Methane production equipment
The methane production apparatus optimizes catalyst temperatures and reduces catalyst usage through a heat transfer medium flow path and separate activation, achieving efficient and energy-saving methane production.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-06-29
- Publication Date
- 2026-03-04
AI Technical Summary
Existing methane production technologies require more expensive methanation catalysts due to unsuitable temperature ranges for the catalysts in the reactors, leading to inefficient use.
A methane production apparatus with reactors that include heating, reaction, and cooling units, utilizing a heat transfer medium flow path to maintain optimal catalyst temperatures and reduce catalyst usage, and a separate heat medium flow path for activation, allowing efficient methane production with reduced catalyst amounts.
The apparatus achieves efficient methane production by maintaining optimal catalyst temperatures, reducing catalyst usage, and optimizing energy consumption, thereby enhancing time and energy savings.
Smart Images
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Abstract
Description
[Technical Field]
[0001] The present invention relates to a methane production apparatus. [Background technology]
[0002] Patent Document 1 discloses a methane production apparatus that produces methane by passing a raw material gas composed of hydrogen and carbon dioxide through a first reactor and a second reactor connected in series. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-083799 Summary of the Invention [Problem to be solved by the invention]
[0004] In the technology disclosed in Patent Document 1, raw material gas at room temperature is introduced into the first reactor, and reaction gas cooled to room temperature to remove condensed water is introduced into the second reactor, so that the methanation catalyst with which the raw material gas comes into contact in the first and second reactors has a catalyst region in a temperature range unsuitable for reaction. The technology disclosed in Patent Document 1 has the problem of using more expensive methanation catalyst than necessary.
[0005] In view of such problems, the present disclosure aims to provide a methane production apparatus that can reduce the amount of methanation catalyst. [Means for solving the problem]
[0006] A methane production apparatus according to the present disclosure is an apparatus for producing methane by passing a raw material gas containing hydrogen and carbon dioxide through first and second reactors connected in series, wherein the first and second reactors each include a heating unit that heats the raw material gas to a temperature suitable for a methanation reaction, a reaction unit that methanates the raw material gas using a catalyst maintained at a temperature suitable for the methanation reaction, a cooling unit that cools a reaction gas generated from the raw material gas by the methanation reaction to a temperature at which water is condensed from the reaction gas, and a heat transfer medium flow path that is disposed in a state surrounding the heating unit, the reaction unit, and the cooling unit and is a flow path through which a heat transfer medium flows, The heating section, the reaction section, and the cooling section are arranged in this order, and the heat medium in a first temperature zone supplied to the heat medium flow path moves within the heat medium flow path, passing through a region corresponding to the cooling section, a region corresponding to the reaction section, and a region corresponding to the heating section, in that order. As it passes through the region corresponding to the cooling section, it exchanges heat with the reaction gas and becomes a second temperature zone higher than the first temperature zone. As it passes through the region corresponding to the reaction section, it exchanges heat with the catalyst and becomes a third temperature zone higher than the second temperature zone. As it passes through the region corresponding to the heating section, it exchanges heat with the raw material gas and becomes a fourth temperature zone lower than the third temperature zone and higher than the first temperature zone.
[0007] The above-described methane production apparatus, with such a configuration, heats the raw material gas and prevents the occurrence of a catalyst region in a temperature range unsuitable for reaction in the methanation catalyst with which the raw material gas comes into contact in the first reactor and the second reactor, thereby enabling the above-described methane production apparatus to reduce the amount of methanation catalyst.
[0008] In the methane production apparatus of the present disclosure, the first and second reactors are each arranged to surround the heating unit, and further include a separate heat medium flow path through which a separate heat medium other than the heat medium flows. The separate heat medium supplied to the separate heat medium flow path moves within the heat medium flow path to pass through a region corresponding to the heating unit, and heats the feed gas while passing through the region corresponding to the heating unit. The methane production apparatus further includes a separate heat medium supplying unit that supplies the separate heat medium to the separate heat medium flow path until a methanation reaction of the feed gas becomes stable, and a heat medium supplying unit that supplies the heat medium in the first temperature range to the heat medium flow path after the methanation reaction of the feed gas becomes stable.
[0009] The methane production apparatus described above can also achieve time savings and energy savings due to such a configuration.
