Engine system and ship

Abstract

An engine system is provided with: an engine driven by methane as a fuel; a supercharger driven by exhaust gas discharged from an exhaust part of the engine to supply air to the engine; an exhaust pipe through which exhaust gas exhausted from the supercharger flows; a first oxidation treatment unit into which the exhaust gas is introduced via an exhaust pipe and which houses a first methane oxidation catalyst; a supercharger bypass pipe that bypasses the supercharger and merges a portion of the exhaust gas discharged from the exhaust section with the discharge pipe; and a second oxidation treatment unit that is provided midway along the supercharger bypass pipe and houses a second methane oxidation catalyst.

Description

Technical Field

[0001] The present disclosure relates to an engine system and a ship.

[0002] This application claims priority to Japanese Patent Application No. 2022-159920 filed in Japan on October 4, 2022, the contents of which are incorporated herein by reference. Background Art

[0003] There is known a catalytic converter that oxidizes methane contained in the exhaust gas of an engine. In the case of an engine system equipped with a supercharger, such a catalytic converter is often arranged downstream of the supercharger in the exhaust direction of the exhaust gas.

[0004] Patent document 1 discloses an engine system (reciprocating piston internal combustion engine) having an engine, a supercharger (exhaust turbocharger) and a catalytic converter. The supercharger is driven by the exhaust gas of the engine to supply air to the engine. A pipeline having a catalytic converter is provided between the engine and the supercharger. The exhaust gas of the engine passes through the pipeline having the catalytic converter. The catalytic converter is a methane oxidation catalytic converter, which oxidizes the methane contained in the exhaust gas.

[0005] Prior art literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2015-214970 Summary of the invention

[0007] Problems to be solved by the invention

[0008] However, when methane is used as the fuel of the engine, the exhaust gas may contain unburned components of methane. Therefore, before the exhaust gas is discharged into the atmosphere, the unburned components of methane contained in the exhaust gas need to be oxidized by a methane oxidation catalyst. On the other hand, in an engine system equipped with a supercharger, it is desirable to efficiently drive the supercharger using the exhaust gas discharged from the engine.

[0009] In contrast, in the structure described in Patent Document 1, when gas is used as fuel, exhaust gas discharged from the engine is supplied to the supercharger via a catalytic converter. When the exhaust gas passes through the catalytic converter, the exhaust gas contacts the methane oxidation catalyst in the catalytic converter, thereby oxidizing the methane contained in the exhaust gas. The catalytic converter becomes a flow path resistance to the flow of the exhaust gas, so the exhaust gas that reaches the supercharger via the catalytic converter generates a pressure loss, resulting in a decrease in the driving efficiency of the supercharger.

[0010] The present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to provide an engine system and a ship capable of satisfactorily oxidizing unburned components of methane contained in exhaust gas and suppressing a decrease in driving efficiency of a turbocharger.

[0011] Means for solving problems

[0012] In order to solve the above-mentioned problems, the engine system disclosed in the present invention comprises: an engine, a supercharger, an exhaust pipe, a first oxidation treatment unit, a supercharger bypass pipe and a second oxidation treatment unit. The above-mentioned engine is driven by methane as fuel. The above-mentioned supercharger is driven by the exhaust gas discharged from the exhaust part of the above-mentioned engine, thereby supplying air to the above-mentioned engine. The above-mentioned exhaust pipe is for the exhaust gas discharged from the above-mentioned supercharger to circulate. The above-mentioned first oxidation treatment unit is introduced into the above-mentioned exhaust gas via the above-mentioned exhaust pipe. The above-mentioned first oxidation treatment unit accommodates a first methane oxidation catalyst. The above-mentioned supercharger bypass pipe allows a part of the above-mentioned exhaust gas discharged from the above-mentioned exhaust part to bypass the above-mentioned supercharger and merge with the above-mentioned exhaust pipe. The above-mentioned second oxidation treatment unit is arranged in the middle of the above-mentioned supercharger bypass pipe. The above-mentioned second oxidation treatment unit accommodates a second methane oxidation catalyst.

[0013] The ship of the present disclosure includes the engine system as described above.

[0014] [Effects of the invention]

[0015] According to the engine system and the ship of the present disclosure, it is possible to satisfactorily oxidize the unburned components of methane contained in the exhaust gas and suppress a decrease in the driving efficiency of the supercharger. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a side view of a ship equipped with the engine system according to the first embodiment of the present disclosure.

[0017] Figure 2 It is a diagram showing the configuration of an engine system according to the first embodiment of the present disclosure.

[0018] Figure 3 This is a diagram showing an example of the relationship between the exhaust gas temperature and the methane oxidation rate in the first methane oxidation catalyst and the second methane oxidation catalyst included in the engine system according to the first embodiment of the present disclosure.

[0019] Figure 4 This is a diagram showing the flow of exhaust gas when methane is used as fuel in the engine system according to the first embodiment of the present disclosure.

[0020] Figure 5 This is a diagram showing the flow of exhaust gas when heavy oil is used as fuel in the engine system according to the first embodiment of the present disclosure.

[0021] Figure 6 It is a diagram showing a configuration of an engine system according to a second embodiment of the present disclosure. DETAILED DESCRIPTION

[0022] <First Embodiment>

[0023] Below, refer to Figure 1 to Figure 6 An engine system and a ship according to an embodiment of the present disclosure will be described.

[0024] (Ship structure)

[0025] like Figure 1 As shown, the ship 1 of the first embodiment includes at least a hull 2 ​​and an engine system 10A. Examples of the ship 1 include bulk carriers, carriers of liquefied gas such as liquefied natural gas (LNG), carbon dioxide, and ammonia, ferries, RO-RO ships (Roll-on / Roll-off ships), PCTCs (Pure Car & Truck Carriers), passenger ships, and the like.

