U.S. patent application number 11/753747 was filed with the patent office on 2008-07-24 for system for reducing emissions generated from diesel engines used in low temperature exhaust applications.
Invention is credited to Julian A. Imes.
Application Number | 20080173007 11/753747 |
Document ID | / |
Family ID | 39639920 |
Filed Date | 2008-07-24 |
United States Patent
Application |
20080173007 |
Kind Code |
A1 |
Imes; Julian A. |
July 24, 2008 |
SYSTEM FOR REDUCING EMISSIONS GENERATED FROM DIESEL ENGINES USED IN
LOW TEMPERATURE EXHAUST APPLICATIONS
Abstract
Systems and methods for using off-board regeneration technology
are disclosed herein. According to one method, off-board
regeneration technology is used to allow a diesel particulate
filter to be effectively used for an engine application having an
operating temperature less than the operating temperature at which
the diesel particulate filter would normally be capable of
passively regenerating.
Inventors: |
Imes; Julian A.;
(Bloomington, MN) |
Correspondence
Address: |
MERCHANT & GOULD PC
P.O. BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Family ID: |
39639920 |
Appl. No.: |
11/753747 |
Filed: |
May 25, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60881853 |
Jan 22, 2007 |
|
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Current U.S.
Class: |
60/274 |
Current CPC
Class: |
F01N 3/023 20130101;
F01N 3/0237 20130101 |
Class at
Publication: |
60/274 |
International
Class: |
F01N 3/023 20060101
F01N003/023; F01N 3/035 20060101 F01N003/035 |
Claims
1. A method for obtaining verification for a diesel particulate
filter for use in applications having duty cycles with average
temperature profiles greater than 240 degrees Celsius for less than
40 percent of the duty cycles, the method comprising: submitting a
verification application that includes data showing that the diesel
particulate filter satisfies predetermined emission reduction
targets when used to treat exhaust generated from diesel engines
used in applications having duty cycles with average temperature
profiles greater than 240 degrees Celsius for less than 40 percent
of the duty cycles, the diesel particulate filter being used in
combination with off-board regeneration equipment including at
least one of an off-board heating device for combusting soot on the
diesel particulate filter and an off-board air moving device
adapted for blowing soot from the diesel particulate filter.
2. The method of claim 1, wherein the verification application is
an application for CARB level 2 verification, and wherein the data
shows that the diesel particulate filter satisfies an emission
reduction target required for the diesel particulate to be verified
as a CARB level 2 device.
3. The method of claim 1, wherein the verification application is
an application for CARB level 3 verification, and wherein the data
shows that the diesel particulate filter satisfies an emission
reduction target required for the diesel particulate to be verified
as a CARB level 3 device.
4. The method of claim 1, wherein the verification application
includes data showing that the diesel particulate filter satisfies
predetermined emission reduction targets when used to treat exhaust
generated from diesel engines used in applications having duty
cycles with average temperature profiles greater than 220 degrees
Celsius for less than 40 percent of the duty cycles.
5. The method of claim 1, wherein the verification application
includes data showing that the diesel particulate filter satisfies
predetermined emission reduction targets when used to treat exhaust
generated from diesel engines used in applications having duty
cycles with average temperature profiles greater than 200 degrees
Celsius for less than 40 percent of the duty cycles.
6. The method of claim 1, wherein the diesel particulate filter is
not catalyzed with a precious metal catalyst.
7. The method of claim 1, wherein the diesel particulate filter has
a precious metal catalyst loading of less than 50 grams per cubic
foot of filter substrate.
8. The method of claim 1, wherein the diesel particulate filter is
required to be removed from an exhaust system of the diesel engine
during regeneration.
9. A method for obtaining governmental verification for a diesel
particulate filter, the method comprising: verifying the diesel
particulate filter in combination with off-board regeneration
equipment, the off-board regeneration equipment including at least
one of an off-board heating device for combusting soot on the
diesel particulate filter and an off-board air moving device
adapted for blowing soot from the diesel particulate filter.
10. The method of claim 9, wherein the diesel particulate filter is
not catalyzed with a precious metal catalyst.
11. The method of claim 9, wherein the diesel particulate filter
has a precious metal catalyst loading of less than 50 grams per
cubic foot of filter substrate.
12. The method of claim 9, wherein the diesel particulate filter is
required to be removed from an exhaust system of the diesel engine
during regeneration.
13. A method of providing technology for use in treating exhaust
gas emitted from diesel engines for low temperature applications,
the method comprising: providing a diesel particulate filter system
that does not include active, on-board regeneration, the diesel
particulate filter system being verified by a governmental agency
in combination with off-board regeneration equipment, the off-board
regeneration equipment including at least one of an off-board
heating device for combusting soot on the diesel particulate filter
and an off-board air moving device adapted for blowing soot from
the diesel particulate filter.
14. The method of claim 13, wherein the diesel particulate filter
is not catalyzed with a precious metal catalyst.
15. The method of claim 13, wherein the diesel particulate filter
has a precious metal catalyst loading of less than 50 grams per
cubic foot of filter substrate.
16. The method of claim 13, wherein the diesel particulate filter
is required to be removed from an exhaust system of the diesel
engine during regeneration.
17. A method for treating exhaust from a diesel engine used for an
application having an initially measured temperature profile, the
method comprising: treating diesel engine exhaust with a diesel
particulate filter intentionally designed to not be capable of
being regularly passively regenerated at the initially measured
temperature profile; and regenerating the diesel particulate filter
with off-board regeneration equipment, the off-board regeneration
equipment including at least one of an off-board heating device for
combusting soot on the diesel particulate filter and an off-board
air moving device adapted for blowing soot from the diesel
particulate filter.
18. The method of claim 17, wherein the diesel particulate filter
is not catalyzed with a precious metal catalyst.
19. The method of claim 17, wherein the diesel particulate filter
has a precious metal catalyst loading of less than 50 grams per
cubic foot of filter substrate.
