Exhaust gas after-treatment system and ship with same

Abstract

The exhaust gas aftertreatment system includes: a multi-fuel engine configured to selectively use two or more different types of fuel; and a catalyst chamber disposed downstream of the multi-fuel engine and containing an upstream catalyst and a downstream catalyst located downstream of the upstream catalyst.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0098116, filed July 27, 2023; Korean Patent Application No. 10-2023-0142169, filed October 23, 2023; Korean Patent Application No. 10-2024-0052158, filed April 18, 2024; Korean Patent Application No. 10-2024-0052159, filed April 18, 2024; and Korean Patent Application No. 10-2024-0052160, filed April 18, 2024, the entire contents of which are incorporated herein by reference as a part of this specification. Technical Field

[0003] This invention relates to exhaust gas aftertreatment systems and ships including such systems. Background Technology

[0004] Ships include multi-fuel engines that use two or more different types of fuel (e.g., gaseous fuels (natural gas, methane, etc.) and liquid fuels (diesel fuel)).

[0005] Gaseous fuels contain methane, which has strong carbon-hydrogen bonds and exists in a relatively stable state. Therefore, when methane is not completely consumed in the engine and is emitted, it will not oxidize naturally under exhaust gas temperature conditions and is thus emitted directly into the atmosphere in an untreated state.

[0006] Meanwhile, methane (CH4) is a greenhouse gas with a stronger greenhouse effect than an equivalent amount of carbon dioxide (CO2). To address global warming, the amount of methane emitted from exhaust gases must be reduced. Recently, with international organizations such as the International Maritime Organization (IMO) and the European Union (EU) strengthening regulations on reducing greenhouse gas (GHG) emissions, GHG emission controls, such as those targeting carbon dioxide (CO2) and carbon taxes, have been discussed, and technologies that prevent methane emissions into the atmosphere are needed. In response to this need, various studies are currently underway on methods for effectively purifying exhaust gases from multi-fuel engines (a major cause of environmental pollution), particularly for effectively removing the large amounts of methane contained in exhaust gases.

[0007] To effectively remove methane, methane oxidation catalysts (MOCs) are used in marine exhaust aftertreatment systems. Methane oxidation catalysts achieve appropriate performance when their temperature is higher than the exhaust gas temperature. However, the performance of methane oxidation catalysts can be easily degraded by sulfides and hydrocarbons.

[0008] The matters described in the background section are provided to enhance understanding of the background of the invention, and may include related technologies that are not known to those skilled in the art. Summary of the Invention

[0009] Technical issues

[0010] The present invention was designed with the above considerations in mind, and the purpose of the present invention is to provide an exhaust gas aftertreatment system and a ship including the same, wherein the exhaust gas aftertreatment system can pre-reduce or remove sulfur compounds, hydrocarbons, etc. contained in the exhaust gas by a diesel oxidation catalyst before the exhaust gas comes into contact with the methane oxidation catalyst, thereby extending the service life of the methane oxidation catalyst.

[0011] Furthermore, the object of the present invention is to provide an exhaust gas aftertreatment system and a ship including the same, wherein in the exhaust gas aftertreatment system, an injector mechanism is configured to inject an oxidizable substance (diesel fuel, urea, etc.) into an upstream catalyst, thereby causing an increase in the temperature of the downstream catalyst and improving the methane reduction efficiency of the downstream catalyst.

[0012] Furthermore, the object of the present invention is to provide an exhaust gas aftertreatment system capable of improving the regeneration efficiency of catalysts used to remove harmful substances from exhaust gases, and a ship including the same.

[0013] The problems to be addressed in the implementation plan are not limited to those described herein, and the objectives or effects that can be understood from the means of addressing the problem or from the implementation plan described below are also considered to be included.

[0014] Technical solution

[0015] An exhaust gas aftertreatment system for achieving the above-mentioned objectives, according to an embodiment of the present invention, may include: a multi-fuel engine configured to selectively use two or more different types of fuel; and a catalytic converter disposed downstream of the multi-fuel engine, comprising an upstream catalyst and a downstream catalyst disposed downstream of the upstream catalyst. The upstream catalyst may be at least one or a combination of a diesel oxidation catalyst and a methane oxidation catalyst, and the downstream catalyst may be at least one or a combination of a methane oxidation catalyst and a diesel oxidation catalyst.

[0016] According to the implementation scheme, the content of the catalyst composition of the upstream catalyst can be relatively higher than the content of the catalyst composition of the downstream catalyst.

[0017] According to the implementation plan, the content of precious metals in the upstream catalyst can be relatively higher than the content of precious metals in the downstream catalyst.

[0018] The catalytic chamber can be located downstream of the turbocharger.

[0019] An exhaust gas aftertreatment system according to an embodiment of the present invention may further include an inlet-side exhaust gas line and an outlet-side exhaust gas line, the inlet-side exhaust gas line being connected from the multi-fuel engine to the inlet of the catalytic converter, and the outlet-side exhaust gas line being connected to the outlet of the catalytic converter. An exhaust gas aftertreatment system for a ship according to an embodiment of the present invention may further include an inlet-side valve disposed in the inlet-side exhaust gas line and an outlet-side valve disposed in the outlet-side exhaust gas line.

[0020] The exhaust aftertreatment system according to an embodiment of the present invention may further include a bypass line that branches off from the inlet-side exhaust line so that exhaust gas from the multi-fuel engine bypasses the catalytic converter, and the bypass line then merges with the outlet-side exhaust line.

[0021] The exhaust gas aftertreatment system according to an embodiment of the present invention may further include a bypass valve disposed in the bypass line.

[0022] The catalytic chamber can be located upstream of the turbocharger.

[0023] According to an embodiment of the present invention, the exhaust gas aftertreatment system may further include an inlet-side exhaust gas line and an outlet-side exhaust gas line, wherein the inlet-side exhaust gas line is connected from the multi-fuel engine to the inlet of the catalytic converter, and the outlet-side exhaust gas line is connected from the outlet of the catalytic converter to the inlet of the turbine of the turbocharger.

[0024] An exhaust gas aftertreatment system according to an embodiment of the present invention may include: a multi-fuel engine configured to selectively use two or more different types of fuel; a catalytic chamber disposed downstream of the multi-fuel engine and comprising an upstream catalyst and a downstream catalyst disposed downstream of the upstream catalyst; an injector mechanism configured to inject an oxidizable substance into the upstream catalyst upstream of the upstream catalyst; and a controller configured to control the injector mechanism.

[0025] The injector mechanism may be a diesel injector mechanism configured to inject diesel fuel into the upstream catalyst.

[0026] The diesel injector mechanism may include a diesel injector and a fuel pump unit, the diesel injector being configured to inject the diesel fuel into the upstream catalyst, and the fuel pump unit being configured to supply the diesel fuel to the diesel injector.

[0027] The controller can control the fuel pump unit to determine the amount of diesel fuel injected into the diesel injector based on the target temperature of the downstream catalyst.

