WO2023100834A1 - Gas production apparatus - Google Patents

Abstract

[Problem] To provide a gas production apparatus capable of efficiently producing valuable carbon by using an oxidizing gas that contains carbon dioxide and a reducing gas that contains a reducing substance. [Solution] One aspect of the present invention provides a gas production apparatus. This gas production apparatus has a plurality of reactors. Each reactor accommodates a reducing agent, and is configured to be capable of switching between supplying an oxidizing gas that contains carbon dioxide and supplying a reducing gas that contains a reducing substance. The reducing agent contains a metal and/or metal oxide which generates valuable carbon by reducing carbon dioxide, said reducing agent being brought into an oxidized state through contact with the carbon dioxide and then reduced through contact with the reducing substance. Some or all of the oxidizing gas and/or the reducing gas that has traversed a reactor is returned to the upstream side of the same reactor.

Description

gas production equipment

The present invention relates to gas production equipment.

In recent years, the atmospheric concentration of carbon dioxide (CO ₂ ), which is a kind of greenhouse gas, continues to rise. Rising concentrations of carbon dioxide in the atmosphere contribute to global warming. Therefore, it is important to recover the carbon dioxide released into the atmosphere, and if the recovered carbon dioxide can be converted into carbon valuables and reused, a carbon recycling society can be realized.
Also, as a global measure, as stated in the Kyoto Protocol of the United Nations Framework Convention on Climate Change, the reduction rate of carbon dioxide, which causes global warming, in developed countries based on 1990 as a standard It is stipulated that we will jointly achieve the reduction target value within the commitment period.

In order to achieve the reduction target, exhaust gas containing carbon dioxide generated from steel mills, smelters or thermal power plants is also targeted, and various technological improvements have been made regarding the reduction of carbon dioxide in these industries. ing. One example of such technology is _CO2 capture and storage (CCS). However, this technique has a physical limit of storage and is not a fundamental solution.
For example, Patent Literature 1 discloses a carbon dioxide reduction system comprising a chemical looping reactor. This chemical looping type reactor has two reactors filled with a metal oxide catalyst, one reactor for the first reaction of reducing carbon dioxide to carbon monoxide, and the other reactor for the reduction of carbon dioxide to carbon monoxide. A second reaction that oxidizes hydrogen to water takes place in the vessel.

WO2019/163968

However, there is still room for further improvement in industrially producing carbon monoxide (a carbon valuable product) from carbon dioxide more efficiently.
In view of the above circumstances, the present invention provides a gas production apparatus capable of efficiently producing carbon valuables by using an oxidizing gas containing carbon dioxide and a reducing gas containing a reducing substance.

According to one aspect of the present invention, a gas production device is provided. This gas production device has a plurality of reactors. Each reactor accommodates a reducing agent and is configured to be capable of switching between an oxidizing gas containing carbon dioxide and a reducing gas containing a reducing substance. The reducing agent contains at least one of a metal and a metal oxide that generate a carbon value by reducing carbon dioxide, is oxidized by contact with carbon dioxide, and is reduced by contact with a reducing substance. . A part or all of at least one of the oxidizing gas and the reducing gas that have passed through each reactor is again returned to the upstream side of the same reactor.

According to this aspect, it is possible to efficiently produce carbon valuables by using an oxidizing gas containing carbon dioxide and a reducing gas containing a reducing substance.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which shows the whole structure of the gas manufacturing system using the gas manufacturing apparatus of this invention. It is a schematic diagram showing the configuration of the reaction section of the first embodiment. It is a schematic diagram showing the configuration of the reaction section of the second embodiment. It is a schematic diagram showing the configuration of the reaction section of the third embodiment. It is a schematic diagram showing the configuration of the reaction section of the fourth embodiment. FIG. 11 is a schematic diagram showing the configuration of a reaction section of a fifth embodiment;

BEST MODE FOR CARRYING OUT THE INVENTION A gas production apparatus of the present invention will be described in detail below based on preferred embodiments shown in the accompanying drawings.
First, the overall configuration of the gas production system will be described.
<First embodiment>
FIG. 1 is a schematic diagram showing the overall configuration of a gas production system using the gas production apparatus of the present invention. FIG. 2 is a schematic diagram showing the configuration of the reaction section of the first embodiment.
A gas production system 100 shown in FIG. 1 includes a furnace 20 that generates exhaust gas (oxidizing gas) containing carbon dioxide, and a gas production device 1 that is connected to the furnace 20 via a connector 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 simply referred to as the "downstream side".

The furnace 20 is not particularly limited, but is, for example, a furnace attached to an ironworks, a refinery, or a thermal power plant, preferably a combustion furnace, a blast furnace, a converter, or the like. In the furnace 20, exhaust gas is produced (generated) during combustion, melting, refining, and the like of the contents.
In the case of a combustion furnace (incinerator) in a garbage incineration plant, the contents (waste) include, for example, plastic waste, garbage, municipal waste (MSW), waste tires, biomass waste, household waste (bedding , paper), building materials, and the like. In addition, these wastes may contain 1 type independently, or may contain 2 or more types.

Exhaust gases typically contain, in addition to carbon dioxide, other gas components such as nitrogen, oxygen, carbon monoxide, water vapor, methane, and the like. 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% by volume or more, more preferably 5% by volume or more.
Exhaust gas from a combustion furnace in a garbage incineration plant contains 5-15% by volume of carbon dioxide, 60-70% by volume of nitrogen, 5-10% by volume of oxygen, and 15-25% by volume of water vapor.

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% by volume of carbon dioxide, 55 to 60% by volume of nitrogen, and 25 to 30% by volume of carbon monoxide. , containing 1 to 5% by volume of hydrogen.
In addition, the exhaust gas from the converter (converter gas) is a gas generated when steel is produced in the converter, and contains 15 to 20 volume% carbon dioxide, 50 to 60 volume% carbon monoxide, and nitrogen. It contains 15 to 25% by volume and 1 to 5% by volume of hydrogen.
The oxidizing gas is not limited to the exhaust gas, and a pure gas containing 100% by volume of carbon dioxide may be used.

However, if the exhaust gas is used as the oxidizing gas, the carbon dioxide that has conventionally been discharged into the atmosphere can be effectively used, and the burden on the environment can be reduced. Among these, from the viewpoint of carbon circulation, exhaust gas containing carbon dioxide generated in ironworks or smelters is preferable.
In addition, as the blast furnace gas and the converter gas, the untreated gas discharged from the furnace may be used as it is. good. The untreated blast furnace gas and the converter gas have gas compositions as described above, and the treated gas has a gas composition close to that shown for the exhaust gas from the combustion furnace. In this specification, all of the above gases (the gases before being supplied to the gas production apparatus 1) are called exhaust gas.

In the gas production apparatus 1, the exhaust gas (oxidizing gas containing carbon dioxide) discharged from the furnace 20 and supplied via the connecting portion 2 is brought into contact with a reducing agent 4R that reduces the carbon dioxide contained in the exhaust gas. , to produce a product gas (syngas) containing carbon monoxide.
In this specification, carbon monoxide will be described as a representative example of the carbon valuables. However, carbon valuables are not limited to carbon monoxide, and include, for example, methane, methanol and the like, and they may be used alone or in combination of two or more. Depending on the type of reducing agent, which will be described later, the type of carbon valuables produced will differ.

