U.S. patent application number 12/836202 was filed with the patent office on 2012-01-19 for method for heating solid ammonia to release gaseous ammonia in exhaust aftertreatment system.
This patent application is currently assigned to International Engine Intellectual Property Company, LLC. Invention is credited to Gregory A. Griffin, Timothy Yoon.
Application Number | 20120011830 12/836202 |
Document ID | / |
Family ID | 45465817 |
Filed Date | 2012-01-19 |
United States Patent
Application |
20120011830 |
Kind Code |
A1 |
Griffin; Gregory A. ; et
al. |
January 19, 2012 |
METHOD FOR HEATING SOLID AMMONIA TO RELEASE GASEOUS AMMONIA IN
EXHAUST AFTERTREATMENT SYSTEM
Abstract
A method for heating solid ammonia (NH.sub.3) in a main unit
(12) to deliver gaseous ammonia into the exhaust gas (EG)
downstream of an engine (16) includes the steps of diverting at
least a portion of the exhaust gas from the exhaust gas passageway
(14), fluidly communicating the exhaust gas on a delivery line (28)
from the exhaust gas passageway to the main unit, heating the solid
ammonia with the exhaust gas, and fluidly communicating the exhaust
gas on a return line (30) from the main unit to the exhaust gas
passageway.
Inventors: |
Griffin; Gregory A.;
(Glendale Heights, IL) ; Yoon; Timothy;
(Northbrook, IL) |
Assignee: |
International Engine Intellectual
Property Company, LLC
Warrenville
IL
|
Family ID: |
45465817 |
Appl. No.: |
12/836202 |
Filed: |
July 14, 2010 |
Current U.S.
Class: |
60/277 ; 60/288;
60/303 |
Current CPC
Class: |
F01N 3/2066 20130101;
Y02T 10/12 20130101; F01N 2900/1806 20130101; F01N 2610/06
20130101; F01P 2060/18 20130101; Y02T 10/24 20130101 |
Class at
Publication: |
60/277 ; 60/303;
60/288 |
International
Class: |
F01N 11/00 20060101
F01N011/00; F01N 9/00 20060101 F01N009/00; F01N 3/10 20060101
F01N003/10 |
Claims
1) A method for heating solid ammonia (NH.sub.3) in a main unit to
deliver gaseous ammonia into exhaust gas downstream of an engine,
the method comprising: providing engine coolant that is dedicated
only to heating the solid ammonia; heating the dedicated engine
coolant at a heater; fluidly communicating the engine coolant on a
delivery line from the heater to the main unit; heating the solid
ammonia with the heated engine coolant; and fluidly communicating
the engine coolant on a return line from the main unit to the
heater.
2) The method of claim 1 wherein the heated engine coolant heats
the solid ammonia to a temperature of at least about 150-degrees
Celsius for the eighth molecule of gaseous ammonia to be released
from the solid ammonia.
3) The method of claim 1 wherein the heater is a thermo-electric
heater that uses the Peltier effect to heat the engine coolant.
4) The method of claim 1 wherein the heater is an electric
heater.
5) The method of claim 1 further comprising storing the solid
ammonia inside an NH3 cartridge that is disposed inside of the main
unit.
6) The method of claim 1 further comprising controlling the
temperature of the engine coolant with a control unit.
7) The method of claim 1 further comprising sensing the temperature
of the engine coolant with a sensor.
8) A method for heating solid ammonia (NH.sub.3) in a main unit to
deliver gaseous ammonia into exhaust gas in an exhaust gas
passageway downstream of an engine, the method comprising:
diverting at least a portion of the exhaust gas from the exhaust
gas passageway; fluidly communicating the exhaust gas on a delivery
line from the exhaust gas passageway to the main unit; heating the
solid ammonia with the exhaust gas; and fluidly communicating the
exhaust gas on a return line from the main unit to the exhaust gas
passageway.
9) The method of claim 8 wherein the heated exhaust gas heats the
solid ammonia to a temperature of at least about 150-degrees
Celsius for the eighth molecule of gaseous ammonia to be released
from the solid ammonia.
10) The method of claim 8 further comprising the step of diverting
the exhaust gas downstream of an aftertreatment device.
11) The method of claim 10 further comprising the step of returning
the exhaust gas downstream of the aftertreatment device.
