U.S. patent application number 12/573469 was filed with the patent office on 2011-04-07 for reductant nozzle indentation mount.
This patent application is currently assigned to Caterpillar Inc.. Invention is credited to Paul F. Olsen, Stephan D. Roozenboom, Jinhui Sun.
Application Number | 20110079003 12/573469 |
Document ID | / |
Family ID | 43822111 |
Filed Date | 2011-04-07 |
United States Patent
Application |
20110079003 |
Kind Code |
A1 |
Sun; Jinhui ; et
al. |
April 7, 2011 |
REDUCTANT NOZZLE INDENTATION MOUNT
Abstract
An engine exhaust aftertreatment system including a bend routing
an exhaust flow in a curved direction to a straight part. A nozzle
is mounted in the bend to introduce a spray of a fluid with a axis
of symmetry into the exhaust flow. The axis of symmetry intersects
the exhaust flow traveling in the curved direction at a
intersection angle of less than 50 degrees.
Inventors: |
Sun; Jinhui; (Bloomington,
IL) ; Olsen; Paul F.; (Chillicothe, IL) ;
Roozenboom; Stephan D.; (Washington, IL) |
Assignee: |
Caterpillar Inc.
Peoria
IL
|
Family ID: |
43822111 |
Appl. No.: |
12/573469 |
Filed: |
October 5, 2009 |
Current U.S.
Class: |
60/310 ;
60/324 |
Current CPC
Class: |
F01N 2610/1453 20130101;
F01N 3/2066 20130101; Y02T 10/12 20130101; Y02T 10/24 20130101 |
Class at
Publication: |
60/310 ;
60/324 |
International
Class: |
F01N 3/04 20060101
F01N003/04; F01N 13/00 20100101 F01N013/00 |
Claims
1. An engine exhaust aftertreatment system comprising: a bend
routing an exhaust flow in a curved direction; a straight part
receiving the exhaust flow from the bend; and a nozzle mounted in
the bend to introduce a spray of a fluid with a axis of symmetry
into the exhaust flow wherein the axis of symmetry intersects the
exhaust flow traveling in the curved direction at a intersection
angle between the axis of symmetry and the exhaust flow of less
than 50 degrees.
2. The engine exhaust aftertreatment system of claim 1 further
including an indentation in the bend wherein the nozzle is mounted
in the indentation.
3. The engine exhaust aftertreatment system of claim 2 wherein the
indentation extends into more than 10% of a depth of the bend.
4. The engine exhaust aftertreatment system of claim 2 wherein the
indentation includes an upstream wall with a upstream wall length
of at least 10% of a depth of a bend inlet.
5. The engine exhaust aftertreatment system of claim 4 wherein the
indentation includes a downstream wall with a downstream wall
length of at least 10% of a depth of a bend outlet.
6. The engine exhaust aftertreatment system of claim 5 wherein the
nozzle is mounted in the downstream wall.
7. The engine exhaust aftertreatment system of claim 6 wherein the
nozzle is located to align the axis of symmetry of the spray with a
central axis of the exhaust flow in the straight part.
8. The engine exhaust aftertreatment system of claim 6 wherein the
upstream wall length is at least 50% of a depth of a bend inlet and
the downstream wall length is at least 50% of a depth of a bend
outlet.
9. The engine exhaust aftertreatment system of claim 1 wherein the
indentation has a triangular shape.
10. The engine exhaust aftertreatment system of claim 1 wherein the
intersection angle is less than 40 degrees.
11. The engine exhaust aftertreatment system of claim 1 wherein the
intersection angle is approximately 30 degrees.
12. The engine exhaust aftertreatment system of claim 1 further
including a selective catalytic reduction system and the fluid is a
urea reductant.
13. An engine exhaust aftertreatment system comprising: a bend
routing an exhaust flow in a curved direction; a straight part
receiving the exhaust flow from the bend; an indentation extending
into more than 10% of a depth of the bend; and a nozzle mounted in
the indentation to introduce a spray of a fluid into the exhaust
flow.
14. The engine exhaust aftertreatment system of claim 13 wherein
the indentation includes an upstream wall with a upstream wall
length of at least 10% of a depth of a bend inlet.
15. The engine exhaust aftertreatment system of claim 14 wherein
the indentation includes a downstream wall with a downstream wall
length of at least 10% of a depth of a bend outlet and the nozzle
is mounted in the downstream wall.