20. The method of claim 17, wherein the diesel particulate filter
is required to be removed from an exhaust system of the diesel
engine during regeneration.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Patent Application Ser. No. 60/881,853, filed Jan. 22, 2007, which
application is hereby incorporated by reference in its
entirety.
TECHNICAL FIELD
[0002] The present invention relates generally to engine exhaust
treatment systems and methods.
BACKGROUND
[0003] Vehicles equipped with diesel engines may include exhaust
systems that have diesel particulate filters for removing
particulate matter from the exhaust stream. With use, soot or other
carbon-based particulate matter accumulates on the diesel
particulate filters. As particulate matter accumulates on the
diesel particulate filters, the restriction of the filters
increases causing the buildup of undesirable back pressure in the
exhaust systems. High back pressures decrease engine efficiency.
Therefore, to prevent diesel particulate filters from becoming
excessively loaded, diesel particulate filters should be regularly
regenerated by burning off (i.e., oxidizing) the particulates that
accumulate on the filters. Since the particulate matter captured by
diesel particulate filters is mainly carbon and hydrocarbons, its
chemical energy is high. Once ignited, the particulate matter burns
and releases a relatively large amount of heat.
[0004] Systems have been proposed for regenerating diesel
particulate filters. Some systems use a fuel fed burner positioned
upstream of a diesel particulate filter to cause regeneration (see
U.S. Pat. No. 4,167,852). Other systems use an electric heater to
regenerate a diesel particulate filter (see U.S. Pat. Nos.
4,270,936; 4,276,066; 4,319,896; 4,851,015; 4,899,540; 5,388,400
and British Published Application No. 2,134,407). Detuning
techniques are also used to regenerate diesel particulate filters
by raising the temperature of exhaust gas at selected times (see
U.S. Pat. Nos. 4,211,075 and 3,499,260). Self regeneration systems
have also been proposed. Self regeneration systems can use a
catalyst on the substrate of the diesel particulate filter to lower
the ignition temperature of the particulate matter captured on the
filter. An example of a self regeneration system is disclosed in
U.S. Pat. No. 4,902,487.
[0005] Air quality/emissions regulations at the state and federal
level have driven manufacturers to develop improved diesel engine
emission control technologies that are effective over a wide range
of operating conditions and engine types. The state of California
is a leader in the implementation of diesel engine emission
regulations. The California Air Resources Board (CARB) has set
forth a verification procedure for exhaust treatment strategies
used in the treatment of diesel engine emissions. For the removal
of particulate material from diesel engine exhaust, the CARB
verification procedure defines three levels of classification which
include level 1, level 2 and level 3. An emissions control device
can be verified as a level 1 device for a specified application of
a specified category of diesel engine if it is shown to reduce
particulate material emissions by at least 25 percent. An emissions
control device can be verified as a level 2 device for a specified
application of a specified category of diesel engine if it is shown
to reduce particulate material emissions by at least 50 percent. An
emissions control device can be verified as a level 3 device for a
specified application of a specified category of diesel engine if
it is shown to reduce particulate material emissions by at least 85
percent or provides total particulate material emissions that are
less than 0.01 grams per brake horsepower-hour (g/bhp-hr).
[0006] Best Available Control Technology (BACT) regulations have
been implemented to complement emissions regulations. BACT
regulations generally require diesel engine emissions to be treated
with the best available technology that reasonably can be used for
the particular category of diesel engine. Thus, if a first
technology is verified as a level 2 device for treating a first
category of diesel engine, and a second technology is verified as a
level 3 device of treating the first category of diesel engine,
BACT dictates that the level 3 device be used.
[0007] Best Available Control Technology (BACT) regulations have
encouraged manufacturers to develop DPF's for the full operating
temperature range, making them the only alternative for 1994 and
newer engines. Passively regenerated DPF's are effective for diesel
engines that operate at relatively high temperatures. For diesel
engines that operate at relatively low temperatures, actively
regenerated DPF's using on-board electric heaters have been
developed. The difference between passively regenerated DPF's and
actively regenerated DPF's having on-board regeneration equipment
is significant. In contrast to passively regenerated DPF's,
electrically regenerated DPF's with on-board heaters require a
costly infrastructure. The market is much more interested to apply
passive DPF's due to the lower maintenance and infrastructure
costs.
SUMMARY
[0008] One aspect of the present disclosure relates to systems and
methods for using off-board regeneration technology to allow a
diesel particulate filter to be effectively used for an engine
application having an operating temperature less than the operating
temperature at which the diesel particulate filter would normally
be capable of passively regenerating.
[0009] Examples representative of a variety of inventive aspects
are set forth in the description that follows. The inventive
aspects relate to individual features as well as combinations of
features. It is to be understood that both the forgoing general
description and the following detailed description merely provide
examples of how the inventive aspects may be put into practice, and
are not intended to limit the broad spirit and scope of the
inventive aspects.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 shows an example method in accordance with the
principles of the present disclosure;
[0011] FIG. 2 shows another example method in accordance with the
principles of the present disclosure;
[0012] FIG. 3 shows an example diesel particulate filter that can
be used in accordance with aspects of the present disclosure;
[0013] FIG. 4 is a perspective view of an aftertreatment device
pulse regenerator that can be used in practicing methods in
accordance with the principles of the present disclosure;
[0014] FIG. 5 is a perspective view of the pulse regenerator of
FIG. 4 with the walls of the cabinet removed to show the interior
components;
[0015] FIG. 6 is a front view of the pulse regenerator of FIG. 4
with the two front doors removed;
[0016] FIG. 7 is a right side view of the pulse regenerator of FIG.
4 with the side wall removed;
[0017] FIG. 8 is a rear view of the pulse regenerator of FIG.
4;
[0018] FIG. 9 is a top view of the pulse regenerator of FIG. 4 with
the top wall removed;
[0019] FIG. 10 is a front view of an aftertreatment device thermal
regenerator that can be used in practicing methods in accordance
with the principles of the present disclosure;
[0020] FIG. 11 is a side view of the thermal regenerator of FIG.
