Ventilation system of a methane oxidation catalyst device and ventilation method of a methane oxidation catalyst device

Abstract

The ventilation system of the methane oxidation catalyst device comprises a methane oxidation catalyst reactor having a methane oxidation catalyst for promoting the oxidation of methane contained in exhaust gas discharged from an internal combustion engine, and a methane oxidation catalyst device including a catalyst casing housing the methane oxidation catalyst reactor, an exhaust gas introduction line for guiding exhaust gas from the internal combustion engine to the methane oxidation catalyst device, and a ventilation device configured to introduce a ventilation gas for ventilating the interior of the methane oxidation catalyst device upstream of the methane oxidation catalyst reactor in the direction of exhaust gas flow.

Description

Technology Field

[0001] The present disclosure relates to a ventilation system and a ventilation method for a methane oxidation catalyst device.

[0002] The present application claims priority based on Japanese patent application No. 2024-030444 filed with the Japan Patent Office on February 29, 2024, and incorporates the contents thereof herein by reference. Background Technology

[0003] Exhaust gas emitted from an internal combustion engine that burns fuel gas containing methane may contain unburned methane (methane slip). In the path of the exhaust gas emitted from the internal combustion engine, a catalyst casing (methane oxidation catalyst device) containing a methane oxidation catalyst capable of oxidizing methane may be formed (see, for example, Patent Document 1). Prior art literature

[0004] Japanese Patent Publication No. 2018-135809 The problem to be solved

[0005] During the operation of the methane oxidation catalyst, the catalyst is maintained at a relatively high temperature because thermal energy from the exhaust gas introduced into the catalyst casing or thermal energy generated by the oxidation reaction of the exhaust gas is transferred to the catalyst. Consequently, when the catalyst is not in use, moisture contained in the exhaust gas remaining inside the catalyst casing may be cooled along with the catalyst by the external air, causing condensation to precipitate. There is a concern that this condensation or certain components contained in the exhaust gas remaining inside the catalyst casing may become factors causing the degradation of the methane oxidation catalyst.

[0006] Taking into account the circumstances described above, at least one embodiment of the present disclosure aims to provide a ventilation system and a ventilation method for a methane oxidation catalyst device capable of suppressing the retention of exhaust gas within the methane oxidation catalyst device. means of solving the problem

[0007] A ventilation system of a methane oxidation catalyst device related to at least one embodiment of the present disclosure is,

[0008] A methane oxidation catalyst device comprising a methane oxidation catalyst reactor having a methane oxidation catalyst for promoting the oxidation of methane contained in exhaust gas emitted from an internal combustion engine, and a catalyst casing housing the methane oxidation catalyst reactor, and

[0009] An exhaust gas introduction line for guiding the exhaust gas from the internal combustion engine to the methane oxidation catalyst device, and

[0010] A ventilation device is provided that is configured to introduce a ventilation gas for ventilating the interior of the methane oxidation catalyst device upstream of the methane oxidation catalyst reactor in the direction of the exhaust gas flow.

[0011] A ventilation method for a methane oxidation catalyst device related to at least one embodiment of the present disclosure is,

[0012] A method for venting a methane oxidation catalyst device comprising a methane oxidation catalyst reactor having a methane oxidation catalyst for promoting the oxidation of methane contained in exhaust gas emitted from an internal combustion engine, and a catalyst casing housing said methane oxidation catalyst reactor.

[0013] The methane oxidation catalyst device is connected to an exhaust gas introduction line for inducing the exhaust gas discharged from the internal combustion engine, and

[0014] The ventilation method of the methane oxidation catalyst device described above is,

[0015] The device comprises a ventilation gas introduction step for ventilating the interior of the methane oxidation catalyst device by introducing a ventilation gas upstream of the methane oxidation catalyst reactor in the direction of the exhaust gas flow. Effects of the invention

[0016] According to at least one embodiment of the present disclosure, a ventilation system and a ventilation method for a methane oxidation catalyst device capable of suppressing the retention of exhaust gas within the methane oxidation catalyst device are provided. Brief explanation of the drawing

[0017] FIG. 1 is a schematic diagram of an internal combustion engine system having a ventilation system of a methane oxidation catalyst device related to one embodiment of the present disclosure. FIG. 2 is a schematic diagram of an internal combustion engine system having a ventilation system of a methane oxidation catalyst device related to one embodiment of the present disclosure. FIG. 3 is a schematic cross-sectional view showing the catalytic casing shown in FIG. 1 as viewed from the downstream side in the direction of exhaust gas flow. FIG. 4 is a schematic cross-sectional view along the direction of exhaust gas flow of a catalyst casing in one embodiment of the present disclosure. FIG. 5 is a control flowchart of a ventilation system of a methane oxidation catalyst device related to one embodiment of the present disclosure. FIG. 6 is an explanatory diagram for explaining an induction fan in one embodiment of the present disclosure. Specific details for implementing the invention

[0018] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc., of the components described as embodiments or illustrated in the drawings are not intended to limit the scope of the present disclosure and are merely illustrative examples.

[0019] In the following description, when simply referred to as the upstream side, it refers to the upstream side following the direction of the main fluid flow in the part or region related to the description of the direction. Likewise, in the following description, when simply referred to as the downstream side, it refers to the downstream side following the direction of the main fluid flow in the part or region related to the description of the direction.

[0020] (Internal combustion engine system)

[0021] FIGS. 1 and FIGS. 2 are each schematic diagrams of an internal combustion engine system (11) equipped with a ventilation system (10) of a methane oxidation catalyst device (1) related to one embodiment of the present disclosure. A ventilation system (10) of a methane oxidation catalyst device (1) related to several embodiments is mounted on an internal combustion engine system (11) equipped with an internal combustion engine (12), as shown in FIGS. 1 and FIGS. 2. The internal combustion engine (12) is configured to be combustible using a fuel gas containing methane as a fuel. Specifically, liquefied natural gas may be used as the fuel gas. When a fuel gas containing methane is used as the fuel for the internal combustion engine (12), the exhaust gas discharged from the internal combustion engine (12) may contain slip methane, which is unburned methane.