[0010] In addition, in the methane production apparatus of the present disclosure, the first and second reactors each include a conductor unit arranged to surround the heating unit, and the methane production apparatus further includes a heater circuit that heats the raw material gas via the conductor unit until the methanation reaction of the raw material gas becomes stable, and a heat medium supply unit that supplies the heat medium in the first temperature range to the heat medium flow path after the methanation reaction of the raw material gas becomes stable.
[0011] The methane production apparatus described above can also achieve time savings and energy savings due to such a configuration.
[0012] In addition, the methane production apparatus of the present disclosure further includes a raw material gas supply source that controls the supply amount of the raw material gas so that the methane conversion rate converted in the first reactor is higher than the methane conversion rate converted in the second reactor.
[0013] The methane production apparatus described above can produce methane efficiently with such a configuration. [Effects of the Invention]
[0014] According to the present disclosure, it is possible to provide a methane production apparatus that can reduce the amount of methanation catalyst used. [Brief explanation of the drawings]
[0015] [Figure 1] 1 is a diagram showing an example of the configuration of a methane production apparatus according to a first embodiment. [Figure 2] FIG. 4 is a diagram showing an example of the configuration of a methane production apparatus according to a second embodiment. [Figure 3] FIG. 10 is a diagram showing an example of the configuration of a methane production apparatus according to a third embodiment. [Figure 4] FIG. 10 is a diagram showing an example of the configuration of a methane production apparatus according to a fourth embodiment. [Figure 5] FIG. 10 is a diagram showing an example of the configuration of a methane production apparatus according to a fifth embodiment. [Figure 6] FIG. 10 is a diagram showing an example of the configuration of a methane production apparatus according to a sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION
[0016] (First embodiment) First, the configuration of a methane production apparatus 1 according to the first embodiment will be described with reference to FIG. Fig. 1 is a diagram showing an example of the configuration of a methane production apparatus 1 according to a first embodiment. As shown in Fig. 1, the methane production apparatus 1 is an apparatus that produces methane (CH4) from hydrogen (H2) and carbon dioxide (CO2). The methane production apparatus 1 includes a first reactor 10, a second reactor 20, a carbon dioxide supply source 30, a flow meter 31, hydrogen supply sources 40, 50, mass flow controllers (MFCs) 41, 51, heat medium supply units 60, 70, flow rate control valves 61, 71, a separate heat medium supply unit 80, and an in-line heater 81.
[0017] The first reactor 10 includes an inner tube 11, an outer tube 12, a heat transfer medium passage 13, and an additional heat transfer medium passage 14. The inner tube 11 is a tube-shaped member and includes a gas inlet section 111, a heating section 112, a reaction section 113, a cooling section 114, a condensed water discharge section 115, and a gas outlet section 116. The inner tube 11 is provided with the heating section 112, the reaction section 113, and the cooling section 114 in this order.
[0018] The gas inlet 111 is provided at one end of the inner tube 11. A room temperature raw material gas (CO2 + 4H2 × α) is supplied to the gas inlet 111 via pipes from a carbon dioxide supply source 30 and a hydrogen supply source 40. In the first reactor 10, a methane conversion rate α (0.5<α<0.9) is set, and the amount of hydrogen supplied is also fixed.
[0019] The heating unit 112 heats the raw material gas to a temperature (preferably 150° C. to 200° C.) suitable for the methanation reaction in the raw material gas. The reaction section 113 is filled with a methanation catalyst that is maintained at a temperature (preferably 200°C to 300°C) suitable for the methanation reaction in the methanation catalyst. The reaction section 113 causes the raw material gas to undergo a methanation reaction using the methanation catalyst. The methanation catalyst is a metal such as Ru or Ni that has methanation catalytic properties. The methanation reaction is represented by the chemical formula CO2 + 4H2 → CH4 + 2H2O - 165KJ. The cooling unit 114 cools the reaction gas (CH4+H2O+CO2) generated from the raw material gas by the methanation reaction to a temperature (preferably room temperature (30°C)) at which water is condensed from the reaction gas.
[0020] The heating unit 112, the reaction unit 113, and the cooling unit 114 exchange heat with a heat medium, which will be described later. Therefore, the inner walls of the inner tube 11 corresponding to the heating unit 112, the reaction unit 113, and the cooling unit 114 are made of a material with high thermal conductivity, such as copper. In addition, the inner walls of the inner tube 11 corresponding to the heating unit 112, the reaction unit 113, and the cooling unit 114 have a mesh structure.
