Methanation reaction apparatus and methanation reaction method

Abstract

To provide a methanation reactor capable of temperature control without relying on a heat transfer fluid system. [Solution] A methanation reaction apparatus 10 for generating a methanation reaction by bringing a raw material gas G1 into contact with a catalyst constituting a catalyst layer 32, comprising: a reaction tube body 14 arranged in the vertical axis direction and having an inner tube 14-1, an outer tube 14-2 arranged on the outer circumference of the inner tube, an internal space 15A between the outer tube 14-2 and the inner tube 14-1, and an internal space 15B inside the inner tube 14-1; a catalyst layer 32 formed in the internal space 15B; a raw material gas introduction line L1 for introducing the raw material gas from the lower end of the internal space 15A; a raw material gas discharge / inflow line L2 for discharging the raw material gas from the upper end of the internal space 15A to the outside of the reaction tube body 14, with the line end L2a connected to the upper end 14a of the inner tube; and a product gas discharge line for discharging the product gas G2 reacted in the catalyst layer from the lower end of the internal space 15B.

Description

[Technical Field]

[0001] This disclosure relates to a methanation reactor and a methanation reaction method. [Background technology]

[0002] In recent years, efforts have been made to reduce emissions and capture carbon dioxide, a greenhouse gas, in order to mitigate global warming. As one example of the use of captured carbon dioxide, as described in Patent Document 1, technologies related to methanation reactions, in which carbon dioxide and hydrogen are reacted to produce methane gas, are being developed.

[0003] Methanation is a reaction that primarily involves the reaction of carbon dioxide (CO2) with hydrogen (H2) on a catalyst to produce methane (CH4), as shown in the equation below. It is also known as the Sabatier reaction. CO2 + 4H2 → CH4 + 2H2O This reaction is often carried out under pressure conditions ranging from atmospheric pressure to 1.5 MPaG, and temperature conditions ranging from below 300°C to around 4-500°C.

[0004] Furthermore, systems utilizing the methanation reaction (methanation systems) typically consist of two or more reactors connected in series. The raw material gases (carbon dioxide and hydrogen) are first supplied to the first-stage reactor, where the outlet gas is cooled, and the resulting water condenses and undergoes gas-liquid separation. The gas, from which the water has been removed, is supplied to the second and subsequent reactors, where it undergoes the same process as the first-stage reactor. As a result, the final reactor outlet gas has a high conversion rate from carbon dioxide to methane, and the methane concentration is increased. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-040919 [Overview of the project] [Problems that the invention aims to solve]

[0006] The methanation reaction is an exothermic reaction accompanied by a reaction heat of 165.0 kJ / mol. Generally, once the reaction starts, the temperature of the catalyst layer in the reactor rises rapidly, raising concerns about catalyst degradation due to heat. Therefore, to control the temperature of the catalyst layer, a system is often employed in which the reactor is a heat exchanger type and a heat transfer medium (heat transfer oil) is circulated in a flow path adjacent to the catalyst layer (Patent Document 1, etc.).

[0007] Conventional systems require the installation of a system (heat transfer system) for circulating a heat transfer fluid (heat transfer oil) either inside or outside the methanation system unit. Furthermore, the operating temperature of the heat transfer fluid is typically below 300°C, and in structures where the catalyst layer and heat transfer fluid flow path are adjacent to each other, there is a concern that the heat transfer fluid may deteriorate prematurely due to exposure to high temperatures exceeding 500°C.

[0008] This disclosure aims to provide a methanation reaction apparatus and a methanation reaction method that can control temperature without using a heat transfer fluid system. [Means for solving the problem]

[0009] (1) The methanation reactor relating to this disclosure is A methanation reactor that brings a raw material gas into contact with a catalyst to carry out a methanation reaction, A reaction tube body having an inner tube arranged in the vertical axis direction, an outer tube positioned around the outer circumference of the inner tube, a first internal space between the outer tube and the inner tube, and a second internal space inside the inner tube, A catalyst layer formed in the second internal space, A raw material gas introduction line for introducing raw material gas from the lower end side of the first internal space, A raw material gas discharge line is provided, which discharges the raw material gas from the upper end of the first internal space to the outside of the reaction tube body, and whose line end is connected to the upper end of the inner tube. A methanation reaction apparatus, comprising: a product gas discharge line for discharging the product gas reacted in the catalyst layer from the lower end side of the second internal space. Characterized by the following. (2) A methanation reaction apparatus according to the present disclosure is A methanation reaction apparatus for bringing a raw material gas into contact with a catalyst to cause a methanation reaction, comprising: A reaction tube main body arranged in the vertical axis direction, having an inner tube, an outer tube arranged on the outer periphery of the inner tube, a first internal space between the outer tube and the inner tube, and a second internal space inside the inner tube; A catalyst layer formed in the first internal space; A raw material gas introduction line for introducing the raw material gas from the lower end side of the second internal space; A raw material gas discharge line for discharging the raw material gas from the upper end side of the second internal space to the outside of the reaction tube main body, the line end portion of which is connected to the upper end portion of the outer tube; And a product gas discharge line for discharging the product gas reacted in the catalyst layer from the lower end side of the first internal space. (3) A methanation reaction method according to the present disclosure is A methanation reaction method using a methanation reaction apparatus, comprising: The methanation reaction apparatus comprises: A reaction tube main body arranged in the vertical axis direction, having an inner tube, an outer tube arranged on the outer periphery of the inner tube, a first internal space between the outer tube and the inner tube, and a second internal space inside the inner tube; A catalyst layer formed in the second internal space; A raw material gas introduction line for introducing the raw material gas from the lower end side of the first internal space; A raw material gas discharge line for discharging the raw material gas from the upper end side of the first internal space to the outside of the reaction tube main body, the line end portion of which is connected to the upper end portion of the inner tube; And a product gas discharge line for discharging the product gas reacted in the catalyst layer from the lower end side of the second internal space. The methanation reaction apparatus is characterized by bringing the raw material gas into contact with the catalyst layer to carry out the methanation reaction. (4) The methanation reaction method relating to this disclosure is A methanation reaction method using a methanation reactor, The aforementioned methanation reaction apparatus is A reaction tube body having an inner tube arranged in the vertical axis direction, an outer tube positioned around the outer circumference of the inner tube, a first internal space between the outer tube and the inner tube, and a second internal space inside the inner tube, A catalyst layer formed within the first internal space, A raw material gas introduction line for introducing raw material gas from the lower end side of the second internal space, A raw material gas discharge line is provided, which discharges the raw material gas from the upper end of the second internal space to the outside of the reaction tube body, and whose line end is connected to the upper end of the outer tube. The device comprises a product gas discharge line that discharges the product gas generated by the reaction in the catalyst layer from the lower end of the first internal space, The methanation reaction apparatus is characterized by bringing the raw material gas into contact with the catalyst layer to carry out the methanation reaction. [Effects of the Invention]

[0010] The methanation reaction apparatus and methanation reaction method described herein make it possible to control the temperature, such as the heat of reaction, without using a heat transfer fluid system. [Brief explanation of the drawing]

[0011] [Figure 1A] This is a diagram showing a methanation reactor according to the first embodiment. [Figure 1B] This figure shows another example of a methanation reactor according to the first embodiment. [Figure 2A] This is a diagram showing the methanation reactor during startup. [Figure 2B] This figure shows a methanation reactor during steady-state operation. [Figure 2C]This figure shows the methanation reactor during steady-state operation (temperature control). [Figure 3] This figure shows the axial lengths of the outer tube and the catalyst layer. [Figure 4] This figure shows the reaction tube body according to the first embodiment, along with a temperature graph. [Figure 5] This diagram shows the temperature distribution within the reaction tube. [Figure 6] This diagram shows an embodiment in which a heater is provided on the outer circumference of the reaction tube body. [Figure 7] This figure shows a modified example of the methanation reactor according to the first embodiment. [Figure 8] This figure shows a methanation reactor according to the second embodiment. [Figure 9] This diagram shows the temperature distribution within the reaction tube. [Figure 10] This is a diagram showing a methanation reaction apparatus according to the third embodiment. [Figure 11] This diagram shows the shell-and-tube type reaction tube body. [Figure 12] This is a schematic diagram of a methanation reactor according to a fourth embodiment of the present invention. [Figure 13] This is a schematic diagram of a methanation reactor according to a fourth embodiment of the present invention. [Figure 14] This is a schematic diagram of a methanation reactor according to a fifth embodiment of the present invention. [Figure 15] This is a schematic diagram of a methanation reactor according to a fifth embodiment of the present invention. [Figure 16] This graph shows the test results of the fifth embodiment according to the present invention. [Figure 17] This graph shows the test results related to the conventional technology. [Modes for carrying out the invention]

[0012] <Introduction> Various embodiments of the present invention will be described below with reference to the drawings. However, it should be noted that the technical scope of the present invention is not limited to these embodiments, but extends to the invention described in the claims and its equivalents.

[0013] The methanation reactors 10, 50, and 60 according to each embodiment are devices that utilize the heat generated by the methanation reaction to heat (preheat) the raw material gas within the same reactor. Furthermore, the methanation reactor 10 does not use a heat transfer medium and realizes a system that utilizes the heat generated in the reaction tube to heat the raw material gas. Below, the configuration of the methanation reactor 10 of this embodiment (Figure 1) will be described first, and then the flow of the raw material gas will be described. Note that the "metanation reactor" can also be referred to as, for example, a "metanation reaction system" or a "metanation system".