[0022] A methane oxidation catalyst device (1) comprises a methane oxidation catalyst reactor (2) and a catalyst casing (3) that accommodates the methane oxidation catalyst reactor (2). The methane oxidation catalyst reactor (2) includes a methane oxidation catalyst for promoting the oxidation of methane (slip methane). The methane oxidation catalyst reactor (2) is configured to oxidize at least a portion of the methane (slip methane) in the exhaust gas using the methane oxidation catalyst and remove it from the exhaust gas. As the methane oxidation catalyst, a catalyst containing a precious metal such as, for example, Pt (platinum) or Ir (iridium) may be used. Additionally, the methane oxidation catalyst reactor (2) may include not only the methane oxidation catalyst but also a catalyst support that supports the methane oxidation catalyst.

[0023] (Ventilation system of methane oxidation catalyst)

[0024] A ventilation system (10) of a methane oxidation catalyst device (1) related to several embodiments comprises, as shown in FIGS. 1 and 2, a methane oxidation catalyst device (1), an exhaust gas introduction line (4), and a ventilation device (5). In the illustrated embodiment, the ventilation system (10) of the methane oxidation catalyst device (1) further comprises a control device (6) for controlling the operation of the ventilation device (5), an exhaust gas discharge line (7), a bypass line (8), and an exhaust gas path switching device (9).

[0025] (Catalyst casing)

[0026] FIGS. 1 and 2 illustrate a cross-section along a first direction (D1), which is the direction of flow of exhaust gas flowing inside the catalyst casing (3). As shown in FIGS. 1 and 2, the catalyst casing (3) includes a cylindrical portion (31) having an internal space (30) through which exhaust gas guided into the catalyst casing (3) flows. In the illustrated embodiment, the cylindrical portion (31) is formed in a rectangular shape extending along the first direction. Specifically, the cylindrical portion (31) has four walls (32, 33, 34, 35) surrounding the four sides of a rectangular cross-section intersecting the first direction on the outer circumference of the internal space (30), and is formed in a rectangular shape having an internal space (30) by these four walls (32, 33, 34, 35). The catalyst casing (3) constitutes the outer shell of the methane oxidation catalyst device (1). The inside of the methane oxidation catalyst device (1) has the same meaning as the inside of the catalyst casing (3), and the outside of the methane oxidation catalyst device (1) has the same meaning as the outside of the catalyst casing (3).

[0027] Exhaust gas flowing inside the catalyst casing (3) (internal space (30)) flows from the upstream side to the downstream side in the first direction (D1). In the illustrated embodiment, exhaust gas flowing inside the catalyst casing (3) flows from the downward side to the upward side in the vertical direction. That is, the first direction in the illustrated embodiment is a direction from the downward side to the upward side in the vertical direction. Also, in the illustrated embodiment, the catalyst casing (3) is arranged in a vertical configuration so that exhaust gas flows along the vertical direction inside the catalyst casing (3), but it may also be arranged in a horizontal configuration so that exhaust gas flows along the horizontal direction inside the catalyst casing (3).

[0028] The methane oxidation catalyst reactor (2) is placed in an internal space (30) and extends along a direction intersecting the first direction (in the illustrated example, a horizontal direction orthogonal to the first direction). The internal space (30) includes two spaces (30A, 30B) partitioned by the methane oxidation catalyst reactor (2). That is, the internal space (30) includes an upstream internal space (30A) upstream of the methane oxidation catalyst reactor (2) in the first direction and a downstream internal space (30B) downstream of the methane oxidation catalyst reactor (2) in the first direction.

[0029] The catalyst casing (3) has an outer circumferential end connected to the end of one side (upstream side in the first direction) of the tubular part (31) and has a one-sided cover part (36) formed in a plate shape extending inward in the diameter direction. The one-sided cover part (36) is the upstream end of the catalyst casing (3) in the first direction, and an exhaust gas inlet (361) is formed in the central part therein for introducing exhaust gas from the outside of the catalyst casing (3) into the upstream internal space (30A).

[0030] The catalyst casing (3) has an outer circumferential end connected to the end of the other side (downstream side in the first direction) of the tubular part (31) and has a plate-shaped cover part (37) formed to extend inward in the diameter direction. The other side cover part (37) is the end of the downstream side in the first direction of the catalyst casing (3), and an exhaust gas outlet (371) is formed in the central part thereof to discharge exhaust gas from the downstream internal space (30B) to the outside of the catalyst casing (3).

[0031] The interior space (30) is a space partitioned by the respective inner wall surfaces of the four walls (32, 33, 34, 35) described above, one side cover (36), and the other side cover (37).

[0032] (Exhaust gas intake line)

[0033] The exhaust gas introduction line (4) forms a path for guiding exhaust gas from the internal combustion engine (12) to the catalyst casing (3) (methane oxidation catalyst device (1)), and is formed, for example, by a pipe through which exhaust gas can flow. One end (upstream end) of the exhaust gas introduction line (4) is connected to an outlet for discharging exhaust gas from the internal combustion engine (12), and the other end (downstream end) is connected to the exhaust gas introduction port (361) of the catalyst casing (3).

[0034] (Exhaust gas discharge line)

[0035] The exhaust gas discharge line (7) forms a flow path for discharging exhaust gas from the catalyst casing (3) (methane oxidation catalyst device (1)), for example, formed by a pipe through which exhaust gas can flow. One end (upstream end) of the exhaust gas discharge line (7) is connected to the exhaust gas outlet (371) of the catalyst casing (3).

[0036] (Bypass line)

[0037] The bypass line (8) forms a flow path to guide exhaust gas from the exhaust gas introduction line (4) to the exhaust gas discharge line (7) by bypassing the catalyst casing (3) (methane oxidation catalyst device (1)), and is formed, for example, by a pipe through which exhaust gas can flow. The exhaust gas introduction line (4) is connected to one end (upstream end) of the bypass line (8) at the upstream connection part (P1) which is the connection part with the bypass line (8). The exhaust gas discharge line (7) is connected to the other end (downstream end) of the bypass line (8) at the downstream connection part (P2) which is the connection part with the bypass line (8).

[0038] (Exhaust gas path switching device)

[0039] The exhaust gas path has a main path passing through a catalyst casing (3) and a bypass path passing through a bypass line (8). The exhaust gas path switching device (9) is configured to switch the path of exhaust gas discharged from an internal combustion engine (12) to a main path or a bypass path.

[0040] In the illustrated embodiment, the exhaust gas path switching device (9) includes a main path side opening / closing damper (91) installed downstream of the upstream connection part (P1) of the exhaust gas introduction line (4) to open and close the exhaust gas introduction line (4), and a bypass path side opening / closing damper (92) installed in the bypass line (8) to open and close the bypass line (8). Each of the main path side opening / closing damper (91) and the bypass path side opening / closing damper (92) may be an opening / closing valve capable of adjusting the opening to fully closed and fully open, or an opening adjustment valve capable of adjusting the opening to fully closed, fully open, and at least one intermediate opening between them.