10;
[0021] FIG. 12 is a perspective view of a vent and hood assembly of
the thermal regenerator of FIG. 10;
[0022] FIG. 13 is a perspective view of a heating element and
collection container of the thermal regenerator of FIG. 10;
[0023] FIG. 14 is a cross-sectional view taken along section line
14-14 of FIG. 13;
[0024] FIG. 15 is a perspective view of a base assembly of the
thermal regenerator of FIG. 10;
[0025] FIG. 16 is an end view of the base assembly of FIG. 15;
[0026] FIG. 17 shows an insulation layer for insulating an
aftertreatment device during the thermal regeneration process;
[0027] FIG. 18 is a flow chart explaining a further method in
accordance with the principles of the present disclosure;
[0028] FIG. 19 is an end view an exhaust treatment system having
active on-board regeneration;
[0029] FIG. 20 is a cross-sectional view taken along section line
20-20 of FIG. 19;
[0030] FIG. 21 is an end view of an on-board heating element used
in the exhaust treatment system of FIGS. 19 and 20;
[0031] FIG. 22 is a perspective view of a shore station used to
control regeneration of exhaust treatment devices such as the
exhaust treatment device shown in FIGS. 19 and 20; and
[0032] FIG. 23 is a schematic diagram of the shore station of FIG.
22.
[0033] While the invention is amenable to various modifications and
alternative forms, specifics thereof have been shown by way of
example in the drawings and will be described in detail below. It
is to be understood, however, that the intention is not to limit
the invention to the particular embodiments described. On the
contrary, the invention is intended to cover all modifications,
equivalents, and alternatives falling within the scope of the
disclosure.
DETAILED DESCRIPTION
[0034] For 1994 and later diesel engines, standard passively
regenerated DPF systems have been verified as level 3 devices for
applications having duty cycles with average temperature profiles
greater than 240 degrees Celsius for at least 40 percent of the
operating cycles. Specialized DPF systems capable of regenerating
at lower operating temperatures have been developed for lower
temperature applications. Such systems have been verified as level
3 devices for diesel engines used in applications having duty
cycles with average temperature profiles greater than 200 degrees
Celsius for at least 40 percent of the operating cycles. An example
of this type of specialized system is disclosed at U.S. Patent
Application Ser. No. 60/784,621, entitled Low Temperature Diesel
Particulate Matter Reduction System, and filed on Mar. 21, 2006,
that is hereby incorporated by reference in its entirety.
[0035] Passively regenerated DPF systems typically have DPF's with
relatively high catalyst loadings that assist in causing
particulate material on the DPF's to be combusted using heat
generated from the engine. However, lower temperature applications
do not provide sufficient engine heat to reliably passively
regenerate a DPF. Therefore, at present, standard DPF's are level 3
verified only for applications having high exhaust temperatures
(e.g., duty cycles with average temperature profiles greater than
240 degrees Celsius for at least 40 percent of the operating
cycles). Specialized low-temperature DPF systems of the type
identified in the previous paragraph have a wider range of use and
are level 3 verified for applications having duty cycles with
average temperature profiles greater than 200 degrees Celsius for
at least 40 percent of the operating cycles. To date, the only
verified level 3 technology that does not have operating
temperature use limitations includes active regeneration DPF
systems with on-board heating technology (e.g., electric heaters,
fuel burners, etc.) for generating the higher temperatures needed
to regenerate the DPF's.
[0036] The present disclosure relates to a strategy for using
off-board regeneration technology to economically extend the use of
a DPF system to an application having a duty cycle with an average
temperature profile lower than the average temperature profile for
which the DPF system would normally be able to passively self
regenerate in use. The average exhaust temperature profile can be
established or defined by measuring and recording engine exhaust
temperatures over repeated operating cycles (e.g., in the field or
in a test lab) using a data-logging process. The strategy proposes
allowing the application of DPF's below their normal temperature
cut-off to allow a customer to avoid using costly on-board heating
technology. There are significant capital cost and maintenance
advantages with this approach.
[0037] As shown at FIG. 1, the exhaust treatment strategy involves
the intentional application of a DPF system that does not include
active, on-board regeneration technology for applications having
normal engine operating temperatures (as determined by initial
measurement and data-logging) below the temperature cut-off for in
situ passive regeneration the DPF system (see block 2 of FIG. 1),
and then using off-board regeneration technology to regenerate the
DPF system when necessary (see block 4 of FIG. 1). To implement the
exhaust treatment strategy, the DPF system would preferably be
verified (e.g., verified under CARB, verified under the United
States Environmental Protection Agency or verified under any other
governmental exhaust emissions regulatory body) for use in treating
exhaust gas emitted from a diesel engine applications having an
average temperature profile below the temperature cut-off for
passive in situ regeneration of the DPF system being verified. In
one embodiment, the DPF system can be verified as a CARB level 3
device for applications having duty cycles with average temperature
profiles greater than 240 degrees Celsius for less than 40 percent
of the operating cycle. In another embodiment, the DPF system can
be verified as a CARB level 3 device for applications having duty
cycles with average temperature profiles greater than 220 degrees
Celsius for less than 40 percent of the operating cycle. In still
another embodiment, the DPF system can be verified as a CARB level
3 device for applications having duty cycles with average
temperature profiles greater than 200 degrees Celsius for less than
40 percent of the operating cycle.
