Reaction system

Abstract

To provide a reaction system capable of suppressing delay of reaction start of a raw material gas and enhancing concentration of a formed hydrocarbon.SOLUTION: A reaction system 1 is equipped with a reaction unit 40 that houses reaction tubes 41 and has a shell 42 containing a space 46 through which a liquid heat medium 49 passes. The liquid heat medium 49 passes through the space 46 and exchanges heat with the reaction tubes 41 and thus a part of the liquid heat medium 49 evaporates in the space 46. The reaction unit 40 is fabricated so that a gas heat medium 50 formed from a part of the liquid heat medium 49 contacts with the upstream part of the reaction tubes 41 closer to an inlet port 44 than to an outlet port 45, whereas the liquid heat medium 49 contacts with the downstream part of the reaction tubes 41 closer to the outlet port 45 than to the inlet port 44.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a reaction system.

Background Art

[0002] Carbon dioxide is regarded as a problem as a cause of global warming, and globally, movements to suppress carbon dioxide emissions are becoming active. As a method of reducing the amount of carbon dioxide discharged into the atmosphere and effectively using carbon dioxide, a methanation technology for producing methane from carbon dioxide in exhaust gas is known. Methanation is an exothermic reaction, and if the reaction temperature becomes too high, the methane concentration generated becomes low. Therefore, a mechanism for cooling the reaction tube is provided in the methanation reaction device.

[0003] Patent Document 1 discloses a reaction device including one or a plurality of reaction tubes in which a raw material gas is subjected to a methanation reaction in the presence of a catalyst. The reaction tube has an inlet for the raw material gas not only at one end but also at an intermediate portion. Thereby, the reaction efficiency of the methanation reaction is increased more than before by making the reaction temperature in the reaction tube uniform. The reaction tube is cooled by exchanging heat with a heat medium so that the reaction tube maintains the target temperature.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As mentioned above, methanation is an exothermic reaction, so if the temperature of the heat transfer medium is lowered, the reaction will proceed in a way that increases the methane concentration from the standpoint of chemical equilibrium. However, if the temperature of the heat transfer medium is lowered, the reaction will start later, and there is a risk that the raw material gas will be discharged from the reaction tube before the reaction is complete. On the other hand, if the temperature of the heat transfer medium is higher, the reaction will start earlier, but because methanation is an exothermic reaction, the reaction may stop once it reaches a certain point, and there is a risk that the methane concentration discharged from the reaction tube will be low.

[0006] Therefore, the present disclosure aims to provide a reaction system that can suppress the delay in the start of the reaction of the raw material gas and increase the concentration of hydrocarbons produced. [Means for solving the problem]

[0007] The reaction system according to this disclosure includes a heating section for heating a raw material gas containing at least one of carbon monoxide and carbon dioxide, as well as hydrogen. The reaction system includes a reaction tube containing a catalyst that generates hydrocarbons upon contact with the raw material gas, an inlet into which the raw material gas heated in the heating section is introduced, and an outlet from which the hydrocarbons generated by contact with the catalyst are discharged, and a shell containing the reaction tube and having a space through which a liquid heat transfer medium passes. The reaction section is configured such that the liquid heat transfer medium exchanges heat with the reaction tube as it passes through the space, causing a portion of the liquid heat transfer medium to vaporize in the space, and a gaseous heat transfer medium generated from the portion of the liquid heat transfer medium comes into contact with the upstream part of the reaction tube, which is closer to the inlet than the outlet, and the liquid heat transfer medium comes into contact with the downstream part of the reaction tube, which is closer to the outlet than the inlet.

[0008] The liquid heat transfer medium may have a boiling point of 200°C or higher and 250°C or lower under pressures above standard atmospheric pressure.

[0009] The shell may have a liquid supply port for supplying a liquid heat transfer medium and a liquid outlet for discharging the liquid heat transfer medium. The liquid supply port and liquid outlet may be located closer to the bottom of the space holding the liquid heat transfer medium than the gas-liquid interface between the liquid heat transfer medium and the gaseous heat transfer medium.

[0010] The reaction system may further include a pressure control unit for controlling the gas pressure in the space.

[0011] The pressure control unit is in communication with space and may include a buffer tank that absorbs pressure fluctuations when a portion of the liquid heat transfer medium vaporizes.

