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WO2008104070A1 - Système de réduction des émissions à l'aide d'un lavage humide - Google Patents

Système de réduction des émissions à l'aide d'un lavage humide Download PDF

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Publication number
WO2008104070A1
WO2008104070A1 PCT/CA2008/000377 CA2008000377W WO2008104070A1 WO 2008104070 A1 WO2008104070 A1 WO 2008104070A1 CA 2008000377 W CA2008000377 W CA 2008000377W WO 2008104070 A1 WO2008104070 A1 WO 2008104070A1
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WIPO (PCT)
Prior art keywords
exhaust
engine
stream
syngas
catalytic oxidation
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Ceased
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PCT/CA2008/000377
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English (en)
Inventor
Erik Paul Johannes
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Nxtgen Emission Controls Inc
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Nxtgen Emission Controls Inc
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Publication of WO2008104070A1 publication Critical patent/WO2008104070A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63H—MARINE PROPULSION OR STEERING
    • B63H21/00—Use of propulsion power plant or units on vessels
    • B63H21/12—Use of propulsion power plant or units on vessels the vessels being motor-driven
    • B63H21/14—Use of propulsion power plant or units on vessels the vessels being motor-driven relating to internal-combustion engines
    • 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
    • B01D53/8637—Simultaneously removing sulfur oxides and nitrogen oxides
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63H—MARINE PROPULSION OR STEERING
    • B63H21/00—Use of propulsion power plant or units on vessels
    • B63H21/32—Arrangements of propulsion power-unit exhaust uptakes; Funnels peculiar to vessels
    • 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
    • F01N13/009—Exhaust or silencing apparatus characterised by constructional features having two or more separate purifying devices arranged in series
    • 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
    • F01N13/011—Exhaust or silencing apparatus characterised by constructional features having two or more purifying devices arranged in parallel
    • 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
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/04—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust using liquids
    • 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
    • F01N3/105—General auxiliary catalysts, e.g. upstream or downstream of the main catalyst
    • F01N3/106—Auxiliary oxidation catalysts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/30—Sulfur compounds
    • B01D2257/302—Sulfur oxides
    • 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
    • B01D2258/00—Sources of waste gases
    • B01D2258/01—Engine exhaust gases
    • B01D2258/012—Diesel engines and lean burn gasoline engines
    • 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
    • B01D53/77—Liquid phase processes
    • 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
    • F01N2570/00—Exhaust treating apparatus eliminating, absorbing or adsorbing specific elements or compounds
    • F01N2570/04—Sulfur or sulfur oxides
    • 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
    • F01N2570/00—Exhaust treating apparatus eliminating, absorbing or adsorbing specific elements or compounds
    • F01N2570/14—Nitrogen oxides
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B37/00—Engines characterised by provision of pumps driven at least for part of the time by exhaust
    • 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
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • 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
    • 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
    • Y02T70/00—Maritime or waterways transport
    • Y02T70/50—Measures to reduce greenhouse gas emissions related to the propulsion system
    • 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
    • Y02T70/00—Maritime or waterways transport
    • Y02T70/50—Measures to reduce greenhouse gas emissions related to the propulsion system
    • Y02T70/5218—Less carbon-intensive fuels, e.g. natural gas, biofuels
    • 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
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02T90/40—Application of hydrogen technology to transportation, e.g. using fuel cells

Definitions

  • the present invention relates to the after-treatment of combustion engine exhaust streams to reduce the amount of deleterious constituents in the exhaust streams. More particularly, the present invention relates to a combustion engine exhaust after- treatment system and method that incorporates catalytic oxidation, o wet scrubbing, and the production of syngas for catalyst regeneration.
  • NO x In lean burn combustion engines, NO x , SO x and particulate matter are typically formed during the combustion 5 process.
  • NO x comprises 70% - 95% nitric oxide (NO) and a portion of nitrogen dioxide (NO 2 ).
  • NO 2 nitrogen dioxide
  • the sulfur content of the fuel results in the formation of SO x .