[0028] The injector mechanism may be a urea injector mechanism configured to inject urea into the upstream catalyst.

[0029] The urea injector mechanism may include a urea injector and a urea metering unit, the urea injector being configured to inject the urea into the upstream catalyst, and the urea metering unit being fluidly connected to the urea injector via a urea pipeline.

[0030] The controller can control the urea metering unit to determine the amount of urea injected through the urea injector based on the target temperature of the downstream catalyst.

[0031] According to an embodiment of the present invention, the exhaust gas aftertreatment system may further include an inlet-side exhaust gas line and an outlet-side exhaust gas line, wherein the inlet-side exhaust gas line is connected from the multi-fuel engine to the inlet of the catalytic converter, and the outlet-side exhaust gas line is connected to the outlet of the catalytic converter.

[0032] The exhaust gas aftertreatment system according to an embodiment of the present invention may further include an inlet-side valve disposed in the inlet-side exhaust gas pipeline and an outlet-side valve disposed in the outlet-side exhaust gas pipeline.

[0033] The exhaust aftertreatment system according to an embodiment of the present invention may further include a bypass line that branches off from the inlet-side exhaust line so that exhaust gas from the multi-fuel engine bypasses the catalytic converter, and the bypass line then merges with the outlet-side exhaust line.

[0034] The exhaust gas aftertreatment system according to an embodiment of the present invention may further include a bypass valve disposed in the bypass line.

[0035] The controller can be configured to control the injector mechanism, the inlet-side valve, the outlet-side valve, and the bypass valve based on the temperature of the downstream catalyst and whether gas escape occurs.

[0036] An exhaust gas aftertreatment system according to an embodiment of the present invention may include: a multi-fuel engine configured to selectively use two or more different types of fuel; a catalyst chamber disposed downstream of the multi-fuel engine and comprising an upstream catalyst and a downstream catalyst located downstream of the upstream catalyst; and a regenerated gas supply device configured to supply regenerated gas to the inlet of the catalyst chamber.

[0037] The regenerated gas may include a reducing agent and an inert gas.

[0038] The regenerated gas supply device may include a reducing agent supply unit and an inert gas supply unit, wherein the reducing agent supply unit is configured to supply a reducing agent and the inert gas supply unit is configured to supply an inert gas.

[0039] The exhaust gas aftertreatment system according to an embodiment of the present invention may further include an inlet-side exhaust gas pipeline connected to the inlet of the catalytic chamber. The reducing agent supply unit may be fluidly connected to the inlet-side exhaust gas pipeline via a reducing agent supply pipeline, and the reducing agent supply source may be located upstream of the reducing agent supply unit.

[0040] The inert gas supply unit can be fluidly connected to the inlet-side exhaust gas pipeline via an inert gas supply pipeline, and the inert gas supply source can be located upstream of the inert gas supply unit.

[0041] The inert gas supply unit may further include a heater configured to heat the inert gas.

[0042] The reducing agent supply line and the inert gas supply line can be connected to the inlet of the regenerated gas supply line, and the outlet of the regenerated gas supply line can be fluidly connected to the portion of the inlet-side exhaust gas line adjacent to the catalytic chamber.

[0043] The exhaust gas aftertreatment system according to an embodiment of the present invention may further include a water injector mechanism configured to inject water into the downstream catalyst.

[0044] The water injector mechanism can be located in the internal space of the catalyst chamber, downstream of the downstream catalyst.

[0045] The water injector mechanism may include a water pipe disposed downstream of the downstream catalyst and a plurality of water injectors disposed from the water pipe toward the downstream catalyst.

[0046] Ships according to embodiments of the present invention may include an exhaust gas aftertreatment system according to the above embodiments.

[0047] Beneficial effects

[0048] According to the present invention, since the exhaust gas first reacts with the upstream catalyst, an exothermic reaction can occur at the upstream catalyst, and therefore the temperature of the internal space of the catalytic chamber may be relatively increased. Consequently, the temperature of the downstream catalyst may also increase, and thus, the downstream catalyst can more effectively remove methane contained in the exhaust gas (i.e., the reactivity of the downstream catalyst increases at high temperatures).

[0049] According to the present invention, the upstream catalyst can be configured to have a smaller size than the downstream catalyst. Therefore, when the performance of the upstream catalyst (which is initially in contact with the exhaust gas) deteriorates due to the removal of hydrocarbons, sulfur, etc., only the upstream catalyst can be easily replaced, and the replacement cost of the upstream catalyst may be relatively low.

[0050] According to the present invention, the content of the catalyst composition in the upstream catalyst can be relatively higher than that in the downstream catalyst, and therefore, an exothermic reaction can be induced in the upstream catalyst during the reaction of the exhaust gas with the upstream catalyst. Consequently, the temperature inside the catalytic chamber can be relatively increased, and because the temperature of the downstream catalyst is higher than that of the exhaust gas, the downstream catalyst can more effectively remove methane contained in the exhaust gas.

[0051] According to the present invention, the precious metal content of the upstream catalyst can be relatively higher than that of the downstream catalyst. Therefore, the performance of the upstream catalyst is not reduced or minimized due to hydrocarbon poisoning, sulfur poisoning, etc., and an exothermic reaction may occur in the upstream catalyst during the reaction of the exhaust gas with the upstream catalyst. Consequently, the temperature inside the catalyst chamber may be relatively higher, and because the temperature of the downstream catalyst is higher than that of the exhaust gas, the downstream catalyst can more effectively remove methane contained in the exhaust gas. For example, since the upstream catalyst in the catalyst chamber is composed of a diesel oxidation catalyst and the downstream catalyst is composed of a methane oxidation catalyst, sulfur oxides and hydrocarbons contained in the exhaust gas can be pre-removed before the exhaust gas comes into contact with the methane oxidation catalyst, thereby extending the service life of the methane oxidation catalyst.

[0052] According to the present invention, since the injector mechanism injects oxidizable substances (diesel, urea, etc.) into the upstream catalyst, the oxidizable substances can be oxidized by reacting with the upstream catalyst, and the temperature of the exhaust gas passing through the upstream catalyst can be increased due to the oxidation of the oxidizable substances. Therefore, it can induce an increase in temperature in the downstream catalyst and the internal space of the catalyst chamber, and significantly improve the methane reduction efficiency of the downstream catalyst.

[0053] According to the present invention, regeneration gas can be supplied to the inlet of the catalytic chamber through a regeneration gas supply device to improve the regeneration efficiency of the catalyst in the catalytic chamber.

[0054] According to the present invention, since water is directly injected into the downstream catalyst through the water injector mechanism, the adsorbates attached to the downstream catalyst can be easily removed, thereby achieving smooth regeneration of the downstream catalyst. Attached Figure Description

[0055] Figure 1 This is a schematic view showing the overall structure of an exhaust gas aftertreatment system according to an embodiment of the present invention.

