Methane producing apparatus

Abstract

To provide a methane producing apparatus that can reduce an amount of methanation catalyst.SOLUTION: A methane producing apparatus 1 produces methane by allowing raw material gas to pass through a first reactor 10 and a second reactor 20. Each reactor comprises: a heating part 112 which heats raw material gas to an optimal temperature; a reaction part 113 which allows raw material gas to perform methanation reaction by a catalyst maintained at an optimal temperature; a cooling part 114 which cools reaction gas; and a heat medium flow channel 13 which is a flow channel arranged in a state of surrounding the parts, and through which heat medium is flown. A heat medium in a first temperature zone which has been supplied to the heat medium flow channel performs heat exchange with reaction gas of the cooling part 114 to enter a second temperature zone higher than the first temperature zone, performs heat exchange with a catalyst of the reaction part 113 to enter a third temperature zone higher than the second temperature zone, and performs heat exchange with raw material gas of the heating part 112 to enter a fourth temperature zone lower than the third temperature zone and higher than the first temperature zone.SELECTED DRAWING: Figure 1

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] JP 2020-083799 A 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 fed into the first reactor, and reaction gas cooled to room temperature to remove condensed water is fed into the second reactor, so that the methanation catalyst with which the raw material gas comes into contact in the first and second reactors generates a catalyst region with a temperature range unsuitable for reaction. The technology disclosed in Patent Document 1 has a problem in that it uses more expensive methanation catalyst than necessary.

[0005] In view of such problems, the present disclosure aims to provide a methane production apparatus capable of reducing the amount of methanation catalyst. [Means for solving the problem]

[0006] The methane production apparatus of the present disclosure is 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, 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 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 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 to pass through, in order, a region corresponding to the cooling section, a region corresponding to the reaction section, and a region corresponding to the heating section. When passing through the region corresponding to the cooling section, the heat medium exchanges heat with the reaction gas and becomes a second temperature zone higher than the first temperature zone, and when passing through the region corresponding to the reaction section, the heat medium exchanges heat with the catalyst and becomes a third temperature zone higher than the second temperature zone. When passing through the region corresponding to the heating section, the heat medium 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-mentioned 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, and therefore the amount of the methanation catalyst can be reduced.

[0008] In the methane production apparatus of the present disclosure, the first and second reactors are each arranged in a state surrounding the heating unit, and further include a separate heat medium flow path that is a flow path through which a separate heat medium other than the heat medium flows, and the separate heat medium supplied to the separate heat medium flow path moves within the heat medium flow path so as to pass through a region corresponding to the heating unit, and heats the raw material gas when passing through the region corresponding to the heating unit, and 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 raw material gas becomes stable, and a heat medium supplying unit that supplies the heat medium in the first temperature zone to the heat medium flow path after the methanation reaction of the raw material gas becomes stable.

[0009] With such a configuration, the above-mentioned methane production apparatus can also achieve time savings and energy savings.

[0010] In the methane production apparatus of the present disclosure, the first and second reactors each include a conductor section arranged to surround the heating section, and the methane production apparatus further includes a heater circuit that heats the raw material gas via the conductor section until the methanation reaction of the raw material gas becomes stable, and a heat medium supplying section that supplies the heat medium in the first temperature zone to the heat medium flow path after the methanation reaction of the raw material gas becomes stable.

[0011] With such a configuration, the above-mentioned methane production apparatus can also achieve time savings and energy savings.

[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] With such a configuration, the above-mentioned methane production apparatus can efficiently produce methane. Effect of the Invention

[0014] According to the present disclosure, it is possible to provide a methane production apparatus capable of reducing the amount of methanation catalyst. [Brief description 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. [Diagram 2] FIG. 4 is a diagram showing an example of the configuration of a methane production apparatus according to a second embodiment. [Diagram 3] FIG. 11 is a diagram showing an example of the configuration of a methane production apparatus according to a third embodiment. [Figure 4] FIG. 11 is a diagram showing an example of the configuration of a methane production apparatus according to a fourth embodiment. [Diagram 5] FIG. 13 is a diagram showing an example of the configuration of a methane production apparatus according to a fifth embodiment. [Figure 6] FIG. 13 is a diagram showing an example of the configuration of a methane production apparatus according to a sixth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 for producing 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, another 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 a separate heat transfer medium passage 14. The inner tube 11 is a tube-shaped member. The inner tube 11 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 heating section 112, the reaction section 113, and the cooling section 114 are provided in this order in the inner tube 11.

