U.S. patent application number 11/511216 was filed with the patent office on 2007-03-29 for exhaust treatment system.
Invention is credited to Mari Lou Balmer-Millar, David J. Kapparos, Cho Y. Liang, Cornelius N. Opris, Anil Raina, John P. Timmons.
Application Number | 20070068141 11/511216 |
Document ID | / |
Family ID | 38594619 |
Filed Date | 2007-03-29 |
United States Patent
Application |
20070068141 |
Kind Code |
A1 |
Opris; Cornelius N. ; et
al. |
March 29, 2007 |
Exhaust treatment system
Abstract
A system for ventilating a crankcase of an internal combustion
engine includes an exhaust system having a treatment element, and
the treatment element includes a catalyst configured to assist in
passively regenerating a filter of the exhaust system. The system
for ventilating the crankcase also includes first flow path
configured to transmit a first flow from the crankcase to a port
upstream of the filter, and a second flow path configured to
transmit a second flow from a combustion chamber of the internal
combustion engine to the exhaust system. The catalyst is configured
to treat a combined flow comprising the first flow and the second
flow.
Inventors: |
Opris; Cornelius N.;
(Peoria, IL) ; Timmons; John P.; (Chillicothe,
IL) ; Balmer-Millar; Mari Lou; (Chillicothe, IL)
; Liang; Cho Y.; (Peoria, IL) ; Raina; Anil;
(Chillicothe, IL) ; Kapparos; David J.;
(Chillicothe, IL) |
Correspondence
Address: |
CATERPILLAR/FINNEGAN, HENDERSON, L.L.P.
901 New York Avenue, NW
WASHINGTON
DC
20001-4413
US
|
Family ID: |
38594619 |
Appl. No.: |
11/511216 |
Filed: |
August 29, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11152069 |
Jun 15, 2005 |
7107764 |
|
|
11511216 |
Aug 29, 2006 |
|
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Current U.S.
Class: |
60/283 ; 60/280;
60/286 |
Current CPC
Class: |
F01N 3/023 20130101;
F01M 2013/0483 20130101; F01M 13/04 20130101; F01N 3/021 20130101;
F01N 13/009 20140601; F01N 3/035 20130101 |
Class at
Publication: |
060/283 ;
060/280; 060/286 |
International
Class: |
F01N 5/04 20060101
F01N005/04; F01N 3/00 20060101 F01N003/00 |
Claims
1. A system for ventilating a crankcase of an internal combustion
engine, comprising: an exhaust system including a treatment
element, the treatment element comprising a catalyst configured to
assist in passively regenerating a filter of the exhaust system; a
first flow path configured to transmit a first flow from the
crankcase to a port upstream of the filter; and a second flow path
configured to transmit a second flow from a combustion chamber of
the internal combustion engine to the exhaust system, the catalyst
being configured to treat a combined flow comprising the first flow
and the second flow.
2. The system of claim 1, wherein the treatment element further
comprises a regeneration device.
3. The system of claim 1, wherein the catalyst is an oxidation
catalyst.
4. The system of claim 1, wherein the catalyst is disposed on a
substrate of the filter.
5. The system of claim 1, wherein the catalyst includes at least
one of aluminum, platinum, palladium, rhodium, barium, cerium, an
alkali metal, an alkaline-earth metal, and a rare-earth metal.
6. The system of claim 1, wherein the filter is a diesel
particulate filter.
7. The system of claim 1, wherein the catalyst is configured to
assist in passively regenerating a filter of the treatment
element.
8. The system of claim 1, wherein the catalyst is configured to
oxidize one or more components of the combined flow.
9. The system of claim 8, wherein the one or more components of the
combined flow include particulate matter, hydrocarbons, and carbon
monoxide.
10. The system of claim 1, further including an energy extraction
assembly disposed in the second flow path and configured to reduce
the pressure of the second flow.
11. The system of claim 1, further including a third flow path
configured to transmit a portion of the treated combined flow to an
intake system of the internal combustion engine.
12. A method of controlling exhaust gases of an internal combustion
engine, comprising: pressurizing a crankcase of the internal
combustion engine; releasing a pressurized flow from the crankcase;
combining the pressurized flow with a main exhaust flow from a
combustion chamber of the internal combustion engine to form a
combined flow; treating the combined flow with a filter; and
passively regenerating at least a portion of the filter.
13. The method of claim 12, wherein treating the combined flow
includes oxidizing a component of the combined flow.
14. The method of claim 12, wherein passively regenerating at least
a portion of the filter includes at least one of burning and
removing matter trapped within the filter.
15. The method of claim 12, wherein passively regenerating at least
a portion of the filter includes increasing the temperature of the
portion of the filter to a passive temperature below a regeneration
temperature of the filter.
16. The method of claim 12, wherein treating the combined flow
includes removing particulate matter from the combined flow.
