Exhaust gas treatment system and method for treating an exhaust gas stream

专利摘要:
An exhaust gas treatment system arranged for the treatment of an exhaust gas stream is presented. According to the present invention, the exhaust gas treatment system comprises: - a first dosing device arranged to supply a first additive in said exhaust gas stream; a first reduction catalyst device arranged downstream of said first dosing device and arranged to reduce nitrogen oxides in said exhaust gas stream by utilizing said first additive; a particulate filter at least partially comprising a catalytically oxidizing coating, which is arranged downstream of said first reduction catalyst device and is arranged to capture soot particles and to oxidize one or more of nitric oxide and incompletely oxidized carbon compounds in said exhaust stream; a second dosing device arranged downstream of said particle filter and arranged to supply a second additive in said exhaust gas stream; and - a second reduction catalyst device arranged downstream of said second dosing device and arranged for a reduction of nitrogen oxides in said exhaust gas stream by using at least one of said first and said second additives. 3
公开号:SE1450229A1
申请号:SE1450229
申请日:2014-02-28
公开日:2015-08-29
发明作者:Magnus Nilsson；Henrik Birgersson
申请人:Scania Cv Ab；
IPC主号:

专利说明:

TECHNICAL FIELD The present invention relates to an exhaust gas treatment system according to the preamble of claim 1 and a method for exhaust gas treatment according to the preamble of claim 11.
The present invention also relates to a computer program and a computer program product, which implement the method according to the invention.
Background The following background description constitutes a description of the background of the present invention, and thus does not necessarily constitute prior art.
Due to increased government interests regarding pollution and air quality, especially in urban areas, emission standards and emission rules for internal combustion engines have been developed in many jurisdictions.
Such emission or emission standards often constitute sets of requirements which define acceptable limits on exhaust emissions from internal combustion engines in, for example, vehicles. For example, levels for emissions of nitrogen oxides NOR, hydrocarbons CRHy, carbon monoxide CO and PM particles are often regulated for most types of vehicles in these standards. Vehicles equipped with internal combustion engines typically give rise to these emissions to varying degrees. This document describes the invention mainly for its application in vehicles. However, the invention can be used in essentially all applications where internal combustion engines are used, for example in vehicles, such as in ships or aircraft / helicopters, whereby rules and / or 2 standards for these applications limit the emissions from the internal combustion engines.
In a penalty to meet such emission standards, the exhaust gases caused by the combustion engine's combustion are treated (purified).
A common way of treating exhaust gases from an internal combustion engine consists of a so-called catalytic purification process, for which vehicles equipped with an internal combustion engine usually comprise at least one catalyst. There are different types of catalysts, where the different and different types can be suitable depending on, for example, which combustion concepts, combustion strategies and / or industry types are used in the vehicles and / or which types of compounds in the exhaust stream are to be purified. For at least nitrous gases (nitrogen monoxide, nitrogen dioxide), referred to in this document as nitrogen oxides NOR, vehicles often include a catalyst in which an additive is supplied to the exhaust stream resulting from the combustion engine combustion to achieve a reduction of nitrogen oxides NO mainly to nitrogen gas and water vapor. This is described in more detail below.
A common type of catalyst for this type of reduction, especially for heavy vehicles, Or SCR (Selective Catalytic Reduction) catalysts. SCR catalysts usually use ammonia NH3, or a composition from which ammonia can be generated / formed, as an additive which is used for the reduction of the nitrogen oxides NO in the exhaust gases. The additive is injected into the exhaust stream resulting from the internal combustion engine and tightened on the catalyst. The additive fed to the catalyst is adsorbed (stored) in the catalyst, in the form of ammonia NH3, whereby a redox reaction 3 can take place between nitrogen oxides NO in the exhaust gases and ammonia NH3 available through the additive.
A modern internal combustion engine is a system where there is a collaboration and mutual impact between the engine and exhaust gas treatment. In particular, there is a link between the ability to reduce nitrogen oxides NO in the exhaust gas treatment system and the fuel efficiency of the internal combustion engine. For the internal combustion engine, there is also a connection between the engine's industry efficiency / efficiency and its produced nitrogen oxides NOR. This connection indicates that for a given system there is a positive connection between produced nitrogen oxides NO and the fuel efficiency, it viii to say that an engine that is allowed to emit more nitrogen oxides NO can be phased to consume less fuel by, for example, the injection time can be chosen more optimally. a higher combustion efficiency. Correspondingly, there is a negative connection between a produced particulate mass PM and the fuel efficiency, which means that an increased emission of particulate mass PM from the engine is linked to an increase in fuel consumption. These relationships form the background for the widespread use of exhaust gas treatment systems including an SCR catalyst, where it is intended to optimize the industry and particulate matter against a relatively larger amount of nitrogen oxides NOR produced. A reduction of these nitrogen oxides NO is then carried out in the exhaust gas treatment system, which may therefore comprise an SCR catalyst. Through an integrated approach to the design of the engine and exhaust gas treatment system, where engine and exhaust gas treatment complement each other, a high industry efficiency can therefore be achieved together with legal emissions of both PM and nitrogen oxides NOR. Brief Description of the Invention To some extent, the performance of the exhaust gas treatment systems can be increased by increasing the substrate volumes contained in the exhaust gas treatment systems, which in particular reduces the losses due to uneven distribution of the exhaust gas flow through the substrates.
At the same time, a larger volume of substrate gives a greater back pressure, which to some extent can counteract gains in industry efficiency from the higher degree of conversion. Larger substrate volumes also entailed an increased cost. It is therefore important to be able to make optimal use of the exhaust gas treatment systems, for example by avoiding oversizing and / or by limiting the size and / or manufacturing cost of the exhaust gas treatment systems.
The function and efficiency of catalysts in general, and of reduction catalysts in particular, are strongly dependent on the temperature of the reduction catalyst. In this document, a temperature Over reduction catalyst meant a temperature in / at / for the exhaust stream through the reduction catalyst. The substrate will assume this temperature due to its ability to heat exchange. At a low temperature above the reduction catalyst, the reduction of nitrogen oxides NO is typically inefficient. The NO2 / NOx content in the exhaust gases constitutes a certain possibility of increasing the catalytic activity, even at lower exhaust gas temperatures. However, the temperature and the NO2 / NO content over the reduction catalyst are generally responsible for controlling, as it largely depends on factors unknown in advance, for example on how the driver drives the vehicle. For example, the temperature over the reduction catalyst depends on the torque required by a driver and / or a cruise control, on the appearance of the road section on which the vehicle is located and / or on the driver's cross style.
Previously known exhaust gas treatment systems, such as the system described in detail below which many manufacturers have used to meet the Euro VT emission standard (hereinafter referred to as the "EuroVI system"), include an oxidation catalyst, a diesel particulate filter and a reduction catalyst, exhibiting problems of large thermal mass. / the inertia of catalysts / filters and the large thermal mass / inertia of the rest of the exhaust gas treatment system, including for example exhaust pipes, silencers and various connections. For example, for cold starts, both engine and exhaust gas treatment systems are cold, and for load paths from low exhaust temperatures, cid more torque than previously requested, for example cid ldtt city corn overgdr in country road corn or after idle and power take-off operation, above all makes the diesel particulate filter large thermal mass / trogh the temperature of the reduction catalyst is only slowly increased in such previously known exhaust gas treatment systems. This improves, for example in cold starts and in vehicle operation with temperature and / or river transient elements, the function of the reduction catalyst, and thereby thereby the reduction of nitrogen oxides NOR. This accumulation can result in substandard exhaust gas purification, which risks further polluting the environment. In addition, the deterioration of the function of the reduction catalyst increases the risk of non-compliance with requirements set by the authorities on exhaust gas purification. Fuel consumption can also be negatively affected by the impaired function, as fuel energy death may need to be used to, via various temperature-raising Atgarder, increase the temperature and efficiency of the reduction catalyst.
It is an object of the present invention to improve the purification of the exhaust gases in an exhaust gas treatment system, at the same time as the hazardous exposures for achieving a higher industry efficiency are improved.
These objects are achieved by the above-mentioned exhaust gas treatment system according to the characterizing part of claim 1. The object is achieved above by the above-mentioned method according to the characterizing part of claim 11. The object is achieved above by the above-mentioned computer program and the computer program product.
By utilizing the present invention, a more temperature-efficient treatment of the exhaust gases is obtained in that the upstream-mounted first reduction catalyst device in the exhaust gas treatment system according to the invention can operate at more favorable temperatures than the temperatures of the downstream-mounted second reduction catalyst device. For example, when the first reduction catalyst device at cold starts and path pulls from low temperatures has previous operating temperatures at which an effective reduction of nitrogen oxides NO is obtained. Thus, according to the invention, the available heat is utilized in a more energy-efficient way, which results in an earlier and / or more efficient reduction of nitrogen oxides NOR, for example at cold starts and at pathways from low exhaust temperatures, than has been possible with the previously known exhaust gas treatment systems. .
Correspondingly, in certain other operating types, the second downstream mounted reduction catalyst device may operate at more favorable temperatures than the temperatures of the first upstream mounted reduction catalyst device.
By utilizing the invention, different thermal inertia is obtained for the first and the second reduction catalyst device, which means that these first 7 and the second reduction catalyst devices can be optimized differently with respect to activity and selectivity. Thereby, the first and second reduction catalyst devices can be optimized from a system perspective, the viii saga from a perspective that looks at the function of the entire exhaust gas treatment system, and can therefore be used together to provide an overall more efficient purification of the exhaust gases than the separately optimized catalysts could have provided . These optimizations of the first and second reduction catalyst devices according to the invention can be used to provide this overall more efficient purification in, for example, cold start, but also in substantially all vehicle operation, since temperature and / or flow transient elements often occur even in normal vehicle operation. As mentioned above, the invention can also be used for exhaust gas purification in other units than vehicles, such as in different types of vehicles, whereby an overall more efficient purification of the exhaust gases from the unit is obtained.
The present invention utilizes the thermal inertia / mass having the particulate filter to an advantage of the function by, based on this inertia, optimizing the operation of both the first and second reduction catalyst devices. The present invention thereby provides an interaction / symbiosis between the first reduction catalyst device, which is optimized for the first thermal mass and the first temperature function / temperature gradient to which it is exposed, and the second reduction catalyst device, which is optimized for the second thermal mass and the second temperature course. to which it is exposed.
The first reduction catalyst device and / or the second reduction catalyst device can thus be optimized optimally on properties, for example catalytic properties, for the second reduction catalyst device and / or the first reduction catalyst device. For example, the second reduction catalyst device can be designed / selected so that its catalytic properties at low temperatures become less efficient, which means that its catalytic properties at high temperatures can be optimized. If these catalytic properties of the second reduction catalyst device are taken into account, then the catalytic properties of the first reduction catalyst device can then be optimized in such a way that it does not have to be as efficient at high temperatures.