[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 through piping 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 kept 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 by the methanation catalyst. The methanation catalyst is, for example, a metal having methanation catalytic properties such as Ru or Ni. 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 by the methanation reaction from the raw material gas 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 mixed gas (CH4+CO2) which is a gas obtained by removing water from the reaction gas. The discharged reaction mixed gas is supplied to the second reactor 20 via a pipe.

[0022] The outer tube 12 is a tube-shaped member, and 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 the heat medium flows, and is provided between the inner tube 11 and the outer tube 12. That is, the heat medium flow path 13 has a heat 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 in a state surrounding 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 becomes stable, the heat medium is stopped in the heat medium flow passage 13. Then, during normal operation after the methanation reaction in the reaction section 113 becomes stable, the heat medium is started to be supplied from the heat medium supply section 60 through the piping in the first temperature zone (room temperature). The heat medium flows in the heat medium flow passage 13 so as to pass through the area corresponding to the cooling section 114, the area corresponding to the reaction section 113, and the area corresponding to the heating section 112 in order. When passing through the area corresponding to the cooling section 114, the heat medium in the first temperature zone supplied to the heat medium flow passage 13 exchanges heat with the reaction gas and becomes a second temperature zone higher than the first temperature zone. Next, when passing through the area corresponding to the reaction section 113, the heat medium exchanges heat with the methanation catalyst and becomes a third temperature zone higher than the second temperature zone. Next, when passing through the area corresponding to the heating section 112, the heat medium 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. Thereafter, the heat-exchanged heat medium is supplied to a heat utilization destination.

[0025] The separate heat medium flow path 14 is a flow path through which a heat medium (hereinafter, the separate heat medium) other than 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 having 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 the outlet of the separate heat medium flow path 14 are provided so as to penetrate the outer tube 12.

[0026] During activation operation, the separate heat medium is supplied in a heated state from the separate heat medium supply unit 80 through a pipe to the separate heat medium flow path 14. The separate heat medium exchanges heat with the raw material gas when passing through a region corresponding to the heating unit 112. The separate heat medium after heat exchange is then supplied to the second reactor 20 through a pipe. During normal operation, the supply of the separate heat medium from the separate heat medium supply unit 80 is stopped, and the separate heat medium stops in the separate heat medium flow path 14.

[0027] The second reactor 20 has the same configuration as the first reactor 10. The second reactor 20 includes an inner tube 21, an outer tube 22, a heat medium passage 23, and a separate heat medium passage 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 medium passage 23 and the separate heat medium passage 24 of the second reactor 20 correspond to the inner tube 11, the outer tube 12, the heat medium passage 13 and the separate heat medium passage 14 of the first reactor 10, respectively. Moreover, 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 mixture 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. In the second reactor 20, the gas outlet 216 discharges methane gas (CH4) obtained by removing water from the reaction gas. The discharged methane gas is supplied to a destination of use of the methane via a pipe. In the second reactor 20, the separate heat medium is supplied from the first reactor 10 to the separate heat medium flow path 24 via a pipe. The separate heat medium exchanges heat with the raw material gas when passing through a region corresponding to the heating section 212. Thereafter, the separate heat medium after the heat exchange is returned to the separate heat medium supply section 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. 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 and 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 and 50 are collectively referred to as raw material gas supply sources. The MFCs 41 and 51 adjust the amount of the raw material gas containing hydrogen supplied from the hydrogen supply sources 40 and 50, respectively. The raw material gas containing carbon dioxide supplied from the carbon dioxide supply source 30 and the hydrogen supplied from the hydrogen supply source 40 are supplied to the first reactor 10 via a pipe. The raw material gas containing hydrogen supplied from the hydrogen supply source 50 is supplied to the second reactor 20 via a pipe.