  • SCR selective catalytic reduction
  • Lean NO x traps operate by adsorbing nitrogen oxides (NO x ) from the engine exhaust during lean (excess oxygen) exhaust conditions and desorbing and catalytically converting NO x into nitrogen (N 2 ) during rich (excess fuel) exhaust conditions.
  • the rich exhaust conditions required for regeneration of the LNT can be created by introducing a reducing agent into the engine exhaust stream.
  • Lean NO x traps typically contain an oxidation catalyst, for example platinum (Pt); an adsorbent, for example barium oxide (BaO); and a reduction catalyst, for example rhodium (Rh).
  • Pt platinum
  • BaO barium oxide
  • Rh rhodium
  • the exhaust stream of a lean burn combustion engine can contain concentrations of sulfur species, originating from the engine fuel and oil.
  • the sulfur species are preferentially adsorbed over NO x , occupying available adsorbent sites and "poisoning" the catalyst.
  • Methods to effectively desulfate the LNT are being improved, but sulfur o poisoning is still generally an issue when the fuel contains high levels of sulfur.
  • Seawater scrubbing is a prior approach to reducing atmospheric emissions of sulfur oxides (SO x ) from thermal power stations, metal smelters, oil refineries and marine propulsion5 systems.
  • SO x sulfur oxides
  • seawater is typically pumped and introduced into the combustion exhaust stream.
  • the acidic SO x gas is absorbed and neutralized by the natural alkalinity of the seawater to produce sulfates. Sulfates occur naturally in seawater and the additional levels from the scrubbing process have no o environmental impact.
  • the seawater is separated or knocked out of the exhaust stream and returned back to the sea.
  • Nitrogen oxides (NO x ) are also absorbed to some extent by the seawater scrubbing process, so seawater scrubbing offers the potential advantage of reducing the atmospheric emissions of both NO x and5 SO x .
  • the primary shortcoming in using seawater scrubbing for NO x reduction is that the seawater can readily absorb nitrogen dioxide (NO 2 ), but not nitric oxide (NO). Since the majority of NO x from a diesel engine is NO and not NO 2 , the NO needs to be converted into NO 2 before it can be effectively absorbed by the seawater and converted to nitrates.
  • a wet scrubbing subsystem is used to reduce the atmospheric emissions of both nitrogen oxides (NO x ) and sulfur oxides (SO x ) from an engine exhaust stream.
  • NO x nitrogen oxides
  • SO x sulfur oxides
  • the engine exhaust stream is first directed through a catalytic oxidation device that converts NO to NO 2 .
  • the wet scrubbing subsystem can conveniently employ seawater scrubbing.
  • the wet scrubbing subsystem can involve a one-stage or multi-stage scrubbing process.
  • the oxidation catalysts in the catalytic oxidation device tend to become poisoned by sulfur species in the engine exhaust stream that originate from the fuel source, so it is desirable to periodically regenerate the device.
  • a syngas generator can be employed to produce a syngas stream that can be used to regenerate the oxidation catalyst.
  • An exhaust stream flow diverter and syngas flow distribution device can employed to direct the various streams to enable simultaneous catalyst regeneration and exhaust after-treatment.
  • a control module can be employed to control the various devices within the exhaust after-treatment system.
  • embodiments of a method of operating an engine system comprising an engine, an exhaust after-treatment system and at least one wet scrubbing device, comprise:
  • the wet scrubbing device can comprise a seawater scrubber.
  • there is a first and second seawater scrubber and the method comprises directing the engine exhaust gas from the catalytic oxidation device through the first seawater scrubber and then through the second seawater scrubber.
  • the method can further involve operating a syngas generator to produce a syngas stream. At least a portion of the syngas stream can be at least periodically directed to the catalytic oxidation device to regenerate the device.
  • the engine system comprises more than one catalytic oxidation device (for example, a first and second catalytic oxidation device) the method can comprise selectively directing syngas from the syngas generator to the first catalytic oxidation device while at the same time directing the at least at portion of the engine exhaust stream to the second catalytic oxidation device and vice versa so that it is possible to regenerate one device while another continues to perform oxidation of NO in the engine exhaust stream.