17. The method of claim 12, further including directing a portion
of the treated combined flow to an intake of the internal
combustion engine.
18. The method of claim 12, further including reducing the pressure
of the main exhaust flow.
19. The method of claim 12, further including actively regenerating
at least a portion of the filter.
20. A method of controlling exhaust gases of an internal combustion
engine, comprising: releasing a pressurized flow of exhaust from a
crankcase of the internal combustion engine; directing the
pressurized flow of exhaust to a catalyst; treating at least a
portion of the pressurized flow of exhaust with a filter; and
passively regenerating at least a portion of the filter.
21. The method of claim 20, wherein the catalyst is disposed on a
substrate of the filter.
22. The method of claim 20, wherein the catalyst is an oxidation
catalyst.
23. The method of claim 20, wherein the filter is a particulate
filter.
24. The method of claim 20, further including combining the
pressurized flow of exhaust gas with a main exhaust flow of the
combustion engine, thereby forming a combined flow.
25. The method of claim 24, further including directing the
combined flow to the catalyst.
26. The method of claim 24, further including oxidizing at least a
portion of the combined flow.
27. The method of claim 24, further including directing at least a
portion of the combined flow to an intake of the internal
combustion engine.
28. The method of claim 20, further including oxidizing at least a
portion of the pressurized flow of exhaust.
29. The method of claim 20, further including directing at least a
portion of the pressurized flow of exhaust to an intake of the
internal combustion engine.
30. The method of claim 20, wherein treating at least a portion of
the pressurized flow of exhaust includes removing matter from the
portion.
31. The method of claim 20, further including increasing the
temperature of the pressurized flow of exhaust upstream of the
catalyst.
32. The method of claim 20, further including actively regenerating
at least a portion of the filter.
33. The method of claim 20, wherein passively regenerating at least
a portion of the filter includes at least one of burning and
removing matter trapped within the filter.
34. The method of claim 20, wherein passively regenerating at least
a portion of the filter includes increasing the temperature of the
portion of the filter to a passive temperature below a regeneration
temperature of the filter.
Description
PRIORITY DATA
[0001] This application is a continuation-in-part of U.S.
application Ser. No. 11/152,069, filed Jun. 15, 2005.
TECHNICAL FIELD
[0002] The present disclosure relates generally to an exhaust
treatment system and, more particularly, to an exhaust treatment
system having a regeneration device.
BACKGROUND
[0003] Internal combustion engines, including diesel engines,
gasoline engines, natural gas engines, and other engines known in
the art, may exhaust a complex mixture of air pollutants. The air
pollutants may be composed of gaseous compounds, which may include
nitrous oxides (NOx), and solid particulate matter. Particulate
matter may include soluble organic fraction, soot (unburned
carbon), and/or hydrocarbons.
[0004] Due to increased attention on the environment, exhaust
emission standards have become more stringent, and the amount of
gaseous compounds emitted to the atmosphere from an engine may be
regulated depending on the type of engine, size of engine, and/or
class of engine. One method that has been implemented by engine
manufacturers to comply with the regulation of these engine
emissions is exhaust gas recirculation (EGR). EGR systems
recirculate the exhaust gas byproducts into the intake air supply
of the internal combustion engine. The exhaust gas directed to the
engine cylinder reduces the concentration of oxygen within the
cylinder and increases the specific heat of the air/fuel mixture,
thereby lowering the maximum combustion temperature within the
cylinder. The lowered maximum combustion temperature and reduced
oxygen concentration can slow the chemical reaction of the
combustion process and decrease the formation of NOx.
[0005] In many EGR applications, the exhaust gas is passed through
a particulate filter and catalyst containing precious metals. The
particulate filter may capture a portion of the solid particulate
matter carried by the exhaust. After a period of use, the
particulate filter may become saturated and may require cleaning
through a regeneration process wherein the particulate matter is
purged from the filter. In addition, the catalyst may oxidize a
portion of the unburned carbon particulates contained within the
exhaust gas and may convert sulfur present in the exhaust to
sulfate (SO3).
[0006] As shown in U.S. Pat. No. 6,427,436 (the '436 patent), a
filter system can be used to remove particulate matter from a flow
of engine exhaust gas before a portion of the gas is fed back to an
intake air stream of the engine. Specifically, the '436 patent
discloses an engine exhaust filter containing a catalyst and a
filter element. A portion of the filtered exhaust is extracted
downstream of the filter and is directed to an intake of the engine
through a recirculation loop.
[0007] Although the filter system of the '436 patent may protect
the engine from harmful particulate matter, the system may not be
configured to direct a flow of exhaust gas from a crankcase of the
engine to the exhaust filter for treatment, and the exhaust filter
may not be configured for passive regeneration during engine
operation.
[0008] The disclosed exhaust treatment system is directed to
overcoming one or more of the problems set forth above.
