Ventilation system for methane oxidation catalyst device and ventilation method for methane oxidation catalyst device

Abstract

To provide a ventilation system and a ventilation method for a methane oxidation catalyst device capable of preventing stagnation of exhaust gas in the methane oxidation catalyst device.SOLUTION: A ventilation system for a methane oxidation catalyst device includes: a methane oxidation catalyst device that includes a methane oxidation catalyst reaction device having a methane oxidation catalyst for promoting oxidation of methane included in exhaust gas discharged from an internal combustion engine and a catalyst casing that accommodates the methane oxidation catalyst reaction device; 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 ventilation gas for ventilating inside of the methane oxidation catalyst device to an upstream side of the methane oxidation catalyst reaction device in an exhaust gas flowing direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Exhaust gas discharged from an internal combustion engine that burns a fuel gas containing methane as the fuel used may contain unburned methane (methane slip). A catalyst casing (methane oxidation catalyst device) containing a methane oxidation catalyst capable of oxidizing methane may be provided in the path of the exhaust gas discharged from the internal combustion engine (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-135809 Summary of the Invention [Problem to be solved by the invention]

[0004] During use, the methane oxidation catalyst is maintained at a relatively high temperature because thermal energy contained in the exhaust gas introduced into the catalyst casing and thermal energy generated by the oxidation reaction of the exhaust gas are transferred to the catalyst. Meanwhile, when the methane oxidation catalyst is not in use, moisture contained in the exhaust gas remaining inside the catalyst casing may be cooled together with the methane oxidation catalyst by the ambient air outside the catalyst casing, resulting in the deposition of condensed water. This condensed water and some of the components contained in the exhaust gas remaining inside the catalyst casing may cause deterioration of the methane oxidation catalyst.

[0005] In view of the above circumstances, at least one embodiment of the present disclosure aims to provide a ventilation system and ventilation method for a methane oxidation catalyst device that can suppress the accumulation of exhaust gas within the methane oxidation catalyst device. [Means for solving the problem]

[0006] A ventilation system for a methane oxidation catalyst device according to at least one embodiment of the present disclosure includes: a methane oxidation catalyst device including a methane oxidation catalyst reactor equipped with a methane oxidation catalyst for promoting the oxidation of methane contained in exhaust gas discharged from an internal combustion engine, and a catalyst casing accommodating the methane oxidation catalyst reactor; an exhaust gas introduction line for introducing the exhaust gas from the internal combustion engine to the methane oxidation catalyst device; and a ventilation device configured to introduce ventilation gas for ventilating the inside of the methane oxidation catalyst device upstream of the methane oxidation catalyst reactor in the flow direction of the exhaust gas.

[0007] A method for ventilating a methane oxidation catalyst device according to at least one embodiment of the present disclosure includes: A method for ventilating a methane oxidation catalyst device including a methane oxidation catalyst reactor equipped with a methane oxidation catalyst for promoting the oxidation of methane contained in exhaust gas emitted from an internal combustion engine, and a catalyst casing accommodating the methane oxidation catalyst reactor, comprising: the methane oxidation catalyst device is connected to an exhaust gas introduction line for introducing the exhaust gas discharged from the internal combustion engine; The method for ventilating the methane oxidation catalyst device comprises: The method further includes a ventilation gas introduction step of introducing ventilation gas for ventilating the inside of the methane oxidation catalyst device to a position upstream of the methane oxidation catalyst reactor in the flow direction of the exhaust gas. [Effects of the Invention]

[0008] According to at least one embodiment of the present disclosure, a ventilation system and a ventilation method for a methane oxidation catalyst device are provided that can suppress the accumulation of exhaust gas within the methane oxidation catalyst device. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of an internal combustion engine system including a ventilation system for a methane oxidation catalyst device according to an embodiment of the present disclosure. [Figure 2] 1 is a schematic diagram of an internal combustion engine system including a ventilation system for a methane oxidation catalyst device according to an embodiment of the present disclosure. [Figure 3] 2 is a schematic cross-sectional view showing the catalyst casing shown in FIG. 1 as viewed from the downstream side in the flow direction of exhaust gas. FIG. [Figure 4] 1 is a schematic cross-sectional view of a catalyst casing according to an embodiment of the present disclosure, taken along the direction of exhaust gas flow. [Figure 5] FIG. 2 is a control flow diagram of a ventilation system of a methane oxidation catalyst device according to an embodiment of the present disclosure. [Figure 6] FIG. 1 is an explanatory diagram illustrating an induction fan according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] 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 components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure.

[0011] In the following description, when simply referring to the upstream side, it refers to the upstream side along the main flow direction of the fluid in the part or area described in the direction. Similarly, in the following description, when simply referring to the downstream side, it refers to the downstream side along the main flow direction of the fluid in the part or area described in the direction.

[0012] (Internal combustion engine system) 1 and 2 are schematic diagrams of an internal combustion engine system 11 including a ventilation system 10 for a methane oxidation catalyst device 1 according to an embodiment of the present disclosure. As shown in FIGS. 1 and 2, the ventilation system 10 for a methane oxidation catalyst device 1 according to some embodiments is mounted on an internal combustion engine system 11 including an internal combustion engine 12. The internal combustion engine 12 is configured to be able to burn a fuel gas containing methane as a component. Specific examples of the fuel gas include liquefied natural gas. When the methane-containing fuel gas is used as the fuel for the internal combustion engine 12, the exhaust gas emitted from the internal combustion engine 12 may contain slip methane, which is unburned methane.