[0056] Figure 2 This is a view showing the catalyst arrangement structure disposed in the internal space of the catalyst chamber of the exhaust gas aftertreatment system according to an embodiment of the present invention.

[0057] Figure 3 This is a view showing the arrangement of catalysts in the internal space of the catalyst chamber of an exhaust gas aftertreatment system according to another embodiment of the invention.

[0058] Figure 4 This is a view showing a diesel injector mechanism installed in the catalytic chamber of an exhaust aftertreatment system according to an embodiment of the present invention, and a water injector mechanism disposed in the catalytic chamber.

[0059] Figure 5 This is a view showing a diesel injector mechanism installed in the catalytic chamber of an exhaust gas aftertreatment system and a water injector mechanism disposed in the catalytic chamber, according to another embodiment of the present invention.

[0060] Figure 6 This is a view showing a diesel injector mechanism installed on the inlet side exhaust gas pipeline of an exhaust gas aftertreatment system according to an embodiment of the present invention, and a water injector mechanism disposed in the catalytic converter chamber.

[0061] Figure 7 This is a view showing a diesel injector mechanism installed on the inlet side exhaust gas line of an exhaust gas aftertreatment system and a water injector mechanism disposed in the catalytic converter chamber, according to another embodiment of the present invention.

[0062] Figure 8 This is a view showing a urea injector mechanism installed in the catalytic chamber of an exhaust gas aftertreatment system according to an embodiment of the present invention, and a water injector mechanism disposed in the catalytic chamber.

[0063] Figure 9 This is a view showing a urea injector mechanism installed in the catalytic chamber of an exhaust gas aftertreatment system and a water injector mechanism arranged in the catalytic chamber, according to another embodiment of the present invention.

[0064] Figure 10 This is a view showing a urea injector mechanism installed in the inlet-side exhaust gas pipeline of an exhaust gas aftertreatment system according to an embodiment of the present invention, and a water injector mechanism disposed in the catalytic chamber.

[0065] Figure 11 This is a view showing a urea injector mechanism installed on the inlet side exhaust gas pipeline of an exhaust gas aftertreatment system and a water injector mechanism disposed in the catalyst chamber, according to another embodiment of the present invention.

[0066] Figure 12This is a view showing a regenerated gas supply device connected to an exhaust gas aftertreatment system according to an embodiment of the present invention.

[0067] Figure 13 This is a schematic view showing the overall structure of an exhaust gas aftertreatment system according to another embodiment of the present invention. Detailed Implementation

[0068] Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that identical or similar components are indicated by the same reference numerals wherever possible, even if they are described in different drawings. In the following description of the invention, detailed descriptions of known functions and configurations incorporated herein will be omitted to avoid obscuring the subject matter of the invention.

[0069] In the description of embodiments of this disclosure, terms such as first, second, A, B, (a), and (b) may be used. These terms are used only to distinguish one component from another and do not limit the components to their nature, order, sequence, etc.

[0070] In embodiments of the invention, the singular may also include the plural unless otherwise specifically stated in the text, and when it is described as “A, B and / or C (or at least one of A, B and C)”, it may include one or more of all combinations that can be composed of A, B and C.

[0071] Furthermore, when a component is described as “connected,” “linked,” or “combined” to another component, it may include not only cases where the component is directly “connected,” “linked,” or “combined” to another component, but also cases where the component is “connected,” “linked,” or “combined” by another component between the component and the other component.

[0072] Furthermore, when described as being formed or arranged "above" or "below" each component, "above" or "below" includes not only the case where two components are in direct contact with each other, but also the case where one or more other components are formed or arranged between the two components. Additionally, when expressed as "above" or "below," it can include not only the upward direction based on a single component, but also the downward direction.

[0073] Unless otherwise defined, the terms used in this disclosure are to be understood to have meanings known to those skilled in the art. Generally, terms as defined in commonly used dictionaries should be interpreted as having the same meaning as in the context of the relevant art, and should not be interpreted as having ideal or exaggerated meanings unless they are explicitly defined in this application.

[0074] refer to Figure 1According to an embodiment of the present invention, the exhaust gas aftertreatment system may include a multi-fuel engine 1 and a catalytic chamber 11 disposed downstream of the multi-fuel engine 1.

[0075] The multi-fuel engine 1 can be configured to selectively use two or more different types of fuel, such as gaseous fuels (natural gas, methane, etc.) and liquid fuels (diesel). For example, the multi-fuel engine 1 can operate in at least one of a gaseous fuel operating mode (where only gaseous fuel is used for combustion), a liquid fuel operating mode (where only liquid fuel is used for combustion), and a mixed fuel operating mode (where a mixed fuel obtained by mixing gaseous fuel and liquid fuel is used for combustion).

[0076] The catalytic converter 11 may include a variety of catalysts disposed therein, and the various catalysts may be configured to remove various harmful substances contained in the exhaust gas discharged from the multi-fuel engine 1. The catalytic converter 11 may have an inlet 11a and an outlet 11b, through which exhaust gas is introduced and through the outlet 11b is discharged. The various catalysts may be disposed in the catalytic converter 11 and spaced apart within the internal space of the catalytic converter 11 along the direction of exhaust gas flow.

[0077] Figure 1 A low-pressure exhaust aftertreatment system is shown, wherein the catalytic converter 11 is located downstream of the turbocharger 4. That is, Figure 1 The exhaust aftertreatment system shown can be a low-pressure exhaust aftertreatment system, in which low-pressure exhaust gas discharged from turbocharger 4 is introduced into catalytic chamber 11.

[0078] refer to Figure 1 The inlet-side exhaust gas line 2 can be connected from the multi-fuel engine 1 to the inlet 11a of the catalytic converter 11, and the outlet-side exhaust gas line 3 can be connected to the outlet 11b of the catalytic converter 11. The exhaust gas discharged from the multi-fuel engine 1 and the turbocharger 4 can be introduced into the inlet 11a of the catalytic converter 11 through the inlet-side exhaust gas line 2. The harmful substances contained in the exhaust gas passing through the catalytic converter 11 can be removed by the various catalysts, and the exhaust gas with the harmful substances removed can be discharged to the outside from the outlet 11b of the catalytic converter 11 through the outlet-side exhaust gas line 3.

[0079] The turbocharger 4 can be installed in the inlet-side exhaust gas line 2, and the turbocharger 4 can include a turbine 4a that rotates by means of exhaust gas and a compressor 4b that compresses the intake gas. The turbine 4a of the turbocharger 4 can be installed in the inlet-side exhaust gas line 2. Therefore, the exhaust gas discharged from the multi-fuel engine 1 can be introduced into the inlet 11a of the catalytic converter 11 after passing through the turbine 4a of the turbocharger 4.