[0026] (Structure of the hull)

[0027] The hull 2 ​​has a pair of side panels 3A, 3B forming its outer shell, a bottom 4, an upper deck 5 and a bottom deck 6. The side panels 3A, 3B have a pair of side outer panels forming the port and starboard sides, respectively. The bottom 4 has a bottom outer panel connecting these side panels 3A, 3B. Through this pair of side panels 3A, 3B and the bottom 4, the outer shell of the hull 2 ​​forms a U-shape on a cross section perpendicular to the bow and stern direction Da. The upper deck 5 illustrated in the first embodiment is a full-through deck exposed to the outside. The bottom deck 6 is arranged in the hull 2 ​​and constitutes a double bottom together with the bottom outer panel. On the hull 2, for example, an upper structure 7 having a living area is formed on the upper deck 5 on the stern 2b side. In addition, the position and size of the upper structure 7 can be appropriately changed.

[0028] (Structure of the engine system)

[0029] Figure 2 It is a diagram showing the configuration of an engine system according to the first embodiment of the present disclosure.

[0030] The engine system 10A is provided in the hull 2 ​​.

[0031] like Figure 2 As shown, the engine system 10A mainly includes an engine 20A, a supercharger 30 , a first oxidation treatment unit 40 , and a second oxidation treatment unit 50 .

[0032] The engine 20A is provided in the hull 2. The engine 20A can be exemplified by a main engine that generates a driving force for propelling the hull 2 ​​or an engine that drives a generator that supplies power to the hull 2. The engine 20A is driven by burning fuel. The engine 20A discharges exhaust gas generated by burning fuel. The engine 20A used in the first embodiment can switch between methane and heavy oil as fuel. As heavy oil, A heavy oil, C heavy oil, etc. can be exemplified.

[0033] The engine 20A includes an engine body 21 and an exhaust section 22. The engine body 21 includes, for example, a plurality of cylinders (not shown). A mixture of fuel and air is introduced from the outside into each cylinder of the engine body 21 via an intake section (not shown). The mixture burns in each cylinder. The engine body 21 is driven by the combustion of the mixture in each cylinder. In addition, the engine body 21 discharges exhaust gas generated by the combustion of the mixture in each cylinder to the outside via the exhaust section 22.

[0034] The exhaust section 22 discharges exhaust gas from each cylinder of the engine body 21 to the supercharger 30 and the first oxidation treatment section 40. The exhaust section 22 includes a connecting pipe 23 and a manifold 24. The connecting pipes 23 are provided corresponding to each of the plurality of cylinders. Each connecting pipe 23 connects an exhaust port (not shown) of each cylinder to the manifold 24. Exhaust gas flows from the plurality of connecting pipes 23 into the manifold 24. The manifold 24 collects exhaust gas discharged from the plurality of connecting pipes 23 and sends it to the supercharger 30 and the first oxidation treatment section 40.

[0035] The supercharger 30 is connected to the end of the manifold 24 on the downstream side of the exhaust gas flow direction. A portion of the exhaust gas flowing in the manifold 24 is introduced into the supercharger 30. The supercharger 30 has a compressor (not shown) and an exhaust turbine (not shown) for supplying air to the engine 20A. The exhaust turbine (not shown) of the supercharger 30 converts the energy of the exhaust gas discharged from the exhaust section 22 into rotational energy. The compressor (not shown) is driven by the rotational energy. The exhaust gas passing through the supercharger 30 is discharged to the exhaust pipe 102.

[0036] The exhaust pipe 102 forms a flow path for guiding the exhaust gas discharged from the supercharger 30. That is, the exhaust gas discharged from the supercharger 30 flows through the exhaust pipe 102. One end of the exhaust pipe 102 is connected to the exhaust port (not shown) of the supercharger 30. The exhaust pipe 102 illustrated in the first embodiment extends from the supercharger 30 to the upper side in the vertical direction Dv. The other end of the exhaust pipe 102 is connected to the first oxidation treatment unit 40.

[0037] The first oxidation treatment unit 40 performs a process for oxidizing methane contained in the exhaust gas. The exhaust gas is introduced into the first oxidation treatment unit 40 via the exhaust pipe 102. The exhaust gas introduced into the first oxidation treatment unit 40 includes at least the exhaust gas discharged from the supercharger 30. The first oxidation treatment unit 40 includes a housing 41 and a first methane oxidation catalyst 42.

[0038] The housing 41 forms the outer shell of the first oxidation treatment unit 40. In the first embodiment, the housing 41 extends in the vertical direction Dv. The other end of the exhaust pipe 102 is connected to the lower end of the housing 41. On the other hand, the exhaust pipe 43 is connected to the upper end of the housing 41. The exhaust pipe 43 reaches Figure 1 The ventilator 9 shown in the first embodiment is provided on the upper deck 5 on the stern 2b side of the hull 2, and has a cylindrical shape extending in the up-down direction Dv, and extends so as to protrude upward from the upper deck 5.

[0039] like Figure 2 As shown, the first methane oxidation catalyst 42 is accommodated in the housing 41. The first methane oxidation catalyst 42 oxidizes the unburned portion of methane contained in the exhaust gas. The first methane oxidation catalyst 42 includes, for example, a catalyst carrier and an active component composed of palladium particles fixed to the catalyst carrier.

[0040] The second oxidation treatment unit 50 is provided in the middle of the supercharger bypass pipe 103. The second oxidation treatment unit 50 performs a process of oxidizing methane contained in the exhaust gas flowing through the supercharger bypass pipe 103.