[0013] The methane oxidation catalyst device 1 includes a methane oxidation catalyst reactor 2 and a catalyst casing 3 that houses 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, for example, a catalyst containing a noble metal such as Pt (platinum) or Ir (iridium) can be used. Note that the methane oxidation catalyst reactor 2 may include not only the methane oxidation catalyst but also a catalyst carrier that supports the methane oxidation catalyst.

[0014] (Ventilation system for methane oxidation catalyst equipment) 1 and 2, a ventilation system 10 for a methane oxidation catalyst device 1 according to some embodiments includes the methane oxidation catalyst device 1, an exhaust gas introduction line 4, and a ventilation device 5. In the illustrated embodiment, the ventilation system 10 for the methane oxidation catalyst device 1 further includes 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.

[0015] (catalyst casing) 1 and 2 show a cross section along a first direction D1, which is the flow direction of exhaust gas flowing inside the catalyst casing 3. As shown in FIGS. 1 and 2, the catalyst casing 3 includes a tubular portion 31 having an internal space 30 through which exhaust gas guided into the catalyst casing 3 flows. In the illustrated embodiment, the tubular portion 31 is formed in a rectangular tubular shape extending along the first direction. Specifically, the tubular portion 31 has four walls 32, 33, 34, and 35 that surround the outer periphery of the internal space 30 and the four sides of a rectangular cross section that intersects with the first direction. These four walls 32, 33, 34, and 35 form the rectangular tubular shape having the internal space 30. The catalyst casing 3 forms the outer shell of the methane oxidation catalyst device 1. The interior of the methane oxidation catalyst device 1 is synonymous with the interior of the catalyst casing 3, and the exterior of the methane oxidation catalyst device 1 is synonymous with the exterior of the catalyst casing 3.

[0016] The 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, the exhaust gas flowing inside the catalyst casing 3 flows vertically from bottom to top. That is, the first direction in the illustrated embodiment is a direction from bottom to top in the vertical direction. Note that in the illustrated embodiment, the catalyst casing 3 is arranged vertically so that the exhaust gas flows vertically inside the catalyst casing 3, but it may also be arranged horizontally so that the exhaust gas flows horizontally inside the catalyst casing 3.

[0017] The methane oxidation catalytic reactor 2 is disposed in an internal space 30 and extends in a direction intersecting the first direction (in the illustrated example, a horizontal direction perpendicular to the first direction). The internal space 30 includes two spaces 30A and 30B partitioned by the methane oxidation catalytic reactor 2. That is, the internal space 30 includes an upstream internal space 30A located upstream of the methane oxidation catalytic reactor 2 in the first direction, and a downstream internal space 30B located downstream of the methane oxidation catalytic reactor 2 in the first direction.

[0018] The catalyst casing 3 has a plate-shaped one-side lid portion 36 whose outer peripheral end is connected to one end (upstream side in the first direction) of the cylindrical portion 31 and which extends radially inward. The one-side lid portion 36 is the upstream end of the catalyst casing 3 in the first direction, and has an exhaust gas inlet 361 formed in its center for introducing exhaust gas from outside the catalyst casing 3 into the upstream internal space 30A.

[0019] The catalyst casing 3 has an other-side lid portion 37 formed in a plate shape extending radially inward, with its outer peripheral end connected to the other-side (downstream side in the first direction) end of the cylindrical portion 31. The other-side lid portion 37 is the downstream end of the catalyst casing 3 in the first direction, and has an exhaust gas outlet 371 formed in its center for discharging exhaust gas from the downstream-side internal space 30B to the outside of the catalyst casing 3.

[0020] The internal space 30 is a space defined by the four walls 32, 33, 34, 35, the one-side lid portion 36, and the other-side lid portion 37, all of which are internal wall surfaces.

[0021] (Exhaust gas introduction line) The exhaust gas introduction line 4 forms a flow 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 piping 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 an exhaust gas introduction port 361 of the catalyst casing 3.

[0022] (Exhaust gas discharge line) The exhaust gas discharge line 7 forms a flow path for discharging exhaust gas from 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 discharge line 7 is connected to the exhaust gas discharge port 371 of the catalyst casing 3.

[0023] (Bypass line) The bypass line 8 forms a flow path for guiding exhaust gas from the exhaust gas inlet line 4 to the exhaust gas discharge line 7, bypassing the catalyst casing 3 (methane oxidation catalyst device 1), and is formed, for example, by piping through which exhaust gas can flow. The exhaust gas inlet line 4 is connected to one end (upstream end) of the bypass line 8 at an upstream connection part P1, which is a 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 a downstream connection part P2, which is a connection part with the bypass line 8.

[0024] (Exhaust gas path switching device) The exhaust gas has a main path that passes through the catalyst casing 3 and a bypass path that passes through the bypass line 8. The exhaust gas path switching device 9 is configured to be able to switch the path of the exhaust gas emitted from the internal combustion engine 12 between the main path and the bypass path.

[0025] In the illustrated embodiment, the exhaust gas route switching device 9 includes a main route side opening / closing damper 91 that is provided downstream of the upstream connection part P1 of the exhaust gas introduction line 4 and opens and closes the exhaust gas introduction line 4, and a bypass route side opening / closing damper 92 that is provided in the bypass line 8 and opens and closes the bypass line 8. Each of the main route side opening / closing damper 91 and the bypass route side opening / closing damper 92 may be an opening / closing valve that can be adjusted to a fully closed position and a fully open position, or may be an opening adjustment valve that can be adjusted to a fully closed position, a fully open position, and at least one intermediate opening position therebetween.

[0026] 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 on which the catalyst casing 3 is provided. By closing the main path side opening / closing damper 91 and opening 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 on which the bypass line 8 is provided.