[0041] By opening the main path side opening / closing damper (91) and closing the bypass path side opening / closing damper (92), exhaust gas discharged from the internal combustion engine (12) passes through the main path where the catalyst casing (3) is formed on the path. By closing the main path side opening / closing damper (91) and closing the bypass path side opening / closing damper (92), exhaust gas discharged from the internal combustion engine (12) bypasses the catalyst casing (3) and passes through the bypass path where the bypass line (8) is formed on the path.

[0042] When the path of the exhaust gas discharged from the internal combustion engine (12) is the main path, the exhaust gas discharged from the internal combustion engine (12) flows through the exhaust gas introduction line (4) and is guided from the exhaust gas introduction port (361) to the upstream internal space (30A). When the exhaust gas guided to the upstream internal space (30A) passes through the methane oxidation catalyst reactor (2), the oxidation of unburned methane that may be contained in the exhaust gas is promoted by the methane oxidation catalyst provided in the methane oxidation catalyst reactor (2). The exhaust gas that has passed through the methane oxidation catalyst reactor (2) is discharged from the exhaust gas outlet (371) to the outside of the catalyst casing (3), specifically to the exhaust gas discharge line (7). When the exhaust gas passes through the methane oxidation catalyst reactor (2), the temperature is raised by the oxidation reaction by the methane oxidation catalyst provided in the methane oxidation catalyst reactor (2).

[0043] In the case where the path of exhaust gas discharged from the internal combustion engine (12) is a bypass path, the exhaust gas discharged from the internal combustion engine (12) flows upstream of the upstream connection part (P1) of the exhaust gas introduction line (4), the bypass line (8), and downstream of the downstream connection part (P2) of the exhaust gas discharge line (7).

[0044] When the operation of the methane oxidation catalyst device (1) is stopped, moisture contained in the exhaust gas remaining inside the catalyst casing (3) may be cooled together with the methane oxidation catalyst reactor (2) by the outside air outside the catalyst casing (3), and condensate may precipitate. There is a concern that this condensate or some components contained in the exhaust gas remaining inside the catalyst casing (3) may become a factor in the deterioration of the methane oxidation catalyst reactor (2). Here, the operation of the methane oxidation catalyst device (1) is stopped when the exhaust gas discharged from the internal combustion engine (12) transitions from a state where it is introduced into the methane oxidation catalyst device (1) to a state where it is not introduced. Specifically, the operation of the methane oxidation catalyst device (1) may be stopped when switching from the main path of the exhaust gas path to a bypass path, or when the operation of the internal combustion engine (12) is stopped.

[0045] (Ventilation device)

[0046] The ventilation device (5) is configured to introduce ventilation gas for ventilating the interior of the catalyst casing (3) upstream of the methane oxidation catalyst reactor (2) in the direction of exhaust gas flow. The ventilation device (5) may introduce ventilation gas into the upstream internal space (30A) (see FIG. 1) or downstream of the upstream connection part (P1) of the exhaust gas introduction line (4). It is preferable that the ventilation device (5) be configured to introduce an amount of ventilation gas greater than the volume of the catalyst casing (3). Specifically, ventilation gas may be air or nitrogen gas, but it is preferable that it be easily available air (for example, outside air at a temperature of 25°C or higher and 35°C or lower).

[0047] (controller)

[0048] The control unit (6) (controller) is an electronic control unit for controlling the operation of the ventilation device (5). The control unit (6) may be composed of a hard relay circuit that can be manufactured relatively cheaply, or may be composed of a microcomputer consisting of a CPU (processor) not shown, memory such as ROM or RAM, a storage device such as an external storage device, an I / O interface, a communication interface, etc. When the control unit (6) is composed of a microcomputer, the processor operates (calculates, etc.) according to the instructions of a program loaded in memory, thereby realizing the control of the operation of the ventilation device (5).

[0049] The control device (6) is configured to obtain information regarding the operating status of the methane oxidation catalyst device (1) from the device constituting the internal combustion engine system (11). In the illustrated embodiment, the control device (6) is configured to receive information regarding the operating status of the methane oxidation catalyst device (1), such as information regarding the opening and closing status of the damper (e.g., a signal from an opening and closing sensor installed in the damper), from the main path side opening and closing damper (91), or from both the main path side opening and closing damper (91) and the bypass path side opening and closing damper (92). The control device (6) is configured to give instructions to the ventilation device (5) to introduce ventilation gas when the methane oxidation catalyst device (1) stops operating, although details will be described later.

[0050] When the operation of the methane oxidation catalyst device (1) is stopped, by introducing a ventilation gas upstream of the methane oxidation catalyst reactor (2) in the direction of exhaust gas flow through the ventilation device (5), the exhaust gas remaining inside the catalyst casing (3) can be discharged to the outside of the catalyst casing (3). The exhaust gas remaining inside the catalyst casing (3) is pushed downstream in the direction of exhaust gas flow by introducing the ventilation gas and is discharged to the outside of the catalyst casing (3) through the exhaust gas outlet (371). By discharging the exhaust gas remaining inside the catalyst casing (3) to the outside of the catalyst casing (3), the deterioration factor of the methane oxidation catalyst reactor (2) can be removed.

[0051] (Ventilation injection device)

[0052] In some embodiments, the ventilation device (5) described above includes a ventilation injection device (51) configured to inject ventilation gas toward the other side (downstream side in the first direction) of the catalyst casing (3) (methane oxidation catalyst device (1)) at one end (upstream side in the first direction) of the catalyst casing (3) (methane oxidation catalyst device (1)). Here, the end of one side of the catalyst casing (3) on which the ventilation injection device (51) is placed means a length position of 0% or more and 20% or less, in the case where the length position of the inner wall surface (362) facing the inner space (30) of the one side cover part (36) in the first direction is defined as 0% and the length position of the inner wall surface (372) facing the inner space (30) of the other side cover part (37) is defined as 100%.

[0053] It is preferable that the ventilation injection device (51) be positioned at a location (in the range of length position from 0% to 10%) close to the inner wall surface (362) of the one-sided cover part (36) in the upstream inner space (30A) so as to ventilate a wide range of the inner space (30) with ventilation gas. In the illustrated embodiment, the center of the methane oxidation catalyst device (1) in the first direction is located on the other-sided cover part (37) side, in the range of length position from 50% to 100%, that is, closer to the center position in the first direction in the inner space (30).