[0021] The condensed water discharge part 115 is provided at the other end of the inner tube 11. The condensed water discharge part 115 stores condensed water (H2O) at room temperature condensed from the reaction gas and discharges the stored condensed water. The gas outlet 116 is provided at the other end of the inner tube 11. The gas outlet 116 discharges a reaction mixture gas (CH4 + CO2), which is a gas obtained by removing water from the reaction gas. The discharged reaction mixture gas is supplied to the second reactor 20 via a pipe.
[0022] The outer tube 12 is a tube-shaped member that is disposed outside the inner tube 11 so as to surround the inner tube 11. The outer tube 12 is made of a heat insulating material and has a structure that blocks heat exchange between the outside and the inside by using heat insulating means including vacuum insulation.
[0023] The heat medium flow path 13 is a flow path through which a heat medium flows, and is provided between the inner tube 11 and the outer tube 12. In other words, the heat medium flow path 13 has an insulating structure. The heat medium flow path 13 is a flow path with a uniform width and a spiral structure. The heat medium is, for example, oil. The inlet of the heat medium flow path 13 is provided at the other end of the outer tube 12 so as to penetrate the outer tube 12. The outlet of the heat medium flow path 13 is provided at one end of the outer tube 12 so as to penetrate the outer tube 12. Specifically, the heat medium flow path 13 is arranged to surround the heating section 112, the reaction section 113, and the cooling section 114 of the inner tube 11.
[0024] During activation (start-up) operation until the methanation reaction in the reaction section 113 stabilizes, the heat medium is stopped in the heat medium flow path 13. Then, during normal operation after the methanation reaction in the reaction section 113 stabilizes, the heat medium is started to be supplied from the heat medium supply section 60 via a pipe at a first temperature zone (room temperature). The heat medium flows through the heat medium flow path 13, passing sequentially through a region corresponding to the cooling section 114, a region corresponding to the reaction section 113, and a region corresponding to the heating section 112. When the heat medium in the first temperature zone supplied to the heat medium flow path 13 passes through the region corresponding to the cooling section 114, it exchanges heat with the reactant gas and reaches a second temperature zone higher than the first temperature zone. Next, when the heat medium passes through the region corresponding to the reaction section 113, it exchanges heat with the methanation catalyst and reaches a third temperature zone higher than the second temperature zone. Next, when the heat medium passes through the region corresponding to the heating section 112, it exchanges heat with the feed gas and reaches a fourth temperature zone lower than the third temperature zone and higher than the first temperature zone. The heat-exchanged heat medium is then supplied to a heat utilization destination.
[0025] The separate heat medium flow path 14 is a flow path through which a heat medium (hereinafter referred to as the separate heat medium) different from the heat medium flowing through the heat medium flow path 13 flows, and is provided between the inner tube 11 and the outer tube 12. The separate heat medium flow path 14 is, for example, a flow path with a spiral structure. The separate heat medium flow path 14 is provided as a double spiral structure together with the heat medium flow path 13 between the inner tube 11 and the outer tube 12. Specifically, the separate heat medium flow path 14 is disposed so as to surround the heating section 112. The inlet and outlet of the separate heat medium flow path 14 are provided so as to penetrate the outer tube 12.
[0026] During activation operation, the other heat medium is supplied in a heated state from the other heat medium supply unit 80 via a pipe to the other heat medium flow path 14. The other heat medium exchanges heat with the raw material gas while passing through a region corresponding to the heating unit 112. The other heat medium after heat exchange is then supplied to the second reactor 20 via a pipe. During normal operation, the supply of the other heat medium from the other heat medium supply unit 80 is stopped, and the other heat medium is stopped in the other heat medium flow path 14.
[0027] The second reactor 20 also has a configuration similar to that of the first reactor 10. The second reactor 20 includes an inner tube 21, an outer tube 22, a heat transfer medium flow path 23, and another heat transfer medium flow path 24. The inner tube 21 includes a gas inlet section 211, a heating section 212, a reaction section 213, a cooling section 214, a condensed water discharge section 215, and a gas outlet section 216.
[0028] The inner tube 21, the outer tube 22, the heat transfer medium passage 23, and the separate heat transfer medium passage 24 of the second reactor 20 correspond to the inner tube 11, the outer tube 12, the heat transfer medium passage 13, and the separate heat transfer medium passage 14 of the first reactor 10, respectively. Furthermore, the gas inlet section 211, the heating section 212, the reaction section 213, the cooling section 214, the condensed water discharge section 215, and the gas outlet section 216 of the second reactor 20 correspond to the gas inlet section 111, the heating section 112, the reaction section 113, the cooling section 114, the condensed water discharge section 115, and the gas outlet section 116 of the first reactor 10, respectively.
