US20090211231A1 - Exhaust gas treatment system for an internal combustion engine - Google Patents
Exhaust gas treatment system for an internal combustion engine Download PDFInfo
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- US20090211231A1 US20090211231A1 US12/342,412 US34241208A US2009211231A1 US 20090211231 A1 US20090211231 A1 US 20090211231A1 US 34241208 A US34241208 A US 34241208A US 2009211231 A1 US2009211231 A1 US 2009211231A1
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- nox
- exhaust gas
- treatment system
- gas treatment
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- 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
- F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
- F01N3/0814—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts
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- 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
- F01N2240/28—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 plasma reactor
Definitions
- the present invention relates to an exhaust gas treatment system for an internal combustion engine.
- exhaust gas is produced as a result of the combustion of fuel and discharged into the atmosphere.
- the exhaust gas contains various substances such as particulate matter (PM) including carbide particles, hydrocarbons (HC), sulfur oxides (SOx: SO, SO 2 ), nitrogen oxides (NOx: NO, NO 2 , N 2 O), and carbon oxides (COx: CO, CO 2 ).
- PM particulate matter
- HC hydrocarbons
- SOx sulfur oxides
- SO 2 sulfur oxides
- NOx NO, NO 2 , N 2 O
- COx carbon oxides
- Recent emission standards are very strict because of various environmental issues such as global warming, and therefore establishment of technologies for exhaust gas purification is required. Particularly in transportations like automobile, there are many constraints such as size, weight, cost, efficiency and ease of maintenance, but a demand for such technologies is expected to increase rapidly in the future. Therefore, development of an exhaust gas treatment system with high efficiency is an urgent need.
- a catalytic converter with a catalyst such as platinum is commonly used to reduce the amount of PM, HC and NOx in exhaust gas by means of oxidizing and reducing reactions.
- the engines are generally controlled so as to operate on a stoichiometric air fuel ratio by using oxygen sensors.
- emission of COx such as CO 2 is 20% to 30% less than that of the gasoline engines, but reducing catalysts are difficult to be used in diesel engines because of the presence of excess oxygen in exhaust gas. Therefore, various methods for reducing NOx emission are used practically.
- One of the methods is recirculating a part of exhaust gas back to engine cylinders (an exhaust gas recirculation: EGR) and then using a diesel particulate filter (DPF) to collect PM generated in large amounts due to the EGR.
- Other methods include injecting urea into exhaust gas (a urea selective catalytic reduction: urea SCR), and storing NOx temporarily and then reducing the stored NOx at a proper timing by injection of fuel (a diesel particulate-NOx reduction system: DPNR).
- the combination of EGR and DPF not only reduce NOx emission insufficiently, but also adversely affects the drivability and performance of the automobiles.
- the urea SCR requires installation of an additional urea tank and periodic replenishment of urea
- the DPNR requires periodic injection of extra fuel, thereby lowering fuel economy
- implementation of the above methods need to be controlled precisely depending on combustion condition of the engine, and therefore engine control becomes complex.
- Such complex engine control results in enlargement of engine development and period thereof, thereby increasing a cost of the engine development.
- any of the methods needs a precious metal catalyst such as platinum, which is not preferable from the viewpoint of cost and procurement of catalyst material.
- exhaust gas is introduced through an exhaust pipe into a dissociation cylinder (reformer) having corona discharge needles at the outer surface thereof.
- NOx in the exhaust gas is decomposed into oxygen atom (oxygen radical) and nitrogen atom (nitrogen radical) by the discharge in the dissociation cylinder.
- the oxygen atom is reacted with carbon monoxide contained in large amounts in the exhaust gas to produce carbon dioxide, and the nitrogen atom is reacted with the other nitrogen atom to produce nitrogen (N 2 ).
- N 2 nitrogen
- NOx concentration in the exhaust gas is low, and therefore discharge decomposition of low concentrated NOx in the exhaust gas is not efficient.
- the present invention is directed to an exhaust gas treatment system that reduces the amount of NOx in exhaust gas more efficiently.
- an exhaust gas treatment system for an internal combustion engine reduces the amount of NOx in exhaust gas flowing through an exhaust passage of the engine.
- the system has a plasma generator including two electrodes spaced away from each other in the exhaust passage, a high-frequency power supply connected to one of the electrodes, and a NOx absorber provided between the electrodes.
- FIG. 1 is a schematic view of a diesel engine having an exhaust gas treatment system according to a first embodiment of the present invention.
- FIG. 2 is a schematic view of a diesel engine having an exhaust gas treatment system according to a second embodiment of the present invention.