The gas production apparatus 1 mainly includes a connection portion 2, a reducing gas supply portion 3, a reaction portion 4 having two reactors 4a and 4b, and a gas line GL1 connecting the connection portion 2 and the reaction portion 4. , a gas line GL2 connecting the reducing gas supply unit 3 and the reaction unit 4, and a gas line GL4 connected to the reaction unit 4.
In this embodiment, the connecting portion 2 constitutes an exhaust gas supply portion (oxidizing gas supply portion) that supplies the exhaust gas to the reaction portion 4 .
In addition, if necessary, a pump for transferring gas may be arranged at a predetermined position in the middle of the gas line GL1, the gas line GL2, and the gas line GL4. For example, when the pressure of the exhaust gas is adjusted to be relatively low in the compression unit 6, which will be described later, the gas can be smoothly transferred within the gas production apparatus 1 by arranging a pump.

Gas line GL1 is connected to connecting portion 2 at one end thereof. On the other hand, the other end of the gas line GL1, as shown in FIG. It is connected.
With such a configuration, the exhaust gas supplied from the furnace 20 through the connecting portion 2 passes through the gas line GL1 and is supplied to the reactors 4a and 4b.
The gas switching unit 8 can be configured to include, for example, a branch gas line and a channel opening/closing mechanism such as a valve provided in the middle of the branch gas line.

Each of the reactors 4a and 4b, as shown in FIG. 2, is a multi-tubular reactor comprising a plurality of tubular bodies 41 each filled with (accommodated) a reducing agent 4R and a housing 42 accommodating the plurality of tubular bodies 41. It consists of an apparatus (fixed bed reactor). According to such a multi-tubular reactor, it is possible to ensure sufficient opportunities for contact between the reducing agent 4R and the exhaust gas and reducing gas. As a result, the production efficiency of the product gas can be enhanced.
The reducing agent 4R of the present embodiment is preferably, for example, in the form of particles (granules), scales, pellets, or the like. With such a shape of the reducing agent 4R, the filling efficiency into the tubular body 41 can be enhanced, and the contact area with the gas supplied into the tubular body 41 can be further increased.

When the reducing agent 4R is particulate, its volume average particle diameter is not particularly limited, but is preferably 1 to 50 mm, 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, the 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 tumbling granulation because the sphericity is increased.

Also, the reducing agent 4R may be supported on a carrier.
The constituent material of the carrier may be any material as long as it is difficult to denature due to contact with exhaust gas (oxidizing gas), reaction conditions, etc. Examples include carbon materials (graphite, graphene, etc.), carbides such as Mo ₂ C, zeolite, montmorillonite, Examples include oxides such as ZrO ₂ , TiO ₂ , V ₂ O ₅ , MgO, CeO ₂ , Al ₂ O ₃ and SiO ₂ and composite oxides containing these.

Among these, zeolite, montmorillonite, ZrO ₂ , TiO ₂ , V ₂ O ₅ , MgO, Al ₂ O ₃ , SiO ₂ and composite oxides containing these are preferable as the constituent material of the carrier. A carrier composed of such a material is preferable in that it does not adversely affect the reaction of the reducing agent 4R and is excellent in the ability to support the reducing agent 4R. Here, the carrier does not participate in the reaction of the reducing agent 4R and merely supports (holds) the reducing agent 4R.
An example of such a form includes a configuration in which at least part of the surface of the carrier is coated with the reducing agent 4R.

The reducing agent 4R contains at least one of metal and metal oxide (oxygen carrier). At least one of the metal and metal oxide is not particularly limited as long as it can reduce carbon dioxide, but preferably contains at least one selected from metal elements belonging to Groups 3 to 12. It is more preferable to contain at least one selected from metal elements belonging to Groups 4 to 12, and at least one of titanium, vanadium, iron, copper, zinc, nickel, manganese, chromium and cerium. It is more preferable to contain iron, and metal oxides or composite metal oxides containing iron are particularly preferable. These metal oxides are useful because they are particularly efficient in converting carbon dioxide to carbon monoxide.
Here, the metal includes an elemental metal consisting of only one of the above metal elements and an alloy consisting of two or more of the above metal elements.

In particular, iron oxide, cerium oxide, etc. are suitable as metal oxides that convert carbon dioxide into carbon monoxide. As the metal oxide that converts carbon dioxide to methane, for example, zirconia, alumina, titania, silica, etc. that support or contain at least one of nickel and ruthenium are suitable. As the metal oxide that converts carbon dioxide into methanol, for example, zirconia, alumina, silica, etc. that support or contain at least one of copper and zinc are suitable.

Further, in each of the reactors 4a and 4b, the tubular body (cylindrical molded body) 41 may be produced from the reducing agent 4R (at least one of metal and metal oxide) itself. Furthermore, a block-like or lattice-like (for example, net-like or honeycomb-like) molded body may be produced from the reducing agent 4R and arranged in the housing 42 . In these cases, the reducing agent 4R as a filler may be omitted or used together.

Among these, a configuration in which a net-like body is formed from the reducing agent 4R and arranged in the housing 42 is preferable. In the case of such a configuration, it is possible to prevent the passage resistance of the exhaust gas and the reducing gas from increasing in each of the reactors 4a and 4b, and also ensure sufficient opportunities for contact between the reducing agent 4R and the exhaust gas and the reducing gas.
The volumes of the two reactors 4a and 4b are set substantially 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). Also, the volume of at least one of the two reactors 4a and 4b may be varied according to the types of exhaust gas and reducing gas, the performance of the reducing agent 4R, and the like.

A concentration adjusting section 5, a compressing section 6, a minor component removing section 7, and an exhaust gas heating section (oxidizing gas heating section) 10 are provided in this order from the connecting section 2 side in the middle of the gas line GL1.
The concentration adjustment unit 5 adjusts so as to increase the concentration of carbon dioxide contained in the exhaust gas (in other words, concentrate the 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 adjustment unit 5, the concentration of unnecessary gas components contained in the exhaust gas can be relatively reduced. Therefore, it is possible to prevent or suppress the adverse effect of the unnecessary gas component on the conversion efficiency of carbon dioxide to carbon monoxide by the reducing agent 4R.

It is preferable that the concentration adjustment unit 5 is configured by an oxygen removal device that removes oxygen contained in the exhaust gas. As a result, the amount of oxygen brought into the gas production apparatus 1 can be reduced (that is, the concentration of oxygen contained in the exhaust gas can be adjusted to be low). For this reason, the gas composition of the exhaust gas can be deviated from the explosion range, and ignition of the exhaust gas can be prevented. Among the gas producing apparatus 1, the oxygen removal apparatus consumes a large amount of electric energy, so it is effective to use electric power as renewable energy as described later.