[0029] Here, in the second reactor 20, a room temperature reaction mixed gas (CH4 + CO2) is supplied to the gas inlet 211 from the first reactor 10 via a pipe. In addition, a room temperature raw material gas (4H2 × (1-α)) is supplied to the gas inlet 211 from the hydrogen supply source 50 via a pipe. In the second reactor 20, a methane conversion rate (1-α) (0.1<(1-α)<0.5) is set. Furthermore, in the second reactor 20, methane gas (CH4) obtained by removing water from the reaction gas is discharged from the gas outlet 216. The discharged methane gas is supplied to a destination for using the methane via a pipe. In the second reactor 20, the other heat medium is supplied from the first reactor 10 to the other heat medium flow path 24 via a pipe. The other heat medium exchanges heat with the raw material gas while passing through a region corresponding to the heating unit 212. Thereafter, the other heat medium after heat exchange is returned to the other heat medium supply unit 80 via a pipe.
[0030] The carbon dioxide supply source 30 is a supply source capable of supplying a raw material gas containing carbon dioxide. Furthermore, the flow meter 31 measures the flow rate of the raw material gas containing carbon dioxide supplied from the carbon dioxide supply source 30. The hydrogen supply sources 40, 50 are supply sources capable of supplying a raw material gas containing hydrogen. Here, the carbon dioxide supply source 30 and the hydrogen supply sources 40, 50 are collectively referred to as raw material gas supply sources. The MFCs 41, 51 adjust the amount of the raw material gas containing hydrogen supplied from the hydrogen supply sources 40, 50, respectively. The raw material gas containing carbon dioxide supplied from the carbon dioxide supply source 30 and hydrogen supplied from the hydrogen supply source 40 is supplied to the first reactor 10 via piping. Furthermore, the raw material gas containing hydrogen supplied from the hydrogen supply source 50 is supplied to the second reactor 20 via piping.
[0031] The heat medium supplying units 60, 70 are parts capable of supplying a heat medium. The heat medium supplying units 60, 70 are configured, for example, by oil pumps. The heat medium supplied from the heat medium supplying unit 60 is supplied to the first reactor 10 via piping, and then supplied to the heat utilization destination. The heat medium supplied from the heat medium supplying unit 70 is supplied to the second reactor 20 via piping, and then supplied to the heat utilization destination. Here, the heat medium supplying units 60, 70 supply the heat medium after the methanation reaction is initiated by activation of the first reactor 10 and the second reactor 20 by the separate heat medium supplying unit 80. The flow rate control valves 61, 71 adjust the flow rate of the heat medium supplied from the heat medium supplying units 60, 70, respectively. Specifically, the first reactor 10 is provided with a thermocouple that measures the temperature T1 inside the inner tube 11. In particular, the first reactor 10 is provided with a thermocouple that measures the temperature T1 of the raw material gas. in , temperatures of the methanation catalyst T11, T12, T13, and the reaction gas temperature T1 out , are provided. The flow rate control valve 61 adjusts the flow rate of the heat medium based on the measurement result of the temperature T1. Furthermore, the second reactor 20 is provided with a thermocouple that measures the temperature T2 inside the inner tube 21. In detail, the second reactor 20 is provided with a thermocouple that measures the temperature T2 of the raw material gas. in , temperatures of the methanation catalyst T21, T22, T23, and the reaction gas temperature T2 out, and a thermocouple is provided to measure each of the temperature T1 and the temperature T2. The flow rate control valve 71 adjusts the flow rate of the heat medium based on the measurement result of the temperature T2. n The number of thermocouples measuring the temperature T2 of the methanation catalyst in the second reactor 20 n The number of thermocouples for measuring the temperatures T11, T12, and T13 of the methanation catalyst may be replaced by a thermocouple for measuring the representative temperature T1 of the methanation catalyst in the first reactor 10. The same applies to the second reactor 20.
[0032] The separate heat medium supply unit 80 is a portion capable of supplying the separate heat medium. The separate heat medium supply unit 80 is configured, for example, by an oil pump. The in-line heater 81 heats the separate heat medium supplied from the separate heat medium supply unit 80 to a predetermined temperature (preferably 250 to 300°C). The separate heat medium supplied from the separate heat medium supply unit 80 is supplied to the first reactor 10 via piping. The separate heat medium supply unit 80 supplies the separate heat medium during activation of the methanation reaction in the first reactor 10 and the second reactor 20. Then, the separate heat medium supply unit 80 stops supplying the separate heat medium after activation is completed.