12) The method of claim 8 further comprising storing the solid
ammonia inside an NH3 cartridge that is disposed inside of the main
unit.
13) A method for heating solid ammonia (NH.sub.3) in a main unit to
deliver gaseous ammonia into exhaust gas downstream of an engine,
the method comprising: providing at least one of engine oil and
transmission oil; fluidly communicating the oil on a delivery line
from the at least one of the engine and the transmission to the
main unit; heating the solid ammonia with the heated oil; and
fluidly communicating the oil on a return line from the main unit
to the at least one of the engine and the transmission.
14) The method of claim 13 further comprising storing the solid
ammonia inside an NH3 cartridge that is disposed inside of the main
unit.
15) The method of claim 13 further comprising controlling the
temperature of the oil with a control unit.
16) The method of claim 13 further comprising sensing the
temperature of the oil with a sensor.
17) A method for heating solid ammonia (NH.sub.3) to deliver
gaseous ammonia into exhaust gas downstream of an engine, the
method comprising: embedding an electric coil into the solid
ammonia; heating the electric coil with an electrical heater; and
attaching the electric coil to the electric heater with at least
one wire.
18) The method of claim 17 further comprising embedding the
electric coil inside of an NH.sub.3 cartridge.
19) The method of claim 17 further comprising controlling the
temperature of the embedded coil with a control unit.
20) The method of claim 17 further comprising sensing the
temperature of the solid ammonia with a sensor.
Description
BACKGROUND
[0001] Embodiments described herein relate to methods for heating a
cartridge of ammonia salts to release ammonia into an exhaust
aftertreatment system.
[0002] Diesel engine combustion results in the formation of
nitrogen oxides, (NO.sub.x), in the exhaust gas. An aftertreatment
system is used to reduce oxides of Nitrogen (NO.sub.x) emitted from
the diesel engine. Nitrogen oxides can be reduced by ammonia
(NH.sub.3), which is injected into the exhaust gas stream, yielding
N.sub.2, H.sub.2O and CO.sub.2.
[0003] Typically, NH.sub.3 is molecularly bonded to a solid host
salt that is placed inside of a vessel called a main unit. The main
unit is heated by hot engine coolant that is circulated around the
main unit in a surrounding heating mantle. When heated, the host
salt releases NH.sub.3 molecules as gas, and the gaseous NH.sub.3
is delivered to the exhaust gas stream where the nitrogen oxides
are reduced.
[0004] The engine needs to provide an adequate amount of thermal
energy for the host salt to release the gaseous NH.sub.3. Some
engines may need to operate for a period of time to heat up the
coolant. To decrease the NH.sub.3 delivery time, an electrically
heated start-up unit is often used to provide NH.sub.3 to the
exhaust gas stream until the engine coolant is hot enough to
provide adequate thermal energy to the main unit.
[0005] Even when there is sufficient thermal energy for a reaction
to occur, often only seven of the eight NH.sub.3 molecules are
released from the host salt because the engine coolant does not
have adequate thermal energy to remove the eighth molecule. The
eighth molecule often goes unused.
[0006] Some engines may not provide sufficient thermal energy for
the exothermic NH.sub.3 reaction to occur at all. Further, with
developments in engine technology directed at increased efficiency,
future engines may not run hot enough to support the exothermic
NH.sub.3 reaction.
[0007] Additionally, diverting engine coolant from other engine
systems can cause a flow imbalance in the other engine systems. A
flow imbalance of engine coolant can lead to engine system
failures.
SUMMARY
[0008] A method for heating solid ammonia (NH.sub.3) in a main unit
to deliver gaseous ammonia into the exhaust gas downstream of an
engine includes the steps of providing engine coolant that is
dedicated only to heating the ammonia, heating the dedicated engine
coolant at a heater, and fluidly communicating the engine coolant
on a delivery line from the heater to the main unit. The method
also includes the steps of heating the solid ammonia with the
heated engine coolant, and fluidly communicating the engine coolant
on a return line from the main unit to the heater.
[0009] Another method for heating solid ammonia (NH.sub.3) to
deliver gaseous ammonia into the exhaust gas downstream of an
engine includes the steps of diverting at least a portion of the
exhaust gas from the exhaust gas passageway, fluidly communicating
the exhaust gas on a delivery line from the exhaust gas passageway
to the main unit, heating the solid ammonia with the exhaust gas,
and fluidly communicating the exhaust gas on a return line from the
main unit to the exhaust gas passageway.