[0012] The reaction system may further include a liquid level control unit that controls the liquid level of the liquid heat transfer medium within the shell.

[0013] A gaseous heat transfer medium may be used as the heat source for the heating section. [Effects of the Invention]

[0014] According to this disclosure, it is possible to provide a reaction system that can suppress the delay in the start of the reaction of the raw material gas and increase the concentration of hydrocarbons produced. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic diagram showing a reaction system according to one embodiment. [Figure 2] This is a schematic diagram showing the structure of the reaction section and its surrounding area according to one embodiment. [Figure 3] This is a schematic graph showing an example of the change in reaction temperature according to one embodiment. [Modes for carrying out the invention]

[0016] Several exemplary embodiments will be described below with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for illustrative purposes and may differ from the actual ratios.

[0017] As shown in Figure 1, the reaction system 1 according to this embodiment includes a carbon dioxide supply unit 10, a hydrogen supply unit 20, a heating unit 30, a reaction unit 40, a liquid level control unit 60, a pressure control unit 70, and an accumulator 80.

[0018] The carbon dioxide supply unit 10 supplies the carbon dioxide contained in the raw material to the heating unit 30. The carbon dioxide supply unit 10 may be a tank storing carbon dioxide, or may include a carbon dioxide recovery unit that recovers the carbon dioxide discharged from a carbon dioxide generation source such as a power plant and a factory. By using the carbon dioxide recovered from the carbon dioxide generation source as a raw material for hydrocarbons, the amount of carbon dioxide released into the atmosphere can be reduced, and useful hydrocarbons can be produced. Also, if hydrocarbons can be produced using carbon dioxide as a raw material, the use of petroleum, which is a finite resource, can also be reduced. The carbon dioxide recovery unit can recover carbon dioxide by, for example, a chemical absorption method, a pressure swing adsorption method, a temperature swing adsorption method, a membrane separation and concentration method, or a combination thereof.

[0019] The hydrogen supply unit 20 supplies the hydrogen contained in the raw material to the heating unit 30. The hydrogen supply unit 20 is not particularly limited as long as it can supply hydrogen to the reaction unit 40, but hydrogen obtained by electrolyzing water using renewable energy such as sunlight, wind power, and hydraulic power may be used. By using such hydrogen, the carbon dioxide emission amount of the entire reaction system 1 can be reduced.

[0020] The heating unit 30 heats the raw material gas. The heating unit 30 may heat the raw material gas to, for example, 300°C to 350°C. In this embodiment, a mixed gas containing hydrogen and carbon dioxide is heated by the heating unit 30, and the heated mixed gas is supplied to the reaction unit 40. However, the heating unit 30 may include a hydrogen heating unit that heats hydrogen and a carbon dioxide heating unit that heats carbon dioxide. And a raw material gas containing the hydrogen gas heated by the hydrogen heating unit and the carbon dioxide gas heated by the carbon dioxide heating unit may be supplied to the reaction unit 40.

[0021] In the raw material gas supplied to the reaction unit 40, the ratio of hydrogen to carbon dioxide can be set as appropriate, for example, it may be 1 or more in molar ratio, 2 or more, 3 or more, 3.5 or more, or 4 or more. Also, in the raw material gas supplied to the reaction unit 40, the ratio of hydrogen to carbon dioxide may be less than 8 in molar ratio, less than 6, less than 5, or less than 4.5. In the case of a methanation reaction, the ratio of hydrogen to carbon dioxide in the raw material gas supplied to the reaction unit 40 may be the stoichiometric ratio of 4.

[0022] As shown in Figure 2, the reaction section 40 includes a reaction tube 41 and a shell 42 that houses the reaction tube 41. The reaction tube 41 contains a catalyst 43 that promotes the generation of hydrocarbons by contact with the raw material gas. The reaction tube 41 also has an inlet 44 into which the raw material gas heated in the heating section 30 is introduced, and an outlet 45 out which the hydrocarbons generated by contact with the catalyst 43 are discharged. When the raw material gas is introduced from the inlet 44 and comes into contact with the catalyst 43, the reaction is promoted and heat is generated. The reaction tube 41 in this embodiment may be a straight tube, a spiral tube, a corrugated tube, an S-shaped tube, or a curved tube. Among these, the reaction tube 41 is preferably a straight tube because it is easy to clean and fill with the catalyst 43. The reaction tube 41 may also have an enlarged diameter section or a reduced diameter section, or it may not have an enlarged diameter section or a reduced diameter section. The reaction section 40 may have a single reaction tube 41 or a plurality of reaction tubes 41.