[0014] <Basic configuration of the methanation reactor 10 according to the first embodiment> Figure 1A shows a methanation reactor according to the first embodiment. Figure 1B shows another example of a methanation reactor according to the first embodiment. As shown in Figure 1A, the methanation reactor 10 includes flow meters 11-13, a reaction tube body 14, a heating section 16, a cooling section 17, a bypass line 18, a first temperature sensor T1, a second temperature sensor T2, a first control valve 21, a heat exchanger 23, and a gas-liquid separator 24. Furthermore, the methanation reactor 10 includes a raw material gas introduction line L1, a raw material gas discharge / inflow line L2, and a product gas discharge line L3.

[0015] More specifically, as shown in Figure 1A, the methanation reactor 10A-1 according to the first embodiment is a methanation reactor that brings a raw material gas G1 into contact with a catalyst (such as a catalyst constituting the catalyst layer 32) to carry out a methanation reaction, The reaction tube body 14 is arranged in the vertical axis direction and has an inner tube 14-1, an outer tube 14-2 positioned around the outer circumference of the inner tube 14-1, a first internal space 15A between the outer tube 14-2 and the inner tube 14-1, and a second internal space 15B inside the inner tube 14-1. A catalyst layer 32 is located within the second internal space 15B, A raw material gas introduction line L1 introduces raw material gas G1 from the lower end (part) of the first internal space 15A, The raw material gas G1 is discharged once from the upper end (part) of the first internal space 15A to the outside of the reaction tube body 14, and the line end L2a is connected to the upper end 14a of the inner tube 14-1, forming a raw material gas discharge / inflow line L2 into which the discharged raw material gas G1 flows. The system includes a product gas discharge line L3 that discharges the product gas G2 generated by the catalytic reaction in the catalyst layer 32 from the lower end side of the second internal space 15B.

[0016] These devices are connected via piping and supply raw material gas G1 to the reaction tube body 14. Raw material gas G1 is a mixture of carbon dioxide (CO2) and hydrogen (H2). As will be described in more detail later, nitrogen (N2) gas may also be supplied to the methanation reactor 10A depending on the circumstances.

[0017] Although not shown in the diagram, typically, protective materials such as insulation and burn prevention components are installed around the outer circumference of the reaction tube body 14, which becomes hot, and around the outer circumference of piping such as the raw material gas discharge / inflow line L2.

[0018] The reaction tube body 14 has a structure similar to a double-tube heat exchanger and is formed from an inner tube 14-1 and an outer tube 14-2 positioned outside of it. In the example shown in Figure 1A, both the inner tube 14-1 and the outer tube 14-2 are cylindrical, and they are installed with their axial directions facing up and down (positioned along the vertical axis), but their shapes are not particularly limited.

[0019] A first internal space 15A is formed in the space between the outer tube 14-2 and the inner tube 14-1, and a second internal space 15B is formed inside the inner tube 14-1. The first internal space 15A is used as a flow passage for the raw material gas G1, and the second internal space 15B is filled with a catalyst to form a catalyst layer 32. As will be described later, the raw material gas G1 that has been discharged to the outside is now contained in the second internal space 15B where the catalyst tank 32 is formed. 1-1 It is used as a passageway.

[0020] Figure 3 shows the axial length of the outer tube 14-2 of the reaction tube body 14 and the catalyst layer 32 inside the inner tube 14-1. As shown in Figure 3, the axial length l1 of the outer tube 14-2 is approximately equal to the axial length l2 of the catalyst layer 32. Furthermore, either one of the lengths may be longer, and in this case, the lengths may be formed such that the relationships l1≧l2 and l1≦l2 are satisfied.

[0021] As shown in Figure 1A, one end (line end) L1a of the raw material gas introduction line L1 is connected to the outside of the lower part of the outer pipe 14-2. The raw material gas introduction line L1 is used to introduce the raw material gas G1 into the outer pipe 14-2.

[0022] Figure 1B shows another example of a methanation reactor according to the first embodiment. In the methanation reactor 10 shown in Figure 1B, a second control valve 22 is installed in the raw material gas introduction line L1, and a bypass passage 18 is connected upstream of this second control valve 22. This bypass passage 18 connects the position of the raw material gas introduction line L1 (L1b) to the position of the raw material gas discharge / inflow line L2 (L2b). The bypass passage 18 is used to directly introduce the raw material gas G1 in the raw material gas introduction line L1 into the raw material gas discharge / inflow line L2 as bypass raw material gas G-1. A third control valve 23 is installed in the middle of the bypass passage 18.

[0023] Here, in the vicinity of the upper portion (upper end portion) of the outer tube 14-2, the piping of the source gas discharge / inflow line L2 is connected. This source gas discharge / inflow line L2 is configured such that the source gas G discharged from the outer tube 14-2 1-1 is once drawn out to the outside, and then the drawn-out source gas G 1-1 is introduced into the inner tube 14-1.

[0024] The source gas discharge / inflow line L2 is provided with a heating unit 16 and a cooling unit 17. The heating unit 16 and the cooling unit 17 are used in the source gas discharge / inflow line L2 to adjust the temperature of the source gas G that has been once drawn out to the outside 1-1 . Here, the heating unit 16, the cooling unit 17, and the like can constitute a temperature adjustment unit (reference numeral omitted). Note that either the heating unit 16 or the cooling unit 17 may be installed first.

[0025] Although details will be described later, depending on the operation status of the apparatus, the source gas G that is in a low temperature state relative to a predetermined set temperature may flow through the source gas discharge / inflow line L2 1-1 , or the source gas G1 that is in a high temperature state may flow therethrough. The heating unit 16 has a function of heating the source gas G drawn out to the outside that flows through the source gas discharge / inflow line L2 1-1 when the temperature of the drawn-out source gas G 1-1 is lower than the set temperature. Further, the cooling unit 17 has a function of cooling the source gas G drawn out to the outside that flows through the source gas discharge / inflow line L2 1-1 when the temperature of the drawn-out source gas G 1-1 is higher than the set temperature.

[0026] One end portion L2a of the source gas discharge / inflow line L2 is connected to the inlet-side end portion (the upper end portion in the example of FIG. 1A) 14a of the inner tube 14-1.

[0027] One end of the generated gas discharge line L3 is connected to the outlet end (lower end in the example in Figure 1A) 14b of the inner pipe 14-1. The generated gas discharge line L3 guides the gas G2 (hereinafter referred to as "generated gas") produced by the catalytic reaction (methanation reaction) that is led out from the inner pipe 14-1.

[0028] A heat exchanger (cooler) 23 is installed in the middle of the generated gas discharge line L3, and a gas-liquid separator 24 is connected to the downstream side of the heat exchanger 23. A valve device 25 is connected to the gas-liquid separator 24, and the separated moisture is automatically drained. The cooling liquid CW piping 26 of the heat exchanger 23 is also supplied to a cooling unit 17 installed in the raw material gas discharge / inflow line L2.

[0029] <Catalyst layer 32> The inside of the inner tube 14-1 is filled with catalyst, forming a catalyst layer 32. Since the reaction tube body 14 has a double-walled structure, the raw material gas G1 (arrow A: upward flow) flows through the outer tube 14-2 introduced by the raw material gas introduction line L1, and the raw material gas (arrow B: downward flow) that has been discharged to the outside is introduced through the raw material gas discharge / inflow line L2. 1-1 This enables heat exchange.

[0030] Furthermore, it is preferable to use a catalyst in the catalyst layer 32 that has high heat resistance and is less likely to deactivate even at temperatures of around 700 to 750°C.

[0031] <Flow of raw material gas G1 and product gas G2> Next, we will explain the flow of the raw material gas G1 and the generated gas G2. As shown in the left portion of Figure 1A, carbon dioxide (CO2) and hydrogen (H2) at room temperature (approximately 40°C or below) are supplied to the raw material gas introduction line L1 via separate pipes. The carbon dioxide and hydrogen merge and mix to form the raw material gas G1. The flow rate of hydrogen is measured by flow meter 11, and the flow rate of carbon dioxide is measured by flow meter 12.

[0032] The raw material gas G1 is introduced into the reaction tube body 14 through the raw material gas introduction line L1 and flows into the inside of the outer tube 14-2. The raw material gas G1 flows through the first internal space 15A inside the outer tube 14-2 and rises as indicated by arrow A, while in contact with the outer surface of the inner tube 14-1. The raw material gas G1 that has reached the top of the first internal space 15A (passage) is discharged from the upper end side of the outer tube 14-2 into the raw material gas discharge / inflow line L2, and the discharged raw material gas G 1-1 It flows into the inner pipe 14-1. Subsequently, the raw material gas G passes through the heating section 16 and cooling section 17 installed in the raw material gas discharge / inflow line L2, and the discharged raw material gas G 1-1 It flows in from the upper end 14a.

[0033] And then, raw material gas G 1-1 However, it is introduced into the second internal space 15B inside the inner tube 14-1 and passes through the catalyst layer 32 as indicated by arrow B (downward flow), causing a methanation reaction to occur due to the catalyst. During this methanation reaction, the temperature of the catalyst layer 32 rises.

[0034] Figure 4 shows the temperature distribution of the reaction tube in the reaction tube body 14 according to the first embodiment. In Figure 4, a graph illustrating the temperature change of the catalyst layer 32 is placed to the right of the reaction tube body 14. In the temperature change graph, the position (height) of the catalyst layer 32 is shown on the horizontal axis, and the temperature (°C) is shown on the vertical axis.