[0010] In another method for heating ammonia (NH.sub.3) in a main
unit to deliver gaseous ammonia into exhaust gas downstream of an
engine, the method includes the steps of providing engine oil or
transmission oil, fluidly communicating the oil on a delivery line
from the engine or the transmission to the main unit, and heating
the solid ammonia with the heated oil. The method also includes the
step of fluidly communicating the oil on a return line from the
main unit to the engine or the transmission.
[0011] Another method for heating solid ammonia (NH.sub.3) to
deliver gaseous ammonia into exhaust gas downstream of an engine
includes the steps of embedding an electric coil into the solid
ammonia, heating the electric coil with an electrical heater, and
attaching the electric coil to the electric heater with at least
one wire.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a schematic showing the method of heating ammonia
in a main unit with diverted exhaust gas.
[0013] FIG. 2 is a schematic showing the method of heating ammonia
in the main unit with engine oil or transmission oil.
[0014] FIG. 3 is a schematic showing the method of heating ammonia
in the main unit with dedicated coolant and an electric heater.
[0015] FIG. 4 is a schematic showing the method of heating ammonia
in the main unit with dedicated coolant and a Peltier module.
[0016] FIG. 5 is a schematic showing the method of heating ammonia
in the main unit with embedded electrical coils.
DETAILED DESCRIPTION
[0017] Referring to FIGS. 1-5, a method of heating a main unit 12
for delivering gaseous ammonia (NH.sub.3) into an exhaust gas
passageway 14 of a diesel engine 16 is indicated generally at 10,
110, 210, 310 and 410. The exhaust gas (EG) flows from the engine
16 to an outlet 18 through the exhaust gas passageway 14 in the
direction indicated by the arrow. One or more aftertreatment
devices 20 may be disposed on the exhaust gas passageway 14 between
the engine 16 and the outlet 18 to treat the exhaust gas EG before
being emitted at the outlet.
[0018] When the engine 16 combusts diesel, nitrogen oxides form and
are released with the exhaust gas (EG). Nitrogen oxides, NOx, are a
pollutant that are reduced in the aftertreatment system by gaseous
ammonia (NH.sub.3) resulting in the emission of less harmful
nitrogen, N.sub.2, water, H.sub.2O, and carbon dioxide, CO.sub.2.
The NH.sub.3 is stored in a solid state in a NH.sub.3 cartridge 22
inside of the main unit 12. When there is sufficient thermal
energy, an exothermic reaction occurs, releasing gaseous NH.sub.3
that can be delivered to the exhaust gas.
[0019] The delivery of NH.sub.3 may be implemented by software on
the vehicle, such as at a control unit 24, however other
controllers are possible. At least one sensor 26 may sense the
NH.sub.3 gas outlet pressure at or near the NH.sub.3 cartridge 22,
such as at the outlet or downstream of the main unit 12. If the
sensor 26 senses that the system requires NOx reduction, the
control unit 24 may increase the amount of thermal energy from an
alternative source of thermal energy, as will be discussed below.
The system will dose NH.sub.3 to the exhaust passageway 14 as long
as the main unit 12 NH.sub.3 outlet pressure is in the range of
about 1.8-2.5 bar abs. The exhaust gas EG pressure is typically in
the range of 1.4-1.5 bar abs.
[0020] The methods 10, 110, 210, 310 and 410 of FIGS. 1-5 all use
alternative sources of thermal energy to heat the main unit 12 as
compared to the conventional source, which is engine coolant that
is shared with other engine systems to heat the main unit 12.
Although the following description will be directed to a method for
heating the main unit 12 in a vehicle aftertreatment system, the
method 10, 110, 210, 310 and 410 of FIGS. 1-5 can be used with any
diesel engine 16 that emits NOx.
[0021] Referring to FIG. 1 and the method of heating 10, the
alternative source of thermal energy is exhaust gas EG diverted
from the exhaust gas passageway 14. The exhaust gas EG may be
diverted downstream of the aftertreatment device 20 so that the
exhaust gas is less corrosive and free of unburned hydrocarbons and
other particulate matter relative to the exhaust gas upstream of
the aftertreatment device. The exhaust gas EG flows through a
delivery line 28 to the main unit 12.
