WO2012164000A2 - Dispositif de purification des gaz d'échappement pour la réduction des oxydes d'azote dans un flux de gaz d'échappement de moteurs à combustion interne - Google Patents

Dispositif de purification des gaz d'échappement pour la réduction des oxydes d'azote dans un flux de gaz d'échappement de moteurs à combustion interne Download PDF

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Publication number
WO2012164000A2
WO2012164000A2 PCT/EP2012/060215 EP2012060215W WO2012164000A2 WO 2012164000 A2 WO2012164000 A2 WO 2012164000A2 EP 2012060215 W EP2012060215 W EP 2012060215W WO 2012164000 A2 WO2012164000 A2 WO 2012164000A2
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Prior art keywords
exhaust gas
catalyst
purification device
exhaust
gas purification
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PCT/EP2012/060215
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German (de)
English (en)
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WO2012164000A3 (fr
Inventor
Torsten Schlicht
Dirk Dombrowski
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AKRETIA GmbH
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AKRETIA GmbH
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Publication of WO2012164000A3 publication Critical patent/WO2012164000A3/fr
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion
    • F01N3/206—Adding periodically or continuously substances to exhaust gases for promoting purification, e.g. catalytic material in liquid form, NOx reducing agents
    • F01N3/2066—Selective catalytic reduction [SCR]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9404—Removing only nitrogen compounds
    • B01D53/9409—Nitrogen oxides
    • B01D53/9413—Processes characterised by a specific catalyst
    • B01D53/9418—Processes characterised by a specific catalyst for removing nitrogen oxides by selective catalytic reduction [SCR] using a reducing agent in a lean exhaust gas
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9404—Removing only nitrogen compounds
    • B01D53/9409—Nitrogen oxides
    • B01D53/9431—Processes characterised by a specific device
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion
    • F01N3/2006—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating
    • F01N3/2033—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating using a fuel burner or introducing fuel into exhaust duct
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/28—Construction of catalytic reactors
    • F01N3/2803—Construction of catalytic reactors characterised by structure, by material or by manufacturing of catalyst support
    • F01N3/2832—Construction of catalytic reactors characterised by structure, by material or by manufacturing of catalyst support granular, e.g. pellets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/20—Reductants
    • B01D2251/206—Ammonium compounds
    • B01D2251/2062—Ammonia
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/207—Transition metals
    • B01D2255/20715—Zirconium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/207—Transition metals
    • B01D2255/20738—Iron
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/207—Transition metals
    • B01D2255/20753—Nickel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/207—Transition metals
    • B01D2255/20784—Chromium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/209—Other metals
    • B01D2255/2092—Aluminium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/50—Zeolites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/911—NH3-storage component incorporated in the catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/40—Nitrogen compounds
    • B01D2257/404—Nitrogen oxides other than dinitrogen oxide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/70—Organic compounds not provided for in groups B01D2257/00 - B01D2257/602
    • B01D2257/702—Hydrocarbons
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N2240/00—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being
    • F01N2240/14—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being a fuel burner
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N2260/00—Exhaust treating devices having provisions not otherwise provided for
    • F01N2260/04—Exhaust treating devices having provisions not otherwise provided for for regeneration or reactivation, e.g. of catalyst
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N2330/00—Structure of catalyst support or particle filter
    • F01N2330/08—Granular material
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N2330/00—Structure of catalyst support or particle filter
    • F01N2330/22—Metal foam
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N2590/00—Exhaust or silencing apparatus adapted to particular use, e.g. for military applications, airplanes, submarines
    • F01N2590/02—Exhaust or silencing apparatus adapted to particular use, e.g. for military applications, airplanes, submarines for marine vessels or naval applications
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/02—Adding substances to exhaust gases the substance being ammonia or urea
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the invention relates to an exhaust gas purification device with a bed of catalyst elements for the reduction of nitrogen oxides in the exhaust gas flow of an internal combustion engine.
  • a variety of catalysts have been proposed in the past to purify environmentally relevant substances such as nitrogen oxides in various oxidation states (NO, NO 2 , N 2 O 4 , N 2 O 5, and N 2 O) emitted from internal combustion engines , These are controlled or uncontrolled catalysts, oxidation catalysts, three-way conversion catalysts (TWC catalysts), NO x storage catalysts and SCR (selective catalytic reduction) catalysts.
