WO2008020207A1 - Traitement de gaz d'échappement - Google Patents

Traitement de gaz d'échappement Download PDF

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Publication number
WO2008020207A1
WO2008020207A1 PCT/GB2007/003115 GB2007003115W WO2008020207A1 WO 2008020207 A1 WO2008020207 A1 WO 2008020207A1 GB 2007003115 W GB2007003115 W GB 2007003115W WO 2008020207 A1 WO2008020207 A1 WO 2008020207A1
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WO
WIPO (PCT)
Prior art keywords
reaction vessel
valve
engine according
hydrolysis product
exhaust
Prior art date
Application number
PCT/GB2007/003115
Other languages
English (en)
Inventor
David Mills
Alan Bhimani
Keith James Heyes
Original Assignee
Imi Vision Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Imi Vision Limited filed Critical Imi Vision Limited
Publication of WO2008020207A1 publication Critical patent/WO2008020207A1/fr

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Classifications

    • 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
    • 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
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/90—Injecting reactants
    • 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
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
    • F01N13/08—Other arrangements or adaptations of exhaust conduits
    • F01N13/10—Other arrangements or adaptations of exhaust conduits of exhaust manifolds
    • 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 ; Methods of operation or control of catalytic converters
    • F01N3/2066—Selective catalytic reduction [SCR]
    • 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
    • F01N5/00—Exhaust or silencing apparatus combined or associated with devices profiting by exhaust energy
    • F01N5/02—Exhaust or silencing apparatus combined or associated with devices profiting by exhaust energy the devices using heat
    • 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
    • B01D2251/2067—Urea
    • 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
    • F01N2240/25—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 an ammonia generator
    • 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
    • F01N2240/40—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 hydrolysis 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
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/02—Adding substances to exhaust gases the substance being ammonia or urea
    • 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
    • F01N2610/06—Adding substances to exhaust gases the substance being in the gaseous form
    • 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
    • F01N2610/10—Adding substances to exhaust gases the substance being heated, e.g. by heating tank or supply line of the added substance
    • 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
    • F01N2610/14—Arrangements for the supply of substances, e.g. conduits
    • 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
    • F01N2610/14—Arrangements for the supply of substances, e.g. conduits
    • F01N2610/1406—Storage means for substances, e.g. tanks or reservoirs
    • 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
    • F01N2610/14—Arrangements for the supply of substances, e.g. conduits
    • F01N2610/1453—Sprayers or atomisers; Arrangement thereof in the exhaust apparatus
    • 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 present invention relates to an arrangement for reducing emissions of Nitrogen oxides (NOx ) in exhaust gasses of an internal combustion (IC) engine, especially but not exclusively a diesel engine of, for example, a vehicle.
  • IC internal combustion
  • the known systems principally fall into one of two categories, those which introduce gaseous ammonia into the exhaust conduit and those which introduce into the exhaust conduit a liquid reagent which decomposes into ammonia gas in the conduit.
  • the liquid reagent is, at ambient temperatures, a stable medium, but it decomposes at elevated temperatures to form at least ammonia gas. It is preferably an aqueous solution of urea or related substance such as biuret or ammonium carbamate, collectively referred to, and defined, herein as "urea". While this solution to the problem provides a satisfactory result, there are a number of problems associated with it. Firstly, the liquid is injected through a nozzle as a fine spray of droplets into the fast flowing exhaust gas in which it preferably fully decomposes into at least ammonia gas prior to contacting the SCR catalyst.
  • an IC engine having a device for generating gaseous hydrolysis product comprising ammonia, formed by the hydrolysis of an aqueous solution of urea (as hereinbefore defined) at elevated temperature and pressure, and feeding it into the exhaust gas of the engine as it flows through the exhaust system thereof, the device comprising: a) at least one reaction vessel located in, or immediately adjacent to, the exhaust manifold of the engine for containing an aqueous solution of urea and arranged such that, in use, the urea solution within the reaction vessel becomes heated by means of heat exchange with the exhaust gas; b) a urea solution inlet to the reaction vessel and a hydrolysis product outlet from the reaction vessel; and c) a conduit arranged to convey the hydrolysis product from the reaction vessel to a point of introduction into the exhaust system downstream and remote from said manifold; and d) valve means adapted to permit the contents of the reaction vessel, in use, to attain an elevated pressure as it becomes heated, to discharge hydrolysis product from the reaction
