U.S. patent application number 14/702762 was filed with the patent office on 2015-08-20 for modular assembly for aftertreatment system.
This patent application is currently assigned to Caterpillar Inc.. The applicant listed for this patent is Caterpillar Inc.. Invention is credited to Thomas Ryan Cassity, Christopher A. Willey.
Application Number | 20150233276 14/702762 |
Document ID | / |
Family ID | 53797681 |
Filed Date | 2015-08-20 |
United States Patent
Application |
20150233276 |
Kind Code |
A1 |
Cassity; Thomas Ryan ; et
al. |
August 20, 2015 |
MODULAR ASSEMBLY FOR AFTERTREATMENT SYSTEM
Abstract
A modular assembly for an exhaust aftertreatment system is
provided. The modular assembly includes an inlet portion. The
modular assembly also includes a mixing element. The modular
assembly further includes a first frusto-conical region diverging
from the inlet portion. The modular assembly also includes a
selective catalytic reduction assembly provided within a central
portion of the housing. The selective catalytic reduction assembly
includes a bank of catalysts. The modular assembly further includes
a sound suppression element provided within the central portion of
the housing and positioned downstream of the selective catalytic
reduction assembly. The modular assembly includes a baffle
arrangement provided within the central portion of the housing, the
baffle arrangement includes a first baffle and a second baffle. The
modular assembly also includes a second frusto-conical region
converging from the central portion of the housing. The modular
assembly further includes an outlet portion connected to the second
frusto-conical region.
Inventors: |
Cassity; Thomas Ryan;
(Decatur, IL) ; Willey; Christopher A.; (Decatur,
IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Caterpillar Inc. |
Peoria |
IL |
US |
|
|
Assignee: |
Caterpillar Inc.
Peoria
IL
|
Family ID: |
53797681 |
Appl. No.: |
14/702762 |
Filed: |
May 4, 2015 |
Current U.S.
Class: |
422/176 |
Current CPC
Class: |
F01N 2610/02 20130101;
Y02T 10/12 20130101; F01N 3/2892 20130101; F01N 3/2885 20130101;
F01N 3/2066 20130101; Y02T 10/24 20130101; F01N 1/083 20130101;
F01N 13/017 20140601; F01N 1/10 20130101 |
International
Class: |
F01N 3/28 20060101
F01N003/28; F01N 13/02 20060101 F01N013/02; F01N 1/10 20060101
F01N001/10; F01N 3/20 20060101 F01N003/20; F01N 1/08 20060101
F01N001/08 |
Claims
1. A modular assembly for an exhaust aftertreatment system, the
modular assembly comprising: an inlet portion defined by a housing
of the modular assembly, the inlet portion configured to connect to
an exhaust conduit; a mixing element positioned within the inlet
portion and downstream of a reductant injector with respect to an
exhaust gas flow direction; a first frusto-conical region diverging
from the inlet portion; a selective catalytic reduction assembly
provided within a central portion of the housing, the selective
catalytic reduction assembly including a bank of catalysts
positioned in a vertical arrangement with respect to each other;
such that a central axis of each of the bank of catalysts is
parallel to a central axis of the exhaust conduit; a sound
suppression element provided within the central portion of the
housing and positioned downstream of the selective catalytic
reduction assembly; and a baffle arrangement provided within the
central portion of the housing, the baffle arrangement including a
first baffle provided upstream of the selective catalytic reduction
assembly and a second baffle provided downstream of the sound
suppression element, wherein the central portion of the housing
containing the baffle arrangement, the selective catalytic
reduction assembly, and the sound suppression element has an oblong
cross section; a second frusto-conical region converging from the
central portion of the housing; and an outlet portion connected to
the second frusto-conical region.
Description
Technical Field
[0001] The present disclosure relates to a modular assembly, and
more particularly to the modular assembly for an aftertreatment
system associated with an engine.