  • the syngas generator is supplied with a fuel and an oxidant stream, and in some embodiments a water-containing stream.
  • the fuel can conveniently be supplied from the same fuel supply that is used to supply the engine.
  • the oxidant stream can comprises air and/or at least a portion of the engine exhaust stream.
  • Embodiments of a combustion engine and exhaust after- treatment system comprise: [0029] (a) an engine and a fuel tank and fuel line for directing fuel to the engine;
  • At least one catalytic oxidation device fluidly connected to at least periodically receive engine exhaust from the engine via the engine exhaust stream line, to produce a treated engine exhaust stream;
  • At least one wet scrubbing device located downstream of the at least one catalytic oxidation device and fluidly connected to receive the treated engine exhaust from the at least one catalytic oxidation device.
  • the at least one wet scrubbing device can comprise a seawater scrubber, and in some embodiments comprises at least a first and second seawater scrubber, wherein the first seawater scrubber is connected to receive the treated engine exhaust from the at least one catalytic oxidation device, and the second seawater scrubber is connected to receive the treated engine exhaust from the first seawater scrubber.
  • the combustion engine and exhaust after-treatment system can further comprise a syngas generator fluidly connected to at least periodically supply syngas to each the catalytic oxidation device.
  • the system can comprise at least a first and second catalytic oxidation device, and optionally at least one exhaust stream flow diverter for selectively directing the exhaust 5 stream to the first or second catalytic oxidation device.
  • the system can comprise at least one syngas flow distribution device for selectively directing syngas to the first or second catalytic oxidation device.
  • FIG. 1 is a schematic diagram of an embodiment of a diesel engine system having an exhaust after-treatment system that employs oxidation catalysts, a syngas generator and seawater scrubbers.
  • a combustion engine system employs an after-treatment system that results in reduced atmospheric emissions of nitrogen oxides (NO x ) and sulfur oxides (SO x ).
  • the present system and method comprise:
  • a wet scrubbing subsystem that employs one or more wet scrubbers (such as seawater scrubbers) for introducing water into the engine exhaust stream downstream of the catalytic oxidation device.
  • the wet scrubbing subsystem supplies, meters, and introduces the water into the engine exhaust stream at one or more locations.
  • the wet scrubber absorbs NO 2 and SO x from the engine exhaust stream, and then releases the water.
  • preferred embodiments of the present system and method can further comprise some or all of the following:
  • control module that employs one or more controllers and software for controlling various components of the exhaust after-treatment system, such as the syngas generator system, exhaust gas flow diverter system, wet scrubbing subsystem, water supply and water exhaust system.
  • FIG. 1 is a schematic illustration of a marine diesel engine system 10 comprising an exhaust after-treatment system that employs two catalytic oxidation devices and a pair of seawater scrubbers to remediate the engine exhaust stream, and a syngas generator to produce syngas to regenerate the catalyst beds in the catalytic oxidation devices.
  • fuel tank 11 supplies diesel fuel via fuel conduit 12 and fuel conduit 13 to combustion engine 14.
  • Combustion engine 14 can be, for example, a reciprocating piston engine which comprises one or more cylinders, a Wankel rotary engine comprising one or more rotors, a gas turbine, or another type of engine. Ambient air is drawn through an air intake subsystem (not shown in FIG. 1) and is introduced into engine 14.
  • engine exhaust gas flow diverter 18 receives control signals from control module 42 (control lines not shown in FIG. 1) and typically operates in one of three positions at a given time. In the first position, diverter 18 directs the engine exhaust stream via conduit 20 to catalyst bed 22, while limiting or preventing the exhaust stream from flowing via conduit 19 to catalyst bed 21. In catalyst bed 22, NO in the exhaust stream is oxidized to NO 2 . At the same time catalyst bed 21 can be regenerated. The treated exhaust stream then flows from catalyst bed 22 via conduit 23 into primary scrubber 24.
  • flow diverter 18 allows the engine exhaust stream to flow via conduit 19 to catalyst bed 21, and via conduit 20 to catalyst bed 22.
  • the treated exhaust stream then flows from catalyst bed 21 and catalyst bed 22 via conduit 23 into primary scrubber 24.
