EP0280678B1 - Method for reducing nitric oxide emissions in exhaust gases from diesel engines - Google Patents

Method for reducing nitric oxide emissions in exhaust gases from diesel engines Download PDF

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Publication number
EP0280678B1
EP0280678B1 EP86905301A EP86905301A EP0280678B1 EP 0280678 B1 EP0280678 B1 EP 0280678B1 EP 86905301 A EP86905301 A EP 86905301A EP 86905301 A EP86905301 A EP 86905301A EP 0280678 B1 EP0280678 B1 EP 0280678B1
Authority
EP
European Patent Office
Prior art keywords
exhaust gases
diesel engine
nitric oxide
recirculated
conducted
Prior art date
Legal status (The legal status 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 status listed.)
Expired - Lifetime
Application number
EP86905301A
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German (de)
French (fr)
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EP0280678A1 (en
Inventor
Harri Johannes HARJUNPÄÄ
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Outokumpu Oyj
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Outokumpu Oyj
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Publication of EP0280678A1 publication Critical patent/EP0280678A1/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D21/00—Controlling engines characterised by their being supplied with non-airborne oxygen or other non-fuel gas
    • F02D21/06—Controlling engines characterised by their being supplied with non-airborne oxygen or other non-fuel gas peculiar to engines having other non-fuel gas added to combustion air
    • F02D21/08—Controlling engines characterised by their being supplied with non-airborne oxygen or other non-fuel gas peculiar to engines having other non-fuel gas added to combustion air the other gas being the exhaust gas of engine
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
    • F02M26/14—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the exhaust system
    • F02M26/15—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the exhaust system in relation to engine exhaust purifying apparatus
    • 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
    • F02B3/00—Engines characterised by air compression and subsequent fuel addition
    • F02B3/06—Engines characterised by air compression and subsequent fuel addition with compression ignition

Definitions

  • the present invention relates to a method for reducing nitric oxide emissions in the exhaust gases from diesel engines by means of conducting water into the engine and by recirculating the exhaust gases, according to the first part of claim 1.
  • a drawback in the use of combustion engines such as diesel engines arises in the form of harmful compounds contained in exhaust gases. Among them, the most dangerous and the most difficult to eliminate are nitric oxides. The amount of created nitric oxides is comparable to the temperature prevailing in the combustion chamber, as well as to the oxygen content of the explosion gas.
  • a previously known method for reducing the amount of nitric oxides is to lower the combustion temperature by adding water into the combustion chamber of the diesel engine.
  • the water addition can be carried out in various ways: according to the DE Patent Application No. 31 44472, water is sprayed separately into the combustion chamber. In connection to the water addition, the water condensed from the exhaust gases can also be utilized; this water is conducted into the combustion chamber by means of spraying, as is the case with water additions in the apparatus introduced in the DE Patent Application No. 2851 232.
  • the supplied water is fed directly into the suction duct ( D E Patent Application No. 28 31 694), or the water is first dispersed in a finer form by feeding the fresh combustion air through a liquid volume and further into the suction duct (DE Patent Applications Nos.
  • the water to be conducted into the combustion chamber can also be first evaporated by means of a thermal exchanger, so that the heating is carried out by conducting the hot exhaust gases through a water container.
  • the resulting steam is then conducted into the suction duct, whereas the exhaust gases are discharged into the open air.
  • the evaporation method is introduced for instance in the SE Patent Publication No. 428587 and DE Patent Applications Nos. 21 54755 and 2604050.
  • Another prior art method for diminishing the nitric oxide emissions of a diesel engine is partial recirculation of the exhaust gases.
  • the exhaust gas is recirculated back into the engine in dry form.
  • the recirculated exhaust gas functions as an inert gas and thus reduces the oxygen content of the gas contained in the combustion chamber. Simultaneously the production of nitric oxide is also diminished.
  • the regulation of recirculated exhaust gases is also difficult to control.
  • the recirculated exhaust gases are cooled off for instance in order to reduce thermal strain.
  • the object of the present invention is to eliminate some of the drawbacks of the prior art and to realize an improved, more secure method for reducing the nitric oxide emissions of diesel engine exhaust gases, by means of applying the recirculation of cooled exhaust gases combined to the aqueous vapours resulting from the wet cleaning of the exhaust gases.
  • the features of the invention are apparent from the appended patent claim 1.
  • the exhaust gases from the engine are conducted through a catalyzer, advantageously for reducing the amount of carbon monoxide and hydrocarbons, before directing the gases into the wet cleaner.
  • the exhaust gases are simultaneously washed and cooled.
  • the cooled exhaust gases are further conducted, humidified by the vapours created in the washing, back into the suction duct of the diesel engine.
  • the recirculated exhaust gas, the quantity whereof is about 20% of the whole exhaust gas volume, is mixed in the general suction air flow by means of a mixer valve and a nozzle, whereby the mixture ratio can be maintained constant irrespective of the charge and the speed of rotation.
  • the recirculation of the exhaust gases, the cooling of the recirculated exhaust gases, and the water additions into the combustion chamber, as well as the regulation of the volume of the returned gas, can thus all be combined.
  • the exhaust gases from the diesel engine 1 are conducted, through the catalyzer 2, into the wet cleaner 3.
  • the exhaust gases are cooled and washed.
  • the major part of the exhaust gases are discharged through the exhaust pipe 4.
  • the damp exhaust gas to be recirculated according to the invention is conducted, through the return pipe 5, into the suction system 10 of the diesel engine.
  • the recirculated exhaust gas supplied from the return pipe 5, which gas is humidified by the steam created in the cleaner 3, is conducted, via the recirculation valve 6, back to the recirculation nozzle 7.
  • the suction air of the diesel engine, drawn in through the air purifier 8, is also conducted to the nozzle 7.
  • the mixture of recirculated exhaust gas and pure suction air thus created in the nozzle 7 is further conducted, via the suction duct 10 of the diesel engine, into the combustion chamber 9, wherefrom the created exhaust gases are further conducted to the catalyzer 2.
  • the recirculation valve 6 and the nozzle 7 there is achieved and advantageous regulation of the volume of the recirculated exhaust gas, so that a profitable mixture ratio between the suction air and the recirculated exhaust gas is maintained irrespective of any possible changes in the charge or in the speed of rotation.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Exhaust-Gas Circulating Devices (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)
  • Treating Waste Gases (AREA)