BACKGROUND
[0002] An aftertreatment system is associated with an engine
system. The aftertreatment system is configured to treat and reduce
oxides of nitrogen (NOx) present in an exhaust gas flow, prior to
the exhaust gas flow exiting into the atmosphere. In order to
reduce NOx, the aftertreatment system may include a reductant
delivery module, a reductant injector, and a Selective Catalytic
Reduction (SCR) module.
[0003] The aftertreatment system may additionally include a muffler
assembly having a sound suppression element. The sound suppression
element performs sound attenuation function and suppresses noise of
high pressure created by the exhaust gas. Generally, the muffler
assembly is provided as a separate module downstream of the SCR
module. In some examples, the SCR module and the sound suppression
element are integrated into a single muffler assembly. However, the
SCR module includes square cross-sectioned SCR units. Such shape of
the SCR units may lead to an increase in stresses caused due to
pressure pulsations. Further, stresses are also induced across weld
joints thereby affecting a mounting of the SCR units within the
muffler assembly. In some situations, such a design of the SCR
units causes increase in hoop stresses.
[0004] U.S. Pat. No. 5,578,277 hereinafter referred to as '277
patent, describes a modular catalytic converter and muffler used to
purify exhaust from a relatively large diesel engine. The modular
catalytic converter and muffler includes a plurality of catalytic
converter sub-cans mounted within a housing of the modular
catalytic converter and muffler. The modular catalytic converter
and muffler also includes a flow distributor mounted within the
housing upstream of the catalytic converter sub-cans. Further, a
muffler structure is mounted within the housing between the
catalytic converter sub-cans and an outlet in order to attenuate
noise in the exhaust. However, the modular catalytic converter and
muffler of the '277 patent has a bulky structure.
SUMMARY OF THE DISCLOSURE
[0005] In one aspect of the present disclosure, a modular assembly
for an exhaust aftertreatment system is provided. The modular
assembly includes an inlet portion defined by a housing of the
modular assembly. The inlet portion is configured to connect to an
exhaust conduit. The modular assembly also includes a mixing
element positioned within the inlet portion and downstream of a
reductant injector with respect to an exhaust gas flow direction.
The modular assembly further includes a first frusto-conical region
diverging from the inlet portion. The modular assembly also
includes a selective catalytic reduction assembly provided within a
central portion of the housing. The selective catalytic reduction
assembly includes a bank of catalysts positioned in a vertical
arrangement with respect to each other. A central axis of each of
the bank of catalysts is parallel to a central axis of the exhaust
conduit. The modular assembly further includes a sound suppression
element provided within the central portion of the housing and
positioned downstream of the selective catalytic reduction
assembly. The modular assembly includes a baffle arrangement
provided within the central portion of the housing. The baffle
arrangement includes a first baffle provided upstream of the
selective catalytic reduction assembly and a second baffle provided
downstream of the sound suppression element. Further, the central
portion of the housing containing the baffle arrangement, the
selective catalytic reduction assembly, and the sound suppression
element has an oblong cross section. The modular assembly also
includes a second frusto-conical region converging from the central
portion of the housing. The modular assembly further includes an
outlet portion connected to the second frusto-conical region.
[0006] Other features and aspects of this disclosure will be
apparent from the following description and the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a schematic view of an exemplary engine system
having an aftertreatment system associated therewith, according to
one embodiment of the present disclosure;
[0008] FIG. 2 is a partial cut-away view of an exemplary modular
assembly associated with the aftertreatment system, according to
one embodiment of the present disclosure; and
[0009] FIG. 3 is a partial perspective view shown without the top
cover of the modular assembly of FIG. 2.
DETAILED DESCRIPTION
[0010] Wherever possible, the same reference numbers will be used
throughout the drawings to refer to the same or the like parts.
Referring to FIG. 1, a schematic diagram of an exemplary engine
system 100 is illustrated, according to one embodiment of the
present disclosure. The engine system 100 includes an engine 102,
which may be an internal combustion engine, such as, a
reciprocating piston engine or a gas turbine engine. The engine 102
is a spark ignition engine or a compression ignition engine, such
as, a diesel engine, a homogeneous charge compression ignition
engine, or a reactivity controlled compression ignition engine, or
other compression ignition engines known in the art. The engine 102
may be fueled by gasoline, diesel fuel, biodiesel, dimethyl ether,
alcohol, natural gas, propane, hydrogen, combinations thereof, or
any other combustion fuel known in the art.
