Engine Exhaust After-Treatment System

Abstract

An engine exhaust after-treatment system including an exhaust passage; an exhaust treatment component housing communicating with the exhaust passage; a pair of baffles spaced apart within the housing; a plurality of exhaust treatment devices positioned between the pair of baffles, each exhaust treatment device including a canister; a plurality of restraining devices fixed between the pair of baffles for positioning each of the canisters between the baffles, each restraining device including at least a portion thereof that is angled relative to an outer surface of the canister such that ends of the restraining device abut the outer surface of the canister at the first end and prevent radial movement of the canister; and a soot blower positioned in the housing upstream of the exhaust treatment devices, the soot blower for dispersing particulate matter deposited on each of the exhaust treatment devices.

Description

FIELD

The present disclosure relates to an engine exhaust after-treatment system.

BACKGROUND

This section provides background information related to the present disclosure which is not necessarily prior art.

Combustion engines are known to produce emissions that may be harmful to the environment. In an effort to decrease the environmental consequences that an engine may have, exhaust after-treatment systems have undergone extensive analysis and development. Various components that assist in treating engine emission include particulate filters and oxidation and reduction catalysts.

Over time, some of the various exhaust after-treatment elements may require removal and servicing. One way of accomplishing this is to make the various after-treatment components removable from the assembly, and then cleaned separately. Depending on the size of the engine application, however, the time and difficulty of this task can increase. In this regard, larger engine applications such as locomotive, marine, and large horsepower stationary applications can produce substantially more exhaust emissions than, for example, a tractor trailer engine application. The exhaust after-treatment systems, therefore, are generally much larger in scale to adequately treat emissions produced by these large-scale applications. As the scale of the after-treatment system increases, the ability to service such a system becomes substantially more difficult.

SUMMARY

This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

The present disclosure provides an engine exhaust after-treatment system including an exhaust passage; an exhaust treatment component housing communicating with the exhaust passage; a pair of baffles spaced apart within the housing; a plurality of exhaust treatment devices positioned between the pair of baffles, each exhaust treatment device including a canister; a plurality of restraining devices fixed between the pair of baffles for positioning each of the canisters between the baffles, each restraining device including at least a portion thereof that is angled relative to an outer surface of the canister such that ends of the restraining device abut the outer surface of the canister at the first end and prevent radial movement of the canister; and a soot blower positioned in the housing upstream of the exhaust treatment devices, the soot blower for dispersing particulate matter deposited on each of the exhaust treatment devices.

Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

FIG. 1 is a schematic representation of an exhaust system in accordance with a principle of the present disclosure;

FIG. 2 is a perspective view of an exhaust after-treatment system in accordance with a principle of the present disclosure;

FIG. 3 is an exploded perspective view of the exhaust after-treatment system illustrated in FIG. 2;

FIG. 4 is a partial exploded perspective view of an exhaust treatment component in accordance with a principle of the present disclosure;

FIG. 5 is a perspective view of a housing of an exhaust treatment component in accordance with a principle of the present disclosure;

FIG. 6 is a perspective view of an interior of the housing illustrated in FIG. 5 as viewed from an inlet side;

FIG. 7 is a perspective view of an interior of the housing illustrated in FIG. 5 as viewed from an outlet side;

FIG. 8 is a cross-sectional view taken along line 8-8 shown in FIG. 5; and

FIG. 9 is an enlarged cross-sectional view of one of the exhaust treatment components illustrated in FIG. 8.

Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference to the accompanying drawings.

FIG. 1 schematically illustrates an exhaust system 10 according to the present disclosure. Exhaust system 10 can include at least an engine 12 in communication with a pair of fuel source 14a and 14b that, once combusted, will produce exhaust gases that are discharged into an exhaust passage 16 having an exhaust after-treatment system 18. Fuel sources 14a and 14b may contain different fuels. For example, fuel source 14a can include a low sulfur diesel fuel (LSF), while fuel source 14b can include an ultra-low-sulfur diesel fuel (ULSF). Other exemplary fuels that can be used include marine gas oil (MGO), marine diesel oil (MDO), intermediate fuel oil (IFO), heavy fuel oil (HFO), combinations of natural gas and diesel fuel, or blends of natural gas with hydrogen. Further, it should be understood that any combination of the above-mentioned fuels can be stored in fuel sources 14a and 14b.