16. The engine exhaust aftertreatment system of claim 13 wherein
the indentation extends into more than 30% of a depth of the
bend.
17. The engine exhaust aftertreatment system of claim 13 wherein
the indentation extends into approximately 50% of a depth of the
bend.
18. An engine exhaust aftertreatment system comprising: a bend
routing an exhaust flow in a curved direction; a straight part
receiving the exhaust flow from the bend; an indentation including
an upstream wall with a upstream wall length of at least 10% of a
depth of a bend inlet; and a nozzle mounted in the indentation to
introduce a spray of a fluid into the exhaust flow
19. The engine exhaust aftertreatment system of claim 18 wherein
the upstream wall length is at least 40% of a depth of a bend
inlet.
20. The engine exhaust aftertreatment system of claim 18 wherein
the upstream wall length is approximately 70% of a depth of a bend
inlet.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to injecting a reductant in
an engine exhaust aftertreatment system, and more particularly to
mounting and locating a nozzle to inject the reductant.
BACKGROUND
[0002] A selective catalytic reduction (SCR) system may be included
in an exhaust treatment or aftertreatment system to remove or
reduce nitrous oxide (NOx or NO) emissions coming from the exhaust
of an engine. SCR systems use reductants, such as urea. These
reductants may form deposits in the aftertreatment system.
[0003] PCT Patent Application Publication WO 2009071088 (the '088
publn) discloses aligning an axis of spray from a nozzle injecting
reductant with an axis of symmetry of a straight part of an exhaust
pipe. The '088 publn, however, may not locate the nozzle in a
desired location.
SUMMARY
[0004] In one aspect, the present disclosure provides an engine
exhaust aftertreatment system including a bend routing an exhaust
flow in a curved direction to a straight part. A nozzle is mounted
in the bend to introduce a spray of a fluid with a axis of symmetry
into the exhaust flow. The axis of symmetry intersects the exhaust
flow traveling in the curved direction at an intersection angle
between the axis of symmetry and the exhaust flow of less than 50
degrees.
[0005] In another aspect the present disclosure provides an engine
exhaust aftertreatment system wherein the indentation extends into
more than 10% of a depth of the bend. In yet another aspect, the
indentation includes an upstream wall with an upstream wall length
of at least 10% of a depth of a bend inlet.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a diagrammatic view of an aftertreatment
system.
[0007] FIG. 2 is a diagrammatic view of a bend of the
aftertreatment system from FIG. 1.
[0008] FIG. 3 is a cross-sectional view of the bend from FIG.
2.
[0009] FIG. 4 is a cross-sectional view of the bend from FIG. 2
showing an exhaust flow and a spray of reductant.
[0010] FIG. 5 is a cross-sectional view of a bend and straight part
from FIG. 1 showing the distribution of a spray of reductant as it
passes down the straight part.
[0011] FIG. 6 is a cross-sectional view of a bend and straight part
from FIG. 1 showing the distribution of a spray of reductant as it
passes down the straight part and through a mixer.
[0012] FIG. 7 is a cross-sectional view of the bend from FIG. 2
showing the nozzle mounted at an angle.
DETAILED DESCRIPTION
[0013] The aftertreatment system 10 seen in FIG. 1, receives an
exhaust flow 12 from an engine or power system. The engine may be
any type of engine (internal combustion, gas, diesel, gaseous fuel,
natural gas, propane, etc.), may be of any size, with any number of
cylinders, and in any configuration ("V," in-line, radial, etc.).
The engine may be used to power any machine or other device,
including on-highway trucks or vehicles, off-highway trucks or
machines, earth moving equipment, generators, aerospace
applications, locomotive applications, marine applications, pumps,
stationary equipment, or other engine powered applications.
[0014] The aftertreatment system 10 includes an SCR catalyst 14 and
a reductant system 16. The SCR catalyst 14 includes a catalyst
material disposed on a substrate. The catalyst material is
configured to reduce an amount of NOx in the exhaust flow 12 by
using a reductant 19. The substrate may consist of cordierite,
silicon carbide, other ceramic, or metal. The substrate may include
a plurality of through going channels and may form a honeycomb
structure. An ammonia oxidation catalyst (AMOX) may also be
included downstream of the SCR 14 or zone coated on the end of the
SCR 14.