[0011] The engine 102 may include other components (not shown),
such as, a fuel system, an intake system, a drivetrain including a
transmission system, and so on. The engine 102 may be used to
provide power to a machine (not shown) including, but not limited
to, an on-highway truck, an off-highway truck, an earth moving
machine, an electric generator, and so on. Accordingly, the engine
system 100 may be associated with an industry including, but not
limited to, transportation, construction, agriculture, forestry,
power generation, and material handling.
[0012] The engine system 100 includes an exhaust aftertreatment
system 104, hereinafter interchangeably referred to as the
aftertreatment system 104 fluidly connected to an exhaust manifold
(not shown) of the engine 102. The aftertreatment system 104 may
treat an exhaust gas flow exiting the exhaust manifold of the
engine 102. The exhaust gas flow contains emission compounds that
may include oxides of nitrogen (NOx), unburned hydrocarbons,
particulate matter, and/or other combustion products known in the
art. The aftertreatment system 104 may trap or convert NOx,
unburned hydrocarbons, particulate matter, combinations thereof, or
other combustion products present in the exhaust gas flow, before
exiting the engine system 100.
[0013] The aftertreatment system 104 includes a modular assembly
200. The modular assembly 200 is provided in fluid communication
with an exhaust conduit 106. Referring to FIG. 2, the modular
assembly 200 includes a housing 202. The housing 202 may be made
from any metal or polymer known in the art. Further, parameters
related to the housing 202 such as size, shape, location, and
material used may vary according to system design and requirements,
without limiting the scope of the present disclosure.
[0014] The housing 202 of the modular assembly 200 defines an inlet
portion 204. The inlet portion 204 may include a circular cross
section. Alternatively, the inlet portion 204 may include an
oblong, square, or rectangular cross section. The inlet portion 204
of the housing 202 receives the exhaust gas flow from the exhaust
manifold via the exhaust conduit 106 (see FIG. 1). A first end of
the inlet portion 204 is configured to connect to the exhaust
conduit 106.
[0015] Referring now to FIG. 1, the aftertreatment system 104 may
include a reductant supply system 108 associated therewith. A
reductant is injected into the inlet portion 204 (see FIG. 2) by a
reductant injector 110 associated with the reductant supply system
108. The reductant may be a fluid, such as, Diesel Exhaust Fluid
(DEF). The reductant may include urea, ammonia, or other reducing
agent known in the art.
[0016] The reductant supply system 108 includes a reductant tank
112. The reductant is contained within the reductant tank 112.
Parameters related to the reductant tank 112 such as size, shape,
location, and material used may vary according to system design and
requirements. Further, the reductant injector 110 may be
communicably coupled to a controller (not shown). Based on control
signals received from the controller, the reductant from the
reductant tank 112 is provided to the reductant injector 110 by a
pump assembly 114. The amount of the reductant that may be injected
into the inlet portion 204 may be appropriately metered based on
engine operating conditions. In one example, a NOx sensor (not
shown) may be mounted in the inlet portion 204. The NOx sensor may
measure an amount of NOx present in the exhaust gases entering the
inlet portion 204. The NOx sensor may send a signal indicative of
the NOx in the exhaust gases to the controller or an ECM (not
shown) present on board the machine. The NOx sensor 260 may include
any known sensor capable of measuring NOx present in the exhaust
gases, without limiting the scope of the present disclosure.
[0017] Referring to FIG. 2, as the reductant is injected into the
inlet portion 204, the reductant mixes with the exhaust gas flow
passing therethrough, and is carried towards a mixing element 208
positioned within the inlet portion 204. The mixing element 208 is
positioned downstream of the reductant injector 110 with respect to
an exhaust gas flow direction "F". The mixing element 208 may
embody a swirl mixer or a flapper mixer. Alternatively, any known
mixing element 208 may be used without limiting the scope of the
present disclosure. The mixing element 208 allows uniform mixing of
the exhaust gas flow and the reductant injected into the inlet
portion 204. Further, mixing vanes or turbulators may also be
associated with the modular assembly 200 to provide turbulence in
the exhaust gas flow.