[0027] When the path of exhaust gas emitted from the internal combustion engine 12 is the main path, the exhaust gas emitted from the internal combustion engine 12 flows through the exhaust gas introduction line 4 and is introduced into the upstream internal space 30A from the exhaust gas introduction port 361. As the exhaust gas introduced into the upstream internal space 30A passes through the methane oxidation catalytic reactor 2, the methane oxidation catalyst provided in the methane oxidation catalytic reactor 2 promotes the oxidation of unburned methane that may be contained in the exhaust gas. The exhaust gas that has passed through the methane oxidation catalytic reactor 2 is discharged from the exhaust gas discharge port 371 to the outside of the catalyst casing 3, specifically, to the exhaust gas discharge line 7. As the exhaust gas passes through the methane oxidation catalytic reactor 2, its temperature is increased by the oxidation reaction caused by the methane oxidation catalyst provided in the methane oxidation catalytic reactor 2.

[0028] When the route of the exhaust gas discharged from the internal combustion engine 12 is a bypass route, the exhaust gas discharged from the internal combustion engine 12 flows upstream of the upstream connection point P1 of the exhaust gas introduction line 4, through the bypass line 8, and downstream of the downstream connection point P2 of the exhaust gas discharge line 7.

[0029] When the methane oxidation catalyst device 1 is shut down, 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, causing condensed water to precipitate. This condensed water and some components contained in the exhaust gas remaining inside the catalyst casing 3 may cause deterioration of the methane oxidation catalyst reactor 2. Here, "shutdown of the methane oxidation catalyst device 1" refers to a transition from a state in which exhaust gas emitted from the internal combustion engine 12 is introduced into the methane oxidation catalyst device 1 to a state in which it is not introduced. Specific examples of times when the methane oxidation catalyst device 1 is shut down include when the exhaust gas route is switched from the main route to a bypass route, and when the internal combustion engine 12 is shut down.

[0030] (Ventilation equipment) The ventilation device 5 is configured to introduce ventilation gas for ventilating the inside of the catalyst casing 3 upstream of the methane oxidation catalytic reactor 2 in the flow direction of the exhaust gas. The ventilation device 5 may introduce the ventilation gas into the upstream internal space 30A (see FIG. 1 ), or may introduce the ventilation gas downstream of the upstream connection part P1 of the exhaust gas inlet line 4. The ventilation device 5 is preferably configured to introduce a volume of ventilation gas equal to or greater than the volume of the catalyst casing 3. Specific examples of ventilation gas include air and nitrogen gas, but readily available air (e.g., outside air at a temperature of approximately 25°C to 35°C) is preferred.

[0031] (Control device) The control device 6 (controller) is an electronic control unit for controlling the operation of the ventilation device 5. The control device 6 may be configured as a hard relay circuit, which can be manufactured relatively inexpensively, or may be configured as a microcomputer including a CPU (processor) (not shown), memories such as ROM and RAM, a storage device such as an external storage device, an I / O interface, a communication interface, etc. When the control device 6 is configured as a microcomputer, the processor operates (performs calculations, etc.) according to instructions of a program loaded into the memory, thereby realizing operation control of the ventilation device 5.

[0032] The control device 6 is configured to acquire information about the operating state of the methane oxidation catalyst device 1 from devices constituting the internal combustion engine system 11. In the illustrated embodiment, the control device 6 receives information about the open / close states of the dampers (e.g., signals from open / close sensors provided in the dampers) from the main path side open / close damper 91 or from both the main path side open / close damper 91 and the bypass path side open / close damper 92 as information about the operating state of the methane oxidation catalyst device 1. As will be described in detail later, the control device 6 is configured to instruct the ventilation device 5 to introduce ventilation gas when the operation of the methane oxidation catalyst device 1 is stopped.

[0033] When the operation of the methane oxidation catalyst device 1 is stopped, the ventilation device 5 introduces ventilation gas upstream of the methane oxidation catalyst reactor 2 in the exhaust gas flow direction, thereby discharging the exhaust gas remaining inside the catalyst casing 3 to the outside of the catalyst casing 3. By introducing the ventilation gas, the exhaust gas remaining inside the catalyst casing 3 is swept downstream in the exhaust gas flow direction and is discharged to the outside of the catalyst casing 3 through the exhaust gas discharge port 371. By discharging the exhaust gas remaining inside the catalyst casing 3 to the outside of the catalyst casing 3, a cause of deterioration of the methane oxidation catalyst reactor 2 can be eliminated.

[0034] (Ventilation injection device) In some embodiments, the ventilation device 5 includes a ventilation injector 51 configured to inject ventilation gas from an end of one side (upstream side in the first direction) of the catalyst casing 3 (methane oxidation catalyst device 1) toward the other side (downstream 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 where the ventilation injector 51 is located means a length position in the range of 0% to 20%, where the length position of the one-side inner wall surface 362 facing the internal space 30 of the one-side lid portion 36 in the first direction is defined as 0% and the length position of the other-side inner wall surface 372 facing the internal space 30 of the other-side lid portion 37 is defined as 100%.

[0035] The ventilation injection device 51 is preferably disposed in the upstream internal space 30A at a position close to the one-side inner wall surface 362 of the one-side lid portion 36 (at a length position in the range of 0% to 10%) so that a wide range of the internal space 30 can be ventilated with ventilation gas. In the illustrated embodiment, the center of the methane oxidation catalyst device 1 in the first direction is located in the length position in the range of 50% to 100%, i.e., closer to the other-side lid portion 37 than the center position of the internal space 30 in the first direction.