  • nitrogen oxides (NO x ) are among the limited exhaust gas components used in shipping, which are produced during combustion processes and whose permitted emissions are continually reduced.
  • Marine propulsion engines used on board ships are 4-stroke engines or 2-stroke, low-speed engines, both of which operate on IFO180, IFO380, MDO and MGO heavy fuel oils and distillates. Due to the high combustion temperatures of greater than 1600 ° C., these engines form the so-called thermal NO x , which is produced by means of an SCR catalyst operating according to the principle of selective catalytic reduction, an introduced reducing agent (usually NH 3 or a precursor compound (precursor ) is converted by this and oxygen (0 2).
  • an introduced reducing agent usually NH 3 or a precursor compound (precursor ) is converted by this and oxygen (0 2).
  • the structure of an SCR system varies according to the technical requirements and is adapted to this individually.
  • the basic principle is based on the following structure:
  • the reducing agent is added to the still polluted exhaust gas and mixed homogeneously with it.
  • the reducing agent is ammonia (NH 3 ), ammonia water or urea.
  • NH 3 ammonia
  • ammonia water or urea the reducing agent is ammonia
  • the Abgas free exhaust gas leaves the catalyst as possible without NH 3 slip.
  • This general principle can be extended by additional components depending on requirements. For example, arrangements with an oxidation catalyst, an ammonia barrier catalyst or a hydrolysis catalyst if the reducing agent consist of dry urea. should be formed, conceivable.
  • These can optionally be combined with the SCR catalyst by upstream or downstream.
  • the nitrogen oxides formed in the internal combustion engine are reduced in the presence of the reducing agent to nitrogen (N 2 ) and water (H 2 O).
  • the reducing agent is either added directly to the exhaust gas or a precursor of the reducing agent is added, which releases the reducing agent only in the exhaust aftertreatment system.
  • ammonia NH 3
  • urea a precursor to the exhaust gas stream, which is then thermolytically and hydrolytically converted to NH 3 , H 2 0 and C0 2 .
  • the so-called cell density indicates the number of channels per area (square inches).
  • the designs used in the art here range from 25 to 400 cpsi (cells per square inch) as a typical value for ceramics and up to 1200 cpsi for high-cell, high-capacity versions with metallic supports.
  • the wall thickness is often just 30 ⁇ .
  • the limiting factor here is the tolerable pressure drop.
  • the carrier component is demanded high thermal and mechanical strength, since it is often exposed to strong temperature fluctuations and shocks.
  • a heat-resistant metal grid or a ceramic mat around the honeycomb body therefore ensures the fixation in the housing and the absorption of vibrations.
  • Catalytic converters commonly used in the automotive and power plant industries usually have a honeycomb honeycomb structure. with a high heat and impact resistance as a carrier material.
  • Cordierite a magnesium-aluminum-silicate material (2MgO ⁇ 2AI 2 0 3 ⁇ 5Si0 2 ), is characterized by a high temperature resistance and a high porosity of 20 to 40% by volume, mainly consisting of macropores with average diameters of a few micrometers, off.
  • Honeycomb catalysts such as.
  • the publications DE 102 55 612 A1, EP 1 063 396 A2, EP 1 713 584 A1 and EP 1 920 834 A1 disclose a large number of cells per square centimeter and have wall thicknesses between 0.2 and 1, 5 mm, with wall thicknesses between 0.2 to 0.3 mm are preferred.
  • the disadvantage of these small wall thicknesses is that mechanical loads, such as pressure surges caused by the so-called “soot blowing", can lead to damage Ship engines, emissions in the form of particles, soot, metal ashes, metals and sulfates, which deposit in the honeycomb of the honeycomb catalyst and lead to a decrease in the catalytic activity of the catalyst and an increase in the pressure loss
  • the invention is therefore the object of an exhaust gas purification whose properties meet the requirements of the engine and in particular the large engine industry for use as exhaust gas denitrification in heavy oil-fired diesel engines.
  • an exhaust gas purification device for reducing nitrogen oxides in the exhaust stream of an internal combustion engine.