SUMMARY OF THE INVENTION
[0009] In one embodiment of the present disclosure, a system for
ventilating a crankcase of an internal combustion engine includes
an exhaust system having a treatment element, and the treatment
element includes a catalyst configured to assist in passively
regenerating a filter of the exhaust system. The system for
ventilating the crankcase also includes first flow path configured
to transmit a first flow from the crankcase to a port upstream of
the filter, and a second flow path configured to transmit a second
flow from a combustion chamber of the internal combustion engine to
the exhaust system. The catalyst is configured to treat a combined
flow comprising the first flow and the second flow.
[0010] In another embodiment of the present disclosure, a method of
controlling exhaust gases of an internal combustion engine includes
pressurizing a crankcase of the internal combustion engine,
releasing a pressurized flow from the crankcase, and combining the
pressurized flow with a main exhaust flow from a combustion chamber
of the internal combustion engine to form a combined flow. The
method further includes treating the combined flow with a filter
and passively regenerating at least a portion of the filter.
[0011] In yet another embodiment of the present disclosure, a
method of controlling exhaust gases of an internal combustion
engine includes releasing a pressurized flow of exhaust from a
crankcase of the internal combustion engine, directing the
pressurized flow of exhaust to a catalyst, and treating at least a
portion of the pressurized flow of exhaust with a filter. The
method also includes passively regenerating at least a portion of
the filter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a diagrammatic illustration of an engine having an
exhaust treatment system according to an exemplary embodiment of
the present disclosure.
[0013] FIG. 2 is a diagrammatic illustration of an engine having an
exhaust treatment system according to another exemplary embodiment
of the present disclosure.
DETAILED DESCRIPTION
[0014] FIG. 1 illustrates a power source 12 having an exemplary
exhaust treatment system 10. The power source 12 may include an
engine such as, for example, a diesel engine, a gasoline engine, a
natural gas engine, or any other engine apparent to one skilled in
the art. The power source 12 may, alternately, include another
source of power such as a furnace or any other source of power
known in the art.
[0015] The exhaust treatment system 10 may be configured to direct
exhaust gases out of the power source 12, treat the gases, and
introduce a portion of the treated gases into an intake 21 of the
power source 12. The exhaust treatment system 10 may include an
energy extraction assembly 22 and a treatment element 19. The
treatment element 19 may include, for example, a regeneration
device 20, a filter 16, and/or a catalyst 18. The exhaust treatment
system 10 may further include a recirculation line 24 fluidly
connected between the filter 16 and the catalyst 18, and a flow
cooler 26. The exhaust treatment system 10 may still further
include a flow sensor 28, a mixing valve 30, a compression assembly
32, and an aftercooler 34.
[0016] A flow of exhaust produced by the power source 12 may be
directed from the power source 12 to components of the exhaust
treatment system 10 by flow lines 15. It is understood that the
power source 12 may include one or more combustion chambers (not
shown) fluidly connected to an exhaust manifold. In such an
exemplary embodiment, the flow lines 15 may be configured to
transmit a flow of exhaust from the combustion chambers to the
components of the exhaust treatment system 10 via the exhaust
manifold. The flow lines 15 may include pipes, tubing, and/or other
exhaust flow carrying means known in the art. The flow lines 15 may
be made of alloys of steel, aluminum, and/or other materials known
in the art. The flow lines 15 may be rigid or flexible, and may be
capable of safely carrying high temperature exhaust flows, such as
flows having temperatures in excess of 700 degrees Celsius
(approximately 1,292 degrees Fahrenheit).
[0017] The energy extraction assembly 22 may be configured to
extract energy from, and reduce the pressure of, the exhaust gases
produced by the power source 12. The energy extraction assembly 22
may be fluidly connected to the power source 12 by one or more flow
lines 15 and may reduce the pressure of the exhaust gases to any
desired pressure. The energy extraction assembly 22 may include one
or more turbines 14, diffusers, or other energy extraction devices
known in the art. In an exemplary embodiment wherein the energy
extraction assembly 22 includes more than one turbine 14, the
multiple turbines 14 may be disposed in parallel or in series
relationship. It is also understood that in an embodiment of the
present disclosure, the energy extraction assembly 22 may,
alternately, be omitted. In such an embodiment, the power source 12
may include, for example, a naturally aspirated engine. As will be
described in greater detail below, a component of the energy
extraction assembly 22 may be configured in certain embodiments to
drive a component of the compression assembly 32.
[0018] In an exemplary embodiment, the regeneration device 20 of
the treatment element 19 may be fluidly connected to the energy
extraction assembly 22 via flow line 15, and may be configured to
increase the temperature of an entire flow of exhaust produced by
the power source 12 to a desired temperature. The desired
temperature may be, for example, a regeneration temperature of the
filter 16. Accordingly, the regeneration device 20 may be
configured to assist in actively regenerating the filter 16.
