Direct-coupled single-module post-treatment system

Abstract

Post-treatment system (300), comprising: a filter and reduction unit (318), comprising: a housing (319) that determines an internal volume; a filter (320) which is arranged in the internal volume of the housing (319); a selective catalytic reduction system (350) which is arranged downstream of the filter (320) in the internal volume of the housing (319), wherein the selective catalytic reduction system (350) is configured to selectively decompose components of an exhaust gas flowing through the aftertreatment system (300); an inlet pipe (302) which is arranged upstream of the housing (319) and which divides into a first inlet pipe (302a) connected to a first location of the housing (319) and into a second inlet pipe (302b) connected to a second location of the housing (319); a first catalyst (310) designed to oxidize at least a portion of the exhaust gas, and arranged in each of the inlet pipes (302a, 302b); and an exhaust pipe (380) which is arranged downstream of the filter and reduction unit (318).

Description

TECHNICAL FIELD

[0001] The present disclosure generally relates to exhaust aftertreatment systems for use with internal combustion (IC) engines. BACKGROUND

[0002] During the combustion process in an internal combustion engine (for example, a diesel engine), sulfur is released simultaneously with carbon monoxide (CO) and hydrocarbons (HC), such as various sulfur oxides (SO X ), which typically contains 97-99% of the total amount of SO present in the exhaust gas X Sulfur dioxide (SO2) and 1-3% sulfur trioxide (SO3). Fuels with higher sulfur content tend to produce larger amounts of SO3. For example, a fuel with a sulfur content of 1000 ppm can produce approximately 1-3 ppm of SO3.

[0003] Exhaust aftertreatment systems are used to capture and treat exhaust gases produced by IC engines. Conventional exhaust aftertreatment systems include any number of different components to reduce the proportion of harmful exhaust emissions in the exhaust. For example, certain exhaust aftertreatment systems for diesel-powered internal combustion engines may include a selective catalytic reduction (SCR) catalyst to convert NO X (NO and NO2 in minor proportions) into harmless nitrogen gas (N2) and water vapor (H2O) in the presence of ammonia (NH3). Generally, in such state-of-the-art aftertreatment systems, an exhaust gas reductant (e.g., a diesel exhaust fluid such as urea) is injected into the aftertreatment system to provide a source of ammonia and mixed with the exhaust gas to reduce the SO X and / or NO X-gases. The byproducts of the reduction of the exhaust gas are then fluidly transferred to the catalyst, which is included in the SCR aftertreatment system, to remove essentially all SO X - and NO X -gases into relatively harmless by-products that are emitted from such state-of-the-art SCR aftertreatment systems.

[0004] State-of-the-art aftertreatment systems may also include one or more catalysts for pretreatment and / or aftertreatment of the exhaust gas. For example, some state-of-the-art aftertreatment systems for treating diesel exhaust may also include a diesel oxidation catalyst and / or an ammonium oxidation catalyst. Other components may also include a filter. Each of these components in state-of-the-art aftertreatment systems is located within the length constraints of the aftertreatment system imposed by the dimensions (e.g., length) of the engine generating the exhaust gas. While it is desirable to maximize the residence time of the exhaust gas in the SCR system, aftertreatment length constraints may limit the dimensions of the aftertreatment system components.From JP 2006- 342 737 A an exhaust emission control device for purifying the exhaust gas of an engine is known, which is provided with a particulate filter for filtering particles in the exhaust gas and a NO. x -Catalyst for the reduction of NO xin the exhaust gas using ammonia as a reducing agent. US 2015 / 0 275 801 A1 describes an exhaust gas purification device in which, when a first temperature of the exhaust gas on an upstream side of the device is lower than a first target temperature, multi-stage temperature rise injection is performed, and when the first temperature reaches the first target temperature or more, post-injection is performed in addition to the multi-stage temperature rise injection. US 2011 / 0 030 350 A1 discloses an exhaust gas purification device comprising an oxidation catalyst provided in a passage through which exhaust gas flows, a urea decomposition accelerator, a selective catalytic reduction catalyst provided downstream of the urea decomposition accelerator, and a urea water supply device for supplying urea water to the urea decomposition accelerator.JP 2007-239 486 A describes an exhaust gas purification device equipped with a catalyst for reducing and purifying NOx (nitrogen oxide) in the exhaust gas using a reducing agent. Nova & Tronconi's "Urea-SCR Technology for deNOx After Treatment of Diesel Exhausts" (2014) demonstrates various layout concepts for integrating oxidation catalysts, particulate filters, and reduction catalysts into an exhaust gas aftertreatment system. DE 43 38 327 A1 describes a method for producing an exhaust gas catalyst in which a carrier film and a separating film are each coated on both sides with a catalyst material, preferably platinum, and wound together on a mandrel to form a wound body. SUMMARY

[0005] Embodiments described herein relate to exhaust aftertreatment systems and methods according to the appended claims 1 and 8. Preferred embodiments are defined by the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The foregoing and other features of the present disclosure will become more apparent from the following description and appended claims, which should be read in conjunction with the accompanying drawings. While these drawings illustrate only some implementations according to the disclosure and are therefore not to be considered limiting in scope, the disclosure is described in additional specificity and detail by means of the accompanying drawings. Fig. 1 is a schematic block diagram of an aftertreatment system including a first catalyst and optionally a second catalyst according to one embodiment. Fig. 2 is a side cross-sectional view of an aftertreatment system according to another embodiment. Fig. 3 is a side cross-sectional view of an aftertreatment system according to yet another embodiment. Fig. 4 is a schematic flow diagram of an exemplary method for increasing space available within an interior volume defined by an aftertreatment system enclosure for accommodating various aftertreatment components therein.

