Arrangement and procedure for the treatment of exhaust gases from a single-combustion engine

专利摘要:
Summary The present invention relates to an arrangement and a method for treating exhaust gases from an internal combustion engine (2). The arrangement comprises an exhaust line (3) which discharges the exhaust gases from the internal combustion engine (2), a turbine (4, 12, 27) with which energy is extracted from the exhaust gases in the exhaust line (3), a bypass line (14) comprising an inlet (14a) where exhaust gases are received from the exhaust line (3) in a position upstream of the turbine (4, 12, 27) and an outlet (14b) where exhaust gases are led back to the exhaust line (3) in a position downstream of the turbine (4, 12, 27). A first oxidation catalyst (15) is arranged in the bypass line (14) and a second oxidation ion catalyst (19) is arranged in the exhaust line (3) in a position downstream of the bypass line outlet (14b). The arrangement comprises control means (11, 13, 16, 17) which are adapted to regulate the flow and temperature of the exhaust gases passed through the first oxidation catalyst (15) in the bypass line (14) so that the first oxidation catalyst (15) and the second oxidation catalyst (19) together provide an oxidation of nitric oxide (NO) to nitrogen dioxide (NO2) in an amount such that the exhaust gases leaving the second oxidation catalyst (19) have a desired separation of nitric oxide (NO) and nitrogen dioxide (NO2).
公开号:SE1251092A1
申请号:SE1251092
申请日:2012-09-27
公开日:2014-03-28
发明作者:Håkan Sarby
申请人:Scania Cv Ab；
IPC主号:

专利说明:

BACKGROUND OF THE INVENTION AND PRIOR ART The invention relates to an arrangement and method for treating exhaust gases from an internal combustion engine according to the preambles of claims 1 and 11.
To reduce emissions of nitrogen oxides NO frail internal combustion engines are used bi.a. a teluiik called SCR (Selective Catalytic Reduction). This technology involved a solution of urea supplied in a certain dose to the exhaust gases in an exhaust line. Urea release can be sprayed into the exhaust line, after which the finely divided urea solution evaporates in contact with the hot exhaust gases so that ammonia is formed. The mixture of ammonia and exhaust gases is then passed through an SCR catalyst. The nitrogen of the nitrogen oxides In the exhaust gases, the nitrogen in the ammonia reacts so that nitrogen gas is formed. The oxygen of the nitrogen oxides reacts with the choice in the ammonia sh that water is formed. The nitrogen oxides in the exhaust gases are thus reduced in the catalyst to nitrogen gas and water vapor. With the correct dosage of urea, the emissions of nitrogen oxides from the internal combustion engine can be greatly reduced.
Nitrogen oxides NOxi exhaust gases consist of nitrogen monoxide NO and nitrogen dioxide NO2. The ability of SCR catalysts to reduce the amount of nitrogen oxides in exhaust gases is optimal as the exhaust gases contain the same amount of nitrogen monoxide and nitrogen dioxide. The proportion of nitrogen dioxide must thus be 50%. Exhaust gases from diesel engines in particular usually contain a much lower proportion of nitrogen dioxide and nitrogen monoxide. In order to increase the proportion of nitrogen dioxide, it is advisable to arrange an oxidation catalyst DOC (Diesel Oxidation Catalyst) in the exhaust line in a position upstream of the SCR catalyst. An oxidation catalyst oxidizes nitrogen monoxide NO to nitrogen dioxide NO2. Thus, the proportion of nitrogen dioxide NO2 in the exhaust gases can increase to the level at which the SCR catalyst provides an optimal capacity to reduce nitrogen oxides NOx. 2 The shape of an oxidation catalyst oxidizing nitrogen monoxide NO to nitrogen dioxide NO2 varies with the temperature and flow of the exhaust gases. Because the temperature and flow of exhaust gases vary during operation of a combustion engine, an oxidation catalyst may not always deliver the desired distribution between the two kinds of nitric oxide. If an oxidation catalyst is dimensioned to oxidize nitrogen oxides in exhaust gases at an average temperature of the exhaust gases, a too low proportion of nitrogen dioxide NO2 is obtained at low exhaust temperatures and a too high proportion of nitrogen dioxide NO2 at high exhaust temperatures. A too low proportion of nitrogen dioxide NO2 results in a poor efficiency in SCR catalyst. An excessively high proportion of nitrogen dioxide NO2 results in nitrous oxide formed in contact with the injected urea solution. Nitrous oxide is a strong greenhouse gas.