[0054] FIG. 3 is a schematic cross-sectional view showing the catalytic casing (3) shown in FIG. 1 as viewed from the downstream side in the direction of exhaust gas flow. In the embodiment shown in FIG. 1 and FIG. 3, the ventilation injection device (51) includes a plurality of ventilation gas pipes (511) arranged in an upstream internal space (30A) and configured to allow ventilation gas to flow, and a plurality of injection nozzles (512) for injecting ventilation gas. The plurality of injection nozzles (512) are formed in the ventilation gas pipes (511) and have a nozzle for injecting ventilation gas present in the ventilation gas pipes (511) toward the downstream side in the first direction. The ventilation injection device (51), although details will be described later, is connected to a ventilation gas introduction system for introducing ventilation gas into the ventilation injection device (51), and ventilation gas is introduced from the ventilation gas introduction system.

[0055] By using a ventilation injection device (51), ventilation gas is injected from one end (upstream side of the first direction) of the catalyst casing (3) toward the other end (downstream side of the first direction) of the catalyst casing (3), thereby pushing the exhaust gas remaining inside the catalyst casing (3) toward the other end of the catalyst casing (3) and rapidly discharging it to the outside of the catalyst casing (3). In this case, the deterioration factors of the methane oxidation catalyst reactor (2) can be rapidly removed from inside the catalyst casing (3).

[0056] In some embodiments, as shown in FIG. 3, the plurality of ventilation gas pipes (511) described above are extended along a second direction (D2) which is a direction intersecting the first direction, and are spaced apart from other ventilation gas pipes (511) adjacent in the direction intersecting the extension direction of the ventilation gas pipe (511) (direction along the second direction (D2)) when viewed from the first direction or downstream side of the first direction (in the illustrated example, a third direction (D3) which is orthogonal to the second direction (D2)). A plurality of injection nozzles (512) are formed spaced apart from other injection nozzles (512) formed in the same ventilation gas pipe (511) along the extension direction of the ventilation gas pipe (511) (direction along the second direction (D2)).

[0057] In the embodiment shown in FIG. 3, when viewed from the downstream side of the first direction, the extension direction of the ventilation gas pipe (511) is a direction along the second direction from the wall (32) toward the wall (33) facing the wall (32) with an internal space (30) in between. When viewed from the downstream side of the first direction, the wall (32) and the wall (33) extend along the third direction, and the wall (34) and the wall (35) facing the wall (34) with an internal space (30) in between extend along the second direction.

[0058] The ventilation injection device (51), comprising the plurality of ventilation gas pipes (511) and the plurality of injection nozzles (512) described above, can inject ventilation gas over a relatively wide range of the flow path cross-section (see FIG. 3) that is orthogonal to the first direction of the catalyst casing (3), so that ventilation can be performed to every corner of the internal space (30) of the catalyst casing (3). In this case, the deterioration factors of the methane oxidation catalyst reactor (2) can be effectively removed from the interior of the catalyst casing (3).

[0059] (Rotating mechanism)

[0060] FIG. 4 is a schematic cross-sectional view along the flow direction of exhaust gas of a catalyst casing in one embodiment of the present disclosure. In some embodiments, as shown in FIG. 3 and FIG. 4, the ventilation injection device (51) described above includes a rotation mechanism (513) configured to rotate the ventilation gas pipe (511) around the central axis (CA) of the ventilation gas pipe (511). It is preferable that the rotation mechanism (513) be configured to rotate the ventilation gas pipe (511) around the central axis (CA) within a predetermined circumferential range in which the injection direction of the ventilation gas is maintained in a direction toward the downstream side of the first direction.

[0061] In the illustrated embodiment, the rotating mechanism (513) includes a first pulley (515) mounted on a protrusion (514) protruding outside the catalyst casing (3) of the ventilation gas pipe (511), a second pulley (517) connected to the drive shaft of an electric motor (516), and a belt member (518) wound around the first pulley (515) and the second pulley (517). The electric motor (516) rotates the second pulley (517) by power supplied from a power source not illustrated. The ventilation gas pipe (511) rotates around a central axis (CA) by the rotational force of the second pulley (517) transmitted through the belt member (518) and the first pulley (515). A rotating mechanism (513) may be individually formed on each of the plurality of ventilation gas pipes (511), or one rotating mechanism (513) corresponding to two or more plurality of ventilation gas pipes (511) may be formed. The rotating mechanism (513) may be configured to rotate the ventilation gas pipe (511) around a central axis (CA), and is not limited to the illustrated embodiment.

[0062] By rotating the ventilation gas pipe (511) around the central axis (CA) by means of a rotating mechanism (513), a plurality of injection nozzles (512) formed in the ventilation gas pipe (511) can also be rotated around the central axis (CA). By rotating the plurality of injection nozzles (512) around the central axis (CA), ventilation gas can be sprayed toward a relatively wide range of the cross-section of the flow path that is orthogonal to the first direction of the catalyst casing (3). In this case, since the ventilation gas can be widely spread to every corner of the internal space (30) of the catalyst casing (3), the deterioration factors of the methane oxidation catalyst reactor (2) can be more effectively removed from the inside of the catalyst casing (3). In addition, in some other embodiments, the ventilation injection device (51) may be configured not to include a rotating mechanism (513), that is, the ventilation gas tube (511) may not rotate around the central axis (CA).

[0063] (Ventilation gas introduction system)

[0064] In some embodiments, the ventilation device (5) described above includes, in addition to the ventilation injection device (51) described above as shown in FIG. 1, a ventilation storage tank (52) configured to store ventilation gas and a ventilation gas introduction line (53) for discharging ventilation gas from the ventilation storage tank (52) and guiding it to the ventilation injection device (51). The ventilation storage tank (52) has an internal space for storing ventilation gas.

[0065] The ventilation gas introduction line (53) forms a flow path for inducing ventilation gas, for example, formed by a pipe through which ventilation gas can flow. The ventilation gas introduction line (53) has one end (upstream end) connected to a ventilation storage tank (52) and the other end (downstream end) connected to a ventilation injection device (51). Ventilation gas stored in the internal space of the ventilation storage tank (52) is guided to the ventilation injection device (51) through the ventilation gas introduction line (53). In the embodiment shown in FIG. 3, the ventilation gas introduction line (53) includes a main pipe (531) connected to the ventilation storage tank (52) and a plurality of branch pipes (532) branched from the main pipe (531) and connected to corresponding ventilation gas pipes (511).