[0018] The inlet portion 204 is connected to a first frusto-conical
region 216. The first frusto-conical region 216 diverges from the
inlet portion 204. More particularly, the first frusto-conical
region 216 includes a diverging profile along the exhaust gas flow
direction "F". In some examples, a surface 218 of the first
frusto-conical region 216 may make an angle of approximately
45.degree. with an axis X-X' (see FIG. 1) of the exhaust conduit
106 of the modular assembly 200. The first frusto-conical region
216 deflects a portion of the exhaust gas flow received from the
inlet portion 204.
[0019] The housing 202 includes a central portion 220. The central
portion 220 is provided downstream of the first frusto-conical
region 216 with respect to the exhaust gas flow direction "F". The
central portion 220 has an oblong cross section, having a pair of
curved sections at a top portion and a bottom portion respectively.
The curved sections of the central portion 220 respectively define
an upper interior wall 222 and a lower interior wall 224.
[0020] Referring to FIGS. 2 and 3, a baffle arrangement 226 is
provided within the housing 202 and downstream of the first
frusto-conical region 216 with respect to the exhaust gas flow
direction "F". The baffle arrangement 226 may perform a flow
distribution function in order to evenly or uniformly distribute
the exhaust gas flow received therethrough. The baffle arrangement
226 is provided and coupled to the central portion 220 of the
housing 202. The baffle arrangement 226 includes a first baffle 228
provided upstream of a selective catalytic reduction (SCR) assembly
246 with respect to the exhaust gas flow direction "F". The baffle
arrangement 226 also includes a second baffle 230. The second
baffle 230 is provided downstream of a sound suppression element
252 with respect to the exhaust gas flow direction "F". The first
and second baffles 228, 230 are provided perpendicular to the
exhaust gas flow direction "F".
[0021] The first and second baffles 228, 230 have a similar design.
The design of the first baffle 228 will now be explained in detail.
Referring to FIG. 3, a tilted cutaway perspective view of the
modular assembly 200 is illustrated. As shown, the first baffle 228
includes an oblong shape corresponding to the shape of the central
portion 220 of the housing 202. The first baffle 228 includes a
pair of curved profiles near a top end and a bottom end.
[0022] A face 236 of the first baffle 228 is defined between the
curved profiles of the first baffle 228. The face 236 of the first
baffle 228 includes a planar profile. The face 236 of the first
baffle 228 includes a number of central bores 238. In one
embodiment, the first baffle 228 includes three central bores 238.
Further, a number of openings 240 are provided on the face 236 such
that the openings 240 surround each of the central bore 238. In one
example, six openings 240 may be provided on the face 236 of the
first baffle 228. However, the number of openings 240 may vary as
per system requirements. The central bore 238 and the openings 240
allow uniform mixing and distribution of the exhaust gas flow with
the reductant.
[0023] Referring to FIG. 2, the first and second baffles 228, 230
include leg portions 242, 244. The leg portions 242, 244 extend
along the axis X-X' from the first and second baffles 228, 230.
Each of the leg portions 242, 244 connects the first and second
baffles 228, 230 to the respective walls 222, 224 of the central
portion 220 of the housing 202. The first and second baffles 228,
230 are welded to the central portion 220. In one example, an
overlapping weld or a fillet weld is used to weld the first and
second baffle 228, 230 to the central portion 220. The welding is
done in a manner that minimizes stress induced on account of
pressure pulsations. Alternatively, any other fastening means may
also be used to connect the first and second baffles 228, 230 to
the central portion 220 of the housing 202.