[0041] The supercharger bypass pipe 103 allows a portion of the exhaust gas discharged from the exhaust section 22 to bypass the supercharger 30 and merge with the exhaust pipe 102. The first end 103a of the supercharger bypass pipe 103 is connected to the exhaust section 22. The first end 103a is connected to the downstream side of the flow direction of the exhaust gas in the manifold 24 than the position where the plurality of connecting pipes 23 are connected to the manifold 24 of the exhaust section 22. The second end 103b of the supercharger bypass pipe 103 is connected to the exhaust pipe 102.

[0042] The pipe diameter (inner diameter) D2 of the supercharger bypass pipe 103 is set based on the flow rate of exhaust gas required to drive the supercharger 30 in order to feed air to the engine 20A. The flow rate of exhaust gas required to drive the supercharger 30 is determined based on the set value (design value) of the flow rate of air to be fed to the engine 20A. Exhaust gas of a flow rate that is the difference between the flow rate of exhaust gas discharged from the engine 20A and the flow rate of exhaust gas required to drive the supercharger 30 is introduced into the supercharger bypass pipe 103. In other words, the remaining part of the exhaust gas required for the supercharger 30 in the exhaust gas discharged from the engine 20A is introduced into the supercharger bypass pipe 103. Therefore, the pipe diameter (inner diameter) D2 of the supercharger bypass pipe 103 is smaller than the pipe diameter D1 of the exhaust pipe 102.

[0043] The exhaust gas exhausted from the exhaust portion 22 of the engine 20A is introduced into the second oxidation treatment section 50 via the supercharger bypass pipe 103. The second oxidation treatment section 50 includes a housing 51 and a second methane oxidation catalyst 52.

[0044] The housing 51 forms an outer shell of the second oxidation treatment unit 50. In the first embodiment, the housing 51 extends in the vertical direction Dv. The upstream portion 103p of the supercharger bypass pipe 103 is connected to the lower end of the housing 51. The downstream portion 103q of the supercharger bypass pipe 103 is connected to the upper end of the housing 51.

[0045] The second methane oxidation catalyst 52 is accommodated in the housing 51. The second methane oxidation catalyst 52 oxidizes the unburned portion of methane contained in the exhaust gas. The second methane oxidation catalyst 52 includes, for example, a catalyst carrier and an active component composed of palladium particles fixed to the catalyst carrier. In the first embodiment, the first methane oxidation catalyst 42 and the second methane oxidation catalyst 52 contain the same active component.

[0046] Figure 3 This is a diagram showing an example of the relationship between the exhaust gas temperature and the methane oxidation rate in the first methane oxidation catalyst and the second methane oxidation catalyst included in the engine system according to the first embodiment of the present disclosure.

[0047] like Figure 3 As shown, in the first methane oxidation catalyst 42 and the second methane oxidation catalyst 52, the higher the temperature of the exhaust gas, the higher the oxidation rate of methane. Therefore, it is preferable to perform the oxidation treatment of the unburned components of methane in a region where the temperature of the exhaust gas is as high as possible. In the first embodiment, by making the concentration of the catalyst component of the second methane oxidation catalyst 52 higher than the concentration of the catalyst component of the first methane oxidation catalyst 42, the oxidation treatment efficiency of methane can be further improved, and the total amount of active components of the first methane oxidation catalyst 42 and the second methane oxidation catalyst 52 can be reduced.

[0048] In addition, if Figure 2 As shown in FIG. 1 , a valve 60A is provided in an upstream portion 103p of the supercharger bypass pipe 103, which is located upstream of the second oxidation treatment unit 50 in the flow direction of the exhaust gas. The valve 60A opens and closes the flow path of the exhaust gas from the exhaust unit 22 to the supercharger bypass pipe 103. The valve 60A adjusts the opening degree according to the exhaust gas required amount to the supercharger 30.

[0049] In addition, the engine system 10A of the first embodiment further includes a first oxidation treatment unit bypass pipe 105 and a switching unit 110. The first oxidation treatment unit bypass pipe 105 forms a flow path for exhaust gas that bypasses the first oxidation treatment unit 40. One end of the first oxidation treatment unit bypass pipe 105 branches from the exhaust pipe 102. The other end of the first oxidation treatment unit bypass pipe 105 merges with the exhaust pipe 43.

[0050] The switching unit 110 switches the introduction destination of the exhaust gas discharged from the supercharger 30 between the exhaust pipe 102 and the first oxidation treatment unit bypass pipe 105. The switching unit 110 includes a first switching valve 111 and a second switching valve 112. The first switching valve 111 is disposed in the exhaust pipe 102 between a portion connected to one end of the first oxidation treatment unit bypass pipe 105 and the first oxidation treatment unit 40. The second switching valve 112 is provided in the first oxidation treatment unit bypass pipe 105. The first switching valve 111 and the second switching valve 112 can also be opened and closed by remote operation or the like.

[0051] The engine system 10A in the first embodiment includes the first oxidation treatment unit bypass pipe 105 and the switching unit 110 as described above, thereby enabling the exhaust gas introduction destination to be switched to the first oxidation treatment unit bypass pipe 105 instead of the first oxidation treatment unit 40. As a result, the exhaust gas discharged from the supercharger 30 to the exhaust pipe 102 can bypass the first oxidation treatment unit 40 and reach the exhaust pipe 43.