[0038] As shown at FIG. 2, the verification process can include
submitting an application for verification of the diesel emission
control strategy to a regulating agency such as CARB, EPA, or other
regulatory body (see block 5 of FIG. 2). The verification
application can include data showing that the diesel emission
control strategy satisfies predetermined emission reduction targets
(e.g., 85 percent reduction as defined by level 3 CARB
verification) (see block 6 of FIG. 2) when used to treat exhaust
generated from diesel engines used in applications having duty
cycles with average temperature profiles greater than a
predetermined temperature (e.g., 240, 220 or 200 degrees Celsius)
for less than a certain percentage (e.g., 40 percent) of the
operating cycle. The diesel emission control strategy provided in
the application can specify a particular DPF system in combination
with an off-board DPF regeneration technology. The DPF system can
have a passive regeneration temperature requirement that will not
be met by the average exhaust temperature profile for which
verification is being sought (see block 7 of FIG. 2). Data-logging
of measured exhaust temperature values can be used to show or
verify that the engine operating temperature profile of the exhaust
generated by the engine during the given application is
insufficient to cause passive regeneration of the DPF. Data showing
compliance with a certain level of emissions reduction (e.g., CARB
level 2 or level 3 emissions reduction) can be generated using the
specified DPF system in combination with the specified off-board
DPF regeneration technology (see block 8 of FIG. 2). Regeneration
frequencies or criteria for determining when regeneration is
necessary can also be specified in the application.
[0039] After verification, the DPF system can be sold as a verified
system (e.g., a CARB level 2 or 3 verified system) for use in
treating exhaust gas emitted from diesel engines used in
applications that exceed a predetermined temperature (e.g., 240,
220 or 200 degrees Celsius) for less than a certain percentage of
their normal operating cycles (e.g., 40 percent). Literature (e.g.,
advertising, brochures, instructions, etc.) can be provided to
customers explaining that when the DPF system is used for diesel
engine applications that exceed the predetermined temperature for
less than the predetermined percentage of their normal operating
cycles, the DPF system should be periodically regenerated using
off-board DPF regeneration technology. The customer can then use
the DPF system to treat exhaust generated from diesel engine
applications that exceed the predetermined temperature for less
than the predetermined percentage of their normal operating cycles,
and can periodically have the DPF system regenerated using
off-board DPF regeneration technology. To reduce the customer's
upfront capital expenditure, the off-board regeneration services
can be provided by a party other than the customer (e.g., a service
dealer that owns and operates off-board regeneration equipment).
Thus, the customer need not purchase the off-board regeneration
technology.
[0040] A. Low Temperature Exhaust Applications
[0041] The most likely customers for this type of application
(e.g., diesel engine applications having duty cycles with average
temperature profiles greater than 240 degrees Celsius for less than
40 percent of the operating cycles) at present include refuse and
municipal fleet operators whose vehicles do not generate enough
heat for consistent or reliable filter regeneration. These fleets
are both currently regulated in California and other places, and
they need a way to retrofit their fleet with DPF's. For example,
municipal fleets generally put on only 5,000 to 10,000 miles per
year, and even when operating, they do a lot of idling and do not
generate a lot of heat. Due to cost issues, it is difficult to
justify an on-board active regeneration DPF system for this type of
vehicles with such limited operation.
[0042] B. DPF System
[0043] Diesel particulate filter substrates can have a variety of
known configurations. An exemplary configuration includes a
monolith ceramic substrate having a "honey-comb" configuration of
plugged passages as described in U.S. Pat. No. 4,851,015 that is
hereby incorporated by reference in its entirety. This type of
filter can be referred to as a wall-flow trap or filter. Common
materials used for wall-flow filters include cordierite, mullite,
alumina, SiC, refractory metal oxides or other materials. Wire
mesh, corrugated metal foil and other flow-through type filter
configurations can also be used. In certain embodiments, the filter
substrate can include a catalyst. Exemplary catalysts include
precious metals such as platinum, palladium and rhodium, and other
types of components such as base metals or zeolites.
[0044] As shown at FIG. 3, an example DPF 10 suitable for use in
treating exhaust generated from diesel engines for applications
that exceed a predetermined temperature (e.g., 240, 220 or 200
degrees Celsius) for less than 40 percent of their normal operating
cycles is depicted. The DPF 10 is a wall-flow filter having a
substrate 11 housed within an outer casing 12. In certain
embodiments, the substrate 11 can have a silicon carbide (SiC)
construction. A mat layer 13 can be mounted between the substrate
11 and the casing 12. Ends 14 of the casing can be bent radially
inwardly to assist in retaining the substrate 11 within the casing
12. End gaskets 15 can be used to seal the ends of the DPF 10 to
prevent flow from passing through the mat layer 13 to bypass the
substrate 11.
[0045] Still referring to FIG. 3, the substrate includes walls 16
defining a honeycomb arrangement of longitudinal passages 17 (i.e.,
channels) that extend from a downstream end 18 to an upstream end
19 of the substrate 11. The passages 17 are selectively plugged
adjacent the upstream and downstream ends 18, 19 such that exhaust
flow is forced to flow radially through the walls 16 between the
passages 17 in order to pass through the DPF 10. As shown at FIG.
3, this radial wall flow is represented by arrows A.
[0046] In one embodiment, the DPF can be lightly catalyzed or not
be catalyzed at all. For example, the DPF embodiment can have a
precious metal loading that is less than 50 grams per cubic foot of
substrate, or less than 30 grams per cubic foot of substrate or
less than 10 grams per cubic foot of substrate or less than 5 grams
per cubic foot of substrate. By minimizing the precious metal
loading on the DPF, the production of NO.sub.2 during treatment of
exhaust is minimized, and cost is reduced as well. In other
embodiments, the DPF can be more heavily catalyzed to reduce the
frequency at which the DPF will need to be regenerated by the
off-board regeneration equipment.
[0047] The DPF 10 preferably has a particulate mass reduction
efficiency greater than 85% so as to comply with CARB level 3
verification. Most preferably, the DPF 10 has a particulate mass
reduction efficiency equal to or greater than 90%. For the purposes
of this specification, particulate mass reduction efficiency is
determined by subtracting the particulate mass that enters the DPF
from the particulate mass that exits the DPF, and by dividing the
difference by the particulate mass that enters the DPF. The test
duration and engine cycling during testing are preferably
determined by the federal test procedure (FTP) heavy-duty transient
cycle that is currently used for emission testing of heavy-duty
on-road engines in the United States (see C.F.R. Tile 40, Part
86.1333).