US 7, 810, 316 disclose an exhaust line of an internal combustion engine with exhaust aftertreatment components. In one embodiment, the exhaust line comprises two parallel lines which are each provided with an oxidation catalyst. One oxidation catalyst is mainly used to oxidize nitrogen monoxide to nitrogen dioxide when the combustion engine is loaded and the other oxidation catalyst is mainly used to oxidize nitrogen monoxide to nitrogen dioxide when the combustion engine is heavily loaded. A valve controls the exhaust flow to the respective parallel lines before it is led to an SCR catalyst and / or a particle filter.
SUMMARY OF THE INVENTION The object of the present invention is to provide an arrangement for aftertreatment of exhaust gases from an internal combustion engine where oxidation of nitrogen monoxide to nitrogen dioxide takes place in an amount such that the exhaust gases obtain a desired distribution of nitrogen monoxide and nitrogen dioxide under varying operating conditions.
This object is achieved with arrangements of the kind mentioned in the introduction, which is distinguished by the features stated in the cantilevered part of claim 1. Thus, in this case, a first oxidation catalyst is used which is arranged in a bypass line to the exhaust line and a second oxidation catalyst which is arranged in the exhaust line downstream of the bypass line. The first oxidation catalyst The oxidation capacity depends on the temperature and flow of the exhaust gases through the bypass line. With the aid of said control means, the flow and temperature of the exhaust gases passed through the first oxidation catalyst can be regulated. With knowledge of the oxidation capacity of the second oxidation catalyst, the oxidation capacity of the first oxidation catalyst can be controlled so that the first oxidation catalyst and the second oxidation catalyst together provide an oxidation of nitrogen monoxide to nitrogen dioxide in an amount sh to the exhaust gas which distributes the second catalyst. of kvdvemonoxide and kvdvedioxide. According to the invention, the bypass line extends around a turbine in the exhaust line. This allows exhaust gases to be led to the first oxidation catalyst from a position upstream of the turbine. The exhaust gases have a higher pressure and a higher temperature than the exhaust gases which are led to the second oxidation catalyst which is led by the bellows downstream of the turbine. Furthermore, the first oxidation catalyst can provide a very good supplementary oxidation capacity in the case of operation as the second oxidation catalyst has a relatively small oxidation capacity.
According to a preferred embodiment of the present invention, the second oxidation catalyst is dimensioned so that it itself has the capacity to oxidize nitrogen monoxide to nitrogen dioxide in an amount such that the desired distribution of nitrogen dioxide and nitrogen dioxide is obtained in the exhaust gases which release the second oxidation. there are optimal conditions for oxidizing nitrogen monoxide to nitrogen dioxide. Optimal conditions for oxidizing nitrous oxide to nitrogen dioxide racier ie. a small slide of exhaust gases with a temperature of about 300 ° C is passed through the second oxidation catalyst. At optimal conditions, no exhaust gases are passed through the bypass line and the first oxidation catalyst, but the second oxidation catalyst is responsible for the entire oxidation process. If the temperature of the exhaust gases decreases and / or the exhaust flow increases, the second oxidation catalyst does not increase the longer capacity to oxidize nitrogen monoxide to nitrogen dioxide to an extent that the desired ratio is obtained. In this case, an appropriate amount of exhaust gas is controlled by the first oxidation catalyst so that it provides a supplemental oxidation so that the desired ratio of nitrogen oxide to nitrogen dioxide is obtained downstream of the second oxidation catalyst.
According to a preferred embodiment of the present invention, the first oxidation catalyst has a higher content of a noble metal coating than the second oxidation catalyst. Noble metal coatings of platinum, palladium and radium can be anydridas as catalyst materials in oxidation catalysts. The greater the amount of noble metal per unit area that the oxidation catalyst has, the higher the oxidation capacity. By giving the first oxidation catalyst a high content of, for example, platinum, it can provide a very high oxidation capacity when needed. The second oxidation catalyst can be given a lower oxidation capacity and armed forces with a lower content of platinum.