[0052] like Figure 1 , Figure 2 As shown, the engine 20A, the supercharger 30 and the second oxidation treatment unit 50 in the above-mentioned engine system 10A are housed in, for example, an engine room 2k provided in the hull 2. The exhaust pipe 102 and the downstream portion 103q of the supercharger bypass pipe 103 extending upward from the second oxidation treatment unit 50 penetrate the deck 8 provided above the engine room 2k and extend to the upper layer in the hull 2. The first oxidation treatment unit 40 illustrated in this embodiment is arranged in the upper engine room 2j formed on the upper side of the deck 8. However, the arrangement of the first oxidation treatment unit 40 is not limited to the case where it is arranged in the upper engine room 2j.

[0053] Figure 4This is a diagram showing the flow of exhaust gas when methane is used as fuel in the engine system according to the first embodiment of the present disclosure.

[0054] like Figure 4 As shown, in the engine system 10A, when methane is used as the fuel of the engine 20A, the valve 60A and the first switching valve 111 are opened, and the second switching valve 112 is closed. A part of the exhaust gas discharged from the exhaust section 22 of the engine 20A is introduced into the supercharger 30 from the manifold 24 of the exhaust section 22. The supercharger 30 is driven by the exhaust gas introduced into the supercharger 30, and air is supplied to the engine 20A. The exhaust gas discharged from the supercharger 30 to the exhaust pipe 102 is operated to supply air to the engine 20A, and the temperature is reduced.

[0055] In addition, the remaining part (remaining amount) of the exhaust gas discharged from the exhaust section 22 of the engine 20A flows from the manifold 24 into the supercharger bypass pipe 103. The exhaust gas flowing into the supercharger bypass pipe 103 is introduced into the second oxidation treatment section 50. In the second oxidation section 50, the second methane oxidation catalyst 52 performs oxidation treatment on the unburned part of methane contained in the introduced exhaust gas. Due to the oxidation treatment of the unburned component of methane in the second oxidation treatment section 50, the temperature of the exhaust gas passing through the second oxidation treatment section 50 rises.

[0056] The exhaust gas that has passed through the supercharger 30 and the exhaust gas that has passed through the second oxidation treatment unit 50 merge in the exhaust pipe 102. The exhaust gas that has passed through the second oxidation treatment unit 50 has its temperature increased by oxidation treatment, so the temperature of the mixed gas (exhaust gas) formed by mixing the exhaust gas that has passed through the supercharger 30 and the exhaust gas that has passed through the second oxidation treatment unit 50 is higher than the temperature of the exhaust gas discharged from the supercharger 30 alone.

[0057] The exhaust gas having a temperature increased in this way is introduced from the exhaust pipe 102 into the first oxidation treatment section 40. In the first oxidation section 40, the unburned portion of methane contained in the introduced exhaust gas is oxidized by the first methane oxidation catalyst 42. The exhaust gas having passed through the first oxidation treatment section 40 is discharged from the ventilator 9 into the atmosphere through the exhaust pipe 43.

[0058] Figure 5 This is a diagram showing the flow of exhaust gas when heavy oil is used as fuel in the engine system according to the first embodiment of the present disclosure.

[0059] like Figure 5As shown, in the engine system 10A, when heavy oil is used as the fuel of the engine 20A, the valve 60A and the first switching valve 111 are closed, and the second switching valve 112 is opened. All the exhaust gas discharged from the exhaust section 22 of the engine 20A is introduced into the supercharger 30 from the manifold 24 of the exhaust section 22. The supercharger 30 is driven by the exhaust gas introduced into the supercharger 30, and air is supplied to the engine 20A. The exhaust gas discharged from the supercharger 30 flows from the exhaust pipe 102 into the first oxidation treatment section bypass pipe 105, bypasses the first oxidation treatment section 40, and is discharged from the ventilator 9 to the atmosphere through the exhaust pipe 43.

[0060] (Effect)

[0061] In the engine system 10A and the ship 1 of the first embodiment, the exhaust gas discharged from the exhaust section 22 of the engine 20A is sent to the supercharger 30 and the supercharger bypass pipe 103. The supercharger 30 is driven by the exhaust gas to supply air to the engine 20A. The exhaust gas discharged from the supercharger 30 flows through the exhaust pipe 102. The exhaust gas discharged from the supercharger 30 to the exhaust pipe 102 is lowered in temperature by performing the operation for supplying air to the engine 20A.

[0062] On the other hand, the exhaust gas sent to the supercharger bypass pipe 103 is introduced into the second oxidation treatment section 50. The second oxidation treatment section 50 performs oxidation treatment on the unburned components of methane contained in the introduced exhaust gas by the second methane oxidation catalyst 52. By performing oxidation treatment on the unburned components of methane, the temperature of the exhaust gas sent from the second oxidation treatment section 50 is increased compared to the temperature of the exhaust gas introduced into the second oxidation treatment section 50. The exhaust gas discharged from the second oxidation treatment section 50 passes through the supercharger bypass pipe 103 and merges with the exhaust pipe 102.

[0063] The exhaust gas is introduced into the first oxidation treatment section 40 through the exhaust pipe 102. The exhaust gas introduced into the first oxidation treatment section 40 is an exhaust gas in which the exhaust gas discharged from the supercharger 30 and the exhaust gas discharged from the second oxidation treatment section 50 merge and mix in the exhaust pipe 102. In addition, the exhaust gas discharged from the second oxidation treatment section 50 has a higher temperature than the exhaust gas discharged from the supercharger 30, so the exhaust gas discharged from the supercharger 30 and the exhaust gas discharged from the second oxidation treatment section 50 are mixed. The exhaust gas has a higher temperature than the exhaust gas discharged from the supercharger 30. Therefore, compared with the case where the supercharger bypass pipe 103 and the second oxidation treatment section 50 are not provided, the temperature of the exhaust gas introduced into the first oxidation treatment section 40 can be increased.