[0035] In the example graph in Figure 4, the temperature of the catalyst layer 32 is approximately 350°C at the upper part 32a of the catalyst on the upper end 14a side of the reaction tube 14. At the upper end, as you move from the inlet portion of the upper end portion 32a of the catalyst towards the lower end, the temperature reaches a maximum (for example, around 730°C) in a range X of about 10-20%. As you move from this maximum temperature point towards the lower end portion 14b on the outlet side, the temperature of the catalyst layer 32 decreases.

[0036] The generated gas G2, which flows out from the lower end 32b of the catalyst layer 32 and is discharged from the inner pipe 14-1, is cooled by passing through the heat exchanger 23 installed in the generated gas discharge line L3. Next, moisture is removed in the gas-liquid separator 24. This moisture-removed gas G3 is supplied to the next process (for example, the second-stage reactor in the embodiment described later).

[0037] The raw material gas G1 is supplied to the reaction tube body 14 continuously, with an upward flow of raw material gas G1 flowing through the temperature-raised catalyst layer 32 and inner tube 14-1, and a downward flow of raw material gas G1 flowing through the outer tube 14-2. 1-1 This refers to the heat exchange that occurs through the pipe wall of the inner pipe 14-1, and the raw material gas G that heads towards the raw material gas discharge / inflow line L2. 1-1 As the catalyst layer 32 is preheated, the generated gas G2 that has passed through the catalyst layer 32 is slightly cooled.

[0038] <Temperature adjustment of raw material gas G1> Next, we will explain the temperature control of the raw material gas G1. As mentioned above, in the example in Figure 1A, for example, raw material gas G1 at about 40°C is supplied to the outer tube 14-2 of the reaction tube body 14 via the raw material gas introduction line L1. The raw material gas G1 that has passed through the first internal space 15A (passage) between the outer tube 14-2 and the inner tube 14-1 is introduced into the inner tube 14-1 via the raw material gas discharge / inflow line L2, but the raw material gas G 1-1 Temperature adjustment is possible using the heating section 16 and the cooling section 17.

[0039] Temperature control in the raw material gas discharge / inflow line L2 is performed by raw material gas G 1-1 The temperature is adjusted to a temperature suitable for introduction into the catalyst layer 32 (a predetermined set temperature). Furthermore, temperature control is performed by a control device (not shown) through the interlocking of a first temperature sensor T1, a second temperature sensor T2, and first to third adjustment valves 21 to 23.

[0040] Here, the "set temperature" is, for example, 200 to 450°C, preferably 300 to 400°C, and more preferably 350°C. However, the optimal "set temperature" is not limited to 350°C, as the activity state of the catalyst 32 is also a factor. Furthermore, the temperature of the raw material gas G1 may be measured by measuring the surface temperature (skin temperature) of the piping through which the raw material gas G1 flows or by measuring the temperature of the actual gas fluid.

[0041] The raw gas discharge / inflow line L2 is equipped with a first temperature sensor T1 and a second temperature sensor T2. The first temperature sensor T1 is positioned to detect the temperature upstream of the heating unit 16, and the second temperature sensor T2 is positioned to detect the temperature downstream of the cooling unit 17. For example, thermocouples can be used as the first temperature sensor T1 and the second temperature sensor T2. In Figure 1A, the first temperature sensor T1, the second temperature sensor T2, and electrical signal lines (control signal lines, etc.) related to the control unit (not shown) are indicated by dashed lines.

[0042] Based on the output of the temperature detected by the first temperature sensor T1 (hereinafter referred to as detected temperature t1) and the temperature detected by the second temperature sensor T2 (hereinafter referred to as detected temperature t2), the temperature of the raw material gas G1 is determined, and the control unit controls the first to third adjustment valves 21 to 3 adjustment valves 23 and the heating unit 16 so that they reach predetermined set temperatures. Note that the first to third adjustment valves 21 to 3 adjustment valves 23 and the heating unit 16 may be operated manually.

[0043] As mentioned above, the second control valve 22 is located in the middle of the raw material gas introduction line L1, and the third control valve 23 is located in the middle of the bypass line 18. The third control valve 23 is located in the piping (coolant piping) 26 that passes through the cooling section 17, in the downstream portion of the cooling section 17.

[0044] Next, the operation of the methanation reactor during startup will be explained with reference to Figure 2A. Figure 2A is a diagram showing the methanation reactor during startup. As shown in Figure 2A, when the methanation reactor 10 is started up, the first control valve 21 and the second control valve 22 are closed (shown in black in the figure), and the third control valve 23 is open. In this state, all of the raw material gas G1 is supplied to the raw material gas discharge / inflow line L2 via the bypass line 18. Furthermore, while the methanation reactor 10 is running, any gas, such as nitrogen gas (N2) or a mixture of nitrogen and hydrogen, may be supplied to the reaction tube body 14.

[0045] During cold startup and when the detected temperature t1 has not reached the aforementioned set temperature, the third adjustment valve 23 is closed, and the supply of coolant to the cooling unit 17 is stopped, while the heating unit 16 supplies the raw material gas G 1-1 The raw material gas G is heated. 1-1 However, it is supplied to the catalyst layer 32 inside the inner tube 14-1.

[0046] Source gas G directed toward catalyst layer 32 1-1 The temperature is also monitored by the second temperature sensor T2. If the temperature t2 detected by the second temperature sensor T2 reaches or exceeds the set temperature, the control unit automatically adjusts the opening of the third adjustment valve 23 and supplies coolant to the cooling unit 17. At this time, it is possible to stop heating by the heating unit 16 and perform cooling by the cooling unit 17, or to continue heating by the heating unit 16 while gradually reducing the output and performing cooling by the cooling unit 17.

[0047] In the methanation reactor 10 during operation, once each part reaches a predetermined temperature, hydrogen and carbon dioxide are supplied in a 4:1 ratio. The methanation reaction begins, and the catalyst layer 32 generates heat, causing the temperature of the inner tube 14-1 to rise. When the temperature of the upper end of the catalyst layer 32 reaches a predetermined temperature (e.g., 350°C), the control unit begins to slowly close the second adjustment valve 22 and then slowly open it to bring the detected temperature t1 and detected temperature t2 to predetermined set temperatures. Automatic coordinated opening and closing adjustments are performed by the control unit in conjunction with the third adjustment valve 23, resulting in a steady-state operation.

[0048] Figure 2B shows the methanation reactor during steady-state operation. As shown in Figure 2B, in a typical example of steady-state operation, the raw material gas G1 is distributed to the raw material gas introduction line L1 and the bypass line 18, and the openings of the first control valve 21 to the third control valve 23 are adjusted arbitrarily in coordination.

[0049] The heating unit 16 has a third temperature sensor (not shown) inside, which is different from the first temperature sensor T1 and the second temperature sensor T2. The heating unit 16 controls the output so that the temperature t3 detected by the third temperature sensor reaches a predetermined set temperature.

[0050] Regardless of the opening and closing adjustments of the first and second adjustment valves, if the temperature t3 detected by the third temperature sensor has not reached the set temperature, the heating unit 16 in automatic operation will heat the raw material gas G1. If the detected temperature t3 has reached or exceeded the set temperature, the heating unit 16 will reduce its output and suppress the heating of the raw material gas G1.

[0051] If, in this state, the detected temperature t2 further exceeds the set temperature, the opening of the third adjustment valve 23 is automatically adjusted, and the supply of coolant to the cooling unit 17 is adjusted to lower t2.

[0052] In this case, it is possible to manually stop heating by the heating unit 16 and perform cooling by the cooling unit 17, or to continue controlling the heating unit 16 while performing cooling by the cooling unit 17, or to make any other setting.

[0053] By adjusting the opening and closing of the second adjustment valve 22 and the third adjustment valve 23 in conjunction with the detected temperature t1 or t2, the raw material gas G1 can be arbitrarily distributed to the raw material gas introduction line L1 and the bypass line 18, and then rejoined in the raw material gas discharge / inflow line L2.

[0054] For example, if the detected temperature t1 is higher than the set temperature, the second adjustment valve 22 is slowly closed, and at the same time, the third adjustment valve 23 is slowly opened, thereby controlling the flow of raw material gas G through the raw material gas discharge / inflow line L2. 1-1 It can lower the temperature.

[0055] Also, if, hypothetically, after bypassing, the raw material gas G at the outlet of the heating section 16 1-1 If the temperature is higher than the set temperature, cooling can be performed by the cooling unit 17. Specifically, raw material gas G 1-1 If the detected temperature t2 rises above the set temperature, the third adjustment valve 23 is slowly opened to supply coolant to the cooling unit 17, thereby supplying the raw material gas G 1-1 It is possible to cool it.

[0056] Furthermore, if the detected temperature t1 and detected temperature t2 are lower than the set temperature, the state of each adjustment valve will be as follows: the first adjustment valve 21 will automatically open slowly, the second adjustment valve 22 will automatically close slowly, and the third adjustment valve 23 will automatically close slowly, and the raw material gas G will be supplied to the heating unit 16. 1-1 This control system heats up to the set temperature.

[0057] When heating is at its maximum, as shown in Figure 2C, the state of each control valve is as follows: the first control valve 21 is fully open, the second control valve 22 is fully closed (shown in black), and the third control valve 23 is fully closed (shown in black). The raw material gas is not distributed to the bypass line 18, but is supplied only to the raw material gas introduction line L1, and then the raw material gas G is heated in the heating section 16. 1-1 This control system heats the food to the set temperature.

[0058] Furthermore, the heating unit 16 can employ any heat source, such as an electric heater, burner, or catalytic combustion.