- a diesel engine 1 includes a cylinder block 2 , an intake manifold 3 and an exhaust manifold 4 .
- the cylinder block 2 is formed with four combustion chambers 2 A, 2 B, 2 C and 2 D defined in respective cylinders (not shown in the drawings).
- the intake manifold 3 introduces air from an intake pipe 5 into the combustion chambers 2 A to 2 D, and the exhaust manifold 4 collects exhaust gas from the combustion chambers 2 A to 2 D into an exhaust pipe 6 .
- the exhaust pipe 6 as an exhaust passage, two plasma generators 12 and 22 are disposed in series.
- the diesel engine 1 further includes an electronic control unit (ECU) 10 as a controller.
- ECU electronice control unit
- the plasma generator 12 includes a high-frequency power supply 16 electrically connected to the ECU 10 , two plate-shaped electrodes 13 and 14 spaced away from each other in the exhaust pipe 6 , and a NOx absorber 15 provided between the electrodes 13 and 14 .
- the electrodes 13 and 14 are disposed parallel to each other.
- the electrode 13 is electrically connected to the high-frequency power supply 16 , and the electrode 14 is grounded.
- the electrodes 13 and 14 are covered with a dielectric material.
- the NOx absorber 15 is of a porous body made of electrically conductive Al 2 O 3 and supporting NOx-storage particles made of BaO.
- the plasma generator 22 includes two electrodes 23 and 24 , a high-frequency power supply 26 , and a NOx absorber 25 provided between the electrodes 23 and 24 .
- the exhaust gas then flows in the exhaust pipe 6 and passes through the NOx absorber 15 of the plasma generator 12 , so that NOx in the exhaust gas is stored on the NOx-storage particles of the NOx absorber 15 .
- the plasma generator 12 thus reduces NOx concentration of the exhaust gas passing therethrough.
- the plasma generator 12 cannot reduce the NOx concentration of the exhaust gas any more.
- the exhaust gas passes through the NOx absorber 25 of the other plasma generator 22 , so that NOx in the exhaust gas is stored on the NOx-storage particles of the NOx absorber 25 .
- the plasma generator 22 thus reduces NOx concentration of the exhaust gas passing therethrough, as with the plasma generator 12 .
- the ECU 10 drives the high-frequency power supply 16 so that discharge occurs (that is, plasma is generated) between the electrodes 13 and 14 .
- the discharge energy is set in a range of 642 to 942 kJ/mol. This energy range is higher than a range wherein NOx can be decomposed into nitrogen and oxygen atoms (N, O), but lower than a range wherein nitrogen (N 2 ) can be decomposed into nitrogen atoms. Therefore, NOx on the NOx absorber 15 is decomposed into N 2 and O 2 at a given rate, thereby being released from the NOx absorber 15 .
- NOx is newly produced from the nitrogen and oxygen atoms
- the NOx is stored on the NOx absorbers 15 or 25 again, and finally all NOx on the NOx absorber 15 is decomposed. Since the above discharge energy is lower than the energy for decomposition of N 2 , the newly produced N 2 is prevented from being decomposed to produce NOx again. While the discharge occurs in the plasma generator 12 , the plasma generator 22 stores NOx in the exhaust gas on the NOx absorber 25 .
- the amount of NOx on the NOx absorber 25 of the plasma generator 22 reaches a predetermined limit
- the previously stored NOx on the NOx absorber 15 of the plasma generator 12 is decomposed into N 2 and O 2 by the discharge between the electrodes 13 and 14 to be released from the NOx absorber 15 . Therefore, exhaust gas passing through the NOx absorber 15 , NOx in the exhaust gas is stored on the NOx-storage particles of the NOx absorber 15 again.
- the NOx is stored on the NOx absorber 15 , plasma is generated between the electrodes 23 and 24 in the plasma generator 22 , as in the case of the plasma generator 12 .
- the NOx on the NOx absorber 25 is decomposed into N 2 and O 2 : to be released from the NOx absorber 25 .
- the plasma is generated alternately by the plasma generators 12 and 22 , but may be generated intermittently at a predetermined time interval by each plasma generator. Alternatively, the plasma may be generated by each plasma generator at any time depending on the exhaust gas amount determined by the ECU 10 , based on the engine operating condition such as engine speed.
- the exhaust gas treatment system has two plasma generators 12 and 22 .
- the plasma generator 12 has the electrodes 13 and 14 spaced in the exhaust pipe 6 , the high-frequency power supply 16 connected to the electrode 13 , and the NOx absorber 15 provided between the electrodes 13 and 14 .
