U.S. patent application number 11/646547 was filed with the patent office on 2008-07-03 for filter regeneration using ultrasonic energy.
This patent application is currently assigned to CATERPILLAR INC.. Invention is credited to Herbert F.M. DaCosta, Mohamed Ibrahim Daoud.
Application Number | 20080155969 11/646547 |
Document ID | / |
Family ID | 39145049 |
Filed Date | 2008-07-03 |
United States Patent
Application |
20080155969 |
Kind Code |
A1 |
DaCosta; Herbert F.M. ; et
al. |
July 3, 2008 |
Filter regeneration using ultrasonic energy
Abstract
An exhaust treatment system of a power source system includes a
filter having an inlet and an outlet and a first exhaust line
located between the filter and a power source of the power source
system. The exhaust treatment system further includes an ultrasonic
energy generating device coupled to the filter. In addition, the
exhaust treatment system includes a second exhaust line coupled
downstream of the filter.
Inventors: |
DaCosta; Herbert F.M.;
(Peoria, IL) ; Daoud; Mohamed Ibrahim; (Dunlap,
IL) |
Correspondence
Address: |
CATERPILLAR/FINNEGAN, HENDERSON, L.L.P.
901 New York Avenue, NW
WASHINGTON
DC
20001-4413
US
|
Assignee: |
CATERPILLAR INC.
|
Family ID: |
39145049 |
Appl. No.: |
11/646547 |
Filed: |
December 28, 2006 |
Current U.S.
Class: |
60/295 |
Current CPC
Class: |
F01N 3/035 20130101;
B01D 46/46 20130101; F01N 9/002 20130101; F01N 2240/14 20130101;
B01D 46/0063 20130101; F01N 2240/04 20130101; F02B 37/00 20130101;
F01N 3/025 20130101; Y02T 10/40 20130101; Y02T 10/47 20130101; B01D
2279/30 20130101; F01N 13/107 20130101; F01N 3/027 20130101; B01D
46/0076 20130101; F01N 13/009 20140601 |
Class at
Publication: |
60/295 |
International
Class: |
F01N 3/00 20060101
F01N003/00 |
Claims
1. An exhaust treatment system of a power source system,
comprising: a filter having an inlet and an outlet; a first exhaust
line located between the filter and a power source of the power
source system; an ultrasonic energy generating device coupled to
the filter; and a second exhaust line coupled downstream of the
filter.
2. The system of claim 1, wherein the ultrasonic energy generating
device is coupled to the inlet of the filter.
3. The system of claim 1, wherein the ultrasonic energy generating
device includes a plurality of ultrasound transducers coupled to
the filter.
4. The system of claim 1, further including a regeneration device
disposed upstream of the filter.
5. The system of claim 4, wherein the regeneration device is a
fuel-driving burner coupled to the first exhaust line.
6. The system of claim 1, wherein the filter is a diesel
particulate filter.
7. The system of claim 6, wherein the filter includes catalyst
materials.
8. The system of claim 1, further including an exhaust
recirculation line located downstream of the filter.
9. A method of regenerating a filter of a combustion engine system,
comprising: directing a portion of engine exhaust flow through the
filter to collect particulate matter in the filter; and exposing at
least a portion of the filter to ultrasonic energy to bum
particulate matter in the filter.
10. The method of claim 9, wherein the filter is exposed to
ultrasonic energy when liquid resides in the filter.
11. The method of claim 10, wherein the ultrasonic energy burns the
particulate matter indirectly through heating of the liquid.
12. The method of claim 9, wherein the filter is exposed to the
ultrasonic energy when a temperature of the exhaust flow is
approximately 100.degree. C. or below.
13. The method of claim 9, wherein the filter is exposed to the
ultrasonic energy only when the engine is operating in an idle
condition.
14. The method of claim 9, wherein the filter is exposed to the
ultrasonic energy according to a predetermined schedule.
15. The method of claim 9, further including actively heating the
exhaust gas upstream of the filter to further regenerate the
filter.
16. The method of claim 15, wherein the actively heating of the
exhaust gas includes igniting a fuel-driven burner located between
the engine and the filter.
17. An exhaust treatment system of a diesel combustion engine
system, comprising: a diesel particulate filter having an inlet and
an outlet; a first exhaust line located between the filter and a
diesel combustion engine of the engine system; an ultrasonic energy
generating device coupled to the exhaust treatment system; a
controller coupled to the ultrasonic energy generating device and
configured to actuate the ultrasonic energy generating device when
conditions indicate that liquid is present in the filter; and a
second exhaust line located downstream of the filter.