[0007] Throughout the following detailed description, reference is made to the accompanying drawings. In the drawings, like symbols normally identify like components unless the context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not intended to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. It is contemplated that the aspects of the present disclosure, as generally described herein and illustrated in the drawings, may be arranged, substituted, combined, and designed in many different configurations, all of which are expressly contemplated and constitute a part of this disclosure. DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

[0008] Embodiments described herein relate generally to exhaust aftertreatment systems for use with internal combustion engines, and more particularly to exhaust aftertreatment systems that include an oxidation catalyst disposed in an inlet pipe of the aftertreatment system. The embodiments described herein may provide certain advantages, such as: (1) disposing a first oxidation catalyst in an inlet pipe, thereby allowing more space for an SCR system filter and / or a static mixer to be disposed within the aftertreatment system; (2) disposing a second oxidation catalyst in an exhaust pipe, thereby providing even more space for disposing the SCR system, filter, and / or static mixer within the aftertreatment system; (3) allowing an increase in dimensions (e.g.,length and / or width) of the SCR system and / or static mixer relative to prior art aftertreatment systems without increasing the overall length of the aftertreatment system; (4) increasing the residence time of the exhaust gas or exhaust / exhaust reductant mixture within the aftertreatment system, which may result in better mixing, increased efficiency of the SCR catalysts, higher temperatures, fewer deposits, and / or lower backpressure; (5) reducing heat loss, thereby reducing the amount and cost of insulation; and (6) providing better dispersion of particulate matter (e.g., soot) entrained in the exhaust gas flowing through the aftertreatment system.

[0009] Fig. 1 shows an exhaust aftertreatment system 100 for treating an exhaust gas (e.g., diesel exhaust) produced by an internal combustion engine (e.g., a diesel engine). The aftertreatment system 100 includes an intake pipe 102, a first catalyst 110, a filter and reduction unit 118 including a filter 120 and a selective catalytic reduction (SCR) system 150, and an exhaust pipe 180. The aftertreatment system 100 may optionally also include a second catalyst 170.

[0010] The inlet pipe 102 is arranged upstream of the filter and reduction unit 118. The inlet pipe 102 is configured to receive an exhaust gas (e.g., diesel exhaust) from an internal combustion engine (e.g., a diesel engine) and direct the exhaust gas to the filter and reduction unit 118. The inlet pipe 102 may be made of a strong, rigid, heat- and / or corrosion-resistant material such as metals (e.g., stainless steel, aluminum alloys, etc.), ceramic, any other suitable material, or a combination thereof. The inlet pipe 102 may have a suitable cross-section, for example, a circular, square, rectangular, polygonal, oval, or any other suitable cross-section.

[0011] The first catalyst 110, for example, a first oxidation catalyst, is configured to oxidize at least a portion of the exhaust gas flowing through the first catalyst 120. In some embodiments where the exhaust gas is diesel exhaust, the first catalyst 120 may include, for example, a diesel oxidation catalyst. The diesel oxidation catalyst may be configured to oxidize carbon monoxide, hydrocarbons, and / or particulate matter contained in the exhaust stream. Furthermore, the diesel oxidation catalyst may be configured to have a low light-off temperature and / or a high tolerance for sulfur (e.g., SO X -gases contained in the exhaust gas). Suitable diesel oxidation catalysts may include, for example, platinum, palladium, alumina, or a combination thereof.

[0012] The first catalyst 110 is disposed within a flow path defined by the inlet pipe 102. In one embodiment, the first catalyst 110 may be fixedly disposed within the inlet pipe 102. In other embodiments, the first catalyst 110 may be removably disposed within the inlet pipe 102, for example, to allow replacement of the first catalyst 110 without replacing the inlet pipe 102. In some embodiments, the inlet pipe 102 may divide or otherwise split into a plurality of inlet pipes, each of which is fluidly connected to the filtration and reduction unit 118. In other words, the inlet pipe 102 may divide the exhaust flow into a plurality of portions, which are then delivered to the filtration and reduction unit 118.In such embodiments, the first catalyst 110 may be disposed in each of the plurality of inlet pipes leading into the filter and reduction unit 118. In one embodiment, for example, the inlet pipe 102 may split into a first inlet pipe and a second inlet pipe, and the first catalyst 110 may be disposed in each of the first inlet pipe and the second inlet pipe.

[0013] A plurality of temperature sensors may also be disposed in the intake pipe 102 to measure a temperature of the exhaust gas at various locations within the intake pipe (e.g., before contacting the first catalyst 110 and / or after flowing through the first catalyst 110).

[0014] The filter and reduction unit 118 includes a housing (not shown) that defines an internal volume. The housing may be formed from any suitable material, for example, metals or ceramics. The housing may define any suitable cross-section, for example, a circular, square, rectangular, polygonal, elliptical, or any other suitable cross-section.

[0015] The filter 120 is disposed within the internal volume defined by the housing. The filter 120 is configured to receive the exhaust stream (e.g., diesel exhaust) from the intake pipe 102. The filter 120 may include any suitable filter (e.g., a diesel particulate filter) configured to filter and remove any particulate matter entrained in the exhaust stream and prevent such particulate matter from entering the SCR system 150. Such particulate matter may include, for example, dust, soot, organic particles, crystals, or other solid particles contained in the exhaust. The filter 120 may include a filter housing constructed from a strong and rigid material, such as high-density polypropylene (HDPP), which may define an internal volume to house a filter element.Any suitable filter element may be used, such as a cotton filter element, an acrylonitrile butadiene styrene (ABS) filter element, any other suitable filter element, or a combination thereof. The filter element may have any suitable pore size, for example, about 10 microns, about 5 microns, or about 1 micron.

[0016] One or more temperature sensors may be disposed in or otherwise near the filter 120 (e.g., at the inlet of the filter 120) to measure the temperature of the exhaust gas.