[0023] The reaction product contains hydrocarbons. By producing hydrocarbons in the reaction section 40, not only can the emission of carbon dioxide be suppressed, but carbon dioxide can also be effectively utilized as a raw material for fuels and chemical products. The hydrocarbons produced in the reaction section 40 may contain at least one of alkanes and alkenes. These hydrocarbons can be produced by a methanation reaction or a Fischer-Tropsch reaction. At least one of alkanes and alkenes may contain hydrocarbons having 1 to 4 carbon atoms. Examples of alkanes having 1 to 4 carbon atoms include methane, ethane, propane, and butane. Examples of alkenes having 1 to 4 carbon atoms include ethylene, propylene, 1-butene, 2-butene, isobutene, and 1,3-butadiene. Among these, methane, ethane, and propane can be used as fuels for city gas. In addition, alkenes having 2 to 4 carbon atoms are useful because they can also be used as raw materials for plastics. Note that the reaction product may contain compounds other than those described above.

[0024] The catalyst 43 is selected from the viewpoint of the type of hydrocarbons to be produced, and a known catalyst such as an iron catalyst or a cobalt catalyst can be used. In the case of an iron catalyst, light hydrocarbons can be mainly produced, and in the case of a cobalt catalyst, heavy hydrocarbons containing wax can be mainly produced. Also, in the case of an iron catalyst, alkenes and alkanes can be mainly produced, and in the case of a cobalt catalyst, alkanes can be mainly produced. Note that an iron catalyst is a catalyst containing iron as an active component, and a cobalt catalyst is a catalyst containing cobalt as an active component.

[0025] The shell 42 has a space 46 between it and the reaction tube 41. The shell 42 has a liquid supply port 47 and a liquid outlet 48. The liquid supply port 47 is a supply port for supplying liquid heat transfer medium 49. A liquid supply channel 51 is connected to the liquid supply port 47 for guiding the liquid heat transfer medium 49 into the liquid supply port 47. The liquid outlet 48 is an outlet for discharging the liquid heat transfer medium 49. A liquid outlet channel 52 is connected to the liquid outlet 48 for guiding out the liquid heat transfer medium 49 discharged from the liquid outlet 48. The liquid heat transfer medium 49 passes through the space 46 as it is supplied to the space 46 in the shell 42 via the liquid supply port 47 and discharged from the space 46 via the liquid outlet 48.

[0026] The liquid heat transfer medium 49 passes through the space 46 and exchanges heat with the reaction tube 41. Specifically, the liquid heat transfer medium 49 supplied to the space 46 in the shell 42 comes into contact with the reaction tube 41, and heat is exchanged between the heat of the reaction tube 41 and the heat of the liquid heat transfer medium 49. As heat is exchanged between the liquid heat transfer medium 49 and the reaction tube 41, heat is exchanged between the reaction tube 41 and the gas inside the reaction tube 41. Specifically, the reaction tube 41 is cooled by the liquid heat transfer medium 49, and this cools the gas inside the reaction tube 41. In addition, as the liquid heat transfer medium 49 exchanges heat with the reaction tube 41, a portion of the liquid heat transfer medium 49 vaporizes in the space 46, and gaseous heat transfer medium 50 is generated from a portion of the liquid heat transfer medium 49.

[0027] The shell 42 has a gas outlet 53. The gas outlet 53 is an outlet for discharging the gaseous heat medium 50 which is formed when the liquid heat medium 49 is vaporized. A gas discharge channel 54 is connected to the gas outlet 53 to guide out the gaseous heat medium 50 discharged from the gas outlet 53. The gaseous heat medium 50 discharged from the space 46 inside the shell 42 is supplied to the accumulator 80 via the gas discharge channel 54.