Abstract

Method for reducing the nitric oxide emissions of the exhaust gases from a diesel engine by means of a controlled recirculation of the exhaust gases, which are cooled off and humidified in a water bath. According to the invention, the exhaust gases created in the diesel engine (1) are conducted into the wet cleaner (3), and part of the exhaust gases conducted into the wet cleaner (3) are returned to the suction duct (10) of the diesel engine, so that the amount of the recirculated exhaust gas is maintained constant with respect to the total exhaust gas volume.

Description

  • The present invention relates to a method for reducing nitric oxide emissions in the exhaust gases from diesel engines by means of conducting water into the engine and by recirculating the exhaust gases, according to the first part of claim 1.
  • A drawback in the use of combustion engines such as diesel engines arises in the form of harmful compounds contained in exhaust gases. Among them, the most dangerous and the most difficult to eliminate are nitric oxides. The amount of created nitric oxides is comparable to the temperature prevailing in the combustion chamber, as well as to the oxygen content of the explosion gas.
  • A previously known method for reducing the amount of nitric oxides is to lower the combustion temperature by adding water into the combustion chamber of the diesel engine. The water addition can be carried out in various ways: according to the DE Patent Application No. 31 44472, water is sprayed separately into the combustion chamber. In connection to the water addition, the water condensed from the exhaust gases can also be utilized; this water is conducted into the combustion chamber by means of spraying, as is the case with water additions in the apparatus introduced in the DE Patent Application No. 2851 232. The supplied water is fed directly into the suction duct ( D E Patent Application No. 28 31 694), or the water is first dispersed in a finer form by feeding the fresh combustion air through a liquid volume and further into the suction duct (DE Patent Applications Nos. 26 01 456 and 26 33 639). The water to be conducted into the combustion chamber can also be first evaporated by means of a thermal exchanger, so that the heating is carried out by conducting the hot exhaust gases through a water container. The resulting steam is then conducted into the suction duct, whereas the exhaust gases are discharged into the open air. The evaporation method is introduced for instance in the SE Patent Publication No. 428587 and DE Patent Applications Nos. 21 54755 and 2604050.
  • The drawback in the aforementioned methods for feeding water into the combustion chamber is the fact that the purchase expenses of the equipment needed for adjusting the water supply are very high. Moreover, its maintenance requires special care, which partly also increases the operational costs.
  • Another prior art method for diminishing the nitric oxide emissions of a diesel engine is partial recirculation of the exhaust gases. In certain prior art methods, for instance in those introduced in the SE Patent Publication No. 404068 and DE Patent Application 2443897, the exhaust gas is recirculated back into the engine in dry form. The recirculated exhaust gas, the quantity whereof is advantageously 20% of the suction air volume, functions as an inert gas and thus reduces the oxygen content of the gas contained in the combustion chamber. Simultaneously the production of nitric oxide is also diminished. However, the regulation of recirculated exhaust gases is also difficult to control. Moreover, it is preferable that the recirculated exhaust gases are cooled off for instance in order to reduce thermal strain.
  • The method of recirculating damp exhaust gases is utilized in the fuel evaporator according to the US Patent No. 2430852. In that case, however, the recirculated damp exhaust gases are fed, together with the gasified fuel, into the suction space of a combustion engine. Consequently, the suggested arrangement cannot be applied for instance for diesel engines, where the fuel is sprayed into the combustion chamber.
  • In an apparatus according to the DE Patent Application 2 504308, a part of exhaust gases is conducted to the wet cleaner wherefrom the washed and cooled exhaust gases are recirculated. The amount of these exhaust gases recirculated according the DE Application is in no way maintained constant and this recirculation is not utilized, either, when the motor is operating with idling or with full load. Further, a safety valve is required in the apparatus of the DE Patent Application 2504308 and in that apparatus distilled water is used and the delivery of that kind of water is in many cases difficult.