[0066] In the illustrated embodiment, the ventilation device (5) includes a compressor (54) configured to increase the pressure of the ventilation gas directed to the ventilation injection device (51) to a predetermined pressure or higher, as shown in FIG. 1, and a ventilation gas supply line (55) for directing the ventilation gas compressed in the compressor (54) to a ventilation storage tank (52). The compressor (54) is configured to compress the ventilation gas directed to the compressor (54) from a source of ventilation gas. The ventilation gas supply line (55) forms a flow path for directing the ventilation gas compressed in the compressor (54) to the ventilation storage tank (52), and is formed, for example, by a pipe through which the ventilation gas can flow. The ventilation gas, which has been increased to a predetermined pressure or higher in the compressor (54) through the ventilation gas supply line (55), is stored in the ventilation storage tank (52).

[0067] When external air is used as the ventilation gas injected from the ventilation injection device (51), the exhaust gas present inside the catalyst casing (3) is cooled by the external air injected from the ventilation injection device (51), and there is a possibility that the condensation of moisture inside the catalyst casing (3) may be promoted. When the internal combustion engine (12) uses liquefied natural gas as fuel, a small amount of liquid (oil) fuel may be burned for stable combustion. In this case, the exhaust gas discharged from the internal combustion engine (12) may contain a small amount of sulfur, and if the moisture contained in the exhaust gas condenses, there is a risk that the inside of the methane oxidation catalyst device (1) will be worn or damaged by sulfuric acid corrosion. By increasing the pressure of the ventilation gas by the compressor (54), the flow rate of the ventilation gas injected from the ventilation injection device (51) and flowing inside the catalyst casing (3) can be increased. By increasing the flow rate of the ventilation gas, the exhaust gas remaining inside the catalyst casing (3) (a deterioration factor of the methane oxidation catalyst reactor (2)) can be quickly discharged before the inside of the catalyst casing (3) is cooled by the ventilation gas.

[0068] The amount of ventilation gas supplied by the ventilation injection device (51) (ventilation device (5)) is preferably 3 times or more and 5 times or less the volume of the catalyst casing (3), and is more preferably about 4 times (3.8 times or more and 4.2 times or less) the volume of the catalyst casing (3). In addition, it is desirable to set the flow rate or pressure of the ventilation gas so that ventilation by the ventilation device (5) can be completed in a few seconds.

[0069] In the illustrated embodiment, the ventilation injection device (51) includes a ventilation gas supply valve (56) formed in the ventilation gas introduction line (53) and configured to adjust the flow rate of the ventilation gas flowing through the ventilation gas introduction line (53). The ventilation gas supply valve (56) may be an open / close valve that can be adjusted to fully closed and fully open, or an open / close valve that can be adjusted to fully closed, fully open, and at least one intermediate opening between them. The control device (6) is configured to control the operation of the ventilation device (5) (the timing or amount of ventilation gas injection) by controlling the opening and closing of the ventilation gas supply valve (56).

[0070] Through the ventilation gas introduction line (53), the ventilation gas stored in the ventilation storage tank (52) can be directed to the ventilation injection device (51). In this case, the supply amount of ventilation gas to the ventilation injection device (51) can be made large, and thus the flow rate of the ventilation gas injected from the ventilation injection device (51) can be made large. By increasing the flow rate of the ventilation gas injected from the ventilation injection device (51), the deterioration factors of the methane oxidation catalyst reactor (2) inside the catalyst casing (3) can be more effectively removed. In addition, in some other embodiments, the ventilation device (5) may be configured without the ventilation storage tank (52), for example, with a compressor (54) connected to one end (upstream end) of the ventilation gas introduction line (53).

[0071] (Control flow of the ventilation system)

[0072] FIG. 5 is a control flowchart of a ventilation system of a methane oxidation catalyst device related to one embodiment of the present disclosure. A control device (6) monitors information regarding the operating state of the methane oxidation catalyst device (1) (e.g., information regarding the open / closed state of a damper). When the operating state of the methane oxidation catalyst device (1) is switched from operation to stop operation ("YES" in Step S1), the control device (6) determines whether the state of the ventilation gas is normal (Step S2).

[0073] The control device (6) is configured to acquire information regarding the operating status of the compressor (54). The control device (6) is configured to acquire the pressure of the ventilation gas boosted by the compressor (54). In the illustrated embodiment, the control device (6) is configured to receive information (signal) from the compressor (54) indicating whether the compressor (54) is operating. The control device (6) is configured to receive the measurement result (signal) of a pressure sensor (57) that measures the pressure of the ventilation gas at the downstream side of the ventilation gas flow direction from the compressor (54) and at the upstream side of the ventilation gas flow direction from the ventilation injection device (51). In the embodiment shown in FIG. 1, the pressure sensor (57) is installed in the ventilation storage tank (52) and is configured to measure the pressure inside the ventilation storage tank (52). Additionally, the installation location of the pressure sensor (57) is not limited to the ventilation storage tank (52), and, for example, in the case where the ventilation device (5) is configured not to include the ventilation storage tank (52), it may be installed in the ventilation gas introduction line (53) located downstream of the compressor (54) to measure the pressure inside the ventilation gas introduction line (53).

[0074] If the pressure of the ventilation gas obtained from the pressure sensor (57) does not reach the predetermined pressure, the control device (6) determines that the condition of the ventilation gas is not normal ("NO" in step S2) and issues a start command to the compressor (54) (step S3). After issuing a start command to the compressor (54), the control device (6) again determines whether the condition of the ventilation gas is normal or not (step S2).

[0075] When the pressure of the ventilation gas obtained from the pressure sensor (57) is greater than or equal to a predetermined pressure, the control device (6) determines that the condition of the ventilation gas is normal ("YES" in Step S2) and gives a first opening instruction to the ventilation gas supply valve (56) to increase the opening (in the illustrated example, to open) (Step S4). After the first opening instruction, after a certain period of time has elapsed (Step S5), a second opening instruction is given to the ventilation gas supply valve (56) to decrease the opening (in the illustrated example, to close completely) (Step S6). Additionally, the control device (6) may give a start command to the rotating mechanism (513) when the first opening instruction is given, and give a start stop command to the rotating mechanism (513) when the second opening instruction is given.