[0017] Furthermore, a pressure sensor may also be disposed on the filter 120 to measure any pressure changes in the exhaust gas flowing through the filter 120. In some embodiments, the pressure sensor may include a differential pressure sensor disposed across the filter 120 to determine a differential pressure thereacross. In other embodiments, the pressure sensor may include a first pressure sensor positioned upstream of the filter 120 and a second pressure sensor positioned downstream of the filter 120. The first pressure sensor measures a first pressure upstream of the filter 120, and the second pressure sensor measures a second pressure downstream of the filter 120. The difference between the first pressure and the second pressure represents the pressure drop across the filter 120.For example, a change in exhaust gas pressure or pressure drop across filter 120 may provide information about the amount of particulate matter trapped within filter 110 and / or the remaining life of filter 110. A change in exhaust gas pressure above a predetermined threshold may indicate, for example, that filter 120 is significantly clogged and should be replaced.

[0018] In some embodiments, a static mixer (not shown) may also be included in the aftertreatment system 100. In such embodiments, the static mixer may be disposed within the internal volume defined by the housing. The static mixer may be disposed downstream of the filter 120 and upstream of the SCR system 150 and configured to fluidly couple the filter 120 to the SCR system 150. The static mixer may include a static mixer housing defining an internal volume. An injection port may be disposed on a sidewall of the static mixer housing and configured to direct an exhaust reductant into the static mixer. In some embodiments, the exhaust gas may include diesel exhaust, and the exhaust reductant may include diesel exhaust fluid.The diesel emission fluid may comprise urea, an aqueous urea solution, any other ammonia-containing fluid, by-products, or any other diesel emission fluids known in the art (e.g., the diesel emission fluid marketed under the name ADBLUE®).

[0019] The static mixer may be structured to enable efficient mixing of the exhaust reductant with the exhaust gas before the exhaust gas is directed into the SCR system 150. The static mixer may include any suitable structures, such as passages, baffles, baffles, partitions, or any other elements or structures to facilitate mixing of the exhaust reductant with the exhaust gas.

[0020] The SCR system 150 is disposed within the internal volume defined by the housing of the filter and reduction unit 118. The SCR system 150 is disposed downstream of the filter 120 and is configured to treat an exhaust gas (e.g., diesel exhaust) that flows through the SCR system 150. The SCR system 150 is configured to selectively reduce a portion of the exhaust gas. For example, the exhaust gas reductant may react with the exhaust gas to remove one or more components of the gas (e.g., SO X and NO X ) or to promote the reduction of one or more components in the presence of one or more catalysts included in the SCR system 150. One or more temperature sensors may also be arranged in the SCR system 150 to measure a temperature of the exhaust gas.

[0021] The SCR system 150 includes one or more catalysts designed to selectively reduce the exhaust gas. Any suitable catalyst may be used, such as a platinum-, palladium-, rhodium-, cerium-, iron-, manganese-, copper-, vanadium-based catalyst, any other suitable catalyst, or a combination thereof. The catalyst may be disposed on a suitable substrate, such as a ceramic (e.g., cordierite) or metallic (e.g., Kanthai) monolith core, which may, for example, have a honeycomb structure. A washcoat (intermediate layer) may also be used as a support material for the catalysts. Such washcoat materials may include, for example, alumina, titania, silica, any other suitable washcoat material, or a combination thereof. The exhaust gas (e.g.,Diesel exhaust gas) can flow over and around the catalyst in such a way that all SO contained in the exhaust gas. X - or NO X -gases are further reduced, resulting in an exhaust gas that is essentially free of carbon monoxide and SO X - or NO X -gases.

[0022] The exhaust pipe 180 is disposed downstream of the filter and reduction unit 118. The exhaust pipe 180 may be formed from substantially the same materials as the inlet pipe 102. The exhaust pipe 180 is configured to receive the treated exhaust gas (or other mixture of treated exhaust gas and any excess exhaust reductant (e.g., urea) or its byproducts (e.g., ammonia)) and discharge it to the outside environment. One or more sensors may also be disposed in the exhaust pipe 180 to measure a concentration of one or more components of the exhaust gas. In some embodiments where the exhaust gas includes diesel exhaust, for example, NO X -Sensors, SO X -Sensors and / or exhaust gas reducing agent sensors (e.g. ammonia) may be arranged in the exhaust pipe 180.

[0023] In some embodiments, the aftertreatment system 100 may also include a second catalyst 170 (e.g., a second oxidation catalyst). In one embodiment, the second catalyst 170 may be located downstream of the SCR system 150 and upstream of the exhaust pipe 180 in the internal volume defined by the housing of the filter and reduction unit 118. In other embodiments, the second catalyst 170 may be located in the exhaust pipe 180.

[0024] The second catalyst 170 may be configured to oxidize any excess exhaust reductant contained in the exhaust gas exiting the SCR system 150. For example, the exhaust reductant may be a diesel exhaust fluid (e.g., an aqueous solution of urea, as described herein) that provides a source of ammonia to participate in the selective catalytic reduction in the SCR system 150. In such embodiments, the second catalyst 170 may include an ammonium oxidation catalyst configured to oxidize ammonia to nitrogen. Suitable catalysts may include platinum, palladium, iridium, ruthenium, silver, metal oxides (e.g., CO3O4, MnO2, V2O5, etc.), Ni, Fe and / or Mn supported on Al2O3, CuO / Al2O3, Fe2O3 / Al2O3, Fe2O3 / TiO2, Fe2O3 / ZrO2, zeolites (e.g., mordenite, ferrierite, chabazite), any other suitable ammonia oxidation catalyst, or a combination thereof.

[0025] As described herein, the first catalyst 110 is disposed in the intake pipe 102. Furthermore, the second catalyst 170 may also be disposed in the exhaust pipe 180. This may allow a dimension (e.g., a length) of the filtration and reduction unit 118 (e.g., the housing of the filtration and reduction unit 118 or a length of the filter 120 and / or the SCR system 150) to be increased without increasing the overall dimension (e.g., length) of the housing of the filtration and reduction unit 118 of the aftertreatment system 100.