These possibilities for optimizing the first reduction catalyst device and / or the second reduction catalyst device mean that the present invention provides an exhaust gas purifier which is suitable for emissions which occur in essentially all types of precipitation, especially for strongly transient operation which gives a varying temperature and / or river profile. . Transient operation can, for example, include relatively many starts and decelerations for the vehicle or relatively many up and downhill slopes. Since relatively many vehicles, such as houses which often stop at hallways and / or vehicles which are driven in city traffic or hilly topography, experience such transient operation, the present invention provides an important and very useful exhaust gas purification, which overall reduces the emission from the vehicles in which it implemented.
The present invention thus utilizes the previously problematic thermal mass and the heat exchange has primarily the particulate filter in the EuroVI system as a positive property. The exhaust gas treatment system according to the present invention can, in the same way as the EuroVI system, contribute heat to the exhaust stream and the downstream mounted catalyst catalyst device for shorter periods of slack or other low temperature operation if this low temperature operation has been carried out by higher operating temperatures. The particulate filter is then, due to its thermal inertia, hotter than the exhaust stream, so that the exhaust stream can be heated by the particulate filter.
In addition, this good property is supplemented by the fact that the first reduction catalyst device located upstream, especially in transient operation, can utilize the higher temperature which arises at path drag. Thus, the first reduction catalyst device experiences a higher temperature after the path than the second reduction catalyst device experiences. This higher temperature of the first reduction catalyst device is utilized by the present invention to improve the NOx reduction of the first reduction catalyst device. The present invention, which utilizes two reduction catalyst devices, can utilize both of these positive properties by providing an option for NOx reduction with a small thermal inertia, i.e. the exhaust gas treatment system according to the invention comprises both a NOx conversion and a star thermal inertia. NOx conversion downstream a star thermal inertia. The exhaust gas treatment system of the present invention can then utilize available heat to the maximum in an energy efficient manner, which means that in addition to the rapid and "unfiltered" heat experienced by the first upstream reduction catalyst device, it can be used to make the exhaust gas treatment system of the invention efficient. The exhaust gas treatment system according to the present invention has the potential to meet the emission / emission requirements of the Euro VI emission standard. In addition, the exhaust gas treatment system of the present invention has the potential to meet the emission / emission requirements of several other existing and / or future emission standards.
The exhaust gas treatment system of the present invention can be made compact, since in relation to the degree of performance / purification it can deliver, it comprises few units in the exhaust gas treatment system. These relatively few units, for a well-balanced exhaust purification system according to the present invention, also do not need to be large in volume. As the number of units, and the size of these units, are kept down by the present invention, the exhaust back pressure can also be limited, which results in lower fuel consumption for the vehicle. Catalytic performance per unit volume of substrate can be exchanged for a smaller volume of substrate to obtain some catalytic purification. For an exhaust gas purifier with a predetermined size and / or a predetermined external geometry, which is often the case in vehicles with limited space for the exhaust gas treatment system, a smaller volume of substrate means that a larger volume than the predetermined size for the exhaust purifier can be used for splitting, mixing and irrigation. the exhaust tension under the exhaust gas purification device. This means that the exhaust back pressure can be reduced if an exhaust purifier with a hazardous size and / or a predetermined external geometry is increased in performance per unit volume unit. Thus, the total volume of the exhaust gas treatment system of the invention can be reduced compared with at least some prior art systems. Alternatively, the exhaust back pressure can be reduced by utilizing the present invention. By utilizing the present invention, the need for an Exhaust Gas Recirculation (EGR) system can also be reduced or completely eliminated. Reducing the need for utilization of exhaust gas pipeline systems has, among other things, hazardous parts related to robustness, gas exchange complexity and power output.
In the new manufacture of vehicles, the system of the present invention can be easily assembled at a limited cost, since the separate oxidation catalyst DOC, the viii saga the separate substrate for the oxidation catalyst DOC and the incorporation of this substrate, which existed in prior art systems during manufacture, are then replaced by the the first reduction catalyst device of the present invention. Even retrofitting of an exhaust gas treatment system according to the present invention can be easily performed, since the oxidation catalyst DOC present in prior art systems can be replaced by the first reduction catalyst device according to the present invention even in already manufactured vehicles. An additional dosing device 371 will be required. It may also be required that the particulate filter be replaced or that the properties of its catalytic coating be adjusted. In order to achieve a sufficient nitrogen dioxide-based (NO2-based) soot oxidation, the engine ratio between nitrogen oxides and soot (NOx / soot ratio), as well as the control of the reducing agent dosing by means of the first upstream mounted dosing device in the exhaust gas treatment system according to the invention, must meet certain criteria.
The oxidizing coating, for example comprising noble metal, which in EuroVI systems is in the oxidation catalyst DOC can according to an embodiment of the invention be at least partially implemented, for example in the diesel particulate filter DPF, whereby conditions for a sufficient NO2-based sotoxidation can be obtained. This results in a compact design of the exhaust gas treatment system according to the invention. By using a diesel particulate filter DPF with oxidation catalyst properties, an increased danger predictability for the formation of nitrogen dioxides NO2 can also be obtained.
This is because deactivation of the catalytically active states, such as, for example, deactivation caused by phosphorus, often exhibits an axial concentration gradient. This means that catalysts of relatively short physical length may be more susceptible to these poisonings than catalysts of greater physical length. Since, for example, noble metal, such as Platinum, is added to the physically long diesel particulate filter DPF, instead of the physically shorter oxidation catalyst DOG, more stable levels of nitrogen dioxide NO2 can potentially be obtained over time.
According to an embodiment of the present invention, the first reduction catalyst device constitutes an at least partially protective substrate upstream of an oxidizing coating, where the oxidizing coating can be included in a particle filter coated with, for example, noble metal. According to one embodiment, the catalytic coating of the first reduction catalyst device can be chosen robustly against chemical poisoning, which over time can give a more stable level of the ratio between nitrogen dioxide and nitrogen oxides NO2 / NO x which reach the second reduction catalyst device. The catalytic coating which is protected may, according to an embodiment, also be included in a so-called combination, which is described in more detail below.
The present invention also has an advantage in that two dosing devices cooperating are used in combination for dosing the reducing agent, for example urea, upstream of the first and second reducing catalyst devices, which relieves and facilitates mixing and possible evaporation of the reducing agent, since the injection of the reducing agent is distributed between positions. This reduces the risk of the reducing agent locally cooling down the exhaust gas treatment system, which can potentially form deposits at the positions where the reducing agent is injected, or downstream of these positions.
The relief of the evaporation of the reducing agent means that the exhaust back pressure can potentially be reduced as the requirement for NOx conversion per reduction step is reduced, whereby the amount of reducing agent that must be evaporated is reduced and the injection of the reducing agent is distributed between two positions, compared to the previous single dosing position. It is also possible with the present invention to reduce, or completely switch off, dosing in one dosing position in order to then heat away any precipitates which may occur. As a result, for example, a larger amount of dosage (a more abundant dosage) in the first dosing position of the first reduction catalyst device can be allowed, since any precipitates can be heated away at the same time as the emission requirements are met by the second reduction catalyst device in the meantime. This larger / more abundant dosage can be seen as a more aggressive dosage, which gives dosage amounts closer / above a dosage limit value at which a risk of precipitation / crystallization of additives arises.
As a non-limiting example, if the only dosing device in the EuroVI system had been optimized to provide an evaporation and distribution of the reducing agent which gives 98% NOx conversion, then the NC) conversion of the two respective reduction catalyst devices in the exhaust gas treatment system of the present invention invention is collected, for example to 60% and 95%, respectively. The amounts of reducing agent cid maste 14 farangas in the respective two positions become lower, and the distributions of the reducing agent need not be as optimized in the system according to the invention as in the EuroVI system. An optimal and homogeneous distribution of the reducing agent, as required by the EuroVI system, often gives a high exhaust back pressure because an advanced evaporation / mixing must be used when the reducing agent is to be mixed with the exhaust gases, as is the case with nitrogen oxides NOR. Since not as high demands on optimal and homogeneous distribution of the reducing agent are placed on the system according to the present invention, there is a possibility to lower the exhaust back pressure when the present invention is used.
The two dosing positions used in the present invention thus allow a total of more additives to be added to the exhaust stream than if only one dosing position had been used in the system. This means that improved performance can be provided.
The present invention thus provides a relief of the mixture and the possible evaporation. On the one hand, the double dosing positions allow the reducing agent to be mixed and possibly evaporated in two positions instead of in a position as in the EuroVI system, and on the other hand, the double dosing positions allow lower conversion rates and clamed dosing with less unfavorable gear ratio.
The influence of the size of the conversion rates and the dosage variation is described in more detail below.
In addition, for embodiments which utilize additives in liquid form, the evaporation cid the system according to the invention is utilized. This is partly due to the fact that the total amount of additives to be supplied to the exhaust gas stream is divided into two physically separate dosing positions and partly because the system can be loaded harder than systems with only one dosing position. The system can be loaded harder because the dosage in the position where residues of additives may arise if necessary can be reduced / shut down with the system according to the invention, at the same time as criteria for the total emissions can be met.
The exhaust gas treatment system of the present invention also provides robustness against failure of a metered amount of reducing agent. According to an embodiment of the present invention, a NOR sensor is placed between the two dosing devices in the exhaust gas treatment system. This makes it possible to correct a possible dosing error in the first dosing device during dosing with the second dosing device.
Table 1 below shows a non-limiting example of which conversion rates and emissions result from a 10% dosing error for the reducing agent for a case of 10 g / kWh NOR. In the system with a reduction step, 98% NOR conversion is requested according to the example. To provide 98% NOR conversion in the two-stage exhaust gas treatment system, 60% NOR conversion is required for the first reduction catalyst device and 95% NOR conversion for the second reduction catalyst device. As shown in the table, a system with a reduction step, as for example in the Euro-VI system, gives the emission 1.18 g / kWh. Iva reduction step, as in a system according to the present invention, gives the figure according to the example 0.67 g / kWh. This considerably lower resultant emission for the system of the present invention is the mathematical result of the use of the two dosing points / reduction steps, as shown in Table 1. The NOR sensor placed between the two dosing devices gives this possibility to correct for the 16 dosing error at the first dosing device when the dosing with the second dosing device is done.
Required conversion rate Achieved conversion. degree with 10% dose error Achieved Emission [g / kWh] One red. Step 98% 88.2% I 1.18 Two eds. Step 98% Step 1 - 60% 54.0% 4.60 Step 2 - 95% 85.5% I.
Table 1 This embodiment can be implemented with an added addition in complexity, since a NOR sensor that already exists in today's EuroVI system can be used for the correction. The NOR sensor is normally located in the muffler inlet. Since the first reduction catalyst device and its first dosage in the present invention do not necessarily have to remove all nitrogen oxides NO from the exhaust stream, the first reduction catalyst device and its first dosage may possibly survive without measured information on nitrogen oxides NOR upstream of the first reduction catalyst device.
Correct information, the viii saga information with relatively high accuracy, about nitrogen oxides NO upstream of the second reduction catalyst device Or important to obtain, since the emission in the second reduction catalyst device should be reduced to low levels, often to levels close to zero. This position, i.e. the position at or upstream of the second reduction catalyst device, therefore according to an embodiment of the invention is suitably farmed with a NOR sensor. This NOR sensor can thus, according to the embodiment, be placed downstream of the particle filter, which Oven is a less aggressive environment from a chemical poisoning perspective, compared to one million upstream of the particle filter.