[0022] At the main unit 12, the exhaust gas EG surrounds the
NH.sub.3 cartridge 22 and heats the ammonia salt contained in the
cartridge. The temperature of the NH.sub.3 cartridge 22 may exceed
the minimum temperature to release gaseous ammonia NH.sub.3, and
may be about 150-degrees Celsius, which is sufficient thermal
energy to release the eighth molecule of gaseous NH.sub.3 from the
ammonia salt. After circulating around the NH.sub.3 cartridge 22,
the exhaust gas EG is cooled and flows back to the exhaust gas
passageway 14 on a return line 30. The gaseous NH.sub.3 may also
flow to the exhaust gas passageway 14 on the return line 30, or
alternatively, may be delivered to the exhaust gas passageway on a
separate NH.sub.3 line 31. Using exhaust gas EG as the thermal
source, engine coolant systems are not affected.
[0023] Referring to FIG. 2, the method of heating 110 employs
engine oil or transmission oil (oil) as the alternative source of
thermal energy. The heated oil is delivered from the engine or
transmission 16 and flows through a delivery line 128 to the main
unit 12, where the oil flows around the NH.sub.3 cartridge 22. The
oil heats the ammonia salt contained in the NH.sub.3 cartridge 22
to release gaseous ammonia. The cooled oil flows from the main unit
12 back to the engine or transmission 16 on the return line 130.
The gaseous ammonia NH.sub.3 released from the NH.sub.3 cartridge
22 is delivered to the aftertreatment device 20 on the exhaust gas
passageway 14.
[0024] It is possible that transmission oil may be used in
applications where the engine is not hot enough to provide adequate
thermal energy, or where diverting engine coolant may lead to
system imbalances. Further, since oil is used as the thermal
source, engine coolant systems are not affected by the method 110
of heating the NH.sub.3 cartridge 22. It is possible that both
engine oil and transmission oil can be used.
[0025] Referring now to the method of heating 210 of FIG. 3, the
alternative source of energy is coolant (CL) provided on a
dedicated coolant circuit. The coolant CL is coolant that is not
used for other engine systems, but is coolant that is used only to
heat the NH.sub.3 cartridge. The dedicated coolant CL is not
connected to the engine's 16 coolant circuit, however the hardware
to circulate the coolant may be mounted on the engine, the chassis,
or anywhere else. The coolant CL is heated at a heater 232, such as
an electrical heater, and from the heater, the coolant is in fluid
communication with the main unit 12 on a delivery line 228.
Temperatures may exceed about 150-degrees Celsius at the main unit
12, which may release the eighth molecule of NH.sub.3 from the
NH.sub.3 cartridge 22. The cooled coolant CL flows back to the
heater 232 on a return line 230. The gaseous NH.sub.3 released from
the cartridge 22 is delivered to the exhaust gas passageway 14 on
line 31.
[0026] The method of heating 310 of FIG. 4 employs dedicated engine
coolant (CL) that is heated thermoelectrically. The coolant CL is
coolant that is not used for other engine systems, but is used only
to heat the NH.sub.3 cartridge. The coolant CL is heated
thermoelectrically at a thermo-module 332, for example a
thermo-module that uses the Peltier Effect to heat the coolant CL.
The heated coolant CL is in fluid communication with the main unit
12 on a delivery line 328 from the thermo-module 332 to the main
unit. The heated coolant provides sufficient thermal energy for
gaseous ammonia to be released and to be delivered to the exhaust
gas passageway 14. A return line 330 provides the fluid
communication of the coolant CL from the main unit 12 back to the
thermo-module 332.
[0027] Referring now to FIG. 5, the method of heating 410 employs
electrical coils 434 embedded in the host salt of the NH.sub.3
cartridge 22. The electrical coils 434 are electrically connected
with at least two wires 436, 438 to an electric heating source 432.
The embedded coils 434, heated by the heating source 432, provide
sufficient thermal energy to release gaseous ammonia NH.sub.3,
which is deliverable to the exhaust gas passageway 14.
[0028] The methods of FIGS. 1-5 may allow the size of the main unit
12 to be reduced since the alternative sources of thermal energy
may be more efficient than the conventional engine coolant.
Further, the methods of FIGS. 1-5 may release the eighth molecule
of the NH.sub.3 to which can be used to convert NOx. Further still,
the start-up unit that is often used with the conventional engine
coolant can be eliminated.
* * * * *