U.S. patent application number 14/510141 was filed with the patent office on 2015-01-22 for reductant supply system.
This patent application is currently assigned to Caterpillar Inc.. The applicant listed for this patent is Caterpillar Inc.. Invention is credited to Brian M. Cole, James J. Driscoll, Jinhui Sun.
Application Number | 20150023843 14/510141 |
Document ID | / |
Family ID | 52343716 |
Filed Date | 2015-01-22 |
United States Patent
Application |
20150023843 |
Kind Code |
A1 |
Driscoll; James J. ; et
al. |
January 22, 2015 |
REDUCTANT SUPPLY SYSTEM
Abstract
An aftertreatment system is disclosed. The aftertreatment system
includes an exhaust conduit and a selective catalytic reduction
module. The aftertreatment system also includes a reductant supply
system. The reductant supply system includes a reductant tank, a
reductant injector, and a pump assembly. The pump assembly includes
a reversing valve assembly and a pump unit. The pump assembly also
includes a plurality of check valves, a pressure sensor, and a
filter. Further, the reductant supply system includes a back flow
valve assembly. The reductant supply system also includes at least
two header units associated with the pump assembly. The at least
two header units include a reductant draw conduit and at least one
heat exchanger. The at least two header units also include a bag
filtration assembly.
Inventors: |
Driscoll; James J.; (Dunlap,
IL) ; Cole; Brian M.; (Peoria, IL) ; Sun;
Jinhui; (Dunlap, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Caterpillar Inc. |
Peoria |
IL |
US |
|
|
Assignee: |
Caterpillar Inc.
Peoria
IL
|
Family ID: |
52343716 |
Appl. No.: |
14/510141 |
Filed: |
October 9, 2014 |
Current U.S.
Class: |
422/168 |
Current CPC
Class: |
F01N 2610/02 20130101;
F01N 2610/1426 20130101; Y02T 10/24 20130101; F01N 2610/1433
20130101; F01N 2610/1473 20130101; F01N 3/208 20130101; Y02T 10/12
20130101 |
Class at
Publication: |
422/168 |
International
Class: |
F01N 3/20 20060101
F01N003/20 |
Claims
1. An aftertreatment system comprising: an exhaust conduit; a
selective catalytic reduction module configured to receive an
exhaust gas flow from the exhaust conduit; and a reductant supply
system configured to supply a reductant into the exhaust conduit
upstream of the selective catalytic reduction module, the reductant
supply system comprising: a reductant tank; a reductant injector; a
pump assembly in fluid communication with the reductant tank and
the reductant injector, the pump assembly comprising: a reversing
valve assembly; a pump unit; a plurality of check valves associated
with the pump unit; a pressure sensor; and a filter; a back flow
valve assembly in fluid communication with the pump assembly and
the reductant tank; at least two header units associated with the
pump assembly, each of the at least two header units comprising: a
reductant draw conduit configured to supply the reductant from the
reductant tank to the pump assembly; and at least one heat
exchanger; and a bag filtration assembly provided on each of the at
least two header units.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to an aftertreatment system,
and more particularly to a reductant supply system for the
aftertreatment system.
BACKGROUND
[0002] An aftertreatment system is associated with an engine
system. The aftertreatment system is configured to treat and reduce
NOx and/or other compounds of the emissions 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 Selective Catalytic Reduction (SCR) module and a
reductant delivery module.
[0003] The reductant delivery module may include a tank for storing
a reductant, a pump unit, reductant delivery lines, and a reductant
injector. The reductant from the reductant tank may be delivered to
the reductant injector via the pump unit. For large engine systems,
reductant dosing may be increased as compared to that required by
smaller engine systems. Sometimes, in the large engine systems the
load on the reductant delivery module may increase due to thawing
time required at engine startup.
[0004] U.S. Pat. No. 8,586,895 describes a plastic vehicle tank for
an aqueous urea solution used for reducing the hydrogen oxide
content in exhaust gases of an internal combustion engine. The tank
comprises a functional unit comprising at least one pump, at least
one pressure control valve, at least one internal container
provided with an internal electrical heating and at least one
suction line. The functional unit is preferably mounted in the form
of a lid on the container opening for closing it.