[0026] The distance between an outlet of the intake pipe (i.e., the end connected to the housing of the aftertreatment system 100) and an inlet of the exhaust pipe (i.e., the end connected to the housing of the aftertreatment system 100) determines the length of an aftertreatment system body, for example, the housing of the filter and reduction unit 118. In prior art aftertreatment systems, each component of the aftertreatment system, for example, a first catalyst (e.g., a diesel oxidation catalyst), a filter (e.g., a diesel particulate filter), a mixer, an SCR system, and / or the second catalyst (e.g., an ammonium oxidation catalyst), is disposed between the inlet pipe and the exhaust pipe. This creates a limit on the length of the SCR system, the filter, and the static mixer.

[0027] In contrast, the aftertreatment system 100 allows the first catalyst 110 to be disposed within the intake pipe 102 and the second catalyst 170 to be disposed within the exhaust pipe 180. In this way, the distance between the outlet of the intake pipe 102 and the inlet of the exhaust pipe 180 remains the same, but now the entire length of the housing of the filter and reduction unit 118 is available for arranging the filter 120, the static mixer, and the SCR system 150. This allows a length of the filter and reduction unit 118 (i.e., the length of the SCR system 150, the static mixer, and / or the filter 110) to be increased relative to prior art aftertreatment systems.

[0028] The increased length may increase the residence time of the exhaust gas (or otherwise a mixture of the exhaust gas and the exhaust reductant) within the filter 110, the static mixer, and / or the SCR system 150. The increased residence time may provide several benefits, such as more efficient mixing of the exhaust reductant with the exhaust gas, more efficient reduction of SO X - and / or NO X Gases contained in the exhaust gas (e.g., diesel exhaust) may experience increased temperature and / or reduced backpressure. Furthermore, positioning the first catalyst 110 within the intake pipe 102 may prevent heat loss by allowing the utilization of the heat of the oxidation reaction taking place in or on the first catalyst 110 (e.g., within pores defined by the first catalyst 110 or on a surface of the first catalyst 110).

[0029] Fig. Figure 2 shows a side cross-sectional view of an aftertreatment system 200 that may be used to treat an exhaust gas (e.g., diesel exhaust) produced by an internal combustion engine (e.g., a diesel engine). The aftertreatment system 200 includes an intake pipe 202, a first catalyst 210, a filter and reduction unit 218 including a filter 220, a static mixer 230, and an SCR system 250, a second catalyst 270, and an exhaust pipe 280.

[0030] The inlet pipe 202 is disposed upstream of the filter and reduction unit 218 and is configured to receive an exhaust gas (e.g., diesel exhaust) from an internal combustion engine (e.g., a diesel engine) and direct the exhaust gas to the filter 220. The inlet pipe 202 may be made of a strong, rigid, heat- and / or corrosion-resistant material such as metals (e.g., stainless steel, aluminum alloys, etc.), ceramic, any other suitable material, or a combination thereof. The inlet pipe 202 may have a suitable cross-section, for example, a circular, square, rectangular, polygonal, oval, or any other suitable cross-section.

[0031] The first catalyst 210 is configured to oxidize at least a portion of the exhaust gas flowing through the first catalyst 210. In some embodiments where the exhaust gas is diesel exhaust, the first catalyst 210 may include, for example, a diesel oxidation catalyst. The diesel oxidation catalyst may be configured to oxidize carbon monoxide, hydrocarbons, and / or particulate matter contained in the exhaust stream. Furthermore, the diesel oxidation catalyst may be configured to have a low light-off temperature and a high tolerance for sulfur (e.g., SO X -gases contained in the exhaust gas). Suitable diesel oxidation catalysts may include, for example, platinum, palladium, alumina, or a combination thereof.

[0032] As in Fig. 2, the first catalyst 210 is arranged within a flow path defined by the inlet pipe 202. The first catalyst 210 can be fixedly or removably arranged in the flow path, for example, to enable replacement of the first catalyst 210 without replacing the inlet pipe 202. A first temperature sensor 216a is arranged upstream of the first catalyst 210 in the inlet pipe 202, and a second temperature sensor 216b is also arranged downstream of the first catalyst 210 in the inlet pipe 202.

[0033] The first temperature sensor 216a and the second temperature sensor 216b are configured to measure the temperature of the exhaust gas entering the intake pipe 202 and leaving the intake pipe 202, respectively, after passing through the first catalyst 210.

[0034] The filter and reduction unit 218 includes a housing 219 defining an internal volume. The housing 219 may be formed from any suitable material, for example, metals or ceramics. Furthermore, the housing 219 may define a suitable cross-section, for example, a circular, square, rectangular, polygonal, elliptical, or any other suitable cross-section.

[0035] The filter 220 is disposed within the internal volume defined by the housing 219. The filter 220 is disposed downstream of the inlet pipe 202 and upstream of the static mixer 230. The filter 220 is configured to receive the exhaust stream (e.g., diesel exhaust) from the inlet pipe 202. The filter 220 may include any suitable filter (e.g., a diesel particulate filter) configured to filter and remove any particulate matter entrained in the exhaust stream and prevent such particulate matter from entering the SCR system 250. Such particulate matter may include, for example, dust, soot, organic particles, crystals, or other solid particles contained in the exhaust gas.The filter 220 may include a filter housing constructed from a strong and rigid material, such as high-density polypropylene (HDPP), which may define an internal volume to house a filter element. Any suitable filter element may be used, such as a cotton filter element, an acrylonitrile butadiene styrene (ABS) filter element, any other suitable filter element, or a combination thereof. The filter element may have any suitable pore size, for example, about 10 microns, about 5 microns, or about 1 micron.