[0059] <Measured operating temperatures for raw material gas G1 and catalyst layer 32> Figure 5 shows an example of the temperature distribution inside the reaction tube. Figure 5 shows the raw material gas G 1-1 The measured temperature values ​​for the catalyst layer 32 during device operation are shown. In Figure 5, temperature values ​​are shown enclosed in rectangular frames on the left and right sides of the reaction tube body 14. Temperature measurements revealed that the lowest point inside the outer tube 14-2 was approximately 250°C. Furthermore, the temperature in the middle section of the outer tube 14-2 was approximately 650°C, which was the highest temperature inside the outer tube 14-2. The highest point inside the outer tube 14-2 was approximately 480°C.

[0060] These temperatures were measured by installing a sheath tube containing a temperature sensor (in this case, a thermocouple) inside the outer tube 14-2, although this is not shown in the diagram.

[0061] The temperature near the upper end (inlet side end) of the catalyst layer 32 was approximately 350°C. Furthermore, the temperature measured at a position above the middle of the catalyst layer 32 was approximately 730°C, which was the highest temperature. The temperature near the lower end of the catalyst layer 32 was also approximately 350°C.

[0062] These temperatures were measured by placing a sheath tube containing a temperature sensor (in this case, a thermocouple) at the axial position of the catalyst layer 32, although this is not shown in the diagram.

[0063] <Effects of the invention according to the first embodiment> According to the methanation reactor 10 described above, the reaction heat generated in the catalyst layer 32 in the inner tube 14-1 is used to heat (preheat) the raw material gas G1 by exchanging heat with the raw material gas flowing through the first internal space 15A in the adjacent outer tube 14-2. The heated raw material gas G1 is then supplied to the catalyst layer 32 to cause the methanation reaction.

[0064] Furthermore, as mentioned in prior art document 1 above, it becomes possible to induce the methanation reaction with a simple system without using a system (heat transfer system) for supplying and circulating a heat transfer medium to remove heat from the catalyst layer.

[0065] In other words, by using a catalyst with excellent heat resistance, it is possible to create a simple system in which this high-temperature section is used solely for preheating the raw material gas G1, without requiring a dedicated system to forcibly remove heat from the high-temperature catalyst layer.

[0066] Furthermore, the absence of a heat transfer system allows for the creation of a compact methanation reactor 10. Additionally, the elimination of the heat transfer system reduces the installation area of ​​the methanation reactor 10. Moreover, the methanation reaction can be initiated without requiring the use of a significant amount of additional energy for a heat transfer system.

[0067] Furthermore, for the methanation reaction CO2 + 4H2 → CH4 + 2H2O, the raw material gas G supplied to the catalyst layer 32 is required. 1-1 The lower limit temperature is 200-300°C. A raw material gas G with a temperature of 200-300°C or higher is introduced into the catalyst layer 32. 1-1 If the necessary chemicals are supplied, an exothermic reaction will occur, enabling a self-contained methanation reaction.

[0068] However, if the temperature of the catalyst layer 32 rises excessively (for example, above 750°C), there are concerns that the catalyst may deteriorate, the reverse reaction of methanation may occur, or the efficiency may decrease. Therefore, in the methanation reactor 10 of this embodiment, the raw material gas G 1-1 It is necessary to properly control the temperature of the catalyst layer 32. In the methanation reactor 10, a heating section 16 and a cooling section 17 are provided, so the raw material gas G 1-1 It is possible to properly control the temperature.

[0069] Here, temperature control using the heating section 16 and the cooling section 17 refers, for example, to the raw material gas G introduced from the outer pipe 14-2 to the raw material gas discharge / inflow line L2. 1-1 If the temperature is too high compared to the reference temperature, the output of the heating unit 16 is reduced and the cooling unit 17 cools the raw material gas G 1-1 The ability to cool it.

[0070] Furthermore, the axial length l1 of the outer tube 14-2 is equal to or greater than the axial length l2 of the catalyst layer 32, and is formed to satisfy the relationship l1≧l2. 1-1 However, it is possible to preheat thoroughly over a wide area.

[0071] Furthermore, since the axial length l1 of the outer tube 14-2 is formed to be greater than or equal to the axial length l2 of the catalyst layer 32, a temperature decrease can be expected near the lower end (outlet end) of the catalyst layer 32 by heat exchange with the raw material gas G1 introduced into the first internal space 15A. In methanation, which is an exothermic reaction, this point is advantageous in terms of equilibrium. Here, the axial length (vertical axis direction) of the outer tube 14-2 is not limited to being longer than the catalyst layer 32, but may be, for example, about the same length as the catalyst layer 32.

[0072] The first embodiment can also take the following form.

[0073] Figure 6 shows an embodiment in which a heater is provided on the outer circumference of the reaction tube body. As shown in Figure 6, the reaction tube body 14 may have a structure in which a heater 19 is provided on its outer circumference to heat the raw material gas G1 inside the outer tube 14-2. Heating the raw material gas G1 with the heater 19 can shorten the time from startup to steady-state operation.

[0074] Although not shown in the diagram, for example, a heating element (heating element for the catalyst layer) such as a heater may be attached to the outside of the inner tube 14-1 to heat the inner tube 14-1 and the catalyst layer 32. In this way, the raw material gas G will be heated in the catalyst layer 32. 1-1 Before supplying the catalyst, the catalyst layer 32 can be preheated by the catalyst layer heating section, which speeds up the startup process.

[0075] Furthermore, the reaction tube body 14 may have a structure in which a portion of the first internal space 15A inside the outer tube 14-2 is filled with heat transfer particles or the like to promote heat exchange.

[0076] Although not shown in the diagram, a system with multiple heat exchangers 23 may be designed, provided that the generated gas G2 can ultimately be cooled to the temperature required for gas-liquid separation. For example, it can be combined with a heat supply system for other equipment such as a carbon dioxide recovery device.

[0077] In the first embodiment, the gas (raw material gas G1) flowing through the first internal space 15A and the gas (raw material gas G) flowing through the second internal space 15B 1-1 The generated gas (G2) is flowing countercurrently, but it may also be flowing parallel.

[0078] Figure 7 shows a modified example of the methanation reactor according to the first embodiment. As shown in the schematic diagram in Figure 7, the methanation reactor 100 has the roles of the inner tube 14-1 and the outer tube 14-2 reversed, with the catalyst layer 32 formed in the first internal space 15A inside the outer tube 14-2, and the raw material gas G in the second internal space 15B inside the inner tube 14-1. 1-1 The structure may also be such that a passage is formed.

[0079] The methanation reactor 100 has a raw material gas introduction line L1 that introduces raw material gas G1 from the lower end of the second internal space 15B, a raw material gas discharge / inflow line L2 that discharges the raw material gas from the upper end of the second internal space 15B to the outside of the reaction tube body 14 and whose line end is connected to the upper end of the outer tube 14-2, and a product gas discharge line L3 that discharges the product gas G2 that has reacted in the catalyst layer 32 from the lower end of the first internal space 15A. Configurations not shown are the same as those of the methanation reactor 10 in Figure 1A, so their explanation is omitted.

[0080] <Second Embodiment> Figure 8 shows a methanation reactor according to the second embodiment. A methanation reactor 50 according to the second embodiment will be described with reference to Figure 8. The methanation reactor 50 in the example of Figure 8 is configured by connecting two first methanation reactors 10A and second methanation reactors 10B, which have the same configuration as in the first embodiment, in series. For this reason, in the following, the same reference numerals will be used for components of each methanation reactor 10A and 10B as in the first embodiment, and their descriptions will be omitted as appropriate.

[0081] The product gas discharge line L3-A in the upstream methanation reactor 10A is connected to the outer pipes 14-2 and L2-B in the downstream methanation reactor 10B. In the upstream methanation reactor 10A, similar to the methanation reactor 10 according to the first embodiment (Figure 1A), the moisture in the product gas G2-A is condensed and removed, and the gas is introduced into the downstream methanation reactor 10B via the product gas discharge line L3-A.

[0082] The product gas discharge line L3-A in the upstream methanation reactor 10A is spatially connected to the first internal space 15A (passage) between the inner pipe 14-1 and the outer pipe 14-2 in the downstream methanation reactor 10B. Furthermore, the product gas discharge line L3-A in the upstream methanation reactor 10A also functions as the raw material gas introduction line L1-B in the downstream methanation reactor 10B. In addition, the product gas G2-A in the upstream methanation reactor 10A becomes the raw material gas G1-B in the downstream methanation reactor 10B.

[0083] In the downstream methanation reactor 10B, the heat exchanger 23 is supplied with a coolant (e.g., cooling water) that has passed through the heat exchanger 23 of the upstream methanation reactor 10A. However, the system is not limited to this, and the upstream methanation reactor 10A and the downstream methanation reactor 10B may supply the heat exchanger 23 with a coolant (e.g., cooling water) via independent routes.

[0084] In a methanation reactor 50 with this configuration, the first stage of the methanation reaction is carried out in the upstream methanation reactor 10A, and the second stage of the methanation reaction is carried out in the downstream methanation reactor 10B. The first stage of the methanation reaction has a CO2 conversion rate of approximately 80-90%, and the second stage of the methanation reaction ensures a CO2 conversion rate of 99% or more. As a result, this methanation reactor can produce gas with a methane concentration of 90% or higher, preferably 95% or higher, and more preferably 97-98%. Furthermore, in the case of a two-stage system consisting of a front-stage methanation reactor 10A and a rear-stage methanation reactor 10B, it is preferable to use a nickel (Ni) catalyst for catalyst 32A in the first-stage methanation reactor 10A and a noble metal catalyst (e.g., Ru, Pt, etc.) for catalyst 32B in the second-stage methanation reactor 10B.