[0036] Fig. 3 is a schematic cross-sectional view showing the catalyst casing 3 shown in Fig. 1 as viewed from the downstream side in the flow direction of exhaust gas. In the embodiment shown in Figs. 1 and 3, the ventilation injection device 51 is arranged in the upstream internal space 30A and includes a plurality of ventilation gas pipes 511 configured to allow ventilation gas to flow therethrough, and a plurality of injection nozzles 512 for injecting the ventilation gas. The plurality of injection nozzles 512 are provided in the ventilation gas pipes 511 and have injection holes for injecting the ventilation gas present in the ventilation gas pipes 511 toward the downstream side in the first direction. The ventilation injection device 51, details of which will be described later, is connected to a ventilation gas introduction system for introducing ventilation gas into the ventilation injection device 51, and the ventilation gas is introduced from the ventilation gas introduction system.

[0037] The ventilation injection device 51 injects ventilation gas from an end of one side (upstream side in the first direction) of the catalyst casing 3 toward the other side (downstream side in the first direction) of the catalyst casing 3, thereby forcing the exhaust gas remaining inside the catalyst casing 3 to flow to the other side of the catalyst casing 3 and quickly discharging it to the outside of the catalyst casing 3. In this case, the causes of deterioration of the methane oxidation catalytic reactor 2 can be quickly removed from inside the catalyst casing 3.

[0038] 3, the plurality of ventilation gas pipes 511 extend along a second direction D2 that is a direction intersecting the first direction, and are arranged at intervals between adjacent ventilation gas pipes 511 in a direction (in the illustrated example, a third direction D3 perpendicular to the second direction D2) intersecting the extension direction of the ventilation gas pipe 511 (the direction along the second direction D2) when viewed in the first direction or downstream of the first direction. The plurality of injection nozzles 512 are arranged at intervals between other injection nozzles 512 provided on the same ventilation gas pipe 511 along the extension direction of the ventilation gas pipe 511 (the direction along the second direction D2).

[0039] 3, when viewed from the downstream side in the first direction, the ventilation gas pipe 511 extends in the second direction from the wall 32 to the wall 33 opposite the wall 32 across the internal space 30. When viewed from the downstream side in the first direction, the walls 32 and 33 extend in the third direction, and the wall 34 and the wall 35 opposite the wall 34 across the internal space 30 extend in the second direction.

[0040] The ventilation injection device 51, which includes the above-mentioned multiple ventilation gas pipes 511 and the above-mentioned multiple injection nozzles 512, can inject ventilation gas over a relatively wide range of the flow path cross section (see FIG. 3) perpendicular to the first direction of the catalyst casing 3, thereby ventilating every corner of the internal space 30 of the catalyst casing 3. In this case, factors that cause deterioration of the methane oxidation catalytic reactor 2 can be effectively removed from inside the catalyst casing 3.

[0041] (Rotation mechanism) 4 is a schematic cross-sectional view of a catalyst casing along the flow direction of exhaust gas in one embodiment of the present disclosure. In some embodiments, as shown in FIGS. 3 and 4, the ventilation injection device 51 described above includes a rotation mechanism 513 configured to rotate the ventilation gas pipe 511 about a central axis CA of the ventilation gas pipe 511. The rotation mechanism 513 is preferably configured to rotate the ventilation gas pipe 511 about the central axis CA within a predetermined circumferential range in which the injection direction of the ventilation gas is maintained toward the downstream side of the first direction.

[0042] In the illustrated embodiment, the rotation mechanism 513 includes a first pulley 515 attached to a protrusion 514 of the ventilation gas pipe 511 that protrudes outside the catalyst casing 3, a second pulley 517 connected to a 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 shown). The ventilation gas pipe 511 rotates about the central axis CA by the rotational force of the second pulley 517 transmitted via the belt member 518 and the first pulley 515. A separate rotation mechanism 513 may be provided for each of the multiple ventilation gas pipes 511, or one rotation mechanism 513 may be provided corresponding to two or more multiple ventilation gas pipes 511. The rotation mechanism 513 is not limited to the embodiment shown in the drawings, as long as it is configured to rotate the ventilation gas pipe 511 around the central axis CA.

[0043] By rotating the ventilation gas pipe 511 about the central axis CA using the rotation mechanism 513, the multiple injection nozzles 512 provided on the ventilation gas pipe 511 can also rotate about the central axis CA. By rotating the multiple injection nozzles 512 about the central axis CA, the ventilation gas can be injected toward a relatively wide area of ​​the flow path cross section of the catalyst casing 3 that is perpendicular to the first direction. In this case, the ventilation gas can be distributed to every corner of the internal space 30 of the catalyst casing 3, making it possible to more effectively remove factors that cause deterioration of the methane oxidation catalytic reactor 2 from inside the catalyst casing 3. Note that in some other embodiments, the ventilation injection device 51 may be configured without the rotation mechanism 513, i.e., the ventilation gas pipe 511 may not rotate about the central axis CA.

[0044] (Ventilation gas introduction system) 1, in addition to the ventilation jetting device 51 described above, the ventilation device 5 includes a ventilation storage tank 52 configured to store ventilation gas, and a ventilation gas inlet line 53 for extracting the ventilation gas from the ventilation storage tank 52 and guiding it to the ventilation jetting device 51. The ventilation storage tank 52 has an internal space for storing the ventilation gas.

[0045] The ventilation gas introduction line 53 forms a flow path for guiding the ventilation gas, and is formed, for example, by a pipe through which the ventilation gas can flow. One end (upstream end) of the ventilation gas introduction line 53 is connected to the ventilation storage tank 52, and the other end (downstream end) is connected to the ventilation jetting device 51. The ventilation gas stored in the internal space of the ventilation storage tank 52 is introduced to the ventilation jetting 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 branching from the main pipe 531 and connected to corresponding ventilation gas pipes 511.