SUMMARY OF THE DISCLOSURE
[0005] In one aspect of the present disclosure, an aftertreatment
system is disclosed. The aftertreatment system includes an exhaust
conduit. The aftertreatment system also includes a selective
catalytic reduction module configured to receive an exhaust gas
flow from the exhaust conduit. The aftertreatment system also
includes a reductant supply system configured to supply a reductant
into the exhaust conduit upstream of the selective catalytic
reduction module. The reductant supply system includes a reductant
tank. The reductant supply system also includes a reductant
injector. The reductant supply system further includes a pump
assembly provided in fluid communication with the reductant tank
and the reductant injector. The pump assembly includes a reversing
valve assembly. The pump assembly also includes a pump unit. The
pump assembly further includes a plurality of check valves
associated with the pump unit. The pump assembly includes a
pressure sensor. The pump assembly also includes a filter. The
reductant supply system includes a back flow valve assembly
provided in fluid communication with the pump assembly and the
reductant tank. The reductant supply system also includes at least
two header units associated with the pump assembly. The at least
two header units include a reductant draw conduit configured to
supply the reductant from the reductant tank to the pump assembly.
The at least two header units also include at least one heat
exchanger. The at least two header units further include a bag
filtration assembly provided on each of the at least two header
units.
[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 block diagram of an exemplary engine system
including an aftertreatment system, according to one embodiment of
the present disclosure;
[0008] FIG. 2 is a schematic view of a reductant supply system of
the aftertreatment system, according to one embodiment of the
present disclosure;
[0009] FIG. 3 is cross-sectional view of a reductant tank including
two header units, according to one embodiment of the present
disclosure; and
[0010] FIG. 4 is a perspective view of one of the two header units,
according to one embodiment of the present disclosure.
DETAILED DESCRIPTION
[0011] 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 block 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. According to one embodiment of the
disclosure, 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.
[0012] The engine 102 may include other components, 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
any machine including, but not limited to, an on-highway truck, an
off-highway truck, an earth moving machine, an electric generator,
and so on. Further, the engine system 100 may be associated with an
industry including, but not limited to, transportation,
construction, agriculture, forestry, power generation, and material
handling.
[0013] The engine system 100 includes an exhaust aftertreatment
system 104 fluidly connected to an exhaust manifold of the engine
102. The aftertreatment system 104 is configured to treat an
exhaust gas flow exiting the exhaust manifold of the engine 102.
The exhaust gas flow contains emission compounds that may include
Nitrogen Oxides (NOx), unburned hydrocarbons, particulate matter
and/or other combustion products known in the art. The
aftertreatment system 104 may be configured to trap or convert NOx,
unburned hydrocarbons, particulate matter, combinations thereof, or
other combustion products in the exhaust gas flow before exiting
the engine system 100.
[0014] In the illustrated embodiment, the aftertreatment system 104
includes a first module 106 that is fluidly connected to an exhaust
conduit 108 of the engine 102. During engine operation, the first
module 106 is arranged to internally receive engine exhaust gas
from the exhaust conduit 108. The first module 106 may contain
various exhaust gas treatment devices, such as, a Diesel Oxidation
Catalyst (DOC) 110 and a Diesel Particulate Filter (DPF) 112, but
other devices may be used. The first module 106 and the components
found therein are optional and may be omitted for various engine
applications in which the exhaust treatment function provided by
the first module 106 is not required.
[0015] In the illustrated embodiment, the exhaust gas provided to
the first module 106 by the engine 102 may first pass through the
DOC 110 and then through the DPF 112 before entering a transfer
conduit 114. The aftertreatment system 104 includes a reductant
supply system 116. A reductant is injected into the transfer
conduit 114 by a reductant injector 118. 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] Referring to FIG. 2, the reductant is contained within a
reductant tank 120 (see FIG. 2). Parameters related to the
reductant tank 120 such as size, shape, location, and material used
may vary according to system design and requirements. Further, the
reductant injector 118 may be communicably coupled to a controller
212. Based on control signals received from the controller 212, the
reductant from the reductant tank 120 is provided to the reductant
injector 118 by a pump assembly 122. In one embodiment, the
reductant supply system 116 may include two or more reductant
injectors 118. The number of the reductant injector 118 may vary
based on the type of application. Various components of the
reductant supply system 116 will be explained in detail in
connection with FIGS. 2-4.