[0064] Furthermore, as the temperature of the introduced exhaust gas increases, the oxidation rate of methane in the first methane oxidation catalyst 42 increases, and thus methane can be efficiently oxidized by the first oxidation treatment unit 40 .

[0065] In addition, the second oxidation treatment unit 50 is provided in the middle of the supercharger bypass pipe 103, and is not provided between the exhaust unit 22 and the supercharger 30. Therefore, the exhaust gas discharged from the exhaust unit 22 is directly sent to the supercharger 30. Therefore, the reduction in the driving efficiency of the supercharger 30 is suppressed.

[0066] As a result, it is possible to satisfactorily oxidize the unburned components of methane contained in the exhaust gas, and suppress a decrease in the driving efficiency of the supercharger 30 .

[0067] Furthermore, in the above-mentioned first embodiment, the valve 60A is further provided to open and close the flow path of the exhaust gas from the exhaust portion 22 to the supercharger bypass pipe 103 .

[0068] Thus, the supply of the exhaust gas from the exhaust section 22 to the second oxidation treatment section 50 can be intermittent by opening and closing the valve 60A. Therefore, when heavy oil is used as the fuel of the engine 20A and the oxidation treatment of the unburned components of methane in the second oxidation treatment section 50 is not required, the supply of the exhaust gas to the second oxidation treatment section 50 can be stopped.

[0069] In the above-mentioned first embodiment, methane and heavy oil can be used switchably as the fuel of the engine 20A.

[0070] Thus, when methane is used as the fuel, by opening the valve 60A, the unburned portion of methane contained in the exhaust gas can be oxidized in the second oxidation treatment section 50 and the first oxidation treatment section 40 in sequence.

[0071] In addition, when heavy oil containing no unburned components of methane in the exhaust gas is used as the fuel, the valve 60A can be closed, and the exhaust gas is not sent to the second oxidation treatment section 50, but only sent to the supercharger 30. Thus, the supercharger 30 can be driven efficiently. In addition, when heavy oil is used as the fuel, the sulfur component contained in the exhaust gas can be suppressed from reaching the second oxidation treatment section 50, and the influence on the second methane oxidation catalyst 52 can be suppressed.

[0072] In the first embodiment, the switch 110 can switch the destination of the exhaust gas discharged from the supercharger 30 between the exhaust pipe 102 and the first oxidation treatment unit bypass pipe 105 .

[0073] Thus, for example, when methane is used as fuel, the exhaust gas discharged from the supercharger 30 is introduced into the first oxidation treatment unit 40 via the exhaust pipe 102 by the switching unit 110, thereby, as described above, the unburned portion of methane contained in the exhaust gas can be oxidized by the first oxidation treatment unit 40.

[0074] On the other hand, when heavy oil containing no unburned components of methane in the exhaust gas is used as fuel, the exhaust gas discharged from the supercharger 30 is introduced into the first oxidation treatment section bypass pipe 105 through the switching section 110, thereby enabling the exhaust gas to be efficiently discharged through the first oxidation treatment section bypass pipe 105 without being introduced into the first oxidation treatment section 40.

[0075] Furthermore, in the first embodiment, the capacity of the supercharger 30 is set according to the flow rate of air to be supplied to the engine 20A. When methane is used as fuel, the remaining portion of the exhaust gas discharged from the exhaust portion 22 that is not supplied to the supercharger 30 is introduced into the supercharger bypass pipe 103. In addition, by making the pipe diameter (inner diameter) D2 of the supercharger bypass pipe 103 smaller than the pipe diameter (inner diameter) D1 of the exhaust pipe 102, it is possible to correspond to the flow rate of the exhaust gas introduced into the supercharger bypass pipe 103. Thus, while ensuring the capacity of the supercharger 30, the unburned components of methane contained in the exhaust gas can be efficiently oxidized.

[0076] In addition, in the above-mentioned first embodiment, the temperature of the exhaust gas introduced into the first oxidation treatment section 40 is lower than the temperature of the exhaust gas introduced into the second oxidation treatment section 50, and the efficiency of the oxidation treatment of the unburned portion of methane contained in the exhaust gas is higher in the second oxidation treatment section 50 than in the first oxidation treatment section 40. However, in the first embodiment, by making the concentration of the catalyst component of the second methane oxidation catalyst 52 higher than the concentration of the catalyst component of the first methane oxidation catalyst 42, the methane oxidation treatment efficiency can be further improved, and the total amount of active components of the first methane oxidation catalyst 42 and the second methane oxidation catalyst 52 can be reduced.

[0077] Furthermore, in the first embodiment described above, the first methane oxidation catalyst 42 and the second methane oxidation catalyst 52 contain the same active component. Thus, the first oxidation treatment unit 40 and the second oxidation treatment unit 50 can be efficiently manufactured.

[0078] (Modification of the first embodiment)

[0079] In the first embodiment, the engine system 10A is provided in the ship 1 as an example, but the engine system 10A is not limited to being provided in the ship 1. The engine system 10A can also be applied to engine systems used in various equipment on land, for example.

[0080] <Second Embodiment>

[0081] Next, a second embodiment of the engine system of the present disclosure will be described. The second embodiment differs from the first embodiment only in the configuration of a portion of the engine system, and thus the same components as those of the first embodiment are described with the same reference numerals, and duplicate descriptions are omitted.

[0082] (Structure of the engine system)

[0083] Figure 6 It is a diagram showing a configuration of an engine system according to a second embodiment of the present disclosure.