  • the exhaust gas purification device comprises a catalyst reactor unit with a reactor housing, which has a multiplicity of number of input and output ports, and arranged with a plurality in the reactor housing and subsequent to the inlet openings Rohgaskaskaden and arranged with a plurality in the reactor housing and subsequent to the outlet openings pure cascade.
  • the exhaust gas purification device comprises, introduced into the reactor housing, from the exhaust gas stream through ström bare bed of catalyst elements, wherein the catalyst elements comprise a support of a foam metal and a catalytic coating for selective catalytic reduction (SCR) of nitrogen oxides.
  • This exhaust gas purification device is characterized by a significantly smaller volume of construction than conventional honeycomb catalysts offer. This makes it much easier to subsequently integrate an exhaust gas purification device in the exhaust system of a ship.
  • the support made of foam metal are characterized by their insensitivity to thermal expansion and mechanical stress.
  • the bed is flow-optimized and is flowed around during operation of the exhaust stream of the internal combustion engine usually turbulent constantly and flows through.
  • the foam metal of the catalyst elements preferably comprises iron, iron oxide, chromium, aluminum and / or nickel or alloys thereof or preferably consists thereof. Further preferably, the catalyst elements have the geometric shape of a sphere, a hemisphere, a ring, a tube, a Raschid ring, a half-tube, a plate, a cylinder or a cube.
  • the catalyst elements preferably have a length or a diameter of 0.5 to 30 mm, preferably 1 to 15 mm and particularly preferably 2 to 8 mm.
  • the foam metal of the catalyst elements has a specific surface area of 8,000 to 25,000 m 2 / m 3 , in particular from 1 to 18,000 m 2 / m 3 .
  • the foam metal pores having a pore diameter of 100 to 3200 ⁇ , in particular from 400 to 1 .200 ⁇ on.
  • a ceramic carrier preferably cordierite, instead of the foam metal.
  • the catalytic coating comprises a catalytically active material in the form of at least one oxide of a transition metal with atomic number 21 to 30, 39 to 48, 57 to 80 and 89 to 1 12 and / or at least one alkali and / or alkaline earth metal compound and / or at least a compound of the third main group or subgroup of the periodic table and / or at least one rare earth metal or zinc compound or in the form of mixtures of these.
  • the catalytic coating comprises an NH 3 -storing material, in particular aluminum oxide (Al 2 O 3 ), zirconium oxide (ZrO) or a zeolite of the type X, Y and / or ZSM-5.
  • the aluminum oxide (Al 2 O 3 ), the zirconium oxide (ZrO) or the zeolite forms the basic structure of the coating on which the catalytically active material is present in free distribution.
  • the catalytic coating comprises a catalytically active material for the conversion of hydrocarbons (HC).
  • hydrocarbons may be, for example, C 1 - to C 10 -hydrocarbons, in particular CH 4 to C 10 H 2 2 (alkanes).
  • the catalytically active material is usually a combination of suitable noble metals.
  • the coating of the foam metal support with catalysts, as well as with the NH 3 - storing material is usually carried out by means of a washcoat process, as is also known for conventional honeycomb-shaped metal or ceramic carriers.
  • the NH 3 - electriciannde material preferably has a BET surface area of at least 300 m 2 / g, especially at least 400 m 2 / g and particularly preferably of at least 500 m 2 / g. Furthermore, the material storing NH 3 preferably has a particle size of at most 0.9 ⁇ m, in particular of not more than 0.6 ⁇ m, and particularly preferably of not more than 0.3 ⁇ m. Furthermore, the NH 3- storing material preferably has an average pore size of 0.4 to 1 nm, more preferably 0.7 to 0.8 nm.
  • the crude gas and / or the pure cascade comprise in the flow direction (ie axially) extending elements.
  • the raw gas can also be transported into the regions of the catalyst unit which are opposite the inlet openings and / or or out of which passage opening opposite areas are discharged. This allows an equally distributed flow through the bed.
  • the elements of the raw gas and / or pure-hydrogen cascades extending in the direction of flow have a roof-like shape.
  • the roof-like shape designates a molding, which is closed at the top and open at the bottom.
  • an element extending in the direction of flow has a cross-sectionally normal shape to the flow direction in the form of a second limb. The intersection of the two legs shows in the assembled state of the exhaust gas purification device upwards.