- the plasma generator 22 which is of substantially the same structure as the plasma generator 12 is provided in series with the plasma generator 12 in the exhaust pipe 6 . Therefore, while NOx is newly being stored and concentrated on a NOx absorber in one of the two plasma generators, concentrated NOx on a NOx absorber can be decomposed by the plasma between the two electrodes in the other of the two plasma generators. As a result, the amount of NOx in exhaust gas is reduced more efficiently.
- plasma decomposition of highly concentrated NOx on a NOx absorber reduces the amount of NOx in exhaust gas more efficiently, as compared to plasma decomposition of low concentrated NOx in exhaust gas without using a NOx absorber.
- the discharge energy is set in the range of 642 to 942 kJ/mol for each plasma generator, but not limited to this range. If the discharge energy is higher than 942 kJ/mol, N 2 produced from NOx on a NOx absorber may be decomposed to produce NOx again. However, since N 2 is decomposed within a NOx absorber, NOx newly produced from the N 2 is stored on the NOx-storage particles of the NOx absorber again without being released from the NOx absorber. Accordingly, the discharge energy may be set at least in a range of 642 kJ/mol or more.
- the NOx absorber 15 is of a porous body made of electrically conductive Al 2 O 3 and supporting the NOx-storage particles made of BaO, but the present invention is not limited to this structure.
- the NOx absorber 15 may contain at least a material that allows physisorption of NOx thereon.
- the material includes, for example, alkali metals such as Na, K, Li, alkali earth metals such as Ba, Mg, Ca, lanthanoids such as La, Ce, and oxides of the alkali metals, the alkali earth metals or the lanthanoids such as MgO.
- the material further includes, for example, compounds of either the alkali metals, the alkali earth metals or the lanthanoids with elements other than the alkali metals, the alkali earth metals and the lanthanoids such as NaCl, and oxides of the compounds such as BaSO 4 .
- the second embodiment of the present invention differs from the first embodiment in that the number of plasma generators is increased, but the other components and structures are substantially the same as those of the first embodiment. Therefore, the following description will use same reference numbers for the common elements or components in both embodiments, and the description of such elements or components for the second embodiment will be omitted.
- FIG. 2 shows a diesel engine 31 having an exhaust gas treatment system according to the second embodiment.
- the system has the two plasma generators 12 and 22 of the first embodiment and further four plasma generators 32 , 42 , 52 and 62 .
- the six plasma generators 12 , 22 , 32 , 42 , 52 and 62 are provided in series in the exhaust pipe 6 and electrically connected to the ECU 10 .
- the plasma generator 32 includes two electrodes 33 and 34 , a NOx absorber 35 provided between the electrodes 33 and 34 , and a high-frequency power supply 36 .
- the plasma generator 42 includes two electrodes 43 and 44 , a NOx absorber 45 and a high-frequency power supply 46 .
- the plasma generator 52 includes two electrodes 53 and 54 , a NOx absorber 55 and a high-frequency power supply 56 .
- the plasma generator 62 includes two electrodes 63 and 64 , a NOx absorber 65 and a high-frequency power supply 66 .
- the ECU 10 monitors the operating condition (e.g. engine load) of the diesel engine 31 .
- the ECU 10 drives the high-frequency power supplies 16 and 26 alternately, as described with reference to the first embodiment. Therefore, while NOx is newly stored and concentrated on a NOx absorber in one of the two plasma generators, concentrated NOx on a NOx absorber in the other of the two plasma generators is decomposed by the plasma between the two electrodes. As a result, the amount of NOx in exhaust gas is reduced efficiently.
- the ECU 10 drives alternately the four power supplies 16 , 26 , 36 and 46 .
- the ECU 10 drives alternately the six power supplies 16 , 26 , 36 , 46 , 56 and 66 . Since the amount of NOx in exhaust gas is increased with an increase in the engine load of the diesel engine 31 , the number of plasma generators to be operated is increased in the second embodiment. That is, in the second embodiment, the number of plasma generators to be operated is changed depending on the varying engine load of the diesel engine 31 . As a result, the plural plasma generators are operated property depending on the variation in the amount of NOx in exhaust gas, and the amount of NOx in exhaust gas is reduced more efficiently.
- operation timing of each power supply is not described specifically, but any one or more of the power supplies may be operated at a different timing from the other power supplies.
- the power supplies 16 , 26 , 36 , 46 , 56 and 66 may be operated one by one in this order.
- the power supplies 16 , 36 (and 56 ) may be operated concurrently, while the power supplies 26 , 46 (and 66 ) may be operated concurrently.