Alternatively, in another exemplary embodiment the regeneration
device 20 may be configured to increase the temperature of only a
portion of the entire flow of exhaust produced by the power source
12. The regeneration device 20 may include, for example, a fuel
injector and an ignitor (not shown), heat coils (not shown), and/or
other heat sources known in the art. Such heat sources may be
disposed within the regeneration device 20 and may be configured to
assist in increasing the temperature of the flow of exhaust through
convection, combustion, and/or other methods. In an exemplary
embodiment in which the regeneration device 20 includes a fuel
injector and an ignitor, it is understood that the regeneration
device 20 may receive a supply of a combustible substance and a
supply of oxygen to facilitate combustion within the regeneration
device 20. The combustible substance may be, for example, gasoline,
diesel fuel, reformate, and/or any other combustible substance
known in the art. The supply of oxygen may be provided in addition
to the relatively low pressure flow of exhaust gas directed to the
regeneration device 20 through flow line 15. In an exemplary
embodiment, the supply of oxygen may be carried by a flow of gas
directed to the regeneration device 20 from downstream of the
compression assembly 32 via a supply line 40. In such an
embodiment, the flow of gas may include, for example, recirculated
exhaust gas and ambient air. It is understood that, in an exemplary
embodiment of the present disclosure, the supply line 40 may be
fluidly connected to an outlet of the compression assembly 32. In
an exemplary embodiment, the regeneration device 20 may be
dimensioned and/or otherwise configured to be housed within an
engine compartment or other compartment of a work machine (not
shown) to which the power source 12 is attached. In such an
embodiment, the regeneration device 20, may be desirably calibrated
in conjunction with, for example, the filter 16, the energy
extraction assembly 22, the catalyst 18, and/or the power source
12. Calibration of the regeneration device 20 may include, for
example, among other things, adjusting the rate, angle, and/or
atomization at which fuel is injected into the regeneration device
20, adjusting the flow rate of the oxygen supplied, adjusting the
intensity and/or firing pattern of the ignitor, and adjusting the
length, diameter, mounting angle, and/or other configurations of a
housing of the regeneration device 20. Such calibration may reduce
the time required to regenerate the filter 16 and the amount of
fuel or other combustible substances needed for regeneration.
Either of these results may improve the overall efficiency of the
exhaust treatment system 10. It is understood that the efficiency
of the exhaust treatment systems 10, 100 described herein may be
measured by a variety of factors including, among other things, the
amount of fuel used for regeneration, the length of the
regeneration period, and the amount (parts per million) of
pollutants released to the atmosphere.
[0019] As shown in FIG. 1, the filter 16 of the treatment element
19 may be connected downstream of the regeneration device 20. The
filter 16 may have a housing 25 including an inlet 23 and an outlet
31. In an exemplary embodiment, the regeneration device 20 may be
disposed outside of the housing 25 and may be fluidly connected to
the inlet 23 of the housing 25. In another exemplary embodiment,
the regeneration device 20 may be disposed within the housing 25 of
the filter 16. The filter 16 may be any type of filter known in the
art capable of extracting matter from a flow of gas. In an
embodiment of the present disclosure, the filter 16 may be, for
example, a particulate matter filter positioned to extract
particulates from an exhaust flow of the power source 12. The
filter 16 may include, for example, a ceramic substrate, a metallic
mesh, foam, or any other porous material known in the art. These
materials may form, for example, a honeycomb structure within the
housing 25 of the filter 16 to facilitate the removal of
particulates. As discussed above, the particulates may be, for
example, soluble organic fraction, hydrocarbons, and/or soot.
[0020] In an exemplary embodiment of the present disclosure, a
portion of the exhaust produced by the combustion process may leak
past piston seal rings within a crankcase (not shown) of the power
source 12. This portion of the exhaust, often called "blow-by
gases" or simply "blow-by" may contain one or more of the exhaust
gas components discussed above. In addition, because the crankcase
is partially filled with lubricating oil being agitated at high
temperatures, the blow-by gases may also contain oil droplets and
oil vapor. The blow-by gases may build up within the crankcase over
time, thereby increasing the pressure within the crankcase. In such
an embodiment, a ventilation line 42 may be fluidly connected to
the crankcase of the power source 12.
[0021] The ventilation line 42 may comprise piping, tubing, and/or
other exhaust flow carrying means known in the art and may be
structurally similar to the flow lines 15 described above. The
ventilation line 42 may include, for example, a check valve 44
and/or any other valve assembly known in the art. The check valve
44 may be configured to assist in controllably regulating a flow of
fluid through the ventilation line 42.
[0022] The contaminants contained in blow-by gases are harmful to
the environment, and emissions concerns make direct atmospheric
venting a poor option under most, if not all, operating conditions.