According to a preferred embodiment of the present invention, said control means comprises at least one valve means in the bypass line and a control unit soul Ar adapted to control the valve means so that the first oxidation catalyst is flowed through by a desired proportion of the exhaust stream in the exhaust line. Alternatively, the valve means may be located at the exhaust line at the inlet or outlet of the bypass line. The valve member advantageously had a design so that it could be stabled in many different layers so that the flow through the bypass line could be regulated stepwise or steplessly.
According to a preferred embodiment of the present invention, said control means alien comprises an exhaust brake arranged in the exhaust line in a position between the inlet and the outlet of the bypass line. The exhaust brake can be an existing exhaust brake in a vehicle. An exhaust brake draws a valve arranged in the exhaust line. In this case, the control unit can regulate the exhaust flow both through the bypass line and through the exhaust line. This gives rise to a number of possibilities for regulating the flocculation and temperature of the exhaust gases which are led through the bypass line and thus the oxidation capacity of the first oxidation catalyst.
According to a preferred embodiment of the present invention, said control means comprises at least one sensor adapted to sense a parameter by which the control unit estimates the flow and the temperature of the exhaust gases passed through the first oxidation catalyst. Said sensor may be one or more mandatory temperature sensors or river sensors. Other types of sensors can of course be used. With knowledge of the flow and temperature of the exhaust gases conducted through the exhaust line, the oxidation capacity of the second oxidation catalyst can be determined. The control unit can then direct a suitable proportion of the exhaust gas flow in the exhaust line through the bypass line and the first oxidation catalyst so that the desired distribution of nitrogen monoxide and nitrogen dioxide is obtained.
According to a preferred embodiment of the present invention, the turbine is a turbine of a turbocharger or a compound turbine. Many vehicles are powered by overcharged internal combustion engines. The turbine can in this case be a component of a turbocharger which also comprises a compressor for compressing air which is led to the free-combustion engine. The bypass line with the first oxidation catalyst can advantageously be arranged in an exhaust line around such a turbine. The bypass line can be made up of an existing wastegate of the turbine. In vehicles where the inlet air is compressed in two stages by a high-pressure turbine and a low-pressure turbine, the bypass line with the first oxidation catalyst can be arranged around one of said turbines. In vehicles with a compound turbine, Liven is given the opportunity to arrange the bypass line with the first oxidation catalyst so that it receives exhaust gases at a high temperature upstream of the compound turbine.
According to a preferred embodiment of the present invention, the arrangement comprises an SCR catalyst anorinated in the exhaust line in a position downstream of the second oxidation catalyst with respect to the intended direction of flow of the exhaust gases in the exhaust line. In an SCR catalyst, the nitrogen oxides in the exhaust gases are reduced to nitrogen gas and water vapor. This reduction takes place more efficiently, ie nitrogen oxidation contains an equal proportion of nitrogen monoxide and nitrogen dioxide. In the exhaust gases that leave an internal combustion engine, the proportion of nitrogen dioxide is clearly lower than the proportion of nitrogen monoxide. With the aid of the first oxidation catalyst and the second oxidation catalyst, the proportion of nitrogen dioxide can be increased at the expense of the proportion of nitrogen monoxide, so that an optimal ratio between nitrogen oxide and nitrogen dioxide can essentially always be achieved under varying operating conditions. The arrangement may in this case comprise components for supplying urea solution in a position upstream of the SCR catalyst with respect to the intended flow direction of the exhaust gases in the exhaust line. A solution of urea is injected into the exhaust line. That is, the urea solution preceded by the hot exhaust gases forms ammonia which is passed together with the exhaust gases through the SCR catalyst. With the correct dosage of urea, the emissions of nitrogen oxides from the internal combustion engine can be reduced to a large extent.