  • diverter 18 directs the engine exhaust stream via conduit 19 to catalyst bed 21, while limiting or preventing the exhaust stream from flowing via conduit 20 to catalyst bed 22.
  • NO in the exhaust stream is oxidized to NO 2 .
  • catalyst bed 22 can be regenerated.
  • the treated exhaust stream flows from catalyst bed 21 via conduit 23 into primary scrubber 24.
  • An optional NO x sensor (not shown in FIG. 1) can be located in exhaust conduit 23, to aid in the control of flow diverter 18.
  • seawater is introduced and sprayed into the exhaust stream via first seawater conduit 39.
  • the cold seawater mixes with and cools the exhaust stream, adsorbing the NO x (which has largely been catalytically oxidized to NO 2 in bed 21 and/or 22) and SO x from the stream.
  • Primary scrubber 24 then separates the seawater from the exhaust stream, draining the seawater back into the sea through seawater drain conduit 40.
  • the exhaust stream exits primary scrubber 24 and flows via conduit 25 into main scrubber 26 for the secondary scrubbing process.
  • Seawater is introduced and sprayed into the exhaust stream via second seawater conduit 38.
  • the seawater mixes with and further cools the exhaust stream, further adsorbing the NO 2 and SO x from the stream. Particulate matter is also captured in the seawater in scrubbers 24 and 26. Main scrubber 26 then separates the seawater from the exhaust stream, draining the seawater back into the sea through seawater drain conduit 41. The treated and scrubbed exhaust stream is then released to the surrounding environment via exhaust conduit 27.
  • Seawater is drawn from the sea through seawater intake conduit 36 and seawater pump 37.
  • the seawater stream is directed to the primary and main scrubbers 24 and 26 through seawater conduit 39 and seawater conduit 38, respectively.
  • Additional optional flow control, distribution devices and sensors are not shown in FIG. 1.
  • Such flow control devices can receive control signals from control module 42 to meter the flow of seawater to each of the scrubbers 24 and 26.
  • fuel tank 11 also supplies diesel fuel to syngas generator 31 via fuel conduit 12, metering pump 28 and fuel conduit 29.
  • Metering pump 28 receives control signals from control module 42.
  • the engine exhaust stream exits combustion engine 14 into exhaust manifold 15. At least a portion of the engine exhaust stream can be directed to syngas generator 31 via exhaust conduit 30.
  • Syngas generator 31 mixes and converts the fuel and engine exhaust stream into product syngas.
  • Product syngas exits syngas generator 31 and flows via syngas conduit 32 to syngas flow distribution valve 33.
  • Syngas flow distribution valve 33 receives control signals from control module 42, which then directs the flow of syngas to either syngas conduit 35 and catalyst bed 21 , or syngas conduit 34 and catalyst bed 22, to regenerate the catalyst bed.
  • At least one oxidizing catalyst bed is employed to convert the nitric oxide (NO) in the engine exhaust gas stream into nitrogen dioxide (NO 2 ).
  • the increase in the amount OfNO 2 increases the NO x absorption capacity of the downstream seawater scrubbing process, thereby reducing the level of atmospheric NO x emissions.
  • the oxidation catalysts can, for example, comprise a platinum (Pt) catalyst and an alumina (AI 2 O 3 ) carrier on a monolith substrate.
  • a catalyst formulation comprising one or more platinum group metals such as platinum (Pt) or rhodium (Rh) can be employed.
  • the catalyst composition, catalyst particle size, catalyst dispersion, substrate geometry, and other catalyst bed parameters can be optimized for NO oxidation, catalyst regeneration and low pressure loss across the catalyst bed.
  • the temperature of the catalyst bed is maintained within a desired range, for example 350° ⁇ 50 0 C, during the exhaust stream oxidation process and normal engine duty.
  • At least two oxidizing catalyst beds are employed, so that one can be actively oxidizing NO to NO 2 while the other is being regenerated.
  • an exhaust gas flow diverter directs the engine exhaust stream through one catalyst bed while limiting or stopping the flow to the other. Under some operating conditions, the engine exhaust stream can be directed through more than one catalyst bed simultaneously.