- the exhaust gas treatment system has a plurality of plasma generators, but may have only one plasma generator. If the system has only one plasma generator 12 , the amount of NOx in exhaust gas cannot be reduced during the plasma decomposition of NOx on the NOx absorber 15 , but highly concentrated NOx on the NOx absorber 15 is decomposed surely. Therefore, the amount of NOx in exhaust gas is reduced more efficiently, as compared to the case of discharge decomposition of low concentrated NOx in exhaust gas.
- the exhaust gas treatment system is used for the diesel engine, but may be used for boilers or other internal combustion engines such as a gasoline engine.
Abstract
An exhaust gas treatment system for an internal combustion engine reduces the amount of NOx in exhaust gas flowing through an exhaust passage of the engine. The system has a plasma generator including two electrodes spaced away from each other in the exhaust passage, a high-frequency power supply connected to one of the electrodes, and a NOx absorber provided between the electrodes.
Description
- The present invention relates to an exhaust gas treatment system for an internal combustion engine.
- In boilers and internal combustion engines, exhaust gas is produced as a result of the combustion of fuel and discharged into the atmosphere. The exhaust gas contains various substances such as particulate matter (PM) including carbide particles, hydrocarbons (HC), sulfur oxides (SOx: SO, SO2), nitrogen oxides (NOx: NO, NO2, N2O), and carbon oxides (COx: CO, CO2). Recent emission standards are very strict because of various environmental issues such as global warming, and therefore establishment of technologies for exhaust gas purification is required. Particularly in transportations like automobile, there are many constraints such as size, weight, cost, efficiency and ease of maintenance, but a demand for such technologies is expected to increase rapidly in the future. Therefore, development of an exhaust gas treatment system with high efficiency is an urgent need.
- In automotive gasoline engines, a catalytic converter with a catalyst such as platinum (a three-way catalytic converter) is commonly used to reduce the amount of PM, HC and NOx in exhaust gas by means of oxidizing and reducing reactions. The engines are generally controlled so as to operate on a stoichiometric air fuel ratio by using oxygen sensors. In diesel engines having high fuel economy, emission of COx such as CO2 is 20% to 30% less than that of the gasoline engines, but reducing catalysts are difficult to be used in diesel engines because of the presence of excess oxygen in exhaust gas. Therefore, various methods for reducing NOx emission are used practically. One of the methods is recirculating a part of exhaust gas back to engine cylinders (an exhaust gas recirculation: EGR) and then using a diesel particulate filter (DPF) to collect PM generated in large amounts due to the EGR. Other methods include injecting urea into exhaust gas (a urea selective catalytic reduction: urea SCR), and storing NOx temporarily and then reducing the stored NOx at a proper timing by injection of fuel (a diesel particulate-NOx reduction system: DPNR).
- However, the combination of EGR and DPF not only reduce NOx emission insufficiently, but also adversely affects the drivability and performance of the automobiles. The urea SCR requires installation of an additional urea tank and periodic replenishment of urea, The DPNR requires periodic injection of extra fuel, thereby lowering fuel economy, Furthermore, implementation of the above methods need to be controlled precisely depending on combustion condition of the engine, and therefore engine control becomes complex. Such complex engine control results in enlargement of engine development and period thereof, thereby increasing a cost of the engine development. Furthermore, any of the methods needs a precious metal catalyst such as platinum, which is not preferable from the viewpoint of cost and procurement of catalyst material.
- In a known engine disclosed in Japanese Unexamined Patent Application Publication No. 61-31615, exhaust gas is introduced through an exhaust pipe into a dissociation cylinder (reformer) having corona discharge needles at the outer surface thereof. NOx in the exhaust gas is decomposed into oxygen atom (oxygen radical) and nitrogen atom (nitrogen radical) by the discharge in the dissociation cylinder. The oxygen atom is reacted with carbon monoxide contained in large amounts in the exhaust gas to produce carbon dioxide, and the nitrogen atom is reacted with the other nitrogen atom to produce nitrogen (N2). As a result, the amount of NOx in the exhaust gas is reduced.
- However, NOx concentration in the exhaust gas is low, and therefore discharge decomposition of low concentrated NOx in the exhaust gas is not efficient.
- The present invention is directed to an exhaust gas treatment system that reduces the amount of NOx in exhaust gas more efficiently.
- In accordance with an aspect of the present invention, an exhaust gas treatment system for an internal combustion engine reduces the amount of NOx in exhaust gas flowing through an exhaust passage of the engine. The system has a plasma generator including two electrodes spaced away from each other in the exhaust passage, a high-frequency power supply connected to one of the electrodes, and a NOx absorber provided between the electrodes.
- Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.