[0017] As the reductant is injected into the transfer conduit 114,
the reductant mixes with the exhaust gas passing therethrough, and
is carried to a second module 124. Further, the transfer conduit
114 is configured to fluidly interconnect the first module 106 with
the second module 124, such that, the exhaust gas from the engine
102 may pass through the first and second modules 106, 124 in
series before being released at a stack 126 connected downstream of
the second module 124. The second module 124 encloses a Selective
Catalytic Reduction (SCR) module 128 and an Ammonia Oxidation
Catalyst (AMOX) 130. The SCR module 128 operates to treat exhaust
gases exiting the engine 102 in the presence of ammonia, which is
provided after degradation of a urea-containing solution injected
into the exhaust gases in the transfer conduit 114. The AMOX 130 is
used to convert any ammonia slip from the downstream flow of the
SCR module 128 before exiting the exhaust gas through the stack
126.
[0018] Further, in order to promote mixing of the reductant with
the exhaust gas, a mixer 132 may be disposed along the transfer
conduit 114. The mixing of the reductant with the exhaust gas is
not limited to a separate mixer 132 but may be accomplished with
other known techniques, such as, a curved transfer conduit 114. The
amount of the reductant that may be injected into the transfer
conduit 114 may be appropriately metered based on engine operating
conditions.
[0019] 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.
[0020] FIG. 2 is a schematic view of the reductant supply system
116. According to an exemplary embodiment, the reductant tank 120
of the reductant supply system 116 includes two or more header
units. In the illustrated embodiment, the reductant tank 120
includes a first header unit 202 and a second header unit 302. In
one embodiment, the reductant tank 120 may include three or more
such header units based on the type of application. The first and
second header units 202, 302 may be threadably coupled with a top
portion of the reductant tank 120. Alternatively, the first and
second header units 202, 302 may be welded, bolted, or brazed to
the reductant tank 120.
[0021] As shown in FIGS. 2 and 3, each of the first and second
header units 202, 302 include a reductant draw conduit 206, 306.
The reductant draw conduits 206, 306 extend into the reductant tank
120. The reductant draw conduit 206, 306 is arranged and configured
to draw the reductant present within the reductant tank 120.
[0022] Further, a heat exchanger 210, 310 is provided in
association with each of the first and second header units 202,
302. The heat exchanger 210, 310 is configured to receive a coolant
flow from a coolant system. The coolant may be any engine coolant
that is configured to cool the engine 102. The coolant is generally
at a temperature which is higher than that of the reductant, due to
heat transfer between the coolant and various engine parts.
[0023] A coolant flow valve (not shown) may be associated with the
coolant system and may be communicably coupled to the controller
212. Based on an actuation signal received from the controller 212,
the coolant flow valve may be actuated and the coolant may flow
into the heat exchanger 210, 310 via a coolant inlet line 214, 314
associated with the first and second header units 202, 302. The
coolant flow through the first and second header units 202, 302 is
configured to exchange heat with the reductant present within the
reductant tank 120, thereby increasing the temperature of the
reductant in the reductant tank 120. Further, after passing through
the heat exchanger 210, 310 the coolant may flow out of the first
and second header units 202, 302 through a coolant outlet line 216,
316 respectively. A coolant pump (not shown) may be provided in
fluid communication with the coolant system. The coolant pump is
configured to pump and deliver the coolant from a source such as a
coolant tank (not shown) to various components of the
aftertreatment system 104.
[0024] Further, each of the first and second header units 202, 302
may also include a level sensor 218, 318 (see FIG. 3). As shown in
the accompanying figures, the level sensor 218, 318 is positioned
along the reductant draw conduit 206, 306 of the first and second
header units 202, 302 respectively. The level sensor 218, 318 is
configured to determine an amount or quantity of the reductant
present within the reductant tank 120. The level sensor 218, 318
may be embodied as a float operated sensor or any other sensor
known in the art to detect a level of the reductant in the
reductant tank 120.