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 less than 0.1% by volume with respect to the entire exhaust gas. Adjusting is even more preferable. As a result, it is possible to reliably prevent the formation of detonation gas due to oxygen and reducing gas in the exhaust gas.
Oxygen removal equipment for removing oxygen contained in flue gas includes cryogenic (cryogenic) separators, pressure swing adsorption (PSA) separators, membrane separation separators, and temperature swing adsorption (TSA) separators. It can be configured using one or more of a separator of the type, a separator of the chemical absorption type, a separator of the chemisorption type, and the like.
Note that the concentration adjustment unit 5 may adjust the concentration of carbon dioxide to a high level by adding carbon dioxide to the exhaust gas.

Compressor 6 increases the pressure of the exhaust gas before it is supplied to reactors 4a and 4b. This makes it possible to increase the amount of exhaust gas that can be processed at one time in the reactors 4a and 4b. Therefore, the conversion efficiency of carbon dioxide to carbon monoxide in the reactors 4a and 4b can be further improved.
The compression unit 6 includes, for example, a centrifugal compressor, a turbo compressor such as an axial compressor, a reciprocating compressor (reciprocating compressor), a diaphragm compressor, a single screw compressor, a twin screw compressor, It can be composed of a volumetric compressor such as a scroll compressor, a rotary compressor, a rotary piston compressor, a slide vane compressor, a roots blower (two-leaf blower) capable of handling low pressure, a centrifugal blower, or the like.

Among these, the compression unit 6 is preferably configured with a centrifugal compressor from the viewpoint of easiness of increasing the scale of the gas production system 100, and from the viewpoint of reducing the production cost of the gas production system 100, A reciprocating compressor is preferred.
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 0.01 to 0.5 MPaG. More preferred. In this case, the conversion efficiency of 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.

The minor component removing unit 7 removes minor components (a small amount of unnecessary gas components, etc.) contained in the exhaust gas.
The fine component removing section 7 can be composed of, for example, at least one processor selected from a gas-liquid separator, a protector (guard reactor) and a scrubber (absorption tower).
When using a plurality of processors, their arrangement order is arbitrary, but when using a combination of a gas-liquid separator and a protector, it is preferable to arrange the gas-liquid separator upstream of the protector. . In this case, it is possible to further improve the efficiency of removing minor components from the exhaust gas, and extend the period of use (life) of the protector.

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 and removed in the condensed water.
The gas-liquid separator can be composed of, for example, a simple container, a swirling flow separator, a centrifugal separator, a surface tension separator, or the like. Among these, the gas-liquid separator is preferably configured with a simple container because of its simple configuration and low cost. In this case, a filter may be arranged at the gas-liquid interface in the container to allow passage of gas but block passage of liquid.

Also, in this case, a liquid line may be connected to the bottom of the container, and a valve may be provided in the middle of the line. According to such a 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.

The exhaust gas from which the condensed water has been removed by the gas-liquid separator can be configured to be supplied to the protector, for example.
Such a protector preferably includes a substance capable of capturing a component (inactivating component) that is a minor component contained in the exhaust gas and that reduces the activity of the reducing agent 4R upon contact with the reducing agent 4R.
According to this configuration, when the exhaust gas passes through the protector, the substance in the protector reacts (captures) with the inactivating component, thereby preventing the exhaust gas from reaching the reducing agent 4R in the reactors 4a and 4b. or can be inhibited and protected (ie, prevented from declining in activity). Therefore, it is possible to prevent or suppress an extreme decrease in the conversion efficiency of carbon dioxide to carbon monoxide by the reducing agent 4R due to the adverse effects of the inactivating component.

Such substances include substances that are contained in the reducing agent 4R and have a composition that reduces the activity of the reducing agent 4R by contact with the inactivating component, specifically, metals and metals contained in the reducing agent 4R Materials that are the same as or similar to at least one of the oxides can be used. Here, similar metal oxides refer to metal oxides that contain the same metal element but have different compositions, or metal oxides that contain different types of metal elements but belong to the same group in the periodic table. It refers to certain metal oxides.

The inactivating component is preferably at least one selected from sulfur, mercury, sulfur compounds, halogen compounds, organic silicones, organic phosphorus and organic metal compounds, and at least one selected from sulfur and sulfur compounds. Seeds are more preferred. By removing such inactivating components in advance, it is possible to effectively prevent the activity of the reducing agent 4R from abruptly decreasing.
The above substance may be any substance whose activity is lowered by the same component as the inactivating component of the reducing agent 4R. is preferred.

The protector has a structure in which a mesh material is arranged in a housing, and particles of the above substance are placed on the mesh material. A configuration in which a molded body is arranged can be employed.
In particular, when a protector is arranged between the compression unit 6 (gas-liquid separator) and the exhaust gas heating unit 10, it is necessary to improve the removal efficiency of the inactivated components while preventing the above substances from deteriorating due to heat. can be done.

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 reaction (before reduction) in the exhaust gas heating unit 10, the conversion (reduction) reaction of carbon dioxide to carbon monoxide by the reducing agent 4R is further promoted in the reactors 4a and 4b. be able to.
The exhaust gas heating section 10 can be composed of, for example, an electric heater and a heat exchanger (economizer).
The heat exchanger is configured by bending a part of the pipes forming the gas line GL4 for discharging the gas (mixed gas) after passing through the reactors 4a and 4b and bringing it closer to the pipe forming the gas line GL1. be. According to 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. can be used effectively.

Such heat exchangers include, for example, jacket heat exchangers, immersion coil heat exchangers, double tube heat exchangers, shell and tube heat exchangers, plate heat exchangers, spiral heat exchangers, and the like. Can be configured.
Further, in the exhaust gas heating section 10, either one of the electric heater and the heat exchanger may be omitted.
In the exhaust gas heating section 10, a combustion furnace or the like can be used instead of the electric heater. However, if an electric heater is used, electric power (electrical energy) as renewable energy can be used as the power source, so the load on the environment can be reduced.
As renewable energy, electric energy using at least one selected from solar power, wind power, hydraulic power, wave power, tidal power, biomass power, geothermal power, solar heat and geothermal heat is used. It is possible.

Further, on the upstream side of the exhaust gas heating unit 10 (for example, between the gas-liquid separator and the protector in the middle of the minor component removing unit 7), the exhaust gas line is branched from the gas line GL1, and the gas A vent portion provided outside the manufacturing apparatus 1 may be connected.
In this case, a valve is preferably provided in the middle of the exhaust gas line.
If the pressure in the gas production device 1 (gas line GL1) rises more than necessary, the valve is opened to discharge (release) part of the exhaust gas from the vent through the exhaust gas line. be able to. As a result, it is possible to prevent the gas production device 1 from being damaged due to an increase in pressure.

One end of the gas line GL2 is connected to the reducing gas supply section 3 . On the other hand, the gas line GL2 is connected to inlet ports of reactors 4a and 4b provided in the reaction section 4 via a gas switching section 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 of the present embodiment is composed of a hydrogen generator that generates hydrogen by electrolysis of water. 30 are connected. With this configuration, the reducing gas containing hydrogen (reducing substance) supplied from the hydrogen generator (reducing gas supply unit 3) passes through the gas line GL2 and is supplied to the reactors 4a and 4b.

According to the hydrogen generator, a large amount of hydrogen can be generated relatively cheaply and easily. Moreover, there is also an advantage that the condensed water generated in the gas production apparatus 1 can be reused. Among the gas production apparatus 1, the hydrogen generator consumes a large amount of electric energy, so it is effective to use electric power as renewable energy as described above.