- The features of the present invention that are believed to be novel are set forth with particularity in the appended claims. The invention together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred-embodiments together with the accompanying drawings in which:
-
FIG. 1 is a schematic view of a diesel engine having an exhaust gas treatment system according to a first embodiment of the present invention; and -
FIG. 2 is a schematic view of a diesel engine having an exhaust gas treatment system according to a second embodiment of the present invention. - The following will describe the first embodiment of the present invention with reference to
FIG. 1 . Adiesel engine 1 includes a cylinder block 2, anintake manifold 3 and anexhaust manifold 4. The cylinder block 2 is formed with fourcombustion chambers intake manifold 3 introduces air from anintake pipe 5 into thecombustion chambers 2A to 2D, and theexhaust manifold 4 collects exhaust gas from thecombustion chambers 2A to 2D into anexhaust pipe 6. In theexhaust pipe 6 as an exhaust passage, twoplasma generators diesel engine 1 further includes an electronic control unit (ECU) 10 as a controller. - The
plasma generator 12 includes a high-frequency power supply 16 electrically connected to theECU 10, two plate-shaped electrodes exhaust pipe 6, and a NOx absorber 15 provided between theelectrodes electrodes electrode 13 is electrically connected to the high-frequency power supply 16, and theelectrode 14 is grounded. Theelectrodes plasma generator 12, theplasma generator 22 includes twoelectrodes frequency power supply 26, and a NOx absorber 25 provided between theelectrodes - The following will describe the operation of the exhaust gas treatment system according to the first embodiment, When the
diesel engine 1 is started, air in theintake pipe 5 is introduced through theintake manifold 3 into thecombustion chambers 2A to 2D, and compressed by pistons (not shown in the drawings). Diesel fuel injected from injection nozzles (not shown in the drawings) into the compressed air is ignited spontaneously for combustion, and exhaust gas is discharged from thecombustion chambers 2A to 2D into theexhaust manifold 4. - The exhaust gas then flows in the
exhaust pipe 6 and passes through the NOx absorber 15 of theplasma generator 12, so that NOx in the exhaust gas is stored on the NOx-storage particles of the NOx absorber 15. Theplasma generator 12 thus reduces NOx concentration of the exhaust gas passing therethrough. When the amount of NOx on the NOx absorber 15 reaches a predetermined limit, theplasma generator 12 cannot reduce the NOx concentration of the exhaust gas any more. In such a case, the exhaust gas passes through the NOx absorber 25 of theother plasma generator 22, so that NOx in the exhaust gas is stored on the NOx-storage particles of the NOx absorber 25. Theplasma generator 22 thus reduces NOx concentration of the exhaust gas passing therethrough, as with theplasma generator 12. - When the amount of NOx on the NOx absorber 15 reaches a predetermined level, the
ECU 10 drives the high-frequency power supply 16 so that discharge occurs (that is, plasma is generated) between theelectrodes plasma generator 12, theplasma generator 22 stores NOx in the exhaust gas on the NOx absorber 25. - In the meantime, the amount of NOx on the NOx absorber 25 of the
plasma generator 22 reaches a predetermined limit, However, the previously stored NOx on the NOx absorber 15 of theplasma generator 12 is decomposed into N2 and O2 by the discharge between theelectrodes electrodes plasma generator 22, as in the case of theplasma generator 12. As a result, the NOx on the NOx absorber 25 is decomposed into N2 and O2: to be released from the NOx absorber 25. - The above-described operations of the
plasma generators plasma generators ECU 10, based on the engine operating condition such as engine speed. - The exhaust gas treatment system according to the first embodiment has two
plasma generators plasma generator 12 has theelectrodes exhaust pipe 6, the high-frequency power supply 16 connected to theelectrode 13, and theNOx absorber 15 provided between theelectrodes plasma generator 22 which is of substantially the same structure as theplasma generator 12 is provided in series with theplasma generator 12 in theexhaust pipe 6. Therefore, while NOx is newly being stored and concentrated on a NOx absorber in one of the two plasma generators, concentrated NOx on a NOx absorber can be decomposed by the plasma between the two electrodes in the other of the two plasma generators. As a result, the amount of NOx in exhaust gas is reduced more efficiently. In addition, plasma decomposition of highly concentrated NOx on a NOx absorber reduces the amount of NOx in exhaust gas more efficiently, as compared to plasma decomposition of low concentrated NOx in exhaust gas without using a NOx absorber. - Though two plasma generators are provided in the exhaust pipe in the first embodiment, three or more plasma generators may be used to achieve the same effect. In the first embodiment, the discharge energy is set in the range of 642 to 942 kJ/mol for each plasma generator, but not limited to this range. If the discharge energy is higher than 942 kJ/mol, N2 produced from NOx on a NOx absorber may be decomposed to produce NOx again. However, since N2 is decomposed within a NOx absorber, NOx newly produced from the N2 is stored on the NOx-storage particles of the NOx absorber again without being released from the NOx absorber. Accordingly, the discharge energy may be set at least in a range of 642 kJ/mol or more.