[0080] according to Figure 1The low-pressure exhaust aftertreatment system of the embodiment may further include a bypass line 12, which branches off from the bifurcation point 2a of the inlet-side exhaust line 2, allowing the exhaust gas from the multi-fuel engine 1 to bypass the catalytic converter 11, and the bypass line 12 is then connected to the connection point 3a of the outlet-side exhaust line 3. The bifurcation point 2a of the inlet-side exhaust line 2 may be located downstream of the turbine 4a of the turbocharger 4, and therefore, the inlet of the bypass line 12 may be connected to the inlet-side exhaust line 2 at a point downstream of the turbine 4a of the turbocharger 4.

[0081] refer to Figure 1 The inlet-side valve 13 can be installed in the inlet-side exhaust gas line 2, and the outlet-side valve 14 can be installed in the outlet-side exhaust gas line 3. The inlet-side valve 13 and / or the outlet-side valve 14 can be selectively opened and closed, and therefore, the exhaust gas can pass through or not pass through the catalytic chamber 11.

[0082] refer to Figure 1 Bypass valve 15 can be installed in bypass line 12, and similarly, since bypass valve 15 selectively opens and closes, exhaust gas can pass through or not pass through bypass valve 15.

[0083] For initial performance verification, methane meters can be selectively installed, and methane meters 16 and 17 can be removed after performance verification is completed. For example, as Figure 1 As shown, the inlet-side methane meter 16 can be detachably installed in the inlet-side exhaust gas line 2, and the inlet-side methane meter 16 can measure the methane concentration in the exhaust gas introduced into the catalytic chamber 11 through the inlet 11a. The outlet-side methane meter 17 can be detachably installed in the outlet-side exhaust gas line 3, and the outlet-side methane meter 17 can measure the methane concentration in the exhaust gas discharged from the catalytic chamber 11 through the outlet 11b.

[0084] refer to Figure 1 An inlet-side temperature sensor T1 can be located in the portion of the catalyst chamber 11 adjacent to the inlet 11a, and can be configured to measure the temperature upstream of the catalyst in the catalyst chamber 11. An outlet-side temperature sensor T2 can be located in the portion of the catalyst chamber 11 adjacent to the outlet 11b, and can be configured to measure the temperature downstream of the catalyst in the catalyst chamber 11. An intermediate temperature sensor T3 can be located in the middle of the catalyst chamber 11 and can be configured to measure the temperature of the space between the chambers within the catalyst chamber 11. A differential pressure gauge PDT can be installed in the catalyst chamber 11, and can be configured to measure the pressure difference between the inlet-side pressure and the outlet-side pressure of the catalyst chamber 11.

[0085] The controller 20 can control the operation of the inlet valve 13, outlet valve 14, bypass valve 15, etc., based on the methane concentration in the exhaust gas measured by the inlet-side methane meter 16, the methane concentration in the exhaust gas measured by the outlet-side methane dosimeter 17, the temperature measured by the inlet-side temperature sensor T1, the temperature measured by the outlet-side temperature sensor T2, the temperature measured by the intermediate temperature sensor T3, the pressure measured by the differential pressure gauge PDT, etc.

[0086] Figure 2 This is a view illustrating an example of a catalyst arrangement structure disposed within the internal space of the catalytic chamber 11 of an exhaust gas aftertreatment system according to an embodiment of the present invention. (Reference) Figure 2 The catalyst chamber 11 may include an upstream catalyst 21 disposed adjacent to the inlet of the catalyst chamber 11 and a downstream catalyst 31 disposed adjacent to the outlet of the catalyst chamber 11. The upstream catalyst 21 and the downstream catalyst 31 may be oxidation catalysts. The upstream catalyst 21 may be at least one or a combination of diesel oxidation catalyst and methane oxidation catalyst, and the downstream catalyst 31 may be at least one or a combination of methane oxidation catalyst and diesel oxidation catalyst.

[0087] according to Figure 2 In one implementation scheme, the upstream catalyst 21 may be a diesel oxidation catalyst (DOC) configured to adsorb sulfur components in the exhaust gas to reduce the sulfur components in the exhaust gas discharged from the upstream catalyst 21.

[0088] according to Figure 2 In one embodiment, the downstream catalyst 31 may be a methane oxidation catalyst configured to remove methane produced by the incomplete combustion of gaseous fuel.

[0089] According to the implementation scheme, the content of the catalyst composition in the upstream catalyst 21 can be relatively less than the content of the catalyst composition in the downstream catalyst 31, and the upstream catalyst 21 can be configured to have a relatively smaller size than the downstream catalyst 31. Therefore, when the performance of the upstream catalyst 21, which is initially in contact with the exhaust gas, deteriorates due to the reduction or removal of hydrocarbons, sulfur, etc., only the upstream catalyst 21 can be easily replaced, and the replacement cost of the upstream catalyst 21 can be relatively reduced. The replacement cycle of the upstream catalyst 21 can be appropriately determined by various methods that can directly or indirectly confirm the performance of the upstream catalyst 21 (e.g., counting methods of drive time, methane oxidation reduction performance, and temperature rise).

[0090] According to another embodiment, the content of the catalyst composition in the upstream catalyst 21 can be relatively higher than that in the downstream catalyst 31, and therefore, an exothermic reaction can be initiated in the upstream catalyst 21 during the reaction of the exhaust gas with the upstream catalyst 21. Consequently, due to the exothermic reaction of the upstream catalyst 21, the temperature of the exhaust gas passing through the upstream catalyst 21 can be relatively increased. Therefore, the temperature of the downstream catalyst 31 can rise to the reaction temperature due to the exhaust gas discharged from the upstream catalyst 21, and thus, the downstream catalyst 31 can more effectively remove methane contained in the exhaust gas.

[0091] According to another embodiment, the precious metal content of the upstream catalyst 21 can be relatively higher than that of the downstream catalyst 31. Therefore, the performance of the upstream catalyst 21 is not reduced or minimized due to hydrocarbon poisoning, sulfur poisoning, etc., and an exothermic reaction can be initiated in the upstream catalyst 21 during the reaction of the exhaust gas with the upstream catalyst 21. Therefore, due to the exothermic reaction of the upstream catalyst 21, the temperature of the exhaust gas passing through the upstream catalyst 21 can be relatively increased. Consequently, the temperature of the downstream catalyst 31 can be raised to the required reaction temperature due to the exhaust gas discharged from the upstream catalyst 21, and thus, the downstream catalyst 31 can more effectively remove methane contained in the exhaust gas.

[0092] Figure 3 This is a view illustrating an example of a catalyst arrangement structure disposed within the internal space of the catalytic chamber 11 of an exhaust gas aftertreatment system according to another embodiment of the invention. (See reference) Figure 3 The catalyst chamber 11 may include an upstream catalyst 21 disposed adjacent to the inlet of the catalyst chamber 11 and a plurality of downstream catalysts 31 and 32 disposed downstream of the upstream catalyst 21. The plurality of downstream catalysts 31 and 32 may include a first downstream catalyst 31 disposed downstream of the upstream catalyst 21 and a second downstream catalyst 32 disposed downstream of the first downstream catalyst 31. The second downstream catalyst 32 may be disposed adjacent to the outlet 11b of the catalyst chamber 11. The upstream catalyst 21 and the downstream catalysts 31 and 32 may be oxidation catalysts. The upstream catalyst 21 may be at least one or a combination of a diesel oxidation catalyst and a methane oxidation catalyst, and the downstream catalysts 31 and 32 may be at least one or a combination of a methane oxidation catalyst and a diesel oxidation catalyst.