[0031] The heat medium supplying units 60 and 70 are parts capable of supplying a heat medium. The heat medium supplying units 60 and 70 are, for example, composed of an oil pump. The heat medium supplied from the heat medium supplying unit 60 is supplied to the first reactor 10 through a pipe, 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 through a pipe, and then supplied to the heat utilization destination. Here, the heat medium supplying units 60 and 70 supply the heat medium after the methanation reaction is started by the 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 and 71 respectively adjust the flow rate of the heat medium supplied from the heat medium supplying units 60 and 70. Specifically, the first reactor 10 is provided with a thermocouple for measuring the temperature T1 inside the inner tube 11. In particular, the first reactor 10 is provided with a temperature T1 of the raw material gas. in , temperatures of the methanation catalyst T11, T12, T13, and temperature of the reaction gas 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. Also, the second reactor 20 is provided with a thermocouple that measures the temperature T2 inside the inner tube 21. In particular, 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 temperature of the reaction gas T2 out, and a thermocouple is provided to measure each of the above. 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 supplying unit 80 is a portion capable of supplying the separate heat medium. The separate heat medium supplying unit 80 is composed of, for example, an oil pump. The in-line heater 81 heats the separate heat medium supplied from the separate heat medium supplying unit 80 to a predetermined temperature (preferably 250 to 300°C). The separate heat medium supplied from the separate heat medium supplying unit 80 is supplied to the first reactor 10 via a pipe. The separate heat medium supplying 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 supplying unit 80 stops supplying the separate heat medium after the activation is completed.

[0033] Furthermore, in the above-mentioned first reactor 10, 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. In addition, 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 prediction of the heat medium temperature.

[0034] In the above-mentioned 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 consideration the amount of methane generated in the first reactor 10, which is a reaction inhibitor.

[0035] The methane production apparatus 1 performs activation operation in the same manner in both the first reactor 10 and the second reactor 20. When the methanation reaction starts to stabilize, the methane production apparatus 1 stops the inflow of the separate heat medium for activation. In the methane production apparatus 1, a separate heat medium that can start the reaction stably and in a short time with the minimum required thermal energy is selected, 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 operation, 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 Action> First, the carbon dioxide supply source 30 and the hydrogen supply source 40 supply a room temperature raw material gas containing the amount of carbon dioxide to be treated and the amount of hydrogen 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 when passing through. The raw material gas that has been heat exchanged 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 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 rear 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 is initiated, 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 )) is used to control 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 the 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 heat medium at room temperature (30°C) supplied from the heat medium supply unit 60 to the heat medium flow path 13 moves to a region corresponding to the cooling unit 114 and exchanges heat with the high-temperature (150°C) reaction gas in the cooling unit 114. The reaction gas is cooled to about 30°C. Meanwhile, the heat medium is heated to about 80 to 100°C. Therefore, condensed water is separated from the reaction gas. Next, the heated heat medium moves to a 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, and keeps 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 a 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 medium is cooled from about 180°C to about 120°C. Then, the heat medium is 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 cause the necessary heat transfer using a room temperature heat 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). In addition, since this reaction mixture gas is at room temperature, there is no temperature difference with the outside, and heat energy is not lost by heat radiation.

[0039] <Feedstock gas management> In the first reactor 10, a methane conversion rate α of the methanation reaction is set. Since methane is an inhibitor of the methanation reaction in the second reactor 20, it is preferable to set α 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=0.8 is set, 80% of the generated methane (CH4) and 20% of unreacted carbon dioxide (CO2) remain at the outlet of the first reactor 10 after removing the condensed water. Then, the remaining 20% ​​of hydrogen is further supplied at the inlet of the second reactor 20, and a methane conversion rate of 98% or more is achieved.

[0040] As described above, the methane production apparatus 1 of the present disclosure has a configuration that allows it to have the following functions by simply supplying the heat medium to the first reactor 10 and the second reactor 20 at room temperature without external energy. (1) A function of removing condensed water from the reaction gas. Here, since the water to be removed is at room temperature, thermal energy is not taken away to the outside, such as by heat radiation. (2) A function of maintaining the temperature of the methanation catalyst at an appropriate temperature (preferably 200 to 300°C). (3) A function of reducing the amount of methanation catalyst by heating the raw material gas to an appropriate temperature (preferably 100 to 150°C) and supplying it to the methanation catalyst. In addition, since the above configuration can be implemented within a heat-insulating structure, the methane production apparatus 1 can utilize all the thermal energy of the methanation reaction, which is an exothermic reaction, and since the temperature of the heat medium is high even after discharge, the heat can be utilized in another process.