In addition, directing blow-by gases back to the intake side of,
for example, a compressor in a supercharger or turbocharger can
result in fouling of the compressor wheel in a relatively short
time period. Thus, the ventilation line 42 may be configured to
direct the blow-by gases from the crankcase to a location upstream
of the filter 16 such as, for example, a port 46 of the flow line
15. For example, the ventilation line 42 may assist in directing
the portion of exhaust gas from the crankcase to a port 46 disposed
upstream of the regeneration device 20. By directing the blow-by
gases upstream of the filter 16 and/or the regeneration device 20,
the harmful contaminants contained in the blow-by gases may be
substantially removed prior to contaminating the supercharger,
turbocharger, or various power source components.
[0023] In addition, in conventional exhaust treatment systems a
cleaning device, such as, for example, an oil filter or other
conventional blow-by filter may be fluidly connected to a
ventilation line and configured to remove components of the blow-by
flow. In such systems, the cleaning device may require periodic
servicing and may increase the cost of the overall exhaust
treatment system. By directing the blow-by gases upstream of the
filter 16 and/or the regeneration device 20, as shown, for example,
FIG. 1, the exhaust treatment system 10 of the present disclosure
may eliminate the need for such cleaning devices, thereby
eliminating the need to service an extra component and minimizing
the cost of the system 10.
[0024] The exhaust treatment system 10 may further include a
catalyst 18 disposed downstream of the filter 16. The catalyst 18
may contain catalyst materials useful in collecting, absorbing,
adsorbing, and/or storing hydrocarbons, oxides of sulfur, and/or
oxides of nitrogen contained in a flow. Such catalyst materials may
include, for example, aluminum, platinum, palladium, rhodium,
barium, cerium, and/or alkali metals, alkaline-earth metals,
rare-earth metals, or combinations thereof. The catalyst materials
may be situated within the catalyst 18 so as to maximize the
surface area available for the collection of, for example,
hydrocarbons. The catalyst 18 may include, for example, a ceramic
substrate, a metallic mesh, foam, or any other porous material
known in the art, and the catalyst materials may be located on, for
example, a substrate of the catalyst 18.
[0025] As illustrated in FIG. 2, in an additional exemplary
embodiment of the present disclosure, a filter 36 of the exhaust
treatment system 100 may include catalyst materials useful in
collecting, absorbing, adsorbing, and/or storing hydrocarbons,
oxides of sulfur, and/or oxides of nitrogen contained in a flow. In
such an embodiment, the catalyst 18 (FIG. 1) may be omitted. The
catalyst materials may include, for example, any of the catalyst
materials discussed above with respect to the catalyst 18 (FIG. 1).
The catalyst materials may be situated within the filter 36 so as
to maximize the surface area available for absorption, adsorption,
and or storage. The catalyst materials may be located on a
substrate of the filter 36. The catalyst materials may be added to
the filter 36 by any conventional means such as, for example,
coating or spraying, and the substrate of the filter 36 may be
partially or completely coated with the materials. It is understood
that the presence of catalyst materials, such as, for example,
platinum and/or palladium, upstream of the recirculation line 24
may result in the formation of sulfate in the exhaust treatment
system 100. Accordingly, to minimize the amount of sulfate formed
in the exemplary embodiment of FIG. 2, only minimal amounts of
catalyst materials may be incorporated into the filter 36.
[0026] It is also understood that the catalyst materials described
above with respect to FIGS. 1 and 2 may be capable of oxidizing one
or more components of an exhaust flow such as, for example,
particulate matter, hydrocarbons, and/or carbon monoxide. Thus, in
the embodiment shown in FIG. 1, a portion of the particulate
matter, hydrocarbons, and/or carbon monoxide contained within the
exhaust flow may be permitted to travel back to the power source 12
without being oxidized by the catalyst materials. Although the
catalyst materials discussed above may assist in the formation of
sulfate, the presence of these catalyst materials, either on a
substrate of the filter 36 (FIG. 2) or in the catalyst 18 (FIG. 1),
may improve the overall emissions characteristics of the exhaust
treatment system 10, 100 by, for example, removing hydrocarbons
from the treated exhaust flow.
[0027] It is further understood that in the embodiment shown in
FIG. 2, the catalyst materials disposed on the substrate of the
filter 36 may assist in passively regenerating the filter 36 during
power source operation. As the power source 12 operates,
particulates and other components of the power source exhaust may
be trapped by the filter substrate. The exhaust flow may reach
temperatures in excess of, for example, 300 degrees Celsius during
normal operation of the power source 12 (i.e., without operating
the power source 12 in a manner so as to increase the temperature
of the exhaust by, for example, wastegating or other conventional
methods), and the exhaust gas may increase the temperature of at
least a portion of the filter substrate through convective heat
transfer. At such temperatures, the components of the power source
exhaust trapped by the substrate of the filter 36 may begin to
react with the catalyst material located on the substrate. In
particular, the catalyst material may passively regenerate a
portion of the filter 36 by oxidizing particulate matter trapped by
the filter substrate as well as carbon monoxide and/or hydrocarbons
contained in the exhaust flow. Oxidation may occur at a passive
regeneration temperature of the filter 36 in which the catalyst
material is hot enough to react with the components of the exhaust
flow without additional heat being provided by, for example, the
regeneration device 20. Such passive regeneration temperatures may
be below the regeneration temperature of the filter 36.