[0015] The reductant system 16 includes an injector or nozzle 18
that introduces a reductant 19 into the exhaust flow 12. The nozzle
18 may include springs, washers, cooling passages, injector pins,
and other features not shown.
[0016] While other reductants 19 are possible, urea is the most
common source of reductant 19. Urea reductant 19 decomposes into
ammonia (NH3) and is then adsorbed or stored in the SCR catalyst
14.
[0017] The exhaust flow 12 is introduced to the SCR catalyst 14 via
an exhaust pipe 20. The exhaust pipe 20 includes a straight part 22
and a curved part or bend 24 upstream from the straight part 22.
The nozzle 18 is mounted in the bend 24. The length of the straight
part 22 or distance between the nozzle 18 and SCR catalyst 14 may
be sufficiently long to achieve the mixing of reductant 19 into the
exhaust flow 12 and provide the dwell time for the urea reductant
19 to convert into NH3.
[0018] The aftertreatment system 10 may also include a diesel
oxidation catalyst (DOC) 26, a diesel particulate filter (DPF) 28,
and a clean up catalyst or other exhaust treatment devices upstream
or downstream of the SCR catalyst 14. The currently illustrated
aftertreatment system 10 shows the DOC 26 upstream of the DPF 28,
which is upstream of the SCR catalyst 14.
[0019] The aftertreatment system 10 may also include a heat source
30 to regenerate the DPF 28. The heat source 30 may embody a burner
including a combustion head and a housing to contain a flame. The
heat source 30 may also embody an electric heating element,
microwave device, or other heat source. Heat may also be created by
injecting a hydrocarbon source, such as fuel, in to the exhaust
flow 12 that will exothermically react in the DOC 26. The heat
source 30 may also embody operating the engine under conditions to
generate elevated exhaust flow 12 temperatures.
[0020] The DOC 26 and DPF 28 may be housed in a common first
canister 32. The DOC 26 and DPF 28 may also be housed in separate
canisters. The SCR catalyst 14 may be housed in a second canister
34. The heat source 30, first canister 32, and second canister 34
may be arranged in side-by-side parallel orientation on a mount 36.
The heat source 30, first canister 32, and second canister 34 may
also be arranged and mounted in other ways.
[0021] The exhaust pipe 20 may also include second bend 38
downstream of the straight part 22 for routing the exhaust flow 12
into the second canister 34. In other embodiments, this second bend
38 may not be included and the second canister 34 may be aligned
with the straight part 22. The first and second canisters 32 and 34
may also include ends 40 for delivering and receiving the exhaust
flow 12.
[0022] An entering pipe 42 routes the exhaust flow 12 to the
aftertreatment system 10. The second canister 34, or another end
canister, may include an exit port 44 for the exhaust flow 12 to
exit the aftertreatment system 10.
[0023] An additional section of exhaust pipe (not shown) may route
the exhaust flow 12 from the heat source 30 to the first canister
32 receiving end 40. In other embodiments, the heat source 30 may
not be included and the entering pipe 42 may route the exhaust flow
12 to the first canister 32 receiving end 40.
[0024] The exhaust flow 12 passes through the entering pipe 42 and
next through the heat source 30, if included, in a first direction
46. Next, the exhaust flow 12 is routed to pass through the first
canister 32 in a second direction 48 that may be parallel to the
first direction 46. The exhaust flow 12 passes through the DOC 26,
DPF 28, end 40, and through the bend 24. Next the exhaust flow 12
passes through the straight part 22 in a third direction 50 that
may be parallel to the second direction 48. Next, the exhaust flow
12 is routed to pass through the second bend 38 and through the
second canister 34 in a fourth direction 52 that may be parallel to
the second direction 48. Finally the exhaust flow 12 exits through
the exit port 44.
[0025] The reductant system 16 may also include a reductant source
54, pump 56, and valve 57. The reductant 19 is drawn from the
reductant source 54 via the pump 56 and delivered to an inlet
connection 58 on the nozzle 18. The valve 57 or pump 56 may be used
to control the delivery of the reductant 19. A controller and
sensors may also be included to control the reductant system 16.
The controller and sensors may also control the heat source 30. The
controller may also be in communication with an engine control
module (ECM) or may be included in the ECM.