[0028] The reaction section 40 is configured such that the gaseous heat transfer medium 50 is in contact with the upstream part of the reaction tube 41, which is closer to the inlet 44 than the outlet 45, and the liquid heat transfer medium 49 is in contact with the downstream part of the reaction tube 41, which is closer to the outlet 45 than the inlet 44. The gaseous heat transfer medium 50 has a lower heat transfer coefficient with the reaction tube 41 and lower heat exchange efficiency compared to the liquid heat transfer medium 49. Therefore, in the upstream part of the reaction tube 41, the gas inside the reaction tube 41 is cooled slowly, and a rapid temperature drop is unlikely to occur. This allows the exothermic reaction to continue while suppressing a decrease in the reaction rate. Thus, the delay in the start of the reaction of the raw material gas can be suppressed. On the other hand, in the downstream part of the reaction tube 41, the heat transfer coefficient between the reaction tube 41 and the liquid heat transfer medium 49 is high, resulting in high heat exchange efficiency. Also, the temperature of the liquid heat transfer medium 49 is lower than the temperature of the gaseous heat transfer medium 50. As a result, in the downstream part of the reaction tube 41, the heat associated with the exothermic reaction is efficiently removed, thus promoting the hydrocarbon production reaction. Therefore, the concentration of hydrocarbons produced can be increased.

[0029] In this embodiment, the gas outlet 53 is located closer to the inlet 44 than the liquid supply port 47 and the liquid outlet 48 in the direction of extension of the line segment connecting the inlet 44 and the outlet 45 of the reaction tube 41. This allows the reaction section 40 to be configured such that the gaseous heat transfer medium 50 is in contact with the upstream part of the reaction tube 41 and the liquid heat transfer medium 49 is in contact with the downstream part of the reaction tube 41. However, the positions of the liquid supply port 47, the liquid outlet 48 and the gas outlet 53 are not particularly limited. For example, the liquid supply port 47 may be located closer to the inlet 44 than the gas outlet 53, and the liquid heat transfer medium 49 may be allowed to flow down from the area in the space 46 that is filled with the gaseous heat transfer medium 50. Even in such a case, the reaction section 40 can be configured such that the gaseous heat transfer medium 50 is in contact with the upstream part of the reaction tube 41 and the liquid heat transfer medium 49 is in contact with the downstream part of the reaction tube 41.

[0030] In this embodiment, the liquid supply port 47 and the liquid outlet port 48 are located closer to the bottom 56 of the space 46 that holds the liquid heat transfer medium 49 than to the gas-liquid interface 55 between the liquid heat transfer medium 49 and the gaseous heat transfer medium 50. With this arrangement, the liquid heat transfer medium 49 flows closer to the bottom 56. The liquid heat transfer medium 49, heated by the reaction tube 41, moves towards the inlet 44 of the reaction tube 41. Also, since the temperature of the gas flowing inside the reaction tube 41 is higher on the inlet 44 side than on the outlet 45 side, the temperature of the liquid heat transfer medium 49 in the space 46 also tends to be higher on the inlet 44 side than on the outlet 45 side. Therefore, a temperature gradient is created in the liquid heat transfer medium 49, and the temperature of the liquid heat transfer medium 49 decreases as it moves downstream in the reaction tube 41. As a result, the gas in the reaction tube 41 is cooled slowly as it moves from the inlet 44 to the outlet 45. This allows the reaction to proceed rapidly in the upstream part of the reaction tube 41, while the exothermic reaction (hydrocarbon production reaction) proceeds in the downstream part of the reaction tube 41, thereby increasing the hydrocarbon concentration. Furthermore, by setting the temperature of the liquid heat transfer medium 49 supplied to the space 46 inside the shell 42 to a low temperature such as room temperature, it becomes unnecessary to provide a cooling device to cool the generated hydrocarbons, or the energy required for cooling can be reduced.

[0031] The liquid heat transfer medium 49 may have a boiling point of 200°C to 250°C under pressure above standard atmospheric pressure. By using such a liquid heat transfer medium 49, hydrocarbons can be effectively cooled. Furthermore, the gaseous heat transfer medium 50 generated from such a liquid heat transfer medium 49 has a large amount of energy, and can be effectively utilized by storing it in the accumulator 80, for example. The liquid heat transfer medium 49 may contain at least one of water and an organic solvent. Examples of organic solvents include alcohols such as ethanol and propanol, but are not particularly limited. Among these, it is preferable that the liquid heat transfer medium 49 contains water, as it has a large heat of vaporization, efficiently removes heat from the reaction tube 41, and is easy to obtain and manage. In addition, the water may contain a small amount of additives to impart functionality.