In addition, an adaptation / calibration of several NOx sensors in the exhaust gas treatment system can be easily performed in the system according to the present invention, since the sensors can be exposed to the same NOx level while the emission levels can be kept at reasonable levels during the adaptation / calibration. For the EuroVI system, for example, the adaptation / calibration has often meant that the emissions have become too high during, and even partly after, the actual adaptation / calibration.
As mentioned above, the first and second reduction catalyst devices can be optimized individually, and taking into account the function of the entire exhaust gas treatment system, which can provide an overall very efficient purification of the exhaust gases. This individual optimization can also be used to reduce one or more of the volumes occupied by the first and second reduction catalyst devices, thereby obtaining a compact exhaust purification system.
For the above-mentioned non-limiting example, where the NOR conversion corresponding to the two respective dosing devices in the exhaust gas treatment system according to the present invention can be constituted by 60% and 95%, respectively, the exhaust gas treatment system according to the invention theoretically requires an equal total volume for the first and second reduction catalyst devices. in the EuroVI system requirements to provide a NOx conversion corresponding to 98% with only one reduction catalyst. In practice, however, the requirements of the EuroVI system at the high conversion rate of 98% will require a larger catalyst volume than the catalyst volumes corresponding to the sum of the lower conversion rates of 60% and 95%, respectively, according to the present invention. This is due to a joke lines relationship between volume and conversion rate. At high conversion rates, such as 98%, imperfections in the distribution of exhaust gases and / or reducing agents affect the requirement for catalyst volume to a greater extent. High conversion rates further require a larger catalyst volume and the high conversion rates result in a higher storage / filling rate of reducing agent on the catalyst surface. This stored reducing agent then risks desorbing in certain exhaust gas conditions, it is said that a so-called ammonia slip can occur.
An example of the effect of distribution of the reducing agent and the effect of increasing NH3 slip is shown in Figure 6. The figure shows that the gear ratio, the said slope / derivative, decreases the degree of conversion (y-axis to left) in relation to stoichiometry (x- axis) at high conversion rates, that is to say that the curve for the conversion rate flattens out for high conversion rates, which is partly due to imperfections in the distribution of exhaust gases and / or reducing agents. The figure also shows that an increase in NH3 slip (y-axis to the right) occurs at higher conversion rates. At the right value of one (1) for stoichiometry, more reducing agents are added than what is theoretically behaved, which also increases the risk of NH3 slip.
The present invention makes it possible, according to one embodiment, to control a ratio of NO2 / NO x between the amount of nitrogen dioxide NO2 and the amount of nitrogen oxides NO for the second reduction step, which enables the system to avoid increasing the value of this ratio, for example to avoid NO2 / NO x> 50. %, 19 and that the system, by increasing the dosage, can increase the value for the NO2 / NOR ratio when the value is set, for example am NO2 / NOR <50%. The value of the hazard NO2 / NOR may have, for example by utilizing an embodiment of the present invention, Okas by reducing the level of nitrogen oxides NOR. The NO2 / NOR ratio can assume the storage value, for example after the system has been aged for some time. The present invention thus provides an opportunity to counteract the time accumulated, and gives the system the negative property, which per se improves the value of the NO2 / NOR ratio. By utilizing the present invention, the content of nitrogen dioxide NO2 can thus be actively controlled, which is made possible by the NOR level being adjusted upstream of the catalytically oxidizing coating, for example including noble metal, in the particulate filter 320. This control of the NO2 / NOR ratio can, in addition to catalytic performance advantages , also provide an opportunity to reduce emissions of nitrogen dioxide NO2, which per a very toxic and strongly malodorous emission. This can provide benefits in the event of a future introduction of a separate legal requirement for nitrogen dioxide NO2, as well as the opportunity to reduce harmful emissions of nitrogen dioxide NO2. This can be compared with, for example, the EuroVI system, in which the proportion of nitrogen dioxide NO2 provided during exhaust gas purification is not affectable in the exhaust gas treatment system itself.
In other words, the active control of the content of nitrogen dioxide NO2 is made possible by utilizing the present invention, where the active control can be used by increasing the content of nitrogen dioxide NO2 at the caftans for which it is necessary. As a result, an exhaust gas treatment system can be selected / specified, which, for example, requires less precious metal and thus is also cheaper to manufacture.
If the proportion of the total conversion of nitrogen oxides NO that takes place via a fast reaction wave, the viii saga via fast SCR ("solid SCR") where the reduction takes place via reaction waves Over both nitrogen oxide NO and nitrogen dioxide NO2, can be increased by the active control of the content nitrogen dioxide NO2 as described above can also reduce the requirements for catalyst volume. According to one embodiment of the present invention, the first reduction catalyst device in the exhaust gas treatment system is active at a lower reduction temperature range than the oxidation temperature range Tax required for the nitrogen dioxide-based sotoxidation in the particle filter cDPF. As an example it can be mentioned that the nitrogen dioxide-based sotoxidation in the particle filter DPF can take place at temperatures exceeding 27 ° C. As a result, the reduction of nitrogen oxides NO in the first reduction catalyst device does not compete significantly with the sotoxidation in the particulate filter DPF because they are active with at least partially different temperature ranges TredI. For example, a selected and optimized first reduction catalyst device can provide a significant conversion of nitrogen oxides NO even at about 200 ° C, which means that this first reduction catalyst device does not have to compete with the particle filter sotoxidation performance.
By utilizing the present invention, secondary emissions such as emissions of ammonia NH3 and / or nitrous oxide (nitrous oxide) N2O can also be reduced in relation to a given degree of conversion and / or a given NOx level. A catalyst, for example an ASC (Ammonia Slip Catalyst), which may be included in the second reduction step if the emissions for certain jurisdictions are to be reduced to very low levels, may have a certain selectivity towards, for example, nitrous oxide N20, which causes the NOx level to decrease by utilizing 21 the further reduction step according to the present invention also shifts down the resulting levels of nitrous oxide N 2 O. The resulting levels of ammonia NH 3 can be lowered in the corresponding manner in which the present invention is utilized.
BRIEF DESCRIPTION OF THE DRAWINGS The invention will be further elucidated below with reference to the accompanying drawings, in which like reference numerals are used for like parts, and are shown: Figure 1 shows an exemplary vehicle which may include the present invention, Figure 2 shows a traditional exhaust treatment system; the present invention, Figure 4 shows a flow chart of the exhaust gas treatment process of the present invention, Figure 5 shows a control unit according to the present invention, Figure 6 shows, inter alia, a ratio between NOx conversion and NH3 grinding.
Description of Preferred Embodiments Figure 1 schematically shows an exemplary vehicle 100 including an exhaust gas treatment system 150, which may be an exhaust gas treatment system 150 in accordance with an embodiment of the present invention. The driveline comprises an internal combustion engine 101, which in a conventional manner, via a shaft 102 extending on the internal combustion engine 101, usually via a flywheel, is connected to a gear shaft 103 via a clutch 106.
The internal combustion engine 101 is controlled by the control system of the vehicle via a control unit 115. Likewise, the clutch 106 and the gearbox 103 can be controlled by the control system of the vehicle by means of one or more suitable control units (not shown). Of course, the vehicle's driveline can also be of a different type, such as a type with conventional automatic transmission, of a type with a hybrid driveline, etc.
A shaft 107 emanating from the shaft shaft 103 drives the drive wheels 113, 114 via an end shaft 108, such as e.g. a conventional differential, and drive shafts 104, 105 connected to said end shaft 108.
The vehicle 100 further includes an exhaust gas treatment system / exhaust purification system 150 for treating / purifying exhaust emissions resulting from combustion in the combustion chamber of the internal combustion engine 101, which may be discharged from cylinders.
Figure 2 shows a previously known exhaust gas treatment system 250, which can illustrate the above-mentioned EuroVI system, and which with an exhaust line 202 is connected to an internal combustion engine 201, where the exhaust gases generated during combustion, i.e. the exhaust stream 203, are indicated by arrows. The exhaust stream 203 is led to a Diesel Particulate Filter (DPF) 220 via a Diesel Oxidation Catalyst (DOC) 210. During combustion in the internal combustion engine, soot particles are formed, and the DPF 220 particulate filter is used to capture these soot particles. The exhaust stream 203 is passed through a filter structure where soot particles are captured from the passing exhaust stream 203 and stored in the particulate filter 220. 23 The oxidation catalyst DOC 210 has several functions and is normally used primarily to oxidize the residual hydrocarbons CHy (COG)). 203 to carbon dioxide CO2 and water H20.
The oxidation catalyst DOC 210 can also oxidize a large proportion of the nitrogen monoxides NO present in the exhaust stream to nitrogen dioxide NO2. The oxidation of nitrogen monoxide NO to nitrogen dioxide NO2 is important for the nitrogen dioxide-based sotoxidation in the filter and is further advantageous in the event of a subsequent reduction of nitrogen oxides NOR. In this regard, the exhaust gas treatment system 250 further comprises an SCR (Selective Catalytic Reduction) catalyst 230 arranged downstream of the particulate filter DPF 220. SCR catalysts use ammonia NH 3, or a composition from which ammonia can be generated / formed, such as e.g. urea, as an additive to reduce the amount of nitrogen oxides NOx the exhaust gas strain. However, the reaction rate of this reduction is affected by the ratio of nitrogen monoxide NO to nitrogen dioxide NO2 in the exhaust stream, after which the reaction of the reduction is affected in the positive direction by previous oxidation of NO to NO2 in the oxidation catalyst DOC. This applies up to an arde corresponding to approximately 50% for the molar ratio NO2 / NO. For higher proportions for the molar ratio NO2 / NO, ie for the arden in excess of 50%, the reaction rate is strongly negatively affected.
As mentioned above, the SCR catalyst 230 requires additives to reduce the concentration of a compound such as nitrogen oxides NO in the exhaust stream 203. This additive is injected into the exhaust stream and the SCR catalyst 230 is tightened (not shown in Figure 2). This additive is often ammonia- and / or urea-based, or consists of a substance from which ammonia can be extracted or released, and can for example 24 be bested by AdBlue, which in principle emits urea mixed with water. Urea forms ammonia partly on heating (thermolysis) and partly on heterogeneous catalysis on an oxidizing surface (hydrolysis), which can be formed, for example, from titanium dioxide TiO 2, including the SCR catalyst. The exhaust gas treatment system can Sven include a separate hydrolysis catalyst.
The exhaust gas treatment system 250 is also provided with an Ammonia Slip Catalyst (ASC) which is arranged to oxidize an excess of ammonia which can remain after the SCR catalyst 230 orb, oiler a 1 bts A SCR. the catalyst with terii.gre Nr), - reducto. As a result, the grinding catalyst ASC can provide an opportunity to improve the system's overall NOx conversion / reduction.
The exhaust gas treatment system 250 is also provided with one or more sensors, such as one or more NOR and / or temperature sensors 261, 262, 263, 264 for determining nitrogen oxides and / or temperatures in the exhaust gas treatment system.
