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EP 0 779 415 B1 |
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EUROPEAN PATENT SPECIFICATION |
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Mention of the grant of the patent: |
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23.05.2001 Bulletin 2001/21 |
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Date of filing: 06.11.1996 |
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Reactor chamber for catalytic cleaning of combustion exhausts
Reaktionskammer für die katalytische Reinigung von Verbrennungsgasen
Chambre de réaction pour le nettoyage catalytique d'échappements de combustion
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Designated Contracting States: |
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AT BE CH DE DK ES FI FR GB GR IE IT LI NL PT SE |
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Priority: |
11.12.1995 SE 9504439
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Date of publication of application: |
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18.06.1997 Bulletin 1997/25 |
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Proprietor: ABB FLÄKT AKTIEBOLAG |
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120 86 Stockholm (SE) |
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Inventors: |
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- Götmalm, Örjan
430 41 Kullavik (SE)
- Holmström, Per
426 79 Västra Frölunda (SE)
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Representative: Roth, Ernst Adolf Michael et al |
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GÖTEBORGS PATENTBYRA DAHLS
Sjöporten 4 417 64 Göteborg 417 64 Göteborg (SE) |
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References cited: :
EP-A- 0 158 625 DE-A- 1 476 629 US-A- 3 348 629 US-A- 3 648 803 US-A- 5 321 215
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EP-A- 0 615 777 DE-A- 4 327 562 US-A- 3 495 680 US-A- 3 780 826 US-A- 5 355 973
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Note: Within nine months from the publication of the mention of the grant of the European
patent, any person may give notice to the European Patent Office of opposition to
the European patent
granted. Notice of opposition shall be filed in a written reasoned statement. It shall
not be deemed to
have been filed until the opposition fee has been paid. (Art. 99(1) European Patent
Convention).
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FIELD OF THE INVENTION
[0001] The present invention refers to an exhaust conduit for cleaning exhausts of a Diesel
engine in a vessel, including a system for injection of a reagent into the combustion
exhausts of the engine, at least one reactor chamber for catalytic cleaning of said
exhausts, and at least one reactive silencer in communication with said exhaust conduit.
BACKGROUND OF THE INVENTION
[0002] When installing a reactor chamber according to above in a vessel, usually accommodations
must be made in order to clear the limited amount of available installation space.
It is known that a catalytic reactor having a number of layers of ceramic honeycomb
monolith blocks, display good sound absorbing properties, especially with regard to
high frequency sound. Thus, it is sometimes possible to dismount the conventional
silencer from the funnel shaft and replace it with a reactor chamber. However, you
risk the creation of interference within the exhaust system, for certain installation
applications and for certain operational conditions, so that certain sound frequencies
are increased instead of dampened. Thus, sound damping requirements result in that
an additional damper perhaps nevertheless has to be installed.
[0003] An exhaust conduit of the type described in the introductory part above is known
from EP 0 617 777A.
[0004] This publication discloses an apparatus for damping noise at an exhaust conduit belonging
to a Diesel engine, which conduit comprises a system for injection of a reagent into
the combustion exhausts of the engine, at least one reactor chamber for catalytic
cleaning of said exhausts, and at least one reactive silencer in communication with
said exhaust conduit, whereby the silencer comprises at least one resonance chamber
which is arranged concentric to a straight segment of the exhaust conduit and which
is connected to said said channel via at least one opening.
[0005] It is known to use a reactive silencer in the form of a quater wave resonator, a
so called Helmholtz resonator, in exhaust systems in order to dampen a certain low
frequency noise, e.g. within the range of 35-150 Hz. A conventionally designed quater
wave resonator is however comparatively space consuming and involve a clear risk for
collection of soot particles which may cause fire in the exhaust system and a gradual
deterioration of the function of the resonator.
[0006] An other type of reactive silencer is known from DE 14 76629A.