[0084] like Figure 6 As shown, the engine system 10B illustrated in the second embodiment includes an engine 20B, a supercharger 30 , a first oxidation treatment unit 40 , and a second oxidation treatment unit 50 .

[0085] The engine 20B exhausts exhaust gas generated by burning fuel. The engine 20B illustrated in the present embodiment uses only methane as fuel.

[0086] The supercharger 30 is connected to the end of the manifold 24 on the downstream side in the flow direction of the exhaust gas. A portion of the exhaust gas flowing through the manifold 24 is introduced into the supercharger 30. The supercharger 30 of the second embodiment uses a high-efficiency supercharger that is more efficient than a supercharger used in a general engine system that uses only methane as fuel, thereby causing the flow rate of the exhaust gas from the engine 20B to exceed the flow rate of the exhaust gas required by the supercharger 30, and similarly to the first embodiment, a surplus amount of the exhaust gas can be generated.

[0087] The exhaust pipe 102 allows exhaust gas discharged from the supercharger 30 to flow.

[0088] The exhaust gas is introduced into the first oxidation treatment section 40 through the exhaust pipe 102. The exhaust gas introduced into the first oxidation treatment section 40 is a mixture of the exhaust gas exhausted from the supercharger 30 and the exhaust gas exhausted from the second oxidation treatment section 50.

[0089] The second oxidation treatment unit 50 is provided in the middle of the supercharger bypass pipe 103. The supercharger bypass pipe 103 allows a part of the exhaust gas exhausted from the exhaust unit 22 to bypass the supercharger 30 and merge with the exhaust pipe 102.

[0090] The exhaust gas is introduced into the second oxidation treatment section 50 through the supercharger bypass pipe 103 .

[0091] A valve 60B is provided at an upstream portion 103 p of the supercharger bypass pipe 103 , which is located upstream of the second oxidation treatment unit 50 in the flow direction of the exhaust gas.

[0092] The engine system 10B in the second embodiment does not include the first oxidation treatment unit bypass pipe 105 and the switching unit 110 of the engine system 10A illustrated in the first embodiment.

[0093] In such an engine system 10B, part of the exhaust gas discharged from the exhaust section 22 of the engine 20B is introduced into the supercharger 30 from the manifold 24 of the exhaust section 22. The supercharger 30 is driven by the exhaust gas introduced into the supercharger 30, and air is supplied to the engine 20B.

[0094] The valve 60B is adjusted in opening according to the rotation speed of the engine 20B, the rotation speed of the supercharger 30, and the like. Specifically, when the flow rate of the exhaust gas from the engine 20B exceeds the flow rate of the exhaust gas required by the supercharger 30 and a surplus amount of the exhaust gas is generated, the valve 60B is opened at an opening corresponding to the surplus amount. The valve 60B can be always opened during the operation of the engine 20B, or the valve 60B can be set to a fully closed state when no surplus amount of the exhaust gas is generated. When the valve 60B is opened, the remaining part (surplus amount) of the exhaust gas discharged from the exhaust section 22 of the engine 20B flows from the manifold 24 into the supercharger bypass pipe 103. The exhaust gas flowing into the supercharger bypass pipe 103 is introduced into the second oxidation treatment section 50. In the second oxidation section 50, the second methane oxidation catalyst 52 oxidizes the unburned part of the methane contained in the introduced exhaust gas.

[0095] The exhaust gas that has passed through the supercharger 30 and the exhaust gas that has passed through the second oxidation treatment section 50 merge in the exhaust pipe 102. The exhaust gas that has passed through the second oxidation treatment section 50 is subjected to oxidation treatment, and its temperature rises compared to the exhaust gas introduced into the second oxidation treatment section 50. Therefore, the temperature of the mixed gas (exhaust gas) formed by the exhaust gas that has passed through the supercharger 30 and the exhaust gas that has passed through the second oxidation treatment section 50 is higher than the temperature of the exhaust gas that has passed through the supercharger 30. The exhaust gas with a raised temperature is introduced from the exhaust pipe 102 into the first oxidation treatment section 40. In the first oxidation section 40, the unburned portion of methane contained in the introduced exhaust gas is oxidized by the first methane oxidation catalyst 42. The exhaust gas that has passed through the first oxidation treatment section 40 is discharged from the ventilator 9 into the atmosphere through the exhaust pipe 43.

[0096] (Effect)

[0097] In the engine system 10B of the second embodiment, similarly to the first embodiment, it is possible to satisfactorily oxidize the unburned components of methane contained in the exhaust gas and suppress a decrease in the driving efficiency of the supercharger 30 .

[0098] (Other Implementations)

[0099] As mentioned above, although the embodiment of this disclosure is described in detail with reference to drawings, the specific structure is not limited to this embodiment, and design changes etc. which do not deviate from the gist of this disclosure are also included.

[0100] The configurations of the engine systems 10A and 10B shown in the above-described embodiments are merely examples, and the configurations of the various components can be modified as appropriate.

[0101] In addition, the use of the engine systems 10A and 10B is not limited at all, and they can be used for various uses.

[0102] <Notes>

[0103] The engine systems 10A, 10B and the ship 1 described in each embodiment can be understood, for example, as follows.