  • reaction vessel By placing the reaction vessel in, or immediately adjacent to, the exhaust manifold of the engine it is located in the area of hottest exhaust gas, thereby maximising heat exchange to the reaction vessel.
  • maximising the heat exchange to the reaction vessel the time taken to hydrolyse the urea therein is significantly reduced enabling a more responsive system as the production rate of urea can quickly be modified in response to changes in engine conditions and the related changes in NOx concentration in the exhaust gas.
  • reaction time to hydrolyse urea is measured in seconds rather than minutes, it may be possible, depending on the application, to feed the hydrolysis product hydrolysis product directly into the exhaust conduit from the reaction vessel.
  • the hydrolysis product may be desirable to discharge into a reservoir whence it is fed, in a controlled manner, into the exhaust gas.
  • the temperature at a position in or adjacent the exhaust manifold most closely matches the actual engine conditions thereby removing time lag from the system.
  • the engine comprises a cylinder head having cylinder outlet ports therein and the reaction vessel is located within at least one of said outlet ports in the exhaust gas flow such that it is heated by heat exchange with the exhaust gas as it exits the cylinders via the outlet ports. This is the point at which the exhaust gas is at its hottest and as such it is a preferred location for the reaction vessel.
  • the engine comprises an exhaust manifold for collecting the exhaust gasses from the cylinders of the engine and the reaction vessel is embodied in the exhaust manifold, preferably internally of it. While the exhaust gas will cool slightly in the manifold there are advantages associated with such an arrangement. In particular, it allows the exhaust manifold with the reaction vessel therein to be assembled as a sub-component and then attached to the engine as a complete element. This enables the engine build time to remain unchanged. In addition it facilitates maintenance because if a system is not functioning correctly, the manifold and reaction vessel can simply be removed as a complete item and replaced, thereby minimising down time of the engine.
  • the reaction vessel when the reaction vessel is located within the exhaust gas flow, i.e. it is exposed directly to the exhaust gas, it comprises a metal pressure vessel having a plurality of heat exchange fins thereon to maximise, in use, heat transfer from the exhaust gas to the urea solution within the reaction vessel.
  • the reaction vessel is formed integrally with the body of the exhaust manifold, more preferably the exhaust manifold is a cast component and the reaction vessel comprises a hollow cavity cast into the exhaust manifold.
  • the reaction vessel comprises a metal lining inserted into the hollow cavity, said metal lining in thermal contact with the exhaust manifold.
  • the lining body is of stainless steel. This both protects the cast metal from the hydrolysis products and enables the reaction vessel to withstand higher pressures that the casting alone.
  • the cavity is tubular and the lining comprises a piece of stainless steel tube inserted into the cavity.
  • the reaction vessel contains a hydrolysis catalyst to increase the speed of the hydrolysis reaction.
  • the catalyst is a zeolite or another of the hydrolysis catalysts known in the art.
  • the valve means consists of a single valve.
  • the single valve is an fully on/off valve and the reaction vessel is operated in a batch production mode whereby aqueous urea is pumped, from a pump into the reaction chamber, is heated therein for a period of time, during which the pressure becomes elevated, sufficient for the urea to hydrolyse and the valve is selectively opened to allow the hydrolysis product to be expelled therefrom by means of the pressure which has built up within the reaction vessel.
  • valve may be a pressure relief valve and the reaction vessel is partially filled with urea such that the pressure relief valve is above the level of the liquid and as the urea hydrolyses the hydrolysis products are released in gaseous form through the pressure relief valve in a continual process.
  • a conduit leads from the valve to the point of introduction of hydrolysis product into the exhaust gas.
  • Preferably at least a section of the conduit is heated by heat exchange with the hot exhaust gasses, and any liquid phase hydrolysis product exiting the reaction vessel is converted to gaseous phase hydrolysis product in said conduit.