This publication discloses an apparatus for damping noise at an exhaust conduit, which
conduit comprises at least one reactive silencer in communication with said exhaust
conduit, whereby the silencer comprises at least one resonance chamber which is arranged
concentric to a straight segment of the exhaust conduit and which is connected to
the straight segment via at least one opening.
THE TECHNICAL PROBLEM
[0007] The object of the present invention is therefore to provide an apparatus for sound
damping which does not exhibit the above mentioned drawbacks, and which is simple
to integrate into an exhaust system comprising a catalytic reactor.
THE SOLUTION
[0008] For this object the invention is characterized in that the length of said silencer
being acoustically adapted to the wave length of the sound waves which are going to
be damped within a specific frequency range, the silencer comprises at least one resonance
chamber which is arranged concentric to a straight segment of the exhaust conduit
and which is connected to said exhaust conduit via at least one opening, and that
the at least one opening is located upstream to the reactor chamber.
[0009] Preferably, the opening is located so that it continually drains occurring soot particles
into the exhaust conduit. Alternatively, the opening may be provided with an acoustically
permeable filter which prevents soot particles from entering the resonance chamber.
[0010] According to a preferable embodiment of the invention, the resonance chamber is located
upstream the reactor chamber. This makes it possible to integrate the resonance chamber,
e.g. by means of a gasification unit for injection of the reagent, or a reagent mixer
unit.
[0011] Suitably, the radially inner wall of the resonance chamber is formed by the outer
wall of the exhaust conduit. This wall may be provided with a channel segment which
diverges conically downstream, said segment opening out into the reactor chamber and
causing a reduction in the pressure drop through the reactor.
[0012] Two or more resonance chambers may be coaxially located around the straight segment
with different lengths that are acoustically adapted to the wave length of the sound
waves which are going to be damped within different specific frequency ranges.
DESCRIPTION OF THE DRAWINGS
[0013] The invention will be described hereinafter with reference to embodiments that are
shown in the enclosed drawings, wherein
- Fig. 1
- schematically shows a Diesel engine with an exhaust system equipped with a silencer
apparatus according to the invention,
- Fig. 2
- shows in a larger scale a section through a silencer apparatus according to the invention,
along the line II-II in Fig. 3,
- Fig. 3
- shows a section along the line III-III in Fig. 2
- Fig. 4
- shows in a corresponding way as Fig. 2 a second embodiment of the silencer apparatus
according to the invention,
- Fig. 5
- schematically shows a gasification unit with a silencer apparatus according to a third
embodiment of the invention, and
- Fig. 6
- schematically shows a reactor chamber with a silencer apparatus according to a fourth
embodiment of the invention.
DESCRIPTION OF EMBODIMENTS
[0014] In the description, the expression "concentrically arranged" is used in order to
illustrate the location of the silencer apparatus with reference to the exhaust conduit
and the components included in the exhaust conduit: gasification unit, mixer unit
and reactor chamber. The expression "concentric" also include other sections than
circular, e.g. quadratic and triangular.
[0015] The installation diagrammatically shown in Fig. 1 comprises a Diesel engine 10 with
an exhaust conduit 11 which is connected to a gasification unit 12 for injection and
gasification of urea or some other reagent into the exhausts of the engine. The exhausts
are conducted from the gasification unit via a first mixer unit 13 and a second mixer
unit 14 which mixer units are arranged for providing an even distribution of the reagent
in the exhausts.
[0016] The mixer unit 14 is connected to a reactor chamber 15 which according to prior art
is provided with internal support surfaces for not shown honeycomb monoliths of a
ceramic material, which contribute to reduce for example contents of nitric oxide
in the exhausts. An outlet 16 from the reactor chamber 15 lead directly out into the
atmosphere.
[0017] As is illustrated by Fig. 2 and 3, the mixer unit 14 is built into a straight segment
17 of the pipe of the exhaust conduit which is provided with a number of openings
18 opening out into an otherwise closed resonance chamber 19 which is arranged concentrically
to the straight segment 17. The resonance chamber 19 forms by means of its outer walls
20 a reactive silencer the length of which is acoustically adapted to the wave length
of those sound waves which are going to be damped within a specific frequency range,
e.g. 50-150 Hz. The relations between the section areas for the resonance chamber
19 and the straight segment 17 determines the capacity for damping sound.