  • the elements of the crude gas and / or pure-gas cascades extending in the direction of flow are formed as two, preferably flat, surfaces arranged at an angle to one another, whose cut line forms the highest point of the raw gas and / or the pure cascade.
  • the two legs of the elements of the crude gas and / or pure-gas cascades extending in the flow direction preferably have a limb length of 5 to 30 cm, in particular of 10 to 20 cm, and / or an angle of 15 ° to 1 10 °, in particular of 20 ° to 90 °, preferably from 45 ° to 75 °, on.
  • These embodiments allow a flow-favorable cross section of the channels formed by the roof-like elements extending in the direction of flow.
  • the crude gas and / or the pure cascade cascades are arranged at a distance of 10 to 50 cm, in particular from 15 to 35 cm, to each other. This distance represents a good compromise of flow resistance when flowing through the bed and the effective catalytic surface.
  • the reactor housing of the catalyst reactor unit has discharge means for discharging spent or contaminated catalyst elements.
  • Austragungsmittel are in particular a rotary valve, a screw conveyor or double pendulum flap.
  • an exhaust system for an internal combustion engine comprising an exhaust gas purification device according to the invention.
  • the exhaust system usually includes at least one inlet and outlet, which direct the raw gas to the exhaust gas purification device and away from the exhaust gas purification device.
  • the exhaust system further comprises a metering device arranged upstream of the exhaust gas purification device for metering a reducing agent into the exhaust gas flow, in particular of ammonia (NH 3 ) or a precursor compound therefrom.
  • the metering device allows insertion, z. For example, an injection of the reducing agent or its precursor compound in the exhaust stream.
  • the exhaust system further comprises a burner arranged upstream of the exhaust gas purification device for increasing the exhaust gas temperature.
  • the burner can furthermore preferably be operated with liquid or gaseous fuels, in particular with a boil-off of a liquid-gas tank.
  • a method for operating an exhaust system according to the invention comprises a first step of providing an exhaust system according to the invention. Furthermore, the method comprises a second step of introducing the exhaust gas flow into the catalyst reactor unit through the inlet openings and at least partially through the raw gas cascades. Moreover, the method comprises a third step of passing the exhaust gas flow through the bed of catalyst elements. Furthermore, the method comprises a fourth step of discharging the exhaust gas stream from the catalyst reactor unit at least partially through the clean gas cascades and through the outlet openings.
  • a subset of the catalyst elements is discharged from the device upon reaching a predetermined pressure loss and / or a predetermined ⁇ -clean gas concentration threshold and replaced by not yet acted catalyst elements.
  • a uniform operation of the catalyst over the operating time can be ensured. Nevertheless, a continuous discharge and replenishment of catalyst elements is possible.
  • the reducing agent required for the catalytic reduction is metered only when a defined temperature is reached. As a result of this embodiment, flooding of the catalyst reactor unit with reducing agent can be prevented, as long as a minimum temperature necessary for the catalytic reaction has not yet been reached.
  • a pyrolysis of the urea metered in upstream of the exhaust gas purification device takes place in a crude gas hood of the exhaust gas purification device, which adjoins the reactor housing on the input side.
  • the exhaust gas flow is guided through the raw gas hood, which distributes the exhaust gas flow to the inlet openings.
  • the exhaust gas purification device will operate in overpressure, which is due to the flow resistance of the catalyst reactor unit and the pressure of the exhaust gas flow from the internal combustion engine.
  • the exhaust gas purification device is preferably operated under reduced pressure, which is generated by means of a fan arranged downstream of the catalyst reactor unit.
  • the control of the dosage of the reducing agent in dependence on an operating point of the internal combustion engine, for which in particular a characteristic value from the engine control unit is used.
  • the characteristic value from the engine control unit represents a quantity leading the exhaust gas flow, whereby the dosage of the reducing agent can be adjusted before the exhaust gas flow arrives at the metering device.
  • FIG. 1 shows an exhaust system according to the invention
  • FIG 2 shows a cross section through an exhaust system.
  • Figure 1 is a schematic view of an exhaust system according to the invention according to a preferred embodiment.
  • An exhaust gas purification device of the exhaust system comprises a catalyst reactor unit 51, with arranged within a reactor housing 52 Rohgaskaskaden 60 and pure cascade 80.