A device that generates by-product hydrogen can also be used as the hydrogen generator. In this case, a reducing gas containing by-product hydrogen is supplied to each reactor 4a, 4b. As a device for generating by-product hydrogen, for example, a device for electrolyzing an aqueous solution of sodium chloride, a device for steam reforming petroleum, a device for producing ammonia, and the like can be mentioned.
Alternatively, the gas line GL2 may be connected to the coke oven outside the gas production apparatus 1 via a connecting portion, and the exhaust gas from the coke oven may be used as the reducing gas. In this case, the connecting portion constitutes the reducing gas supply portion. This is because the exhaust gas from the coke oven is mainly composed of hydrogen and methane, and contains 50 to 60% by volume of hydrogen.

A reducing gas heating unit 11 is provided in the middle of 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 pre-reaction (pre-oxidation) reducing gas 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.

The reducing gas heating section 11 can be configured in the same manner as the exhaust gas heating section 10 described above. The reducing gas heating unit 11 is preferably composed of only an electric heater, only a heat exchanger, or a combination of an electric heater and a heat exchanger, and may be composed of only a heat exchanger or a combination of an electric heater and a heat exchanger. is more preferred.
If the reducing gas heating unit 11 is equipped with a heat exchanger, the heat of the high-temperature gas (for example, mixed gas) after passing through the reactors 4a and 4b is used to heat the gas before supplying it to the reactors 4a and 4b. Since the reducing gas is heated by heat exchange, effective use of heat can be achieved.

According to the above configuration, by switching the gas line (flow path) in the gas switching unit 8, for example, the exhaust gas is supplied to the reactor 4a containing the pre-oxidized reducing agent 4R through the gas line GL3a. A reducing gas can be supplied via a gas line GL3b to the reactor 4b containing the oxidized reducing agent 4R. 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.

Note that the following formulas 1 and 2 show, as an example, the case where the reducing agent 4R contains iron oxide (FeO _x-1 ).
Equation 1: CO ₂ + FeO _x-1 → CO + FeO _x
Equation 2: H ₂ + FeO _x → H ₂ O + FeO _x−1
Thereafter, by switching the gas line in the opposite direction in the gas switching unit 8, the reaction of the above formula 2 can be allowed to proceed in the reactor 4a, and the reaction of the above formula 1 can be allowed to proceed in the reactor 4b.

That is, the reducing agent 4R produces carbon monoxide (carbon valuables) by reducing carbon dioxide. At this time, the reducing agent 4R is brought into an oxidized state by contact with carbon dioxide, but is then reduced by contact with hydrogen (reducing substance) and returns to its original state.
In this specification, the reducing agent 4R is mainly considered, the side where the reducing agent 4R is oxidized by carbon dioxide is called the "oxidation side", and the side where the oxidized reducing agent 4R is reduced by hydrogen is called the "reduction side". ” also says.

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

However, depending on the type of the 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 section for cooling the reducing agent 4R instead of the reducing agent heating section. By providing such a reducing agent cooling unit, deterioration of the reducing agent 4R during the reaction between the exhaust gas or the reducing gas and the reducing agent 4R can be suitably prevented, and the conversion efficiency of carbon dioxide to carbon monoxide can be improved. It is possible to suitably prevent or suppress the decrease and further promote the regeneration of the reducing agent 4R by the reducing gas.
In other words, it is preferable to provide the gas production device 1 with a reducing agent temperature control unit that adjusts the temperature of the reducing agent 4R depending on the type of the reducing agent 4R (exothermic reaction or endothermic reaction).

Here, the conversion rate of carbon dioxide to carbon monoxide in the reactors 4a and 4b is preferably 80% or more, 82.5% or more, 85% or more, 87.5% or more, 90% or more. It is more preferably 92.5% or more, and particularly preferably 95% or more. The upper limit of the conversion of carbon dioxide to carbon monoxide is usually about 98%.
Such a conversion rate depends on the type of reducing agent 4R used, the concentration of carbon dioxide contained in the exhaust gas, the type of reducing substance, the concentration of the reducing substance contained in the reducing gas, the temperature of the reactors 4a and 4b, the exhaust gas and the reducing gas. It can be set by adjusting the flow rate (flow velocity) of the gas to the reactors 4a and 4b, the timing of switching between the exhaust gas and the reducing gas, and the like.
The conversion rate (%) of carbon dioxide to carbon monoxide is a value calculated by the formula: CO _out /CO _2in ×100. CO _2in is the molar amount of carbon dioxide supplied to the reactors 4a and 4b, and _COout is the carbon dioxide converted to carbon monoxide by contact (reaction) with the reducing agent 4R, and from the reactors 4a and 4b It is the molar amount of carbon monoxide emitted.

On the other hand, the conversion rate of hydrogen to water in the reactors 4a and 4b is preferably 40% or higher, more preferably 45% or higher, and even more preferably 50% or higher. The upper limit of the conversion rate of hydrogen to water is usually about 85%.
Such a conversion rate depends on the type of reducing agent 4R used, the concentration of carbon dioxide contained in the exhaust gas, the type of reducing substance, the concentration of the reducing substance contained in the reducing gas, the temperature of the reactors 4a and 4b, the exhaust gas and the reducing gas. It can be set by adjusting the flow rate (flow velocity) of the gas to the reactors 4a and 4b, the timing of switching between the exhaust gas and the reducing gas, and the like.
The conversion rate (%) of hydrogen to water is a value calculated by the formula: (H _2in −H _2out )/H _2in ×100. H _2in is the molar amount of hydrogen supplied to the reactors 4a, 4b, and H _2out is the molar amount of hydrogen discharged through the reactors 4a, 4b in an unreacted state.

Gas lines GL4a and GL4b are connected to the outlet ports of the reactors 4a and 4b, respectively, and are merged at a gas junction J4 to form a gas line GL4. Further, valves (not shown) are provided in the middle of the gas lines GL4a and GL4b, respectively, as required.
For example, by adjusting the opening of the valves, the passage speed of the exhaust gas and the reducing gas passing through the reactors 4a and 4b (that is, the processing speed of the exhaust gas with the reducing agent 4R and the processing speed of the reducing agent 4R with the reducing gas) can be changed. can be set.
In this embodiment, the reaction section 4 is mainly composed of the reactors 4 a and 4 b and the gas switching section 8 .

A generated gas discharge section 40 for discharging the generated 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 and 4b.
A gas refining section 9 is provided in the middle of the gas line GL4.
The gas purification unit 9 purifies carbon monoxide from the mixed gas and recovers a generated gas containing high-concentration carbon monoxide. Incidentally, if the carbon monoxide concentration in the mixed gas is sufficiently high, the gas refining section 9 may be omitted.

The gas purifying section 9 can be composed of, for example, at least one processor selected from coolers, gas-liquid separators, gas separators, separation membranes, and scrubbers (absorption towers).
When a plurality of processors are used, their arrangement order is arbitrary, but when a cooler, a gas-liquid separator and a gas separator are used in combination, they are preferably arranged in this order. In this case, the efficiency of purifying carbon monoxide from the mixed gas can be further enhanced.