[0024] As shown in FIGS. 2 and 3, the modular assembly 200 includes
the SCR assembly 246 provided within the central portion 220 of the
housing 202. The SCR assembly 246 operates to treat exhaust gases
exiting the engine 102 in the presence of ammonia, which is
provided after degradation of the reductant injected into the
exhaust gas flow in the inlet portion 204. The SCR assembly 246 is
provided downstream of the first baffle 228 along the exhaust gas
flow direction "F". The SCR assembly 246 includes an oblong shape
corresponding to the shape of the central portion 220. This shape
of the SCR assembly 246 allows for a reduction in stresses caused
due to pressure pulsations.
[0025] The SCR assembly 246 includes a bank of catalysts 248
positioned in a vertical arrangement with respect to each other,
such that a central axis Y-Y' (see FIG. 2) of each of the bank of
catalysts 248 is parallel to the axis X-X' (see FIG. 1) of the
exhaust conduit 106. In one example, three catalysts 248 may be
associated with the SCR assembly 246. Alternatively, the number of
catalysts 248 may vary based on system requirements. The catalysts
248 may include a circular, oval, elliptical, oblong, or any other
cross section, without limiting the scope of the present
disclosure. It should be noted that the SCR assembly 246 is
removably mounted within the housing 202. Further, the catalysts
248 may also be removed or replaced as per requirements. The SCR
assembly 246 may include holding plates (not shown) to removably
couple the SCR assembly 246 within the housing 202. It should be
noted that the first and second baffles 228, 230 are arranged such
that the first and second baffles 228, 230 distribute the exhaust
gases uniformly across the catalysts 248.
[0026] The modular assembly 200 includes the sound suppression
element 252 provided within the housing 202. The sound suppression
element 252 is positioned downstream of the SCR assembly 246 with
respect to the exhaust gas flow direction "F". The sound
suppression element 252 is embodied as an acoustic sound-proofing
element that performs sound attenuation or noise absorbing
function. More particularly, the sound suppression element 252
reduces the amount of noise of sound pressure created by the
exhaust gas flow exiting the engine 102.
[0027] The sound suppression element 252 includes a mesh like
structure and may be made of any known sound absorbing material
known in the art that exhibits high heat resistance and high noise
absorbing efficiency. In one example, the sound suppression element
252 may include a lattice structure, and may be made of steel wool,
mineral wool, glass wool, or any permeable membrane like structure.
The sound suppression element 252 may include an oblong cross
section corresponding to the cross section of the central portion
220. Further, the sound suppression element 252 may have variable
width. More particularly, the width of the sound suppression
element 252 may be varied as per the sound attenuation
requirements.
[0028] The modular assembly 200 also includes a second
frusto-conical region 254. The second frusto-conical region 254
converges from the central portion 220 of the housing 202. The
second frusto-conical region 254 is positioned downstream of the
sound suppression element 252 with respect to the exhaust gas flow
direction "F`. The second frusto-conical region 254 may deflect and
direct the exhaust gases towards an outlet portion 256. The outlet
portion 256 is connected to, and provided downstream of the second
frusto-conical region 254 with respect to the exhaust gas flow
direction "F". In some examples, a surface 258 of the second
frusto-conical region 254 may make an angle of approximately
45.degree. with the axis X-X'. In one example, the outlet portion
256 may be provided inline with the inlet portion 204 to reduce
back-pressure within the modular assembly 200.
[0029] A NOx sensor 260 may be mounted in the outlet portion 256.
The NOx sensor 260 may measure an amount of NOx present in the
exhaust gases flowing through the outlet portion 256. The NOx
sensor 260 may send a signal indicative of the NOx in the exhaust
gases to the controller or an ECM (not shown) present on board the
machine. The NOx sensor 260 may include any known sensor capable of
measuring NOx present in the exhaust gases, without limiting the
scope of the present disclosure.
[0030] The exhaust gas flow enters the inlet portion 204 of the
modular assembly 200 from the exhaust conduit 106. As the exhaust
gases flow through the inlet portion 204, the reductant is injected
therein. As the exhaust gas flows through the inlet portion 204,
the mixing element 208 enhances mixing of the reductant with the
exhaust gas flow entering into the first frusto-conical region 216.