[0093] according to Figure 3 In one implementation scheme, the upstream catalyst 21 may be a diesel oxidation catalyst (DOC) configured to adsorb sulfur components in the exhaust gas to reduce the sulfur components in the exhaust gas discharged from the upstream catalyst 21.

[0094] according to Figure 3In one embodiment, the first downstream catalyst 31 and the second downstream catalyst 32 may be methane oxidation catalysts configured to remove methane produced due to incomplete combustion of gaseous fuel.

[0095] According to the implementation scheme, the amount of catalyst composition in the first downstream catalyst 31 can be equal to the amount of catalyst composition in the second downstream catalyst 32. Furthermore, the amount of catalyst composition in the upstream catalyst 21 can be relatively smaller than the amount of catalyst composition in each of the downstream catalysts 31 and 32, and the upstream catalyst 21 can be configured to have a relatively smaller size than each of the downstream catalysts 31 and 32. Therefore, when the performance of the upstream catalyst 21 deteriorates due to the removal of hydrocarbons, sulfur, etc., only the upstream catalyst 21 can be easily replaced, and the replacement cost of the upstream catalyst 21 can be relatively low.

[0096] According to another embodiment, the content of the catalyst composition in the upstream catalyst 21 can be relatively higher than the content of the catalyst composition in each of the downstream catalysts 31 and 32. Therefore, during the reaction of the exhaust gas with the upstream catalyst 21, an exothermic reaction may be initiated in the upstream catalyst 21. Consequently, due to the exothermic reaction of the upstream catalyst 21, the temperature of the exhaust gas passing through the upstream catalyst 21 can be relatively increased. Therefore, the temperature of the downstream catalyst 31 can be raised to the desired reaction temperature by means of the exhaust gas discharged from the upstream catalyst 21, and thus, each of the downstream catalysts 31 and 32 can more effectively remove methane contained in the exhaust gas.

[0097] According to another embodiment, the precious metal content of the upstream catalyst 21 can be relatively higher than that of each of the downstream catalysts 31 and 32. Therefore, the performance of the upstream catalyst 21 can be maintained without being reduced or minimized due to hydrocarbon poisoning, sulfur poisoning, etc., and an exothermic reaction can be initiated in the upstream catalyst 21 during the reaction of the exhaust gas with the upstream catalyst 21. Consequently, due to the exothermic reaction of the upstream catalyst 21, the temperature of the exhaust gas passing through the upstream catalyst 21 can be relatively increased. Therefore, the temperature of the downstream catalyst 31 can be raised to the required reaction temperature by means of the exhaust gas discharged from the upstream catalyst 21, and thus, each of the downstream catalysts 31 and 32 can more effectively remove methane contained in the exhaust gas.

[0098] The inlet-side temperature sensor T1 measures the upstream temperature of the upstream catalyst 21, the outlet-side temperature sensor T2 measures the downstream temperature of each of the downstream catalysts 31 and 32, and the intermediate-side temperature sensor T3 measures the temperature of the space between the upstream catalyst 21 and each of the downstream catalysts 31 and 32. Because the intermediate-side temperature sensor T3 measures the temperature of the space between the upstream catalyst 21 and each of the downstream catalysts 31 and 32, it can effectively detect the increase in exhaust gas temperature caused by the upstream catalyst 21.

[0099] As described above, since the upstream catalyst 21 is located upstream of the downstream catalyst 22, the upstream catalyst 21 (rather than the downstream catalyst 22) can contact and react with the exhaust gas. Therefore, the exhaust gas, which has previously had hydrocarbons (HC) and sulfur reduced or removed by the upstream catalyst 21, can contact and react with the downstream catalysts 31 and 32. Consequently, the methane contained in the exhaust gas can be effectively removed or reduced by the downstream catalysts 31 and 32 (which are methane oxidation catalysts), and the service life of the downstream catalysts 31 and 32 can be extended.

[0100] Furthermore, since the exhaust gas first reacts with the upstream catalyst 21, an exothermic reaction can occur in the upstream catalyst 21. Therefore, due to the exothermic reaction of the upstream catalyst 21, the temperature of the exhaust gas passing through the upstream catalyst 21 can be relatively increased. Consequently, the temperature of the downstream catalyst 31 can be raised to the desired reaction temperature by means of the exhaust gas discharged from the upstream catalyst 21, and thus, each of the downstream catalysts 31 and 32 can more effectively remove methane contained in the exhaust gas.

[0101] The exhaust gas aftertreatment system 10 for ships according to an embodiment of the present invention may further include an injector mechanism configured to inject an oxidizable substance into the upstream catalyst 21 at a location upstream of the upstream catalyst 21. According to the embodiment, the oxidizable substance may be at least one of diesel fuel, LNG, methanol, ethanol, or urea, or a combination of two or more of these fuels. Since the oxidizable substance is oxidized by reacting with the upstream catalyst 21, the temperature of the exhaust gas passing through the upstream catalyst 21 can be relatively increased due to the oxidation reaction of the oxidizable substance, and each of the downstream catalysts 31 and 32 can be raised to the desired reaction temperature by means of the exhaust gas discharged from the upstream catalyst 21. That is, the temperature of each of the downstream catalysts 31 and 32 can be increased by means of the exhaust gas whose temperature is increased by the upstream catalyst 21, and therefore, the methane reduction efficiency of the downstream catalysts 31 and 32 can be significantly improved. The injector mechanism may be located upstream of the upstream catalyst 21. For example, the injector mechanism may be located at a portion of the catalytic chamber 11 adjacent to the inlet 11a of the catalytic chamber 11 or at a portion of the inlet-side exhaust gas line 2 adjacent to the catalytic chamber 11. The controller 20 can be configured to control the injector mechanism, upstream valve 13, downstream valve 14 and bypass valve 15 based on the temperature of each of the downstream catalysts 31 and 32 and whether gas escape occurs in the multi-fuel engine.

[0102] according to Figures 4 to 7 In one implementation scheme, the injector mechanism can be a diesel injector mechanism 40 that injects diesel fuel into the upstream catalyst 21.

[0103] refer to Figures 4 to 7 The diesel fuel injector mechanism 40 may include a diesel fuel injector 41 for injecting diesel fuel into the upstream catalyst 21, a diesel fuel tank 43 fluidly connected to the diesel fuel injector 41 via a diesel fuel line 42, a fuel pump unit 44 configured to supply diesel fuel to the diesel fuel injector 41, and a fuel metering unit 45 configured to regulate the flow rate of the diesel fuel. The fuel pump unit 44 may consist of a fuel pump and its peripheral devices, and the fuel metering unit 45 may consist of a fuel flow meter, a fuel flow regulating valve, and its peripheral devices.