  • the flow diverter can be controlled by a control module which can switch the catalyst beds between operating to oxidize NO and being regenerated, for example, based on preprogrammed algorithms, or in response to monitored parameters in the system.
  • Various configurations can be used for the two or more catalyst beds. For example, multiple catalyst beds can be contained in a single housing or enclosure, with internally separated conduits.
  • the enclosure can be rotated, exposing at least one catalyst bed to the engine exhaust stream allowing for NO oxidation, while one or more other catalyst beds are simultaneously regenerated.
  • a rotating gas distribution manifold can be used in conjunction with a stationary single enclosure configuration containing multiple catalyst beds. The rotating gas distribution manifold can switch the catalyst beds between the NO oxidation process and regeneration process.
  • sulfur originating from the engine fuel and oil can be converted into sulfur compounds such as, for example, sulfur trioxide (SO 3 ) and/or sulfuric acid (H 2 SO-O, which are generally preferentially adsorbed by the oxidation catalyst.
  • SO 3 sulfur trioxide
  • H 2 SO-O sulfuric acid
  • syngas is periodically introduced into the catalyst bed to regenerate the catalyst, restoring its desired performance.
  • the syngas is introduced within a specific range for example, 0.95 to 1.0 stoichiometry, or under a slight oxygen deficient condition. If the syngas introduction rate is below a threshold value, the regeneration rate can be reduced.
  • H 2 S hydrogen sulfide
  • the temperature of the catalyst bed is increased during the regeneration process, for example to within the range 450° to 500 0 C, to increase the regeneration rate.
  • the temperature of the catalyst bed can be increased and controlled by the metering the amounts of syngas and engine exhaust gas supplied to bed.
  • the catalyst beds can be regenerated using other regenerating methods, agents and/or combinations thereof.
  • thermal regeneration without the use of a regenerating agent can be used.
  • Hydrogen (H 2 ) or carbon monoxide (CO) alone, or various other gaseous or liquid fuels or hydrocarbons can be used as the regenerating agent.
  • syngas (or other regenerating agent) is preferably generated on-board, due to challenges related to on-board storage, maintenance and the current absence of a re-fueling infrastructure for syngas or other suitable regenerating agents. This can be accomplished with the use of a fuel processor, such as a syngas generator.
  • a syngas generator converts a fuel and a portion of the engine exhaust stream into syngas.
  • the engine exhaust stream typically contains oxygen (O 2 ), water (H 2 O), carbon dioxide (CO 2 ), nitrogen (N2) and sensible heat, which can be useful for the production of syngas.
  • an air stream can be supplied to the SGG in combination with or in lieu of the engine exhaust stream.
  • the air stream can be supplied from an air compressor which supplies inlet air to the engine, for example turbo- compressor or supercharger, or from a separate air supply subsystem with an air compressor (not shown in FIG. 1).
  • the fuel used by the SGG can conveniently be the same fuel that is used in the combustion engine.
  • the SGG design is preferably non-catalytic, and the SGG is preferably operated continuously while the combustion engine is operating to reduce thermal cycling of the SGG and to reliably provide syngas when needed.
  • the syngas generator can alternatively be a catalytic type of reformer such as a partial oxidation or auto-thermal reformer. Seawater can be distilled to supply water to an auto-thermal type reformer in marine applications.
  • a syngas flow distribution device such as a valve, is employed to distribute the product syngas from the SGG to the various catalyst beds (and optionally to other components of the system) at the appropriate time.
  • the SGG and syngas flow distribution device can be controlled by a control module.
  • a one- stage scrubbing process involving a single seawater scrubber can be employed, however in preferred embodiments of the present system and method, a two-stage seawater scrubbing process is employed to reduce the amount OfNO x and SO x in the engine exhaust stream.
  • the exhaust stream is directed through a primary seawater scrubbing process before proceeding onto a secondary or main seawater scrubbing process.
  • Seawater is pumped from the sea, optionally metered, and sprayed into the engine exhaust stream to increase the contact area between the seawater and exhaust gas, thereby increasing the heat transfer and gas absorption rates.