[0046] In the illustrated embodiment, as shown in Fig. 1, the ventilation device 5 includes a compressor 54 configured to pressurize the ventilation gas guided to the ventilation jet device 51 to a predetermined pressure or higher, and a ventilation gas supply line 55 for guiding the ventilation gas compressed in the compressor 54 to a ventilation storage tank 52. The compressor 54 is configured to compress the ventilation gas guided to the compressor 54 from a ventilation gas supply source. The ventilation gas supply line 55 forms a flow path for guiding the ventilation gas compressed in the compressor 54 to the ventilation storage tank 52, and is formed by, for example, a pipe through which the ventilation gas can flow. The ventilation storage tank 52 stores the ventilation gas that has been pressurized to a predetermined pressure or higher in the compressor 54 via the ventilation gas supply line 55.

[0047] When outside air is used as the ventilation gas injected from the ventilation injection device 51, the outside air injected from the ventilation injection device 51 may cool the exhaust gas present inside the catalyst casing 3, potentially promoting the condensation of moisture inside the catalyst casing 3. When the internal combustion engine 12 uses liquefied natural gas as its fuel, it may burn a small amount of liquid (oil) fuel to ensure stable combustion. In this case, the exhaust gas emitted from the internal combustion engine 12 may contain a small amount of sulfur. If the moisture contained in the exhaust gas condenses, the interior of the methane oxidation catalyst device 1 may be worn or damaged due to sulfuric acid corrosion. By increasing the pressure of the ventilation gas using the compressor 54, the flow velocity 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 velocity of the ventilation gas, the exhaust gas remaining inside the catalyst casing 3 (a cause of deterioration of the methane oxidation catalyst reactor 2) can be quickly discharged before the interior of the catalyst casing 3 is cooled by the ventilation gas.

[0048] The amount of ventilation gas supplied by the ventilation injection device 51 (ventilation device 5) is preferably 3 to 5 times the volume of the catalyst casing 3, and more preferably about 4 times (3.8 to 4.2 times) the volume of the catalyst casing 3. In addition, the flow rate and pressure of the ventilation gas are preferably set so that ventilation by the ventilation device 5 can be completed within a few seconds.

[0049] In the illustrated embodiment, the ventilation injection device 51 includes a ventilation gas supply valve 56 that is provided in the ventilation gas introduction line 53 and is configured to be able 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 on-off valve that can be adjusted to a fully closed position or a fully open position, or may be an opening adjustment valve that can be adjusted to a fully closed position, a fully open position, and at least one intermediate position therebetween. The control device 6 controls the operation of the ventilation device 5 (the injection timing and supply amount of ventilation gas) by controlling the opening and closing of the ventilation gas supply valve 56.

[0050] The ventilation gas stored in the ventilation storage tank 52 can be introduced to the ventilation injection device 51 via the ventilation gas introduction line 53. In this case, the amount of ventilation gas supplied to the ventilation injection device 51 can be increased, and the flow rate of the ventilation gas injected from the ventilation injection device 51 can be increased. Increasing the flow rate of the ventilation gas injected from the ventilation injection device 51 more reliably removes factors that cause deterioration of the methane oxidation catalytic reactor 2 from inside the catalyst casing 3. Note that in some other embodiments, the ventilation device 5 may be configured not to include the ventilation storage tank 52, for example, configured such that a compressor 54 is connected to one end (upstream end) of the ventilation gas introduction line 53.

[0051] (Ventilation system control flow) 5 is a control flow diagram of a ventilation system for a methane oxidation catalyst device according to an embodiment of the present disclosure. The control device 6 monitors information related to the operating state of the methane oxidation catalyst device 1 (e.g., information related to the open / close state of the damper). When the operating state of the methane oxidation catalyst device 1 switches from operating to stopped ("YES" in step S1), the control device 6 determines whether the state of the ventilation gas is normal (step S2).

[0052] The control device 6 is configured to acquire information regarding the operating state of the compressor 54. The control device 6 is configured to acquire the pressure of the ventilation gas pressurized by the compressor 54. In the illustrated embodiment, the compressor 54 sends information (signal) indicating whether the compressor 54 is operating to the control device 6. The control device 6 is sent a measurement result (signal) from a pressure sensor 57 that measures the pressure of the ventilation gas downstream of the compressor 54 in the ventilation gas flow direction and upstream of the ventilation injection device 51 in the ventilation gas flow direction. In the embodiment shown in FIG. 1, the pressure sensor 57 is provided in the ventilation storage tank 52 and measures the pressure inside the ventilation storage tank 52. Note that the installation location of the pressure sensor 57 is not limited to the ventilation storage tank 52. For example, if the ventilation device 5 does not include the ventilation storage tank 52, the pressure sensor 57 may be installed in the ventilation gas introduction line 53 located downstream of the compressor 54 and measure the pressure inside the ventilation gas introduction line 53.

[0053] If the pressure of the ventilation gas acquired from the pressure sensor 57 is lower than the predetermined pressure, the control device 6 determines that the state of the ventilation gas is not normal ("NO" in step S2) and issues a start-up command to the compressor 54 (step S3). After issuing a start-up command to the compressor 54, the control device 6 again determines whether the state of the ventilation gas is normal or not (step S2).

[0054] When the pressure of the ventilation gas acquired from the pressure sensor 57 is equal to or higher than a predetermined pressure, the control device 6 determines that the state of the ventilation gas is normal ("YES" in step S2), and issues a first opening degree instruction to the ventilation gas supply valve 56 to increase the opening degree (fully open in the illustrated example) (step S4). After issuing the first opening degree instruction, and after a certain period of time has elapsed (step S5), the control device 6 issues a second opening degree instruction to the ventilation gas supply valve 56 to decrease the opening degree (fully closed in the illustrated example) (step S6). Note that the control device 6 may issue a start instruction to the rotation mechanism 513 when issuing the first opening degree instruction, and issue a start / stop instruction to the rotation mechanism 513 when issuing the second opening degree instruction.