[0048] Another DPF system suitable for use in treating exhaust
generated from diesel engines that exceed a predetermined
temperature (e.g., 240, 220 or 200 degrees Celsius) for less than
40 percent of their normal operating cycles is disclosed at U.S.
Patent Application Ser. No. 60/784,621, entitled Low Temperature
Diesel Particulate Matter Reduction System, and filed on Mar. 21,
2006, that is hereby incorporated by reference in its entirety. For
systems having multiple filters, selected filters of the system may
be regenerated more often than other filters of the system. Also,
in a multi-filter system, some filters may be designed to require
regular off-board regeneration while other filters may regenerate
passively on-board the vehicle.
[0049] C. Off-Board Regeneration Technology
[0050] For the purpose of this disclosure, off-board DPF
regeneration systems are DPF regeneration systems that include
off-board DPF regeneration equipment such as an off-board heating
device (e.g., a resistive heating element, a burner or other
heating devices) and/or an off-board air movement device (e.g., a
fan, a blower, a pulse generator, etc.). Off-board equipment is
defined as equipment that is not carried by the vehicle or vehicle
exhaust system during normal operation of the vehicle. In certain
embodiments, the off-board DPF regeneration equipment can be used
to regenerate a DPF of a vehicle by temporarily connecting the
off-board DPF regeneration equipment to the vehicle exhaust system
while the vehicle is stationary/parked. In such embodiments, the
DPF can be regenerated without removing the DPF from the vehicle
exhaust system. In other embodiments, the DPF is removed from the
vehicle exhaust system and regenerated by the off-board DPF
regeneration equipment at a location off-board from the vehicle. In
such embodiments, a replacement DPF can optionally be used in the
vehicle exhaust system while the removed DPF is being
regenerated.
[0051] A passive regeneration DPF system traditionally is used for
engine applications having temperatures high enough to cause self
regeneration of the DPF at fairly regular intervals without the aid
of supplemental regeneration equipment. Over an extended period of
time and many passive regeneration events, the DPF can become
plugged with ash. In the prior art, off-board cleaning technology
has been used to removed such ash. In contrast to the prior art,
one aspect of the present invention involves intentionally using a
DPF system for engine applications having temperatures too low for
the DPF system to regularly/reliably passively regenerate itself in
situ. Rather than rely on passive regeneration, off-board
regeneration equipment is used periodically to regenerate the DPF
system. The off-board regeneration equipment is not merely being
used to remove ash. Instead, a majority of the material being
removed from the DPF by the off-board regeneration equipment is
typically soot rather than ash. The off-board regeneration
equipment is used more regularly than would be necessary for mere
ash removal with respect to a passive regeneration system because
self/passive regeneration of the DPF does not regularly occur
between uses of the off-board regeneration equipment.
[0052] FIGS. 4-9 illustrate an off-board regeneration device 20
that can be used in accordance with the principles of the present
disclosure to regenerate DPF's used to treat exhaust gas emitted
from diesel engines having duty cycles with average temperature
profiles greater than 200 degrees Celsius for less than 40 percent
of the operating cycle. The regeneration device 20 includes a
cabinet 21 having a top side 22, a bottom side 24, a left side 26,
a right side 28, a front side 30 and a back side 32. The cabinet 21
includes an upper region 34, an intermediate region 36 and a lower
region 38. The front side 30 of the cabinet 21 includes a front
wall 40 positioned at the upper region 34. A pressure gage 42 and a
control panel 44 are mounted to the front wall 40. The front side
of the cabinet 21 also includes a first door 46 for providing
access to the interior of the intermediate region 36 of the cabinet
21, and a second door 48 for providing access to the interior of
the lower region 38 of the cabinet 21. An electrical connection
opening 45 and an air inlet opening 47 are provided at the top side
22 of the cabinet 21. Adjustable feet 50 are provided at the bottom
side 24 of the cabinet 21 for leveling the cabinet 21. A crank
handle 52 is provided at the side 28 of the cabinet 21. An air
outlet 54 (see FIGS. 5 and 8) is provided at the back side 32 of
the cabinet 21.
[0053] Referring to FIGS. 5-9, an air pressure tank 60 is provided
at the upper region 34 of the cabinet 21, a DPF mount 62 is
provided at the intermediate region 36 of the cabinet 21 and a
primary filter mount 64 is located at the lower region 38 of the
cabinet 21. The air pressure tank 60 and its corresponding flow
control arrangement function as a pulse generator that generates
pulses of air for regenerating a DPF 70 positioned at the DPF mount
62. A primary filter 72 positioned at the primary filter mount 64
functions to capture material flushed from the DPF 70. A safety
filter 66 is provided for re-filtering the air that passes through
the primary filter 72 before the air exits the cabinet 21 through
the air outlet 54. Further details regarding the regeneration
device 20 are provided in U.S. application Ser. No. 11/335,163,
filed Jan. 18, 2006 and entitled Apparatus for Cleaning Exhaust
Aftertreatment Devices and Methods, which is hereby incorporated
herein by reference in its entirety.
[0054] In use of the system, the DPF 10 is removed from a vehicle
having a diesel engine having exhaust that exceeds 200 degrees
Celsius for less than 40 percent of the normal operating cycle of
the vehicle. The DPF 10 is loaded at the DPF mount 62 and the
primary filter 72 is positioned at the primary filter mount 64.