[0076] Press-fit fan

[0077] In the above-described embodiments, the ventilation device (5) included a ventilation injection device (51), etc., but instead of the ventilation injection device (51), etc., it may include a forced air fan (58) (see FIG. 2). The forced air fan (58) is installed downstream of the main path side opening / closing damper (91) (exhaust gas path switching device (9)) of the exhaust gas introduction line (4) and is a device for pushing outside air into the catalyst casing (3). The control device (6) is configured to execute a start command for the forced air fan (58) instead of a first degree instruction, and to execute a start / stop command for the forced air fan (58) instead of a second degree instruction. If the ventilation device (5) does not include a compressor (54), the determination of whether the state of the ventilation gas described above is normal or not (step S2) is unnecessary, and the control device (6) issues a start command to the forced draft fan (58) when the operating state of the methane oxidation catalyst device (1) is switched from operation to operation stop ("YES" in step S1).

[0078] According to the above configuration, when the operation of the methane oxidation catalyst device (1) is stopped, outside air is pushed into the catalyst casing (3) by the forced fan (58), thereby forming a flow of gas directed downstream in the direction of exhaust gas flow inside the catalyst casing (3), and exhaust gas remaining inside the catalyst casing (3) is discharged to the outside of the catalyst casing (3). By discharging the exhaust gas remaining inside the catalyst casing (3) to the outside of the catalyst casing (3), the deterioration factor of the methane oxidation catalyst reactor (2) can be eliminated.

[0079] (Yuin Fan)

[0080] FIG. 6 is an explanatory diagram for explaining an induction fan (13) in one embodiment of the present disclosure. In some embodiments, the ventilation system (10) of the methane oxidation catalyst device (1) described above additionally includes an induction fan (13) in addition to the ventilation device (5) described above. The exhaust gas discharge line (7) includes an exhaust side bypass line (14) that bypasses the downstream connection part (P2) of the exhaust gas discharge line (7). The upstream end of the exhaust side bypass line (14) is connected upstream of the downstream connection part (P2) of the exhaust gas discharge line (7), and the downstream end is connected downstream of the downstream connection part (P2) of the exhaust gas discharge line (7). The induction fan (13) is installed in the exhaust-side bypass line (14) and is a device for drawing exhaust gas from the catalytic casing (3) to the exhaust gas discharge line (7). By driving the induction fan (13) to form a flow of exhaust gas from the upstream end to the downstream end of the exhaust-side bypass line (14), exhaust gas is drawn from the inside of the catalytic casing (3) to the exhaust gas discharge line (7). The control device (6) may execute a start command for the induction fan (13) at the first degree instruction and execute a start / stop command for the induction fan (13) at the second degree instruction.

[0081] When the operation of the methane oxidation catalyst device (1) is stopped, exhaust gas is drawn from the catalyst casing (3) to the exhaust gas discharge line (7) by the induction fan (13), thereby promoting the discharge of exhaust gas from the inside of the catalyst casing (3). This allows the deterioration factors of the methane oxidation catalyst reactor (2) to be removed more quickly from the inside of the catalyst casing (3).

[0082] A ventilation method for a methane oxidation catalyst device (1) related to several embodiments includes at least a ventilation gas introduction step for introducing ventilation gas to ventilate the interior of a catalyst casing (3) upstream of the methane oxidation catalyst device (1) in the direction of exhaust gas flow. In the ventilation method of the methane oxidation catalyst device (1), control by the control device (6) described above may be changed to a control device other than the control device (6) or manual operation. Examples of control by this control device (6) include the opening and closing control of the ventilation gas supply valve (56), the driving control of the forced draft fan (58), and the driving control of the induction fan (13).

[0083] When the operation of the methane oxidation catalyst device (1) is stopped, by performing a ventilation gas introduction step in which ventilation gas is introduced upstream of the methane oxidation catalyst device (1) in the direction of exhaust gas flow, the exhaust gas remaining inside the catalyst casing (3) can be discharged to the outside of the catalyst casing (3). By discharging the exhaust gas remaining inside the catalyst casing (3) to the outside of the catalyst casing (3), the deterioration factor of the methane oxidation catalyst reactor (2) can be eliminated.

[0084] In this specification, expressions indicating relative or absolute arrangements such as “in a certain direction,” “along a certain direction,” “parallel,” “orthogonal,” “center,” “concentric,” or “coaxial” are used not only to strictly indicate such arrangements, but also to indicate a state of relative displacement by an angle or distance sufficient to obtain the same function, or a tolerance.

[0085] For example, expressions indicating that things are in an equivalent state, such as "identical," "equivalent," and "homogeneous," are meant to indicate not only a strictly equivalent state, but also a state in which tolerances or differences exist to the extent that the same function is obtained.

[0086] In addition, in this specification, expressions indicating shapes such as square shapes or cylindrical shapes represent not only shapes such as square shapes or cylindrical shapes in a geometrically strict sense, but also shapes including uneven parts or chamfered parts within the scope where the same effect is obtained.

[0087] Furthermore, in this specification, expressions such as “comprising,” “including,” or “having” one component are not exclusive expressions that exclude the existence of other components.

[0088] The present disclosure is not limited to the embodiments described above, and includes forms that are variations of the embodiments described above, or forms that are appropriately combined thereof.

[0089] The contents described in the above-described embodiments are understood, for example, as follows.

[0090] 1) The ventilation system (10) of the methane oxidation catalyst device (1) related to at least one embodiment of the present disclosure is,

[0091] A methane oxidation catalyst device (1) comprising a methane oxidation catalyst reactor (2) having a methane oxidation catalyst for promoting the oxidation of methane contained in exhaust gas discharged from an internal combustion engine (12), and a catalyst casing (3) housing the methane oxidation catalyst reactor (2), and

[0092] An exhaust gas introduction line (4) for inducing the exhaust gas from the internal combustion engine (12) to the methane oxidation catalyst device (1), and

[0093] A ventilation device (5) configured to introduce a ventilation gas for ventilating the interior of the methane oxidation catalyst device (1) upstream of the methane oxidation catalyst reactor (2) in the direction of the exhaust gas flow is provided.

[0094] According to the configuration of 1) above, when the operation of the methane oxidation catalyst device (1) is stopped, by introducing ventilation gas upstream of the methane oxidation catalyst reactor (2) in the direction of exhaust gas flow through the ventilation device (5), the exhaust gas remaining inside the methane oxidation catalyst device (1) can be discharged to the outside of the methane oxidation catalyst device (1). By discharging the exhaust gas remaining inside the methane oxidation catalyst device (1) to the outside of the methane oxidation catalyst device (1), the deterioration factor of the methane oxidation catalyst reactor (2) can be eliminated.