[0033] Furthermore, in the first reactor 10 described above, the amount of heat generated in the first reactor 10 can be predicted based on the set value α of the methane conversion rate. At the same time, the temperature of the reaction gas discharged through the reaction section 113 is also predicted by simulation. The heat transfer configuration (e.g., heat transfer area) of the cooling section 114 is calculated based on the amount of heat generated in the first reactor 10 and the temperature of the reaction gas discharged through the reaction section 113. Furthermore, the temperature of the heat medium after heat exchange in the heating section 112 can also be predicted. The heat transfer configuration of the heating section 112 is calculated based on the predicted heat medium temperature.
[0034] In the second reactor 20, the amount of reaction heat can be predicted by adding hydrogen according to the methane conversion rate (1-α) to cause a methanation reaction. The heat transfer configuration of the heating section 212 and the cooling section 214 is designed based on the amount of reaction heat. In addition, the amount of methanation catalyst in the second reactor 20 is determined taking into account the amount of methane produced in the first reactor 10, which acts as a reaction inhibitor.
[0035] The methane production system 1 performs activation in the same way in both the first reactor 10 and the second reactor 20. Once the methanation reaction has stabilized, the methane production system 1 stops the inflow of the separate heat medium for activation. In the methane production system 1, a separate heat medium is selected that can start the reaction stably and in a short time with the minimum required thermal energy, and the heat transfer configuration of the heat exchange in both the first reactor 10 and the second reactor 20 is appropriately designed.
[0036] Next, the operation of the methane production apparatus 1 according to the first embodiment will be described with reference to Fig. 1. In the following, the operation in the first reactor 10 of the methane production apparatus 1 will be mainly described, but the operation in the second reactor 20 is also similar to the operation in the first reactor 10. <Activation behavior> First, the carbon dioxide supply source 30 and the hydrogen supply source 40 supply a room temperature raw material gas containing carbon dioxide in an amount to be treated and hydrogen in an amount corresponding to the methane conversion rate α to the gas inlet 111 of the first reactor 10. The separate heat medium supply unit 80 supplies the separate heat medium heated to a predetermined temperature (preferably 250 to 300°C) by the in-line heater 81 to the separate heat medium flow path 14 of the first reactor 10. When the supply of the separate heat medium starts, the flow of the heat medium in the heat medium flow path 13 of the first reactor 10 is stopped, and the temperature of the heat medium is room temperature (30°C). The supplied separate heat medium passes through a region corresponding to the heating unit 112 of the first reactor 10 and exchanges heat with the raw material gas as it passes. The raw material gas that has exchanged heat with the separate heat medium is heated to an appropriate temperature (preferably about 150 to 200°C). When the heated raw material gas comes into contact with the methanation catalyst in the reaction section 113, the temperature immediately becomes suitable for the reaction, and the methanation reaction begins.
[0037] <Normal operation> Next, in the reaction section 113 of the first reactor 10, a methanation reaction is initiated near the inlet of the methanation catalyst. Thereafter, the reaction heat of the methanation reaction in the reaction section 113 heats the heat medium whose flow has stopped in the heat medium flow path 13, and the heat transfer in the heat medium and the heat transport by the reaction gas cause the downstream methanation catalyst to reach an optimum reaction temperature in a chain reaction. This initiates the methanation reaction of the raw material gas over the entire methanation catalyst. After the methanation reaction has started, the heat medium supply section 60 starts supplying the heat medium to the heat medium flow path 13 of the first reactor 10. Here, the flow rate control valve 61 controls the temperature inside the inner tube 11 (the temperature of the raw material gas (T1 in ), the temperature of the methanation catalyst (T11, T12, T13), the temperature of the reaction gas (T1 out )) and controls the flow rate of the heat medium supplied to the first reactor 10. When the methanation reaction is stable, even if the supply of the separate heat medium for activation operation from the separate heat medium supply unit 80 is stopped, the methanation reaction continues due to the reaction heat of the first reactor 10 itself.
