U.S. patent application number 11/046042 was filed with the patent office on 2005-06-16 for ammonia storage and injection in nox control.
Invention is credited to Berriman, Lester P., Simons, Lionel S., Zabsky, John M..
Application Number | 20050129599 11/046042 |
Document ID | / |
Family ID | 29248801 |
Filed Date | 2005-06-16 |
United States Patent
Application |
20050129599 |
Kind Code |
A1 |
Berriman, Lester P. ; et
al. |
June 16, 2005 |
Ammonia storage and injection in NOx control
Abstract
A system is described for storing ammonia and injecting it into
the exhaust gas stream of an engine to reduce nitrogen oxides. The
ammonia is stored as a liquid mixture (70) of ammonia and water in
a container (50). In one system, the mixture passes through a hot
nozzle and is injected into an upstream portion of the exhaust gas
pipe.
Inventors: |
Berriman, Lester P.;
(Irvine, CA) ; Zabsky, John M.; (Santa Ana,
CA) ; Simons, Lionel S.; (Dana Point, CA) |
Correspondence
Address: |
LEON D. ROSEN
FREILICH, HORNBAKER & ROSEN
Suite 1220
10960 Wilshire Blvd.
Los Angeles
CA
90024
US
|
Family ID: |
29248801 |
Appl. No.: |
11/046042 |
Filed: |
January 28, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11046042 |
Jan 28, 2005 |
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10132552 |
Apr 24, 2002 |
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6852292 |
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Current U.S.
Class: |
423/235 |
Current CPC
Class: |
B01D 53/90 20130101;
F01N 2610/1453 20130101; B01D 53/86 20130101; F01N 2610/06
20130101; B01D 2251/2062 20130101; F01N 3/2066 20130101; Y02T 10/24
20130101; B01D 53/9413 20130101; F01N 2610/02 20130101; B01D 53/56
20130101; B01D 53/92 20130101; Y02T 10/12 20130101 |
Class at
Publication: |
423/235 |
International
Class: |
B01D 053/56 |
Claims
What is claimed is:
1. In an engine which includes means for combusting hydrocarbons in
air to produce work wherein said means also produces a stream of
exhaust gasses that contain nitrogen oxides, with the engine having
an exhaust conduit through which the exhaust gasses are passed
before being emitted into the atmosphere, the improvement
comprising: a container; a liquid mixture of ammonia and water in
said container, said container being stored away from said means
for combusting to minimize heating; an injector apparatus coupled
to said liquid in said container and to said exhaust conduit, said
injector apparatus being constructed to inject at least ammonia of
said mixture into said exhaust conduit.
2. The engine described in claim 1 wherein: said mixture of ammonia
and water in said container includes about 25% ammonia and about
75% water.
3. The engine described in claim 1 wherein: said injector apparatus
includes a tube that carries said liquid mixture, said tube lying
in a heat-exchange relationship with said exhaust conduit to use
the heat of the exhaust gasses to heat the liquid mixture of
ammonia and water.
4. The engine described in claim 1 wherein: said injector apparatus
includes a tube that carries said mixture of ammonia and water from
said source, and a nozzle coupled to said tube, said injector
apparatus being constructed to inject said mixture of ammonia and
water through said nozzle into said exhaust conduit.
5. In an engine which has an engine block with cylinders where
hydrocarbons are combusted in air to produce work, and which has an
exhaust conduit that carries away a stream of exhaust gasses that
contain nitrogen oxides, a source of ammonia and an injection
apparatus that is coupled to said source and that injects ammonia
into the conduit to reduce nitrogen oxides, the improvement
wherein: said source of ammonia comprises a container and a liquid
mixture of ammonia and water in said container, said container
being thermally isolated from said engine block and said exhaust
conduit. said injection apparatus is constructed to inject ammonia
and at least some of the water into said exhaust conduit.
6. The engine described in claim 5 wherein: said injector apparatus
includes a tube that carries said liquid mixture and that lies in a
heat-exchange relationship with said exhaust conduit to use the
heat of the exhaust gasses to heat the mixture of ammonia and
water.
7. The engine described in claim 5 wherein: said mixture of ammonia
and water in said container includes about 25% ammonia and 75%
water.
8. A method for reducing nitrogen oxide emission from an engine
that has an engine block with cylinders where hydrocarbons are
combusted in air to produce work, and which has an exhaust conduit
that carries away a stream of exhaust gasses that contain nitrogen
oxides, comprising: storing a liquid mixture of ammonia and water
in a container while thermally isolating the container from said
engine block and said exhaust conduit; passing said mixture from
said container to an injector apparatus, and injecting ammonia and
water into said exhaust conduit at a location downstream of said
engine block.
Description
CROSS-REFERENCE
[0001] This is a continuation-in-part of Ser. No. 10/132,552 filed
Apr. 24, 2002.