With the filters 70, 72 mounted within the cabinet 21, the cabinet
doors 46, 48 are closed and the air pressure tank 60 is pressurized
with air. When the air pressure tank 60 is filled to a
predetermined air pressure, the air pressure tank 60 is opened
causing a pulse of air to flush or dump downwardly from the
pressure tank 60 through the DPF 10. As the pulse of air moves
downwardly through the DPF 10, material (e.g., soot, ash, oil,
soluble organic fraction or other material) accumulated on the DPF
10 during use is dislodged/flushed from the DPF 10 and re-captured
at the primary filter 72. After passing through the primary filter
72, the air can exit the cabinet 21 through the air outlet 54 and
its corresponding safety filter 66. A blower 74 is provided within
the cabinet 21 for providing continuous positive pressure to the
top side of the DPF 10 between air pulses. The movement of air from
the blower 74 assists in causing material loosened by the air
pulses to migrate downwardly to the primary filter 72. In other
embodiments, a vacuum may be placed downstream of the DPF and the
primary filter 72 for continuously drawing air through the DPF 10
and the primary filter 72.
[0055] It is typically preferred to mount the DPF 10 in the DPF
mount 62 with the outlet side of the filter facing upwardly toward
the pressure tank 60. In this configuration, the pulses of
compressed air back-flush collected material from the DPF. However,
in other embodiments, a filter may be regenerated by alternating
between a first orientation where the outlet side faces upwardly
toward the pressure tank 60 and a second orientation where the
outlet side faces downwardly away from the pressure tank 60. By
selectively reversing the orientation of a given filter during
regeneration, material accumulated on the filter will alternately
be exposed to pulses from opposite directions thereby assisting in
dislodging accumulated material from the filter.
[0056] Typical DPF's are 10.5 or 11.25 inches in diameter and 14
inches in length. Another common DPF size is 12 inches in diameter
and 15 inches in length. To accommodate these sizes of filter, in
one non-limiting embodiment, the air pressure tank can have a
volume of about 22 gallons, and the air pressure tank is
pressurized to about 8-10 pounds per square inch (psi) before
dumping its volume of air to generate an air pulse. In other
embodiments, the air pressure tank can have a volume in the range
5-50 gallons, or a volume of at least 5 gallons. In one
non-limiting embodiment, the air tank is pressurized to a pressure
less than 15 psi in the range of 3-15 psi. In certain embodiments,
it is desirable for the air flow through the DPF during an air
pulse to have an approach velocity of in the range of 20-100 feet
per second, or in the range of 50-70 feet per second. Approach
velocity is defined as the average speed of the air during a pulse
measured at a position immediately upstream of the DPF being
regenerated. Example pulse durations are in the range of 1/50 of a
second to 1 second or in the range of 1/30 of a second to 0.5
second. A preferred pulse duration is about 1/20 of a second. It
will be appreciated that the above numerical information is
provided for illustration purposes only, and is not intended to
limit the broad inventive aspects of the present disclosure.
[0057] In one embodiment, the entire pulse regeneration process can
be completed in 15 minutes or less. However, certain filters may
take longer than 15 minutes to regenerate. Therefore, the broad
aspects of the invention need not be limited to a particular time
frame.
[0058] It has been determined that the initial pulse is the most
effective at flushing material from an aftertreatment device.
Thereafter, the pulses progressively flush less and less material
from the device being regenerated as the device becomes
regenerated. In view of the particular effectiveness of the initial
pulses, certain aftertreatment devices may be regenerated by using
only a few pulses or even a single pulse. In practicing one method,
1-100 pulses may be used. In practicing another method, 20-70
pulses may be used. In practicing a further method, 40-60 pulses
may be used. Other numbers of pulses than those specified can also
be used without departing from the broad concept of the present
disclosure.
[0059] At times, merely pulsing air through a given filter or other
aftertreatment device may not provide adequate regeneration. For
these types of circumstances, the pulse regeneration process can be
used in combination with a heating process. For example, a DPF or
other aftertreatment device can be initially pulse regenerated as
described above. If the pulse regeneration does not result in the
adequate removal of material from the aftertreatment device, the
aftertreatment can be heated to combust soot or other combustible
materials from the filter. After combusting the combustible
material from the aftertreatment device, the aftertreatment device
can again be air pulsed to flush other remaining material from the
device.
[0060] An example off-board regeneration device 120 for combusting
soot or other materials from an aftertreatment device such as DPF
10 is disclosed at FIGS. 10-17. The device 120 includes a cabinet
121 having a rectangular housing 122 supported on legs 133 that
elevate the housing 122 above the ground. The legs 133 and a bottom
wall 124 of the housing 122 cooperate to form a base assembly 125
(see FIGS. 13 and 14) of the cabinet 121. The front of the cabinet
121 includes a door 140 that can be opened to provide access to the
interior of the housing 122. A collection container 142 is mounted
under the housing 122 for collecting material that drops from the
DPF's as the DPF's are regenerated. A vent stack 144 is mounted at
the top of the housing 122 for venting the products of combustion
from the housing 122.
[0061] Referring to FIG. 12, the vent stack 144 is in fluid
communication with a fume and heat containment chamber 123 within
the interior of the housing 122. The vent stack 144 is part of an
assembly including a hood 146. The hood 146 is mounted beneath the
vent stack 142 within the chamber 123.
[0062] Referring to FIGS. 13 and 14, a heating element 150 (e.g.,
an electric heating element (e.g., a coil, grid or other structure)
or other heating structure) is mounted in the chamber 123 adjacent
the bottom wall 124 of the housing 122. A heat reflector 152 (e.g.,
a porous ceramic disc/plate) is mounted beneath the heating element
150. Preferably, the reflector 152 is sufficiently porous to
readily allow air and ash to pass therethrough. In one embodiment,
the reflector 152 includes 5-25 pores per inch and has a thickness
in the range of 0.5-2 inches. The reflector 152 prevents radiant
heat loss into the container since air flow through the reflector
152 carries heat from the reflector upwardly to the diesel
particulate filter being serviced.