According to a preferred embodiment of the present invention, the arrangement comprises a particle filter arranged in a position downstream of the second oxidation catalyst with respect to the intended flow direction of the exhaust gases in the exhaust line. In a particulate filter, soot particles get stuck and burned in the exhaust gases. The operating temperature of the exhaust gases is not always high enough to continuously maintain a temperature of the particulate filter at which the soot particles are prepared. However, the combustion temperature of the soot particles can be lowered considerably as the exhaust gases contain a high proportion of nitrogen dioxide. To reduce the ignition temperature of the soot particles, an oxidation catalyst can advantageously be used. With an appropriate proportion of nitrogen dioxide in the exhaust gases, an annealing temperature can be obtained at which the soot particles are burned substantially continuously during the varying conditions of an internal combustion engine. If both a particulate filter and an SCR catalyst are used in the exhaust line, the particulate filter is placed between the oxidation catalyst and the SCR catalyst. Another set of MO exhaust gas temperatures is to inject unburned fuel in a position upstream of the first or second oxidation catalyst. Then the temperature of the exhaust gases can be raised markedly in the oxidation catalysts, which guarantees a combustion of the soot particles in the downstream particle filter.
The object mentioned in the introduction is also achieved by the method stated in claim 11.
BRIEF DESCRIPTION OF THE DRAWINGS In the following, an exemplary embodiment of the invention is described with reference to the accompanying drawings, in which: Fig. 1 shows an arrangement for treating exhaust gases from an internal combustion engine according to a first embodiment of the invention, Fig. 2 shows a arrangements for treating exhaust gases from an internal combustion engine according to a second embodiment of the invention and Fig. 3 shows an arrangement for treating exhaust gases from an internal combustion engine according to a third embodiment of the invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION Fig. 1 schematically shows a vehicle 11 driven by an overcharged internal combustion engine 2 which may be a diesel engine. The vehicle may be a heavy vehicle. The exhaust gases from the combustion engine 2 are discharged via an exhaust line 3. The exhaust gases that leave the combustion engine 2 have an overpressure. The overpressure of the exhaust gases is used to drive a turbine 4 of a turbocharger. The turbine 4 drives a compressor 5 of the turbocharger. The grain compressor 5 compresses air which is led into an inlet line 6 for air to the combustion engine 2. The inlet line 6 comprises a charge air cooler 7 where the compressed In is cooled before it is led to the internal combustion engine 2. A return line 8 Recirculation of exhaust gases extends from the exhaust line 3 and to the inlet line 6. The return line 8 comprises an EGR cooler 9 for cooling the recirculating exhaust gases before they are mixed with the compressed tuft and led to the combustion engine 2.
The turbine 4 is equipped with a so-called wastgate which comprises an exhaust passage 10 with a wastegate valve 11 with which part it is possible to lead a part of the exhaust gases past the turbine 4. A wastegate valve 11 is normally opened when the boost pressure of the turbocharger becomes too high. The exhaust line 3 in this case comprises a second turbine in the form of a compound turbine 12 which is located downstream of the turbine of the turbocharger 4. A compound turbine 12 is used to extract energy from the exhaust gases for operation of the vehicle. An exhaust brake 13 arranged in the exhaust line 3 downstream of the compound turbine 12. 13 is a valve in the form of a slit in the exhaust line 3 with which it is possible to substantially steplessly regulate the exhaust flow in the exhaust line 3. The exhaust line 3 is provided with a bypass line 14. The bypass line 14 comprises an inlet 14a where exhaust gases from the exhaust line 3 are received in a position upstream of the compound turbine 12 and the exhaust brake 13. The bypass line 14 includes an outlet 14b where exhaust gases are led back to the exhaust line 3 in a position downstream of the compound turbine 12 and the exhaust brake 13.
The bypass line 14 comprises a first oxidation catalyst 15. An oxidation catalyst has the ability to oxidize nitrogen monoxide NO to nitrogen dioxide NO2. The ability of an oxidation catalyst to oxidize nitrogen monoxide to nitrogen dioxide depends on several parameters. One such parameter is the temperature of the exhaust gases. As the exhaust gases have a higher temperature, a more efficient oxidation is obtained than when the exhaust gases have a lower temperature. An optimum oxidation capacity is obtained at about 300 ° C. Another parameter is the flow of exhaust gases through the oxidation catalyst. With a large exhaust flow, a smaller part of the nitrogen monoxide in the exhaust gases can be oxidized to nitrogen dioxide than with a smaller exhaust Wide. A third parameter is the content of noble metal in the oxidation catalyst. The oxidation catalyst may contain platinum, palladium or rhodium noble metal coatings. A coating with a high content of a noble metal results in a more efficient oxidation process than a coating with a higher content of the noble metal. The bypass line 14 is also provided with a valve means 16. With the nip of the valve means 16, the exhaust flow through the bypass line 14 can be controlled. Thus, only the exhaust gases in the exhaust line 3 which are led into the bypass line 14 pass through the first oxidation catalyst 15.