[0104] refer to Figure 4 and Figure 5 The diesel injector 41 can be installed in the catalytic chamber 11 adjacent to the inlet 11a of the catalytic chamber 11.

[0105] refer to Figure 6 and Figure 7 The diesel injector 41 can be installed in the inlet-side exhaust gas line 2.

[0106] Since the diesel fuel injector 41 injects diesel fuel into the upstream catalyst 21, the diesel fuel can be oxidized, and due to the oxidation reaction of the diesel fuel, the temperature of the exhaust gas passing through the upstream catalyst 21 can be relatively increased. Therefore, due to the exhaust gas discharged from the upstream catalyst 21, the temperature of the downstream catalyst 31 can be raised to the reaction temperature. According to an embodiment, the controller 20 can control the fuel pump unit 44 to determine the amount of diesel fuel injected by the diesel fuel injector 41 based on the target temperature (e.g., about 300°C to about 500°C) of the downstream catalysts 31 and 32 that optimizes the methane removal efficiency.

[0107] According to another embodiment, the controller 20 can determine whether the temperature of the downstream catalysts 31 and 32 exceeds the allowable temperature based on: the upstream temperature of the upstream catalyst 21 measured by the inlet-side temperature sensor T1, the downstream temperature of each of the downstream catalysts 31 and 32 measured by the outlet-side temperature sensor T2, and the temperature of the space between the upstream catalyst 21 and each of the downstream catalysts 31 and 32 measured by the intermediate-side temperature sensor T3. When the temperature of each of the downstream catalysts 31 and 32 exceeds the allowable temperature, the controller 20 can control the fuel pump unit 44 to reduce the amount of diesel fuel injected, adjust the opening degree of the bypass valve 15 to allow a portion of the exhaust gas to pass through the bypass line 12, and close the upstream side valve 13 and the downstream side valve 14 to prevent exhaust gas from passing through the catalytic converter 11. According to another embodiment, when a gas trip occurs in the multi-fuel engine 1, the controller 20 can stop the fuel pump unit 44 to stop the injection of diesel fuel, close the upstream valve 13 and the downstream valve 14 to prevent exhaust gas from passing through the catalytic converter 11, and fully open the bypass valve 15 to allow exhaust gas to pass through the bypass line 12. When the gaseous fuel operating mode of the multi-fuel engine 1 malfunctions, misfire may occur in the combustion chamber at a level equal to or higher than a certain threshold. In this situation, the multi-fuel engine 1 switches to liquid fuel operating mode, and this condition can be referred to as "gas cutoff". In such a gas escape event, the controller 20 can stop the fuel pump unit 44 to stop the injection of diesel fuel. In addition, the controller 20 can fully open the bypass valve 15 and close the upstream valve 13 and the downstream valve 14, so that the exhaust gas passes only through the bypass line 12 and bypasses the catalytic converter 11.

[0108] according to Figures 8 to 11 In one embodiment, the injector mechanism may be a urea injector mechanism 50, which is configured to inject urea into the upstream catalyst 21 upstream of the upstream catalyst 21.

[0109] refer to Figures 8 to 11The urea injector mechanism 50 may include a urea injector 51 for injecting urea into the upstream catalyst 21 and a urea metering unit 53 fluidly connected to the urea injector 51 via a urea line 52. Since the urea metering unit 53 is connected to the urea supply system of the SCR catalytic mechanism, the urea metering unit 53 can utilize the urea supply system of the SCR catalytic mechanism.

[0110] refer to Figure 8 and Figure 9 The urea injector 51 can be installed in the catalyst chamber 11 adjacent to the inlet 11a of the catalyst chamber 11.

[0111] refer to Figure 10 and Figure 11 The urea injector 51 can be installed in the portion of the inlet-side exhaust gas line 2 adjacent to the catalytic chamber 11.

[0112] When urea is injected into the upstream catalyst 21 through the urea injector 51, the urea can be oxidized, and due to the oxidation reaction of urea, the temperature of the exhaust gas passing through the upstream catalyst 21 can relatively increase. Therefore, since the temperature of the downstream catalyst 31 rises to the reaction temperature due to the exhaust gas discharged from the upstream catalyst 21, it can trigger a temperature increase in each of the downstream catalysts 31 and 32.

[0113] According to the implementation scheme, the controller 20 can control the urea metering unit 53 such that the amount of urea injected through the urea injector 51 is determined based on the target temperature (e.g., about 300°C to about 500°C) of the downstream catalysts 31 and 32 that can optimize the methane removal efficiency.

[0114] According to another embodiment, the controller 20 can determine whether the temperature of the downstream catalysts 31 and 32 exceeds the allowable temperature based on: the upstream temperature of the upstream catalyst 21 measured by the inlet-side temperature sensor T1, the downstream temperature of each of the downstream catalysts 31 and 32 measured by the outlet-side temperature sensor T2, and the temperature of the space between the upstream catalyst 21 and each of the downstream catalysts 31 and 32 measured by the intermediate-side temperature sensor T3. When the temperature of each of the downstream catalysts 31 and 32 exceeds the allowable temperature, the controller 20 can control the urea metering unit 53 to reduce the amount of urea injected, adjust the opening degree of the bypass valve 15 to allow a portion of the exhaust gas to pass through the bypass pipeline 12, and close the upstream side valve 13 and the downstream side valve 14 to block the passage of exhaust gas through the catalytic chamber 11.

[0115] According to another embodiment, when a gas supply interruption occurs in the multi-fuel engine 1, the controller 20 can stop the urea metering unit 53 to stop urea injection, close the upstream valve 13 and the downstream valve 14 to block the passage of exhaust gas through the catalytic converter 11, and fully open the bypass valve 15 to allow exhaust gas to pass through the bypass line 12. When the gaseous fuel operating mode of the multi-fuel engine 1 is abnormal, ignition failure may occur in the combustion chamber at a level equal to or higher than a certain threshold. In this case, the multi-fuel engine 1 switches to a liquid fuel operating mode, and this situation can be referred to as a "gas supply interruption". In such a gas escape event, the controller 20 can stop the urea metering unit 53 to stop urea fuel injection. In addition, the controller 20 can fully open the bypass valve 15 and close the upstream valve 13 and the downstream valve 14, so that exhaust gas passes only through the bypass line 12 and not through the catalytic converter 11.

[0116] according to Figures 4 to 11 In this embodiment, the upstream catalyst 21, serving as a diesel oxidation catalyst, can have a relatively lower content of precious metals than each of the downstream catalysts 31 and 32, serving as methane oxidation catalysts. Therefore, the upstream catalyst 21 can be relatively cheaper than the downstream catalysts 31 and 32. Consequently, hydrocarbons (HC), sulfur (S), and other catalyst-poisoning components can be reduced or removed from the upstream catalyst 21 (which serves as the diesel oxidation catalyst), and thus the service life of the downstream catalysts 31 and 32, serving as the methane oxidation catalysts, can be extended.