Downstream from engine 12 can be disposed an exhaust treatment component 20, which can include a diesel oxidation catalyst (DOC), a catalyst-coated diesel particulate filter (DPF) component or, as illustrated, a selective catalytic reduction (SCR) component 22. Although an SCR component 22 is illustrated, it should be understood that SCR component 22 can also include therein a DOC or a DPF. Further, SCR component 22 can be an SCR catalyst-coated DPF or an SCR catalyst-coated flow-through filter (FTF).

Exhaust after-treatment system 18 can further include components such as a thermal enhancement device or burner 24 to increase a temperature of the exhaust gases passing through exhaust passage 16. Increasing the temperature of the exhaust gas is favorable to achieve light-off of the catalyst in the exhaust treatment component 20 in cold-weather conditions and upon start-up of engine 12, as well as initiate regeneration of the exhaust treatment component 20 when the exhaust treatment component 20 is a DPF.

To assist in reduction of the emissions produced by engine 12, exhaust after-treatment system 18 can include a dosing module 26 for periodically dosing an exhaust treatment fluid into the exhaust stream. As illustrated in FIG. 1, dosing module 26 can be located upstream of exhaust treatment component 20, and is operable to inject an exhaust treatment fluid into the exhaust stream. In this regard, dosing module 26 is in fluid communication with a reagent tank 28 and a pump 30 by way of inlet line 32 to dose an exhaust treatment fluid such as diesel fuel, urea, or gaseous ammonia into the exhaust passage 16 upstream of exhaust treatment component 20. Tank 28 may store liquid exhaust treatment fluids, or may store solid or gaseous ammonia. Other materials that can be used to enhance exhaust treatment in combination with urea can be ethanol or hydrogen that may be stored in a separate tank (not shown).

Dosing module 26 can also be in communication with reagent tank 28 via return line 34. Return line 34 allows for any exhaust treatment fluid not dosed into the exhaust stream to be returned to reagent tank 28. Flow of the exhaust treatment fluid through inlet line 32, dosing module 26, and return line 34 also assists in cooling dosing module 26 so that dosing module 26 does not overheat. Although not illustrated in the drawings, dosing module 26 can be configured to include a cooling jacket that passes a coolant around dosing module 26 to cool it.

The amount of exhaust treatment fluid required to effectively treat the exhaust stream may vary with load, engine speed, exhaust gas temperature, exhaust gas flow, engine fuel injection timing, desired NO_x reduction, barometric pressure, relative humidity, EGR rate and engine coolant temperature. A NO_x sensor or meter 36 may be positioned downstream from SCR component 22. NO_x sensor 36 is operable to output a signal indicative of the exhaust NO_x content to an engine control unit (ECU) 38. All or some of the engine operating parameters may be supplied from ECU 38 via the engine/vehicle databus to an exhaust system controller 40. The exhaust system controller 40 could also be included as part of the ECU 38. Exhaust gas temperature, exhaust gas flow and exhaust back pressure and other vehicle operating parameters may be measured by respective sensors, as indicated in FIG. 1.

The amount of exhaust treatment fluid required to effectively treat the exhaust stream can also be dependent on the size of the engine 12. In this regard, large-scale diesel engines used in locomotives, marine applications, and stationary applications can have exhaust flow rates that exceed the capacity of a single dosing module 26. Accordingly, although only a single dosing module 26 is illustrated for urea dosing, it should be understood that multiple dosing modules 26 for urea injection are contemplated by the present disclosure.

During operation of engine 12, as noted above, the type of fuel provided to engine 12 can be switched between different fuel sources 14a and 14b. In the case where fuel sources 14a and 14b carry fuels with different sulfur contents, respectively, it should be understood that when engine 12 is using the fuel with higher sulfur content, after-treatment system 18 is not necessarily being utilized. That is, when engine 12 is a marine application where the vessel is located a predetermined distance from shore, emission regulations may not require use of after-treatment system 18. Accordingly, any exhaust produced by engine 12 while using a high-sulfur-content fuel (or any type of fuel) may be expelled into the atmosphere without passing through after-treatment system 18. To expel exhaust directly into the atmosphere before reaching after-treatment system 18, exhaust system 10 may include an after-treatment by-pass pipe 44.

A valve 48 may be positioned at an inlet of by-pass pipe 44 to allow exhaust gas to flow through by-pass pipe 44 or through after-treatment system 18. Valve 48 is in communication with controller 40 or ECU 38. If engine 12 is operating on a high-sulfur-content fuel, controller 40 or ECU 38 can instruct valve 48 to open by-pass pipe 44 and close exhaust passage 16 downstream of valve 48 to allow exhaust to escape into the atmosphere without passing through after-treatment system 18. Similarly, if engine 12 is being operated in an area where emission regulations require exhaust after-treatment, controller 40 or ECU 38 can instruct valve 48 to close by-pass pipe 44 to allow exhaust to pass through after-treatment system 18.