[0085] <Measured operating temperatures for raw material gas G1 and catalyst layer 32> Figure 9 shows the temperature distribution within the reaction tube. Figure 9 shows the measured temperatures during operation of the raw material gases G1-A and G1-B (G2-A) and the catalyst layer 32 in the upstream methanation reactor 10A and the downstream methanation reactor 10B. In Figure 9, the numerical values ​​indicating the temperature are enclosed in rectangular frames on the left and right sides of the reaction tube body 14.

[0086] In the example shown in Figure 9, the values ​​for the upstream methanation reactor 10A are the same as those for the methanation reactor 10 according to the first embodiment. In the downstream methanation reactor 10B, the temperature of the outer tube 14-2 near the connection point with the raw material gas introduction line L1-A was approximately 120°C. Furthermore, the temperature of the middle portion of the outer tube 14-2 in the longitudinal direction (up and down direction in the figure) was approximately 450°C, and this temperature was the highest temperature measured in the outer tube 14-2. In addition, the temperature of the outer tube 14-2 near the connection point with the raw material gas discharge / inflow line L2-B was approximately 400°C.

[0087] These temperatures were measured by installing a sheath tube containing a temperature sensor (in this case, a thermocouple) inside the outer tube 14-2, similar to the first embodiment.

[0088] The temperature measured near the upper end (inlet end) of the catalyst layer 32 was approximately 300°C. Furthermore, the temperature measured at a position above the middle of the catalyst layer 32 (the highest temperature measured) was approximately 550°C, and this was the highest temperature measured in the catalyst layer 32. The temperature at the lower end of the catalyst layer 32 was approximately 300°C.

[0089] These temperatures were measured by installing a sheath tube containing a temperature sensor (in this case, a thermocouple) at the axial position of the catalyst layer 32, similar to the first embodiment.

[0090] <Effects of the invention according to the second embodiment> According to the methanation reactor 50 of the second embodiment described above, the same effects of the invention as those of the first embodiment can be achieved with respect to the same parts as those of the first embodiment. Furthermore, according to the methanation reactor 50 of the second embodiment, a CO2 conversion rate close to 100% can be achieved by a methanation reaction in multiple stages (two stages in the example of Figure 9).

[0091] <Third Embodiment> Figure 10 shows a methanation reactor according to the third embodiment. Next, a methanation reactor 60 according to the third embodiment will be described based on Figure 10. The methanation reactor 60 in the example of Figure 10 is configured by connecting methanation reactors 10-1 and 10-2, which have the same configuration as in the first embodiment, in parallel. For this reason, in the following, the same reference numerals will be used for the same configuration as in the first embodiment for each methanation reactor 10-1 and 10-2, and explanations will be omitted as appropriate. This will be described as the first-stage reactor apparatus, but the second-stage reactor apparatus will be configured with a similar structure. Furthermore, multiple methanation reactors can be connected in parallel, and the number can be increased as needed depending on the capacity of the reactor.

[0092] In the methanation reactor 60 according to the third embodiment of the third embodiment, the raw material gas introduction line L1 is branched into multiple lines (two lines in the example in Figure 10). The raw material gas G1 is supplied to each of the methanation reactors 10-1 and 10-2, and the same methanation reaction as in the first embodiment is carried out in each of the methanation reactors 10-1 and 10-2. The product gas G2 obtained from each of the methanation reactors 10-1 and 10-2 passes through the product gas discharge lines L3-1 and L3-2 and merges in the product gas discharge line L3. Water is removed from the product gas G2 in the gas-liquid separator 24 and supplied to the next process (second stage reactor: not shown). Furthermore, it is preferable that the catalyst 32A in the first-stage parallel reactor and the catalyst 32B in the second-stage reactor be nickel (Ni) catalysts for the first-stage methanation reactor 10A and noble metal catalysts (e.g., Ru, Pt, etc.) for the catalyst 32B in the second-stage methanation reactor 10B (not shown).

[0093] <Effects of the invention according to the third embodiment> According to the methanation reactor 60 of the third embodiment described above, the same effects of the invention as the methanation reactor 50 of the first embodiment can be achieved with respect to the same parts as in the first embodiment. Furthermore, according to the methanation reactor 60 of the third embodiment, by performing the methanation reaction in parallel, it is possible to achieve simple scaling up.

[0094] <Modified representation of reaction tube body 14> The structure of the reaction tube body 14 is not limited to a double-tube structure (double-tube type with a single tube) as in the first to third embodiments. For example, in the case of large-scale equipment, it may be a shell-and-tube type structure in which a large number of thin tubes are arranged inside a cylindrical body (shell), as schematically shown in Figure 11. The shell-and-tube type reaction tube body 70 will be described below, but the equipment surrounding the reaction tube body 70 can be the same as the equipment in the example in Figure 1A unless there is a particular problem. The explanation of equipment similar to the example in Figure 1A will be omitted as appropriate.

[0095] Figure 11 shows a shell-and-tube type reaction tube body. The reaction tube body 70 shown in the example in Figure 11 consists of a shell 76, a number of tubes 74, and bonnets 78 and 80 located above and below the shell 76. The tubes 74 are arranged inside the shell 76 with their axial directions facing up and down (vertically aligned).

[0096] In the example shown in Figure 11, only three tubes 74 are shown to avoid a cluttered illustration, but the number of tubes 74 can be increased as appropriate depending on the capacity of the device.

[0097] In Figure 11, arrow C indicates the flow of raw material gas G1 introduced from raw material gas introduction line L1 (not shown). Raw material gas G1 is introduced into the reaction tube body 70 from raw material gas introduction line L1 (not shown). The raw material gas G1 flows inside the shell 76, using the space outside the tube 74 (first internal space) as a passage, and rises while in contact with the outer surface of the tube 74. The raw material gas G1 that reaches the top of the shell 76 flows from the reaction tube body 70 into the raw material gas discharge / inflow line L2 (not shown), returns to the reaction tube body 70, and flows into the space inside the multiple tubes 74 (second internal space), as indicated by arrow D.

[0098] A catalyst layer 82 is formed in the space inside each tube 74. The catalyst layer 82 can be formed using the same catalyst as the catalyst layer 32 in Figure 1A. The raw material gas G1 inside each tube 74 flows out from the lower end of the catalyst layer 82 and is discharged as product gas G2 from the bottom of the reaction tube body 70 to the product gas discharge line L3 (not shown).

[0099] In the example shown in Figure 11, the catalyst layer 82 is formed in the internal space (second internal space) of each tube 74, but this is not the only option. The roles of the tubes 74 and the shell 76 may be reversed, with the catalyst layer 82 formed in the first internal space inside the shell 76, and the second internal space inside the tubes 74 forming a passage for the raw material gas G1.