A control unit 17 adapted to control the wastegate valve 11, the exhaust brake 13 and the yentilator 16. The control unit 17 receives information from a number of sensors 18 which sense parameters with which the temperature and temperature of the exhaust gases can be determined. The sensors 18 can detect the temperature, flow, pressure of the exhaust gases. An ideal number of positions in the exhaust line 3 and the bypass line 14. The control unit 17 can also receive information from sensors 18 which show the content of nitrogen oxide, nitrogen dioxide or nitrous oxide on the suitable positions in the exhaust line 3. The control unit 17 may be a computer unit with software suitable for this purpose. The exhaust line 3 comprises a second oxidation catalyst 19 which is arranged in the exhaust line 3 in a position downstream of the bypass line 14b of the bypass line. All exhaust gases in the exhaust line 3 are passed through the second oxidation catalyst 19.
A particulate filter 20 is arranged downstream of the second oxidation catalyst 19. The task of the particle filter 20 is to capture the soot particles in the exhaust gases. The soot particles are then incinerated in the particulate filter 20. A seal to guarantee a good combustion of the soot particles in the particulate filter is all lead exhaust gases with a high content of nitrogen dioxide through the particulate filter With the aid of the first oxidation catalyst 15 and the second oxidation catalyst 19, the exhaust gases can be supplied with nitrogen dioxide in an amount so that the combustion temperature is lowered to a temperature level maintained in the particulate filter during normal operation of the combustion engine. In this case, the soot particles can be burned substantially continuously in the particle filter. In this case, a device 21 for supplying unburned fuel HC in the bypass line 14 is also arranged in a position upstream of the first oxidation catalyst 15. By injecting unburned fuel in the event of an accident, the exhaust gas temperature can be raised substantially in the first oxidation catalyst 15 and clamped therein. downstream, the particle filter 20 sh arranged that the soot particles were safely burned.
The exhaust line is equipped with an SCR catalyst 23 for catalytic exhaust purification according to the method referred to as SCR (Selective Catalytic Reduction). This method meant that a urea solution was injected into the exhaust gases. Urea discharge can be stored in a tank and is led, via a line, to an injection means 22 which injects the urea discharge into the exhaust line. The control unit 17 or another separate control unit can control the supply of the urea lasing. Such a control unit can, with information regarding specific engine parameters, calculate the amount of urea solution that needs to be added for all the liquid oxide in the exhaust gases to be reduced in an optimal way. The urea solution supplied is heated by the exhaust gases in the exhaust line so that it is evaporated and converted to ammonia. The mixture of ammonia and the exhaust gases is then passed to the SCR catalyst 23. In the SCR-9 catalyst 23, the nitrogen of the nitrogen oxides in the exhaust gases reacts with the nitrogen in the ammonia so that nitrogen gas is formed. The oxygen of the nitrogen oxides reacts with the water in the ammonia to form water. The nitrogen oxides in the exhaust gases are thus reduced in the SCR catalyst 23 to nitrogen gas and water vapor. The nitrogen oxides NOxi exhaust gases consist of nitrogen monoxide NO and nitrogen dioxide NO2. An SCR catalyst 23 reduces the amount of nitrogen oxides in the exhaust gases at an optimal salt as the exhaust gases passed through the SCR catalyst 23 have an equal amount of nitrogen monoxide as nitrogen dioxide. An SCR catalyst thus reduces nitrogen oxides optimally as the proportion of nitrogen dioxide is 50% of the total amount of nitrogen oxides. Exhaust gases from internal combustion engines generally contain a significant stone 10 of nitrogen monoxide and nitrogen dioxide.