Fuel provided by fuel tanks 14a and 14b to engine 12 is controlled through valves 50a and 50b, respectively. Valves 50a and 50b are in communication with controller 40 and/or ECU 38. When it is desired to switch between fuels provided by tanks 14a and 14b, controller 40 or ECU 38 can instruct valves 50a and 50b to either open or close. For example, if engine 12 is switching to a lower-sulfur-containing fuel from a higher-sulfur-containing fuel, controller 40 or ECU 38 can instruct valve 50a to close and instruct valve 50b to open. Before controller 40 or ECU 38 sends instructions to valves 50a and 50b to either open or close, controller 40 or ECU 38 can instruct burner 24 to be activated to raise exhaust temperatures to an extent where any un-combusted fuel present in the exhaust stream can be combusted (e.g., 300 C). In this regard, if a fuel switch is desired, controller 40 or ECU 38 can signal instruct burner 24 to activate and delay actuation of valves 50a and 50b until burner 24 has operated for a predetermined period of time.

Although not required by the present disclosure, it should be understood that valve 48 can be controlled to open by-pass pipe 44 during the fuel switch while burner 24 is activated. When the fuel switch is complete and burner 24 is deactivated, valve 48 can close by-pass pipe 44 and allow the exhaust to pass through exhaust after-treatment system 18. In this manner, it can be ensured that any un-combusted high-sulfur-containing fuel can be prevented from reaching SCR component 22.

Moreover, valve 48 can be designed to be synchronized with fuel valves 50a and 50b. That is, if a signal is sent by controller 40 to fuel valve 50b to open such that engine 12 can operate on a lower-sulfur-containing fuel, valve 48 can simultaneously receive a signal to close by-pass pipe 44 to allow exhaust to travel through exhaust after-treatment system 18. Similarly, if a signal is sent by controller 40 to open fuel valve 50a such that engine 12 can operate on a higher-sulfur-containing fuel, valve 48 can simultaneously receive a signal to open by-pass pipe 44 to allow exhaust to be expelled into the atmosphere before passing through after-treatment system 18.

Now referring to FIGS. 2-9, an exemplary exhaust after-treatment system 18 in accordance with the present disclosure is illustrated. After-treatment system 18 includes exhaust passage 16 that provides exhaust produced by engine 12 to exhaust treatment component 20. A pair of mixing devices 52 can be disposed in exhaust passage 16 at a location between dosing module 26 and exhaust treatment component 20. Mixing devices 52 assist in dispersing and intermingling the exhaust treatment fluid dosed into the exhaust passage 16 with the exhaust produced by engine 12. Although a pair of mixing devices 52 are illustrated in FIGS. 2 and 3, it should be understood that a greater or fewer number of mixing devices 52 can be used without departing from the scope of the present disclosure. Exhaust after-treatment system 18 can be supported by a plurality of support structures 53.

An inlet 54 of bypass pipe 44 is located downstream from mixing devices 52. Valve 48 can be located at inlet 54 and operated to allow exhaust travelling in exhaust passage 16 to bypass exhaust treatment component 20. Although not illustrated in FIG. 1, it should be understood that another valve 56 can also be located at an exhaust treatment component inlet 58 so that when bypass pipe 44 is opened, fluid flow through exhaust treatment component 20 can be prevented by valve 56. In other words, if valve 48 is open, valve 56 is closed. Each of valves 48 and 56 can be, for example, butterfly-type valves actuated by a solenoid (not shown).

Bypass pipe 44 can be modular in design. For example, bypass pipe 44 can include a pair of curved sections 60a and 60b connected via a plurality of intermediate sections 62, 64, and 66. Although intermediate sections 62 and 66 are illustrated in FIGS. 2 and 3 as being cylindrically-shaped pipes, it should be understood that intermediate sections 62 and 66 can comprise flexible bellows that allow for thermal expansion during use of bypass pipe 44. Downstream from curved section 60b can be an outlet 68 that feeds the bypassed exhaust back into exhaust passage 16 at a position downstream from exhaust treatment component 20. Inlet 54 and outlet 68 of bypass pipe 44 can be integral or unitary with exhaust passage 16, or can be separately formed components similar to curved sections 60a and 60b and intermediate sections 62, 64, and 66.