[0028] Although at least a portion of the particulate matter
contained within the filter 36 may be oxidized and/or removed
therefrom through passive regeneration, it is understood that, as
shown in FIG. 2, an exemplary exhaust treatment system 100 of the
present disclosure may, nonetheless, include a regeneration device
20. Utilizing a catalyzed filter 36 in conjunction with a
regeneration device 20 may assist in increasing the interval
between active regenerations. Increasing this interval may reduce
the amount of, for example, fuel burned during operation of the
power source 12, and may, thus, reduce the cost of operating the
machine to which the power source 12 is connected. An exhaust
treatment system 100 including both a catalyzed filter 36 and a
regeneration device 20 may also enable filter manufacturers to
include less catalyst material (such as, for example, precious
metals) in the filter 36, thereby reducing the cost of the filter
36 and the overall cost of the system 100.
[0029] Referring again to FIG. 1, the exhaust treatment system 10
may further include a recirculation line 24 fluidly connected
downstream of the filter 16. The recirculation line 24 may be
disposed between the filter 16 and the catalyst 18 and may be
configured to assist in directing a portion of the exhaust flow
from the filter 16 to the inlet 21 of the power source 12. The
recirculation line 24 may comprise piping, tubing, and/or other
exhaust flow carrying means known in the art and may be
structurally similar to the flow lines 15 described above. In an
embodiment in which the exhaust treatment system 100 (FIG. 2)
includes a filter 36 containing catalyst materials, the
recirculation line 24 may be disposed downstream of the filter 36
and upstream of an exhaust system outlet 17.
[0030] The flow cooler 26 may be fluidly connected to the filter 16
via the recirculation line 24 and may be configured to cool the
portion of the exhaust flow passing through the recirculation line
24. The flow cooler 26 may include a liquid-to-air heat exchanger,
an air-to air heat exchanger, or any other type of heat exchanger
known in the art for cooling an exhaust flow. In an alternative
exemplary embodiment of the present disclosure, the flow cooler 26
may be omitted.
[0031] The mixing valve 30 may be fluidly connected to the flow
cooler 26 via the recirculation line 24 and may be configured to
assist in regulating the flow of exhaust through the recirculation
line 24. It is understood that in an exemplary embodiment, a check
valve (not shown) may be fluidly connected upstream of the flow
cooler 26 to further assist in regulating the flow of exhaust
through the recirculation line 24. The mixing valve 30 may be a
spool valve, a shutter valve, a butterfly valve, a check valve, a
diaphragm valve, a gate valve, a shuttle valve, a ball valve, a
globe valve, or any other valve known in the art. The mixing valve
30 may be actuated manually, electrically, hydraulically,
pneumatically, or in any other manner known in the art. The mixing
valve 30 may be in communication with a controller (not shown) and
may be selectively actuated in response to one or more
predetermined conditions.
[0032] The mixing valve 30 may also be fluidly connected to an
ambient air intake 29 of the exhaust treatment system 10. Thus, the
mixing valve 30 may be configured to control the amount of exhaust
flow entering a flow line 27 relative to the amount of ambient air
flow entering the flow line 27. For example, as the amount of
exhaust flow passing through the mixing valve 30 is desirably
increased, the amount of ambient air flow passing through the
mixing valve 30 may be proportionally decreased and vise versa.
[0033] As shown in FIG. 1, the flow sensor 28 may be fluidly
connected to the recirculation line 24 downstream of the flow
cooler 26. The flow sensor 28 may be any type of mass air flow
sensor such as, for example, a hot wire anemometer or a
venturi-type sensor. The flow sensor 28 may be configured to sense
the amount of exhaust flow passing through the recirculation line
24. It is understood that the flow cooler 26 may assist in reducing
fluctuations in the temperature of the portion of the exhaust flow
passing through the recirculation line 24. Reducing temperature
fluctuations may also assist in reducing fluctuations in the volume
occupied by a flow of exhaust gas since a high temperature mass of
gas occupies a greater volume than the same mass of gas at a low
temperature gases. Thus, sensing the amount of exhaust flow through
the recirculation line 24 at positions downstream of the flow
cooler 26 (i.e. at a relatively controlled temperature) may result
in more accurate flow measurements than measurements taken upstream
of the flow cooler 26. It is further understood that the flow
sensor 28 may also include, for example, a thermocouple (not shown)
or other device configured to sense the temperature of the exhaust
flow.