Increasing the proportion of nitrogen dioxide in the exhaust gases is thus important both to provide a substantially continuous combustion of the soot particles in the particulate filters 20 and 16r to reduce the nitrogen oxides in the exhaust gases in the SCR catalyst 23. The exhaust line also includes an ammonia catalyst 24 where any excess ammonia and nitrogen dioxide is converted to nitrogen gas and nitrous oxide. Nitrous oxide is a powerful greenhouse gas that is most likely to be prevented from being led out to the environment. It is salecies important that the oxidation catalysts 15, 19 can essentially always oxidize nitrogen monoxide to nitrogen dioxide in an amount such that the nitrogen oxide near the SCR catalyst 23 contains as much nitrogen dioxide NO2 as nitrogen monoxide NO.
During operation of the internal combustion engine 2, the exhaust gases are led out through the exhaust line 3. The control unit 17 essentially continuously receives information from the sensors 18 regarding the exhaust gas temperature, pressure, flow, etc. Based on this information and information regarding the combustion engine 2 speed and load, the control unit 17 determines using folders or other type of stored information how much of the nitrous oxide in the exhaust gases that need to oxidize to nitrogen dioxide so that the exhaust gases that are led to the SCR catalyst 23, will contain as much nitrogen monoxide NO and nitrogen dioxide NO2.
The second oxidation catalyst 19 is dimensioned so that it itself can oxidize nitric oxide NO to nitrogen dioxide NO2 in an amount as much as nitrogen monoxide NO and nitrogen dioxide NO2 is led to the SCR catalyst 23 when the exhaust gases had a temperature of about 300 ° C and the exhaust stream is laid. During such optimal operating conditions, it is clear that the exhaust gases are only passed through the second oxidation catalyst 19. When the control unit 17 receives information from, e.g. The said sensors 18 which indicate that such an optimal operating condition are present close the valve means 16. Thereby no exhaust gases are passed through the bypass line 14 and the first oxidation catalyst 15. The second oxidation catalyst itself is responsible for the oxidation of nitrogen monoxide NO to nitrogen dioxide NO2.
If the temperature of the exhaust gases drops to an Idgre value and / or species the exhaust flow through the exhaust line increases, it can be stated that the second oxidation catalyst 19 itself does not have the capacity to oxidize nitrogen monoxide to nitrogen dioxide to an extent so that equal nitrogen monoxide NO and nitrogen dioxide NO2 are conducted to SCR. catalyst 23. When the control unit 17 receives information indicating that this is the case, it estimates that a large proportion of the exhaust gases in the exhaust line 3 which need to be passed through the bypass line 14 and the first oxidation catalyst 15 in order for an equal proportion of nitrogen oxide NO and nitrogen dioxide NO2 to be passed to SCR catalyst 23. Since the bypass line 14 has an inlet 14a in a position upstream of the compound turbine 12, exhaust gases with a higher pressure and a higher temperature can be received in the first oxidation catalyst 15 than in the second oxidation catalyst 19. The oxidation of nitrogen monoxide NO to nitrogen dioxide NO2 thus becomes more efficient. in the first oxidation catalyst An in the duck In order for the first oxidation catalyst 15 to obtain a further increased oxidation capacity, it may contain a higher content of noble metal than the second oxidation catalyst 19.
The first oxidation catalyst 15 thus provides a high oxidation capacity similar to that even in unfavorable operating cases, dd. the exhaust gases have a low temperature and the exhaust gas flow is high-I, are able to together with the second oxidation catalyst 19 essentially always be able to supply the desired composition of nitrogen oxides to the SCR catalyst 23. The first oxidation catalyst 15 can thus provide a variable oxidation capacity within a relatively large area. During certain operating cases, the control unit 17 can lead the entire exhaust stream through the bypass line 14 and the first oxidation catalyst 3. During most operating cases, however, some of the exhaust gases are led through the bypass line 14 while a remaining part is led, via the ordinary exhaust line 3, to the compound turbine 12. with the advantage of the capacity to control the valve means 16 to more or less upright the law sh that the exhaust flow through the bypass line 14 can be regulated steplessly or in a relatively large number of fixed steps.