18. The exhaust treatment system of claim 17, further including a
regeneration device disposed upstream of the filter and downstream
of the diesel combustion engine.
19. The exhaust treatment system of claim 17, wherein the
ultrasonic energy generating device is coupled to the inlet of the
filter.
20. The exhaust treatment system of claim 17, wherein the
ultrasonic energy generating device includes a plurality of
ultrasound tranduces coupled to the filter.
Description
TECHNICAL FIELD
[0001] This disclosure relates generally to a regeneration system
and, more particularly, to regeneration of particulate filters in a
low temperature environment.
BACKGROUND
[0002] Internal combustion engines, including diesel engines,
gasoline engines, natural gas engines, and other engines known in
the art, may exhaust a complex mixture of gaseous emissions. The
gaseous emissions may be composed of gaseous compounds, which may
include nitrous oxides (NOx), and solid particulate matter, which
may include unburned carbon particulates called soot.
[0003] 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 includes recirculating the exhaust gas. Such 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.
[0004] In many exhaust recirculation applications, the exhaust gas
is passed through a particulate filter and, in some cases, a
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
sufficiently loaded to 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 (SO.sub.3).
[0005] U.S. Pat. No. 6,793,716 to Rigaudeau et al. (the '716
patent") discloses cleaning a particulate filter using, inter alia,
ultrasonic agitation. In particular, the filter cleaning method of
the '716 patent requires removal of the filter from the exhaust
system and submerging the filter in a cleaning solution. Once in
the cleaning solution, the filter is cleaned by agitating the
cleaning solution with, for example, ultrasonic agitation. A major
drawback of the filter cleaning system of the '716 patent relates
to the time and expense associated with the required removal of the
filter from the exhaust system and the soaking of the filter in the
cleaning solution. The present disclosure is directed towards
overcoming one or more of these shortcomings.
SUMMARY OF THE INVENTION
[0006] In accordance with one disclosed exemplary embodiment, an
exhaust treatment system of a power source system includes a filter
having an inlet and an outlet and a first exhaust line located
between the filter and a power source of the power source system.
The exhaust treatment system further includes an ultrasonic energy
generating device coupled to the filter. In addition, the exhaust
treatment system includes a second exhaust line coupled downstream
of the filter.
[0007] In accordance with another disclosed exemplary embodiment, a
method of regenerating a filter of a combustion engine system
includes directing a portion of engine exhaust flow through the
filter to collect particulate matter in the filter and exposing at
least a portion of the filter to ultrasonic energy to burn
particulate matter in the filter.
[0008] According to another exemplary disclosed embodiment, an
exhaust treatment system of a diesel combustion engine system
includes a diesel particulate filter having an inlet and an outlet
and a first exhaust line located between the filter and a diesel
combustion engine of the engine system. The exhaust treatment
system further includes an ultrasonic energy generating device
coupled to the exhaust treatment system and a controller coupled to
the ultrasonic energy generating device and configured to actuate
the ultrasonic energy generating device when conditions indicate
that liquid is present in the filter. In addition, the exhaust
treatment system includes a second exhaust line located downstream
of the filter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a diagrammatic illustration of an engine having an
exhaust treatment system according to an exemplary disclosed
embodiment; and
[0010] FIG. 2 provides a diagrammatic view of a particulate filter
of the exhaust treatment system of FIG. 1.
DETAILED DESCRIPTION
[0011] 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
gaseous fluid driven 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.
[0012] 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 26 of the
power source 12. The exhaust treatment system 10 may include an
energy extraction assembly 16, a regeneration device 18, a filter
20, and a recirculation line 24 fluidly connected downstream of the
filter 20.
[0013] 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 14. The flow lines 14 may include
pipes, tubing, and/or other exhaust flow carrying means known in
the art. The flow lines 14 may be made of alloys of steel,
aluminum, and/or other materials known in the art. The flow lines
14 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.degree. C. (approximately 1,292.degree. F.).
[0014] The energy extraction assembly 16 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 16
may be fluidly connected to the power source 12 by one or more flow
lines 14 and may reduce the pressure of the exhaust gases to any
desired pressure. The energy extraction assembly 16 may include one
or more turbines of a turbocharger, diffusers, or other energy
extraction devices known in the art. It is also understood that in
another embodiment of the present disclosure, the energy extraction
assembly 16 may, alternately, be omitted. In such an embodiment,
the power source 12 may include, for example, a naturally aspirated
engine.