[0036] A temperature sensor 226 is disposed near an inlet of the filter 220 and is configured to measure a temperature of the exhaust gas flowing into the filter 220. A pressure sensor 222 is disposed above the filter 220 and may include, for example, a differential pressure sensor. The pressure sensor 222 is configured to measure a differential pressure, or pressure drop, of the exhaust gas flowing through the filter 220. The pressure sensor 222 may be used, for example, to determine a performance efficiency or other remaining lifespan of the filter 220. For example, a drop in exhaust pressure above a predetermined threshold may indicate that the filter 220 is clogged and / or needs to be replaced.

[0037] The static mixer 230 is disposed downstream of the filter 220 and upstream of the SCR system 250 in the internal volume defined by the housing 219, and fluidly couples the filter 220 to the SCR system 250. The static mixer 230 may include a static mixer housing defining an internal volume. An injection port 240 is disposed on a sidewall of the static mixer 230 and configured to direct an exhaust reductant into the static mixer 230. In some embodiments, the exhaust gas may include diesel exhaust, and the exhaust reductant may include a diesel exhaust fluid. The diesel emission fluid may comprise urea, an aqueous urea solution, or any other ammonia-containing fluid, by-products, or any other diesel emission fluids known in the art (e.g., the diesel emission fluid marketed under the name ADBLUE®).A temperature sensor 236 is disposed near an inlet of the static mixer 230. The temperature sensor 236 may be configured to measure a temperature of the exhaust gas flowing into the static mixer 230.

[0038] The static mixer 230 is structured to enable efficient mixing of the exhaust reductant with the exhaust gas before the exhaust gas is directed into the SCR system 250. The static mixer 230 may include any suitable structures, such as passages, baffles, baffles, dividers, or any other elements or structures to facilitate mixing of the reductant with the exhaust gas, increase residence time, increase temperature, reduce deposition of the exhaust reductant, and / or reduce backpressure.

[0039] The SCR system 250 is disposed downstream of the static mixer 230 within the internal volume defined by the housing 219 and is configured to treat an exhaust gas (e.g., diesel exhaust) flowing through the SCR system 250. The SCR system 250 is configured to selectively reduce a portion of the exhaust gas. The exhaust gas reductant reacts with the exhaust gas, for example, in the presence of the catalysts included in the SCR system 250, to reduce one or more components of the gas (e.g., SO X - and / or NO X -gases) or to promote the reduction of one or more components in the presence of one or more catalysts. A temperature sensor 256 is disposed near an outlet of the SCR system 250. The temperature sensor 256 may be configured to measure a temperature of the exhaust gas flowing from the filter and reduction unit 218 into the exhaust pipe 280.

[0040] The SCR system 250 includes one or more catalysts designed to selectively reduce the exhaust gas. Any suitable catalyst may be used, such as a platinum-, palladium-, rhodium-, cerium-, iron-, manganese-, copper-, vanadium-based catalyst, any other suitable catalyst, or a combination thereof. The catalyst may be disposed on a suitable substrate, such as a ceramic (e.g., cordierite) or metallic (e.g., Kanthai) monolith core, which may, for example, have a honeycomb structure. A washcoat (intermediate layer) may also be used as a support material for the catalysts. Such washcoat materials may include, for example, alumina, titania, silica, any other suitable washcoat material, or a combination thereof. The exhaust gas (e.g.,Diesel exhaust gas) can flow over and around the catalyst in such a way that all SO contained in the exhaust gas. X - or NO X -gases are further reduced, resulting in an exhaust gas that is essentially free of carbon monoxide and SO X - or NO X -gases.

[0041] The exhaust pipe 280 is disposed downstream of the filter and reduction unit 218. The exhaust pipe 280 may be formed from substantially the same materials as the inlet pipe 202. The exhaust pipe 280 is configured to receive the treated exhaust gas (or other mixture of the treated exhaust gas and any excess exhaust reductant (e.g., urea) or its byproducts (e.g., ammonia)) and discharge it to the external environment.

[0042] The second catalyst 270 is disposed in the exhaust pipe 280. The second catalyst 270 may be configured to oxidize any excess exhaust reductant remaining in the exhaust gas exiting the SCR system 250.

[0043] In some embodiments, the exhaust reductant may be a diesel exhaust fluid (e.g., an aqueous solution of urea, as described herein) that provides a source of ammonia to participate in the selective catalytic reduction in the SCR system 250. In such embodiments, the second catalyst 270 may include an ammonium oxidation catalyst configured to oxidize ammonia to nitrogen. Suitable catalysts may include platinum, palladium, iridium, ruthenium, silver, metal oxides (e.g., CO3O4, MnO2, V2O5, etc.), Ni, Fe and / or Mn supported on Al2O3, CuO / Al2O3, Fe2O3 / Al2O3, Fe2O3 / TiO2, Fe2O3 / ZrO2, zeolites (e.g., mordenite, ferrierite, chabazite), any other suitable ammonia oxidation catalyst, or a combination thereof.

[0044] A temperature sensor 276 is disposed in the exhaust pipe 280 and configured to measure a temperature of the exhaust gas leaving the exhaust pipe 280 after flowing through the second catalyst 270. Also disposed in the exhaust pipe 280 are a first gas sensor 272 and a second gas sensor 274, which may be configured to measure a concentration of a portion of a gas contained in the exhaust gas leaving the exhaust pipe 280. In some embodiments, the exhaust gas may be diesel exhaust. In such embodiments, the first gas sensor 272 may measure a NO X -Sensor and / or a SO X -Sensor configured to detect a concentration of NO X - and / or SO X-gases contained in the exhaust gas exiting the exhaust pipe 280. Furthermore, the second gas sensor 274 may include an ammonia sensor configured to measure an ammonia concentration in the exhaust gas (e.g., a decomposition product of a diesel exhaust fluid such as urea).