  • the raw and clean cascades 60, 80 may be arranged as shown in parallel and in the flow direction of the exhaust stream. As shown, the raw gas cascades 60 may already end before the side of the reactor housing 52 opposite the inlet openings 53, or may adjoin them. Likewise, the pure cascade cascades 80 may end, as shown, before the side of the reactor housing 52 opposite the outlet openings 54, or else adjoin them.
  • the reactor housing 52 is filled with a bed 90 of catalyst elements.
  • the catalyst elements comprise a carrier
  • Foam metal, as well as a catalytic coating for the selective catalytic reduction (SCR) of nitrogen oxides In an upper region of the reactor housing 52, a supply silo 70 is arranged, while in a lower region of the reactor housing 52 a discharge means 120 is arranged.
  • the raw gas cascades 60 are fluidly connected to a raw gas hood 40 via inlet openings 53, and clean gas cascades 80 are fluidly connected to a clean hood 100 via outlet openings 54.
  • the raw gas hood 40 serves as a distributor for dividing the exhaust gas flow onto the inlet openings 53, while the clean gas hood 100 serves as a collector for collecting the exhaust gas flow from the outlet openings 54.
  • an exhaust gas feed line 50 is arranged, which serves to supply the exhaust gas flow from an internal combustion engine 10 into the crude gas hood 40.
  • a first NO x probe 20, a metering device 30 and a first pressure sensor 150 a are arranged.
  • An exhaust gas outlet 1 10 connects downstream of the clean cover 100 at.
  • a second pressure sensor 150b, a temperature sensor 130 and a second NO x probe 140 are arranged.
  • Figure 2 shows a view of a sectional plane AA through the catalyst reactor unit 51 of the exhaust system.
  • raw gas cascades 60 and clean cascades 80 are alternately arranged in the vertical direction. The viewing direction is in the direction of flow through the raw and clean cascades 60, 80 and through, subsequent to the clean cascade 80 output ports 54.
  • the raw and clean cascades 60, 80 include roof-like, extending in the flow direction elements, the raw and clean cascades 60th , 80 can limit to the top and in cross-section can have a Wegsch- kelige shape.
  • the roof-like, in the flow direction extended When the reactor housing 51 is filled with the bed 90, elements of the raw and clean-water cascades 60, 80 form essentially flow-free channels of the raw and clean-water cascades 60, 80 below the roof-like elements extending in the flow direction.
  • the partial exhaust gas streams can advance in the direction of flow into the catalyst reactor unit 51 in order subsequently to flow through the bed 90 to the clean cascade 80.
  • a uniform loading of the bed 90 is ensured with the exhaust gas stream 90 and also reduces the flow resistance opposite to the exhaust gas flow.
  • the internal combustion engine 10 which has a plurality of cylinders, operates on the 2-stroke or 4-stroke principle and burns fuel of different quality (residual oils, marine diesel MDO or marine gas oil MGO).
  • Potentially used for internal combustion engines have compared with internal combustion engines of road vehicles usually relatively large displacement of greater than 5 liters per cylinder, preferably greater than 10 liters per cylinder, more preferably, however, greater than 20 liters per cylinder.
  • the exhaust gas leaves the cylinders and enters an exhaust manifold.
  • the exhaust manifold is connected to the exhaust gas supply line 50.
  • the exhaust gas flow passes or flows in sequence through the exhaust gas feed line 50 and the raw gas hood 40, in which the exhaust gas flow in the form of multiple partial exhaust gas streams is distributed to the inlet openings 53 of the Rohgaskaskaden 60.
  • the partial exhaust gas streams flow at least partially through the raw gas cascades 60 and then from the raw gas cascades 60 through the bed 90 of catalyst elements to the clean cascade 80.
  • the partial exhaust gas streams of the pure cascade 80 are then combined in the clean gas hood 100 and pass downstream into the exhaust gas discharge line 1
  • the purified waste gas stream can be supplied to further use by heat extraction or be discharged through a chimney to the atmosphere.
  • the reducing agent required for the selective catalytic reduction of nitrogen oxides is fed to the exhaust gas stream as ammonia water or as an aqueous urea solution by means of the metering device 30.