- In the first embodiment, the
NOx absorber 15 is of a porous body made of electrically conductive Al2O3 and supporting the NOx-storage particles made of BaO, but the present invention is not limited to this structure. According to the invention, theNOx absorber 15 may contain at least a material that allows physisorption of NOx thereon. The material includes, for example, alkali metals such as Na, K, Li, alkali earth metals such as Ba, Mg, Ca, lanthanoids such as La, Ce, and oxides of the alkali metals, the alkali earth metals or the lanthanoids such as MgO. The material further includes, for example, compounds of either the alkali metals, the alkali earth metals or the lanthanoids with elements other than the alkali metals, the alkali earth metals and the lanthanoids such as NaCl, and oxides of the compounds such as BaSO4. - The following will describe the second embodiment of the present invention with reference to
FIG. 2 . The second embodiment differs from the first embodiment in that the number of plasma generators is increased, but the other components and structures are substantially the same as those of the first embodiment. Therefore, the following description will use same reference numbers for the common elements or components in both embodiments, and the description of such elements or components for the second embodiment will be omitted. -
FIG. 2 shows adiesel engine 31 having an exhaust gas treatment system according to the second embodiment. The system has the twoplasma generators plasma generators plasma generators exhaust pipe 6 and electrically connected to theECU 10. As with theplasma generators plasma generator 32 includes twoelectrodes NOx absorber 35 provided between theelectrodes frequency power supply 36. Similarly, theplasma generator 42 includes twoelectrodes NOx absorber 45 and a high-frequency power supply 46. Theplasma generator 52 includes twoelectrodes frequency power supply 56. Theplasma generator 62 includes twoelectrodes 63 and 64, aNOx absorber 65 and a high-frequency power supply 66. - The following will describe the operation of the exhaust gas treatment system according to the second embodiment. While the
diesel engine 31 is in operation, theECU 10 monitors the operating condition (e.g. engine load) of thediesel engine 31. When theECU 10 detects that thediesel engine 31 is operating under low engine load, theECU 10 drives the high-frequency power supplies - When the engine load is increased, the
ECU 10 drives alternately the fourpower supplies ECU 10 drives alternately the sixpower supplies diesel engine 31, the number of plasma generators to be operated is increased in the second embodiment. That is, in the second embodiment, the number of plasma generators to be operated is changed depending on the varying engine load of thediesel engine 31. As a result, the plural plasma generators are operated property depending on the variation in the amount of NOx in exhaust gas, and the amount of NOx in exhaust gas is reduced more efficiently. - In the second embodiment, operation timing of each power supply is not described specifically, but any one or more of the power supplies may be operated at a different timing from the other power supplies. For example, the power supplies 16, 26, 36, 46, 56 and 66 may be operated one by one in this order. For example, the power supplies 16, 36 (and 56) may be operated concurrently, while the power supplies 26, 46 (and 66) may be operated concurrently.
- In the first and second embodiments, the exhaust gas treatment system has a plurality of plasma generators, but may have only one plasma generator. If the system has only one
plasma generator 12, the amount of NOx in exhaust gas cannot be reduced during the plasma decomposition of NOx on theNOx absorber 15, but highly concentrated NOx on theNOx absorber 15 is decomposed surely. Therefore, the amount of NOx in exhaust gas is reduced more efficiently, as compared to the case of discharge decomposition of low concentrated NOx in exhaust gas. - In the first and second embodiments, the exhaust gas treatment system is used for the diesel engine, but may be used for boilers or other internal combustion engines such as a gasoline engine.
- Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein but may be modified within the scope of the appended claims.
Claims (6)
1. An exhaust gas treatment system for an internal combustion engine, the system for reducing the amount of NOx in exhaust gas flowing through an exhaust passage of the engine, comprising:
a plasma generator including;
two electrodes spaced away from each other in the exhaust passage;
a high-frequency power supply connected to one of the electrodes; and
a NOx absorber provided between the electrodes.
2. The exhaust gas treatment system according to claim 1 , wherein a plurality of plasma generators is provided in series in the exhaust passage, and the plasma generators are operated at different timings from each other.
3. The exhaust gas treatment system according to claim 2 , further comprising a controller that monitors engine load and changes the number of plasma generators to be operated depending on the engine load.