[0045] As described herein, the first catalyst 210 is disposed in the intake pipe 202, and the second catalyst 270 is disposed in the exhaust pipe 280. This may allow a dimension (e.g., a length) of the SCR system 250, the static mixer 230, and / or the filter 220 to be increased without increasing the overall dimension (e.g., length) of the filter and reduction unit 218. In this way, the filter and reduction unit 218 may provide extended exhaust residence time, higher exhaust temperature, more effective NO X - and SO X -Provide exhaust gases and / or reduced back pressure.

[0046] Fig. 3 is a side cross-sectional view of another embodiment of an aftertreatment system 300 that may be used to treat an exhaust gas (e.g., diesel exhaust) produced by an internal combustion engine (e.g., a diesel engine). The aftertreatment system 300 includes an intake pipe 302, a first catalyst 310, a filter and reduction unit 318 including a filter 320, a static mixer 330, and an SCR system 350, a second catalyst 370, and an exhaust pipe 380.

[0047] The inlet pipe 302 is disposed upstream of the filter and reduction unit 318 and is configured to receive an exhaust gas (e.g., diesel exhaust) from an internal combustion engine (e.g., a diesel engine) and direct the exhaust gas to the filter and reduction unit 318. The inlet pipe 302 may be made of a strong, rigid, heat- and / or corrosion-resistant material such as metals (e.g., stainless steel, aluminum alloys, etc.), ceramic, any other suitable material, or a combination thereof. The inlet pipe 302 may have any suitable cross-section, for example, a circular, square, rectangular, polygonal, oval, or any other suitable cross-section.

[0048] The inlet pipe 302 splits at a Y-junction into a first inlet pipe 302a and a second inlet pipe 302b. The first inlet pipe 302a and the second inlet pipe 302b are configured to divide the intake flow of the exhaust gas into a first intake flow and a second intake flow, which are then directed to the filter and reduction unit 318.

[0049] The first catalyst 310 is disposed in a first flow path defined by the first inlet pipe 302a and also in a second flow path defined by the second inlet pipe 302b. The first catalyst 310 is configured to oxidize at least a portion of the exhaust gas flowing through the first inlet pipe 302a and the second inlet pipe 302b. In some embodiments where the exhaust gas is diesel exhaust, the first catalyst 310 may include, for example, a diesel oxidation catalyst. The diesel oxidation catalyst may be configured to oxidize carbon monoxide, hydrocarbons, and / or particulate matter contained in the exhaust stream. Furthermore, the diesel oxidation catalyst may be configured to provide a low light-off temperature and a high tolerance for sulfur (e.g., SO X-gases contained in the exhaust gas). Suitable diesel oxidation catalysts may include, for example, platinum, palladium, alumina, or a combination thereof.

[0050] A first temperature sensor 316a is disposed in the first inlet pipe 302a upstream of the first catalyst 310, and a second temperature sensor 316b is disposed in the first inlet pipe 302a downstream of the first catalyst 310. Furthermore, a third temperature sensor 316c is disposed in the second inlet pipe 302b upstream of the first catalyst 310, and a fourth temperature sensor 316d is also disposed in the second inlet pipe 302b downstream of the first catalyst 310. The first temperature sensor 316a and the second temperature sensor 316b are configured to measure the temperature of the exhaust gas entering the first inlet pipe 302a and exiting the first inlet pipe 302a, respectively, after flowing through the first catalyst 310. The third temperature sensor 316c and the fourth temperature sensor 316d are similarly configured to measure the temperature of the exhaust gas entering and leaving the second inlet pipe 302b, respectively.leaves the second inlet pipe 302b after flowing through the first catalyst 310.

[0051] While shown as dividing into the first intake pipe 302a and the second intake pipe 302b, the intake pipe 302 may be divided or otherwise split into a number of intake pipes to divide the exhaust gas intake flow into a plurality of intake flows. Dividing the flow may, for example, reduce exhaust gas backpressure or enable more efficient interaction of the intake flow with the first catalyst 310.

[0052] The filter and reduction unit 318 includes a housing 319 defining an internal volume. The housing 319 may be substantially similar to the housing 219 described with respect to the aftertreatment system 200 and is therefore not described in more detail here. The filter 320 is disposed upstream of the static mixer 330 within the internal volume defined by the housing 319. The filter 320 is configured to receive the flow of exhaust gas (e.g., diesel exhaust) from the first inlet pipe 302a and the second inlet pipe 302b and to substantially remove particulate matter from the exhaust gas. The filter 320 may be substantially similar to the filter 220 described with respect to the aftertreatment system 200 and is therefore not described in more detail here.

[0053] A temperature sensor 326 is disposed near an inlet of the filter 320 and configured to measure a temperature of the exhaust gas flowing into the filter 320. A pressure sensor 322, such as a differential pressure sensor, is also disposed above the filter 320. The pressure sensor 322 may be configured to measure a pressure differential of the exhaust gas flowing through the filter 320. The pressure sensor 322 may be used, for example, to determine power efficiency or otherwise remaining life of the filter 320. For example, a drop in exhaust pressure above a predetermined threshold may indicate that the filter 320 is clogged and / or needs to be replaced.

[0054] The static mixer 330 is arranged downstream of the filter 320 and upstream of the SCR system 350 in the internal volume defined by the housing 319, and fluidly couples the filter 320 to the SCR system 350. The static mixer 330 may include a static mixer housing that defines an internal volume. An injection port 340 is arranged on a side wall of the static mixer 330 and is configured to direct an exhaust gas reducing agent into the static mixer 330.