The previously known exhaust gas treatment system shown in Figure 2, i.e. the EuroVI system, has a problem in that catalysts are efficient heat exchangers, which together with the rest of the exhaust system, including for example exhaust pipe 202 and materials and space for sound evaporation and various connections, have a large thermal mass / inertia. At the start of the catalyst temperature Or below its optimum working temperature, which can for example be about 300 ° C, and at paddles from low exhaust gas temperatures, which can occur for example when light city corn turns into country road corn or after idle and power take-off operation, the exhaust temperature is filtered by this large thermal mass . This affects the function, and thereby the efficiency of the reduction of, for example, nitrogen oxides NO of the SCR catalyst 230, which may result in a substandard exhaust gas purification being provided by the system shown in Figure 2. This means that a smaller amount of released nitrogen oxides NO can be allowed to escape from the engine. 101 the exhaust gas purification had been efficient, which could lead to demands for a more complex engine and / or a lower industry efficiency.
In the previously known exhaust gas treatment system, there is also a risk that the relatively cold reducing agent locally cools down the exhaust pipe parts and thus can give rise to precipitations. This risk of precipitation downstream of the injection is likely to be due to the amount of reducing agent injected.
Among other things, to compensate for the limited supply of heat / temperature during, for example, cold starts and operation with low loads, so-called fast SCR ("fixed SCR") can be used, in which the reduction is controlled to the greatest extent possible via reaction waves. both nitrogen oxide NO and nitrogen dioxide NO2. In rapid SCR, the reaction uses equal parts nitrogen monoxide NO and nitrogen dioxide NO2, which means that an optimal value of the molar ratio NO2 / NO x is close to 50%.
For certain catalyst temperature and flow conditions, i.e. for a certain residence time in the catalyst ("Space Velocity"), there is a risk that a non-advantageous proportion of nitrogen dioxide NO2 is obtained. In particular, there is a risk that the NO2 / NO x ratio exceeds 50%, which can be a real problem for exhaust gas purification. An optimization of the NO2 / NO x ratio for the above-mentioned critical low-temperature operating cases thus risks giving an excessively high proportion of nitrogen dioxide NO2 in other operating cases at, for example, higher temperatures. This higher proportion of nitrogen dioxides NO2 results in greater volume cracking for the SCR catalyst 26 and / or in a limitation of the amount of nitrogen oxides emitted from the engine and thus in a lower fuel efficiency for the vehicle. In addition, there is a risk that the lower proportion of nitrogen dioxide NO2 will also result in emissions of nitrous oxide N20.
These risks that a non-hazardous proportion of nitrogen dioxide NO2 arises also exist due to aging of the system. For example, the NO2 / NO x ratio can assume lower values when the system has aged, which may mean that a catalyst specification which in the unmodified state gives excessively high proportions of NO2 / NO x must be used to increase, and be able to compensate for, the aging.
Also a lack of control robustness against dosing errors for the amount of reducing agent and / or a lack of control robustness against a sensor error display can at high NOx conversion rates be a problem for the exhaust gas treatment system.
In the previously known solution described in US2005 / 0069476 it is proposed that the exhaust system should consist of a narcotized SCR catalyst (ccSCR), which should be connected close, less than 1 meter, from the exhaust outlet of the engine or turbo, downstream followed by a SORT system. The SCRT system is defined by the authors of US2005 / 0069476 as a prior art system in the direction of the exhaust stream which includes a DOC catalyst, a DPF filter, a urea dosing device, and an SCR catalyst. Thus, the exhaust gas treatment system described in US2005 / 0069476 in turn consists in the flow direction of the exhaust strip of the following separate components: the anesthetized ccSCR catalyst, the DOC catalyst, the DPF filter, and the SCR catalyst; ccSCR-DOC-DPF-SCR.
According to the solution in US2005 / 0069476, the anesthetized ccSCR catalyst must be mounted close to the engine and / or turbo in order to minimize the impact of the thermal mass / inertia of the exhaust pipe 27 and / or the exhaust gas treatment system, as this thermal mass / inertia impairs the exhaust gas treatment properties of the exhaust gas treatment system. . Nevertheless, there is a risk that the solution described in US2005 / 0069476 will have a performance problem because neither the connected ccSCR catalyst nor the subsequent SCR catalyst are optimized for cooperating exhaust gas purification. The subsequent SCR catalyst Or in US2005 / 0069476 is the same catalyst as has previously been used in the SCRT system, which means that this subsequent SCR catalyst can be both unnecessarily expensive and not optimized for exhaust gas purification with ccSCR.
In US2005 / 0069476 the disconnected ccSCR catalyst is added to the exhaust gas treatment system to deal with problems related to the cold start, which gives a costly solution directed only to cold starts, because this solution, due to the fact that it contains an additional unit (the ccSCR catalyst ), potentially increases the back pressure in the exhaust gas treatment system and thus potentially increases fuel consumption. Potentially, therefore, fuel consumption increases in other operations on cold starts, such as for motorway operation, which means more efficient power consumption and an often greater contribution to the total fuel consumption.
These problems for the system described in US2005 / 0069476 are at least partially addressed by the present invention.
Figure 3 schematically shows an exhaust gas treatment system 3 according to the present invention which with an exhaust line 302 is connected to an internal combustion engine 301. Exhaust gases generated during the combustion in the engine 301 and the exhaust stream 303 (indicated by arrows) are led to a first metering device 371 arranged to supply a first in the exhaust stream 303. A first reduction catalyst device 28 331 is provided downstream of the first metering device 371. The first reduction catalyst device 331 is arranged to reduce nitrogen oxides NO in the exhaust stream 303 by utilizing the first additive fed to the exhaust gas stream in the 371. first reduction catalyst device 371 an additive, for example ammonia NH3 or a substance, from which ammonia can be generated / formed / released, in the reduction of the nitrogen oxides NO in the exhaust stream 303. This additive may, for example, consist of the above-mentioned AdBlue.
According to an embodiment of the invention, a first hydrolysis catalyst, which may consist of essentially any suitable hydrolysis coating, and / or a first mixer may be arranged in connection with the first dosing device 371. The first hydrolysis catalyst and / or the first mixer is used to Increase the rate of decomposition of urea to ammonia and / or to mix the additive with the emissions and / or to evaporate the additive.
The exhaust gas treatment system 350 of the present invention downstream of the first reduction catalyst device 331 comprises a particulate filter 320, which at least partially comprises a catalytic oxidizing coating. The particulate filter 320 is thus arranged to capture and oxidize soot particles and to oxidize one or more of nitric oxide NO and incompletely oxidized carbon compounds in the exhaust stream 303. The exhaust stream 303 is passed through the filter structure of the particulate filter, which is at least partially oxidized with a catalyst material.
Soot particles are captured in the filter structure from the passing 29 exhaust stream 303 and stored and oxidized in the particulate filter.
According to one embodiment of the invention, the particulate filter 320 is arranged so that the particulate filter 320 is the first exhaust gas treatment system component that the exhaust gas stream 303 passes through the first reduction catalyst device 331. In other words, the particulate filter 320 according to the embodiment is connected downstream. the reduction catalyst device 331 and the particulate filter 320.
As described in more detail below, according to one embodiment, the first reduction catalyst device 331 may comprise a first selective catalytic reduction catalyst SCR ', a first selective catalytic reduction catalyst SCR' downstream followed by a first slip catalyst ASC1 / AMOXI catalytic catalyst, combined with an oxidizing coating in the outlet portion of the same substrate. Since the particulate filter 320 is the first exhaust gas treatment system component that the exhaust gas stream 303 passes through the first reduction catalyst device 331 for this embodiment, essentially no oxidation of nitrogen oxide NO and / or incompletely oxidized carbon compounds occurs between the first reduction catalyst particle device 33.
An advantage of connecting the particulate filter 320 downstream of the reduction catalyst device 331 without intermediate exhaust gas treatment system components, apart from any pipe connections, is that the number of substrates in the exhaust gas treatment system 350 will be smaller than, for example, an oxidation catalyst DOC. to a more compact exhaust treatment system 350 with lower back pressure, which is easier and cheaper to manufacture and / or assemble. In such an exhaust treatment system 350, the first reduction catalyst device 331 provides an upstream protection for the oxidizing bellows of the particulate filter, which can provide a chemical robustness. The chemical robustness is enhanced by the fact that the substrate in the particulate filter 320, i.e. the catalytically oxidizing precipitate in the particulate filter, is relatively physically elongated according to an embodiment of the invention.
The particulate filter cDPF 320, Or at least partially coated with a catalytic oxidizing coating, where this oxidizing coating may comprise at least one part metal. That is, the particulate filter 320 may be at least partially coated with one or more sub-metals, such as platinum.
The particle filter cDPF 320 comprising the oxidizing coating has several advantages compared to a classic particle filter DPF without oxidizing coating.
The particle filter cDPF 320 comprising the oxidizing coating gives an improved NO2-based regeneration of the filter, i.e. an improved NO2-based sotoxidation, which can also be called passive regeneration of the filter. An exhaust gas treatment system comprising a particle filter DPF, i.e. without oxidizing weld, and which does not have an oxidation catalyst DOC between the reduction catalyst and the classical particle filter DPF, a very limited NO2-based oxidation of soot in the filter is obtained. The system according to the embodiment of the present invention intends, by utilizing the oxidizing coated filter, to purify the filter from soot by the NO 2 -based passive regeneration / oxidation. However, the present invention can also be used with the vehicle part in active regeneration of the filter, the viii saga cid regeneration is initiated by an injection, for example by using an injector, of fuel upstream of the filter. During active regeneration, the exhaust gas treatment system according to the invention has the advantage that the first reduction catalyst device itself can handle a certain NOx conversion while the downstream filter called the second reduction catalyst device, due to the regeneration, experiences such a high temperature that it has to reach a high degree of conversion. .
When utilizing the engine injection system in a regeneration of the cDPF particulate filter, the first reduction catalyst device will at least partially assist the cDPF particulate filter by partially oxidizing the fuel to primarily carbon monoxide CO. This simplifies the regeneration of the particle filter cDPF compared to exhaust gas treatment systems which lack a first reduction catalyst device according to the present invention.
The particle filter cDPF 320 which comprises the oxidizing coating gives Oven more stable conditions for the nitrogen dioxide level NO2 at the second reduction catalyst device 332. In addition, the use of the particle filter cDPF 320 comprising the oxidizing coating allows the value of the NO2 / NO2 ratio to be controlled.
Downstream of the particulate filter 320 Or the exhaust gas treatment system 3 provided with a second metering device 372, which Or 32 is arranged to supply a second additive in the exhaust stream 303, this second additive comprising ammonia NH3, or a substance, for example AdBlue, from which ammonia can be generated / formed / released , as described above. The second additive may have been derived from the same additive as the above-mentioned first additive, it being said that the first and second additives are of the same type and may possibly also come from the same tank. The first and second additives may also be of the alike type and may come from different thoughts.
According to an embodiment of the invention, in addition, a second hydrolysis catalyst and / or a second mixer may be arranged in connection with the second dosing device 372. The function and design of the second hydrolysis catalyst and / or the second mixer correspond to those described above for the first hydrolysis catalyst and the understand the mixer.