[0026] The reductant system 16 may also include a coolant source 60
that delivers coolant 62 to the nozzle 18 via coolant ports
connections 64. The coolant source 60 may embody the engine's
coolant system or another coolant source 60. The coolant 62 may
also be used to cool other parts of the reductant system 16 or
aftertreatment system 10. The coolant 62 may also be used to thaw
frozen urea 19.
[0027] Seen best in FIG. 4, the nozzle 18 includes a tip or outlet
66. A spray 68 of reductant 19 is introduced in the exhaust flow 12
from the outlet 66. The spray 68 defines an axis of symmetry 70.
Absent any influence by the exhaust flow 12, the axis of symmetry
70 may be substantially parallel to the third direction 50.
[0028] Seen best in FIG. 2, the bend 24 includes a bend inlet end
72, bend outlet end 74, bend outer curve 76, bend inner curve 78,
and bend sides 80. The bend outer curve 76, bend inner curve 78,
and bend sides 80 form a bent tube or box structure with an open
bend inlet end 72 and bend outlet end 74. The bend inlet end 72
joins to and is in fluid communication with the end 40 of first
canister 32. The bend outlet end 74 joins to and is in fluid
communication with the straight part 22.
[0029] The bend outer curve 76, bend inner curve 78, and bend sides
80 discussed above represent walls exposed to the exhaust flow 12.
As seen in FIGS. 3 and 4, bend 24 may also include double walls 82
outside of these walls. The double walls 82 provide thermal
protection from the exhaust flow 12.
[0030] An indentation 84 is included in the bend outer curve 76.
The indentation 84 is defined by or includes an indentation
downstream wall 86, indentation upstream wall 88, and sidewalls 90.
The indentation downstream wall 86, indentation upstream wall 88,
and sidewalls 90 form a recessed pocket or area in the bend 24. The
indentation 84 may have rounded triangular shape with a width at
the upstream end greater than a width at the downstream end. The
indentation 84 may also have other shapes, including rectangular,
cylindrical, or hemispherical.
[0031] The straight part 22 includes an upstream end 92, downstream
end 94, outer wall 96, inner wall 98, and sides 100 to form a
tubular pipe. Straight part 22, and other components, may be
wrapped in insulation 102. The upstream end 92 joins to the bend
outlet end 74.
[0032] Dimensional aspects of the bend 24 and indentation 84 are
seen best FIGS. 2 and 3. FIG. 2 shows the bend 24 has an inlet
width 101 and an outlet width 103. The width of the bend 24 may
decrease from the bend inlet end 72 to bend outlet end 74 resulting
in a smaller outlet width 103 than inlet width 101.
[0033] As seen in FIG. 3, the bend 24 has an inlet depth 104 and an
outlet depth 106. The depth of the bend 24 may increase gradually
from the bend inlet end 72 to bend outlet end 74 resulting in a
larger outlet depth 106 than inlet depth 104. Because the relative
sizes of the inlet width 101 to outlet width 103 and inlet depth
104 to outlet depth 106 vary in opposite relation, a substantially
constant flow area may be maintained.
[0034] In other embodiments, the width and depth of bend 24 may be
constant or vary differently. The outlet depth 106 and outlet width
103 may substantially match the width or diameter of the straight
part 22.
[0035] A centerline 108, shown in FIG. 3, extends through the
center of the bend 24 and may continue through the straight part
22. The indentation 84 extends into the bend 24 and includes a
maximum bend extension point 110. The maximum bend extension point
110 may be a point or line where the indentation downstream wall 86
and indentation upstream wall 88 meet. A bend central plane 112
extends through the maximum bend extension point 110 and is normal
to the centerline 108. A projected outer curve 114 extends in space
over the indentation 84 along the same curvature as the bend outer
curve 76.
[0036] A projected center depth 116 represents a central depth of
the bend 24 if the indentation 84 did not exist. This projected
center depth 116 is the depth of the bend 24 along the bend central
plane 112 from the inner curve 78, through the maximum bend
extension point 110 to the projected outer curve 114.
[0037] A minimum center depth 118 represents a central depth of the
bend 24 where it is the smallest because of the indentation 84.
This minimum center depth 118 is the depth of the bend 24 along the
bend central plane 112 from the bend inner curve 78 to the maximum
bend extension point 110.
[0038] An indentation maximum extension length 120 represents the
maximum depth of the indentation 84. This indentation maximum
extension length 120 is the length along the bend central plane 112
from the maximum bend extension point 110 to the projected outer
curve 114.