The exhaust gases are then deflected by the first frusto-conical
region 216, and flow through each of the baffles 228, 230, the SCR
assembly 246, and the sound suppression element 252. The treated
exhaust gases are then deflected from their path towards the outlet
portion 256. In one embodiment, the exhaust gases are let out into
the atmosphere from the outlet portion 256.
[0031] The housing 202 of the modular assembly 200 may be cast as a
unitary component. Alternatively, the components of the housing 202
such as the inlet portion 204, the first frusto-conical region 216,
the central portion 220, the second frusto-conical region 254, and
the outlet portion 256 may be manufactured as separate units and
assembled later on to form the housing 202. The components of the
housing 202 may be connected to each other using any conventional
joining process known in the art. In some situations, welding may
be used to join the components of the housing 202. For example,
overlapped welded joints may be used to join the components
together. Further, the modular assembly 200 may be supported and
secured to the machine externally via a band type or strap type
wrap-around clamp (not shown) that allow unconstrained thermal
expansion of the modular assembly 200 during operation.
[0032] The aftertreatment system 104 disclosed herein is provided
as a non-limiting example. It will be appreciated that the
aftertreatment system 104 may be disposed in various arrangements
and/or combinations relative to the exhaust manifold. These and
other variations in aftertreatment system design are possible
without deviating from the scope of the disclosure. For example,
the aftertreatment system 104 may include components (not shown),
such as, a Diesel Oxidation Catalyst (DOC) unit, a Diesel
Particulate Filter (DPF) unit, and/or an Ammonia Oxidation Catalyst
(AMOX) without limiting the scope of the disclosure.
INDUSTRIAL APPLICABILITY
[0033] The present disclosure describes providing the sound
suppression element 252 and the SCR assembly 246 within the single
modular assembly 200. The housing 202 of the modular assembly 200
has an oblong shape with overlapped welded joints. As the housing
202 has a compact shape, the modular assembly 200 can be
accommodated and mounted in a compact mounting space. This design
of the housing 202 leads to the reduction in stresses induced due
to pressure pulsations. The design of the housing 202 further
allows for a smooth flow of the exhaust gases within the housing
202. The modular assembly 200 includes the baffle arrangement 226
provided upstream of the SCR assembly 246 with respect to the
exhaust gas flow direction "F". The baffle arrangement 226
functions to uniformly distribute the exhaust gas flow across a
face of the SCR assembly 246. The first and second baffles 228, 230
are mounted diametrically opposite to each other within the housing
202 using overlapping weld or fillet weld. Such welding joints help
in the reduction in pressure pulsations and stresses induced by the
pressure pulsations.
[0034] The SCR assembly 246 includes a curved profile, as against
conventional square profile. This leads to reduction in the
stresses caused due to pressure pulsations. Hence, hoop or
circumferential stresses induced in the SCR assemblies of earlier
designs may be avoided. The SCR assembly 246 includes the catalysts
248. The catalysts 248 are removably provided within the housing
202, such that they may be conveniently removed for servicing or
replacement as per system requirements. Further, the complete SCR
assembly 246 is removably mounted within the housing 202 by the
holding plates.
[0035] The modular assembly 200 may be supported and secured to the
machine externally via band/strap type wrap-around clamps. This
type of mounting arrangement allow unconstrained thermal expansion
of the modular assembly 200 during operation, thereby reducing
stresses in the modular assembly 200 and its mounting materials.
Also, the modular assembly 200 of the present disclosure helps in
reducing backpressure developed in the system. In some examples,
the back pressure in the system may reduce from an existing 12 kPa
to 4-6 kPa. The modular assembly 200 includes fewer components and
is less bulky.
[0036] While aspects of the present disclosure have been
particularly shown and described with reference to the embodiments
above, it will be understood by those skilled in the art that
various additional embodiments may be contemplated by the
modification of the disclosed machines, systems and methods without
departing from the spirit and scope of what is disclosed. Such
embodiments should be understood to fall within the scope of the
present disclosure as determined based upon the claims and any
equivalents thereof.
* * * * *