[0025] Each of the first and second header units 202, 302 may
include a temperature sensor 219, 319. The temperature sensors 219,
319 may be configured to determine a temperature of the reductant
present within the reductant tank 120. The level sensors 218, 318
and the temperature sensors 219, 319 may be communicably coupled to
the controller 212 (see FIG. 2). The reductant draw conduits 206,
306 of the first and second header units 202, 302 respectively may
include a pick-up screen (not shown). The pick-up screen may be
configured to restrict an entry of ice into the reductant draw
conduits 206, 306. This ice may be formed due to freezing of the
reductant present in the reductant tank 120. One of ordinary skill
in the art would understand that various additional components may
be added or certain components could be removed depending on the
application of the header unit 202, 302.
[0026] Each of the first and second header units 202, 302 may
additionally include a bag filtration assembly 220, 320. FIG. 4
shows a perspective view of the bag filtration assembly 220, 320 of
the first or second header unit 202, 302 respectively. The bag
filtration assembly 220, 320 is embodied as a sock filter. The bag
filtration assembly 220, 320 is a high surface area porous filter,
and is configured to protect the pick-up screen from debris that
may be present within the reductant tank 120. The bag filtration
assembly 220, 320 is further configured to enclose and protect the
reductant draw conduit 206, 306, the heat exchanger 210, 310, and
any other allied components of the first and second header units
202, 302 from exposure to debris present within the reductant tank
120.
[0027] Referring to FIG. 3, the reductant tank 120 may also include
an opening 222 for receiving a supply of the reductant from an
external source (not shown). The opening 222 may be closed using a
cap member 224. The opening 222 may be provided with a strainer
(not shown) in order to restrict debris present in the incoming
reductant from entering into the reductant tank 120.
[0028] Referring now to FIG. 2, each of the reductant draw conduits
206, 306 may be fluidly coupled to a supply conduit 226. The supply
conduit 226 is configured to fluidly couple the reductant draw
conduit 206, 306 with the reductant injectors 118, via the pump
assembly 122. The pump assembly 122 includes a reversing valve
assembly 228. In one embodiment, the reversing valve assembly 228
may be pressure controlled.
[0029] The reversing valve assembly 228 may be communicably coupled
with the controller 212. Based on control signals received from the
controller 212, the reversing valve assembly 228 may operate in a
first position or a second position. In the accompanying figures,
the reversing valve assembly 228 is shown in the first position.
The reversing valve assembly 228 includes a first flow passage 230
and a second flow passage 232. The first flow passage 230 of the
reversing valve assembly 228 is configured to fluidly couple the
reductant draw conduit 206, 306 to a first check valve 234. The
first check valve 234 is provided downstream of the reversing valve
assembly 228. The first check valve 234 is configured to restrict a
reverse flow of the reductant flowing therethrough.
[0030] The pump assembly 122 also includes a pump unit 236 provided
downstream of the first check valve 234. The pump unit 236 is
fluidly coupled to the reversing valve assembly 228, via the first
check valve 234. The pump unit 236 is configured to pump and
pressurize the reductant from the reductant tank 120 and supply the
pressurized reductant to the reductant injector 118. A second check
valve 238 is provided downstream of the pump unit 236. The second
check valve 238 is configured to restrict a reverse flow of the
reductant towards the pump unit 236. The first and second check
valves 234, 238 may be embodied as one way or non-return valves
that allow fluid to flow in a single direction only.
[0031] The reductant exiting the pump unit 236 is configured to
flow through the second check valve 238 and the second flow passage
232 of the reversing valve assembly 228. Further, the pump unit 236
also includes an in-line filter 240. More particularly, the in-line
filter 240 is positioned between the reversing valve assembly 228
and the reductant injector 118. The in-line filter 240 disclosed
herein may be any type of known filter.
[0032] The pump assembly 122 also includes a pressure sensor 242.