The exhaust gas treatment system 350 also includes a second reduction catalyst device 332, which is located downstream of the second metering device 372. The second reduction catalyst device 332 is arranged to reduce nitrogen oxides NO in the exhaust stream 303 by utilizing the second additive and, if the first additive is present, when the second reduction catalyst device 332, also by utilizing the first additive.
The exhaust gas treatment system 350 may also be provided with one or more sensors, such as one or more NOx sensors 361, 363, 364 and / or one or more temperature sensors 362, 363, which are arranged for determining NOx concentrations and temperatures in the exhaust gas treatment system 350, respectively. A robustness against failure in metered amount of reducing agent can be achieved by an embodiment of the invention, where a NOx sensor 363 is located between the two metering devices 372, and preferably between the particle filter 320 and the second metering device 372, in the exhaust gas treatment system 350. This makes it possible to by means of the second dosing device 372 correct any dosing error which has created unforeseen emission levels, the first reduction device 371 ° eh and / or the particle filter 320 is down-tightened.
This placement of the NOx sensor 363 between the two dosing devices 371, 372, and preferably between the particle filter cDPF 320 and the second dosing device also makes it possible to correct the amount of additives dosed by the second dosing device 372 for nitrogen oxides NO which can be created over the particle filter cDPF 3. of excess residues of the additive from the dosing challenge of the first dosing device 371.
The NOx sensor 364 downstream of the second reduction catalyst device 332 can be used in feedback of dosing of the additive.
Using the exhaust gas treatment system 350 shown in Figure 3, both the first reduction catalyst device 331 and the second reduction catalyst device 332 can be optimized with respect to a choice of catalyst characteristics for reduction of nitrogen oxides NO and / or with respect to volumes of the first 331 and second 332 reduction catalyst, respectively. By the present invention, the particulate filter 320 is utilized to the advantage of the function by taking into account how its thermal mass affects the temperature of the second reduction catalyst 332 and how its catalytic coating affects the NO2 / NOx content 34, the second reduction catalyst 332 is tightened in the exhaust gas purification.
By taking into account the thermal inertia of the particulate filter 320, the first reduction catalyst device 331 and the second reduction catalyst device 332, respectively, can be optimized with respect to the specific temperature function they will each experience. Since the optimized first 331 and second 332 reduction catalyst devices are designed to co-purify the exhaust gases of the present invention, the exhaust gas treatment system 350 can be compacted. The space set aside for the exhaust gas treatment system 350, for example in a vehicle, is limited, it is a major advantage to provide a compact exhaust gas treatment system by a high degree of utilization of the catalysts used according to the present invention. This high degree of utilization, and the associated smaller volume language, also gives the opportunity for a reduced back pressure and thus also for a lower fuel consumption.
The present invention provides an exhaust gas treatment system 350 which effectively reduces the amount of nitrogen oxides NO in the exhaust stream at substantially all corrugations, including especially cold starts and load path deductions, i.e. increased starting torque, from low exhaust gas temperature and load deduction, i.e. reduced required torque. Thus, the exhaust gas treatment system 350 of the present invention is suitable for substantially all choruses that give rise to a transient temperature course in the exhaust gas treatment. An example of such a choir fall can be city driving which includes many starts and decelerations.
The prior art problems associated with a high proportion of nitrogen dioxides NO2 can be solved at least in part by utilizing the present invention, since two reduction catalyst devices 371, 372 are present in the exhaust gas treatment system 350. The problem can be overcome by combining the present invention with the realization of NOx controls the proportion of nitrogen dioxide NO2 obtained downstream of a filter / substrate coated with a catalytic oxidizing coating, which means that the amount of nitrogen oxides NOx can be used to control the value of the NO2 / NOx ratio.
By reducing the nitrogen oxides NO2 Over the first reduction catalyst device 371 when operating at low temperature, a requirement of a given ratio between nitrogen dioxide and nitrogen oxides NO2 / NO x in the exhaust gases reaching the second reduction catalyst device 372 can be met with a smaller, and thus less expensive, amount of oxidizing coating. .
The present invention has the advantage that the additional manufacturing cost as a result of the invention can be kept at a low level, since the oxidation catalyst DOC 210 present in prior art systems in the manufacture according to an embodiment of the invention can be replaced by the first reduction catalyst device 331 according to the present invention. Thus, a manufacturing step comprising mounting the oxidation catalyst DOC 210 can be easily replaced with another manufacturing step comprising mounting the first reduction catalyst device 331 according to the present invention. This provides a minimal addition to the assembly and / or manufacturing cost.
Since the oxidation catalyst DOC 210 present in prior art systems can be replaced with the first reduction catalyst device 331 according to the present invention Or retrofitting to already manufactured units 36 including exhaust gas treatment systems according to the EuroVI specification is possible. In addition, it is also required that an additional dosing device be mounted in the exhaust gas treatment system, which comprises devices for mixing and / or evaporating the additive.
The first reduction catalyst device 331 in the exhaust gas treatment system 350 is, according to one embodiment, active at a lower reduction temperature range Trect an oxidation temperature range Tox at which the nitrogen dioxide-based sotoxidation, i.e. the oxidation of incompletely oxidized carbon compounds 320, is in the particulate filter. In other words, the temperature of a so-called "light-off" for the sotoxidation in the particulate filter 320 is higher than the "light-off" for the reduction of nitrogen oxides NO in the first reduction catalyst device 331. As a result, the reduction of nitrogen oxides NO in the first reduction catalyst device 331 does not nod. with the sotoxidation in the particulate filter 320 because they are active at least partially different temperature ranges; 'redTox.
The exhaust gas treatment system sometimes requires the engine to generate heat in order for the exhaust gas treatment system to achieve sufficient efficiency with respect to exhaust gas purification. This heat generation is then achieved at the expense of reducing the engine's efficiency in terms of fuel consumption. An advantageous feature of the exhaust gas treatment system according to the present invention is that the first reduction catalyst device upstream of the filter can be phased to react more quickly to this generated heat than has been possible for, for example, the Euro VI system. Therefore, there is less industry overall by utilizing the present invention. According to an embodiment of the present invention, the engine is controlled to generate such heat to an extent such that the first reduction catalyst device reaches a certain given temperature / performance. Thus, efficient exhaust gas purification can be obtained by allowing the first reduction catalyst device to operate at a favorable temperature, while avoiding unnecessary star heating, and thus fuel efficiency.
Unlike the aforementioned prior art solutions, the first reduction catalyst device 331 of the present invention need not be anesthetized to the engine and / or turban. The fact that the first reduction catalyst device 331 according to the present invention can be mounted further from the engine and / or turban, and can for instance sit in the muffler, has an advantage in that a longer mixing distance for additives can be obtained in the exhaust stream between the engine and / or the turban and the first The reduction catalyst device 331. This results in a better utilization rate for the first reduction catalyst device 331. At the same time, the present invention provides the many advantages mentioned in this document with the possibility of reducing nitrogen oxides NO both upstream and downstream of the thermally faithful filter cDPF.
According to various embodiments of the present invention, the first reduction catalyst device 331 comprises any of: a first selective catalytic reduction catalyst SCR; a first selective catalytic reduction catalyst SCR1 downstream integrated with a first slip catalyst ASC1 / AMOX1, wherein the first slip catalyst ASC1 / AMOXlar is arranged to oxidize a residue of additives, where the residue may consist of, for example, urea, ammonia NH3 or isocyanic acid HNCO and / or to be SCR1 helpful in further reducing nitrogen oxides NO in the exhaust stream 303; a first selective catalytic reduction catalyst SCR1 is downstream followed by a separate first slip catalyst ASC1, where the first slip catalyst ASC1 is arranged to oxidize a residue of additives, where the residue may consist of, for example, urea, ammonia NH3 or isocyanic acid HNCO and / or to be SCR 'helpful in further reducing nitrogen oxides NO in the exhaust stream 303; a first slip catalyst ASC1, which is primarily arranged for the reduction of nitrogen oxides NO and secondarily for the oxidation of a residue of additives, (the residue may consist, for example, of urea, ammonia NH3 or isocyanic acid HNCO in the exhaust stream 303; and a first selective catalytic reduction catalyst SCR1 combined with an oxidizing coating in the outlet portion of the same substrate, which is also sometimes referred to as "combicat" / combicat SCRcomb • According to various embodiments, the second reduction catalyst device 332 is composed of any of: a second selective catalytic catalytic reduction catalyst; reduction catalyst SCR2 downstream integrated with a second grinding catalyst ASC2 / AMOX2, where the second grinding catalyst ASC2 / AMOX2 Or is arranged to oxidize a residue of additives and / or to be SCR2 helpful with a further reduction of nitrogen oxides NOx the exhaust stream 303; second selective catalytic reduction catalyst SCR2 downstream followed by a separ at second grinding catalyst ASC2, where the second grinding catalyst ASC2 is arranged to oxidize a residue of additives and / or to be SCR2 helpful with a further reduction of nitrogen oxides NO in the exhaust stream 303.
For both the first 331 and second 332 reduction catalysts, its catalytic properties can be selected based on the environment to which it is, or will be, exposed. In addition, the catalytic properties of the first 331 and second 332 reduction catalyst devices can be adjusted so that they can be allowed to operate in symbiosis with each other. The first 331 and second 332 reduction catalyst devices may further comprise one or more materials which provide the catalytic property. For example, transition metals such as Vanadium and / or Tungsten can be used, for example in a catalyst comprising V / V10 3/10 2 O 2. Even metals such as iron and / or copper can not be present in the first 331 and / or second 332 reduction catalyst device, for example in a zeolite-based catalyst.
The exhaust gas treatment system 350 shown schematically in Figure 3 can thus, according to different embodiments, have a variety of structures / configurations, which can be summarized according to the following paragraphs, and where each unit SCR, SCR2, cDPF, SCRikomb, ASC1, ASC2 has the respective properties shown in this entire document. The particulate filter 320 with the at least partially catalytic oxidizing coating is designated cDPF.
The catalytic oxidizing coating can be adapted to its properties of oxidizing nitrogen oxide NO and oxidizing incompletely oxidized carbon compounds. Incompletely oxidized carbon compounds can, for example, be fuel residues created by the engine's injection system.
According to a configuration according to the invention, the exhaust gas treatment system has the structure SCR-cDPF-SCR2. It is said that the exhaust gas treatment system 350 comprises a first selective catalytic reduction catalyst SCR, downstream followed by a particle filter with an at least partially catalytic oxidizing coating cDPF, downstream followed by a second selective catalytic reduction catalyst SCR2. A symbiotic utilization of both the first selectively catalytic reduction catalyst SCR together with the second selective catalytic reduction catalyst SCR2 the exhaust gas treatment system 350 may allow a second abrasive catalyst ASC2 to be omitted in the exhaust gas treatment system 3 for certain limitations, e.g. degree of conversion. This is an advantage, for example, in comparison with the above-mentioned EuroVI system, in which the grinding catalyst is in practice a requirement. Since an SCR catalyst is typically cheaper than an ASC catalyst, this embodiment of the invention can reduce the manufacturing cost by omitting the second grinding catalyst ASC2. According to a configuration according to the invention, the exhaust gas treatment system has the structure SCR2-ASC1-cDPF-SCR2. It is said that the exhaust gas treatment system 350 comprises a first selective catalytic reduction catalyst SCR ', downstream followed by a first slip catalyst ASC2, downstream followed by a particle filter with an at least partially catalytic oxidizing coating cDPF, downstream followed by a second selective catalytic catalyst. As mentioned above, the use of both the first selective catalytic reduction catalyst SCR 1 and the second selective catalytic reduction catalyst SCR2 allows the exhaust gas treatment system 350 to omit a second slip catalyst ASC2 in the exhaust gas treatment system 350 for certain applications. The utilization of the first slip catalyst ASC1 enables a greater load and thus a better utilization of the first selective catalytic reduction catalyst SCR 1 and also enables a lowering of the starting temperature ("light off" temperature) for the NOx reduction.