A cooler cools the mixed gas. This produces condensed water (liquid).
Such a cooler is a jacket-type cooling device in which a jacket for passing a refrigerant is arranged around the pipe, and has the same configuration as the reactors 4a and 4b (see FIG. 2), and the mixed gas is It can be configured to include a multi-pipe type cooling device, an air fin cooler, or the like, in which the refrigerant passes through the space 43 around the tubular body 41 .

The gas-liquid separator separates the condensed water generated when the mixed gas is cooled by the cooler from the mixed gas. At this time, the condensed water has the advantage of being able to dissolve and remove unnecessary gas components (particularly carbon dioxide) remaining in the mixed gas.

The gas-liquid separator can be configured in the same manner as the gas-liquid separator of the micro component removing section 7, and preferably can be configured as a simple container. In this case, a filter may be arranged at the gas-liquid interface in the container to allow passage of gas but block passage of liquid.
Also, in this case, a liquid line may be connected to the bottom of the container, and a valve may be provided in the middle of the line. According to such a configuration, the condensed water stored in the container can be discharged (released) out of the gas production apparatus 1 through the liquid line by opening the valve.

Furthermore, it is preferable to provide a drain trap downstream of the valve in the liquid line. As a result, even if the valve malfunctions and carbon monoxide or hydrogen flows out into the liquid line, it can be prevented from being stored in the drain trap and discharged outside the gas production apparatus 1 . . In place of this drain trap, or together with the drain trap, a malfunction detection function of the valve and a redundancy measure when the valve malfunctions may be provided.
Alternatively, the liquid line may be connected to the tank 30 described above to reuse the discharged condensed water.

Gas separators include, for example, cryogenic (cryogenic) separators, pressure swing adsorption (PSA) separators, membrane separation separators, temperature swing adsorption (TSA) separators, metal ion (e.g., copper ions) and organic ligands (e.g., 5-azidoisophthalic acid) are combined into a separator using a porous coordination polymer (PCP), and separation using amine absorption. It can be configured using one or more of the vessels and the like.
A valve may be provided between the gas-liquid separator and the gas separator of the gas line GL4. In this case, the mixed gas processing speed (production gas production speed) can be adjusted by adjusting the opening of the valve.

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 produced gas containing carbon monoxide at a relatively low concentration (75 to 90% by volume) can be used, carbon monoxide can be directly supplied to the next step without purifying carbon monoxide from the mixed gas. That is, the gas separator can be omitted.
Such fields include, for example, the field of synthesizing carbon valuables (e.g., ethanol, etc.) from the generated gas by fermentation with microorganisms (e.g., Clostridium, etc.), and the field of manufacturing steel using the generated gas as 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.

On the other hand, in fields where it is necessary to utilize a product gas containing relatively high concentrations (greater than 90% by volume) of carbon monoxide, the carbon monoxide is purified from the mixed gas to produce a product gas containing high concentrations of carbon monoxide. get
Such fields include, for example, the field of using generated gas as a reducing agent (blast furnace), the field of thermal power generation using generated gas as fuel, the field of manufacturing chemicals using generated gas as a raw material, and the field of manufacturing chemicals using generated gas as fuel. and the field of fuel cells used as

In this prison form, as shown in FIG. 2, return gas lines GL5a and GL5b are provided that branch from the middle of the gas lines GL4a and GL4b and are connected to the gas lines GL3a and GL3b. That is, the exhaust gas that has passed through the oxidation-side reactor 4a and is discharged from the outlet port is returned to the inlet port (upstream side) of the same oxidation-side reactor 4a, and the reduction-side reaction is performed. It is configured to return the reducing gas that has passed through the reactor 4b and is discharged from the outlet port to the inlet port (upstream side) of the same reactor 4b on the reduction side.

In addition, as described above, the exhaust gas and the reducing gas are supplied from the reactors 4a and 4b at predetermined timings. For this reason, the reactors 4a and 4b alternate between the oxidation side and the reduction side.
According to such a configuration, unreacted carbon dioxide (CO ₂ ) and unreacted hydrogen (H ₂ ) are used again to convert carbon dioxide to carbon monoxide and reduce the oxidation state with hydrogen (reducing substance). Reduction (regeneration) of agent 4R can be performed. Therefore, it is possible to further increase the production efficiency of carbon dioxide (carbon valuables).

However, it is not necessary to return both the exhaust gas and the reducing gas to the same reactors 4a and 4b, and only the gas having a lower reaction rate with the reducing agent 4R is returned to the same reactors 4a and 4b. good too. In this case, the oxidizing gas discharged from the outlet port is not returned to the inlet port (exhaust gas from the reactors 4a and 4b on the oxidation side), and the reducing gas discharged from the outlet port is returned to the inlet port (reactor on the reduction side). 4a, 4b are preferably configured to return the reducing gas).
In general, the reduction efficiency of the reducing agent 4R in the oxidized state by hydrogen (reducing substance) (in other words, the utilization efficiency of hydrogen) is lower than the conversion efficiency of carbon dioxide to carbon monoxide. Therefore, with the above configuration, the reducing agent 4R can be smoothly regenerated, which is preferable from the viewpoint of further improving the production efficiency of carbon dioxide.

Next, a usage method (action) of the gas production system 100 will be described.
[1] First, by switching the gas line (flow path) in the gas switching unit 8, the connection unit 2 and the reactor 4a are communicated, and the reducing gas supply unit 3 and the reactor 4b are communicated.
[2] Next, in this state, the supply of exhaust gas from the furnace 20 through the connecting portion 2 is started.
[3] Next, the exhaust gas passes through the oxygen removing device (concentration adjusting section 5). Oxygen is thereby removed from the exhaust gas, and the concentration of carbon dioxide contained in the exhaust gas increases.

[4] Next, the exhaust gas passes through the compression section 6 . This increases the pressure of the exhaust gas.
[5] Next, the exhaust gas passes through the minor component removing section 7 . As a result, the condensed water generated when the exhaust gas is compressed in the compression unit 6 and the inactivating components that reduce the activity of the reducing agent 4R are removed from the exhaust gas.
[6] Next, the exhaust gas passes through the exhaust gas heating section 10 . This heats the exhaust gas.
[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 brought into an oxidized state by contact with carbon dioxide.

The temperature (reaction temperature) of the reactor 4a (exhaust gas, reducing agent 4R) in the step [7] is preferably 600°C or higher, more preferably 650 to 1100°C, and more preferably 700 to 1000°C. is more preferred. If the reaction temperature is set within the above range, for example, a rapid temperature drop of the reducing agent 4R due to an endothermic reaction during conversion of carbon dioxide to carbon monoxide can be prevented or suppressed. can proceed more smoothly.

[9] Exhaust gas is discharged from the reactor 4a to the gas line GL4a.
[10] Next, the exhaust gas is returned via the return gas line GL5a, mixed with the exhaust gas supplied from the gas line GL3a, and supplied to the reactor 4a again. Similarly to the above, in the reactor 4a, the reducing agent 4R reduces carbon dioxide in the exhaust gas to carbon monoxide. At this time, the reducing agent 4R is brought into an oxidized state by contact with carbon dioxide.
The conditions of the reactor 42a can be the same as those of the reactor 41a.
It should be noted that only part of the exhaust gas discharged from the reactor 4a to the gas line GL4a may be returned via the return gas line GL5a. In this case, the remaining exhaust gas is discharged to the gas line GL4.