[0039] The indentation 84 has a downstream wall length 122 and
upstream wall length 124. The downstream wall length 122 is the
length extending along the downstream wall 86 from the outer curve
76 to the maximum bend extension point 110. The upstream wall
length 124 is the length extending along the upstream wall 88 from
the outer curve 76 to the maximum bend extension point 110.
Although many of the dimensions above are referred to as minimums
and maximums, projections and other additional structures should
not be considered as included in these dimensions.
[0040] FIG. 4 shows the directions of flow of the exhaust flow 12
as it travels through the bend 24 into the straight part 22. The
directions of flow include a straight inlet direction 126, straight
outlet direction 128, and a central curved direction 130 between
the straight inlet direction 126 and straight outlet direction 128.
Also included are blocked flows 132 under the upstream wall 88 of
the indentation 84. Dead flows 134 also exist downstream of the
downstream wall 86 and in the corner where the downstream wall 86
at outer curve 76 meet.
[0041] The nozzle 18 may be mounted in the downstream wall 86 to
position the outlet 66 and axis of symmetry 70 to align with the
centerline 108 as it extends in the straight part 22.
[0042] The indentation 84 is also sized to locate the axis of
symmetry 70 to intersect with an intermediate direction 136 of the
exhaust flow 12. The intermediate direction 136 is the direction of
exhaust flow 12 as it begins to straighten into the straight outlet
direction 128 from the central curved direction 130. The
intermediate direction 136 is the first exhaust flow 12 to
intersect the axis of symmetry 70 that is not blocked by the
upstream wall 88.
[0043] The axis of symmetry 70 intersects the exhaust flow 12
traveling in the intermediate direction 136 at an intersection
angle 138 of approximately 30 degrees. In certain embodiments the
intersection angle 138 is less than 50, 45, 40, 35, 35, 30, 25, 20,
15, 10, or 5 degrees. In other embodiments the intersection angle
138 is between 5 and 50 degrees, 5 and 35 degrees, 5 and 25
degrees, 20 and 40 degrees, or 20 and 50 degrees. In yet other
embodiments the axis of symmetry 70 may intersect the exhaust flow
12 traveling in the straight outlet direction 128 and the
intersection angle 138 may be substantially zero.
[0044] The intersection angle 138 is achieved by the location and
size of the indentation 84 relative to the bend 24. The percentage
of indentation maximum extension length 120 compared to the
projected center depth 116 represents the degree to which the
indentation 84 extends into the depth of the bend 24. The
indentation maximum extension length 120 may be approximately 50%
of the projected center depth 116. In certain embodiments, the
indentation maximum extension length 120 may be at least 60%, 40%,
30%, 20%, or 10% of the projected center depth 116. In other
embodiments, the indentation maximum extension length 120 may be
between 10% and 80%, 30% and 70%, 40% and 60%, 30% and 60%, or 40%
and 70% of the projected center depth 116.
[0045] The upstream wall 88 blocks the exhaust flow 12, requiring a
long upstream wall length 124 to achieve the intersection angle
138. The upstream wall length 124 may be approximately 70% of the
bend inlet depth 104. In certain embodiments, however, the upstream
wall length 124 may be at least 80%, 70%, 60%, 50%, 40%, 30%, 20%,
or 10% of the bend inlet depth 104. In other embodiments the
upstream wall length 124 may be between 10% and 90%, 30% and 90%,
50% and 90%, 40% and 90%, or 40% and 80% of the bend inlet depth
104.
[0046] The downstream wall 86 locates the nozzle 18 and connects to
the upstream wall 88, thereby requiring a long downstream wall
length 122 to achieve the intersection angle 138 and nozzle 18
position. The downstream wall length 122 may be approximately 70%
of the bend outlet depth 106. In certain embodiments, however, the
downstream wall length 122 may be at least 80%, 70%, 60%, 50%, 40%,
30%, 20%, or 10% of the bend outlet depth 106. In other embodiments
the downstream wall length 122 may be between 10% and 90%, 30% and
90%, 50% and 90%, 30% and 80%, or 30% and 70% of the bend outlet
depth 106.
[0047] The downstream wall length 122 may also provide a flat
mounting surface 140 for mounting the nozzle 18. The size or depth
of the indentation 84 and downstream wall length 122 and upstream
wall length 124 also provides a recessed area for the nozzle to be
located. This recessed area may help protect the nozzle 18 and its
connections 58, 64.