4. The exhaust gas treatment system according to claim 1 , wherein the energy for discharge between the electrodes is set in a range of 642 to 942 kJ/mol.
5. The exhaust gas treatment system according to claim 1 , wherein the NOx absorber contains a material that allows physisorprtion of NOx thereon.
6. The exhaust gas treatment system according to claim 5 , wherein the material is selected from the group consisting of:
alkali metals;
alkali earth metals;
lanthanoids;
oxides of the alkali metals, the alkali earth metals or the lanthanoids;
compounds of either the alkali metals, the alkali earth metals or the lanthanoids with elements other than the alkali metals, the alkali earth metals and the lanthanoids; and
oxides of the compounds.
Applications Claiming Priority (2)
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JP2007-339322 | 2007-12-28 | ||
JP2007339322A JP4941284B2 (en) | 2007-12-28 | 2007-12-28 | Exhaust gas treatment system for internal combustion engine |
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US20090211231A1 true US20090211231A1 (en) | 2009-08-27 |
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US12/342,412 Abandoned US20090211231A1 (en) | 2007-12-28 | 2008-12-23 | Exhaust gas treatment system for an internal combustion engine |
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US (1) | US20090211231A1 (en) |
EP (1) | EP2075423A1 (en) |
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US20100242438A1 (en) * | 2009-03-26 | 2010-09-30 | Gm Global Technology Operations, Inc. | Exhaust gas treatment system including a four-way catalyst and urea scr catalyst and method of using the same |
US20100242448A1 (en) * | 2009-03-26 | 2010-09-30 | Gm Global Technology Operations, Inc. | Exhaust gas treatment system including a four-way catalyst and urea scr catalyst and method of using the same |
US8883103B1 (en) * | 2014-01-16 | 2014-11-11 | Denso International America, Inc. | Catalytic converter for treating ionized exhaust |
CN106422690A (en) * | 2016-08-25 | 2017-02-22 | 北京航天环境工程有限公司 | Organic waste gas plasma processing device |
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Families Citing this family (3)
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---|---|---|---|---|
JP5356183B2 (en) * | 2009-11-04 | 2013-12-04 | 株式会社 Acr | Plasma reactor and exhaust gas purification apparatus using the same |
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Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6038853A (en) * | 1996-08-19 | 2000-03-21 | The Regents Of The University Of California | Plasma-assisted catalytic storage reduction system |
US6038854A (en) * | 1996-08-19 | 2000-03-21 | The Regents Of The University Of California | Plasma regenerated particulate trap and NOx reduction system |
US6238525B1 (en) * | 1998-04-30 | 2001-05-29 | Degussa-Hüls Aktiengesellschaft | Process for reducing the nitrogen oxides content of exhaust gas from an internal combustion engine |
US20040234430A1 (en) * | 2003-05-20 | 2004-11-25 | Toyota Jidosha Kabushiki Kaisha | Exhaust gas purifying apparatus and method of using the same |
US20040231321A1 (en) * | 2003-05-20 | 2004-11-25 | Toyota Jidosha Kabushiki Kaisha | Exhaust gas purifying apparatus and method of using the same |
US20050284137A1 (en) * | 2004-05-07 | 2005-12-29 | Neophotech, Inc. | Method for processing combustion exhaust gas containing soot particles and NOx |
US20060005531A1 (en) * | 2002-08-30 | 2006-01-12 | Sabine Calvo | System for exhaust gas treatment comprising a gas ionizing system with ionized air injection |
US20060048506A1 (en) * | 2004-09-07 | 2006-03-09 | Neophotech, Inc. | System for processing combustion exhaust gas containing soot particles and NOx |
US20060087243A1 (en) * | 2004-09-03 | 2006-04-27 | Rijing Zhan | Packed-bed radial-flow non-thermal plasma reactor |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS6131615A (en) | 1984-07-25 | 1986-02-14 | Niles Parts Co Ltd | Engine exhaust gas purifier for removing nitrogen oxides |
JP3089213B2 (en) * | 1996-07-25 | 2000-09-18 | 三菱重工業株式会社 | Multistage exhaust gas treatment reactor |
US5746984A (en) * | 1996-06-28 | 1998-05-05 | Low Emissions Technologies Research And Development Partnership | Exhaust system with emissions storage device and plasma reactor |