[0015] In an exemplary embodiment, the regeneration device 18 may
be fluidly connected downstream from the energy extraction assembly
16 via flow line 14, and may be configured to raise the temperature
of the exhaust flowing from the power source 12. The regeneration
device 18 may be controlled to raise the exhaust temperature to an
active regeneration temperature of the filter 20. Accordingly, the
regeneration device 18 may be configured to assist in regenerating
the filter 20. The regeneration device 18 may include, for example,
a fuel-driven burner including a fuel injector (as shown).
Alternatively, the regeneration device may include an electric
heater having heat coils (not shown), combustion chambers of the
power source 12, and/or other heat sources known in the art. Such
regeneration devices 18 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 18 includes a
fuel-driven burner, it is understood that the regeneration device
18 may receive a supply of a combustible substance and a supply of
oxygen to facilitate combustion within the regeneration device 18.
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 18 through flow line 14. In an exemplary
embodiment, the supply of oxygen may be delivered with a supply of
recirculated exhaust gas and ambient air to the regeneration device
18 separately from the flow of exhaust gas.
[0016] As shown in FIG. 1, the filter 20 may be connected
downstream of the regeneration device 18. The filter 20 may have a
housing 21 including an inlet 23 and an outlet 25. In an exemplary
embodiment, the regeneration device 18 may be disposed outside of
the housing 21 and may be fluidly connected to the inlet 23 of the
housing 21. In another exemplary embodiment, the regeneration
device 18 may be disposed within the housing 21 of the filter 20.
The filter 20 may be any type of filter known in the art capable of
extracting matter from a flow of gas. It is also understood that in
another embodiment of the present disclosure, the regeneration
device 18 may, alternatively, be omitted.
[0017] In an embodiment of the present disclosure, the filter 20
may be, for example, a diesel particulate matter filter positioned
to extract particulates from an exhaust flow of the power source
12. The filter 20 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 21 of the filter 20 to facilitate the removal of
particulates. The particulates may be, for example, soot contained
in the exhaust flow.
[0018] As illustrated in FIG.2, the filter 20 of the exhaust
treatment system 10 may include catalyst materials useful in
collecting, absorbing, adsorbing, and/or storing hydrocarbons,
oxides of sulfur, and/or oxides of nitrogen contained in the
exhaust 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 filter 20 so as to maximize the surface area available for
collection, adsorption, and or storage of, for example,
hydrocarbons. The catalyst materials may be located on a substrate
of the filter 20. The catalyst materials may be added to the filter
20 by any conventional means such as, for example, coating or
spraying, and the substrate of the filter 20 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 10.
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 20.
[0019] As illustrated in FIG. 2, an ultrasonic energy generating
device 32 may be coupled to the filter 20 in order to produce a
plurality of ultrasound waves 34 within at least a portion of the
main body 40 of the filter 20. The ultrasonic energy generating
device 32 may include any device, for example, a plurality of
ultrasound transducers, capable of producing ultrasound waves
within the filter 20. The ultrasonic energy generating device 32
may be configured to produce the ultrasound waves 34 manually or
automatically such as during a prescribed event, including, for
example, during or after an engine idling period. The ultrasonic
energy generating devices 32 may be controlled by an electronic
controller 19 or similar device based on measured conditions of the
power source or exhaust system. For example, the ultrasonic energy
generating device 32 may be triggered by the controller in response
to system conditions indicating that the power source 12 is
operating, or has operated, in an idle condition, that the exhaust
temperature is approximately 100.degree. C. or below, and/or
conditions indicating that liquid, such as water, is present in the
filter 20. Alternatively, controller 19 may trigger the ultrasonic
energy generating device 32 at predetermined and/or periodic
intervals.
[0020] Referring again to FIG. 1, the exhaust treatment system 10
may further include the recirculation line 24 fluidly connected
downstream of the filter 20 and upstream of an exhaust system
outlet 28. The recirculation line 24 may be configured to
controllably direct a portion of the exhaust flow from the filter
20 to the inlet 26 of the power source 12. The recirculation line
24 may include a recirculation control valve 27 activated by
electronic controller 19 to meter the amount of exhaust flow
directed back to the inlet 26 of the power source 12. The
recirculation line 24 may include piping, tubing, and/or other
exhaust flow carrying means known in the art and may be
structurally similar to the flow lines 14 described above.
INDUSTRIAL APPLICABILITY
[0021] The exhaust treatment systems 10 of the present disclosure
may be used with any combustion-type device such as, for example,
an engine, a furnace, or any other power source device known in the
art. The exhaust treatment systems 10 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 may also be capable of purging a portion of the captured
particulate matter of the exhaust gas through a regeneration
process.
