized by contact with the carbon dioxide; by switching the reactors to which the raw material gas and the reducing gas are supplied, the raw material gas and the reducing gas are alternately brought into contact with the reducing agent in each of the reactors to convert the carbon dioxide into carbon monoxide, and then the oxidized reducing agent is reduced; contacting the raw material gas before being supplied to the reactor with a substance capable of capturing a component contained in the raw material gas, the component decreasing activity of the reducing agent upon contact with the reducing agent; The gas containing carbon monoxide after passing through the reactor and the gas containing oxides of the reduced material after passing through the reactor are combined to generate a mixed gas; A gas production method, comprising recovering the mixed gas as the product gas as it is or by purifying the carbon monoxide from the mixed gas.

8. The gas production method according to claim 7, wherein the reducing agent comprises a metal oxide.

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