According to a configuration according to the invention, the exhaust gas treatment system has the structure SCRlitcmb -cDPF-SCR2. It is said that the exhaust gas treatment system 350 comprises a first selective catalytic reduction catalyst SCR 'combined with an oxidizing coating in the outlet portion of the same substrate (hereinafter referred to as "combicat"), downstream followed by a particulate filter with an at least partially catalytic oxidizing coating. of a second selective catalytic reduction catalyst SCR2. Also, due to the use of both the first selective catalytic reduction catalyst SCR 1 and the second selective catalytic reduction catalyst SCR2, the second grinding catalyst ASC2 can be omitted in the exhaust gas treatment system 350 for certain applications. This exhaust treatment system, the viii saga system with SCR1komb-cDPF-SCR2, can enable a lowering of the starting temperature ("light off" temperature) for the NOx reduction and also has an advantage in that the exhaust temperature can be raised more efficiently in the system by oxidizing the hydrocarbons in the oxidizing part in the outlet part of SCR] comb. Such a temperature increase can be advantageous in a so-called active regeneration of the particle filter with the at least partially catalytic oxidizing coating cDPF.
According to a configuration according to the invention, the exhaust gas treatment system has the structure SCR1-c1DPF-SCR2-ASC2. It is said that the exhaust gas treatment system 350 comprises a first selective catalytic reduction catalyst SCR ', downstream followed by a particle filter with an at least partially catalytic oxidizing coating cDPF, downstream followed by a second selective catalytic reduction catalyst SCR2, a downstream catalyst of ASC. This exhaust gas treatment system 350 enables emission levels of nitrogen oxides NO nOra non, since the second reduction catalyst SCR2 can be heavily loaded, for example by increasing the dosage of the second additive, which is followed downstream of the second grinding catalyst ASC2.
According to a configuration according to the invention, the exhaust gas treatment system has the structure SCR1-ASC1-cDPF-SCR2-ASC2. It is said that the exhaust gas treatment system 350 comprises a first selective catalytic reduction catalyst SCR ', downstream followed by a first slip catalyst ASC1, downstream followed by a particle filter with an at least partially catalytic oxidizing coating cDPF, downstream followed by a second selective catalytic catalytic reduction. followed by a second slip catalyst ASC2. This exhaust gas treatment system 350 enables emission levels of nitrogen oxides NO near zero, since the second reduction catalyst SCR2 can be driven hard, for example by increasing the dosage of the second additive, which it is followed downstream by the second grinding catalyst ASC2. The use of the first slip catalyst ASC1 also makes it possible to lower the starting temperature ("light off" temperature) for the NOx reduction and can also give a greater load and thus a better use of the first selective catalytic reduction catalyst SCR.
According to a configuration according to the invention, the exhaust gas treatment system has the structure SCR1-Komb-cDPF-SCR2-ASC2. It is said that the exhaust gas treatment system 350 comprises a first selective catalytic reduction catalyst SCR 'combined with an oxidizing coating in the outlet portion of the same substrate, downstream followed by a particle filter with an at least partially catalytic oxidizing coating cDPF, downstream followed by a second selective catalytic catalyst. downstream followed by a second grinding catalyst ASC2. This exhaust treatment system 350 also enables a lowering of the starting temperature ("light off" temperature) for the NOx reduction and has an advantage in that the exhaust temperature can be raised more efficiently in the system by oxidizing the hydrocarbons in the oxidizing part in the outlet part of SCR1 comb • A page temperature rise can be advantageous in a so-called active regeneration of the particle filter with the at least partially catalytic oxidizing coating cDPF.
This exhaust gas treatment system 350 also allows emission levels for nitrogen oxides NO to near zero, since the second reduction catalyst SCR2 can be loaded rapidly, for example by increasing the dosage of the second additive, which is followed downstream of the second grinding catalyst ASC2.
According to a configuration according to the invention, the exhaust gas treatment system has the structure ASC2-cDPF-SCR2. That is, the exhaust gas treatment system 350 comprises a first slip catalyst ASC1, downstream followed by a particulate filter with an at least partially catalytic oxidizing coating cDPF, downstream followed by a second selective catalytic reduction catalyst SCR2. Also, due to the utilization of both the first slip catalyst ASC1 and the second selectively catalytic reduction catalyst SCR2, the second slip catalyst ASC2 may be omitted in the exhaust gas treatment system 350 for certain applications. The utilization of the first slip catalyst ASC1 makes it possible to lower the starting temperature ("light off" temperature) for the NOx reduction.
According to a configuration according to the invention, the exhaust gas treatment system has the structure ASC1-cDPF-SCR2-ASC2. It is said that the exhaust gas treatment system 350 comprises a first slip catalyst ASC1, downstream followed by a particulate filter with an at least partially catalytic oxidizing coating cDPF, downstream followed by a second selective catalytic reduction catalyst SCR2, downstream followed by a second slip catalyst ASC2. This exhaust gas treatment system allows emission levels of nitrogen oxides NO to near zero, since the second reduction catalyst SCR2 can be heavily loaded, i.e. with a relatively high dosage of the second additive, which is followed downstream by the second abrasive catalyst ASC2. The use of the first slip catalyst ASC1 makes it possible to lower the starting temperature ("light off" temperature) for the NOx reduction.
In the above-listed configurations of the embodiments, as described above, the first reduction catalyst SCR 1 and the first grinding catalyst ASC1 may be an integrated unit comprising both SCR 1 and ASC1, or may be separate units for SCR 'and ASC1.
Correspondingly, the second reduction catalyst SCR2 and the second grinding catalyst ASC2 can either consist of an integrated unit comprising both SCR2 and ASC2, or can consist of separate units for SCR2 and ASC2.
According to an embodiment of the present invention, the exhaust gas treatment system 350 comprises a system 370 for supplying additives, which comprises at least one pump 373 arranged to supply the first 371 and second 372 dosing devices with additives, the viii saga with for instance ammonia or urea.
According to one embodiment, the system 370 provides at least one of the first 371 and second 372 dosing devices in liquid form additives.
Additives in liquid form can be refueled at many filling stations / gas stations where fuel is provided, so that the filling of the additive, and thus an optimized utilization of the two reduction steps in the exhaust gas treatment system can be ensured, where the optimized utilization can mean using both the first and second dosages. for dosing in different types of operation. The optimized utilization, for example, is then not limited to the fact that the first dosing device is only utilized during cold starts. Today, therefore, there is already an existing distribution network for liquid additives, which in turn ensures access to additives when the vehicle is driven.
In addition, vehicles only need to be supplemented with an additional dosing device, the first 371 dosing device, if only liquid additives are available for use. This minimizes the addition in complexity by using only liquid additives. If, for example, the gaseous additive is used, in addition to the liquid additive, the exhaust gas treatment system needs to be equipped with a complete system for supplying the gaseous additive. In addition, a distribution network and / or logistics for the supply of the gaseous additive need to be built up.
The secondary emission treatment system's secondary emissions of, for example, ammonia NH3 and / or hydrogen dioxide NO2 during normal operation of the combustion engine, that is to say not only in cold starts, can be reduced by using an embodiment of the present invention by dosing the additive in both the first 371 and other 372 dosing device. However, when using the embodiment, this implies that a substantially continuous dosage is possible to provide. Utilizing additives in liquid form means that the additive racks without interruption for service, since additives in liquid form can be bought at regular gas stations. As a result, substantially continuous dosing with both the first 371 and second 372 dosing devices can be done during the entire normal service intervals of a vehicle.
The possibility of continuous dosing with both the first 371 and second 372 dosing devices means that the exhaust gas treatment system can be utilized to its full potential. Thus, the system can be controlled so that robust and very high total degrees of NOx conversion can be obtained over time, without the system having to take height for the additive to run out. The factual availability of additives also means that a reliable control of the NO2 content NO2 / NOx can always be carried out, ie during the entire service intervals.
Utilizing additives in liquid form for dosing with both the first 371 and second 372 dosing devices allows the complexity of the system 370 to be maintained, since a common tank can be used for storing the additive. Additives in liquid form can be refueled at many filling stations / gas stations where fuel is provided, so that the filling of the additive, and thus an optimized utilization of the two reduction steps in the exhaust gas treatment system, can be ensured. According to another embodiment, the system 370 provides at least one of the first 371 and second 372 dosing devices in gaseous additives. According to one embodiment, this additive may be hydrogen gas H2.
An example of such an additive supply system 370 is shown schematically in Figure 3, where the system comprises the first metering device 371 and the second metering device 372, which are arranged upstream of the first reduction catalyst 331 and upstream of the second reduction catalyst 332. The first and second metering devices 371, 372, which are often dispensing nozzles that dispense additives into, and mix this additive with, the exhaust stream 303, additives are provided by the at least one pump 373 via additive lines 375. The at least one pump 373 receives the additive from one or more tanks 376 receives additive via one or more lines 377 between the tank (s) 376 and the at least one pump 373. It will be appreciated that the additive may be in liquid and / or gaseous form. as described above. DA the additive In liquid form Or the pump 373 is a liquid pump and the one or more tanks 376 are liquid containers. Then the additive Or in gaseous form Or the pump 373 a gas pump and the one or more tanks 376 Or gas containers. If both gaseous and liquid additives are used, several tanks and pumps are provided, at least one tank and pump Or being provided for supplying liquid additives and at least one tank and pump Or being arranged for providing gaseous additives.
According to one embodiment of the invention, the At least one pump 373 comprises a common pump which feeds both the first 371 and the second 372 dosing device with the first 48 and the second additive, respectively. According to another embodiment of the invention, the at least one pump comprises a first and a second pump, which feed the first 371 and the second 372 dosing device, respectively, with the first and second additives, respectively. The specific function of the additive system 370 is a choice described in the prior art, and the exact procedure for injecting additives is therefore not described in more detail. However, Alimant states that the temperature at the injection point / SCR catalyst should be above a lower limit value temperature in order to avoid precipitation and the formation of jokes. Undesirable by-products, such as ammonium nitrate NH4NO3. An example of a value for such a lower limit value temperature may be about 200 ° C. According to an embodiment of the invention, the system 370 for supply of additives comprises a dosing control unit 374 arranged to control the at least one pump 373, so that additives illfer the exhaust stream. According to one embodiment, the dosing control unit 374 comprises a first pump control unit 378 arranged to control the at least one pump 373, such that a first dosing of the first additive enters the exhaust stream 303 via the first dosing device 371. The dosing control unit 374 further comprises a second pump control unit. the at least one pump 373 on such that a second dose of the second additive is supplied to the exhaust stream 303 via the second metering device 372.