[11] In parallel with the above steps [2] to [10], water (reducing gas raw material) is supplied from the tank 30 to the hydrogen generator (reducing gas supply unit 3) to generate hydrogen from water.
[12] Next, the reducing gas containing hydrogen passes through the reducing gas heating section 11 . This heats the reducing gas.
[13] Next, the reducing gas is supplied to the reactor 4b. In the reactor 4b, the oxidized reducing agent 4R is reduced (regenerated) by contact with the reducing gas (hydrogen). At this time, water is produced.

The temperature (reaction temperature) of the reactor 4b (reducing gas, reducing agent 4R) in the above step [13] is preferably 600°C or higher, more preferably 650 to 1100°C, and more preferably 700 to 1000°C. It is even more preferable to have If the reaction temperature is set within the above range, for example, a rapid temperature drop of the reducing agent 4R due to an endothermic reaction during reduction (regeneration) of the reducing agent 4R in an oxidized state can be prevented or suppressed. The reduction reaction of the reducing agent 4R in can proceed more smoothly.

[14] The reducing gas is discharged from the reactor 4b to the gas line GL4b.
[15] Next, the reducing gas is returned through the return gas line GL5b, mixed with the reducing gas supplied from the gas line GL3b, and supplied to the reactor 4b. In the same manner as described above, in the reactor 4b, the reducing agent 4R in an oxidized state is reduced (regenerated) by contact with a reducing gas (hydrogen). At this time, water is produced.
The conditions of reactor 4b can be similar to reactor 4b.

[16] Next, the gases that have passed through the reactors 4a and 4b join together to produce a mixed gas. At this point, the temperature of the mixed gas is typically 600-650°C. If the temperature of the mixed gas at this time is within the above range, it means that the temperature in the reactors 4a and 4b is maintained at a sufficiently high temperature, and the conversion of carbon dioxide to carbon monoxide by the reducing agent 4R Also, it can be determined that the reduction of the reducing agent 4R by the reducing gas is progressing efficiently.
[17] Next, the mixed gas is cooled to 100 to 300° C. before reaching the gas refining section 9 .

[18] Next, the mixed gas passes through the gas refining section 9 . As a result, for example, the generated condensed water and carbon dioxide dissolved in the condensed water are removed. As a result, carbon monoxide is purified from the mixed gas to obtain a product gas containing a high concentration of carbon monoxide.
The temperature of the produced gas obtained is 20 to 50°C.
[19] Next, the generated gas is discharged from the generated gas discharge unit 40 to the outside of the gas production apparatus 1 and supplied to the next step.
Note that the gas lines GL4a and GL4b do not have to join at the gas junction J4. In this case, the exhaust gas and the reducing gas that have passed through the reactors 4a and 4b may be independently supplied to the next step via the gas lines GL4a and GL4b.

<Second embodiment>
The reaction section 4 can also be configured as follows.
FIG. 3 is a schematic diagram showing the configuration of the reaction section of the second embodiment.
Hereinafter, the reaction section 4 of the second embodiment will be described, but the description will focus on the differences from the reaction section 4 of the first embodiment, and the description of the same items will be omitted.

In the reaction section 4 of the second embodiment, a separation section 19 is provided at a branch section (communication section) between the gas lines GL4a and GL4b and the return gas lines GL5a and GL5b. This separation unit 19 is connected to the outlet port of each of the reactors 4a and 4b so as to separate the product from the reaction with the reducing agent 4R contained in the gas (exhaust gas or reducing gas) that has passed through the reactors 4a and 4b. configured to
In the present embodiment, for example, the separation unit 19 on the reduction side is configured to separate water (a product of the reaction with the reducing agent 4R) contained in the reducing gas that has passed through the reactor 4b. Note that the separation unit 19 on the oxidation side may also be configured to separate carbon monoxide (a product of the reaction with the reducing agent 4R) contained in the exhaust gas that has passed through the reactor 4a.

In this embodiment, for example, the water contained in the reducing gas that has passed through the reactor 4b on the reducing side (the product of the reaction with the reducing agent 4R) is separated. In this case, since the amount of water contained in the returned reducing gas (separated gas) is reduced, it is possible to prevent the reduction efficiency of the reducing agent 4R from decreasing even when the reducing gas is returned. Also, the amount of water contained in the mixed gas can be reduced.
The water separated by the separation unit 19 is discharged from the gas line GL19b. The gas discharged from the gas line GL19b may contain gas components other than water.

On the other hand, in the present embodiment, the exhaust gas that has passed through the oxidation-side reactor 4a is discharged to the gas line GL4 via the gas line GL4a.
The separation unit 19 connected to the oxidation-side reactor 4a may also be configured to separate carbon monoxide (a product of the reaction with the reducing agent 4R) contained in the exhaust gas.

The separation unit 19 may be composed of a condenser that condenses water (product) by cooling, and is composed of a separation membrane that allows passage of water (product) molecules and blocks passage of other molecules. It may be composed of a capture material that physically or chemically captures water (product), or it may be composed of a combination of any two or more of a cooler, a separation membrane, and a capture material. good.
The condenser can be composed of, for example, a cryogenic separation type (cryogenic type) condenser, a temperature swing adsorption (TSA) type condenser, or the like.
In addition, the separator may be composed of metal, inorganic oxide, or metal organic frameworks (MOF).

Examples of metals include titanium, aluminum, copper, nickel, chromium, cobalt, and alloys containing these. When using a metal, the separation membrane is preferably a porous body with a porosity of 80% or more.
Examples of inorganic oxides include silica and zeolite.
Examples of the metal organic structure include a structure of zinc nitrate hydrate and terephthalate dianion, a structure of copper nitrate hydrate and trimesate trianion, and the like.

The separation membrane is preferably composed of a porous material having continuous pores (pores penetrating through the cylinder wall) in which adjacent pores communicate with each other. With a separation membrane having such a configuration, the permeability of water or carbon monoxide can be increased, and the separation of water and hydrogen and/or the separation of carbon monoxide and carbon dioxide can be performed more smoothly and reliably.
Although the porosity of the separation membrane is not particularly limited, it is preferably 10 to 90%, more preferably 20 to 60%. As a result, it is possible to maintain a sufficiently high water or carbon monoxide permeability while preventing the mechanical strength of the separation membrane from significantly deteriorating.
The shape of the separation membrane is not particularly limited, and examples thereof include a cylindrical shape, a rectangular shape, and a rectangular tube shape such as a hexagonal shape.

From the viewpoint of further increasing the conversion efficiency of carbon dioxide to carbon monoxide, it is effective to increase the reduction (regeneration) efficiency of the reducing agent 4R in an oxidized state.
In this case, the average pore size of the separation membrane is preferably 600 pm or less, more preferably 400 to 500 pm. Thereby, the separation efficiency between water and hydrogen can be further improved.
Incidentally, the separation membrane is usually used in a state of being housed in a housing. In this case, the space outside the separation membrane in the housing may be depressurized, or may be allowed to pass through the carrier gas (sweep gas). Carrier gases include, for example, inert gases such as helium and argon.