[0032] The liquid level control unit 60 controls the liquid level of the liquid heat transfer medium 49 inside the shell 42. By controlling the liquid level by the liquid level control unit 60, it is possible to prevent the liquid level of the liquid heat transfer medium 49 from rising too high, which would cause the reaction to stop or delay the start of the reaction. Also, by controlling the liquid level by the liquid level control unit 60, it is possible to prevent the liquid level of the liquid heat transfer medium 49 from falling too low, which would cause the temperature inside the reaction tube 41 to rise and reduce the yield of hydrocarbons. Note that if the liquid level can be controlled to a constant condition through prior trial runs, the reaction system 1 does not need to be equipped with the liquid level control unit 60. Furthermore, the liquid level control unit 60 may include a liquid level gauge 61, a first flow rate adjustment unit 62, and a second flow rate adjustment unit 63.

[0033] The liquid level gauge 61 is provided in the reaction section 40 and measures the liquid level of the liquid heat transfer medium 49 inside the shell 42. The liquid level gauge 61 may measure the liquid level continuously or measure at a predetermined liquid level position. Known liquid level gauges such as electrode type liquid level gauges, float type liquid level gauges, ultrasonic type liquid level gauges, capacitance type liquid level gauges, and differential pressure type liquid level gauges can be used for the liquid level gauge 61. Since the liquid surface may become wavy or bubbles may form due to boiling of the liquid heat transfer medium 49, it is preferable that the liquid level gauge 61 be a differential pressure type liquid level gauge.

[0034] The first flow rate adjustment unit 62 is located in the liquid supply channel 51 and adjusts the flow rate of the liquid heat transfer medium 49 supplied to the reaction section 40. The second flow rate adjustment unit 63 is located in the liquid discharge channel 52 and adjusts the flow rate of the liquid heat transfer medium 49 discharged from the reaction section 40. The liquid level gauge 61 and the first flow rate adjustment unit 62 are electrically connected. The liquid level control unit 60 can adjust the flow rate of the supplied liquid heat transfer medium 49 using the first flow rate adjustment unit 62 based on the liquid level of the liquid heat transfer medium 49 measured by the liquid level gauge 61. The liquid level gauge 61 and the second flow rate adjustment unit 63 are also electrically connected. The liquid level control unit 60 can adjust the flow rate of the discharged liquid heat transfer medium 49 using the second flow rate adjustment unit 63 based on the liquid level of the liquid heat transfer medium 49 measured by the liquid level gauge 61.

[0035] The pressure control unit 70 controls the gas pressure in the space 46 within the shell 42. By controlling the pressure in the space 46 within the shell 42 by the pressure control unit 70, the boiling point of the liquid heat transfer medium 49 can be controlled. Therefore, the temperature near the liquid surface of the liquid heat transfer medium 49 can be maintained at a temperature suitable for the reaction. For example, when water is used as the liquid heat transfer medium 49, the boiling point of water at atmospheric pressure is 100°C, but by controlling the pressure in the space 46 within the shell 42 to 1.5 MPaG to 4 MPaG, the boiling point can be set to 200°C to 250°C. Note that, for example, if a liquid heat transfer medium 49 whose boiling point at standard atmospheric pressure is within a predetermined range is used, the reaction system 1 does not need to be equipped with the pressure control unit 70.

[0036] The pressure control unit 70 may include a pressure gauge 71 and a pressure adjustment unit 72. The pressure gauge 71 is provided in the reaction unit 40 and measures the gas pressure in the space 46 inside the shell 42. The pressure adjustment unit 72 is provided in the gas discharge passage 54 and adjusts the pressure in the space 46 inside the shell 42. The pressure adjustment unit 72 may be a pressure adjustment valve. The pressure gauge 71 and the pressure adjustment unit 72 are electrically connected. The pressure adjustment unit 72 may adjust the gas pressure in the space 46 inside the shell based on the gas pressure in the space 46 inside the shell measured by the pressure gauge 71.

[0037] The pressure control unit 70 is in communication with the space 46 and may include a buffer tank 73 that absorbs pressure fluctuations when a portion of the liquid heat transfer medium 49 vaporizes. By including the buffer tank 73 in the pressure control unit 70, pressure fluctuations in the space 46 due to the boiling of the liquid heat transfer medium 49 can be absorbed in the space within the buffer tank 73. As a result, the gas pressure in the space 46 becomes uniform, allowing for more accurate control of the pressure in the space 46. Furthermore, if a differential pressure type liquid level gauge 61 is used, the liquid level can be controlled more easily and accurately.