[0038] <Heat transfer medium action> The room-temperature (30°C) heat medium supplied from the heat medium supply unit 60 to the heat medium flow path 13 moves to the region corresponding to the cooling unit 114 and exchanges heat with the high-temperature (150°C) reactant gas in the cooling unit 114. The reactant gas is cooled to about 30°C. Meanwhile, the heat medium is heated to about 80 to 100°C. As a result, condensed water is separated from the reactant gas. Next, the heated heat medium moves to the region corresponding to the reaction unit 113 and removes the reaction heat of the methanation reaction of the raw material gas in the reaction unit 113, maintaining the temperature of the filled methanation catalyst at 200 to 300°C. Meanwhile, the heat medium is heated to about 180°C. Next, the heated heat medium moves to the region corresponding to the heating unit 112 and exchanges heat with the raw material gas in the heating unit 112. At this time, the raw material gas is heated from room temperature (30°C) to 150°C. Meanwhile, the heat transfer medium is cooled from about 180°C to about 120°C. The heat transfer medium is then discharged outside the first reactor 10 and supplied to the heat utilization destination. In this way, the first reactor 10 is structured to be able to continuously transfer the necessary heat using a room-temperature heat transfer medium without inputting external energy. The reaction mixture gas discharged from the first reactor 10 contains unreacted carbon dioxide (CO2) as well as a large amount of methane (CH4). Furthermore, because this reaction mixture gas is at room temperature, there is no temperature difference with the outside, and heat energy is not lost through heat radiation.
[0039] <Feedstock gas management> In the first reactor 10, a methane conversion rate α of the methanation reaction is set. Because methane acts as an inhibitor of the methanation reaction in the second reactor 20, α is preferably set between 0.55 and 0.85 so that the methane conversion rate α of the first reactor 10 is higher than the methane conversion rate 1-α of the second reactor 20. For example, when α is set to 0.8, 80% of the produced methane (CH4) and 20% of unreacted carbon dioxide (CO2) remain at the outlet of the first reactor 10 after the condensed water is removed. Then, the remaining 20% of hydrogen is further supplied at the inlet of the second reactor 20, achieving a methane conversion rate of 98% or more.
[0040] As described above, the methane production apparatus 1 of the present disclosure has a configuration that allows it to have the following functions simply by supplying the heat medium at room temperature to the first reactor 10 and the second reactor 20 without external energy: (1) The ability to remove condensed water from the reaction gas. Here, because the water removed is at room temperature, thermal energy is not lost to the outside, such as through heat radiation. (2) The ability to maintain the temperature of the methanation catalyst at an appropriate temperature (preferably 200 to 300°C). (3) The ability to reduce the amount of methanation catalyst by heating the feed gas to an appropriate temperature (preferably 100 to 150°C) and supplying it to the methanation catalyst. Furthermore, because the above configuration can be implemented within an insulated structure, the methane production apparatus 1 can utilize all of the thermal energy of the methanation reaction, which is an exothermic reaction. Since the heat medium temperature remains high even after discharge, the heat can be utilized in another process.
[0041] Here, the methane production apparatus 1 is configured to control the amount of heat medium supplied by controlling the amount of heat medium supplied using the temperature T1 in the first reactor 10 and the temperature T2 in the second reactor 20. Therefore, the methane production apparatus 1 can maintain the temperature of the methanation catalyst at an appropriate temperature.
[0042] Furthermore, the methane production apparatus 1 is configured to heat the raw material gas to an appropriate temperature using a separate heat medium circuit to activate the methanation reaction, which allows the methane production apparatus 1 to reduce time and energy consumption. Furthermore, in the first reactor 10 of the methane production apparatus 1, a methane conversion rate α (0.5<α<0.9) is set, and the amount of hydrogen supplied is fixed. In the first reactor 10, necessary and sufficient heat transfer is designed for the heating section 112 and the cooling section 114 based on a thermal energy prediction corresponding to the methane conversion rate α. In the second reactor 20, a methane conversion rate (1-α) (0.1<(1-α)<0.5) is set, and the amount of hydrogen supplied is fixed. In the second reactor 20, necessary and sufficient heat transfer is designed for the heating section 212 and the cooling section 214 based on a thermal energy prediction corresponding to the methane conversion rate.