[0063] The heating element 150 and the reflector 152 are mounted
within a cylindrical first pipe section 200 having flanged upper
and lower ends. The flanged upper end allows an aftertreatment
device to be clamped in place (e.g., with v-band clamp 202) over
the heating element 150. The lower flanged end of the first pipe
section 200 is clamped to the upper flanged end of a second pipe
section 204 (e.g., with v-band clamp 206). The second pipe section
204 includes an enlarged diameter portion 208 connected to a
reduced diameter portion 210 by a conical diameter transition
portion 212. The second pipe section 204 is secured (e.g., welded
or fastened) to a rim 214 secured to the bottom wall 124 of the
cabinet 121. The reduced diameter portion 210 of the second pipe
section 204 projects downwardly below the bottom wall 124 and has a
flanged lower end.
[0064] The collection container 142 is clamped (e.g., with v-band
clamp 216) to the lower flanged end of the second pipe section 204.
The collection container 142 includes a main bin 143 having an open
top end covered by a lid 145. A pipe section 147 is mounted at the
center of the lid 145. The pipe section 147 extends though the lid
145 and has a flanged upper end that can be clamped to the lower
flanged end of the second pipe section 204. The lid 145 is
removable from the bin 143 to allow collected material to be
emptied from the bin 143.
[0065] A compressed air outlet 145 (e.g., a nozzle, hose, pipe, of
other structure) is positioned between the reflector 152 and the
container 142. For example, in FIG. 12, the outlet 45 is shown
connected to a compressed air line 122 that extends through an
opening 220 in the second pipe section 204. In the depicted
embodiment, the outlet 145 is configured to direct air in a
downward direction toward the container 142. In other embodiments,
the outlet may direct air upwardly toward the heating element or
laterally toward the side wall of the second pipe section 204.
[0066] It is preferred of the outlet 145 to be in fluid
communication with a source of compressed air 224 via the line 222.
A controller 226 controls the amount of air provided to the outlet
145. The flow can be controlled/metered to control the rate of
combustion at the aftertreatment device being serviced. In one
embodiment, the controller interfaces with a solenoid 228 that
opens and closes to provide pulses of air to the outlet 145. In one
embodiment, the source of compressed air has a pressure of at least
60 pounds per square inch (psi), or in the range of 60-100 psi, or
preferably about 90 psi. In another embodiment, flow rates
preferably in the range of 0.5-2.0 standard cubic feet per minute
(SCFM) are provided beneath the heating element during
regeneration. In still another embodiment, pulses having durations
in the range of 0.25-1 s, a pulse frequency of about 2-15 or 2-8
pulses per minute, and a flow rate in the range of 0.5-2.5 SCFM or
0.75-1.25 SCFM are provided beneath the heating element. It will be
appreciated that the above numerical information is provided for
illustration purposes only, and is not intended to limit the broad
inventive aspects of the present disclosure.
[0067] The pulses of air provide a number of functions. For
example, the air pulses impinge on the aftertreatment device
causing soot and ash packed on the device to be dislodged and to
fall into the container 42. The upward flow of air also carries and
distributes heat evenly through the aftertreatment device. By
controlling the air flow rate, the amount of oxygen supplied to the
aftertreatment device can also be controlled to control the core
temperature and combustion rate. In a preferred embodiment, the
high pressure air pulse can penetrate soot built-up on the diesel
particulate filter.
[0068] A blower 170 or fan is also mounted in the housing 122. A
wall 152 (see FIG. 11) separates the blower 150 from the chamber
123. A hose 154 provides fluid communication between the blower 150
and the interior of the main chamber. The blower 170 forces air
into the main chamber to facilitate venting the products of
combustion from the chamber. Further details regarding the device
120 are provided in PCT App. No. US 06/01850, filed Jan. 18, 2006
and entitled Apparatus for Combusting Collected Diesel Exhaust
Material from Aftertreatment Devices and Methods, which is hereby
incorporated by reference in its entirety.
[0069] In use of the system, the DPF 10 is removed from its
corresponding vehicle, and the front door 140 of the cabinet is
opened to provide access to the chamber 123. With the door 140
open, the DPF 10 can be mounted (e.g., clamped or otherwise
secured) on top of the heating element. Preferably, the DPF is
mounted with the inlet side facing downwardly and the outlet side
facing upwardly. Once the DPF is in place, the door 140 is closed
and the heating element is activated to heat the core of the DPF to
a temperature suitable for combusting soot and ash on the DPF
(e.g., 900-1500 F). During an initial warm-up period (e.g., about
20 minutes), the heating element is activated. During this warm up
period, it is preferred to not provide air pulses to the system so
that more uniform radiant heating is provided across the entire
face of the core being serviced. Uniform heating prevents
preferential air flow paths from developing in the DPF that may
interfere with the ability to uniformly regenerate the entire DPF.
After the warm-up period, the air outlet 45 begins to direct pulses
of air downwardly into the container 42 (e.g., at a pulse rate of
0.5 seconds on and 15 seconds off). The pulses of air reflect off
the container 142 and migrate upwardly through the heat reflector
152, the heating element 150 and the DPF mounted on the heating
element 150. The pulses of air assist in providing uniform
combustion temperatures across the entire volume of the DPF while
maintaining a controlled combustion. The pulses of air also assist
is dislodging soot and ash from the DPF during the combustion
process. The dislodged material falls downwardly from the DPF
through the heating element 150 and the heat reflector 152 and is
collected in the container 142. The container 142 is preferably
periodically disconnected from the cabinet to be emptied.
[0070] After the combustion process has been completed (e.g., about
3-5 hours), the heating element 150 turned off and the air flow is
increased during the cool-down. In one embodiment, the flow rate is
increased to at least 1.5 times the regeneration air flow rate. For
example, the pulse rate can be increased to 0.5 second on and 4-10
s or 7.5 to 10 seconds off). The cool-down period can often extend
for 2-3 hours. After the heating element and cabinet interior cool
to a predetermined temperature (e.g., 140 F), the front door 40 can
be opened to remove the regenerated DPF. Thereafter, another DPF
can be mounted on the heating element 150 and the process can be
repeated.