[0095] 2) In some embodiments, as a ventilation system (10) of the methane oxidation catalyst device (1) described in 1) above,

[0096] The above ventilation device (5) is,

[0097] It includes a ventilation injection device (51) configured to inject the ventilation gas toward the other side of the methane oxidation catalyst device (1) at one end of the methane oxidation catalyst device (1).

[0098] According to the configuration of 2) above, by injecting ventilation gas from one end of the methane oxidation catalyst device (1) toward the other end of the methane oxidation catalyst device (1) by means of a ventilation injection device (51), exhaust gas remaining inside the methane oxidation catalyst device (1) can be pushed and flowed toward the other end of the methane oxidation catalyst device (1) and quickly discharged to the outside of the methane oxidation catalyst device (1). In this case, the deterioration factors of the methane oxidation catalyst reactor (2) can be quickly removed from inside the methane oxidation catalyst device (1).

[0099] 3) In some embodiments, as a ventilation system (10) of the methane oxidation catalyst device (1) described in 2) above,

[0100] The above ventilation injection device (51) is,

[0101] A plurality of ventilation gas pipes (511) disposed inside the catalyst casing (3) and configured to allow the ventilation gas to flow, wherein the ventilation gas pipes (511) extend along a direction intersecting the first direction which is the direction of flow of the exhaust gas flowing inside the catalyst casing (3), and, when viewed from the first direction, are spaced apart in a direction intersecting the extension direction of the ventilation gas pipes (511).

[0102] A plurality of injection nozzles (512) for injecting the above ventilation gas are included, wherein a plurality of injection nozzles (512) are formed in the ventilation gas pipe (511) at intervals along the extension direction of the above ventilation gas pipe (511).

[0103] According to the configuration of 3) above, the ventilation injection device (51), which includes a plurality of ventilation gas pipes (511) and a plurality of injection nozzles (512), can inject ventilation gas over a relatively wide range of the cross-section of the flow path perpendicular to the first direction of the catalyst casing (3), thereby allowing ventilation to be performed to every corner of the internal space of the catalyst casing (3). In this case, the deterioration factors of the methane oxidation catalyst reactor (2) can be effectively removed from the interior of the catalyst casing (3).

[0104] 4) In some embodiments, as a ventilation system (10) of the methane oxidation catalyst device (1) described in 3) above,

[0105] The above ventilation injection device (51) is,

[0106] It further includes a rotating mechanism (513) configured to rotate the above ventilation gas pipe (511) around the central axis of the above ventilation gas pipe (511).

[0107] According to the configuration of 4) above, by rotating the ventilation gas pipe (511) around the central axis by means of a rotating mechanism (513), a plurality of injection nozzles (512) formed in the ventilation gas pipe (511) can also be rotated around the central axis. By rotating the plurality of injection nozzles (512) around the central axis, ventilation gas can be sprayed toward a relatively wide range of the cross-section of the flow path that is orthogonal to the first direction of the catalyst casing (3). In this case, since the ventilation gas can be widely spread to every corner of the internal space of the catalyst casing (3), the deterioration factors of the methane oxidation catalyst reactor (2) can be more effectively removed from the inside of the catalyst casing (3).

[0108] 5) In some embodiments, as a ventilation system (10) of a methane oxidation catalyst device (1) described in any one of 2) to 4),

[0109] The above ventilation device (5) is,

[0110] A ventilation storage tank (52) configured to store the above ventilation gas, and

[0111] It further includes a ventilation gas introduction line (53) for discharging the ventilation gas from the ventilation storage tank (52) and guiding it to the ventilation injection device (51).

[0112] According to the configuration of 5) above, ventilation gas stored in the ventilation storage tank (52) can be guided to the ventilation injection device (51) through the ventilation gas introduction line (53). In this case, the supply amount of ventilation gas to the ventilation injection device (51) can be made large, so the flow rate of ventilation gas injected from the ventilation injection device (51) can be made large. By making the flow rate of ventilation gas injected from the ventilation injection device (51) large, the deterioration factors of the methane oxidation catalyst reactor (2) can be more reliably removed from the inside of the catalyst casing (3).

[0113] 6) In some embodiments, as a ventilation system (10) of a methane oxidation catalyst device (1) described in any one of 2) to 5),

[0114] The above ventilation device (5) is,

[0115] It further includes a compressor (54) configured to increase the pressure of the ventilation gas guided by the ventilation injection device (51) to a predetermined pressure or higher.

[0116] According to the configuration of 6) above, by increasing the pressure of the ventilation gas by the compressor (54), the flow rate of the ventilation gas injected from the ventilation injection device (51) and flowing inside the catalyst casing (3) can be increased. By increasing the flow rate of the ventilation gas, the deterioration factors of the methane oxidation catalyst reactor (2) can be removed more quickly from inside the catalyst casing (3).

[0117] 7) In some embodiments, as a ventilation system (10) of the methane oxidation catalyst device (1) described in 1) above,

[0118] The above ventilation device (5) is,

[0119] It includes a forced fan (58) installed in the exhaust gas introduction line (4) to push outside air into the methane oxidation catalyst device (1).

[0120] According to the configuration of 7) above, when the operation of the methane oxidation catalyst device (1) is stopped, the gas present in the exhaust gas introduction line (4) is pushed into the methane oxidation catalyst device (1) by the forced fan (58), thereby forming a gas flow directed downstream in the direction of exhaust gas flow inside the methane oxidation catalyst device (1), and the exhaust gas remaining inside the methane oxidation catalyst device (1) is discharged to the outside of the methane oxidation catalyst device (1). By discharging the exhaust gas remaining inside the methane oxidation catalyst device (1) to the outside of the methane oxidation catalyst device (1), the deterioration factor of the methane oxidation catalyst reactor (2) can be eliminated.

[0121] 8) In some embodiments, as a ventilation system (10) of a methane oxidation catalyst device (1) described in any one of 1) to 7),

[0122] An exhaust gas discharge line (7) for discharging the exhaust gas from the methane oxidation catalyst device (1) and,

[0123] An induction fan (13) is additionally provided to be installed in the exhaust gas discharge line (7) and to draw the exhaust gas from the methane oxidation catalyst device (1) to the exhaust gas discharge line (7).