[0100] <Inventions that can be extracted from the embodiments> From the embodiments described so far, it is possible to extract the following inventions. (1) A methanation reactor (methanation reactors 10, 50, 60, 100, etc.) that brings a raw material gas (raw material gas G1, G1-A, G1-B, etc.) into contact with a catalyst (such as a catalyst constituting the catalyst layer 32) to carry out a methanation reaction, A reaction tube body (reaction tube body 14, etc.) is arranged in the vertical axis direction and has an inner tube (inner tube 14-1, etc.), an outer tube (outer tube 14-2, etc.) arranged around the outer circumference of the inner tube, a first internal space (internal space 15A, etc.) between the outer tube and the inner tube, and a second internal space (internal space 15B, etc.) inside the inner tube. A catalyst layer (such as catalyst layer 32) is formed within the second internal space described above, A raw material gas introduction line (such as raw material gas introduction line L1) introduces the raw material gas from the lower end of the first internal space, A raw material gas discharge line (raw material gas discharge / inflow line L2, etc.) is formed by discharging the raw material gas from the upper end of the first internal space to the outside of the reaction tube body, and the line end (line end L2a, etc.) is connected to the upper end (upper end 14a, etc.) of the inner tube, A methanation reactor characterized by comprising: a generated gas discharge line (e.g., generated gas discharge line L3) for discharging a generated gas (e.g., generated gas G2) reacted in the catalyst layer from the lower end of the second internal space. (2) A methanation reactor (methanation reactors 10, 50, 60, 100, etc.) that brings a raw material gas (raw material gas G1, G1-A, G1-B, etc.) into contact with a catalyst (such as a catalyst constituting the catalyst layer 32) to carry out a methanation reaction, A reaction tube body (reaction tube body 14, etc.) is arranged in the vertical axis direction and has an inner tube (inner tube 14-1, etc.), an outer tube (outer tube 14-2, etc.) arranged around the outer circumference of the inner tube, a first internal space (internal space 15A, etc.) between the outer tube and the inner tube, and a second internal space (internal space 15B, etc.) inside the inner tube. A catalyst layer (such as catalyst layer 32) is formed within the first internal space, A raw material gas introduction line (such as raw material gas introduction line L1) introduces the raw material gas from the lower end of the second internal space, A raw material gas discharge line (raw material gas discharge / inflow line L2, etc.) is formed by discharging the raw material gas from the upper end of the second internal space to the outside of the reaction tube body, and the line end (line end L2a, etc.) is connected to the upper end (upper end 14a, etc.) of the outer tube, A methanation reactor characterized by comprising: a generated gas discharge line (e.g., generated gas discharge line L3) for discharging a generated gas (e.g., generated gas G2) reacted in the catalyst layer from the lower end of the first internal space. (3) The methanation reactor according to (1) or (2) above, characterized in that the raw material gas discharge line is provided with a heating section (such as heating section 16) or a cooling section (such as cooling section 17). (4) The methanation reactor according to (1) or (2) above, characterized in that the axial length l1 of the outer tube is equal to or greater than the axial length l2 of the catalyst layer. (5) The methanation reactor according to (1) or (2) above, characterized in that a second control valve (such as a second control valve 22) is installed in the raw material gas introduction line. (6) The system has a bypass route (such as bypass route 18) that bypasses the raw material gas from the raw material gas introduction line to the raw material gas discharge line, The methanation reactor according to (1) or (2) above, characterized in that a third control valve (such as the third control valve 23) is installed in the bypass path. (7) The methanation reactors (methanation reactors 10A, 10B, etc.) are configured in series of two or more, The methanation reactor (methanation reactor 50, etc.) described in (1) or (2) above, characterized in that the generated gas discharge line (generated gas discharge line L3-A, etc.) of the upstream methanation reactor (methanation reactor 10A, etc.) is an introduction line that introduces the generated gas (generated gas G2-A, etc.) into the passage between the inner tube and the outer tube of the downstream methanation reactor (methanation reactor 10B, etc.). (8) The methanation reactor according to (7) above, characterized in that the methanation reactor is configured in parallel. (9) The methanation reactor according to (1) or (2) above, characterized in that the reaction tube body is of the shell and tube type (e.g., reaction tube body 70). (10) A methanation reaction method using a methanation reactor (methanation reactors 10, 50, 60, 100, etc.), The aforementioned methanation reaction apparatus is A reaction tube body (reaction tube body 14, etc.) is arranged in the vertical axis direction and has an inner tube (inner tube 14-1, etc.), an outer tube (outer tube 14-2, etc.) arranged around the outer circumference of the inner tube, a first internal space (internal space 15A, etc.) between the outer tube and the inner tube, and a second internal space (internal space 15B, etc.) inside the inner tube. A catalyst layer (such as catalyst layer 32) is formed within the second internal space described above, A raw material gas introduction line (raw material gas introduction line L1, etc.) introduces raw material gases (raw material gases G1, G1-A, G1-B, etc.) from the lower end of the first internal space, A raw material gas discharge line (raw material gas discharge / inflow line L2, etc.) is formed by discharging the raw material gas from the upper end of the first internal space to the outside of the reaction tube body, and the line end (line end L2a, etc.) is connected to the upper end (upper end 14a, etc.) of the inner tube, The device comprises a generated gas discharge line (e.g., generated gas discharge line L3) that discharges the generated gas (e.g., generated gas G2) that has reacted in the catalyst layer from the lower end of the second internal space, A methanation reaction method characterized by bringing the raw material gas into contact with the catalyst layer using the methanation reaction apparatus to carry out a methanation reaction. (11) A methanation reaction method using a methanation reactor (methanation reactors 10, 50, 60, 100, etc.), The aforementioned methanation reaction apparatus is A reaction tube body (reaction tube body 14, etc.) is arranged in the vertical axis direction and has an inner tube (inner tube 14-1, etc.), an outer tube (outer tube 14-2, etc.) arranged around the outer circumference of the inner tube, a first internal space (internal space 15B, etc.) between the outer tube and the inner tube, and a second internal space (internal space 15B, etc.) inside the inner tube. A catalyst layer (such as catalyst layer 32) is formed within the first internal space, A raw material gas introduction line (raw material gas introduction line L1, etc.) introduces raw material gases (raw material gases G1, G1-A, G1-B, etc.) from the lower end of the second internal space, A raw material gas discharge / inflow line (raw material gas discharge / inflow line L2, etc.) is formed by discharging the raw material gas from the upper end of the second internal space to the outside of the reaction tube body, and the line end (line end L2a, etc.) being connected to the upper end (upper end 14a, etc.) of the outer tube, The device comprises a generated gas discharge line (e.g., generated gas discharge line L3) that discharges the generated gas (e.g., generated gas G2) that has reacted in the catalyst layer from the lower end of the first internal space, A methanation reaction method characterized by bringing the raw material gas into contact with the catalyst layer using the methanation reaction apparatus to carry out a methanation reaction. (12) The methanation reactor, The line has a bypass route (such as bypass route 18) that bypasses the raw material gas from the raw material gas introduction line to the raw material gas discharge line. A second regulating valve (such as the second regulating valve 22) is installed in the aforementioned raw material gas introduction line. A third adjustment valve (such as the third adjustment valve 23) is installed in the aforementioned bypass path. The methanation reaction method according to (10) or (11) above, characterized in that when the methanation reaction apparatus is started, the third control valve is opened and the second control valve is closed. (13) The methanation reaction method according to (12) above, characterized in that the opening degree of the second control valve and the opening degree of the third control valve are controlled according to the temperature of the raw material gas in the raw material gas discharge line. (14) The methanation reaction apparatus is It is equipped with a heating section (such as heating section 16) or a cooling section (such as cooling section 17), The methanation reaction method according to (13) above, characterized in that the temperature of the raw material gas is controlled by the heating unit or the cooling unit.

[0101] <Fourth Embodiment> Figures 12(A) to (C) are schematic diagrams of a methanation reactor according to the fourth embodiment of the present invention. As shown in Figure 12(A), the methanation reactor according to this embodiment is packed with a mixed catalyst 22 in a predetermined ratio within a reactor 111 into which a raw material gas G1 containing carbon dioxide (CO2) and hydrogen (H2) is introduced. This mixed catalyst 22 is obtained by mixing a methanation catalyst 120, which converts carbon dioxide into methane, and a reverse shift catalyst 121, which reacts by endothermically releasing some of the heat generated by the methanation reaction. Here, the mixing ratio (volume %) of the reverse shift catalyst 121 and the methanation catalyst 120 is preferably, for example, 90:10 to 40:60.

[0102] The reactor 111 is equipped with a gas introduction pipe 12A for introducing the raw material gas G1 and a gas discharge pipe 12B for discharging the product gas (exhaust gas) G2 at its upper and lower ends.

[0103] The raw material gas G1 is preferably a mixture of carbon dioxide (CO2) and hydrogen (H2) in a 1:4 ratio. The reaction start temperature of the reactor 111 is 200 to 400°C, preferably 270 to 300°C. The carbon dioxide (CO2) and hydrogen (H2) introduced from the gas introduction pipe 112A are converted into methane (CH4) and water (H2O) by the methanation catalyst 120, as shown in formula (1) below.

[0104] (chemical 1) CO2 + 4H2 → CH4 + 2H2O ... (1)

[0105] In this process, the reverse-shift catalyst 121 adjacent to the methanation catalyst 120 converts the introduced carbon dioxide (CO2) and hydrogen (H2) into carbon monoxide (CO) and water (H2O), as shown in equation (2) below.

[0106] (Case 2) CO2 + H2 → CO + H2O ... (2)

[0107] In other words, the introduced carbon dioxide generates heat (+165.0 kJ / mol) on the methanation catalyst 120 through the methanation reaction shown in equation (1) above. On the adjacent reverse-shift catalyst 21, a portion of the heat generated in the methanation catalyst 20 is absorbed (-41.2 kJ / mol), and the reverse-shift reaction proceeds as shown in equation (2) above.

[0108] Thus, if the heat generated by the methanation reaction in equation (1) is thermally offset or nearly offset by the heat absorbed by the reverse shift reaction in equation (2), the rapid temperature rise of the catalyst layer near the inlet of reactor 111, for example to 600°C or higher, will be mitigated.

[0109] Based on the above, according to this embodiment, a portion of the heat generated by the methanation reaction of formula (1) is utilized in the endothermic reaction by the reverse shift reaction of formula (2), thereby exhibiting a kind of heat cancellation effect and mitigating the rapid temperature rise of the catalyst layer.

[0110] Furthermore, by mixing the methanation catalyst 20 and the reverse shift catalyst 21 produced by the endothermic reaction within the reactor 111 of a single reaction field, a portion of the heat generated by the methanation reaction can be utilized in the endothermic reaction produced by the reverse shift reaction, thereby exhibiting a kind of heat cancellation effect.

[0111] Figure 13 shows an example of a schematic diagram of a methanation reactor, but the present invention is not limited thereto. As shown in Figure 13, the methanation reactor 10A of this embodiment consists of a gas introduction pipe 112A for introducing a raw material gas G1 consisting of carbon dioxide (CO2), hydrogen (H2), and purge nitrogen (N2), a reactor 111 filled with a methanation catalyst 120 and a reverse shift catalyst 121 in a predetermined ratio, a preheater 131 for preheating the raw material gas G1 before introducing it into the reactor 111, a heater 132 for heating the inside of the reactor 111, and a gas meter 133. Pressure gauges P are also installed in various places (not all are shown). A reaction tube thermometer (not shown) for measuring the internal temperature is provided inside the reactor 111.

[0112] Here, in the present invention, a methanation catalyst refers to a catalyst that converts carbon dioxide (CO2) and hydrogen (H2) into methane (CH4) and water (H2O) through a catalytic reaction, as shown in formula (1) above, to produce a generated gas. Examples of methanation catalysts include those in which at least one catalytically active component such as Pt, Ru, Ni, and Pd is supported on a carrier such as alumina, but the present invention is not limited thereto.

[0113] Furthermore, in this invention, a reverse shift catalyst refers to a catalyst that converts carbon dioxide (CO2) and hydrogen (H2) into carbon monoxide (CO) and water (H2O) through a catalytic reaction. Examples of reverse shift catalysts include those in which at least one catalytically active component, such as Mn or Pd, is supported on a carrier such as alumina, or those made of oxides of Fe or Cr, but this invention is not limited to these.