[0048] Backpressure concerns may limit the size of the indentation
84. These concerns may be at least partially addressed by the shape
whereby the indentation 84 narrows as it goes deeper into the bend
24. Backpressure concerns may also be addressed by the ratio of
inlet and outlet widths 101 and 103 to an indentation width 143 of
the indentation 84. The indentation width 143 may be approximately
20% of the bend inlet width 101. In certain embodiments, however,
the indentation width 143 may be at least 80%, 70%, 60%, 50%, 40%,
30%, 20%, or 10% of the bend inlet width 101. In other embodiments
the indentation width 143 may be between 5% and 90%, 5% and 60%, 5%
and 40%, 10% and 30%, or 20% and 40% of the bend inlet width 101.
The indentation width 143 may be approximately 40% of the bend
outlet width 103. In certain embodiments, however, the indentation
width 143 may be at least 80%, 70%, 60%, 50%, 40%, 30%, 20%, or 10%
of the bend outlet width 103. In other embodiments the indentation
width 143 may be between 5% and 90%, 5% and 70%, 10% and 60%, 20%
and 70%, or 20% and 50% of the bend outlet width 103
[0049] Other embodiments may utilize a longer nozzle 18 that
extends into the exhaust flow 12 to achieve the intersection angle
138. This design however may cause the reductant 19 to overheat and
crystallize inside the nozzle 18 as it is now exposed to the hot
exhaust flow 12. This embodiment also fails to protect the portion
of the nozzle 18 outside the bend 24. This embodiment may also fail
to provide a flat mounting surface 140.
[0050] FIG. 5 illustrates the flow of droplets 142 as they are
injected from nozzle 18 as a spray 68, intersect with the exhaust
flow 12, and travel down the straight part 22. Because of the low
intersection angle 138, less of an outward force from the exhaust
flow 12 is exerted on the spray 68. Accordingly, the droplets 142
may tend towards (because some outward force may still exists), but
not impact in a significant way on the outer wall 96. The low
intersection angle 138 helps project the droplets down the straight
part 22 in a straighter direction than with a higher intersection
angle 138 or a smaller indention 84 because the outward force
vector exerted by the exhaust flow 12 traveling in the curved
direction 130 on the reductant spray 68 is reduced.
[0051] FIG. 6 illustrates an embodiment including a mixer 144. As
seen, the mixer 144 helps distribute and mix the droplets 142 with
the exhaust flow 12. The mixer 144 also helps prevent the droplets
142 from impacting the outer wall 96 by locating the mixer 144 in
the straight part 22 before the droplets 142 have significantly
tended towards the outer wall 96. Mixing plates, mixing vanes, and
baffles may also be added in the straight part 22 or bend 24.
[0052] An alternative embodiment is shown in FIG. 7 with the nozzle
18 disposed at a mount angle 150. Because of the mount angle 150,
the axis of symmetry 70 is directed toward the inner wall 98, which
helps counteract the outward force of the exhaust flow 12 traveling
in the central curved direction 130. The mount angle 150 may be
defined as the angle between a nozzle plane 152 and a normal plane
154. The nozzle plane 152 is defined normal to the outlet 66 or
front face of the nozzle 18 so that the axis of symmetry 70 will be
normal to the nozzle plane 152. The normal plane 154 is defined as
perpendicular to the straight outlet direction 128 and may also be
parallel to the straight inlet direction 126.
[0053] The magnitude of the desired mount angle 150 may depend on
the degree of the outward force of the exhaust flow 12 traveling in
the central curved direction 130. This outward force will depend on
the geometries of the bend 24 and indentation 84. The outward force
will also change during engine operation as the mass flow of the
exhaust flow 12 changes. The mount angle must be large enough to
have a meaningful impact but small enough to avoid reductant 19
from impacting and forming deposits on the inner wall 98 during low
exhaust flows 12. The mount angle 150 may be approximately 15
degrees. In certain embodiments the mount angle is greater than
zero but less than 50, 45, 40, 35, 35, 30, 25, 20, 15, 10, or 5
degrees. In other embodiments the mount angle 150 is between 10 and
30 degrees, 10 and 20 degrees, 20 and 30 degrees, 5 and 20 degrees,
or 30 and 50 degrees.