  • valve means may comprise two valves, a first one adapted to permit the contents of the reaction vessel to attain an elevated pressure and to discharge hydrolysis product from the reaction vessel, and a second one for selectively controlling the feed of hydrolysis product into the exhaust gas, there being a conduit between them preferably comprising a reservoir which acts as a buffer between the output rate of hydrolysis produce from the reaction vessel and the input rate of hydrolysis product into the exhaust such that input of hydrolysis product into the exhaust is controlled independently of output from the reactor vessel, hi a preferred arrangement the first valve is an on/off valve and the reaction vessel is operated in a batch process as described above, hi this case the periodic discharge from the reaction vessel may not exactly meet the requirements of addition of hydrolysis product to the exhaust gas and the conduit acts as a buffer to temporarily store the hydrolysis product before it is introduced into the exhaust gas via the second valve that selectively controls the feed of hydrolysis product.
  • the valve to permit the contents of the reaction vessel, in use, to attain an elevated pressure as it becomes heated, and to discharge hydrolysis product from the reaction vessel may
  • the conduit is at least partially heated by heat exchange with the hot exhaust gasses such that any liquid phase hydrolysis product discharged from the reaction vessel is converted to gaseous phase hydrolysis product within the conduit prior to passing through the second valve.
  • valve in the outlet of the reaction vessel is an on/off valve
  • a further valve in parallel with the valve in the outlet from the reaction vessel.
  • the further valve is a pressure relief valve and both valves control the discharge of hydrolysis product form the reaction vessel.
  • Li use a volume of urea is pumped into the chamber to partially fill it and the on/off valve is closed. As the urea becomes heated the gas pressure above the liquid level increases. Once the pressure reaches the set value of the pressure relief valve excess gas will vent out of the further, e.g. pressure relief, valve ensuring that a maximum required pressure within the reaction vessel is not exceeded.
  • the on/off valve is opened and the contents of the reaction vessel exits via the on/off valve.
  • the on/off valve is placed below the liquid level within the reaction vessel such that its contents are expelled therefrom by the head pressure above it.
  • reaction vessels there is a plurality of reaction vessels and the frequency at which they are discharged, and/or the volume of urea supplied to them, and therefore the volume of hydrolysis product discharged from them, is increased in relation to the amount of NOx in the exhaust gas.
  • the IC engine has a turbocharger downstream of the exhaust manifold and the point of introduction of the hydrolysis product into the exhaust gas is downstream of the turbocharger.
  • a turbocharger downstream of the exhaust manifold and the point of introduction of the hydrolysis product into the exhaust gas is downstream of the turbocharger.
  • the turbocharger is a very fast moving turbine and it is detrimental to its performance and life if particulate material is passed through it, especially in its hot operating state.
  • the exhaust system of the IC engine further comprises an oxidation catalyst to convert a proportion of the NO contained within the exhaust gas to NO 2 , and the point of introduction of hydrolysis product into the exhaust gas is downstream of the oxidation catalyst. If a substantially equal balance of NO and NO 2 can be achieved in the exhaust gas then the urea needed is minimised and performance requirements of the reactor vessel are reduced.
  • the present invention also provides a exhaust manifold for an IC engine, said manifold including a urea hydrolysis reaction vessel for containing, in use, an aqueous urea solution, the reaction vessel having a urea solution inlet and a hydrolysis product outlet.
  • Figure 1 shows a perspective view of a typical IC engine
  • Figure 2 shows a perspective view of the engine of Figure 1 with the exhaust manifold omitted;
  • Figure 3 shows a perspective view of an engine showing a number of reaction vessels arranged in the port outlets
  • Figure 4 shows an exhaust manifold according to the present invention
  • Figure 5 is an enlarged view of a portion of Figure 4;
  • Figure 6 shows a reaction vessel suitable for placement in the outlet ports;
  • Figure 7 is a schematic diagram of system using a reaction vessel shown in Figure 6;
  • Figure 8 is a perspective view of an exhaust manifold according to the present invention.
  • Figures 9 and 10 are section views of an exhaust manifold according to the present invention.
  • Figure 11 is a perspective view of an alternative exhaust manifold according to the present invention.
  • Figures 12 and 13 are section views of an exhaust manifold shown in Figure 11;
  • a turbocharged internal combustion engine 1 such as may be found on a truck or small commercial vehicle.
  • Such engines are well known in the art and comprise a number of cylinders in which combustion occurs, the combustion drives pistons within the cylinders which rotate a camshaft from which power is transmitted to its final use - in the case of a vehicle the power is transmitted to the wheels.
  • the main part of the engine typically comprises a number of parts which are bolted together, one of these, the cylinder head 2, encloses one end of the cylinders.
  • the cylinder head 2 has a plurality of cylinder outlet ports 3a, b, c, d, e & f, through which the exhaust gasses exiting the cylinders, post combustion, pass.