  • the first NO x probe 20 arranged upstream of the metering device 30 determines the NO x concentration of the exhaust gas. From the ⁇ concentration tion, the required amount of reducing agent is calculated, which is metered by means of the metering device 30 in the exhaust gas stream. Alternatively, it is also possible to determine the required amount of reducing agent based on a characteristic value from the engine control unit.
  • the temperature sensor 130 which is installed at the exhaust gas discharge line 10, determines the temperature of the exhaust gas. Upon reaching a desired minimum temperature is started with the dosage of the reducing agent.
  • the minimum temperature may be between 140 ° C and 270 ° C, depending on the exhaust gas composition.
  • the operating temperature of the exhaust gas purification device may be between 140 ° C and 500 ° C.
  • the reducing agent in the form of an aqueous urea solution is thermolyzed in the exhaust gas stream and hydrolyzed, whereby the urea is degraded by means of a chemical reaction to ammonia (NH 3 ):
  • This pyrolysis of the urea takes place partially or even mainly in the raw gas hood 40.
  • the exhaust gas mixed with the reducing agent is further mixed in the raw gas hood 40 and uniformly supplied through the raw gas cascades 60 to the catalyst reactor unit 51 for selective catalytic reduction.
  • the exhaust gas leaves the crude gas cascades 60 and flows in turbulent form through the catalyst elements consisting of bed 90, in which it comes to the desired selective catalytic reaction, for example, according to the following reaction equations:
  • Denitrification by an SCR causes deliberate and unwanted reactions, as there is no chemical reaction that is 100% selective. That is, there are also side reactions, some of which are desirable.
  • the NO x can be implemented in various ways in the catalyst. These different reactions compete at the. Whichever prevails depends on different factors. Dwell time of the gas in the reactor, substance concentrations, the nature of the catalyst and above all the temperature are the determining factors. A theoretical assessment of which reaction predominates for a given catalyst at a given temperature is difficult. It is not always clear which mechanism (Eley-Rideal, Longmuir-Henschelwood) exists. In practice, equations for the reaction kinetics are usually determined empirically and their evaluation provides information about a possible reaction mechanism.
  • the catalyst elements of the bed 90 usually contain at least one oxide of a transition metal with the atomic number 21 to 30, 39 to 48, 57 to 80 and 89 to 1 12, an alkali or alkaline earth metal compound and / or a compound of the third main or subgroup of the Periodic Table and / or a rare earth metal or zinc compound or mixtures thereof.
  • the catalyst elements of the bed 90 have a length or diameter of z. B. 1 to 30 mm, preferably 2 to 8 mm, in the geometric shape of a tube, a Raschid ring, a ball, a cube of a cylinder or a plate, which consists of a foam metal, for. B. of iron oxide or nickel and a large porosity in the form of pores with a diameter of z. B. 100 to 2000 ⁇ , preferably 400 to 1200 ⁇ , and a large specific surface area of z. B. 8000 to 25000 m 2 / m 3 , preferably 1 1000 to 18000 m 2 / m 3 , have.
  • the second NO x probe 140 which is attached to the exhaust gas discharge line 1 10, determines the NO x concentration of the purified exhaust gas flow and provides the measured value as a further controlled variable of the metering device 30 in order to prevent any NH 3 slip or NO x - Minimize slippage.
  • the purified exhaust gas passes through the exhaust pipe 1 10 to any further downstream exhaust treatment facilities, a device for heat extraction or through a fireplace in the atmosphere.
  • the contaminated catalyst elements may be removed from the catalyst reactor by means of a discharge means 120, e.g. B. a rotary valve and replaced by nachurgingende catalyst elements from the storage silo 70.
  • the decrease in activity is determined by the second NO x probe 140.