[0117] An exhaust gas aftertreatment system according to an embodiment of the present invention may include a water injector mechanism 60 configured to regenerate upstream catalyst 21 and downstream catalysts 31 and 32 by injecting water into them. The water injector mechanism 60 can directly inject water into upstream catalyst 21 and downstream catalysts 31 and 32 to wash adsorbates adsorbed on them, thereby smoothly regenerating upstream catalyst 21 and downstream catalysts 31 and 32.

[0118] refer to Figures 4 to 11A water injector mechanism 60 can be disposed within the internal space of the catalyst chamber 11 downstream of the upstream catalyst 21 and downstream of each of the downstream catalysts 31 and 32. The water injector mechanism 60 may include a water pipe 61 extending downstream of the upstream catalyst 21 and downstream of each of the downstream catalysts 31 and 32, and a plurality of water injectors 62 arranged from the water pipe 61 toward each of the upstream catalyst 21 and the downstream catalysts 31 and 32. A water supply source can be connected to the water pipe 61 via a water supply line, and a water pump can be disposed in the water supply line to supply water to the water pipe 61. Each of the water injectors 62 can directly inject water into each of the upstream catalyst 21 and the downstream catalysts 31 and 32 to remove adsorbates adsorbed on the upstream catalyst 21 and the downstream catalysts 31 and 32, thereby improving the regeneration efficiency of the upstream catalyst 21 and the downstream catalysts 31 and 32.

[0119] refer to Figure 1 According to an embodiment of the present invention, the exhaust gas aftertreatment system may further include a regenerated gas supply device 70, which is configured to supply regenerated gas to the inlet 11a of the catalytic chamber 11.

[0120] According to the implementation scheme, the regeneration gas may include a reducing agent for reducing catalysts 21, 31, and 32 and an inert gas for creating a reducing atmosphere in the internal space of the catalyst chamber 11. According to a specific implementation scheme, the reducing agent may be CH4, H2, etc., and the inert gas may be N2, serving as a balancing gas for forming the reducing atmosphere.

[0121] refer to Figure 12 The regenerated gas supply device 70 may include a reducing agent supply unit 71 for supplying reducing agent and an inert gas supply unit 74 for supplying inert gas.

[0122] The reducing agent supply unit 71 can be configured to supply a reducing agent to the interior space of the catalyst chamber 11 for reducing oxidized substances adsorbed on the surfaces of catalysts 21, 31, and 32. According to a specific embodiment, the reducing agent supply unit 71 can be fluidly connected to the inlet-side exhaust gas line 2 via a reducing agent supply line 72. A reducing agent supply source 73 can be located upstream of the reducing agent supply unit 71, and the reducing agent supply unit 71 can be configured to supply reducing agent from the reducing agent supply source 73 to the inlet-side exhaust gas line 2.

[0123] The inert gas supply unit 74 can be configured to supply inert gas to the interior space of the catalytic chamber 11, thereby creating an oxygen-free reducing atmosphere within the catalytic chamber 11. According to a specific embodiment, the inert gas supply unit 74 can be fluidly connected to the inlet-side exhaust gas line 2 via an inert gas supply line 75. An inert gas supply source 77 can be located upstream of the inert gas supply unit 74, and the inert gas supply unit 74 can be configured to supply inert gas from the inert gas supply source 77 to the inlet-side exhaust gas line 2.

[0124] According to the implementation scheme, the inert gas supply unit 74 may further include a heater 76, which is configured to heat the inert gas to a set temperature. The heater 76 may be located downstream of the inert gas supply unit 74, and the high-temperature inert gas heated by the heater 76 may be supplied to the interior space of the catalytic chamber 11 through the inlet-side exhaust gas line 2.

[0125] The reducing agent supply line 72 and the inert gas supply line 75 can converge at the inlet of the regeneration gas supply line 78, and the outlet of the regeneration gas supply line 78 can be fluidly connected to a portion of the inlet-side exhaust gas line 2 adjacent to the catalyst chamber 11. The reducing agent supplied by the reducing agent supply line 72 and the inert gas supplied by the inert gas supply line 75 can be supplied to the inlet-side exhaust gas line 2 through the regeneration gas supply line 78. The reducing agent and the inert gas can be supplied to the inlet 11a of the catalyst chamber 11 through the inlet-side exhaust gas line 2. Therefore, the internal space of the catalyst chamber 11 can be made to achieve a reducing atmosphere by means of the reducing agent and the high-temperature inert gas, and the oxidants poisoned on the surface of each of the catalysts 21, 31 and 32 can be reduced by means of the reducing agent, and thus each of the catalysts 21, 31 and 32 can be effectively regenerated by means of the reducing agent and the inert gas.

[0126] according to Figures 2 to 11 The catalytic arrangement structure of the catalytic chamber 11, the diesel injector mechanism, the urea injector mechanism, the water injector mechanism, and the regeneration gas supply device in the embodiment may not be limited to... Figure 1 It is not limited to low-pressure exhaust gas after-treatment systems, but can also be applied to the same applications. Figure 13 High-pressure exhaust gas after-treatment system.

[0127] Figure 13 A high-pressure exhaust aftertreatment system is shown, wherein the catalytic converter 11 is located upstream of the turbocharger 4. That is, Figure 13 The exhaust aftertreatment system shown can be a high-pressure exhaust aftertreatment system, wherein the high-pressure exhaust gas discharged from the multi-fuel engine 1 passes through the catalytic converter 11 or bypass line 12 before being introduced into the turbine 4a of the turbocharger 4.

[0128] refer to Figure 13The exhaust gas storage device 1a can be located downstream of the multi-fuel engine 1, and the exhaust gas storage device 1a can contain the exhaust gas discharged from the multi-fuel engine 1.

[0129] refer to Figure 13 The inlet-side exhaust gas line 2 can be connected from the exhaust gas reservoir 1a to the inlet 11a of the catalytic converter 11, and the outlet-side exhaust gas line 3 can be connected from the outlet 11b of the catalytic converter 11 to the inlet of the turbine 4a of the turbocharger 4. Exhaust gas from the multi-fuel engine 1 can be introduced into the inlet 11a of the catalytic converter 11 through the exhaust gas reservoir 1a and the inlet-side exhaust gas line 2. The multiple catalysts remove harmful substances from the exhaust gas passing through the catalytic converter 11, and the exhaust gas, after the harmful substances have been removed, can be discharged to the outside from the outlet 11b of the catalytic converter 11 via the outlet-side exhaust gas line 3 and the turbine 4a of the turbocharger 4.