[0104] (1) An engine system 10A, 10B of a first embodiment includes: an engine 20A, 20B driven by methane as fuel; a supercharger 30 driven by exhaust gas discharged from an exhaust section 22 of the engine 20A, 20B to supply air to the engine 20A, 20B; an exhaust pipe 102 through which the exhaust gas discharged from the supercharger 30 flows; a first oxidation treatment section 40 into which the exhaust gas is introduced via the exhaust pipe 102 and in which a first methane oxidation catalyst 42 is accommodated; a supercharger bypass pipe 103 through which a portion of the exhaust gas discharged from the exhaust section 22 bypasses the supercharger 30 and merges with the exhaust pipe 102; and a second oxidation treatment section 50 provided in the middle of the supercharger bypass pipe 103 and in which a second methane oxidation catalyst 52 is accommodated.

[0105] In the engine system 10A, 10B, the exhaust gas discharged from the exhaust section 22 of the engine 20A, 20B is sent to the supercharger 30 and the supercharger bypass pipe 103. The supercharger 30 is driven by the exhaust gas to supply air to the engine 20A, 20B. The exhaust gas discharged from the supercharger 30 flows through the exhaust pipe 102. The exhaust gas discharged from the supercharger 30 to the exhaust pipe 102 is lowered in temperature by performing the operation for supplying air to the engine 20A, 20B.

[0106] The exhaust gas sent to the supercharger bypass pipe 103 is introduced into the second oxidation treatment section 50. The second oxidation treatment section 50 oxidizes the unburned components of methane contained in the introduced exhaust gas by the second methane oxidation catalyst 52. The temperature of the exhaust gas sent from the second oxidation treatment section 50 rises by oxidizing the unburned components of methane. The exhaust gas discharged from the second oxidation treatment section 50 passes through the supercharger bypass pipe 103 and merges with the exhaust pipe 102.

[0107] The exhaust gas mixed with the exhaust gas discharged from the supercharger 30 and the exhaust gas discharged from the second oxidation treatment section 50, which merge in the exhaust pipe 102, is introduced into the first oxidation treatment section 40 through the exhaust pipe 102. The temperature of the exhaust gas discharged from the second oxidation treatment section 50 is higher than the temperature of the exhaust gas discharged from the supercharger 30, so the temperature of the exhaust gas introduced into the first oxidation treatment section 40 becomes higher. The higher the temperature of the introduced exhaust gas, the higher the oxidation rate of methane in the first methane oxidation catalyst 42. Therefore, methane can be efficiently oxidized in the first oxidation treatment section 40.

[0108] In addition, the second oxidation treatment unit 50 is provided in the middle of the supercharger bypass pipe 103, and is not provided between the exhaust unit 22 and the supercharger 30. Therefore, the exhaust gas discharged from the exhaust unit 22 is directly sent to the supercharger 30. Therefore, the reduction in the driving efficiency of the supercharger 30 is suppressed.

[0109] As a result, it is possible to satisfactorily oxidize the unburned components of methane contained in the exhaust gas, and suppress a decrease in the driving efficiency of the supercharger 30 .

[0110] (2) The engine system 10A, 10B of the second embodiment is the engine system 10A, 10B of (1) and further includes valves 60A, 60B that open and close the flow path of the exhaust gas from the exhaust portion 22 to the supercharger bypass pipe 103 .

[0111] Thus, by opening and closing the valves 60A and 60B, the flow path of the exhaust gas from the exhaust section 22 to the supercharger bypass pipe 103 can be opened and closed, and the supply of the exhaust gas from the exhaust section 22 to the second oxidation treatment section 50 can be intermittent. Therefore, when the oxidation treatment of the unburned components of methane contained in the exhaust gas of the second oxidation treatment section 50 is not required, the supply of the exhaust gas to the second oxidation treatment section 50 can be stopped.

[0112] (3) The engine system 10A of the third embodiment is the engine system 10A of (2), wherein the engine 20A uses methane and heavy oil as fuel.

[0113] Thus, when methane is used as the fuel, by opening the valve 60A, the unburned portion of methane contained in the exhaust gas can be oxidized in the second oxidation treatment section 50 and the first oxidation treatment section 40 in sequence.

[0114] In addition, when heavy oil is used as fuel, the exhaust gas does not contain unburned components of methane. Therefore, by closing the valve 60A, the exhaust gas can be sent only to the supercharger 30 without being sent to the second oxidation treatment unit 50. As a result, the supercharger 30 can be driven efficiently. In addition, when heavy oil is used as fuel, the sulfur component contained in the exhaust gas can be suppressed from reaching the second oxidation treatment unit 50, and the adverse effect on the second methane oxidation catalyst 52 can be suppressed.

[0115] (4) A fourth embodiment of the engine system 10A is the engine system 10A of (3), and further comprises: a first oxidation treatment unit bypass pipe 105 for allowing the exhaust gas discharged from the supercharger 30 to bypass the first oxidation treatment unit 40; and a switching unit 110 for switching the introduction destination of the exhaust gas discharged from the supercharger 30 between the exhaust pipe 102 and the first oxidation treatment unit bypass pipe 105.

[0116] Thus, the introduction destination of the exhaust gas discharged from the supercharger 30 can be switched between the exhaust pipe 102 and the first oxidation treatment unit bypass pipe 105 by the switching unit 110 .

[0117] When methane is used as the fuel, the exhaust gas discharged from the supercharger 30 is introduced into the exhaust pipe 102 by the switching unit 110, and the unburned components of methane contained in the exhaust gas can be oxidized in sequence by the second oxidation treatment unit 50 and the first oxidation treatment unit 40.

[0118] In addition, when heavy oil is used as the fuel, the exhaust gas does not contain unburned components of methane. Therefore, by introducing the exhaust gas discharged from the supercharger 30 into the first oxidation treatment unit bypass pipe 105 using the switching unit 110, the exhaust gas can be efficiently discharged through the first oxidation treatment unit bypass pipe 105 without being transported to the first oxidation treatment unit 40.

