DE112012003226T5 - Exhaust treatment system with hydrocarbon lean NOx catalyst - Google Patents

Abstract

A system for treating an exhaust gas stream from an internal combustion engine includes a main exhaust passageway adapted to receive the exhaust gas flow from the internal combustion engine. A side branch communicates with the main exhaust duct. A regeneration unit for burning a fuel and heating the exhaust gas flowing through the main exhaust passage is arranged in the side branch. A lean NO _x catalyst is located downstream of the regeneration unit in the main exhaust duct. A reducing agent injection means is disposed downstream _x catalyst from the regeneration unit and upstream of the Lean-NO to inject reducing agent particles in the exhaust stream. A control unit controls the regeneration unit to increase the exhaust temperature, and controls the reducing agent injector to reduce _NOx in the lean _NOx catalyst.

Description

FIELD OF THE INVENTION

The present invention relates generally to a system for treating exhaust gases. In particular, a device for increasing an exhaust gas temperature upstream discussed from a hydrocarbon-lean _NOx catalyst

BACKGROUND

In an attempt to reduce the amount of NO _x and particulate matter emitted to the atmosphere during engine operation, a number of exhaust aftertreatment devices have been developed. Exhaust aftertreatment systems are particularly required when diesel combustion processes take place. Typical diesel engine after-treatment systems may include one or more of a diesel particulate filter (DPF), a selective catalytic reduction (SCR) system, a hydrocarbon (HC) injector, and a diesel oxidation catalyst (DOC).

During engine operation, the DPF absorbs soot emitted by the engine and lowers the emission of particulate matter (PM). Over time, the DPF becomes laden and begins to clog. For proper operation, therefore, periodic regeneration or oxidation of the absorbed soot in the DPF is required. In order to regenerate the DPF, relatively high exhaust gas temperatures are required in combination with a sufficient amount of oxygen in the exhaust stream to oxidize the soot absorbed in the filter.

The DOC is typically used to generate heat to regenerate the carbon black loaded DPF. When hydrocarbons (HC) are sprayed onto the DOC at or above a certain light-off temperature, the HCs are oxidized. This reaction is highly exothermic and the exhaust gases are heated during the light-off process. The heated exhaust gases are used to regenerate the DPF.

However, under many engine operating conditions, the exhaust gas is not hot enough to reach a DOC light-off temperature of about 300 ° C. Therefore, DPF regeneration is not passive. Additionally, NO _x adsorbers and selective catalytic reduction systems typically require a minimum exhaust gas temperature for proper operation.

A burner may be provided to heat the exhaust stream upstream of the various aftertreatment devices. Known burners have successfully increased the exhaust gas temperature of internal combustion engines for motor vehicles. Some OEMs have resisted the use of conventional burners due to their size and cost. Further, in other applications such as diesel locomotives, stationary power plants, ships, and the like, relatively large diesel compression engines may be provided. The exhaust mass flow rate of larger internal combustion engines may be more than ten times the maximum throughput typically provided to the combustor. Although it is possible to increase the size of the burner to account for the increased exhaust mass flow rate, the concessions associated with this solution may be unacceptable in terms of cost, weight, and installation space. Therefore, there is in the art a need for an exhaust gas treatment system comprising a hydrocarbon-lean _NOx catalyst and a device for increasing the temperature of the output of an internal combustion engine exhaust gas, while the cost, weight, size, and the performance of the exhaust system only minimal to be influenced. It may also be desirable to minimize the pressure drop and / or back pressure associated with the use of a burner.

BRIEF DESCRIPTION OF THE INVENTION

This section contains a general summary of the invention and is not intended to be exhaustive of its full scope or all features.

A system for treating an exhaust gas stream from an internal combustion engine includes a main exhaust passageway adapted to receive the exhaust gas flow from the internal combustion engine. A side branch communicates with the main exhaust duct. A regeneration unit for burning a fuel and heating the exhaust gas flowing through the main exhaust passage is arranged in the side branch. A lean NO _x catalyst is located downstream of the regeneration unit in the main exhaust duct. A reducing agent injection means for injecting reducing agent particles in the exhaust gas flow is arranged downstream of the regeneration unit and upstream of the lean _NOx catalyst. A control unit controls the regeneration unit to increase the exhaust temperature, and controls the reducing agent injector to reduce _NOx in the lean _NOx catalyst.