[0022] As discussed above, the combustion process may produce a
complex mixture of gaseous emissions. These chemical species may
exist in solid, liquid, and/or gaseous form. In general, the solid
and liquid species may fall into four categories of ash, soot,
soluble organic fraction (SOF), and sulfates. The organic
particulate matter produced during combustion may include
carbonaceous materials and soluble organic fraction which 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 SO.sub.2. This
SO.sub.2 may react with oxygen molecules contained within the
exhaust flow to form SO.sub.3. The SO.sub.2 may also be converted
into SO.sub.3 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 SO.sub.3.
[0023] In a conventional exhaust treatment system, a portion of the
SO.sub.3 produced may be released to the atmosphere through an
outlet of the exhaust system. The exhaust treatment systems 10 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 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.
[0024] 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 14, from the
power source 12 through the energy extraction assembly 16. The
exhaust flow may pass through the regeneration device 18 to the
filter 20. The regeneration device 18 may be deactivated during the
normal operation of the power source 12. As the exhaust flow passes
through the filter 20, a portion of the particulate matter 30 (FIG.
2) entrained with the exhaust flow may be captured by the
substrate, mesh, and/or other structures within the filter 20. Any
catalyst materials, such as those disposed within the filter 20,
may assist in oxidizing the hydrocarbons and soluble organic
fraction carried by the exhaust flow.
[0025] A portion of the filtered exhaust flow may be controllably
extracted downstream of the filter 20. The extracted portion of the
exhaust flow may enter the recirculation line 24 and may be
recirculated back to the power source 12. After passing through the
filter 20, a portion of the exhaust flow may also exit the exhaust
treatment system 10 through an exhaust system outlet 28.
[0026] Over time, particulate matter/soot 30 produced by the
combustion process may collect in the filter 20 and may begin to
impair the exhaust treatment system. Sensors (not shown) may be
configured to sense parameters of the power source 12 and/or the
exhaust treatment system 10 to determine the loading of the filter
20. Such parameters may include, for example, engine speed, engine
temperature, exhaust flow temperature, exhaust flow pressure, and
particulate matter content. Controller 19 may use the information
sent from the sensors in conjunction with an algorithm or other
pre-set criteria to determine whether the filter 20 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 19 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.
[0027] During prolonged engine idling events, the exhaust flow and
filter 20 may obtain a reduced temperature, for example,
approximately 100.degree. C. or below. As a result, moisture, such
as condensation of liquid water, may develop within the filter 20.
Thus, as the exhaust flow travels in a first flow direction 36 into
the inlet 23 of the filter 20, an amount of soot, such as
particulate matter 30, entrained within the exhaust flow may become
saturated with moisture contained within the filter 20. When such
moisture is contained within the filter 20, the ultrasonic energy
generating device 32 may be configured to receive signals from
controller 19 to begin a regeneration process. The regeneration
process may include enabling the ultrasonic energy generating
device 32 to produce ultrasound waves 34 within at least a portion
of the filter 20. The moisture surrounding an amount of particulate
matter soot 30, may be exposed to the ultrasound waves 34 to form
microbubbles in the moisture layer. The microbubbles may begin to
oscillate as a result of exposure to the ultrasound waves 34. This
may produce hot spots as the oscillating microbubbles generate heat
and increased temperatures around the encapsulated soot particles.
Additional processes, such as cavitation, may also occur as the
microbubbles oscillate under high heat and increased temperature.
Regeneration of the soot may occur as the microbubbles combust
under cavitation and the heat generated by the hot spots is
received by the particulate matter 30. The heat generated under the
regeneration process of the disclosed embodiment may be sufficient
such that soot contained within the filter 20 may be burned away to
restore the storage some or all of the capability of the filter 20.
This indirect method of filter regeneration does not require
significant fuel consumption to provide the heat sufficient for
filter regeneration. Regeneration device 18 may be initiated
concurrently with the initiation of the ultrasonic energy
generating device 32, or under may be initiated based on different
sensed or predetermined conditions.
[0028] Other embodiments of the disclosed exhaust treatment system
10 will be apparent to those skilled in the art from consideration
of the specification. For example, the system 10 may include
additional devices including, for example, a liquid injection
device configured to supply moisture to the filter 20 in order to
facilitate saturation of the soot within the filter 20. Other
devices may include equipment to artificially cool down the filter
and/or exhaust flow received therein to change saturation of the
particulate matter in the filter. 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.
[0029] It will be apparent to those skilled in the art that various
modifications and variations can be made in the disclosed apparatus
and method without departing from the scope of the disclosure.
Additionally, other embodiments of the apparatus and method will be
apparent to those skilled in the art from consideration of the
specification. It is intended that the specification and examples
be considered as exemplary only, with a true scope of the
disclosure being indicated by the following claims and their
equivalents.
* * * * *