  • The object of the present invention is to eliminate some of the drawbacks of the prior art and to realize an improved, more secure method for reducing the nitric oxide emissions of diesel engine exhaust gases, by means of applying the recirculation of cooled exhaust gases combined to the aqueous vapours resulting from the wet cleaning of the exhaust gases. The features of the invention are apparent from the appended patent claim 1.
  • According to an embodiment of the invention, the exhaust gases from the engine are conducted through a catalyzer, advantageously for reducing the amount of carbon monoxide and hydrocarbons, before directing the gases into the wet cleaner. In the wet cleaner, the exhaust gases are simultaneously washed and cooled. The cooled exhaust gases are further conducted, humidified by the vapours created in the washing, back into the suction duct of the diesel engine. The recirculated exhaust gas, the quantity whereof is about 20% of the whole exhaust gas volume, is mixed in the general suction air flow by means of a mixer valve and a nozzle, whereby the mixture ratio can be maintained constant irrespective of the charge and the speed of rotation.
  • When employing the method of the invention, the recirculation of the exhaust gases, the cooling of the recirculated exhaust gases, and the water additions into the combustion chamber, as well as the regulation of the volume of the returned gas, can thus all be combined.
  • In the following the invention is explained with reference to the appended drawing, where
    • Figure 1 is a schematical illustration of a preferred embodiment of the invention, and
    • Figure 2 illustrates the superiority of the damp recirculation method of the invention, as compared to the prior art dry recirculation method.
  • According to figure 1, the exhaust gases from the diesel engine 1 are conducted, through the catalyzer 2, into the wet cleaner 3. In the wet cleaner 3, the exhaust gases are cooled and washed. The major part of the exhaust gases are discharged through the exhaust pipe 4. The damp exhaust gas to be recirculated according to the invention is conducted, through the return pipe 5, into the suction system 10 of the diesel engine. The recirculated exhaust gas supplied from the return pipe 5, which gas is humidified by the steam created in the cleaner 3, is conducted, via the recirculation valve 6, back to the recirculation nozzle 7. The suction air of the diesel engine, drawn in through the air purifier 8, is also conducted to the nozzle 7. The mixture of recirculated exhaust gas and pure suction air thus created in the nozzle 7 is further conducted, via the suction duct 10 of the diesel engine, into the combustion chamber 9, wherefrom the created exhaust gases are further conducted to the catalyzer 2. By means of the recirculation valve 6 and the nozzle 7, there is achieved and advantageous regulation of the volume of the recirculated exhaust gas, so that a profitable mixture ratio between the suction air and the recirculated exhaust gas is maintained irrespective of any possible changes in the charge or in the speed of rotation.
  • In figure 2, where the symbol NOx refers to the sum of the nitric oxides NO and NOz, the damp recirculation of the exhaust gases according to the invention is compared to the prior art dry recirculation, when the recirculated portion is 20% of the total exhaust gas volume. The nitric oxide content curves, drawn in figure 2, are illustrated as a function of the mean pressure of the engine. It is apparent from figure 2 that while employing the method of the invention (curves A), the total amount NOX of the nitric oxides is essentially reduced compared to the so-called dry recirculation method (curves B) of the prior art. The superiority of the damp recirculation method is also obvious when comparing the content of curves A to the curves C repressing such prior art method where water is conduced into the diesel engine, but the exhaust gases are not recirculated. According to curves A, the total amount NOx of the nitric oxides is reduced, and the component N02, considered to be the most dangerous among the nitric oxides, is almost completely eliminated from the exhaust gases when applying the method of the invention, while the mean pressure of the engine is increased.