A system for treating an exhaust stream from an internal combustion engine includes a burner for burning a fuel and for heating the fuel flowing through an exhaust passage Exhaust gas on. A lean NO _x catalyst is located downstream of the burner in the exhaust passage. A reducing agent injection means for injecting reducing agent particles in the exhaust gas stream is located upstream from the burner and upstream of the lean _NOx catalyst. A control unit controls the burner to increase the exhaust temperature, and controls the injector to reduce _NOx in the lean _NOx catalyst.

A system for treating an exhaust stream from an internal combustion engine includes a burner for burning a fuel and for heating the exhaust gas flowing through an exhaust passage. A lean NO _x catalyst is disposed in the exhaust passage and directly receives the exhaust gas heated by the burner before passing through another catalyst. A hydrocarbon injection means for injecting hydrocarbon into the exhaust gas stream is located downstream from the burner and upstream of the lean _NOx catalyst. A control unit controls the burner to increase the exhaust temperature to a predetermined value for the combustion of carbon deposits, which are arranged at the active sites within the lean _NOx catalyst.

Further fields of application will be apparent from the present description. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are merely illustrative of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present invention.

1 shows a schematic representation of a system for controlling the temperature of an exhaust gas from an internal combustion engine;

2 shows a side cross-sectional view of a part of the in 1 illustrated exhaust aftertreatment system with a miniature regeneration unit;

3 shows a cross-sectional view of another regeneration unit;

4 shows a cross-sectional view of another regeneration unit;

5 shows a cross-sectional view of an engine exhaust aftertreatment system with a Stromumlenkeinrichtung;

6 shows a perspective view of the aftertreatment system with the Stromumlenkeinrichtung;

7 shows a partial perspective view of part of another regeneration unit;

8th shows a cross-sectional view of another regeneration unit;

9 - 13 show perspective views for illustrating other inlet pipe sections of the regeneration unit;

14 shows a cross-sectional view for illustrating another exhaust aftertreatment system;

15 - 19 show other exhaust aftertreatment systems with a regeneration unit and a hydrocarbon lean NO _x catalyst; and

20 and 21 show other exhaust aftertreatment systems with a burner and a hydrocarbon lean NO _x catalyst.

Corresponding reference numerals designate corresponding parts in the several views of the drawings.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, exemplary embodiments will be described with reference to the accompanying drawings.

1 shows an exhaust aftertreatment system 10 for treating by an exemplary internal combustion engine 12 to a main exhaust duct 14 output exhaust gas. An inlet channel 16 is with the internal combustion engine 12 connected to it to supply combustion air. A turbocharger 18 has a driven element (not shown) arranged in an exhaust gas flow. During engine operation, the exhaust flow causes rotational movement of the driven element, thereby increasing the intake passage 16 compressed air is supplied before entering the internal combustion engine 12 entry.

The exhaust aftertreatment system 10 also has a downstream of the turbocharger 18 and upstream of a plurality of exhaust after-treatment devices Miniature regeneration unit 26 on. In the in 1 As shown in the exemplary after-treatment system, the aftertreatment devices have a hydrocarbon injector 28 , a diesel oxidation catalyst 30 and a diesel particulate filter 32 on.

The regeneration unit 26 is in a side branch section 34 of the system 10 in communication with the main exhaust duct 14 arranged. The regeneration unit 26 can be used to warm the channel 14 flowing through exhaust gas can be used at an elevated temperature, which increases the efficiency of the DOC 30 improve and regeneration of the DPF 32 will allow.

The regeneration unit 26 can be one or more injectors 36 for injecting a suitable fuel and an oxygenating agent. The fuel may be hydrogen or a hydrocarbon. The injector 36 may be structured as a combined injector that injects both the fuel and the oxygenating agent, as in FIG 1 or may have separate injectors for the fuel and the oxygenating agent ( 11 ). A control module 38 is for monitoring and controlling the flow rates through the injector 36 and the ignition of the fuel by a first ignition device 42 using a suitable processor (s), sensors, flow control valves, electrical coils, etc.