[0055] In some embodiments, the exhaust gas may include diesel exhaust, and the exhaust reductant may include a diesel exhaust fluid. The diesel exhaust fluid may include urea, an aqueous urea solution, or any other ammonia-containing fluid, byproducts, or any other diesel exhaust fluids known in the art (e.g., the diesel exhaust fluid marketed under the name ADBLUE®). A temperature sensor 336 is disposed near an inlet of the static mixer 330. The temperature sensor 336 may be configured to measure a temperature of the exhaust flowing into the static mixer 330.

[0056] The static mixer 330 is structured to enable efficient mixing of the exhaust reductant with the exhaust gas before the exhaust gas is directed into the SCR system 350. The static mixer 330 may include any suitable structures, such as passages, baffles, baffles, partitions, or any other elements or structures to facilitate mixing of the reductant with the exhaust gas, increase residence time, increase temperature, reduce deposition of the exhaust reductant, and / or reduce backpressure.

[0057] The SCR system 350 is disposed downstream of the static mixer 330 within the internal volume defined by the housing 319 and is configured to treat an exhaust gas (e.g., diesel exhaust) flowing through the SCR system 350. The SCR system 350 is configured to selectively reduce a portion of the exhaust gas. The SCR system 350 may be substantially similar to the SCR system 250 described with respect to the aftertreatment system 200 and therefore will not be described in more detail here. A temperature sensor 356 is disposed near an outlet of the SCR system 350. The temperature sensor 356 may be configured to measure a temperature of the exhaust gas flowing from the SCR system into the exhaust pipe 380.

[0058] The exhaust pipe 380 is disposed downstream of the filter and reduction unit 318. The exhaust pipe 380 may be formed from substantially the same materials as the inlet pipe 302. The exhaust pipe 380 is configured to receive the treated exhaust (or other mixture of the treated exhaust and any excess exhaust reductant (e.g., urea) or its byproducts (e.g., ammonia)) and discharge it to the external environment. The second catalyst 370 is disposed in the exhaust pipe 380. The second catalyst 370 may be configured to oxidize any excess exhaust reductant remaining in the exhaust exiting the SCR system 350.

[0059] In some embodiments, the exhaust reductant may be a diesel exhaust fluid (e.g., an aqueous solution of urea, as described herein) that provides a source of ammonia to participate in the selective catalytic reduction in the SCR system 350. In such embodiments, the second catalyst 370 may include an ammonium oxidation catalyst configured to oxidize ammonia to nitrogen, as described herein with respect to the second catalyst 270 included in the aftertreatment system 200.

[0060] A temperature sensor 376 is disposed in the inlet pipe 302 and configured to measure a temperature of the exhaust gas exiting the exhaust pipe 380 after flowing through the second catalyst 370. Furthermore, a first gas sensor 372 and a second gas sensor 374 are also disposed in the exhaust pipe 380 and may be configured to measure a concentration of a portion of a gas contained in the exhaust gas exiting the exhaust pipe 380. In some embodiments, the exhaust gas may be diesel exhaust. In such embodiments, the first gas sensor 372 may measure a NO X -Sensor and / or a SO X -Sensor configured to detect a concentration of NO X - and / or SO X-gases contained in the exhaust gas exiting the exhaust pipe 380. Furthermore, the second gas sensor 374 may include an ammonia sensor configured to measure an ammonia concentration in the exhaust gas (e.g., a decomposition product of a diesel exhaust fluid such as urea).

[0061] In some embodiments, a portion of the exhaust pipe 380 near the filter and reduction unit 318 may also be split or otherwise divided into a plurality of exhaust pipes. For example, two, three, or even more exhaust pipes may be coupled to an outlet of the filter and reduction unit 318 and configured to receive a portion of the treated exhaust gas from the SCR system 350. The plurality of exhaust pipes may then converge at the exhaust pipe 380. In such embodiments, the second catalyst 370 may be disposed in each of the plurality of exhaust pipes.

[0062] Fig.4 is a schematic flow diagram of an example method 400 for increasing the space available within an internal volume defined by a housing (e.g., housing 219 / 319) of an aftertreatment system (e.g., aftertreatment system 100 / 200 / 300). The larger space available within the internal volume defined by the housing enables increasing the dimensions of an SCR system (e.g., SCR system 150 / 250 / 350), a filter (e.g., filter 120 / 220 / 320), and / or a static mixer (e.g., static mixer 230 / 330) positionable within the internal volume defined by housing 219 / 319 or any other housing described herein.

[0063] The method 400 includes positioning an SCR system within the interior volume of the housing at 402. For example, the SCR system 150 / 250 / 350 or otherwise an SCR catalyst is positioned within the interior volume defined by the housing 219 / 319 or any other housing described herein. In some embodiments, a filter is positioned upstream of the SCR system within the interior volume defined by the housing at 404. The filter 120 / 220 / 320 is positioned upstream of the SCR system within the interior volume of the housing 219 / 319 or any other housing described herein such that the filter 120 / 220 / 320 is positioned near the inlet and the SCR system is positioned near an outlet of the housing 219 / 319 or any other housing described herein. In particular embodiments, the method 400 may also include positioning a differential pressure sensor (e.g.,the differential pressure sensor 222 / 322) via the filter 120 / 220 / 320.

[0064] In particular embodiments, a static mixer is positioned upstream of the SCR system and downstream of the filter within the interior volume defined by the housing at 406. The static mixer 230 / 330 is positioned, for example, between the filter 120 / 220 / 320 and the SCR system 150 / 250 / 350 within the interior volume of the housing 219 / 319 or any other housing described herein. The static mixer 230 / 330 may be structured to receive a reductant, for example, via an introduction unit (e.g., a reductant injector) fluidly coupled to the housing 219 / 319 or any other housing described herein, and to facilitate mixing of the reductant with an exhaust gas (e.g., diesel exhaust) flowing through the aftertreatment system 100 / 200 / 300.