[0034] The flow line 27 downstream of the mixing valve 30 may
direct the ambient air/exhaust flow mixture to the compression
assembly 32. The compression assembly 32 may include a compressor
13 configured to increase the pressure of a flow of gas a desired
pressure. The compressor 13 may include a fixed geometry type
compressor, a variable geometry type compressor, or any other type
of compressor known in the art. In the exemplary embodiment shown
in FIG. 1, the compression assembly 32 may include more than one
compressor 13 and the multiple compressors 13 may be disposed in
parallel or in series relationship. A compressor 13 of the
compression assembly 32 may be connected to a turbine 14 of the
energy extraction assembly 22 and the turbine 14 may be configured
to drive the compressor 13. In particular, as hot exhaust gases
exit the power source 12 and expand against the blades (not shown)
of the turbine 14, components of the turbine 14 may rotate and
drive the connected compressor 13. Alternatively, in an embodiment
in which the turbine 14 is omitted, the compressor 13 may be driven
by, for example, the power source 12, or by any other drive known
in the art. It is also understood that in a non-pressurized air
induction system, the compression assembly 32 may be omitted.
[0035] The aftercooler 34 may be fluidly connected to the power
source 12 via the flow line 27 and may be configured to cool a flow
of gas passing through the flow line 27. In an exemplary
embodiment, this flow of gas may be the ambient air/exhaust flow
mixture discussed above. The aftercooler 34 may include a
liquid-to-air heat exchanger, an air-to air heat exchanger, or any
other type of flow cooler or heat exchanger known in the art. In an
exemplary embodiment of the present disclosure, the aftercooler 34
may be omitted if desired.
[0036] The exhaust treatment system 10 may further include a
condensate drain 38 fluidly connected to the aftercooler 34. The
condensate drain 38 may be configured to collect a fluid, such as,
for example, water or other condensate formed at the aftercooler
34. It is understood that such fluids may consist of, for example,
condensed water vapor contained in recycled exhaust gas and/or
ambient air. In such an exemplary embodiment, the condensate drain
38 may include a removably attachable fluid tank (not shown)
capable of safely storing the condensed fluid. The fluid tank may
be configured to be removed, safely emptied, and reconnected to the
condensate drain 38. In another exemplary embodiment, the
condensate drain 38 may be configured to direct the condensed fluid
to a fluid container (not shown) and/or other component or location
on the work machine. Alternatively, the condensate drain 38 may be
configured to direct the fluid to the atmosphere or to the surface
by which the work machine is supported.
INDUSTRIAL APPLICABILITY
[0037] The exhaust treatment systems 10, 100 of the present
disclosure may be used with any combustion-type device such as, for
example, an engine, a furnace, or any other device known in the art
where the recirculation of reduced-particulate exhaust into an
inlet of the device is desired. The exhaust treatment systems 10,
100 may be useful in reducing the amount of harmful exhaust
emissions discharged to the environment and reducing or
substantially eliminating the amount of sulfate produced during
treatment of the exhaust gas. The exhaust treatment systems 10, 100
may also be capable of purging the portions of the exhaust gas
captured by components of the system through a regeneration
process.
[0038] As discussed above, the combustion process may produce a
complex mixture of air pollutants. These pollutants may exist in
solid, liquid, and/or gaseous form. In general, the solid and
liquid pollutants may fall into the three categories of soot,
soluble organic fraction, and sulfates. The soot produced during
combustion may include carbonaceous materials, and the soluble
organic fraction may include unburned hydrocarbons that are
deposited on or otherwise chemically combined with the soot. The
sulfates produced in the combustion process may be formed from
sulfur molecules contained within the fuel and may be released in
the form of SO2. This SO2 may react with oxygen molecules contained
within the exhaust flow to form SO3. As explained above, SO2 may
also be converted into SO3 in the presence of, for example,
platinum, palladium, and/or other rare earth metals used as
catalyst materials in conventional catalysts. It is understood that
the combustion process may also produce small amounts of SO3.
[0039] In a conventional exhaust treatment system, a portion of the
SO3 produced may be released to the atmosphere through an outlet of
the exhaust system. The exhaust treatment systems 10, 100 of the
present disclosure, however, may substantially reduce the formation
of sulfates by minimizing the amount of platinum, palladium, and/or
other precious earth metals used. The operation of the exhaust
treatment systems 10, 100 will now be explained in detail. Unless
otherwise noted, the exhaust treatment system 10 of FIG. 1 will be
referred to for the duration of the disclosure.
[0040] The power source 12 may combust a mixture of fuel,
recirculated exhaust gas, and ambient air to produce mechanical
work and an exhaust flow containing the gaseous compounds discussed
above. The exhaust flow may be directed, via flow line 15, from the
power source 12 through the energy extraction assembly 22. The hot
exhaust flow may expand on the blades of the turbines 14 of the
energy extraction assembly 22, and this expansion may reduce the
pressure of the exhaust flow while assisting in rotating the
turbine blades.