BACKGROUND OF THE INVENTION
[0002] In our earlier U.S. Pat. Nos. 5,224,346 and 5,992,141, we
described experiments which showed that the amount of nitrogen
oxides (NO and NO.sub.2), or NOx in engine exhaust gasses can be
reduced by injecting ammonia (NH.sub.3) which reacts with nitrogen
oxides to produce nitrogen and water. One practical problem is how
to store ammonia that is to be injected into the exhaust gas
stream. Ammonia can be stored as a liquid, at a pressure of about
150 psi, with the ammonia turning into gas when removed from the
container and its pressure reduced. It is often undesirable to
store ammonia under considerable pressure because of the danger of
an explosion and the possibility of rapid leakage of ammonia.
Another way for storing ammonia is to store it as urea (H.sub.2 NCO
NH.sub.2) as in a solution with water, and inject it into the
exhaust gas stream. However, it can take a longer time for urea to
react with nitrogen oxides and turn them into nitrogen and water,
than ammonia. Since the temperature of the exhaust gas stream very
rapidly drops as the exhaust gasses move through the exhaust pipe
into the atmosphere, it is desirable that the reactions occur very
rapidly so they can occur at the high temperatures that exist in
and near the exhaust gas manifold so that a high proportion of the
injected material (ammonia or urea) can react with the nitrogen
oxides. A system that enabled the storage of ammonia (NH.sub.3)
without requiring storage under high pressure, so that the ammonia
could be directly injected into hot exhaust gasses and rapidly
react with nitrogen oxides, would be of value.
SUMMARY OF THE INVENTION
[0003] In accordance with one embodiment of the present invention,
a system is provided for storing and injecting ammonia into the
exhaust gasses of an engine, which enables safe storage of the
ammonia and the injection of ammonia into the exhaust gasses for
rapid reaction with nitrogen oxides. The ammonia is stored as a
liquid mixture of ammonia and water. The ammonia is preferably
stored as a mixture of between 30 and 70 grams of ammonia per 100
grams of water. The liquid mixture is drawn off through a tube
leading from the container. In one system, the tube is heated by
the exhaust gasses and the mixture of ammonia and water is injected
directly into the exhaust gasses.
[0004] The novel features of the invention are set forth with
particularity in the appended claims. The invention will be best
understood from the following description when read in conjunction
with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a simplified schematic view of an engine, with
pollution reduction apparatus of the present invention installed
therein.
[0006] FIG. 2 is a graph showing variation of the saturation mass
of ammonia in water as a function of temperature.
[0007] FIG. 3 is a graph similar to that of FIG. 2, but showing
variation of the saturation percent (by mass) of ammonia in a
mixture of ammonia and water, as a function of temperature.
[0008] FIG. 4 is an enlarged view of a portion of the system of
FIG. 1, showing separation of a liquid mixture of ammonia and water
into gaseous ammonia and water vapor.
[0009] FIG. 5 is a sectional-view showing a portion of the
apparatus of FIG. 2.
[0010] FIG. 6 is a simplified schematic view of a system of another
embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0011] FIG. 1 illustrates a system 10 of the present invention,
wherein an engine 12 has cylinders in which fuel and air are
combusted to turn a crankshaft 14. The combustion produces hot
exhaust gasses that are passed through an exhaust conduit 16 into
the atmosphere. The exhaust conduit includes a manifold 20 that is
connected to a few cylinders to collect the exhaust gasses
therefrom. A catalytic convertor 22 that lies along the exhaust
conduit, is widely used in vehicle engines to reduce pollution.
[0012] FIG. 1 shows an ammonia injection system 30 that includes a
source 32 of ammonia. An injector apparatus 33 includes a metering
valve 34, tube 36 with tube portion 62, and an injection nozzle at
40. The metering valve 34 passes ammonia from the source through a
tube 36 to an ammonia injection location 40 where ammonia is
injected into the exhaust conduit 16 to mix with hot exhaust
gasses. The location 40 lies in or close to the exhaust gas
manifold 20, so the ammonia encounters very hot exhaust gasses
(usually over 1100.degree. F. at high engine loads) to promote the
reaction of ammonia and the exhaust gasses and thereby reduce
nitrogen oxides.
[0013] In accordance with the present invention, the source 32 for
ammonia is a container 50 that contains a mixture 70 of ammonia in
water. FIG. 2 includes a graph 52 showing the mass of ammonia, at
saturation in a solution that contains 100 grams of water, at
different temperatures. FIG. 3 contains a similar graph 54 that
shows the saturation percent, by mass, of ammonia in a solution of
ammonia and water. It can be seen that the percent ammonia (by
mass), ranges from about 47% at 32.degree. F. through 33% ammonia
at 72.degree. F., down to 0% at 212.degree. F. As a practical
matter, applicant can vary the percent ammonia according to the
weather, but prefers to establish about 25% ammonia, so the ammonia
will not go out of the mixture unless the temperature of the
mixture increases beyond about 105.degree. F. Also, the container
is kept away from the engine and is cooled by air, to avoid heating
the container. If the container should be heated so that gaseous
ammonia begins to accumulate under pressure and the pressure
exceeds a certain limit (e.g. 2 psi), a relief valve 60 (FIG. 1)
will slowly vent the gaseous ammonia into the atmosphere. The rate
of ammonia vented is very small, so it is not dangerous. A check
valve 61 (FIG. 1) can admit air to avoid a vacuum above the liquid
when the liquid is withdrawn.