[0018] The openings 18 are located at the same level as the bottom edge of the resonance
chamber 19, so that they are able to drain occurring soot particles being transported
by the exhaust stream, back into the straight segment 17. By adapting the height of
the openings, the silencer frequency range may be broadened or concentrated.
[0019] Because the resonance chamber encloses the mixer unit 14, the chamber does not lead
to any actual lengthening of the exhaust system of the engine 10.
[0020] Because the radially inner wall of the resonance chamber is the same as the outer
wall 17 of the exhaust conduit, the gas in the resonance chamber will have substantially
the same temperature as the gas stream in the exhaust conduit, which is acoustically
advantageous. Besides, the design leads to a low level of material stress resulting
from thermal expansion.
[0021] Each honeycomb monolith is provided with a stocking 13 which extends along the vertical
sides and forms a seal against the adjacent blocks and the side walls 10.
[0022] Tests have proven that a silencer designed according to Fig. 2 and 3 provide a dampening
of about 10-20 dB(A) at a flow speed of 25-40 m/sec and a temperature range of 150-500
C°.
[0023] The exhaust conduit 17 displays a segment 17' which diverges in the direction of
flow, which segment opens out into the reactor chamber and provides a reduction of
the pressure fall through the reactor chamber.
[0024] Fig. 4 shows an embodiment of the invention where a further resonance chamber 21
is coaxially arranged around the exhaust conduit 17 inside the resonance chamber 19,
and communicates acoustically with the exhaust conduit 17 via openings 22 being located
downstream the openings 18. These openings 22 are also located so that they drain
soot particles back to the conduit 17. The resonance chamber 21 display a shorter
length than the resonance chamber 19 and is in that way acoustically adapted to wave
lengths of sound waves which are to be damped within another specific frequency range
than that which the resonance chamber 19 is designed for.
[0025] Fig. 5 shows a gasification unit 12 with spray nozzle 23 which is equipped with two
in series located resonance chambers 19, 21, essentially displaying the same sectional
area and length. Because the height of the openings 18 of the resonance chamber 19,
as seen in the direction of flow, are larger than the hight of the openings 22 of
the resonance chamber 21, the two resonance chambers 19, 21 may dampen sound within
different ranges of frequency.
[0026] Fig. 6 shows a reactor chamber 15 having four outer walls together forming a rectangular
chamber section. The reactor chamber comprises three levels of honeycomb monolith
blocks 24. Every one of the outer walls of the reactor chamber is so designed that
it forms a resonance chamber 19 which is connected via openings 18 to the exhaust
channel 11, which openings are located upstream the actual reactor chamber. Because
the individual resonance chambers 19 are identically designed, they may work together
as a single large resonance chamber. This means that the resonance chambers may be
made very small, so that they do not add to the dimensions of the reactor chamber
appreciably. Also, the resonance chambers 19 have an insulating effect around the
reactor chamber, so that the heat radiation to the environment may be reduced. Because
of this effect, the dimensions of the normal thermal insulation 25 of the reactor
chamber may be reduced, which also contributes to reducing the outer dimensions of
the reactor chamber. One of the four wall elements of the reactor chamber is preferably
dismountable, so that the honeycomb monolith blocks 24 may be exchanged.
[0027] By means of the apparatus according to the invention, a silencer unit is provided
which to a large extent facilitate installation of a plant catalytic reduction of
the exhausts from a Diesel engine, in particular within the limited amounts of space
which prevail within a vessel.
[0028] The invention is not limited to the above described embodiment. For example, the
resonance chamber may be located at another segment of the exhaust system than shown,
e.g. centrally around the gasification unit 12. It is possible to provide the apparatus
according to the invention with more than two resonance chambers.