[0114] Furthermore, as shown in Figure 12(B), when mixing the methanation catalyst 120 and the reverse shift catalyst 121, an endothermic region consisting only of the reverse shift catalyst 121 may be provided in a region perpendicular to the gas flow direction, spaced at a predetermined interval from the inlet side, to further suppress heat generation. The height ratio (thickness) of the packing layer consisting only of the reverse shift catalyst 121 may be appropriately changed depending on the degree of heat cancellation. In this way, it can be expected that the heat cancellation effect will be further improved by using a packing layer consisting only of the reverse shift catalyst 121.

[0115] Alternatively, as shown in Figure 12(C), a mixed catalyst may be packed into the common carrier 123, in which the catalytically active component 120a of the methanation catalyst 120 and the catalytically active component 121a of the reverse-shift catalyst 121 are supported on the common carrier 123 in a predetermined ratio. In this way, by supporting the catalytic active components 20a and 21a of the methanation catalyst and the reverse shift catalyst on the common carrier 23, the catalyst packing efficiency is improved. The mixing ratio of the catalytic active component 21a of the reverse shift catalyst 21 and the catalytic active component 20a of the methanation catalyst 20 supported on the common carrier 23 is preferably a mixing ratio calculated from 90:10 to 40:60, the same as when each catalyst is mixed individually.

[0116] As described above, according to the present invention, in temperature control in the methanation reactor, by providing a reactor 111 in which the methanation catalyst 120 and the reverse shift catalyst 121 are packed in a predetermined ratio, the rapid exothermic reaction of the raw material gas G1 can be mitigated.

[0117] This allows for the reduction or simplification of the cooling function in the methanation device, resulting in a simpler device configuration and cost reduction.

[0118] <Fifth Embodiment> Figure 14 (Figures 14(A) to (D)) is a schematic diagram of a methanation reactor according to the fifth embodiment of the present invention.

[0119] As shown in Figure 14(A), the methanation reactor of the fifth embodiment is configured such that the reactor 111 is divided into a first reaction region 111A and a second reaction region 111B from the gas inlet side to the gas outlet side, the first reaction region 111A is filled with a mixed catalyst 122 obtained by mixing the methanation catalyst 20 and the reverse shift catalyst 21 in a predetermined ratio, and the second reaction region 111B is filled with only the methanation catalyst 120.

[0120] According to this embodiment, carbon dioxide introduced into the first reaction region 111A of the reactor 111 is exothermic (+165.0 kJ / mol) on the methanation catalyst 120 by the methanation reaction of formula (1) above. On the adjacent reverse shift catalyst 21, a portion of the heat generated in the methanation catalyst 20 is absorbed (-41.2 kJ / mol), and the reverse shift reaction from carbon dioxide to carbon monoxide of formula (2) above proceeds.

[0121] Thus, if the heat generated by the methanation reaction in equation (1) is thermally offset or nearly offset by the heat absorbed by the reverse shift reaction in equation (2), the rapid temperature rise of the catalyst layer near the inlet of reactor 111, for example to 600°C or higher, will be mitigated.

[0122] If the methanation reaction does not proceed sufficiently in the first reaction region 111A, the unreacted carbon dioxide in the gas outlet of the first reaction region is converted into methane (CH4) and water (H2O) by the methanation catalyst 120 by the second reaction region 111B, as shown in formula (1) above. Furthermore, the carbon monoxide (CO) produced by the reverse shift reaction is converted to methane (CH4) and water (H2O) by the methanation catalyst 20 in the second reaction region 111B, as shown in equation (3) below. Thus, almost all of the carbon dioxide in the introduced raw material gas G1 is converted to methane.

[0123] (3) CO+3H2→CH4+H2O…(3)+206.2kJ / mol

[0124] When these reaction equations (2) and (3) are combined, the carbon monoxide (CO) produced cancels out, and the total reaction ends up being the same as equation (1).

[0125] Thus, comparing reaction equation (1) with the sum of reaction equations (2) and (3), although the total amount of heat generated in the reaction remains the same, if the reactions of equations (1) and (2) in the first reaction region 111A are thermally canceled out or nearly so, the rapid temperature rise of the catalyst layer near the inlet of reactor 111, for example to 600°C or higher, will be mitigated.

[0126] Based on the above, according to this embodiment, a portion of the heat generated by the methanation reaction of formula (1) is utilized in the endothermic reaction by the reverse shift reaction of formula (2), thereby exhibiting a kind of heat cancellation effect and mitigating a rapid rise in the catalyst layer temperature.

[0127] Here, the volume ratio of the first reaction region 111A to the second reaction region 111B is preferably 95:5 to 30:70, more preferably 80:20 to 30:70.

[0128] Furthermore, the methanation reactor shown in Figure 14(B) has a second reaction region 111B downstream of the first reaction region 111A in Figure 11(B), similar to Figure 14(A). As a result, the methanation reaction (1) and the reverse shift reaction (2) described above occur in the first reaction region, and in the second reaction region, the carbon monoxide (CO) and unreacted carbon dioxide (CO2) generated by the reverse shift reaction are converted into methane (CH4) and water (H2O) by the methanation catalyst 20 in the second reaction region 111B, as described in equations (1) and (3), and almost all of the carbon dioxide in the raw material gas G1 is converted into methane.

[0129] Furthermore, the methanation reactor shown in Figure 14(C) has a second reaction region 111B downstream of the first reaction region 111A in Figure 12(C), similar to Figure 14(A). As a result, the methanation reaction (1) and the reverse shift reaction (2) described above occur in the first reaction region, and in the second reaction region, the carbon monoxide (CO) and unreacted carbon dioxide (CO2) generated by the reverse shift reaction are converted into methane (CH4) and water (H2O) by the methanation catalyst 20 in the second reaction region 111B, as shown in equations (1) and (3), and almost all of the carbon dioxide in the raw material gas G1 is converted into methane.

[0130] An example of the methanation reactor of this embodiment is shown in Figure 15. As shown in Figure 15, the configuration of the methanation reactor 10B of this embodiment is the same as the configuration of the methanation reactor 10A shown in Figure 13, so a detailed explanation is omitted. The methanation reactor 10B of this embodiment has a first reaction region 111A and a second reaction region 111B in the reactor 111. The reactor 111 is the one shown in Figures 14(A) to 14(C) above.

[0131] The methanation reaction method comprises a first reaction step in which the reactor 111 is divided into a first reaction region 111A and a second reaction region 111B from the gas inlet side to the gas outlet side of the raw material gas G1, a mixed catalyst 22 obtained by mixing a methanation catalyst 20 and a reverse shift catalyst 21 in a predetermined ratio is packed into the first reaction region 111A, and the introduced carbon dioxide is converted into methane by the methanation catalyst 20, and the introduced carbon dioxide is converted into carbon monoxide by a reverse shift reaction which absorbs some of the heat generated by the methanation reaction, and a second reaction step in which only the methanation catalyst 20 is packed into the second reaction region, and the unreacted carbon dioxide is converted into methane, and the carbon monoxide produced by the reverse shift reaction is converted into methane.

[0132] In this methanation reaction method, in the first reaction region 111A, the methanation catalyst 20 converts carbon dioxide in the raw material gas G1 into methane, and the reverse shift catalyst 21 converts carbon dioxide into carbon monoxide. In the second reaction region 111B, the methanation catalyst 20 converts carbon monoxide and unreacted carbon dioxide into methane (CH4), so that almost all of the carbon dioxide in the raw material gas G1 can be converted into methane. As described above, according to the present invention, when a methanation reaction occurs between carbon dioxide and hydrogen introduced into a reactor 111 using a methanation catalyst 120, a rapid rise in the catalyst layer temperature can be mitigated by a simple method.

[0133] (Example test) The following describes test examples demonstrating the effects of the present invention. In this test example, as shown in Figure 14(D), the reactor 111 with a diameter of 20 mm was divided into two parts: a first reaction region 111A and a second reaction region 111B. 15 ml of mixed catalyst was packed into the first reaction region 111A, and 15 ml of methanation catalyst was packed into the second reaction region 111B. The mixing ratio of the mixed catalyst layers was 70% by volume of reverse-shift catalyst and 30% by volume of methanation catalyst (note that the illustration of the mixing ratio is simplified in the figure).

[0134] In contrast, a control was used in which the reaction vessel was not divided into a first reaction region 111A and a second reaction region 111B, but was filled only with a 30 ml catalyst layer of methanation catalyst 20. In both cases, the catalyst used was reduced at a predetermined temperature.

[0135] The preheating temperature in the preheater 131 was set to 200°C, the reaction temperature in the reactor 111 was set to 300°C, and the reaction pressures were set to 0.1 MPaG and 0 MPaG. A carbon dioxide methanation test was conducted by supplying 2 NL / min of hydrogen, followed by 0.5 NL / min of carbon dioxide. The catalyst layer temperature distribution at this time is shown in Figures 16 and 17 (Figure 16 shows the catalyst layer temperature distribution in Figure 14(D), and Figure 17 shows the temperature distribution of the methanation catalyst 120 only). Furthermore, plot A in the figure represents a reaction pressure of 0.1 MPaG, and plot B represents a reaction pressure of 0 MPaG. Plot C in the figure represents a state without the introduction of carbon dioxide. In Figures 16 and 17, the catalyst height on the horizontal axis is the distance from the gas inlet of the test apparatus in the direction of gas flow (downward in this example). It is preferable that the reaction pressure in reactor 111 be in the range of 0 MPaG (atmospheric pressure) to less than 1 MPaG.