Exhaust treatment component 20 can include a housing 70 that supports a plurality of SCR components 22. In the illustrated embodiment, housing 70 is box-shaped and includes a plurality of outer panels 71. Within outer panels 71 of housing 70 may be disposed a plurality of trusses 73. Trusses 73 can be L-shaped members that are positioned at corners of outer panels 71 within an interior of housing 70. Trusses 73 provide structural support to housing 70, and allow housing 70 to support each of SCR components 22. Between trusses 73 can also be positioned cross-members 75. Similar to trusses 73, cross-members 75 provide structural support to housing 70.

Housing 70 supports an array of nine SCR components 22. Although nine SCR components 22 are illustrated in the figures, it should be understood that any number of SCR components 22 can be supported within housing 70 without departing from the scope of the present disclosure. SCR components 22 may be cylindrically-shaped, although any configuration for SCR components 22 is contemplated.

Housing 70 can be disposed between an inlet cone 72 and an outlet cone 74. Inlet cone 72 includes a flange 76 that corresponds and bolts to flange 78 of housing 70. Outlet cone 74 can include a flange 80 that corresponds and bolts to another flange 82 of housing 70. Such a configuration results in rigid and hermetically-sealed exhaust treatment component 20.

As best shown in FIG. 5, housing 70 can include an inlet side 84 and an outlet side 86. At inlet side 86 can be positioned a particulate matter dispersion device 88 (hereinafter “soot blower”). Soot blower 88 is designed and operable to eject compressed air towards SCR components 22 to disperse any deposits of particulate matter that may build up on SCR components 22. Soot blower 88 includes a plurality of arrays 90 of nozzle lines 92, with each nozzle line 92 including a plurality of nozzles 94 for ejecting compressed air towards exhaust SCR components 22. Nozzle lines 92 can be formed of various metal materials including aluminum, steel, copper, or any other material known to one skilled in the art. Housing 70 can include a plurality of apertures (not shown) that allow nozzle lines 92 to pass therethrough. To secure nozzle lines 92 at apertures, a seat member 98 and gasket 100 can be used.

Although dispersing particulate matter and/or soot at the face of the SCR components 22 is desirable and preferred, it should be understood that the present disclosure should not be limited thereto. In contrast, it should be understood that the present disclosure also provides a soot blower 88 that is designed to prevent the build-up of particulate matter and/or soot at locations other than the SCR component 22 face. More particularly, particulate matter and/or soot can build up at locations other than the SCR component 22 face. If too much particulate matter and/or soot builds up at these “dead spots” between SCR components 22, the built-up particulate matter and/or soot can eventually break off and plug the SCR components 22. Accordingly, it should be understood that nozzles 94 can be positioned to eject compressed air at positions between SCR components 22 without departing from the scope of the present disclosure.

Now referring to FIGS. 4, 6, and 7-9, an exhaust treatment component mounting system according to the present disclosure will be described. Housing 70 can include a pair of baffles 102a and 102b to support each SCR component 22. Baffles 102a and 102b can be welded to inner surfaces 104 of housing 70 and include a plurality of through-holes 106 (FIG. 9) sized to receive SCR components 22. Each SCR component 22 includes a canister 108 that houses a SCR substrate 110. Between canister 108 and SCR substrate 110 can be disposed an insulating mat 112.

To secure canisters 108 between baffles 102a and 102b, a plurality of restraining devices 114 can be used. Restraining devices 114 can be a linear (e.g., planar) member that is welded between baffles 102a and 102b. Alternatively, restraining devices 114 can be L-shaped in cross-section (FIG. 7). Regardless, as best illustrated in FIG. 9, at least a portion of restraining devices 114 are positioned at an angle α relative to a surface 116 of canister 108 that runs parallel with an axis A of SCR component 22. Angle a may be in the range of 1 to 20 degrees, inclusive. Preferably, angle α is in the range of 5 to 15 degrees, inclusive. Most preferably, angle α is in the range of 5 to 10 degrees, inclusive.

Due to at least a portion of restraining device 114 being angled relative to surface 116, restraining device 114 will abut canister 108 at a first end 118 as SCR component 22 is inserted into housing 70. Once restraining device 114 abuts canister 108, radial movement of SCR component 22 is prevented. FIGS. 7 and 9 illustrate the abutment between restraining device 114 and canister 108. Moreover, the abutment between restraining devices 114 and canister 108 assists in positioning the canister between baffles 102a and 102b during insertion of canisters into housing 70.