1. An exhaust conduit (11) for cleaning exhausts of a Diesel engine in a vessel, including
a system (23, 12) for injection of a reagent into the combustion exhausts of the engine,
at least one reactor chamber (15) for catalytic cleaning of said exhausts, and at
least one reactive silencer (19-20/21; 22) in communication with said exhaust conduit,
characterized in that the length of said silencer (19-20; 21; 22) being acoustically adapted to
the wave length of the sound waves which are going the be damped within a specific
frequency range, the silencer (19-20; 21, 22) comprises at least one resonance chamber
(19; 21) which is arranged concentric to a straight segment (17) of the exhaust conduit
(11) and which is connected to said exhaust conduit (11) via at least one opening
(18; 22), and that the at least one opening is located upstream to the reactor chamber.
2. Exhaust conduit according to claim 1,
characterized in that a second straight segment of the exhaust conduit (11) is enclosed by a second
resonance chamber (19) and that the system for injection of the reagent is a gasification
unit (12).
3. Exhaust conduit according to claim 1,
characterized in that the opening (18; 22) is located so that it continually drains occurring soot
particles into the exhaust conduit (11).
4. Exhaust conduit according to claim 1,
characterized in that the straight segment of the exhaust conduit (11) which is enclosed by the
resonance chamber (19) comprises a reagent mixer unit (14).
5. Exhaust conduit according to any one of the preceding claims, characterized in that the straight segment (17) of the firstmentioned resonance chamber (19) is
provided with a channel segment (17') which diverges conically downstream, said segment
opening out into the reactor chamber (15).
6. Exhaust conduit according to claim 5,
characterized in that the straight segment of the resonance chamber (19) is formed by the outer
wall (17) of the exhaust conduit.
7. Exhaust conduit according to claim 1,
characterized in that two or more resonance chambers (19, 21) are coaxially located around the
straight segment (17) and having different lengths and being acoustically adapted
to the wave length of the sound waves which are going to be damped within different
specific frequency ranges.
8. Exhaust conduit according to claim 1,
characterized in that the opening (18, 22) is provided with an acoustically permeable filter.
1. Abgasleitung (11) für das Reinigen von Abgasen eines Dieselmotors in einem Hohlgefäß,
einschließend ein System (23; 12) für das Einspritzen eines Reagens in die Verbrennungsabgase
des Motors, zumindest einen Reaktionsraum (15) für das katalytische Reinigen der Abgase
und zumindest einen Reaktionsschalldämpfer (19-20; 21; 22), der mit der Abgasleitung
in Verbindung steht,
dadurch gekennzeichnet, daß die Länge des Schalldämpfers (19-20; 21; 22) schalltechnisch der Wellenlänge
der Schallwellen angepaßt ist, die innerhalb eines bestimmten Frequenzbereiches gedämpft
werden sollen, der Schalldämpfer (19-20; 21; 22) zumindest einen Resonanzraum (19,
21) umfaßt, der konzentrisch zu einem geraden Abschnitt (17) der Abgasleitung (11)
angeordnet ist und mit der Abgasleitung (11) über zumindest eine Öffnung (18; 22)
verbunden ist, und daß die zumindest eine Öffnung oberhalb des Reaktionsraumes angeordnet
ist.
2. Abgasleitung nach Anspruch 1,
dadurch gekennzeichnet, daß ein zweiter gerader Abschnitt der Abgasleitung (11) von einem zweiten Resonanzraum
(19) umschlossen wird und daß das System für das Einspritzen des Reagens eine Vergasungseinheit
(12) ist.
3. Abgasleitung nach Anspruch 1,
dadurch gekennzeichnet, daß die Öffnung (18; 22) so angeordnet ist, daß sie anfallende Rußpartikel fortlaufend
in die Abgasleitung (11) ableitet.
4. Abgasleitung nach Anspruch 1,
dadurch gekennzeichnet, daß der gerade Abschnitt der Abgasleitung (11), der von dem Resonanzraum (19) umschlossen
wird, eine Reagensmixereinheit (14) umfaßt.