The first and second additives are usually the same type of additive, for example urea. However, according to one embodiment of the present invention, the first additive and the second additive may be of different types, for example urea and ammonia, causing the dosage to each of the first 331 and other 332 49 reduction catalyst devices, and thereby the function of each of the first 331 and second 332 reduction catalyst devices can be optimized above with respect to the type of additive. If different types of additives are used, the tank 376 comprises several sub-tanks, which contain the different respective types of additives. One or more pumps 373 may be used to provide all the different types of additives to the first dosing device 371 and the second dosing device 372. As mentioned above Or the one or more tanks and the one or more pumps adapted to the condition of the additive, the viii saga after am the additive Or gaseous or liquid.
The one or more pumps 373 are thus controlled by a dosing control unit 374, which generates control signals for controlling the supply of additives so that the desired amount is injected into the exhaust stream 303 by means of the first 371 and second 372 dosing devices upstream of the first 331 and second 332 reduction catalysts, respectively. In more detail, the first pump control unit 378 is arranged to control either a common pump, or a pump dedicated to the first dosing device 371, whereby the first dosing is controlled to be supplied to the exhaust stream 303 via the first dosing device 371. The second pump control unit 379 is arranged to control either a common pump, or a pump dedicated to the second metering device 372, whereby the second metering is controlled to be supplied to the exhaust stream 303 via the second metering device 372.
According to one aspect of the present invention, there is provided a method of treating an exhaust stream 303 emitted by an internal combustion engine 301. This method is described herein using Figure 4, in which the process steps follow the flow of the exhaust stream through the exhaust treatment system 350.
In a first step 401 of the process, the exhaust gas is supplied to a first additive by using a first metering device 371. In a second step 402 of the process, a reduction of nitrogen oxides NO in the exhaust stream is carried out by using this first additive in a first reduction catalyst device 331, which may include a first selective catalytic reduction catalyst SCR 'and / or a first grinding catalyst ASC1 and / or the SCRikmb described above, arranged downstream of the first dosing device 371. The first grinding catalyst ASC1 oxidizes has a residue of additives, where the residue may consist of, for example, urea , ammonia NH3 or isocyanic acid HNCO, and / or gives a further reduction of nitrogen oxides NO in the exhaust stream 303.
It should be noted that the reduction of nitrogen oxides NO by the first reduction catalyst device 331 in this document may include partial oxidation as long as the total reaction constitutes a reduction of nitrogen oxides NOR.
In a third step 403 of the process, the exhaust gas is filtered, soot particles being captured by a particulate filter 320 which at least partially comprises a catalytic oxidizing coating. This catalytic oxidizing coating oxidizes the trapped soot particles and one or more incompletely oxidized nitrogen and / or carbon compounds.
In a fourth step 404 of the process, a second additive is supplied to the exhaust stream 303 using a second metering device 372. In a fifth step 405 of the process, a reduction of the nitrogen oxides NO in the exhaust stream 303 is performed by using at least the second additive in a second reduction catalyst device 332. which may comprise 51 a second selective catalytic reduction catalyst SCR2 and in some configurations a second grinding catalyst ASC2, arranged downstream of the second metering device 371. The second grinding catalyst oxidizes has an excess of ammonia and / or gives a further reduction of nitrogen oxides NO in the exhaust stream 303 It should be noted that the reduction of nitrogen oxides NO by the second reduction catalyst device 332 in this document may include partial oxidation as long as the total reaction represents a reduction of nitrogen oxides NOR.
It can be seen that a first temperature Ti to which the first reduction catalyst device 331 is exposed and a second temperature 12 to which the second reduction catalyst device 332 is exposed are of great importance to the operation of the exhaust gas treatment system 350. However, it is difficult to regulate these temperatures 11, T2, since they largely depend on how the driver in front of the vehicle, it viii say that the first T1 and second T2 temperatures depend on the actual operation of the vehicle and on input via, for example, an accelerator pedal in the vehicle.
The exhaust gas treatment process and the exhaust gas treatment system 350 itself become considerably more efficient in a traditional system (as shown in Figure 2) in that the first temperature Ti for the first reduction catalyst device 331, for example at start-up processes, previously reaches the value of the first temperature T1, and thereby higher efficiency in the reduction of nitrogen oxides NO by the process of the present invention. Alltsa erhalls has a more effective reduction of nitrogen oxides NOR, for example at cold starts and at paddles from low exhaust temperatures, which results in less increase in fuel consumption in such choruses. In other words, the present invention utilizes the response-controlled first Ti and 52 other 12 temperatures to its advantage in such a way that they contribute to increasing the overall efficiency of the exhaust gas purification system.
The advantages of the exhaust gas treatment system 350 mentioned above are also obtained for the process of the present invention.
According to one embodiment of the process of the present invention, the reduction is controlled by the first reduction catalyst device 331 to occur at a reduction temperature range, which is at least partially different from an oxidation temperature range of Tox, which a significant sotoxidation in the particulate filter 320 occurs. in the first reduction catalyst device does not significantly compete with the nitrogen dioxide-based sotoxidation in the particle filter cDPF.
According to an embodiment of the method according to the present invention, the supply of additives to the first dosing device 371 and / or the second dosing device 372 is increased to a level of added additive at which residues / precipitates / crystallization can occur. This level can be determined, for example, by comparison with a predetermined threshold value for the supply. Utilization of this embodiment can thus result in residues / precipitates / crystals of additives being created.
According to an embodiment of the method according to the present invention, the supply of additives to the first dosing device 371 and / or to the second dosing device 372 is reduced when precipitates / residues of the additive have formed, whereby these precipitates can be eliminated. The reduction can therefore mean that the supply is completely interrupted. As a result, for example, a larger dosage in the first dosing position of the first reduction catalyst device can be allowed, since any precipitates / residues can naturally be heated away at the same time as the emission requirements are met by the second reduction catalyst device in the meantime.
The reduction / interruption of the supply may be due to current and / or predicted operating conditions of the internal combustion engine and / or the exhaust gas treatment system. Thus, for example, the second reduction catalyst device 332 must not be designed to handle a shut-off of the supply by means of the first dosing device 371 for all operating cases. An intelligent control requires a smaller system which can be used when appropriate and when this system can provide a required catalytic function.
According to one embodiment of the process, the first reduction catalyst device 371 is optimized based on properties, such as catalytic properties, for the first 371 and / or second 372 reduction catalyst device. In addition, the second reduction catalyst device 372 can also be optimized based on properties, such as catalytic properties, for the first 371 and / or second 372 reduction catalyst device. These possibilities for optimizing the first reduction catalyst device and / or the second reduction catalyst device provide an overall efficient exhaust gas purification which better takes into account the hazards of the complete exhaust gas treatment system.
The above-mentioned properties of the first 371 and / or second 372 reduction catalyst device may be related to one or more of the catalytic properties of the first 371 and / or other 372 reduction catalyst device, a catalyst type of the first 371 and / or other 372 54 reduction catalyst device, a temperature range at which the first 371 and / or second 372 reduction catalyst device is active and a degree of ammonia filling for the first 371 and / or second 372 reduction catalyst device 372.
According to one embodiment of the present invention, the first reduction catalyst device 371 and the second reduction catalyst device 372, respectively, are optimized based on the operating conditions of the first 371 and second 372 reduction catalyst devices, respectively. These operating conditions may be related to a temperature, i.e. a static temperature, for the first 371 and the second 372 reduction catalyst device, respectively, and / or to a temperature trend, i.e. a change in temperature, for the first 371 and the second 372 reduction catalyst device, respectively.
According to one embodiment of the process of the present invention, an active control of the reduction challenge is performed by the first reduction catalyst device 331 based on a ratio between the amount of nitrogen dioxide NO2SCR2 and the amount of nitrogen oxides NOx SCR2 driving the second reduction catalyst device 332. In other words, NOx SC22 to have a suitable value for the reduction in the second reduction catalyst device 332, whereby a more effective reduction can be obtained. In more detail, therefore, the first reduction catalyst device 331 has a first reduction of a first amount of nitrogen oxides NOx scRa which reaches the first reduction catalyst device 331. At the second reduction catalyst device 332, a second reduction of a second amount of nitrogen oxides is performed. , where an adjustment is made of the ratio NO2 SCR2 / NOx SCR2 between the amount of nitrogen dioxide NO2scR2 and the second amount of nitrogen oxides NOxscR2 which reach the second reduction catalyst device 332.
This adjustment is carried out by utilizing an active control of the first reduction based on a value for driving NO2scR2 / NO.scR2, with the intention of giving the driving NO2 SCR2 / NOx SCR2 a value which makes the second reduction more efficient. The value for the ratio NO2 SCR2 / NOx SCR2 may have consisted of a measured value, a modeled value and / or a predicted value.
Those skilled in the art will appreciate that a method of processing an exhaust stream according to the present invention may additionally be implemented in a computer program, which when executed in a computer causes the computer to perform the procedure. The computer program usually forms part of a computer program product 503, wherein the computer program product comprises a suitable digital non-volatile / durable / permanent / permanent storage medium on which the computer program is stored. The said computer-readable non-volatile / durable / durable / permanent medium consists of a readable memory, such as: ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable PROM), Flash memory, EEPROM (Electrically Erasable PROM), a hard disk drive, etc.
Figure 5 schematically shows a control unit 500. The control unit 500 comprises a computing unit 501, which can be constituted by essentially any suitable type of processor or microcomputer, e.g. a Digital Signal Processor (DSP), or an Application Specific Integrated Circuit (ASIC).
The calculating unit 501 is connected to a memory unit 502 arranged in the control unit 500, which provides the calculating unit 501, e.g. the stored program code and / or the stored data calculation unit 501 need to be able to perform calculations. The calculating unit 501 is also arranged to store partial or final results of calculations in the memory unit 502.
Furthermore, the control unit 500 is provided with devices 511, 512, 513, 514 for receiving and transmitting input and output signals, respectively. These input and output signals may contain waveforms, pulses, or other attributes, which of the input signals receiving devices 511, 513 may be detected as information and may be converted into signals which may be processed by the calculating unit 501. These signals are then provided to the calculating unit 501. The devices 512 , 514 for transmitting output signals Or arranged to convert coverage results from the recovery unit 501 into output signals for transmission to other parts of the vehicle control system and / or the component (s) for which the signals Or are intended.
Each of the connections to the devices for receiving and transmitting input and output signals, respectively, may be constituted by one or more of a cable; a data bus, such as a CAN bus (Controller Area Network bus), a MOST bus (Media Orientated Systems Transport bus), or any other bus configuration; or by a wireless connection.
One skilled in the art will appreciate that the above-mentioned computer may be constituted by the storage unit 501 and that the above-mentioned memory may be constituted by the memory unit 502.
General control systems in modern vehicles consist of a communication bus system consisting of one or more communication buses for interconnecting a number of electronic control units (ECUs), or controllers, and various components located in the vehicle. Such a control system may comprise a large number of control units, and the responsibility for a specific function may be divided into more than one control unit. Vehicles of the type shown thus often comprise considerably more control units than what is shown in Figure 5, which is a choice for those skilled in the art.