[0043] (Second embodiment) Next, the configuration of the methane production apparatus 2 according to the second embodiment will be described with reference to Fig. 2. Fig. 2 is a diagram showing an example of the configuration of the methane production apparatus 2 according to the second embodiment. As shown in FIG. 2 , the methane production apparatus 2 has the following configuration compared to the methane production apparatus 1 according to the first embodiment. The methane production apparatus 2 does not use a separate heat medium flowing through a separate heat medium flow path 14 for the activation operation of the first reactor 10, but instead uses a sheath heater circuit (heater circuit) 15 in which a conductor portion is heated to a predetermined temperature (preferably 250 to 300°C) by a sheath heater (heater). That is, the methane production apparatus 2 does not include a separate heat medium supply unit 80 or an in-line heater 81. The first reactor 10 of the methane production apparatus 2 does not include a separate heat medium flow path 14. The conductor portion of the sheath heater circuit 15 is disposed in a region corresponding to the heating portion 112 between the inner tube 11 and the outer tube 12 of the first reactor 10, surrounding the heating portion 112, and is provided as a double spiral structure together with the heat medium flow path 13. The second reactor 20 of the methane production apparatus 2 also has a configuration similar to that of the first reactor 10. The sheath heater circuit 25 of the second reactor 20 corresponds to the sheath heater circuit 15 of the first reactor 10 .
[0044] (Third embodiment) Next, the configuration of the methane production apparatus 3 according to the third embodiment will be described with reference to Fig. 3. Fig. 3 is a diagram showing an example of the configuration of the methane production apparatus 3 according to the third embodiment. As shown in FIG. 3 , the methane production apparatus 3 has the following configuration to increase the processing capacity of the methanation reaction compared to the methane production apparatus 1 according to the first embodiment. The first reactor 10 of the methane production apparatus 3 has a shell-and-tube structure in a region corresponding to a reaction section 113 where the raw material gas is methanated using a methanation catalyst. Specifically, the inner tube 11 of the first reactor 10 includes a plurality of tubes 16n, each including a reaction section 113n (n is a natural number). The inner tube 11 has a shell structure surrounding the plurality of tubes 16n. The inner tube 11 also has a chamber structure near the inlet and outlet of the tube 16n to stabilize the flow rate of the raw material gas around the tube 16n. For example, a heating section 112 and a cooling section 114 are provided in the chamber portion of the inner tube 11. The second reactor 20 of the methane production apparatus 3 also has a configuration similar to that of the first reactor 10. The tubes 26n of the second reactor 20 correspond to the tubes 16n of the first reactor 10.
[0045] (Fourth embodiment) Next, the configuration of the methane production apparatus 4 according to the fourth embodiment will be described with reference to Fig. 4. Fig. 4 is a diagram showing an example of the configuration of the methane production apparatus 4 according to the fourth embodiment. As shown in FIG. 4, the methane production apparatus 4 has the following configuration to increase the processing capacity of the methanation reaction compared to the methane production apparatus 1 according to the first embodiment. The first reactor 10 of the methane production apparatus 4 has a multi-tube double-tube structure in a region corresponding to the reaction section 113 where the raw material gas is methanated using a methanation catalyst. Specifically, the inner tube 11 of the first reactor 10 includes a plurality of tubes 17n including a heating section 112n, a reaction section 113n, and a cooling section 114n. Here, in the first reactor 10, the heat transfer medium flow path 13 and the separate heat transfer medium flow path 14 are arranged to surround each of the tubes 17n. The second reactor 20 of the methane production apparatus 3 also has a configuration similar to that of the first reactor 10. The tubes 27n of the second reactor 20 correspond to the tubes 17n of the first reactor 10.
[0046] (Fifth embodiment) Next, the configuration of the methane production apparatus 5 according to the fifth embodiment will be described with reference to Fig. 5. Fig. 5 is a diagram showing an example of the configuration of the methane production apparatus 5 according to the fifth embodiment. As shown in Fig. 5, the methane production apparatus 5 has the following configuration compared to the methane production apparatus 3 according to the third embodiment. The methane production apparatus 5 does not use a separate heat medium flowing through a separate heat medium flow path 14 for the activation operation of the first reactor 10, but uses a sheath heater circuit 15 that heats the conductor portion to a predetermined temperature (preferably 250 to 300°C). The second reactor 20 of the methane production apparatus 5 also has the same configuration as the first reactor 10. The sheath heater circuit 25 of the second reactor 20 corresponds to the sheath heater circuit 15 of the first reactor 10.