The control unit 17 can control the temperature and flow of the exhaust gases to the first oxidation catalyst 15 in several different ways. At the time when the exhaust flow through the first oxidation catalyst 15 is to be optimized, the control unit 17 adjusts the exhaust brake 13 and expands the valve means 16 maximally so that the entire exhaust flow is passed through the first oxidation catalyst 15. In this case the upstream turbine 4 also has an increased capacity. it also generates a higher exhaust flow. At times when the exhaust temperature is to be raised, the control unit 17 opens the wastegate valve 11 so that hot exhaust gases which have not expanded through the turbine 4 are led into the bypass line 14 and the first oxidation catalyst 15. The bypass line 14 extends around the compound turbine 12 and the exhaust brake 13. 17, the weapon can use the exhaust brake 13 in the exhaust line 3 and the valve means 16 in the bypass line 14 to increase the exhaust gas pressure and thereby influence the temperature of the exhaust gases passed through the first oxidation catalyst 15.
Fig. 2 shows an internal combustion engine 2 with an exhaust line 3 which is largely equipped with the same components as in Fig. 1. We therefore do not make a further review of the common components. A difference is that the exhaust line 3 does not comprise the flagon compound turbine 12. The bypass line 14 extends instead of around a turbine 4 of the turbocharger. The bypass line 14 has an inlet 14a which is coated upstream of the turbine 4 and an outlet which is coated downstream of the turbine 4. The bypass line 14 comprises a first oxidation catalyst 15 and a valve member 16 with which the exhaust flow through the bypass line can be adjusted. The bypass line 14 may have formed a separate unit or formed part of an existing wastegate and the valve means 16 of a wastegate valve 11.
Fig. 3 shows an internal combustion engine with an exhaust line 3 which is largely provided with the same components as in Figs. 1 and 2. We have therefore not had any further review of the common components. The internal combustion engine 2 is in this case a two-stage supercharged engine. The fume which is led to the internal combustion engine 2 is compressed in two stages by a low-pressure compressor 26 and a high-pressure grain compressor 5. A high-pressure turbine 4 drives the high-pressure compressor 5 and a low-pressure turbine 27 drives the low-pressure compressor 26. In this case the exhaust line 3 does not include sticks around the low pressure turbine 27 of the turbocharger. The bypass line 14 has an inlet 14a which is coated upstream of the low pressure turbine 27 and an outlet which is coated downstream of the low pressure turbine 27. The bypass line 14 comprises a first oxidation catalyst and a valve means 16. The invention is not limited to the embodiment described above but can be varied freely within of the claims. 13

权利要求:
Claims (11)
[1]
An arrangement for treating exhaust gases from an internal combustion engine (2), the arrangement comprising an exhaust line (3) which discharges the exhaust gases from the internal combustion engine (2), a turbine (4, 12, 27) with which energy is recovered from the exhaust gases in the exhaust line (3), a bypass line (14) comprising an inlet (14a) where exhaust gases are received from the exhaust line (3) in a position upstream of the turbine (4, 12, 27) and an outlet (14b) where exhaust gases are led back to the exhaust line (3) in a position downstream of the turbine (4, 12, 27), a first oxidation catalyst (15) and a second oxidation catalyst (19) which are adapted to oxidize nitrogen monoxide to nitrogen dioxide in the exhaust line (3), characterized in that it the first oxidation catalyst (15) is arranged in the bypass line (14) and the second oxidation catalyst (19) is arranged in the exhaust line (3) in a position downstream of the bypass line outlet (14b) and that the arrangement comprises a support part (11, 13, 16, 17 ) sum is adapted to regulate flood and / or the temperature of exhaust gases passed through the first oxidation catalyst (15) in the bypass line (14) such that the first oxidation catalyst (15) and the second oxidation catalyst (19) together provide an oxidation of nitrogen monoxide (NO) to nitrogen dioxide (NO2) in an amount sA that the exhaust gases leaving the second oxidation catalyst (19) have a desired separation of nitrogen monoxide (NO) and nitrogen dioxide (NO2).