As will be appreciated by those skilled in the art, the control unit 500 of Figure 5 may include one or more of the control units 115 and 160 of Figure 1, the control unit 260 of Figure 2, the control unit 360 of Figure 3 and the control unit 374 of Figure 3.
In the embodiment shown, the present invention is implemented in the control unit 500. However, the invention can also be implemented in whole or in part in one or more other control units already existing at the vehicle or in a control unit dedicated to the present invention.
Those skilled in the art will also appreciate that the above exhaust gas treatment system may be modified according to the various embodiments of the method of the invention. In addition, the invention relates to the motor vehicle 100, for example a passenger car, a truck or a bus, or another unit comprising at least one exhaust gas treatment system according to the invention, such as for example a vehicle or a voltage / tension generator.
The present invention is not limited to the above-described embodiments of the invention but relates to and includes all embodiments within the scope of the appended independent claims. 58

权利要求:
Claims (28)
[1]
An exhaust treatment system (350) arranged for treating an exhaust stream (303) resulting from a combustion in an internal combustion engine (301), characterized by - a first dosing device (371) arranged to supply a first additive in said exhaust stream (303). ); A first reduction catalyst device (331) disposed downstream of said first metering device (371) and arranged to reduce nitrogen oxides NO in said exhaust stream (303) by utilizing said first additive; A particulate filter (320) at least partially comprising a catalytically oxidizing coating, which Or is arranged downstream of said first reduction catalyst device (331) and Or is arranged to capture and oxidize soot particles and to oxidize one or more of nitric oxide NO and incompletely oxidized carbon compounds of nO (303); A second dosing device (372) arranged downstream of said particle filter (320) and arranged to supply a second additive in said exhaust stream (303); and - a second reduction catalyst device (332) arranged downstream of said second dosing device (372) and arranged to reduce nitrogen oxides NO in said exhaust stream (303) by using at least one of said first and said second additives.
[2]
An exhaust gas treatment system (350) according to claim 1, wherein at least one of said first and second additives comprises ammonia or a substance from which ammonia can be recovered and / or released.
[3]
An exhaust gas treatment system (350) according to any one of claims 1-2, wherein said first reduction catalyst device (331) comprises any one in the group of: 1. a first selective catalytic reduction catalyst (SCR); 2. a first selective catalytic reduction catalyst (SCR) downstream integrated with a first slip catalyst (ASC1), wherein said first slip catalyst (ASC1) is arranged to oxidize a residue of additives and / or to assist said first selective catalytic reduction catalyst (ASC1); SCR ') with a further reduction of nitrogen oxides NO in said exhaust stream (303); a first selective catalytic reduction catalyst (SCR) downstream followed by a separate first slip catalyst (ASC1), wherein said first slip catalyst (ASC1) is arranged to oxidize a residue of additives and / or to assist said first selective catalytic reduction catalyst (ASC1); SCR) with a further reduction of nitrogen oxides NO in said exhaust gas stream (303); A first slip catalyst (ASC1), which is arranged first for reduction of nitrogen oxides NO and secondarily for oxidation of a residue of additives in said exhaust gas stream (303); and 4. a first selective catalytic reduction catalyst (SCR) combined with a pure oxidizing coating in its outlet portion.
[4]
An exhaust gas treatment system (350) according to any one of claims 1-3, wherein said second reduction catalyst device (332) comprises any one of the group of: 1. a second selective catalytic reduction catalyst (SCRJ; 2. a second selective catalytic reduction catalyst (SCRJ downstream integrated with a second grinding catalyst (ASCJ), wherein said second grinding catalyst (ASC2) is arranged to oxidize a residue of additives and / or to assist said second selective catalytic reduction catalyst (SCR2) with a further reduction of nitrogen oxides NO in said exhaust stream (303 and - a second selective catalytic reduction catalyst (SCR2) is de-energized followed by a separate second grinding catalyst (ASC2), wherein said second grinding catalyst (ASC2) is arranged to oxidize a residue of additives and / or to bite said second selective catalytic reduction catalyst (SCR2) with a further reduction of nitrogen oxides NO in said exhaust gas stream (303).
[5]
An exhaust gas treatment system (350) according to any one of claims 1 to 4, wherein said particulate filter (320) is the first exhaust gas treatment system component said exhaust gas stream (303) after passing said first reduction catalyst device (331).
[6]
An exhaust gas treatment system (350) according to any one of claims 1-5, wherein said exhaust gas treatment system (350) comprises a system (370) for supplying additives, which comprises at least one pump (373) arranged to supply said first (371) and others (371). 372) dosing device with said first and second additives, respectively.
[7]
The exhaust gas treatment system (350) of claim 6, wherein said additive supply system (370) comprises a metering control unit (374) arranged to control said at least one pump (373).
[8]
An exhaust gas treatment system (350) according to claim 6, wherein said additive supply system (370) comprises a metering control unit (374) comprising: - a first pump control unit (378) arranged to control said at least one pump (373), wherein a first metering of said first additive, said exhaust gas is supplied by 61 using said first metering device (371); and - a second pump control unit (379) arranged to control said at least one pump (373), a second metering of said second additive being supplied to said exhaust stream by utilizing said second metering device (372).
[9]
An exhaust gas treatment system according to any one of claims 1 to 8, wherein said first reduction catalyst device (331) is arranged to reduce said nitrogen oxides NO at a reduction temperature range, which is at least partially different from an oxidation temperature range of Lox at which said particulate filter (320). for oxidation of incompletely oxidized carbon compounds; 'redTox.
[10]
An exhaust gas treatment system according to any one of claims 1-9, wherein said first reduction catalyst device (331) constitutes an at least partially protective substrate upstream of a catalytically oxidizing coating.
[11]
A method of treating an exhaust stream (303) which results from a combustion in an internal combustion engine (301), characterized by - a control of a supply of a first additive in said exhaust stream by using a first dosing device (371), wherein said supply of said first additive effects a reduction of nitrogen oxides NO in said exhaust stream by utilizing said first additive in at least one first reduction catalyst device (331) arranged downstream of said first metering device (371); and - capturing and oxidizing soot particles and oxidizing one or more of nitrous oxide NO and incompletely oxidized carbon compounds in said exhaust stream (303) by utilizing a particulate filter (320) at least partially 62 comprising a catalytic oxidizing coating disposed downstream of said first reduction catalyst device (331); and - controlling the supply of a second additive in said exhaust stream (303) by using a second dosing device (372) arranged downstream of said particle filter (320), said supply of said second additive affecting a reduction of nitrogen oxides NO in said exhaust stream ( 303) by utilizing at least one of said first and said second additives in a second reduction catalyst device (332) arranged downstream of said second dosing device (372).
[12]
The method of claim 11, wherein said combustion engine (301) is controlled to generate heat for heating said first reduction catalyst device (331) to such an extent that said first reduction catalyst device (331) reaches a predetermined temperature.
[13]
A process according to any one of claims 11 to 12, wherein said reduction by means of said first reduction catalyst device (331) is controlled to occur at a reduction temperature range TrAd, which is at least partially different from an oxidation temperature range T, wherein said oxidation of incompletely oxidized carbon compounds by (320) happens; Tr, d
[14]
A method according to any one of claims 11-13, wherein said supply of at least one of said first and second additives by utilizing one of said first dosing device (371) and said second dosing device (372) is increased to a level at which there is a risk for precipitations of the said additive to occur. 63
[15]
The process of claim 14, wherein said first reduction catalyst device (331) comprises a first grinding catalyst (ASC1), which primarily performs reduction of nitrogen oxides NO and secondarily performs oxidation of a residue of additives in said exhaust gas stream (303). .
[16]
A method according to any one of claims 11-13, wherein said supply of at least one of said first and second additives by using one of said first dosing device (371) and said second dosing device (372), respectively, is reduced, after which residues of at least one of said first and second additives are eliminated by heat of said exhaust stream, where said reduction of said supply is carried out if necessary total catalytic function of an exhaust gas treatment system (350) which for said process can be provided after said decreasing.
[17]
The method of claim 16, wherein said required catalytic function depends on current and / or predicted operating conditions for said internal combustion engine (301).
[18]
A method according to any one of claims 16-17, wherein said reduction of said supply constitutes an interruption of said supply.
[19]
A method according to any of claims 11-18, wherein said effect on said reduction of nitrogen oxides NO for said first reduction catalyst device (371) is controlled based on one or more properties and / or operating conditions of said first reduction catalyst device (371). 64
[20]
A method according to any one of claims 11-18, wherein said effect on said reduction of nitrogen oxides NO for said first reduction catalyst device (371) is controlled based on one or more properties and / or operating conditions of said second reduction catalyst device (372).
[21]
A method according to any one of claims 11-18, wherein said effect on said second reduction catalyst device (372) is controlled based on one or more properties and / or operating conditions of said second reduction catalyst device (372).
[22]
A method according to any one of claims 11-18, wherein said effect on said second reduction catalyst device (372) is controlled based on one or more properties and / or operating conditions of said first reduction catalyst device (371).
[23]
A process according to any one of claims 19-22, wherein said properties of said first (371) and second (372) reduction catalyst devices are related to one or more of the group of: 1. catalytic properties of said first reduction catalyst device (371); 2. catalytic properties of said second reduction catalyst device (372); a type of catalyst for said first reduction catalyst device (371); 3. a catalyst type for said second reduction catalyst device (372); A temperature range in which said first reduction catalyst device (371) is active; A temperature range in which said second reduction catalyst device (372) is active; 6. a degree of ammonia filling for said first reduction catalyst device (371); and 7. a degree of ammonia filling for said second reduction catalyst device (372).
[24]
A process according to any one of claims 11 to 23, wherein said first reduction catalyst device (331) is a substrate which at least partially protects a catalytic oxidizing coating.
[25]
A process according to any one of claims 11-24, wherein 1. said first reduction catalyst device (331) performs a first reduction of a first amount of said nitrogen oxides NOx scRi which reaches said first reduction catalyst device (331); - said second reduction catalyst device (332) performs a second reduction of a second amount of said nitrogen oxides NOx scR2 which reaches said second reduction catalyst device (332); and 2. an adaptation is performed of a ratio NO2 2C22 / NOx SCR2 between an amount of nitrogen dioxide NO2 scR2 and said second amount of nitrogen oxides NOx scR2 which are said second reduction catalyst device (332), an active control of said first reduction of said first amount of nitrogen oxides NO scRi is performed based on a value for the said ratio NO2 SCR2 / NOx SCR2 •
[26]
The method of claim 25, wherein said value is said ratio NO2scR2 / NOx SCR2 is one of the group of: 1. a measured value; 2. a modeled value; - a predicted value. 66
[27]
A computer program comprising program code, which when said program code is executed in a computer causes said computer to perform the procedure according to any of claims 11-26.
[28]
A computer program product comprising a computer readable medium and a computer program according to claim 27, wherein said computer program is included in said computer readable medium. 91. 901. "- '1. 01. LOI. 901. 91. 901. ---' LO £ 01. 1701. ---- # £ 1. r4 I- 'Old 2/2 201 00000 203 12 - 11.0DP F 261 202 260

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