5. Abgasleitung nach einem der vorhergehenden Ansprüche,
dadurch gekennzeichnet, daß der gerade Abschnitt (17) des erstgenannten Resonanzraumes (19) mit einem Kanalabschnitt
(17') versehen ist, der sich nach unten konisch erweitert, wobei der Abschnitt in
den Reaktionsraum (15) mündet.
6. Abgasleitung nach Anspruch 5,
dadurch gekennzeichnet, daß der gerade Abschnitt des Resonanzraumes (19) von der Außenwand (17) der Abgasleitung
gebildet wird.
7. Abgasleitung nach Anspruch 1,
dadurch gekennzeichnet, daß zwei oder mehr Resonanzräume (19,21) koaxial um den geraden Abschnitt (17) herum
angeordnet sind und verschiedene Längen aufweisen und schalltechnisch der Wellenlänge
der Schallwellen angepaßt sind, die innerhalb verschiedener bestimmter Frequenzbereiche
gedämpft werden sollen.
8. Abgasleitung nach Anspruch 1,
dadurch gekennzeichnet, daß die Öffnung (18, 22) mit einem schalldurchlässigen Filter versehen ist.
1. Conduite d'échappement (11) pour épurer les gaz d'échappement d'un moteur Diesel sur
un navire, comprenant un système (23, 12) pour l'injection d'un réactif dans les gaz
de combustion du moteur, au moins une chambre (15) de réacteur pour l'épuration catalytique
desdits gaz d'échappement, et au moins un silencieux à réaction (19-20/21 ; 22) en
communication avec ladite conduite d'échappement,
caractérisée en ce que, la longueur dudit silencieux (19-20 ; 21 ; 22) étant acoustiquement adaptée à la
longueur d'onde des ondes sonores qui vont être amorties dans une gamme de fréquences
spécifique, le silencieux (19-20 ; 21, 22) comprend au moins une chambre de résonance
(19 ; 21) qui est disposée de manière concentrique par rapport à un segment droit
(17) de la conduite d'échappement (11) et qui est raccordée à ladite conduite d'échappement
(11) par au moins une ouverture (18 ; 22), et en ce que ladite au moins une ouverture est située en amont de la chambre de réacteur.
2. Conduite d'échappement selon la Revendication 1, caractérisée en ce qu'un second segment droit de la conduite d'échappement (11) est entouré par une seconde
chambre de résonance (19) et en ce que le système d'injection du réactif est une unité de gazéification (12).
3. Conduite d'échappement selon la Revendication 1, caractérisée en ce que l'ouverture (18 ; 22) est située de telle sorte qu'elle draine en continu les particules
de suie se formant dans la conduite d'échappement (11).
4. Conduite d'échappement selon la Revendication 1, caractérisée en ce que le segment droit de la conduite d'échappement (11) qui est entouré par la chambre
de résonance (19) comprend une unité (14) de mélange du réactif.
5. Conduite d'échappement selon l'une quelconque des Revendications précédentes, caractérisée en ce que le segment droit (17) de la première chambre de résonance (19) mentionnée est muni
d'un segment de canal (17') qui diverge de manière conique en aval, ledit segment
débouchant dans la chambre de réacteur (15).
6. Conduite d'échappement selon la Revendication 5, caractérisée en ce que le segment droit de la chambre de résonance (19) est formé par la paroi extérieure
(17) de la conduite d'échappement.
7. Conduite d'échappement selon la Revendication 1, caractérisée en ce que deux chambres de résonance (19, 21) ou plus sont placées de manière coaxiale autour
du segment droit (17), qui ont des longueurs différentes et sont acoustiquement adaptées
à la longueur d'onde des ondes sonores qui vont être amorties dans des gammes de fréquences
spécifiques différentes.
8. Conduite d'échappement selon la Revendication 1, caractérisée en ce que l'ouverture (18, 22) est munie d'un filtre perméable aux sons.