[0136] The methanation catalyst used in the test was "Aeronite® agAl-NiPd" (product name), manufactured by Itochu Ceratec Co., Ltd. Furthermore, the reverse shift catalyst is "Aeronite (registered trademark) agAl-MnPd" (product name) manufactured by Itochu Ceratec Co., Ltd.

[0137] Comparing Figure 16 and Figure 17, it can be seen that when the reaction vessel 111 is not divided into a first reaction region 11A and a second reaction region 111B, a rapid temperature increase is observed near the entrance. In contrast, when the reaction vessel 111 was divided into a first reaction region 111A and a second reaction region 111B, the rapid temperature rise near the entrance was mitigated. Furthermore, in plot A of Figure 16, the temperature rise near the inlet was less than 500°C (485°C) in the present invention, but it exceeded 500°C (515°C) in the conventional plot A shown in Figure 17.

[0138] As described above, according to the present invention, by mixing a methanation catalyst and a reverse shift catalyst in a single reaction field, a portion of the heat generated by the methanation reaction can be utilized in the endothermic reaction caused by the reverse shift reaction, thereby exhibiting a kind of thermal cancellation effect.

[0139] Therefore, since the rapid temperature rise in this reaction can be mitigated without complex processes or complex reactor structures, the cost of the methanation apparatus can be reduced. Furthermore, because it does not easily reach high temperatures, the catalyst lifespan can be extended and the reactor cost can be reduced (by selecting general stainless steel instead of special materials such as heat-resistant steel).

[0140] Furthermore, by eliminating or simplifying conventional cooling functions, and by eliminating the need to fill the reactor with materials that do not contribute to the catalytic reaction, such as alumina balls, it is possible to mitigate the rapid rise in catalyst layer temperature in the methanation reactor, even with a simple configuration.

[0141] The catalyst filled with a mixed catalyst 122, which is a mixture of the methanation catalyst 120 that converts carbon dioxide to methane as described in Embodiment 4 and the reverse shift catalyst 121 for the reverse shift reaction that reacts by endothermically absorbing a portion of the heat generated in the methanation reaction, is preferably applied to the catalyst 32A of the first methanation reactor 10A on the upstream side of the methanation reactor 50 of the second embodiment shown in Figure 8. In this case, it is preferable that the catalyst 32B in the downstream methanation reactor 10B be a noble metal catalyst (for example, Ru, Pt, etc.).

[0142] Similarly, it is preferable to divide the reactor 111 of the fifth embodiment into a first reaction region 111A and a second reaction region 111B from the gas inlet side to the gas outlet side, fill the first reaction region 111A with a mixed catalyst 122 obtained by mixing the methanation catalyst 20 and the reverse shift catalyst 21 in a predetermined ratio, and fill the second reaction region 111B with only the methanation catalyst 120, and apply this to the catalyst 32 of the first methanation reactor 10A on the upstream side of the methanation reactor 50 of the second embodiment as shown in Figure 8 above. In this case, it is preferable that the catalyst 32B in the downstream methanation reactor 10B be a noble metal catalyst (for example, Ru, Pt, etc.).

[0143] <Other> Although this embodiment and its variations have been described in detail above, the present invention is not limited to any particular embodiment. Furthermore, various changes, substitutions, and modifications can be made to the present invention without departing from its scope. [Explanation of Symbols]

[0144] 10, 50, 60 methanation reactors 10A Pre-stage methanation reactor 10B Subsequent methanation reactor 11~13 Flow meter 14, 70: Reaction tube body 14a Upper end 14b Lower end 14-1 Inner pipe 14-2 Outer tube 15A First internal space 15B Second Interior Space 16 Heating section 17 Cooling section 18 Bypass Road 20-22 First adjustment valve to third adjustment valve 23 Heat exchanger 24 Gas-liquid separator 25 Valve device 32 Catalyst layer G1, G1-A, G1-B raw material gas G2, G2-A generated gases L1, L1-A, L1-B raw material gas introduction lines L1a Line end L2, L2-B Raw material gas discharge / inflow lines L2a Line End L3, L3-A generated gas discharge line T1 First temperature sensor T2 Second temperature sensor 10A, 10B Methanation Reactor 111 Reactor 111A First reaction region 111B Second reaction region 112A Gas Inlet Piping 112B Gas discharge piping 120 Methanation Catalysts 120a Methanation catalyst active ingredient 121 Reverse shift catalytic converter 121a Reverse shift catalytic active ingredient 122 Mixed catalyst 123 Common Carrier G1 raw material gas G2 generated gas (exhaust gas)

Claims

1. A methanation reactor that brings a raw material gas into contact with a catalyst to carry out a methanation reaction, A reaction tube body having an inner tube arranged in the vertical axis direction, an outer tube positioned around the outer circumference of the inner tube, a first internal space between the outer tube and the inner tube, and a second internal space inside the inner tube, A catalyst layer formed in the second internal space, A raw material gas introduction line for introducing raw material gas from the lower end side of the first internal space, A raw material gas discharge line is provided, which discharges the raw material gas from the upper end of the first internal space to the outside of the reaction tube body, and whose line end is connected to the upper end of the inner tube. A methanation reactor comprising: a product gas discharge line for discharging the product gas reacted in the catalyst layer from the lower end of the second internal space.

2. A methanation reactor that brings a raw material gas into contact with a catalyst to carry out a methanation reaction, A reaction tube body having an inner tube arranged in the vertical axis direction, an outer tube positioned around the outer circumference of the inner tube, a first internal space between the outer tube and the inner tube, and a second internal space inside the inner tube, A catalyst layer formed in the first internal space, A raw material gas introduction line for introducing raw material gas from the lower end side of the second internal space, A raw material gas discharge line is provided, which discharges the raw material gas from the upper end of the second internal space to the outside of the reaction tube body, and whose line end is connected to the upper end of the outer tube. A methanation reactor comprising: a product gas discharge line for discharging the product gas reacted in the catalyst layer from the lower end of the first internal space;

3. The methanation reactor according to claim 1 or 2, characterized in that the raw material gas discharge line is provided with a heating section and a cooling section.

4. The methanation reactor according to claim 1 or 2, characterized in that the axial length of the outer tube is greater than or equal to the axial length of the catalyst layer.

5. The methanation reactor according to claim 1 or 2, characterized in that a first adjustment valve is installed in the raw material gas introduction line.

6. The aforementioned raw material gas introduction line has a bypass line that bypasses the raw material gas to the raw material gas discharge line, The methanation reactor according to claim 1 or 2, characterized in that a third control valve is installed in the bypass path.

7. The methanation reactor is configured with two or more units in series, The methanation reactor according to claim 1 or 2, characterized in that the product gas discharge line of the upstream methanation reactor is an introduction line that introduces the product gas into the passage between the inner tube and the outer tube of the downstream methanation reactor.

8. The methanation reactor according to claim 7, characterized in that the methanation reactor is configured in parallel.

9. The methanation reaction apparatus according to claim 1 or 2, characterized in that the reaction tube body is a shell and tube.

10. A methanation reaction method using a methanation reactor, The aforementioned methanation reaction apparatus is A reaction tube body having an inner tube arranged in the vertical axis direction, an outer tube positioned around the outer circumference of the inner tube, a first internal space between the outer tube and the inner tube, and a second internal space inside the inner tube, A catalyst layer formed in the second internal space, A raw material gas introduction line for introducing raw material gas from the lower end side of the first internal space, A raw material gas discharge line is provided, which discharges the raw material gas from the upper end of the first internal space to the outside of the reaction tube body, and whose line end is connected to the upper end of the inner tube. The device comprises a product gas discharge line that discharges the product gas generated by the reaction in the catalyst layer from the lower end of the second internal space, A methanation reaction method characterized by bringing the raw material gas into contact with the catalyst layer using the methanation reaction apparatus to carry out a methanation reaction.

11. A methanation reaction method using a methanation reactor, The aforementioned methanation reaction apparatus is A reaction tube body having an inner tube arranged in the vertical axis direction, an outer tube positioned around the outer circumference of the inner tube, a first internal space between the outer tube and the inner tube, and a second internal space inside the inner tube, A catalyst layer formed in the first internal space, A raw material gas introduction line for introducing raw material gas from the lower end side of the second internal space, A raw material gas discharge line is provided, which discharges the raw material gas from the upper end of the second internal space to the outside of the reaction tube body, and whose line end is connected to the upper end of the outer tube. The device comprises a product gas discharge line that discharges the product gas generated by the reaction in the catalyst layer from the lower end of the first internal space, A methanation reaction method characterized by bringing the raw material gas into contact with the catalyst layer using the methanation reaction apparatus to carry out a methanation reaction.

12. The aforementioned methanation reaction apparatus is The aforementioned raw material gas introduction line has a bypass line that bypasses the raw material gas to the raw material gas discharge line, A second regulating valve is installed in the aforementioned raw material gas introduction line. A third regulating valve is installed in the aforementioned bypass path. The methanation reaction method according to claim 10 or 11, characterized in that the third control valve is opened and the second control valve is closed when the methanation reaction apparatus is started.

13. The methanation reaction method according to claim 12, characterized in that the opening degree of the second control valve and the opening degree of the third control valve are controlled according to the temperature of the raw material gas in the raw material gas discharge line.

14. The aforementioned methanation reaction apparatus is Equipped with a heating section or a cooling section, The methanation reaction method according to claim 13, characterized in that the temperature of the raw material gas is controlled by the heating unit or the cooling unit.

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