[0055] (forced draft fan) In some of the above-described embodiments, the ventilation device 5 includes the ventilation injector 51 and the like. However, the ventilation device 5 may include a forced draft fan 58 (see FIG. 2 ) instead of the ventilation injector 51 and the like. The forced draft fan 58 is provided downstream of the main path-side opening / closing damper 91 (exhaust gas path switching device 9) in the exhaust gas introduction line 4, and is a device for forcing outside air into the catalyst casing 3. The control device 6 issues a start command to the forced draft fan 58 instead of the first opening command, and issues a start / stop command to the forced draft fan 58 instead of the second opening command. If the ventilation device 5 does not include the compressor 54, it is not necessary to determine whether the state of the ventilation gas is normal (step S2). 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 switches from operating to stopped ("YES" in step S1).

[0056] According to the above configuration, when the operation of the methane oxidation catalyst device 1 is stopped, the forced draft fan 58 forces outside air into the catalyst casing 3, thereby forming a gas flow inside the catalyst casing 3 that flows downstream in the direction of the exhaust gas flow, 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, it is possible to eliminate factors that could cause deterioration of the methane oxidation catalyst reactor 2.

[0057] (Attracting fans) FIG. 6 is an explanatory diagram illustrating an induced draft fan 13 according to an embodiment of the present disclosure. In some embodiments, the ventilation system 10 of the methane oxidation catalyst device 1 described above includes not only the ventilation device 5 described above but also an induced draft fan 13. The exhaust gas discharge line 7 includes an exhaust-side bypass line 14 that bypasses the downstream connection point 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 point P2 of the exhaust gas discharge line 7, and the downstream end of the exhaust gas discharge line 7 is connected downstream of the downstream connection point P2 of the exhaust gas discharge line 7. The induced draft fan 13 is provided in the exhaust-side bypass line 14 and is a device for sucking exhaust gas from the catalyst casing 3 into the exhaust gas discharge line 7. By driving the induced draft fan 13 to form a flow of exhaust gas from the upstream end of the exhaust-side bypass line 14 toward the downstream end, exhaust gas is sucked from inside the catalyst casing 3 into the exhaust gas discharge line 7. The control device 6 may be configured to issue a start command to the induced draft fan 13 when the first opening degree command is issued, and to issue a start / stop command to the induced draft fan 13 when the second opening degree command is issued.

[0058] When the methane oxidation catalyst device 1 is shut down, the induced draft fan 13 sucks the exhaust gas from the catalyst casing 3 into the exhaust gas discharge line 7, which promotes the discharge of the exhaust gas from inside the catalyst casing 3. This allows the causes of deterioration of the methane oxidation catalyst reactor 2 to be removed more quickly from inside the catalyst casing 3.

[0059] A method for ventilating a methane oxidation catalyst device 1 according to some embodiments includes at least a ventilation gas introduction step of introducing ventilation gas for ventilating the inside of the catalyst casing 3 upstream of the methane oxidation catalyst device 1 in the flow direction of exhaust gas. In the ventilation method for a methane oxidation catalyst device 1, the control by the control device 6 described above may be replaced by a control device other than the control device 6 or by manual operation. Examples of control by the control device 6 include opening and closing the ventilation gas supply valve 56, driving the forced draft fan 58, and driving the induced draft fan 13.

[0060] When the operation of the methane oxidation catalyst device 1 is stopped, a ventilation gas introduction step is performed in which ventilation gas is introduced upstream of the methane oxidation catalyst device 1 in the exhaust gas flow direction, so that 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, a cause of deterioration of the methane oxidation catalyst reactor 2 can be eliminated.

[0061] In this specification, expressions expressing relative or absolute arrangement such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only express such an arrangement strictly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions such as "identical," "equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. Furthermore, in this specification, expressions representing shapes such as a rectangular shape or a cylindrical shape not only represent rectangular shapes or cylindrical shapes in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained. Furthermore, in this specification, the expressions "comprise," "include," or "have" a component are not exclusive expressions that exclude the presence of other components.

[0062] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0063] The contents of the above-described embodiments can be understood, for example, as follows.

[0064] 1) The ventilation system (10) of the methane oxidation catalyst device (1) according to at least one embodiment of the present disclosure includes: a methane oxidation catalyst device (1) including a methane oxidation catalyst reactor (2) equipped with 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) accommodating the methane oxidation catalyst reactor (2); an exhaust gas introduction line (4) for introducing the exhaust gas from the internal combustion engine (12) to the methane oxidation catalyst device (1); and a ventilation device (5) configured to introduce ventilation gas for ventilating the inside of the methane oxidation catalyst device (1) upstream of the methane oxidation catalyst reactor (2) in the flow direction of the exhaust gas.

[0065] According to the configuration 1), when the methane oxidation catalyst device 1 is stopped, the ventilation device 5 introduces ventilation gas upstream of the methane oxidation catalyst reactor 2 in the exhaust gas flow direction, thereby discharging the exhaust gas remaining inside the methane oxidation catalyst device 1 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, it is possible to eliminate factors that could cause deterioration of the methane oxidation catalyst reactor 2.

[0066] 2) In some embodiments, a ventilation system (10) for the methane oxidation catalyst device (1) described in 1) above, comprising: The ventilation device (5) The methane oxidation catalyst device (1) includes a ventilation injector (51) configured to inject the ventilation gas from one end of the methane oxidation catalyst device (1) toward the other end of the methane oxidation catalyst device (1).