Also, the separation membrane preferably has hydrophilicity. If the separation membrane has hydrophilicity, the affinity of water for the separation membrane increases, and water easily permeates the separation membrane more smoothly.
Methods of imparting hydrophilicity to the separation membrane include a method of changing the ratio of metal elements in the inorganic oxide (for example, increasing the Al/Si ratio) to improve the polarity of the separation membrane, and a method of improving the polarity of the separation membrane. Examples include a method of coating with a polymer, a method of treating the separation membrane with a coupling agent having a hydrophilic group (polar group), and a method of subjecting the separation membrane to plasma treatment, corona discharge treatment, or the like.
Furthermore, the affinity for water may be controlled by adjusting the surface potential of the separation membrane.

On the other hand, when the separation membrane preferentially separates carbon monoxide and carbon dioxide from the exhaust gas that has passed through the reactor 4a on the oxidation side, the exhaust gas and the reducing gas that have passed through both the reactors 4a and 4b On the other hand, when the separation of water and hydrogen and the separation of carbon monoxide and carbon dioxide are performed simultaneously in the separation membrane, the constituent materials of the separation membrane, the porosity, the average pore size, the hydrophilicity or hydrophobicity , the surface potential, etc. may be appropriately combined.
Although it is conceivable to configure the tubular bodies 41 of the reactors 4a and 4b with such separation membranes, in this case, the separation membranes are degraded by heat, so the temperature (reaction temperature) of the reactors 4a and 4b is set to a high temperature. I can't.
On the other hand, by arranging the separation membranes outside the reactors 4a and 4b, the temperatures of the reactors 4a and 4b can be set to relatively high temperatures, thereby improving the conversion efficiency of carbon dioxide to carbon monoxide. and the efficiency of regeneration (reduction) of the reducing agent 4R by the reducing gas can be further enhanced.

Furthermore, examples of scavengers that physically or chemically capture water include zeolite, silica gel, deciclay (clay-based desiccant), calcium chloride, calcium oxide, and the like.
On the other hand, scavengers that physically or chemically scavenge carbon monoxide include, for example, complexes of copper ions and 5-azidoisophthalic acid, copper ammine complexes, copper aluminum chloride complexes, and the like.

<Third embodiment>
The reaction section 4 can also be configured as follows.
FIG. 4 is a schematic diagram showing the configuration of the reaction section of the third embodiment.
Hereinafter, the reaction section 4 of the third embodiment will be described, but the description will focus on the differences from the reaction section 4 of the first or second embodiment, and the description of the same items will be omitted.

In the reaction section 4 of the third embodiment, the return gas lines GL5a and GL5b of the second embodiment are connected to vent lines (vent portions) VL6a and VL6b.
In the present embodiment, for example, the reduction-side vent line VL6b is configured to exhaust a part of the hydrogen (separated gas) separated by the separation unit 19 . Note that the oxidation-side vent line VL6a may also be configured to exhaust part of the carbon dioxide (separated gas) separated by the separation unit 19 .
By connecting the vent lines VL6a and VL6b and exhausting part of the separated gas on the reduction side, the amount of carbon monoxide, carbon dioxide, by-product methane, etc. in the recycling system can be reduced. . Therefore, the cost required for heating and/or cooling can be reduced, and the hydrogen conversion rate can be evaluated accurately. As a result, the operation of the gas production device 1 (gas production system 100) is facilitated.

<Fourth embodiment>
The reaction section 4 can also be configured as follows.
FIG. 5 is a schematic diagram showing the configuration of the reaction section of the fourth embodiment.
The reaction section 4 of the fourth embodiment will be described below, but the description will focus on the differences from the reaction section 4 of the first to third embodiments, and the description of the same items will be omitted.

The reaction section 4 of the fourth embodiment further has a heat exchanger (economizer) 18 .
The heat exchanger 18 is connected between the reactors 4a, 4b and the separation section 19, and bends a part of the pipes constituting the return gas lines GL5a, GL5b to the pipes constituting the gas lines GL4a, GL4b. It is constructed in close proximity.
According to such a configuration, the separated gas separated in the separation unit 19 and returned to the inlet port and the gas discharged from the outlet port after passing through the reactors 4a and 4b are heated by heat exchange, Effective use of heat can be achieved.
The heat exchanger 18 is, for example, a jacket heat exchanger, an immersion coil heat exchanger, a double tube heat exchanger, a shell and tube heat exchanger, a plate heat exchanger, a spiral heat exchanger, or the like. can be configured as

<Fifth embodiment>
The reaction section 4 can also be configured as follows.
FIG. 6 is a schematic diagram showing the configuration of the reaction section of the fifth embodiment.
The reaction section 4 of the fifth embodiment will be described below, but the description will focus on the differences from the reaction section 4 of the first to fourth embodiments, and the description of the same items will be omitted.
It should be noted that FIG. 6 does not distinguish between the oxidation side and the reduction side.

In the reaction section 4 of the fifth embodiment, two or more (at least one) reactors 4a, 4b are provided between the most downstream reactors 4a, 4b and the most upstream location where the oxidizing gas or reducing gas is returned. 4b is provided.
Specifically, in the configuration shown in FIG. 6(a), a plurality of reactors 4a and 4b are connected in series, and the separation section 19 is connected to the outlet port of the most downstream reactors 4a and 4b. The return gas lines GL5a and GL5b are connected to the inlet ports of the most upstream reactors 4a and 4b, the intermediate reactors 4a and 4b, and the most downstream reactors 4a and 4b. Incidentally, the separated gas can be returned to any place.

On the other hand, in the configuration shown in FIG. 6(b), a plurality of reactors 4a and 4b are connected in series, and the separation section 19 is connected to the outlet port of each reactor 4a and 4b. Each of the return gas lines GL5a and GL5b joins together and is connected to the inlet ports of the most upstream reactors 4a and 4b.
Also, the optional return gas lines GL5a, GL5b can be used to return the oxidizing gas or reducing gas from the given reactors 4a, 4b.
The configuration shown in FIG. 6(a) and the configuration shown in FIG. 6(b) can also be combined.

In the configuration shown in Figures 6a and 6b, this line comprises a separation section 19 connected between adjacent reactors 4a, 4b. Then, the separation unit 19 separates carbon monoxide or water (product) generated by the reaction with the reducing agent 4R contained in the exhaust gas (oxidizing gas) or reducing gas that has passed through the reactors 4a and 4b. , a separated gas with increased purity of unreacted carbon dioxide or hydrogen (reduced substance) with the reducing agent 4R is generated and returned to the upstream side of the reactors 4a and 4b. In this case, the separated gas can be partially or wholly returned. When part of the separated gas is returned, a vent line as shown in FIG. 4 is connected in the middle of the return gas lines GL5a and GL5b, and part of the separated gas is exhausted through this vent line.
According to the gas production apparatus 1 (gas production system 100) as described above, it is possible to efficiently produce carbon valuables using an oxidizing gas containing carbon dioxide and a reducing gas containing reducing substances.