  • the hot exhaust gasses then pass into and through an exhaust manifold where the exhaust gas flows from the individual cylinders join together.
  • the exhaust gasses exit a manifold 4 and pass into a turbocharger 5.
  • FIG. 3 the engine 1 of Figures 1 and 2 is shown with the manifold 4 omitted for clarity.
  • a plurality of reaction vessels 6a, b, c, d, e, f are shown, each with an associated feed pipe 7a, b, c, d, e, f for feeding aqueous urea solution from a control block 8 into the reaction vessels.
  • the control block 8 is shown located on the engine but it may be located anywhere conveniently in the vicinity of the engine.
  • the control block 8 is operated to feed a small amount of aqueous urea into the reaction vessels 6 via their associated feed pipes 7.
  • the reaction vessels 6 and therefore the urea within them are heated by the flow of hot exhaust gasses past the reaction vessels 6.
  • valve 10 is an on/off solenoid valve and the conduits 9 lead to a buffer vessel 11 that temporarily stores the hydrolysis product prior to it being introduced into the exhaust gas downstream of the turbocharger.
  • the hydrolysis product may be released directly into the exhaust either periodically via an on/off solenoid valve, or continuously via a pressure relief valve, downstream of the turbocharger.
  • the hydrolysis gas and the exhaust gas then flow together through an SCR catalyst wherein the ammonia in the hydrolysis gas reacts with the NOx in the exhaust gas substantially converting it to nitrogen and water.
  • an exhaust manifold 12 is shown that is adapted to hold a plurality of reaction vessels 13 such that they project past the flanges 14, which attach the exhaust manifold 12 to the engine, and into the outlet ports of the engine.
  • the reaction vessel 13 has a plurality of fins 17 attached to its outer surface to enhance heat transfer from the hot exhaust gasses passing over the outer surface of the reaction vessel 13.
  • a pump 18 ( Figure 7) pumps aqueous urea from a reservoir 19 into the reaction vessel 13 via valve 20.
  • the pump 18 and valve 20 are operated to introduce a small amount of aqueous urea, about 10ml, into the reaction vessel 13.
  • the urea becomes heated and starts to decompose. As it decomposes some of the decomposition products become gaseous causing the pressure and therefore, with the continuing input of heat, the temperature to rise.
  • the decomposition products are carbon dioxide, ammonia and water.
  • the second valve 22 a discharge valve, is located in parallel with the pressure relief valve 21 and once the aqueous urea has been held in the reactor sufficiently long enough for it to fully hydrolyse this valve 22 is opened and the pressure within the reaction vessel 13 will expel its contents therethrough.
  • a conduit 24 connects the valves and the reservoir 23. Downstream of the reservoir 23 is a dosing valve 25 ( Figure 7) which operates to dose a volume of the hydrolysis product into the exhaust gas of an IC engine via a nozzle 26.
  • an exhaust manifold 27 for collecting the exhaust flows from exhaust outlet ports of an engine via inlets 28 and combining the flows and ducting them out of the manifold outlet 29 towards a turbocharger.
  • the manifold 27 is manufactured of a cast metal has two reaction vessels 30 cast into it. Each reaction vessel has an inlet 31 at its lower end and an outlet 32 at its upper end.
  • the reaction vessels operate as described in relation to Figures 4 to 7. In both embodiments shown the reaction vessels are operated out of phase with one another so as to provide a substantially continuous flow of hydrolysis product to the exhaust.
  • an exhaust manifold 33 for collecting the exhaust flows from exhaust outlet ports of an engine via inlets 34 and combining the flows and ducting them out of the manifold outlet 35 towards a turbocharger.
  • the manifold 33 is manufactured of a cast metal and has two reaction vessels 36 cast into it. Each reaction vessel is lined with a stainless steel liner 36a to extend its life. Each reaction vessel has an inlet 37 at its lower end and an outlet 38 at its upper end. The reaction vessels operate as described in relation to Figures 4 to 7.
  • valve unit 39 which contains the pressure relief valve and the discharge valve and, downstream of the valve unit 39, the conduit 40 through which the hydrolysis product flows towards its point of use passes back into the manifold 33.
  • This is a low pressure conduit and due to the heat of the manifold 33, liquid hydrolysis product discharged from the reaction vessel 36 will evaporate in the hot part 41 of the conduit within the manifold thereby ensuring that the hydrolysis product is fully gaseous before it passes into the exhaust gas.
  • the conduit 40 continues towards its point of introduction to the exhaust.
  • the hydrolysis product Prior to entering the exhaust the hydrolysis product may be temporarily stored in a reservoir and its introduction to the exhaust is controlled by a further control valve.
  • conduit 40 may lead directly into the exhaust gas at a point downstream of the turbo.
  • the valve unit 39 may be operated to control the release of the hydrolysis product into the exhaust or a second valve (not shown) may be placed downstream to control the introduction of the hydrolysis product into the exhaust.