After canister 108 abuts restraining device 114, a second end 120 of canister 108 can be secured by bolting ear members 122. Ear members 122 can be separately-formed members that are welded to second end 120 of canister 108. Alternatively, canister 108 can be provided with a radially extending flange (not shown) at second end 120. Regardless, ear member 122 is operable to receive a fastener 124 that bolts ear member 122 and canister 108 to baffle 102b. As best shown in FIGS. 4-6, four restraining devices 114 (as represented by ears 122) can be used to secure canister 108 between baffles 102a and 102b. It should be understood, however, that a greater or lesser number of restraining devices 114 can be used without departing from the scope of the present disclosure.

Because restraining devices 114 secure first end 118 of canister 108, it is unnecessary to bolt first end 118 of canister 108 to baffle 102a. The ease with which canisters 108 can be inserted and removed from housing 70 can be increased. More particularly, if any of SCR components 22 require servicing, only fasteners 124 need to be removed to withdraw SCR components 122 from housing 70. This greatly reduces service time in comparison to a configuration where SCR components 22 are bolted in first and second ends 118 and 120, or welded to baffles 102a and 102b. To assist in removing SCR components 22 from housing 70, ear members 122 can include an aperture 123 that may receive a tool (not shown) to assist an operator in pulling SCR component 22 from housing 70.

The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Claims

1. An exhaust after-treatment component, comprising: a housing;a pair of baffles spaced apart within the housing;a canister including an exhaust treatment substrate positioned between the pair of baffles, the canister including a first end and a second end; anda plurality of restraining devices fixed between the pair of baffles for positioning the canister between the baffles, each restraining device including a first portion spaced apart from an outer surface of the canister and a second portion abutting the outer surface of the canister at the first end and preventing radial movement of the canister.

2. The exhaust treatment component of claim 1, wherein a second end of the canister is bolted to one of the baffles.

3. The exhaust treatment component of claim 1, wherein the exhaust treatment substrate is an SCR substrate.

4. The exhaust treatment component of claim 1, further comprising a particulate matter dispersion device within the housing.

5. The exhaust treatment component of claim 4, wherein the particulate matter dispersion device includes a plurality of nozzle lines, each nozzle line including a plurality of nozzles for dispersing particulate matter deposited on the exhaust treatment substrate.

6. The exhaust treatment component of claim 1, wherein a plurality of canisters are supported between the baffles in an array.

7. The exhaust treatment component of claim 6, wherein each canister corresponds to a plurality of restraining devices that position the canisters between the baffles.

8. The exhaust treatment component of claim 1, wherein the restraining devices abut the canister at an inlet side of the housing.

9. The exhaust treatment component of claim 1, wherein the first portion of the restraining device forms an angle α relative to the outer surface of the canister in the range of 1 to 20 degrees, inclusive.

10. The exhaust treatment component of claim 9, wherein α is in the range of 5 to 15 degrees, inclusive.

11. The exhaust treatment component of claim 10, wherein α is in the range of 5 to 10 degrees, inclusive.

12. An engine exhaust after-treatment system, comprising: an exhaust passage;an exhaust treatment component housing communicating with the exhaust passage;a pair of baffles spaced apart within the housing;a plurality of exhaust treatment devices positioned between the pair of baffles, each exhaust treatment device including a canister;a plurality of restraining devices fixed between the pair of baffles for positioning each of the canisters between the baffles, each restraining device including a first portion spaced apart from an outer surface of the canister and a second portion engaging the outer surface of the canister to prevent radial movement of the canister; anda soot blower positioned in the housing upstream of the exhaust treatment devices, the soot blower for dispersing particulate matter deposited on each of the exhaust treatment devices.

13. The exhaust after-treatment system of claim 12, wherein a second end of the canisters is bolted to one of the baffles.

14. The exhaust after-treatment system of claim 12, wherein the exhaust treatment devices each include an SCR substrate.

15. The exhaust after-treatment system of claim 12, wherein the soot blower includes a plurality of nozzle lines, each nozzle line including a plurality of nozzles.

16. The exhaust after-treatment system of claim 12, wherein the restraining devices abut the canisters at an inlet side of the housing.

17. The exhaust after-treatment system of claim 12, wherein the first portion of the restraining device forms an angle α relative to the outer surface of the canister in the range of 1 to 20 degrees, inclusive.

18. The exhaust after-treatment system of claim 12, further comprising a bypass pipe that directs exhaust gases around the exhaust treatment component housing.

19. The exhaust after-treatment system of claim 18, wherein a first valve is disposed within the bypass pipe, and a second valve is positioned at an inlet of exhaust treatment component housing.

20. The exhaust treatment component system of claim 19, wherein when the first valve is open, the second valve is closed.