[0071] During heating, if the heating element fails (e.g., a
heating controller does not modulate), the solenoid fails (e.g.,
sticks open or closed), or the cabinet temperature exceeds a
predetermined temperature, the system can be programmed to abort
the regeneration cycle.
[0072] To make the process more efficient, the DPF 10, the pipe
sections 200, 204 and the container 142 can be covered with
insulating layers (e.g., heat shields, blankets, sheaths, etc.) For
example, FIG. 15 schematically shows an insulation sheath/blanket
250 wrapped around the DPF and the pipe sections 200, 204.
[0073] D. Implementation Method
[0074] FIG. 18 is a flow chart outlining certain aspects of the
present disclosure. At block 320 of FIG. 18, a customer is sold a
DPF for use on a low operating temperature vehicle. At the time of
the sale, the customer can be offered a service plan and service
schedule (i.e., a service contract) that details costs associated
with regenerating the DPF and also provides a regeneration
schedule. The service plan can be carried out by dealers or other
third parties. At the time of the sale, the customer can also be
provided with an option to upgrade the DPF to an on-board active
regeneration system in the event that the regeneration frequency
exceeds the amount set forth in the initial service plan.
[0075] At block 340 of FIG. 18, the regeneration service is
implemented to maintain the DPF. Off-board regeneration systems
such as a pulse regenerator, a thermal regenerator or other systems
can be used. Dealers affiliated with the DPF manufacturer can be
used to implement the service schedule.
[0076] At block 360 of FIG. 18, the regeneration frequency for the
DPF is monitored. If the frequency exceeds a predetermined amount,
or if the customer is otherwise dissatisfied with the DPF or the
regeneration schedule, the DPF can be converted to an active
system.
[0077] E. On-Board Active Regeneration System
[0078] FIGS. 19-21 illustrate a diesel engine exhaust treatment
device 420 equipped with on-board active regeneration equipment.
The device 420 can be used to treat exhaust from engines emitted
from diesel engines having duty cycles with average temperature
profiles greater than 200 degrees Celsius for less than 40 percent
of the operating cycle in the event that a system without on-board
active regeneration fails to meet customer needs. The exhaust
treatment device 420 includes an outer body 422 (e.g., a housing or
conduit) having an inlet end 424 and an outlet end 426. The exhaust
treatment device 420 also includes a diesel oxidation catalyst 428
(i.e., a catalytic converter/DOC) and a diesel particulate filter
430 (i.e., a DPF) positioned within the outer body 422. The DOC 428
is positioned upstream from the DPF 430. An on-board heater 432 is
positioned within the outer body 422 between the DOC 428 and the
DPF 430. The heater 432 is adapted to selectively provide heat for
regenerating the DPF 430. The exhaust treatment device 420 also
includes a power line 434 for providing electricity to the heater
432, a thermocouple 436 for measuring the temperature of the heater
432, a back pressure sensor 438 for sensing the back pressure
generated behind the DPF 430, and an air inlet 440 for providing
combustion air within the outer body 422 during regeneration of the
DPF 430. The exhaust treatment device 420 also includes a heat
shield 442 that surrounds the outer body 422 along a region
coinciding with the DOC 428, the heater 432 and the DPF 430. A
controller (e.g., a controller 406 provided at a shore station 440
as shown at FIGS. 22 and 23) can be used to control the
regeneration process. For example, the controller can be programmed
with a regeneration recipe (e.g., regeneration protocol) that sets
parameters such as regeneration heating temperatures, heating
durations, cool-down durations, and air flow rates during heating
and cool-down. The shore station 440 can also provide power to the
heater. Further details regarding the device 420 are provided at
PCT Publication No. WO06/96244, filed Jan. 18, 2006, which
application is hereby incorporated by reference in its
entirety.
[0079] F. Verification Process
[0080] The process for verifying emissions control technology with
CARB is set forth at Title 13, California Code of Regulations,
sections 2700 to 2710 (see attached as Exhibit 1). The verification
application includes information such as a definition of the
technology desired to be verified, a definition of the applicable
diesel engine characteristics, a definition of the type of
application, an indication the type of verification being sought
(e.g., level 1, 2 or 3), a description of the principles of
operation of the technology, a listing of emission reduction test
results, a listing of durability test results, and a field
demonstration.
[0081] In the present case, the technology desired to be verified
includes a DPF device in combination with the off-board
regeneration equipment such as an off-board heating device for
combustion soot on the DPF and/or an off-board air movement device
for blowing soot from the DPF. By way of example, the DPF device
can have the same structure as the DPF 10 previously described
herein. Also by way of example, the off-board regeneration
technology can include the off-board regeneration device 20 and/or
the off-board regeneration device 120. Of course, other
configurations of DPF's and off-board regenerating systems can also
be used.
[0082] It will be appreciated that a number of parameters can be
used to define the category/type of diesel engine being verified.
For example, the verification could apply to diesel engines
originally manufactured from model year 1994 through the
present.
[0083] The aspects of the present disclosure relate to obtaining
verification (e.g., level 2 or level 3 verification) for a DPF
system that does not include active, on-board regeneration
equipment used in an application having a duty cycle with an
average temperature profile greater than a predetermined
temperature (e.g., 240, 220 or 200 degrees Celsius) for less than a
certain percentage (e.g., 40 percent) of the engine operating
cycle.
[0084] To generate emissions production test results, durability
test results and a field demonstration, the DPF device will be
tested in accordance with the requirements specified by Title 13 of
the California Code of Regulations, Sections 2703, 2704 and 2705.
During the testing protocol, the DPF device will periodically be
regenerated using an off-board regeneration system. The preferred
duration between off-board regeneration events can be set forth in
the verification application. For example, off-board regeneration
can be conducted at set intervals (e.g., bimonthly), when a back
pressure sensor detects that a predetermined level of back pressure
is behind the DPF, or when the engine has operated a predetermined
number of hours since the last regeneration.
* * * * *