The pressure sensor 242 may be communicably coupled to the
controller 212. The pressure sensor 242 may be provided downstream
of the in-line filter 240. Under certain operating conditions, the
amount of the reductant delivered by the pump unit 236 may exceed a
reductant flow demand from the reductant injectors 118. In such a
situation, the excess amount of the reductant supplied by the pump
unit 236 may be recirculated to the reductant tank 120 via a
reductant return conduit 244.
[0033] The reductant return conduit 244 fluidly connects the supply
conduit 226 with the reductant tank 120. A back flow valve assembly
246 may be provided in the reductant return conduit 244. A portion
of excess reductant not required by the reductant injector 118 may
be recirculated from the supply conduit 226 to the reductant tank
120, through the back flow valve assembly 246. The back flow valve
assembly 246 may be communicably coupled to the controller 212.
Regulation of the back flow valve assembly 246 by the controller
212 may be based on the pressure sensed by the pressure sensor
242.
[0034] The illustrated back flow valve assembly 246 is an
electrically controlled diaphragm valve; however, alternative
embodiments may include configurations wherein the back flow valve
assembly 246 may include other valve mechanisms, such as, angle
valves, piston valves, ball valves, rotary valves, sliding cylinder
valves, etc. Further, while the back flow valve assembly 246 is
electronically controlled, one of ordinary skill in the art would
appreciate that other methods of controlling valves, e.g.,
pneumatically, or hydraulically controlled valves, may
alternatively be used.
[0035] It should be noted that the reductant supply system 116
illustrated in the accompanying figures includes a single pump
assembly 122 and a single reductant injector 118. However, based on
the type of application, the reductant supply system 116 may
include multiple pump assemblies and multiple reductant injectors
without deviating from the scope of the present disclosure.
INDUSTRIAL APPLICABILITY
[0036] Reductant supply system associated with aftertreatment
systems of large diesel engines may require a comparatively greater
amount of the reductant to be injected into the exhaust gas flow,
due to high power requirements and higher NOx reduction
requirements. In these systems an increase in demand in the
reductant injection may in turn be affected by factors like
filtration capacity of the reductant tank and thaw time during
dosing, in order to meet the injection requirements.
[0037] The present disclosure relates to the reductant supply
system 116 provided with at least two header units 202, 302 per
pump assembly 122. The number of header units per pump assembly may
be varied based upon the size of the engine 102 and also the
operating environment of the engine 102. The multiple header units
may be retrofitted to an existing reductant tank 120 of the
reductant supply system 116.
[0038] The working of the system will now be described in detail.
During a dosing operation of the reductant, the controller 212 may
send control signals to the reversing valve assembly 228 in order
to actuate and operate the reversing valve assembly 228 in the
first position. The controller 212 may then send control signals to
actuate the pump unit 236. On actuation of the pump unit 236, the
reductant from the reductant tank 120 may flow towards the pump
unit 236, via the reductant draw conduits 206, 306, the supply
conduit 226, the first flow passage 230 and the first check valve
234. From the pump unit 236, the reductant may flow towards the
reductant injectors 118, via the second check valve 238, the second
flow passage 232, and the in-line filter 240. The reductant may
then be injected into the exhaust gas flow by the reductant
injectors 118.
[0039] The first and second header units 202, 302 include the bag
filtration assembly 220, 320. The bag filtration assembly 220, 320
may increase the surface area to which the reductant may be exposed
for filtration, thereby improving the filtration capabilities of
the reductant supply system 116. The bag filtration assembly 220,
320 also protects the various components of the first and second
header units 202, 302 from the debris present within the reductant
tank 120, thus improving a service life of the components. Further,
each of the first and second header units 202, 302 also include
individual heat exchangers 210, 310 associated therewith. During an
operation of the engine 102, the heat exchangers 210, 310 may help
keep the reductant within the reductant tank 120 in a thawed
condition.
[0040] Accordingly, the reductant supply system 116 disclosed
herein may meet the dosing requirements of the large engine
systems. In some embodiments, the reductant supply system 116 may
assist in improving servicing intervals, dosing duration, and
dosing requirements by almost twice to that of existent
systems.
[0041] 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
* * * * *