[0038] The accumulator 80 stores the gaseous heat transfer medium 50 discharged from the reaction section 40 as a liquid heat transfer medium 49. The accumulator 80 may also be a steam accumulator. The liquid heat transfer medium 49 stored in the accumulator 80 may be supplied to a boiler and / or factory as needed. This allows for the effective utilization of the heat generated by the exothermic reaction in the reaction section 40.

[0039] The gaseous heat transfer medium 50 discharged from the gas outlet 53 may also be used as a heat source for the heating unit 30. In this embodiment, the gaseous heat transfer medium 50 discharged from the gas outlet 53 is supplied to the heating unit 30 via the accumulator 80. However, it may also be supplied directly to the heating unit 30 without going through the accumulator 80.

[0040] Next, using Figure 3, an example of the reaction temperature progression will be outlined. First, the raw material gas, a mixture of carbon dioxide supplied from the carbon dioxide supply unit 10 and hydrogen supplied from the hydrogen supply unit 20, is heated to approximately 300°C to 350°C in the heating unit 30. The heated raw material gas is introduced through the inlet 44 of the reaction tube 41. When the raw material gas comes into contact with the catalyst 43, the reaction of the raw material gas begins, and the temperature rises due to the exothermic reaction.

[0041] The upstream portion of the reaction tube 41 is in contact with the gaseous heat transfer medium 50. The heat transfer coefficient between the reaction tube 41 and the gaseous heat transfer medium 50 is low, and the heat exchange efficiency is not very high, so the rapid cooling of the raw material gas is suppressed. Therefore, the stopping of the reaction or the delay in the start of the reaction is suppressed. In this embodiment, the temperature rise inside the reaction tube 41 due to the exothermic reaction exceeds the cooling rate by the gaseous heat transfer medium 50, so the temperature of the gas inside the reaction tube 41 rises. This promotes the hydrocarbon production reaction.

[0042] At the gas-liquid interface 55 between the liquid heat transfer medium 49 and the gaseous heat transfer medium 50, heat can be efficiently removed from the reaction tube 41 by the heat of vaporization when the liquid heat transfer medium 49 gasifies. Therefore, the cooling rate of the gas in the reaction tube 41 increases near the gas-liquid interface 55. Furthermore, the downstream part of the reaction tube 41 is in contact with the liquid heat transfer medium 49. The reaction tube 41 and the liquid heat transfer medium 49 have a high heat transfer coefficient and high heat exchange efficiency. Also, the temperature of the liquid heat transfer medium 49 is lower than the temperature of the gaseous heat transfer medium 50. Therefore, the gas in the reaction tube 41 cools even faster and moves towards the outlet 45 of the reaction tube 41. In the downstream part of the reaction tube 41, the heat associated with the exothermic reaction is efficiently removed, so from the perspective of chemical equilibrium, the hydrocarbon production reaction is promoted and the hydrocarbon concentration increases. For example, in the case of methanation, the methane production reaction begins to stop at around 300°C to 350°C. Furthermore, if water at 20°C to 30°C is supplied as the heat transfer medium, the temperature of the hydrocarbon discharged from outlet 45 can be reduced to around 50°C to 70°C.

[0043] In this embodiment, the reaction system 1 produced hydrocarbons using a raw material gas containing carbon dioxide and hydrogen. However, the raw material gas may also contain carbon monoxide and hydrogen, or carbon monoxide, carbon dioxide, and hydrogen. That is, the raw material gas may contain at least one of carbon monoxide and carbon dioxide. Even when hydrocarbons are produced using such raw materials, an exothermic reaction occurs. Therefore, the reaction temperature can be controlled by the reaction system 1 described above.