[0119] (5) The engine system 10A or 10B according to the fifth aspect is the engine system 10A or 10B according to any one of (1) to (4), wherein a pipe diameter D2 of the supercharger bypass pipe 103 is smaller than a pipe diameter D1 of the discharge pipe 102 .

[0120] In such a structure, the capacity of the supercharger 30 is set according to the flow rate of air to be supplied to the engines 20A and 20B. In this case, the remaining part of the exhaust gas discharged from the exhaust unit 22 that is not supplied to the supercharger 30 is introduced into the supercharger bypass pipe 103. By making the pipe diameter D2 of the supercharger bypass pipe 103 smaller than the pipe diameter D1 of the exhaust pipe 102, it is possible to correspond to the flow rate of the exhaust gas introduced into the supercharger bypass pipe 103. In this way, the unburned component of methane contained in the exhaust gas can be efficiently oxidized while ensuring the capacity of the supercharger 30.

[0121] (6) The engine system 10A or 10B of the sixth aspect is the engine system 10A or 10B according to any one of (1) to (5), wherein the concentration of the catalyst component of the second methane oxidation catalyst 52 is higher than the concentration of the catalyst component of the first methane oxidation catalyst 42 .

[0122] In such a configuration, the temperature of the exhaust gas introduced into the first oxidation treatment section 40 is lower than the temperature of the exhaust gas introduced into the second oxidation treatment section 50. Thus, the efficiency of the oxidation treatment of the unburned portion of methane contained in the exhaust gas is higher in the second oxidation treatment section 50 than in the first oxidation treatment section 40. By making the concentration of the catalyst component of the second methane oxidation catalyst 52 higher than the concentration of the catalyst component of the first methane oxidation catalyst 42, the oxidation treatment efficiency of methane can be further improved, and the total amount of active components of the first methane oxidation catalyst 42 and the second methane oxidation catalyst 52 can be reduced.

[0123] (7) The engine system 10A or 10B according to the seventh aspect is the engine system 10A or 10B according to any one of (1) to (6), wherein the first methane oxidation catalyst 42 and the second methane oxidation catalyst 52 contain the same active component.

[0124] Thus, the first oxidation treatment unit 40 and the second oxidation treatment unit 50 can be efficiently manufactured.

[0125] (8) A ship 1 according to an eighth aspect includes any one of the engine systems 10A described in (1) to (7).

[0126] Thus, it is possible to provide the ship 1 including the engine system 10A capable of satisfactorily oxidizing the unburned components of methane contained in the exhaust gas and capable of suppressing a decrease in the driving efficiency of the turbocharger 30 .

[0127] Possibility of Industrial Application

[0128] According to the engine system and the ship of the present disclosure, it is possible to satisfactorily oxidize the unburned components of methane contained in the exhaust gas and suppress a decrease in the driving efficiency of the supercharger.

[0129] Description of Reference Numerals

[0130] 1 ... ship 2 ... hull 2b ... stern 2j ... upper engine room 2k ... engine room 3A, 3B ... side 4 ... bottom 5 ... upper deck 6 ... bottom deck 7 ... upper structure 8 ... deck 9 ... ventilator 10A, 10B ... engine system 20A, 20B ... engine 21 ... engine body 22 ... exhaust part 23 ... connecting pipe 24 ... manifold 30 ... turbocharger 40 ... first oxidation treatment part 41 ... casing 42 ... first methane oxidation catalyst 43 ... exhaust pipe 5 0…second oxidation treatment section 51…housing 52…second methane oxidation catalyst 60A, 60B…valve 102…exhaust pipe 103…supercharger bypass pipe 103a…first end 103b…second end 103c…intermediate position 103p…upstream portion 103q…downstream portion 105…first oxidation treatment section bypass pipe 110…switching portion 111…first switching valve 112…second switching valve D1, D2…piping diameter Da…fore and stern direction Dv…up and down direction.

Claims

1. An engine system comprising: An engine powered by methane; a supercharger driven by exhaust gas discharged from an exhaust portion of the engine to supply air to the engine; an exhaust pipe for the exhaust gas discharged from the supercharger to flow; a first oxidation treatment section into which the exhaust gas is introduced through the exhaust pipe and in which a first methane oxidation catalyst is housed; a supercharger bypass pipe for allowing a portion of the exhaust gas discharged from the exhaust portion to bypass the supercharger and merge with the exhaust pipe; and The second oxidation treatment section is provided in the middle of the supercharger bypass pipe and contains a second methane oxidation catalyst.

2. The engine system according to claim 1, wherein: The engine system further includes a valve that opens and closes a flow path of the exhaust gas from the exhaust portion to the supercharger bypass pipe.

3. The engine system according to claim 2, wherein: The engine switches between using methane and heavy oil as fuel.

4. The engine system according to claim 3, wherein: The engine system further comprises: A first oxidation treatment unit bypass pipe allows the exhaust gas discharged from the supercharger to bypass the first oxidation treatment unit; and The switching unit switches an introduction destination of the exhaust gas discharged from the supercharger between the exhaust pipe and the first oxidation treatment unit bypass pipe.

5. The engine system according to claim 1 or 2, wherein: The supercharger bypass pipe has a smaller pipe diameter than the discharge pipe.

6. The engine system according to claim 1 or 2, wherein: The concentration of the catalyst component of the second methane oxidation catalyst is higher than the concentration of the catalyst component of the first methane oxidation catalyst.

7. The engine system according to claim 1 or 2, wherein: The first methane oxidation catalyst and the second methane oxidation catalyst include the same active component.

8. A ship comprising the engine system according to claim 1 or 2.

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