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

Abstract

L'invention concerne un moteur à combustion interne doté d'un dispositif générant de l'ammoniac par hydrolyse d'une solution aqueuse d'urée et introduire dans les gaz d'échappement du moteur. Le dispositif comporte un récipient de réaction (13) disposé pour recevoir de l'urée aqueuse d'un réservoir (19) et pour chauffer l'urée aqueuse par échange de chaleur avec les gaz d'échappement. Le récipient de réaction (13) est muni d'un clapet de décharge (21) fixé permettant de maintenir une pression maximale dans le récipient de réaction (13) et d'un clapet de refoulement (22) disposé pour libérer un produit d'hydrolyse du récipient de réaction (13) lorsque l'urée aqueuse est complètement hydrolysée. Les deux clapets (21, 22) communiquent avec un réservoir (23) pour stocker le produit d'hydrolyse. Une soupape de dosage (25) est actionnable pour doser un volume de produit d'hydrolyse dans les gaz d'échappement par l'intermédiaire d'une buse (26).
PCT/GB2007/003115 2006-08-15 2007-08-15 Traitement de gaz d'échappement WO2008020207A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0616149.1 2006-08-15
GBGB0616149.1A GB0616149D0 (en) 2006-08-15 2006-08-15 Exhaust gas treatment

Publications (1)

Publication Number Publication Date
WO2008020207A1 true WO2008020207A1 (fr) 2008-02-21

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Application Number Title Priority Date Filing Date
PCT/GB2007/003115 WO2008020207A1 (fr) 2006-08-15 2007-08-15 Traitement de gaz d'échappement

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GB (1) GB0616149D0 (fr)
WO (1) WO2008020207A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012107637A1 (fr) 2011-02-10 2012-08-16 Wärtsilä Finland Oy Collecteur de gaz d'échappement, moteur à combustion interne et procédé permettant une réduction catalytique sélective
EP2907984A1 (fr) * 2014-02-14 2015-08-19 DEUTZ Aktiengesellschaft Moteur à combustion interne
FR3027056A1 (fr) * 2014-10-10 2016-04-15 Peugeot Citroen Automobiles Sa Dispositif de reduction catalytique selective
WO2018055175A1 (fr) * 2016-09-26 2018-03-29 Plastic Omnium Advanced Innovation And Research Système de véhicule et procédé de génération d'ammoniac en lots
EP3330222A1 (fr) * 2016-12-01 2018-06-06 Loughborough University Procédé de réduction d'oxydes d'azote
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WO2012107637A1 (fr) 2011-02-10 2012-08-16 Wärtsilä Finland Oy Collecteur de gaz d'échappement, moteur à combustion interne et procédé permettant une réduction catalytique sélective
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EP3330222A1 (fr) * 2016-12-01 2018-06-06 Loughborough University Procédé de réduction d'oxydes d'azote
CN108331645A (zh) * 2017-01-18 2018-07-27 温特图尔汽柴油公司 推进系统、用于还原NOx的方法、船舶以及控制系统

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