[0047] (Sixth embodiment) Next, the configuration of the methane production apparatus 6 according to the sixth embodiment will be described with reference to Fig. 6. Fig. 6 is a diagram showing an example of the configuration of the methane production apparatus 6 according to the sixth embodiment. As shown in Fig. 6, the methane production apparatus 6 has the following configuration compared to the methane production apparatus 4 according to the fourth embodiment. The methane production apparatus 6 does not use a separate heat medium flowing through a separate heat medium flow path 14 for the activation operation of the first reactor 10, but uses a sheath heater circuit 15 that heats the conductor portion to a predetermined temperature (preferably 250 to 300°C). The second reactor 20 of the methane production apparatus 6 also has the same configuration as the first reactor 10. The sheath heater circuit 25 of the second reactor 20 corresponds to the sheath heater circuit 15 of the first reactor 10.
[0048] The present invention is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the invention. [Explanation of symbols]
[0049] 1 to 6 methane production apparatus, 10 first reactor, 11 inner tube, 12 outer tube, 13 heat transfer medium flow path, 14 separate heat transfer medium flow path, 15 sheathed heater circuit (heater circuit), 16n tube, 17n tube, 20 second reactor, 21 inner tube, 22 outer tube, 23 heat transfer medium flow path, 24 separate heat transfer medium flow path, 25 sheathed heater circuit, 26n tube, 27n tube, 30 carbon dioxide supply source, 31 flow meter, 40, 50 hydrogen supply source, 41, 51 mass flow controller (MFC), 60, 70 heat transfer medium supply section, 61, 71 flow control valve, 80 separate heat transfer medium supply section, 81 in-line heater, 111, 211 gas inlet section, 112, 112n, 212, 212n Heating section, 113, 113n, 213, 213n Reaction section, 114, 114n, 214, 214n Cooling section, 115, 215 Condensate discharge section, 116, 216 Gas outlet section
Claims
1. A methane production apparatus that produces methane by passing a raw material gas containing hydrogen and carbon dioxide through first and second reactors connected in series, The first and second reactors each comprise: a heating unit that heats the raw material gas to a temperature suitable for a methanation reaction; a reaction section for causing a methanation reaction of the raw material gas using a catalyst maintained at a temperature suitable for the methanation reaction; a cooling unit that cools a reaction gas generated from the raw material gas by a methanation reaction to a temperature at which water is condensed from the reaction gas; a heat transfer medium flow path that is a flow path through which a heat transfer medium flows, and that is arranged in a state surrounding the heating unit, the reaction unit, and the cooling unit, the heating section, the reaction section, and the cooling section are arranged in this order; The heat medium in the first temperature range supplied to the heat medium flow path is The heat transfer medium moves through the heat transfer passage so as to pass through a region corresponding to the cooling unit, a region corresponding to the reaction unit, and a region corresponding to the heating unit in this order. When passing through the region corresponding to the cooling unit, the heat transfer medium exchanges heat with the reaction gas and reaches a second temperature zone higher than the first temperature zone. When passing through the region corresponding to the reaction unit, the heat transfer medium exchanges heat with the catalyst and reaches a third temperature zone higher than the second temperature zone. When passing through the region corresponding to the heating unit, the heat transfer medium exchanges heat with the raw material gas and reaches a fourth temperature zone lower than the third temperature zone and higher than the first temperature zone. Methane production equipment.
2. The first and second reactors each comprise: The heating unit further includes a separate heat medium flow path that is a flow path through which a separate heat medium flows, the separate heat medium flow path being arranged to surround the heating unit, the separate heat medium supplied to the separate heat medium flow path moves through the heat medium flow path to pass through a region corresponding to the heating unit, and heats the raw material gas while passing through the region corresponding to the heating unit; The methane production apparatus comprises: an additional heat medium supply unit that supplies the additional heat medium to the additional heat medium flow path until the methanation reaction of the raw material gas becomes stable; a heat medium supply unit that supplies the heat medium in the first temperature range to the heat medium flow path after the methanation reaction of the raw material gas has stabilized. The methane production apparatus according to claim 1 .
3. The first and second reactors each comprise: a conductor portion disposed in a state surrounding the heating portion, The methane production apparatus comprises: a heater circuit that heats the raw material gas through the conductor portion until the methanation reaction of the raw material gas becomes stable; a heat medium supply unit that supplies the heat medium in the first temperature range to the heat medium flow path after the methanation reaction of the raw material gas has stabilized. The methane production apparatus according to claim 1 .
4. The reactor further includes a raw material gas supply source that controls the supply amount of the raw material gas so that the methane conversion rate converted in the first reactor is higher than the methane conversion rate converted in the second reactor. The methane production apparatus according to claim 1 .