[2]
Arrangement according to claim 1, characterized in that the second oxidation catalyst (19) is dimensioned so that it itself has the capacity to oxidize nitric oxide (NO) to nitrogen dioxide (NO2) in an amount such that the desired distribution of nitrogen monoxide (NO) and nitrogen dioxide (NO2) is obtained in the exhaust gases which leave the second oxidation catalyst in the event of operation as optimal thrhaling lines to oxidize nitrogen monoxide (NO) to nitrogen dioxide (NO2).
[3]
Arrangement according to one of Claims 1 or 2, characterized in that the third oxidation catalyst (15) has a higher content of a noble metal coating than the other oxidation catalyst (19).
[4]
Arrangement according to any one of the preceding claims, characterized in that said control means comprises at least one valve means (16) in the bypass line (14) and a control unit (17) adapted to control the valve means (16) so that the third oxidation catalyst (15) is flowed through. of a desired proportion of the exhaust flood in the exhaust line (3). i4
[5]
Arrangement according to claim 4, characterized in that said control means avert comprises an exhaust brake (13) arranged in the exhaust line in a position between the inlet (14a) of the bypass line and the outlet (14b).
[6]
An application according to claim 4 or 5, characterized in that the control means comprises at least one sensor (18) adapted to sense a parameter by which the control unit (17) estimates the flow and temperature of the exhaust gases passed through the first oxidation catalyst (15). ).
[7]
7.
[8]
Arrangement according to any one of the preceding claims, characterized in that the turbine draws a turbine (4, 27) of a turbocharger or a compound turbine (12).
[9]
Arrangement according to any one of the preceding claims, characterized in that the arrangement comprises an SCR catalyst (23) arranged in the exhaust line (3) at a position below the second oxidation catalyst (19) with respect to the intended flow direction of the exhaust gases in the exhaust line (3). ).
[10]
An arrangement according to any one of the preceding claims, characterized in that the arrangement comprises a particle filter (20) arranged in a position downstream of the second oxidation catalyst (19) with respect to the intended direction of discharge of the exhaust gases in the exhaust line (3).
[11]
A method for treating exhaust gases from an internal combustion engine (2), wherein the internal combustion engine (2) is connected to an exhaust line (3) comprising a turbine (4, 12, 27) rued as energy is extracted from the exhaust gases in the exhaust line (3). ), a bypass line (14) comprising an inlet (14a) where exhaust gases are received from the exhaust line (3) in a position upstream of the turbine (4, 12, 27) and an outlet (14b) where exhaust gases are led back to the exhaust line (3) in a position downstream of the turbine (4, 12, 27), a first oxidation catalyst (15) and a second oxidation catalyst (19) which are adapted to oxidize nitrogen oxide to nitrogen dioxide in the exhaust line (3), characterized by the steps of arranging the first oxidation catalyst ( 15) in the bypass line (14), to arrange the second oxidation catalyst (19) in the exhaust line (3) in a position downstream of the bypass line outlet (14b) and to regulate the flow and / or temperature of exhaust gases passed through the first oxidation catalyst (15) in bypassl The lead (14) so that the first oxidation catalyst (15) and the second oxidation catalyst (19) together bond an oxidation of nitrogen moraine (NO) to nitrogen dioxide (NO2) in an amount A of the exhaust gases leaving the second oxidation catalyst (19) a desired distribution of nitrogen monoxide (NO) and nitrogen dioxide (NO2).

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引用文献:

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公开号 | 申请日 | 公开日 | 申请人 | 专利标题

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法律状态:
2021-10-12| NUG| Patent has lapsed|

优先权:

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申请号 | 申请日 | 专利标题

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SE1251092A|SE537709C2|2012-09-27|2012-09-27|Arrangement and method for controlling the distribution of nitrogen monoxide and nitrogen dioxide in an exhaust pipe with two oxidation catalysts|SE1251092A| SE537709C2|2012-09-27|2012-09-27|Arrangement and method for controlling the distribution of nitrogen monoxide and nitrogen dioxide in an exhaust pipe with two oxidation catalysts|

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PCT/SE2013/051086| WO2014051500A1|2012-09-27|2013-09-18|Arrangement and method for oxidative aftertreatment of exhausts from a combustion engine|

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DE112013004219.3T| DE112013004219T5|2012-09-27|2013-09-18|Arrangement and method for the oxidative aftertreatment of exhaust gases from an internal combustion engine|