[0067] According to the above configuration 2), the ventilation gas is injected from one end of the methane oxidation catalyst device 1 toward the other end of the methane oxidation catalyst device 1 by the ventilation injection device 51, so that the exhaust gas remaining inside the methane oxidation catalyst device 1 can be pushed to 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 causes of deterioration of the methane oxidation catalyst reactor 2 can be quickly removed from the inside of the methane oxidation catalyst device 1.

[0068] 3) In some embodiments, the ventilation system (10) for the methane oxidation catalyst device (1) described in 2) above, The ventilation injection device (51) a plurality of ventilation gas pipes (511) arranged inside the catalyst casing (3) and configured to allow the ventilation gas to flow therethrough, the plurality of ventilation gas pipes (511) extending along a direction intersecting a first direction which is a flow direction of the exhaust gas flowing inside the catalyst casing (3) and arranged at intervals in a direction intersecting the extending direction of the ventilation gas pipes (511) when viewed from the first direction; and a plurality of injection nozzles (512) for injecting the ventilation gas, the plurality of injection nozzles (512) being provided on the ventilation gas pipe (511) at intervals along the extension direction of the ventilation gas pipe (511).

[0069] According to the above configuration 3), the ventilation injection device (51) including the plurality of ventilation gas pipes (511) and the plurality of injection nozzles (512) can inject the ventilation gas over a relatively wide area of ​​the flow path cross section perpendicular to the first direction of the catalyst casing (3), thereby ventilating every corner of the internal space of the catalyst casing (3). In this case, it is possible to effectively remove factors that cause deterioration of the methane oxidation catalytic reactor (2) from inside the catalyst casing (3).

[0070] 4) In some embodiments, the ventilation system (10) for the methane oxidation catalyst device (1) described in 3) above, The ventilation injection device (51) The ventilation gas pipe (511) further includes a rotation mechanism (513) configured to rotate the ventilation gas pipe (511) about a central axis of the ventilation gas pipe (511).

[0071] According to the configuration 4) above, the rotation mechanism (513) rotates the ventilation gas pipe (511) about its central axis, thereby rotating the multiple injection nozzles (512) provided in the ventilation gas pipe (511) about its central axis. By rotating the multiple injection nozzles (512) about their central axes, the ventilation gas can be injected over a relatively wide area of ​​the flow path cross section of the catalyst casing (3) perpendicular to the first direction. In this case, the ventilation gas can be distributed throughout the interior space of the catalyst casing (3), thereby more effectively removing factors that could cause deterioration of the methane oxidation catalytic reactor (2) from inside the catalyst casing (3).

[0072] 5) In some embodiments, the ventilation system (10) of the methane oxidation catalyst device (1) described in any one of 2) to 4) above, The ventilation device (5) a ventilation storage tank (52) configured to store the ventilation gas; The ventilation system further includes a ventilation gas introduction line (53) for extracting the ventilation gas from the ventilation storage tank (52) and guiding it to the ventilation injection device (51).

[0073] According to the above configuration 5), the ventilation gas stored in the ventilation storage tank (52) can be introduced to the ventilation injection device (51) through the ventilation gas introduction line (53). In this case, the amount of ventilation gas supplied to the ventilation injection device (51) can be increased, and the flow rate of the ventilation gas injected from the ventilation injection device (51) can be increased. Increasing the flow rate of the ventilation gas injected from the ventilation injection device (51) can more reliably remove factors that cause deterioration of the methane oxidation catalytic reactor (2) from inside the catalyst casing (3).

[0074] 6) In some embodiments, the ventilation system (10) of the methane oxidation catalyst device (1) described in any one of 2) to 5) above, The ventilation device (5) The ventilation system further includes a compressor (54) configured to increase the pressure of the ventilation gas introduced to the ventilation jet device (51) to a predetermined pressure or higher.

[0075] According to the above configuration 6), the ventilation gas is pressurized by the compressor (54), thereby increasing the flow velocity of the ventilation gas injected from the ventilation injection device (51) and flowing inside the catalyst casing (3). By increasing the flow velocity of the ventilation gas, deterioration factors of the methane oxidation catalytic reactor (2) can be more quickly removed from the inside of the catalyst casing (3).

[0076] 7) In some embodiments, the ventilation system (10) of the methane oxidation catalyst device (1) described in 1) above, The ventilation device (5) The exhaust gas introduction line (4) includes a forced draft fan (58) for forcing outside air into the methane oxidation catalyst device (1).

[0077] According to the configuration 7) above, when the methane oxidation catalyst device 1 is stopped, the forced draft fan 58 forces the gas present in the exhaust gas introduction line 4 into the methane oxidation catalyst device 1, thereby forming a gas flow inside the methane oxidation catalyst device 1 that flows downstream in the exhaust gas flow direction, and 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, it is possible to eliminate factors that could cause deterioration of the methane oxidation catalyst reactor 2.

[0078] 8) In some embodiments, the ventilation system (10) of the methane oxidation catalyst device (1) described in any one of 1) to 7) above, an exhaust gas discharge line (7) for discharging the exhaust gas from the methane oxidation catalyst device (1); The system further includes an induced draft fan (13) provided in the exhaust gas discharge line (7) for sucking the exhaust gas from the methane oxidation catalyst device (1) into the exhaust gas discharge line (7).

[0079] According to the above configuration 8), when the methane oxidation catalyst device (1) is stopped, the exhaust gas is sucked from the methane oxidation catalyst device (1) into the exhaust gas discharge line (7) by the induced draft fan (13), thereby facilitating the discharge of the exhaust gas from the inside of the methane oxidation catalyst device (1). This makes it possible to more quickly remove factors that cause deterioration of the methane oxidation catalyst reactor (2) from the inside of the methane oxidation catalyst device (1).