[0041] The reduced pressure exhaust flow may pass through the
regeneration device 20 to the filter 16. The regeneration device 20
may be deactivated during the normal operation of the power source
12. As the exhaust flow passes through the filter 16, a portion of
the particulate matter entrained with the exhaust flow may be
captured by the substrate, mesh, and/or other structures within the
filter 16.
[0042] A portion of the filtered exhaust flow may be extracted
downstream of the filter 16 and upstream of the catalyst 18. The
extracted portion of the exhaust flow may enter the recirculation
line 24 and may be recirculated back to the power source 12. The
remainder of the filtered exhaust flow may pass through the
catalyst 18. The catalyst materials contained within the catalyst
may assist in oxidizing the hydrocarbons and soluble organic
fraction carried by the filtered flow. After passing through the
catalyst 18, the remainder of the filtered exhaust flow may exit
the exhaust treatment system 10 through an exhaust system outlet
17.
[0043] The embodiment of the exhaust treatment system 10
illustrated in FIG. 1 may be preferable to conventional systems
since, although the exhaust treatment system 10 contains a separate
catalyst 18, the catalyst 18 is downstream of the recirculation
line 24. As a result, any of the SO3 produced by the rare earth
metals contained within the catalyst 18 exits through the outlet 17
and is not recirculated through the exhaust treatment system 10. It
is understood, however, that since the catalyst 18 is downstream of
the recirculation line 24, a portion of the hydrocarbons produced
during the combustion process may be recirculated back to the power
source 12.
[0044] In the exemplary embodiment illustrated in FIG. 2, the
filter 36 may contain catalyst materials such as platinum. The
catalyst materials may be disposed on a substrate of the filter 36
and may substantially oxidize the particulate matter, hydrocarbons,
and/or carbon monoxide contained within the exhaust flow. Such a
configuration may result in the production of substantially less
sulfate in the recirculated filtered exhaust flow than conventional
exhaust treatment systems containing a separate catalyst upstream
of a filter. Such a configuration may also allow for the passive
regeneration of the filter 36 during operation of the power source
12.
[0045] Referring again to FIG. 1, the recirculated portion of the
exhaust flow may pass through the flow cooler 26. The flow cooler
26 may reduce the temperature of the portion of the exhaust flow
before the portion enters the flow line 27. The mixing valve 30 may
be configured to regulate the ratio of recirculated exhaust flow to
ambient inlet air passing through flow line 27. As described above,
the flow sensor 28 may assist in regulating this ratio.
[0046] The mixing valve 30 may permit the ambient air/exhaust flow
mixture to pass to the compression assembly 32 where the
compressors 13 may increase the pressure of the flow, thereby
increasing the temperature of the flow. The compressed flow may
pass through the flow line 27 to the aftercooler 34, which may
reduce the temperature of the flow before the flow enters the inlet
21 of the power source 12.
[0047] Over time, soot produced by the combustion process may
collect in the filter 16 and may begin to impair the ability of the
filter 16 to store particulates. The flow sensor 28 and other
sensors (not shown) sense parameters of the power source 12 and/or
the exhaust treatment system 10. Such parameters may include, for
example, engine speed, engine temperature, exhaust flow
temperature, exhaust flow pressure, and particulate matter content.
A controller (not shown) may use the information sent from the
sensors in conjunction with an algorithm or other pre-set criteria
to determine whether the filter 16 has become saturated and is in
need of regeneration. Once this saturation point has been reached,
the controller may send appropriate signals to components of the
exhaust treatment system 10 to begin the regeneration process. A
preset algorithm stored in the controller may assist in this
determination and may use the sensed parameters as inputs.
Alternatively, regeneration may commence according to a set
schedule based on fuel consumption, hours of operation, and/or
other variables.
[0048] The signals sent by the controller may alter the position of
the mixing valve 30 to desirably alter the ratio of the ambient
air/exhaust flow mixture. These signals may also activate the
regeneration device 20. Upon activation, oxygen and a combustible
substance, such as, for example, fuel may be directed to the
regeneration device 20. The regeneration device 20 may ignite the
fuel and may increase the temperature of the exhaust flow passing
to the filter 16 to a desired temperature for regeneration. This
temperature may be in excess of 700 degrees Celsius (approximately
1,292 degrees Fahrenheit) in some applications, depending on the
type and size of the filter 16. At these temperatures, soot
contained within the filter 16 may be burned away to restore the
storage capabilities of the filter 16.
[0049] Other embodiments of the disclosed exhaust treatment system
10, 100 will be apparent to those skilled in the art from
consideration of the specification. For example, the system 10, 100
may include additional filters such as, for example, a sulfur trap
disposed upstream of the filter 16. The sulfur trap may be useful
in capturing sulfur molecules carried by the exhaust flow. It is
intended that the specification and examples be considered as
exemplary only, with the true scope of the invention being
indicated by the following claims.
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