In addition, it may be provided in each of the following aspects.

(1) A gas production apparatus having a plurality of reactors, each of which contains a reducing agent and can switch between an oxidizing gas containing carbon dioxide and a reducing gas containing a reducing substance to be supplied. wherein the reducing agent includes at least one of a metal and a metal oxide that generate a carbon value by reducing the carbon dioxide, and after being brought into an oxidized state by contact with the carbon dioxide, the reducing substance A part or all of at least one of the oxidizing gas and the reducing gas that has passed through each of the reactors is returned to the upstream side of the same reactor again, Gas production equipment.

(2) The gas production apparatus according to (1) above further includes a separation unit, the separation unit is connected to each of the reactors, and the reducing agent contained in the gas that has passed through the reactors is separated from the reducing agent. gas production device configured to separate the products of the reaction of

(3) The gas production apparatus according to (2) above, wherein the separation unit includes a condenser that condenses the product by cooling.

(4) In the gas production apparatus according to (2) or (3) above, the separation unit includes a separation membrane that allows passage of molecules of the product and blocks passage of other molecules. Manufacturing equipment.

(5) The gas producing apparatus according to any one of (2) to (4) above, wherein the separation unit includes a capturing material that physically or chemically captures the product.

(6) The gas production apparatus according to any one of (2) to (5) above further includes a heat exchanger, and the heat exchanger is located between the reactor and the separation section. A gas production apparatus configured to exchange heat between a separated gas that is connected, separated in the separating section and returned to the upstream side of the reactor, and a gas that has passed through the reactor.

(7) The gas production apparatus according to any one of (2) to (6) above, further comprising a vent section, the vent section is separated by the separation section, and is located upstream of the reactor. A gas production unit configured to exhaust a portion of the separated gas that is returned to the gas generator.

(8) In the gas production apparatus according to any one of (1) to (7) above, at least one A gas production apparatus comprising two reactors.

(9) The gas production apparatus according to (8) above, further comprising a separation unit connected between the adjacent reactors, wherein the separation unit includes the oxidizing gas that has passed through each of the reactors. Alternatively, by separating the product of the reaction with the reducing agent contained in the reducing gas, part or all of the separated gas in which the purity of the carbon dioxide or the reducing substance that has not reacted with the reducing agent is increased A gas production apparatus configured for return upstream of said reactor.

(10) In the gas production apparatus according to any one of (1) to (9) above, the reducing gas that has passed through the reactor is returned without returning the oxidizing gas that has passed through the reactor. A gas production device, configured to:
Of course, this is not the only case.

As described above, various embodiments of the present invention have been described, but these are presented as examples and do not limit the scope of the invention in any way. The novel embodiment can be embodied in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. The embodiment and its modifications are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

For example, the gas production apparatus of the present invention may have any other additional configuration with respect to the above embodiments, and may be replaced with any configuration that exhibits similar functions. may be omitted.
Also, any configuration of the first to fifth embodiments may be combined.
In the above embodiment, the reactor is described as a multi-tubular reactor, but the tubular body 41 may be omitted and the housing 42 may be filled directly with the reducing agent 4R.
In the above embodiments, a gas containing hydrogen was described as a representative example of the reducing gas, but the reducing gas includes hydrocarbons (eg, methane, ethane, acetylene, etc.) and ammonia as reducing substances instead of or in addition to hydrogen. A gas containing at least one selected from can also be used.

Reference Signs List 1: Gas production device 2: Connection part 3: Reducing gas supply part 4: Reaction part 41: Tubular body 42: Housing 43: Space 4R: Reducing agent 4a: Reactor 4b: Reactor 5: Concentration adjustment part 6: Compression part 7: Minor component removing unit 8: Gas switching unit 8a: First gas switching unit 8b: Second gas switching unit 9: Gas refining unit 10: Exhaust gas heating unit 11: Reducing gas heating unit 18: Heat exchanger 19: Separating unit 20: Furnace 30: Tank 40: Generated gas discharge unit 100: Gas production system GL1: Gas line GL2: Gas line GL3a: Gas line GL3b: Gas line GL3c: Gas line GL3d: Gas line GL4: Gas line GL4a: Gas line GL4b : Gas line GL4c : Gas line GL4d : Gas line GL5a : Return gas line GL5b : Return gas line GL19a : Gas line GL19b : Gas line VL6a : Vent line VL6b : Vent line J4 : Gas junction

Claims (10)

1. A gas production device,
   having multiple reactors,
   Each of the reactors accommodates a reducing agent and is configured to be capable of switching between an oxidizing gas containing carbon dioxide and a reducing gas containing a reducing substance, and
   The reducing agent contains at least one of a metal and a metal oxide that generate a carbon value by reducing the carbon dioxide, and is brought into an oxidized state by contact with the carbon dioxide, and then contacted with the reducing substance. is reduced by
   A gas production apparatus configured to return part or all of at least one of the oxidizing gas and the reducing gas that have passed through each of the reactors to the upstream side of the same reactor.
2. In the gas production apparatus according to claim 1,
   Furthermore, it has a separation part,
   The gas production apparatus, wherein the separation unit is connected to each of the reactors and is configured to separate a product from the reaction with the reducing agent contained in the gas that has passed through the reactors.
3. In the gas production apparatus according to claim 2,
   The gas production apparatus, wherein the separation unit includes a condenser that condenses the product by cooling.
4. In the gas production apparatus according to claim 2 or 3,
   The gas production apparatus, wherein the separation unit includes a separation membrane that allows passage of molecules of the product and blocks passage of other molecules.
5. In the gas production apparatus according to any one of claims 2 to 4,
   The gas production apparatus, wherein the separation unit includes a capture material that physically or chemically captures the product.
6. In the gas production apparatus according to any one of claims 2 to 5,
   Furthermore, having a heat exchanger,
   The heat exchanger is connected between the reactor and the separation section, separates the separated gas in the separation section and returns to the upstream side of the reactor, and the gas that has passed through the reactor. A gas-producing device configured to exchange heat therebetween.
7. In the gas production apparatus according to any one of claims 2 to 6,
   Furthermore, it has a vent part,
   The gas production apparatus, wherein the vent section is configured to exhaust part of the separated gas that is separated in the separation section and returned to the upstream side of the reactor.
8. In the gas production apparatus according to any one of claims 1 to 7,
   A gas production apparatus, wherein at least one reactor is provided between the reactor and an upstream location where the oxidizing gas or the reducing gas is returned.
9. In the gas production apparatus according to claim 8,
   Furthermore, having a separation unit connected between the adjacent reactors,
   The separation unit separates a product of the reaction with the reducing agent contained in the oxidizing gas or the reducing gas that has passed through each of the reactors, so that the carbon dioxide that has not reacted with the reducing agent or the A gas production apparatus configured to return part or all of the separated gas with increased purity of reducing substances to the upstream side of the reactor.
10. In the gas production apparatus according to any one of claims 1 to 9,
    A gas production apparatus configured to return the reducing gas that has passed through the reactor without returning the oxidizing gas that has passed through the reactor.

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