  • the seawater can be metered and introduced at a rate which cools the exhaust gas stream to within a temperature range that enhances the NO x and SO x absorption rate while reducing the formation of visible fog released into the atmosphere. Reducing the exhaust gas temperature using the seawater offers several other advantages. For example, it can reduce the exhaust system volume, reduce the temperature of the exhaust conduits lessening the potential of accidents and injuries, reduce the tendency for corrosion in the exhaust gas system, and reduce the exhaust gas infrared signature.
  • the seawater scrubber also functions to separate the introduced seawater from the exhaust stream, allowing the seawater to be returned to the sea.
  • a seawater scrubber can also function as a silencer, providing noise attenuation.
  • a control module can be employed to control the seawater introduction rate into the engine exhaust stream in each scrubber.
  • a metering pump can be used to meter the amount of seawater introduced into the exhaust gas stream in each scrubber.
  • a control module with various sensors and preprogrammed control logic is employed to control the exhaust after- treatment system and devices.
  • the control module can control various functions, for example, the operation of the syngas generator, the rate of the syngas generation, distribution of product syngas, distribution of the engine exhaust stream, regeneration of catalyst beds, the seawater scrubbing water introduction rate, and seawater release.
  • the control module can employ various sensors such as, temperature, pressure, flow rate, location, speed, nitric oxide (NO) and other gas sensors.
  • NO nitric oxide
  • the exhaust after-treatment components are made from titanium or a titanium alloy, offering an increase in resistance to corrosion.
  • the combustion engine system can comprise a combustion engine or burner, for example an internal combustion engine or a gas turbine.
  • the combustion engine system may or may not employ a turbo-compressor, supercharger or exhaust gas recirculation (EGR).
  • EGR exhaust gas recirculation
  • the combustion engine can be fueled by diesel, gas oil, marine gas oil, intermediate fuel oil, fuel oil, residual fuel oil, gasoline, kerosene, natural gas, liquid propane gas (LPG), jet fuel, coal or other suitable fuels, depending on the application.
  • Additional exhaust after-treatment devices can be employed in the system, such as a diesel oxidation catalyst device (DOC) for reducing the level of CO and unburned hydrocarbon, and/or a diesel particulate filter (DPF) for reducing particulate matter in the exhaust stream.
  • DOC diesel oxidation catalyst device
  • DPF diesel particulate filter
  • Syngas can optionally be directed to the DOC and/or DPF to enhance the effectiveness of the devices at various times, for example, by elevating the temperature of the device to the desired operating temperature.
  • the present system and method is particularly suited for use in marine propulsion and/or power generation applications (as used herein, reference to "marine applications” includes freshwater applications as well sea- or ocean-based applications).
  • marine applications includes freshwater applications as well sea- or ocean-based applications.
  • embodiments of the present system and method can be used in other industries, for example stationary power generation, metal smelting and oil refining processes and in other motive and stationary applications for example power generation, off shore oil, gas drilling or production platforms.

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

Abstract

Un sous-système de lavage humide réduit les émissions atmosphériques d'oxydes d'azote (NOx) et d'oxydes de soufre (SOx) provenant d'un courant d'échappement de moteur. Le courant d'échappement est tout d'abord dirigé à travers un dispositif d'oxydation catalytique qui convertit le NO en NO2. Dans des applications marines, le sous-système de lavage humide peut employer un lavage à l'eau de mer. Le sous-système de lavage par voie humide peut mettre en jeu un procédé de lavage à un stade ou à plusieurs stades. Les catalyseurs d'oxydation dans le dispositif d'oxydation catalytique ont tendance à s'empoisonner par l'espèce soufre dans le courant d'échappement. Si plus d'un dispositif d'oxydation catalytique ou lit catalytique est utilisé, un dispositif ou lit peut être régénéré alors qu'un autre continue à oxyder NO dans le courant d'échappement. Un générateur de syngas peut être employé pour produire un courant de syngas pour l'utilisation dans la régénération du catalyseur d'oxydation. Un dispositif de déviation de l'écoulement du courant d'échappement et un dispositif de distribution de l'écoulement de syngas peuvent être employés pour diriger les divers courants pour permettre une régénération du catalyseur et un post-traitement d'échappement simultanés.