Claims (3)

1. A method for reducing the nitric oxide emissions of exhaust gases from a combustion engine by means of water additions into the combustion chamber of the engine and recirculation of the exhaust gases, characterized in that the exhaust gases created in the diesel engine (1 ) are conducted into a wet cleaner (3), and that part of the washed and cooled gases discharged from the wet cleaner (3) are returned to the suction system (10) of the diesel engine (1), in such a way that the volume of the recirculated exhaust gas is maintained constant with respect to the total gas volume of the diesel engine (1).
2. The method of claim 1, characterized in that the recirculated exhaust gases contain the water to be fed into the combustion chamber of the diesel engine (1).
3. The method of claim 1 or 2, characterized in that the amount of recirculated exhaust gases is about 20% of the total exhaust gas volume of the diesel engine (1).
EP86905301A 1986-09-08 1986-09-08 Method for reducing nitric oxide emissions in exhaust gases from diesel engines Expired - Lifetime EP0280678B1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/FI1986/000094 WO1988001016A1 (en) 1986-09-08 1986-09-08 Method for reducing nitric oxide emissions in exhaust gases from diesel engines

Publications (2)

Publication Number Publication Date
EP0280678A1 EP0280678A1 (en) 1988-09-07
EP0280678B1 true EP0280678B1 (en) 1990-01-31

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EP86905301A Expired - Lifetime EP0280678B1 (en) 1986-09-08 1986-09-08 Method for reducing nitric oxide emissions in exhaust gases from diesel engines

Country Status (6)

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EP (1) EP0280678B1 (en)
JP (1) JPH01500765A (en)
DE (1) DE3668665D1 (en)
FI (1) FI73297C (en)
RU (1) RU1839695C (en)
WO (1) WO1988001016A1 (en)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DK170218B1 (en) * 1993-06-04 1995-06-26 Man B & W Diesel Gmbh Large pressurized diesel engine
US5694908A (en) * 1996-05-08 1997-12-09 Hsu; Chih-Cheng Auxiliary water-supply sytem for an internal combustion engine
GB2313155B (en) * 1996-05-08 1998-06-24 Hsu Chih Cheng An auxiliary water supply system for an internal combustion engine
KR100720876B1 (en) * 2002-05-21 2007-05-22 맨 디젤 에이/에스 Large supercharged internal combustion engine
JP5787500B2 (en) * 2010-08-24 2015-09-30 三菱重工業株式会社 Engine exhaust gas purification device and ship

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1632285A (en) * 1923-12-06 1927-06-14 John J Georgi Gas generator
US2737936A (en) * 1953-02-09 1956-03-13 Clement S Clarke Internal combustion engine
US2870758A (en) * 1958-01-07 1959-01-27 Fred A Standiford Decontamination system
US3139873A (en) * 1963-03-19 1964-07-07 Donald L Gardner Exhaust and water injector for internal combustion engines
SE7703011L (en) * 1977-03-17 1978-09-18 Lindstroem O KIT AND DEVICE FOR OPERATION OF COMBUSTION ENGINES

Also Published As

Publication number Publication date
EP0280678A1 (en) 1988-09-07
FI73297B (en) 1987-05-29
FI850966A0 (en) 1985-03-12
RU1839695C (en) 1993-12-30
DE3668665D1 (en) 1990-03-08
FI73297C (en) 1987-09-10
WO1988001016A1 (en) 1988-02-11
JPH01500765A (en) 1989-03-16
FI850966L (en) 1986-09-13

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