[0124] According to the configuration of 8) above, when the operation of the methane oxidation catalyst device (1) is stopped, exhaust gas is drawn from the methane oxidation catalyst device (1) to the exhaust gas discharge line (7) by the induction fan (13), thereby promoting the discharge of exhaust gas from inside the methane oxidation catalyst device (1). This allows for the deterioration factors of the methane oxidation catalyst reactor (2) to be removed more quickly from inside the methane oxidation catalyst device (1).

[0125] 9) A ventilation method of a methane oxidation catalyst device (1) related to at least one embodiment of the present disclosure,

[0126] A ventilation method for a methane oxidation catalyst device (1) comprising a methane oxidation catalyst reactor (2) having a methane oxidation catalyst for promoting the oxidation of methane contained in exhaust gas discharged from an internal combustion engine (12), and a catalyst casing (3) housing the methane oxidation catalyst reactor (2).

[0127] The methane oxidation catalyst device (1) is connected to an exhaust gas introduction line (4) for inducing the exhaust gas discharged from the internal combustion engine (12), and

[0128] The ventilation method of the above methane oxidation catalyst device (1) is,

[0129] A ventilation gas introduction step is provided to introduce a ventilation gas for ventilating the interior of the methane oxidation catalyst device (1) upstream of the methane oxidation catalyst reactor (2) in the direction of the exhaust gas flow.

[0130] According to the method of 9) above, when the operation of the methane oxidation catalyst device (1) is stopped, by introducing a ventilation gas upstream of the methane oxidation catalyst reactor (2) in the direction of exhaust gas flow, the exhaust gas remaining inside the methane oxidation catalyst device (1) can be discharged to the outside of the methane oxidation catalyst device (1). By discharging the exhaust gas remaining inside the methane oxidation catalyst device (1) to the outside of the methane oxidation catalyst device (1), the deterioration factor of the methane oxidation catalyst reactor (2) can be eliminated. Explanation of the symbols

[0131] 1: Methane oxidation catalyst device 2 : Methane oxidation catalytic reactor 3: Catalyst casing 4: Exhaust gas intake line 5: Ventilation device 6: Control unit 7: Exhaust gas discharge line 8 : Bypass line 9: Exhaust gas path switching device 10: Ventilation System 11: Internal Combustion Engine System 12: Internal Combustion Engine 13 : Yuin Fan 14: Exhaust side bypass line 30 : Interior space 30A: Upstream internal space 30B: Downstream internal space 31: Tube-shaped part 32, 33, 34, 35: Wall 36 : One-sided cover part 37 : Cover part on the other side 51: Ventilation injection device 52: Ventilation storage tank 53: Ventilation gas introduction line 54 : Compressor 55: Ventilation gas supply line 56: Ventilation gas supply valve 57: Pressure sensor 58 : Press-fit pan 91: Main path-side opening / closing damper 92: Bypass path side opening / closing damper 361: Exhaust gas inlet 362 : One-sided inner wall surface 371: Exhaust gas outlet 372 : Inner wall surface on the other side 511: Ventilation gas pipe 512: Spray nozzle 513: Rotating mechanism D1: First direction D2: Second direction D3: Third direction P1: Upstream connection P2: Downstream connection

Claims

Claim 1 A ventilation system for a methane oxidation catalyst device comprising: a methane oxidation catalyst reactor having a methane oxidation catalyst for promoting the oxidation of methane contained in exhaust gas discharged from an internal combustion engine; a methane oxidation catalyst device including a catalyst casing housing said methane oxidation catalyst reactor; an exhaust gas introduction line for inducing said exhaust gas from said internal combustion engine to said methane oxidation catalyst device; and a ventilation device configured to introduce a ventilation gas for ventilating the interior of said methane oxidation catalyst device upstream of said methane oxidation catalyst reactor in the direction of exhaust gas flow. Claim 2 A ventilation system for a methane oxidation catalyst device according to claim 1, wherein the ventilation device comprises a ventilation injection device configured to inject the ventilation gas toward the other side of the methane oxidation catalyst device at one end of the methane oxidation catalyst device. Claim 3 In claim 2, the ventilation injection device comprises a plurality of ventilation gas pipes arranged inside the catalyst casing and configured to allow the ventilation gas to flow, the plurality of ventilation gas pipes extending along a direction intersecting a first direction which is the direction of flow of the exhaust gas flowing inside the catalyst casing, and spaced apart in a direction intersecting the extension direction of the ventilation gas pipes when viewed from the first direction, and a plurality of injection nozzles for injecting the ventilation gas, the plurality of injection nozzles formed in the ventilation gas pipes spaced apart along the extension direction of the ventilation gas pipes, thereby forming a ventilation system of a methane oxidation catalyst device. Claim 4 In claim 3, the ventilation injection device further comprises a rotating mechanism configured to rotate the ventilation gas pipe around the central axis of the ventilation gas pipe, in a ventilation system of a methane oxidation catalyst device. Claim 5 A ventilation system of a methane oxidation catalyst device according to any one of claims 2 to 4, wherein the ventilation device further comprises a ventilation storage tank configured to store the ventilation gas, and a ventilation gas introduction line for discharging the ventilation gas from the ventilation storage tank and guiding it to the ventilation injection device. Claim 6 A ventilation system of a methane oxidation catalyst device according to any one of claims 2 to 4, wherein the ventilation device further comprises a compressor configured to increase the pressure of the ventilation gas guided to the ventilation injection device to a pressure above a predetermined pressure. Claim 7 A ventilation system for a methane oxidation catalyst device according to claim 1, wherein the ventilation device comprises a forced-in fan installed in the exhaust gas introduction line for pushing outside air into the methane oxidation catalyst device. Claim 8 A ventilation system for a methane oxidation catalyst device according to any one of claims 1 to 4 and 7, further comprising an exhaust gas discharge line for discharging the exhaust gas from the methane oxidation catalyst device and an induction fan installed in the exhaust gas discharge line for drawing the exhaust gas from the methane oxidation catalyst device to the exhaust gas discharge line. Claim 9 A method for ventilating a methane oxidation catalyst device comprising a methane oxidation catalyst reactor having a methane oxidation catalyst for promoting the oxidation of methane contained in exhaust gas discharged from an internal combustion engine, and a catalyst casing housing said methane oxidation catalyst reactor, wherein said methane oxidation catalyst device is connected to an exhaust gas introduction line for inducing said exhaust gas discharged from said internal combustion engine, and said method for ventilating a methane oxidation catalyst device comprises a ventilation gas introduction step for introducing a ventilation gas for ventilating the interior of said methane oxidation catalyst device upstream of said methane oxidation catalyst reactor in the direction of the flow of said exhaust gas.

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