[0054] FIG. 7 also shows that the nozzle 18 may be moved on the
downstream wall 86 to be closer to the inner wall 98 than the outer
wall 96 to avoid reductant 19 from impacting and forming deposits
on the inner wall 98. The mount angle 150 may be formed by tilting
the upstream wall 88. FIG. 7 also shows that a curve 156 may be
added to the upstream wall 88 so that the length of the upstream
wall 88 can be maintained.
[0055] The mount angle 150 may create a larger intersection angle
138. In such embodiments, the intersection angle may be
approximately 45 degrees. In certain such embodiments the mount
angle 150 may result in the intersection angle 138 being as high as
90, 80, 70, 60, 50, 40, or 30 degrees is less than 50, 45, 40, 35,
35, 30, 25, 20, 15, 10, or 5 degrees. In other such embodiments the
mount angle 150 may result in the intersection angle 138 being
between 10 and 90 degrees, 30 and 90 degrees, 40 and 80 degrees, 40
and 60 degrees, or 50 and 80 degrees.
INDUSTRIAL APPLICABILITY
[0056] Reductant sprays 68 often form deposits in the
aftertreatment system 10. The deposits may form under a number of
different conditions and through a number of different mechanisms.
Deposits may form when the urea reductant 19 is not quickly
decomposed into NH3 and thick layers of urea reductant 19 collect.
These layers may build as more and more urea reductant 19 is
sprayed or collected, which may have a cooling effect that prevents
decomposition into NH3. As a result, the urea reductant 19
sublimates into crystals or otherwise transforms into a solid
composition to form the deposit. This composition may consist of
biuret (NH2CONHCONH2) or cyanuric acid ((NHCO)3) or another
composition depending on temperatures and other conditions.
[0057] While the reductant system 16 may or may not be
air-assisted, deposits more readily develop in airless reductant
systems 16. Airless reductant systems 16 tend to produce reductant
sprays 68 with larger droplet sizes than air-assisted reductant
systems 16. The larger droplet size in the reductant spray 68 may
cause deposit formations. In general, these deposits may form on
surfaces of the aftertreatment system 10 where the reductant spray
68 impinges, recirculates, or settles. For example, the deposits
may form on the outer wall 96 or around the outlet 66.
[0058] These deposits may have negative impacts on the operation of
the power system. The deposits may block the exhaust flow 12,
causing higher back-pressure and reducing engine and aftertreatment
system 10 performance and efficiency. The deposits may also disrupt
the flow and mixing of the urea reductant 19 into the exhaust flow
12, thereby reducing the decomposition into NH3 and reducing NOx
reduction efficiency. The deposits may also block the outlet 66 or
disrupt the reductant spray 68. The formation of the deposits also
consumes urea reductant 19, making control of injection harder and
potentially reducing NOx reduction efficiency in the SCR 14. The
deposits may also corrode components of the aftertreatment system
10 and degrade the structural and thermal properties of the SCR
catalyst 14. The deposits may also block channels of the SCR
catalyst 14, again reducing NOx reduction efficiency.
[0059] The indentation 84 may help prevent the formation of the
deposits by directing the droplets 142 or spray 68 down the
straight part 22. The low intersection angle 138 created by the
downstream and upstream wall 86 and 88 and blocking effect of the
upstream wall 88 reduce the amount of reductant 19 impacting the
outer wall 96 and may prevent the formation of deposits. Likewise,
the mount angle 150 also reduces the amount of reductant 19
impacting the outer wall 96 and may prevent the formation of
deposits. The indentation 84 may also reduce recirculation of
reductant spray 68 around the outlet 66, preventing formation of
deposits around the outlet 66.
[0060] The indentation 84 also provides a recessed area or pocket
for the nozzle 18 to be located. This recessed area provides a
level of protection to the nozzle 18 and reduces the outer size of
the aftertreatment system 10 package. The indentation 84 may also
provide a flat surface 140 for mounting the nozzle 18.
[0061] Although the embodiments of this disclosure as described
herein may be incorporated without departing from the scope of the
following claims, it will be apparent to those skilled in the art
that various modifications and variations can be made. Other
embodiments will be apparent to those skilled in the art from
consideration of the specification and practice of the disclosure.
It is intended that the specification and examples be considered as
exemplary only, with a true scope being indicated by the following
claims and their equivalents.
* * * * *