[0041] Here, the methane production apparatus 1 has a configuration for controlling the amount of heat medium supplied by 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 by a separate heat medium circuit to activate the methanation reaction. Therefore, the methane production apparatus 1 can also reduce time and energy consumption. 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, a necessary and sufficient heat transfer design is performed 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, a necessary and sufficient heat transfer design is performed 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 another heat medium flowing through the other heat medium flow path 14 for the activation operation of the first reactor 10, but uses a sheath heater circuit (heater circuit) 15 in which a conductor part 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 have a separate heat medium supply part 80 and an in-line heater 81. In addition, the first reactor 10 of the methane production apparatus 2 does not have a separate heat medium flow path 14. The conductor part of the sheath heater circuit 15 is disposed in a state surrounding the heating part 112 in a region corresponding to the heating part 112 between the inner tube 11 and the outer tube 12 of the first reactor 10, and is provided as a double helix structure together with the heat medium flow path 13. In addition, the second reactor 20 of the methane production apparatus 2 also has a configuration similar to that of the first reactor 10. The sheathed heater circuit 25 of the second reactor 20 corresponds to the sheathed 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 for increasing the processing capacity of the methanation reaction, compared with 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 that causes a methanation reaction of the raw material gas by a methanation catalyst. Specifically, the inner tube 11 of the first reactor 10 has a plurality of tubes 16n including reaction sections 113n (n is a natural number). The inner tube 11 also has a shell structure so as to surround the plurality of tubes 16n. The inner tube 11 also has a chamber structure near the inlet and near the outlet of the tube 16n in order 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 for increasing the processing capacity of the methanation reaction, compared with 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 in which the raw material gas is subjected to a methanation reaction by 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 medium flow path 13 and the separate heat medium flow path 14 are arranged so as 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 uses a sheath heater circuit 15 in which the conductor portion is heated to a predetermined temperature (preferably 250 to 300°C) without using another heat medium flowing through the other heat medium flow path 14 for the activation operation of the first reactor 10. The second reactor 20 of the methane production apparatus 5 also has a similar configuration 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.

[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 uses a sheath heater circuit 15 in which the conductor portion is heated to a predetermined temperature (preferably 250 to 300° C.) without using another heat medium flowing through the other heat medium flow path 14 for the activation operation of the first reactor 10. The second reactor 20 of the methane production apparatus 6 also has a similar configuration to 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 without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0049] 1 to 6 methane production apparatus, 10 first reactor, 11 inner tube, 12 outer tube, 13 heat medium flow path, 14 separate heat medium flow path, 15 sheath heater circuit (heater circuit), 16n tube, 17n tube, 20 second reactor, 21 inner tube, 22 outer tube, 23 heat medium flow path, 24 separate heat medium flow path, 25 sheath 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 medium supply section, 61, 71 flow control valve, 80 separate heat 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 drain section, 116, 216 Gas outlet section

Claims

1. A methane production apparatus for producing 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 include: A heating unit that heats the raw material gas to a temperature suitable for a methanation reaction; a reaction section for carrying out a methanation reaction of the raw material gas by a catalyst maintained at a temperature suitable for the methanation reaction; a cooling unit that cools a reaction gas generated by a methanation reaction from the raw material gas to a temperature at which water is condensed from the reaction gas; a heat transfer medium flow path that is disposed in a state surrounding the heating unit, the reaction unit, and the cooling unit and through which a heat transfer medium flows; The heating section, the reaction section, and the cooling section are arranged in this order, The heat medium in the first temperature zone supplied to the heat medium flow path is The heat medium moves through the heat medium flow passage so as to pass through a region corresponding to the cooling section, a region corresponding to the reaction section, and a region corresponding to the heating section in this order. When passing through the region corresponding to the cooling section, the heat medium exchanges heat with the reaction gas and becomes a second temperature zone higher than the first temperature zone. When passing through the region corresponding to the reaction section, the heat medium exchanges heat with the catalyst and becomes a third temperature zone higher than the second temperature zone. When passing through the region corresponding to the heating section, the heat medium 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. Methane production equipment.

2. The first and second reactors each include: The heating unit is surrounded by a separate heat medium flow path through which a separate heat medium flows, the separate heat medium flow path being a flow path through which a separate heat medium flows, the separate heat medium supplied to the separate heat medium flow path moves in the heat medium flow path so as to pass through a region corresponding to the heating unit, and heats the raw material gas when 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 supplying 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 include: A conductive wire portion is disposed in a state surrounding the heating portion, The methane production apparatus comprises: a heater circuit for heating the raw material gas through the conductor portion until the methanation reaction of the raw material gas becomes stable; 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 raw material gas has stabilized. The methane production apparatus according to claim 1 .

4. The method further includes the step of: providing a raw material gas supply source that controls the supply amount of the raw material gas so that a conversion rate of methane converted in the first reactor is higher than a conversion rate of methane converted in the second reactor. The methane production apparatus according to claim 1 .

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