[0080] 9) A method for ventilating a methane oxidation catalyst device (1) according to at least one embodiment of the present disclosure, A method for ventilating a methane oxidation catalyst device (1) including a methane oxidation catalyst reactor (2) equipped with a methane oxidation catalyst for promoting oxidation of methane contained in exhaust gas discharged from an internal combustion engine (12), and a catalyst casing (3) that houses the methane oxidation catalyst reactor (2), comprising: the methane oxidation catalyst device (1) is connected to an exhaust gas introduction line (4) for introducing the exhaust gas discharged from the internal combustion engine (12); The ventilation method for the methane oxidation catalyst device (1) comprises: The method includes a ventilation gas introduction step of introducing ventilation gas for ventilating the inside of the methane oxidation catalyst device (1) to a position upstream of the methane oxidation catalyst reactor (2) in the flow direction of the exhaust gas.

[0081] According to the method 9), when the methane oxidation catalyst device 1 is stopped, 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 introducing ventilation gas upstream of the methane oxidation catalyst reactor 2 in the exhaust gas flow direction. By discharging the exhaust gas remaining inside the methane oxidation catalyst device 1 to the outside of the methane oxidation catalyst device 1, the cause of deterioration of the methane oxidation catalyst reactor 2 can be eliminated. [Explanation of symbols]

[0082] 1. Methane oxidation catalyst device 2. Methane oxidation catalytic reactor 3. Catalyst casing 4 Exhaust gas introduction line 5. Ventilation system 6. Control device 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 Attracting Fans 14 Exhaust side bypass line 30 Interior Space 30A Upstream internal space 30B Downstream internal space 31 Cylindrical part 32, 33, 34, 35 Wall 36 One side lid part 37 Other side lid part 51 Ventilation jetting 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 Forced Fan 91 Main path side opening / closing damper 92 Bypass route side opening / closing damper 361 Exhaust gas inlet 362 One side inner wall 371 Exhaust gas outlet 372 Other side inner wall surface 511 Ventilation gas pipes 512 Injection nozzle 513 Rotation Mechanism D1 1st direction D2 2nd direction D3 Third direction P1 Upstream connection P2 downstream connection

Claims

1. a methane oxidation catalyst device including a methane oxidation catalyst reactor equipped with a methane oxidation catalyst for promoting the oxidation of methane contained in exhaust gas discharged from an internal combustion engine, and a catalyst casing accommodating the methane oxidation catalyst reactor; an exhaust gas introduction line for introducing the exhaust gas from the internal combustion engine to the methane oxidation catalyst device; a ventilation device configured to introduce ventilation gas for ventilating the inside of the methane oxidation catalyst device upstream of the methane oxidation catalyst reactor in the flow direction of the exhaust gas, Ventilation system for methane oxidation catalyst equipment.

2. The ventilation device includes: a ventilation injector configured to inject the ventilation gas from one end of the methane oxidation catalyst device toward the other end of the methane oxidation catalyst device; A ventilation system for a methane oxidation catalyst device according to claim 1.

3. The ventilation injection device is 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 flow direction of the exhaust gas flowing inside the catalyst casing, and arranged at intervals in a direction intersecting the extension direction of the ventilation gas pipes when viewed from the first direction; a plurality of injection nozzles for injecting the ventilation gas, the plurality of injection nozzles being provided on the ventilation gas pipe at intervals along the extension direction of the ventilation gas pipe; The ventilation system for a methane oxidation catalyst device according to claim 2.

4. The ventilation injection device is a rotation mechanism configured to rotate the ventilation gas pipe about a central axis of the ventilation gas pipe. The ventilation system for the methane oxidation catalyst device according to claim 3.

5. The ventilation device includes: a ventilation storage tank configured to store the ventilation gas; and a ventilation gas introduction line for extracting the ventilation gas from the ventilation storage tank and guiding it to the ventilation injection device. A ventilation system for a methane oxidation catalyst device according to any one of claims 2 to 4.

6. The ventilation device includes: Further comprising a compressor configured to pressurize the ventilation gas introduced into the ventilation injection device to a predetermined pressure or higher. A ventilation system for a methane oxidation catalyst device according to any one of claims 2 to 4.

7. The ventilation device includes: a forced draft fan provided in the exhaust gas introduction line for forcing outside air into the methane oxidation catalyst device; A ventilation system for a methane oxidation catalyst device according to claim 1.

8. an exhaust gas discharge line for discharging the exhaust gas from the methane oxidation catalyst device; an induced draft fan provided in the exhaust gas discharge line for sucking the exhaust gas from the methane oxidation catalyst device into the exhaust gas discharge line; A ventilation system for a methane oxidation catalyst device according to any one of claims 1 to 4 and 7.

9. A method for ventilating a methane oxidation catalyst device including a methane oxidation catalyst reactor equipped with a methane oxidation catalyst for promoting the oxidation of methane contained in exhaust gas emitted from an internal combustion engine, and a catalyst casing accommodating the methane oxidation catalyst reactor, comprising: the methane oxidation catalyst device is connected to an exhaust gas introduction line for introducing the exhaust gas discharged from the internal combustion engine; The method for ventilating the methane oxidation catalyst device comprises: a ventilation gas introduction step of introducing ventilation gas for ventilating the inside of the methane oxidation catalyst device to a side upstream of the methane oxidation catalyst reactor in a flow direction of the exhaust gas, A method for ventilating a methane oxidation catalyst device.

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