[0065] An inlet tube is fluidly coupled to an inlet of the housing at 408. The inlet tube 102 / 202 / 302 is, for example, fluidly coupled to an inlet of the housing 219 / 319 or any other housing described herein. A first catalyst is disposed in the inlet tube at 410. The first catalyst 110 / 210 / 310 is, for example, disposed within the inlet tube 102 / 202 / 302. In particular embodiments, the inlet tube (e.g., inlet tube 302) may be divided into a plurality of inlet tubes, each fluidly coupled to the inlet of the housing 219 / 319 or any other housing described herein. In such embodiments, the first catalyst 110 / 210 / 310 is disposed within each of the plurality of inlet tubes. In some embodiments, the first catalyst 110 / 210 / 310 includes a diesel oxidation catalyst as described herein.

[0066] In some embodiments, method 400 also includes coupling an exhaust conduit to an outlet of the housing at 412. For example, exhaust conduit 180 / 280 / 380 is coupled to an outlet of housing 219 / 319 or any other housing described herein. A second catalyst may be disposed within the exhaust conduit at 414. For example, second catalyst 170 / 270 / 370 may be disposed within exhaust conduit 180 / 280 / 380. In various embodiments, second catalyst 170 / 270 / 370 includes an ammonia oxidation catalyst.

[0067] As used herein, the singular forms "a" and "an" include the plural forms unless the context expressly indicates otherwise. Thus, for example, the term "an element" shall mean a single element or a combination of elements, and "a material" shall mean one or more materials or a combination thereof.

[0068] It should be noted that the term "exemplary" or "example" as used herein to describe various embodiments is intended to indicate that such embodiments are possible examples, representations, and / or illustrations of possible embodiments (and that such term is not necessarily intended to imply that such embodiments are exceptional or excellent examples).

[0069] The terms "coupled," "connected," and the like, as used herein, mean the direct or indirect connection of two elements to one another. This connection can be stationary (e.g., permanent) or movable (e.g., removable or detachable). This connection can be achieved by the two elements, or the two elements and any other intermediate elements, being integrally formed as a unitary body, or by the two elements, or the two elements and any other intermediate elements, being fastened to one another.

[0070] It should be understood that the construction and arrangement of the various exemplary embodiments are for illustrative purposes only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art will readily recognize upon reading this disclosure that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes, and portions of the various elements, values ​​of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter described herein. Other substitutions, modifications, changes, and omissions may also be made in the construction, operating conditions, and arrangement of the various exemplary embodiments without departing from the scope of the present invention.

[0071] Although this specification contains many specific embodiment details, these should not be considered limitations on the scope of all inventions or the claims, but rather as descriptions of features specific to particular embodiments of particular inventions. Certain features described in this specification in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable subcombination.In addition, although the above features may be described as functioning in certain combinations and may also be initially claimed as such, in some cases one or more features from a claimed combination may be singled out from the combination, and the claimed combination may be directed to a sub-combination or variations of a sub-combination.

Claims

[1] Aftertreatment system (300) comprising: a filter and reduction unit (318) comprising: a housing (319) defining an internal volume; a filter (320) arranged in the internal volume of the housing (319); a selective catalytic reduction system (350) disposed in the interior volume of the housing (319) downstream of the filter (320), the selective catalytic reduction system (350) being configured to selectively decompose components of an exhaust gas flowing through the aftertreatment system (300); an inlet pipe (302) arranged upstream of the housing (319) and which divides into a first inlet pipe (302a) connected to a first location of the housing (319) and a second inlet pipe (302b) connected to a second location of the housing (319); a first catalyst (310) configured to oxidize at least a portion of the exhaust gas and disposed in each of the inlet pipes (302a, 302b); and an exhaust pipe (380) arranged downstream of the filter and reduction unit (318). [2] The aftertreatment system (300) of claim 1, wherein the first catalyst (310) is a diesel oxidation catalyst. [3] The aftertreatment system (300) of claim 1, wherein the aftertreatment system (300) further comprises a second catalyst (370) configured to oxidize an exhaust gas reductant. [4] The aftertreatment system (300) of claim 3, wherein the second catalyst (370) is an ammonium oxidation catalyst. [5] Aftertreatment system (300) according to claim 3, wherein the second catalyst (370) is arranged in the exhaust pipe (380). [6] The aftertreatment system (300) of claim 1, further comprising a differential pressure sensor (322) positioned above the filter (320). [7] The aftertreatment system (300) of claim 1, wherein the filter and reduction unit (318) further comprises: a static mixer (330) disposed within the housing (319) between the filter (320) and the selective catalytic reduction system (350). [8] A method for increasing a space available in the housing (319) of an aftertreatment system (300), the housing (319) defining an internal volume, the method comprising: Positioning a selective catalytic reduction system (350) in the internal volume defined by the housing (319); Positioning a filter (320) in the internal volume defined by the housing (319) upstream of the selective catalytic reduction system (350); fluidically coupling an inlet tube (302) to a housing inlet upstream thereof, the inlet tube (302) splitting into a first inlet tube (302a) connected to a first location of the housing (319) and a second inlet tube (302b) connected to a second location of the housing (319); Positioning a first catalyst (310) in each of the inlet pipes (302a, 302b); and fluidly coupling an exhaust pipe (380) to a housing outlet downstream thereof. [9] The method of claim 8, wherein the first catalyst (310) comprises a diesel oxidation catalyst. [10] The method of claim 8, further comprising: Positioning a differential pressure sensor (322) over the filter (320). [11] The method of claim 8, further comprising: Positioning a static mixer (330) upstream of the selective catalytic reduction system (350) and downstream of the filter (320). [12] The method of claim 8, further comprising: Positioning a second oxidation catalyst in the exhaust pipe (380). [13] The method of claim 12, wherein the second catalyst (370) comprises an ammonia oxidation catalyst.

Images