PCT/CA2008/000377 2007-02-27 2008-02-26 Système de réduction des émissions à l'aide d'un lavage humide Ceased WO2008104070A1 (fr)

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GB2469319A (en) * 2009-04-08 2010-10-13 Krystallon Ltd Exhaust treatment for a marine engine
EP2380652A1 (fr) * 2010-04-23 2011-10-26 General Electric Company Système et procédé de contrôle et de réduction d'émissions NOx
EP2380654A1 (fr) * 2010-04-23 2011-10-26 General Electric Company Système et procédé de contrôle et de réduction des émissions NOx
WO2012012881A1 (fr) * 2010-07-26 2012-02-02 Nxtgen Emission Controls Inc. Convertisseur de combustible présentant un collecteur de montage
WO2012113977A1 (fr) * 2011-02-23 2012-08-30 Wärtsilä Finland Oy Système d'épuration permettant de traiter les gaz d'échappement dans un navire et procédé de traitement des gaz d'échappement dans le système d'épuration d'un navire
WO2012117233A1 (fr) * 2011-02-28 2012-09-07 Oceanox Limited Épuration de gaz d'échappement
US9387438B2 (en) 2014-02-14 2016-07-12 Tenneco Automotive Operating Company Inc. Modular system for reduction of sulphur oxides in exhaust
JP2016164071A (ja) * 2016-05-30 2016-09-08 ヤンマー株式会社 船舶における排気ガス浄化装置
WO2020240549A1 (fr) * 2019-05-30 2020-12-03 Ariel Scientific Innovations Ltd. Système et procédé d'oxydation catalytique et d'épuration par voie humide de nox et de sox simultanément à partir d'un gaz de combustion dans des moteurs de navire
US11118492B1 (en) 2020-04-27 2021-09-14 Stec Technology, Inc. Reactive cyclic induction system and method for reducing pollutants in marine diesel exhaust

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Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2469319A (en) * 2009-04-08 2010-10-13 Krystallon Ltd Exhaust treatment for a marine engine
EP2380652A1 (fr) * 2010-04-23 2011-10-26 General Electric Company Système et procédé de contrôle et de réduction d'émissions NOx
EP2380654A1 (fr) * 2010-04-23 2011-10-26 General Electric Company Système et procédé de contrôle et de réduction des émissions NOx
WO2012012881A1 (fr) * 2010-07-26 2012-02-02 Nxtgen Emission Controls Inc. Convertisseur de combustible présentant un collecteur de montage
WO2012113977A1 (fr) * 2011-02-23 2012-08-30 Wärtsilä Finland Oy Système d'épuration permettant de traiter les gaz d'échappement dans un navire et procédé de traitement des gaz d'échappement dans le système d'épuration d'un navire
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GB2501663A (en) * 2011-02-28 2013-10-30 Oceanox Ltd Exhaust scrubbing
WO2012117233A1 (fr) * 2011-02-28 2012-09-07 Oceanox Limited Épuration de gaz d'échappement
GB2501663B (en) * 2011-02-28 2017-09-27 Galor Holness Nicholas Exhaust scrubbing
US9387438B2 (en) 2014-02-14 2016-07-12 Tenneco Automotive Operating Company Inc. Modular system for reduction of sulphur oxides in exhaust
JP2016164071A (ja) * 2016-05-30 2016-09-08 ヤンマー株式会社 船舶における排気ガス浄化装置
WO2020240549A1 (fr) * 2019-05-30 2020-12-03 Ariel Scientific Innovations Ltd. Système et procédé d'oxydation catalytique et d'épuration par voie humide de nox et de sox simultanément à partir d'un gaz de combustion dans des moteurs de navire
US11118492B1 (en) 2020-04-27 2021-09-14 Stec Technology, Inc. Reactive cyclic induction system and method for reducing pollutants in marine diesel exhaust

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