  • the total pressure loss of the exhaust gas purification device is determined by means of the pressure sensors 150a and 150b. If the total pressure loss exceeds a permissible value, a portion of the bed 90 consisting of catalyst elements is discharged by putting the discharge means 120 into operation and replaced by slipping catalyst elements out of the storage silo 70.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Combustion & Propulsion (AREA)
  • Health & Medical Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Toxicology (AREA)
  • General Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Environmental & Geological Engineering (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

L'invention concerne un dispositif de purification des gaz d'échappement pour la réduction des oxydes d'azote dans un flux de gaz d'échappement d'un moteur à combustion interne (10). Le dispositif de purification des gaz d'échappement comprend : (a) un ensemble réacteur catalytique (51) doté d'une enveloppe de réacteur (52), qui comporte une pluralité d'ouvertures d'entrée et de sortie (53, 54), et doté d'une pluralité de cascades de gaz bruts (60) disposées dans l'enveloppe de réacteur (52) et raccordées aux ouvertures d'entrée (53) et doté d'une pluralité de cascades de gaz épurés (80) disposées dans l'enveloppe de réacteur (52) et raccordées aux ouvertures de sortie (54); et (b) un garnissage (90) d'éléments catalyseurs, placé dans l'enveloppe de réacteur (52), pouvant être traversé par le flux de gaz d'échappement, les éléments catalyseurs comportant un support en métal expansé ainsi qu'un revêtement catalytique pour la réduction catalytique sélective (SCR) des oxydes d'azote. La présente invention concerne en outre un système d'échappement comprenant le dispositif de purification des gaz d'échappement et un procédé permettant de faire fonctionner le système d'échappement.
PCT/EP2012/060215 2011-05-31 2012-05-31 Dispositif de purification des gaz d'échappement pour la réduction des oxydes d'azote dans un flux de gaz d'échappement de moteurs à combustion interne Ceased WO2012164000A2 (fr)

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DE102011076814 2011-05-31
DE102011076814.9 2011-05-31
DE102012203574A DE102012203574A1 (de) 2011-05-31 2012-03-07 Abgasreinigungsvorrichtung zur Verminderung von Stickoxiden im Abgasstrom von Brennkraftmaschinen
DE102012203574.5 2012-03-07

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US9387438B2 (en) 2014-02-14 2016-07-12 Tenneco Automotive Operating Company Inc. Modular system for reduction of sulphur oxides in exhaust

Citations (5)

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Publication number Priority date Publication date Assignee Title
DE3428232A1 (de) 1984-07-31 1986-02-06 Süd-Chemie AG, 8000 München Katalysator zur entfernung von stickoxiden aus abgasen
EP1063396A2 (fr) 1999-06-22 2000-12-27 Ngk Insulators, Ltd. Structure céramique en nid d'abeilles, support de catalyseur en nid d'abeilles et catalyseur céramique en nid d'abeilles utilisant ceux-ci
DE10255612A1 (de) 2001-11-29 2003-06-12 Denso Corp Keramischer Katalysatorkörper
EP1713584A1 (fr) 2004-02-04 2006-10-25 Ibiden Co., Ltd. Structure en nid d'abeilles, ensemble de structure en nid d'abeilles, et catalyseur en nid d'abeilles
EP1920834A1 (fr) 2005-08-31 2008-05-14 Ngk Insulators, Ltd. Catalyseur en nid d'abeille et son procédé de production

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030116023A1 (en) * 2001-12-24 2003-06-26 Bor-Jye Liang Method of anti-pollution for exhaust and apparatus thereof
DE10221668B4 (de) * 2002-05-16 2005-04-28 Daimler Chrysler Ag Kugelkatalysator für Verbrennungskraftmaschinen und Verfahren zur Katalyse von Abgasen bzw. Schadstoffgemischen
WO2011060792A2 (fr) * 2009-11-20 2011-05-26 Dansk Teknologi Produktionsaktieselskab Système de réduction catalytique sélective

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3428232A1 (de) 1984-07-31 1986-02-06 Süd-Chemie AG, 8000 München Katalysator zur entfernung von stickoxiden aus abgasen
EP1063396A2 (fr) 1999-06-22 2000-12-27 Ngk Insulators, Ltd. Structure céramique en nid d'abeilles, support de catalyseur en nid d'abeilles et catalyseur céramique en nid d'abeilles utilisant ceux-ci
DE10255612A1 (de) 2001-11-29 2003-06-12 Denso Corp Keramischer Katalysatorkörper
EP1713584A1 (fr) 2004-02-04 2006-10-25 Ibiden Co., Ltd. Structure en nid d'abeilles, ensemble de structure en nid d'abeilles, et catalyseur en nid d'abeilles
EP1920834A1 (fr) 2005-08-31 2008-05-14 Ngk Insulators, Ltd. Catalyseur en nid d'abeille et son procédé de production

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