[0130] according to Figure 13 The high-pressure exhaust gas aftertreatment system of the implementation scheme may further include a bypass line 12, which branches off from the inlet-side exhaust gas line 2 or the exhaust gas reservoir 1a to allow the exhaust gas to bypass the catalyst chamber 11, and the bypass line 12 is then connected to the outlet-side exhaust gas line 3.

[0131] refer to Figure 13 An inlet-side valve 13 may be installed in the inlet-side exhaust gas pipeline 2, and an outlet-side valve 14 may be installed in the outlet-side exhaust gas pipeline 3. The inlet-side valve 13 and / or the outlet-side valve 14 can be selectively opened and closed, and therefore, the exhaust gas may or may not pass through the catalytic chamber 11.

[0132] refer to Figure 13 Bypass valve 15 can be installed in bypass line 12, and similarly, since bypass valve 15 selectively opens and closes, exhaust gas can pass through or not pass through bypass valve 15.

[0133] For initial performance verification, a methane meter can be selectively installed, and can be removed after performance verification. According to the implementation scheme, only the outlet-side methane meter 17 can be installed in the outlet-side exhaust gas line 3. For example, a detector can be installed on one side of the outlet-side exhaust gas line 3, and the outlet-side methane meter 17 can be detachably installed to the detector. Furthermore, the methane meter can confirm the upstream and downstream measurement levels of methane in the exhaust gas passing through the catalytic chamber 11 according to the time difference through the operation of the inlet-side valve 13, the outlet-side valve 14, and the bypass valve 15. According to another example, the inlet-side methane meter 16 can be installed in the inlet-side exhaust gas line 2, and the inlet-side methane meter 16 can measure the methane concentration in the exhaust gas introduced into the catalytic chamber 11 through the inlet 11a. The outlet-side methane meter 17 can be installed in the outlet-side exhaust gas line 3, and the outlet-side methane meter 17 can measure the methane concentration in the exhaust gas discharged from the outlet 11b of the catalytic chamber 11.

[0134] refer to Figure 13 An inlet-side temperature sensor T1 can be located in the portion of the catalyst chamber 11 adjacent to the inlet 11a, and can be configured to measure the temperature upstream of the catalyst in the catalyst chamber 11. An outlet-side temperature sensor T2 can be located in the portion of the catalyst chamber 11 adjacent to the outlet 11b, and can be configured to measure the temperature downstream of the catalyst in the catalyst chamber 11. An intermediate temperature sensor T3 can be located in the middle of the catalyst chamber 11 and can be configured to measure the temperature of the space between the chambers within the catalyst chamber 11. A differential pressure gauge PDT can be installed in the catalyst chamber 11, and can be configured to measure the pressure difference between the inlet-side pressure and the outlet-side pressure of the catalyst chamber 11.

[0135] The controller 20 can control the operation of the inlet valve 13, outlet valve 14, bypass valve 15, etc., based on the methane concentration in the exhaust gas measured by the inlet-side methane dosimeter 16, the methane concentration in the exhaust gas measured by the outlet-side methane dosimeter 17, the temperature measured by the inlet-side temperature sensor T1, the temperature measured by the outlet-side temperature sensor T2, the temperature of the space between the upstream catalyst 21 and the downstream catalysts 31 and 32 measured by the intermediate temperature sensor T3, and the pressure measured by the differential pressure gauge PDT.

[0136] Furthermore, ships according to embodiments of the present invention may include exhaust gas after-treatment systems according to the above embodiments.

[0137] The subject matter disclosed above is to be considered illustrative rather than restrictive, and the appended claims are intended to cover all such modifications, alterations, and other embodiments that fall within the true spirit and scope of the invention.

[0138] Therefore, the embodiments of the present invention are to be considered illustrative rather than restrictive, and the technical spirit of the invention is not limited to the above embodiments. Thus, the scope of the invention is not defined by the detailed description thereof, but by the appended claims, and all differences within that scope shall be construed as included in the invention.

Claims

1. Exhaust gas after-treatment system, including: A multi-fuel engine configured to selectively use two or more different types of fuel; and A catalytic converter is disposed downstream of the multifuel engine and includes an upstream catalyst and a downstream catalyst disposed downstream of the upstream catalyst.

2. The waste gas aftertreatment system as described in claim 1, wherein the content of the catalyst composition of the upstream catalyst is relatively higher than the content of the catalyst composition of the downstream catalyst.

3. The waste gas after-treatment system as described in claim 1, wherein the content of precious metals in the upstream catalyst is relatively higher than the content of precious metals in the downstream catalyst.

4. The exhaust gas aftertreatment system as described in claim 1, further comprising: An inlet-side exhaust gas line connects the multi-fuel engine to the inlet of the catalytic converter. and An outlet-side exhaust gas pipeline is connected to the outlet of the catalytic chamber.

5. Exhaust gas after-treatment system, including: A multi-fuel engine configured to selectively use two or more different types of fuel; A catalytic converter, disposed downstream of the multifuel engine, includes an upstream catalyst and a downstream catalyst disposed downstream of the upstream catalyst; An injector mechanism configured to inject an oxidizable substance into the upstream catalyst upstream of the upstream catalyst; and A controller configured to control the injector mechanism.

6. The exhaust gas aftertreatment system of claim 5, wherein the injector mechanism is a diesel injector mechanism configured to inject diesel fuel into the upstream catalyst.

7. The exhaust gas aftertreatment system of claim 6, wherein the diesel injector mechanism comprises: A diesel fuel injector configured to inject the diesel fuel into the upstream catalyst; and A fuel pump unit configured to supply diesel fuel to the diesel injector.

8. The exhaust gas aftertreatment system of claim 5, wherein the injector mechanism is a urea injector mechanism configured to inject urea into the upstream catalyst.

9. The exhaust gas aftertreatment system of claim 8, wherein the urea injector mechanism comprises: A urea injector configured to inject urea into the upstream catalyst; and A urea metering unit is fluidly connected to the urea injector via a urea pipeline.

10. Exhaust gas after-treatment system, including: A multi-fuel engine configured to selectively use two or more different types of fuel; A catalytic converter, disposed downstream of the multifuel engine, comprising an upstream catalyst and a downstream catalyst located downstream of the upstream catalyst; and A regenerated gas supply device configured to supply regenerated gas to the inlet of the catalytic chamber.

11. The exhaust gas aftertreatment system of claim 10, wherein the regenerated gas comprises a reducing agent and an inert gas.

12. The waste gas aftertreatment system of claim 10, wherein the regeneration gas supply device comprises: A reducing agent supply unit, the reducing agent supply unit being configured to supply a reducing agent; and An inert gas supply unit configured to supply inert gas.

13. The exhaust gas aftertreatment system of claim 12, wherein the inert gas supply unit further includes a heater configured to heat the inert gas.

14. The exhaust gas aftertreatment system of claim 10, further comprising a water injector mechanism configured to inject water into the downstream catalyst.

15. A ship, comprising the exhaust gas aftertreatment system of any one of claims 1, 5 and 10.

Images