JP2001182525A (en) * | 1999-12-22 | 2001-07-06 | Toyota Central Res & Dev Lab Inc | Nox purifying method under plasma and device thereof |
JP2001300257A (en) * | 2000-04-26 | 2001-10-30 | Mitsubishi Heavy Ind Ltd | Treatment device and decomposing method of waste gas by plasma decomposition process |
JP2002155731A (en) * | 2000-11-21 | 2002-05-31 | Toyota Motor Corp | Exhaust emission control device of internal combustion engine |
JP4828056B2 (en) * | 2001-09-10 | 2011-11-30 | 三菱重工メカトロシステムズ株式会社 | Reduction device and denitration device |
JP2006261040A (en) * | 2005-03-18 | 2006-09-28 | Ngk Insulators Ltd | Plasma reactor |
JP4718344B2 (en) * | 2006-02-22 | 2011-07-06 | 三菱電機株式会社 | Air purification apparatus and air purification method using the same |
JP4751264B2 (en) * | 2006-07-31 | 2011-08-17 | 株式会社東芝 | Ventilation gas purification device and purification method thereof |
-
2007
- 2007-12-28 JP JP2007339322A patent/JP4941284B2/en not_active Expired - Fee Related
-
2008
- 2008-12-23 EP EP08172767A patent/EP2075423A1/en not_active Withdrawn
- 2008-12-23 US US12/342,412 patent/US20090211231A1/en not_active Abandoned
Patent Citations (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6038853A (en) * | 1996-08-19 | 2000-03-21 | The Regents Of The University Of California | Plasma-assisted catalytic storage reduction system |
US6038854A (en) * | 1996-08-19 | 2000-03-21 | The Regents Of The University Of California | Plasma regenerated particulate trap and NOx reduction system |
US6374595B1 (en) * | 1996-08-19 | 2002-04-23 | The Regents Of The University Of California | Plasma-assisted catalytic storage reduction system |
US6238525B1 (en) * | 1998-04-30 | 2001-05-29 | Degussa-Hüls Aktiengesellschaft | Process for reducing the nitrogen oxides content of exhaust gas from an internal combustion engine |
US20060005531A1 (en) * | 2002-08-30 | 2006-01-12 | Sabine Calvo | System for exhaust gas treatment comprising a gas ionizing system with ionized air injection |
US20040234430A1 (en) * | 2003-05-20 | 2004-11-25 | Toyota Jidosha Kabushiki Kaisha | Exhaust gas purifying apparatus and method of using the same |
US20040231321A1 (en) * | 2003-05-20 | 2004-11-25 | Toyota Jidosha Kabushiki Kaisha | Exhaust gas purifying apparatus and method of using the same |
US20050284137A1 (en) * | 2004-05-07 | 2005-12-29 | Neophotech, Inc. | Method for processing combustion exhaust gas containing soot particles and NOx |
US20060087243A1 (en) * | 2004-09-03 | 2006-04-27 | Rijing Zhan | Packed-bed radial-flow non-thermal plasma reactor |
US20060048506A1 (en) * | 2004-09-07 | 2006-03-09 | Neophotech, Inc. | System for processing combustion exhaust gas containing soot particles and NOx |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20100242438A1 (en) * | 2009-03-26 | 2010-09-30 | Gm Global Technology Operations, Inc. | Exhaust gas treatment system including a four-way catalyst and urea scr catalyst and method of using the same |
US20100242448A1 (en) * | 2009-03-26 | 2010-09-30 | Gm Global Technology Operations, Inc. | Exhaust gas treatment system including a four-way catalyst and urea scr catalyst and method of using the same |
US8505279B2 (en) * | 2009-03-26 | 2013-08-13 | GM Global Technology Operations LLC | Exhaust gas treatment system including a four-way catalyst and urea SCR catalyst and method of using the same |
US8555617B2 (en) | 2009-03-26 | 2013-10-15 | GM Global Technology Operations LLC | Exhaust gas treatment system including a four-way catalyst and urea SCR catalyst and method of using the same |
US8883103B1 (en) * | 2014-01-16 | 2014-11-11 | Denso International America, Inc. | Catalytic converter for treating ionized exhaust |
CN106422690A (en) * | 2016-08-25 | 2017-02-22 | 北京航天环境工程有限公司 | Organic waste gas plasma processing device |
RU2689020C1 (en) * | 2018-10-30 | 2019-05-23 | Радченко Виталий Анатольевич | Device for the internal combustion engines emissions cleaning of the nitrogen oxides using the non-equilibrium low-temperature plasma and the absorber |
WO2020091624A1 (en) * | 2018-10-30 | 2020-05-07 | РАДЧЕНКО, Виталий Анатольевич | Device for plasma cleaning engine emissions of nitrogen oxides |
Also Published As
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JP4941284B2 (en) | 2012-05-30 |
JP2009162059A (en) | 2009-07-23 |
EP2075423A1 (en) | 2009-07-01 |
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