[0014] The tube 36 that carries the ammonia-water mixture has a
portion 62 that is wrapped about the exhaust conduit 16, to rapidly
heat the ammonia-water mixture that passes through the tube 36 to
the injection location 40.
[0015] FIG. 4 indicates how the ammonia may be separated from the
water at a separation station 68, before injection of the ammonia
into the exhaust conduit. Initially, the mixture 70 at a
temperature such as 75.degree. F. passes through the tube 36, to
the tube portion 62 that is in a heat-exchange relationship with
the exhaust conduit, so material within the tube portion 62 is
rapidly heated. With the initial percent of ammonia being about
25%, the ammonia is not released as a gas until the mixture reaches
the location 72 which is at about 105.degree. F. Progressively more
ammonia is released as the temperature of the mixture progressively
increases. At the location 74, the mixture has a temperature of
about 200.degree. F., and only a few percent of ammonia remains in
the mixture. The rest of the ammonia, indicated at 80, continues
along a tube end portion 82, that carries the ammonia along a path
83 to an injector shown at 84 in FIG. 4. The injector can be of the
type described in our earlier U.S. Pat. No. 5,992,141, which
results in rapid heating of the gaseous ammonia prior to its
injection into the very high temperature exhaust gasses, to
activate the ammonia (break down some of the ammonia into its
constituents) for injection into the exhaust gas stream.
[0016] The liquid 90 shown in FIG. 4 which moves along a path 91,
contains only a very small percent of ammonia, and is disposed of.
One way to dispose of it, indicated in FIG. 1, is to carry the
liquid with a very small percent of ammonia along a tube 92 for
injection at 94 into the exhaust pipe. The location 94 is a
location where the temperature of the exhaust gasses have been
reduced to perhaps 250.degree. F., in which case the small quantity
of injected water will evaporate and become part of the exhaust gas
stream that is admitted into the atmosphere. It should be noted
that small pumps may be located in the injection system 30 where
pressure increases are required. In FIG. 1, the metering valve 34
is controlled by a circuit 100 that also controls a fuel injector
102 that injects fuel from a fuel line 104 into the engine
cylinders. As discussed in my earlier U.S. Pat. No. 5,992,141, this
varies the amount of ammonia in accordance with the load on the
engine, to more effectively neutralize nitrogen oxides.
[0017] FIG. 6 illustrates a system 110 which includes a container
112 that contains the mixture 70 of ammonia (NH.sub.3) and water
(HO.sub.2). Other ingredients can be added to the mixture 70, but
applicant prefers that most of the mixture be water and ammonia.
The ammonia is required to reduce nitrogen oxides and the water is
useful to retain the ammonia and is a liquid that is easily
disposed of because of its benign characteristics. In the system
110 of FIG. 6, applicant passes the mixture 70, which may have
perhaps 25% ammonia by weight, and water, directly through a nozzle
84 that lies in the exhaust gas conduits 16, at an upstream
location near or in the exhaust manifold. This system has the
disadvantage that water is injected with the ammonia into the hot
exhaust gasses, and tends to cool the exhaust gasses more rapidly.
However, the amount of water and ammonia is very small, so the
cooling effect of the water is very small. This system also has the
disadvantage that the ammonia is heated only moderately by the hot
nozzle prior to injection into the exhaust gas stream, so only a
low percent of the ammonia is activated to break down the ammonia
into its components (NH.sub.2 and NH) prior to injection. However,
the simplicity of the system 110 can make it useful even if its
effectiveness in reducing nitrogen oxides is not as great.
[0018] Thus, the invention provides a system for reducing nitrogen
oxides in the exhaust gasses of an engine by the injection of
ammonia into the exhaust gasses, which facilitates storage of the
ammonia. The ammonia is stored as a mixture of ammonia and water
(other liquids can be present), with the percent of ammonia
preferably being between about 15% and 50% to avoid the generation
of pressured ammonia gas. In one system, the mixture is heated to
convert most of the ammonia into its gaseous state and separate it
from the water that still remains liquid, and with the gaseous
ammonia being further heated to activate at least a portion of it
and then being injected into the hot exhaust gasses near or in the
exhaust gas manifold. In a simpler system, the ammonia and water
mixture 15 flowed towards the exhaust gas conduit and both ammonia
and water are injected into the exhaust conduit.
[0019] Although particular embodiments of the invention have been
described and illustrated herein, it is recognized that
modifications and variations may readily occur to those skilled in
the art, and consequently, it is intended that the claims be
interpreted to cover such modifications and equivalents.
* * * * *