[0044] As described above, the reaction system 1 according to this embodiment comprises a heating unit 30 and a reaction unit 40. The heating unit 30 heats a raw material gas containing at least one of carbon monoxide and carbon dioxide, as well as hydrogen. The reaction unit 40 includes a reaction tube 41 and a shell 42. The reaction tube 41 houses a catalyst 43 that generates hydrocarbons upon contact with the raw material gas, and has an inlet 44 through which the raw material gas heated in the heating unit 30 is introduced, and an outlet 45 through which the hydrocarbons generated by contact with the catalyst 43 are discharged. The shell 42 houses the reaction tube 41 and has a space 46 through which a liquid heat transfer medium 49 passes. The reaction unit 40 is configured such that the liquid heat transfer medium 49 passes through the space 46 and exchanges heat with the reaction tube 41, causing a portion of the liquid heat transfer medium 49 to vaporize in the space 46. The reaction unit 40 is configured such that a gaseous heat transfer medium 50 generated from a portion of the liquid heat transfer medium 49 comes into contact with the upstream portion of the reaction tube 41, which is closer to the inlet 44 than to the outlet 45. Furthermore, the reaction section 40 is configured such that the liquid heat transfer medium 49 is in contact with the downstream portion of the reaction tube 41, which is closer to the outlet 45 than to the inlet 44.

[0045] The gaseous heat transfer medium 50 is in contact with the upstream part of the reaction tube 41, and the liquid heat transfer medium 49 is in contact with the downstream part of the reaction tube 41. This prevents the raw material gas heated in the heating section 30 from cooling rapidly. As a result, it prevents the reaction from stopping or the start of the reaction from being delayed. In addition, the liquid heat transfer medium 49 has a high heat exchange efficiency with the reaction tube 41 and is at a lower temperature than the gaseous heat transfer medium 50, so from the perspective of chemical equilibrium, it can promote the reaction of hydrocarbons and increase the concentration of hydrocarbons produced.

[0046] Therefore, according to the reaction system 1 of this embodiment, it is possible to suppress the delay in the start of the reaction of the raw material gas and increase the concentration of hydrocarbons produced.

[0047] Although several embodiments have been described, it is possible to modify or transform the embodiments based on the above disclosure. All components of the above embodiments, and all features described in the claims, may be taken individually and combined, provided that they do not conflict with each other.

[0048] This disclosure can contribute, for example, to United Nations Sustainable Development Goal 13, "Take urgent action to combat climate change and its impacts." [Explanation of symbols]

[0049] 1. Reaction System 30 Heating section 40 Reaction section 41 reaction tube 42 shells 43 Catalyst 44 Inlet 45 Outlet 46 Space 47 Liquid supply port 48 Liquid outlet 49 Liquid heat transfer medium 50 Gaseous heat transfer medium 55 Air-liquid interface 56 Bottom 60 Liquid level control unit 70 Pressure Control Unit 73 Buffer Tank

Claims

1. A heating section for heating a raw material gas containing at least one of carbon monoxide and carbon dioxide, and hydrogen, A reaction section comprising a reaction tube containing a catalyst that generates hydrocarbons upon contact with the raw material gas, having an inlet into which the raw material gas heated in the heating section is introduced, and an outlet from which the hydrocarbons generated upon contact with the catalyst are discharged, and a shell containing the reaction tube and having a space through which a liquid heat transfer medium passes, Equipped with, The reaction section is configured such that the liquid heat transfer medium passes through the space and exchanges heat with the reaction tube, causing a portion of the liquid heat transfer medium to vaporize in the space, and the gaseous heat transfer medium generated from the portion of the liquid heat transfer medium comes into contact with the upstream part of the reaction tube, which is closer to the inlet than the outlet, and the liquid heat transfer medium comes into contact with the downstream part of the reaction tube, which is closer to the outlet than the inlet. The shell has a liquid supply port for supplying the liquid heat transfer medium and a liquid discharge port for discharging the liquid heat transfer medium. A reaction system in which the liquid supply port and the liquid discharge port are located closer to the bottom of the space holding the liquid heat medium than the gas-liquid interface between the liquid heat medium and the gaseous heat medium.

2. The reaction system according to claim 1, wherein the liquid heat transfer medium has a boiling point of 200°C or higher and 250°C or lower under a pressure of standard atmospheric pressure or higher.

3. The reaction system according to claim 1 or 2, further comprising a pressure control unit for controlling the gas pressure in the aforementioned space.

4. The reaction system according to claim 3, wherein the pressure control unit is in communication with the space and includes a buffer tank that absorbs pressure fluctuations when a portion of the liquid heat transfer medium vaporizes.

5. The reaction system according to any one of claims 1 to 4, further comprising a liquid level control unit for controlling the liquid level of the liquid heat transfer medium in the shell.

6. The reaction system according to any one of claims 1 to 5, wherein the gaseous heat transfer medium is used as the heat source for the heating section.

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