The regeneration unit 26 has a housing 50 on, which is constructed as a multi-part assembly of prefabricated metal components. The housing 50 has an inlet tube 52 , a cylindrical body 54 and an outlet pipe 56 on. An inlet head 58 is at the inlet pipe 52 attached. The inlet head 58 is at a side branch section 34 attached and enclosing one of its ends. Within the scope of the present invention, other single or multi-part inlet arrangements are contemplated. An annular volume 62 is within a space between an inner surface 64 of the side branch section 34 and an outer surface of the housing 50 educated.

An injector holder 65 is at the inlet pipe 52 and / or at the inlet head 58 attached to a mounting mechanism for the injector 36 provide. A nozzle section 66 the injection device 36 extends into the inlet pipe 52 , allowing atomized fuel into a primary combustion chamber 68 can be injected, at least partially through an inner cylinder surface 70 of the body 54 is defined. The injector 36 has a fuel inlet 72 and an air inlet 74 on. The fuel inlet 72 communicates with a fuel supply system 76 holding a fuel tank 78 , a fuel filter 80 , a fuel pump 82 and a fuel block 84 that passes through a fuel line 86 connected to each other. By operating the components of the fuel supply system 76 becomes the injector 36 selectively fed to hydrocarbon.

A secondary air system 90 has a secondary air filter 92 and a MAF sensor 94 on. A compressor 96 receives air, which is the secondary air filter 92 and the MAF sensor 94 flowed through. The compressor 96 may comprise a part of a supercharger, a turbocharger or a stand-alone electric compressor. The outlet flow of the compressor 96 gets the air intake 74 fed. When exhaust warming is desired, fuel is delivered via the fuel inlet 72 injected and the oxygenating agent through the air inlet 74 provided to inject a stream of atomized fuel. The first ignition device 42 is at the side branch section 34 downstream from the inlet head 58 mounted and operable by the injector 36 provided fuel within the primary combustion chamber 68 to burn.

The side branch section 34 meets at an angle A of substantially 30 Degree on the exhaust duct 14 , The through the regeneration unit 26 generated flame extends at substantially the same angle in the exhaust passage 14 ,

An elongated opening 110 extends through a main exhaust duct 14 defining pipe 112 , Part of the body 54 and the outlet tube 56 are inside the exhaust duct 14 arranged. From the internal combustion engine 12 escaping exhaust gas hits the housing 50 and cools it during operation of the regeneration unit 26 from. It also takes off because of the case 50 Only minimal in the channel 14 extends, the exhaust back pressure also only minimal. It should also be clear that the side branch section 34 and the injector 36 from the pipe 112 extend radially to the outside. Such an arrangement allows an OEM to more easily house the miniature regeneration unit in the vehicle.

In the present aftertreatment system, the first ignition device 42 also one with the coil 46 connected ion sensor 44 exhibit. The ion sensor 44 can take the form of one inside the combustion chamber 68 arranged electrode. To the ion sensor, a voltage for generating an electric field from the sensor to a mass, such as casing 50 to be created. When a voltage is applied, an electric field is generated by the sensor to ground. If there are free ions in the field, a small ion current can flow. The size of the ionic current is an indication of the density of the ions. A control module 38 detects and receives signals from the ion sensor 44 to determine the presence or absence of a flame. The ion sensor 44 can also determine if the ignition device 42 is dirty.

Contamination can occur due to buildup of soot, oil or other contaminants. When the ignition device 42 polluted, no suitable combustion can take place. The control module 38 is operable to the fuel inlet 72 Fuel, the air intake 74 Air and the ignition device 42 to supply electrical energy and to interrupt the supply of fuel, air and energy. Before the injector 36 Fuel and air is supplied determines the control module 38 by means of the ion sensor 44 provided signal, whether the ignition device 42 is dirty. If it is determined that the ignition device is ready, the control module 38 a plurality of engine and vehicle operating parameters, such as engine speed, ambient temperature, vehicle speed, engine coolant temperature, oxygen content, air mass flow rate, pressure differential across the diesel particulate filter 32 and consider any number of other vehicle parameters. If the control module 38 determines that an increase in the exhaust gas temperature is desired, the injector 36 Fuel and secondary air supplied. The sink 46 leads the ignition device 42 electrical energy to cause combustion within the primary combustion chamber 68 trigger.

The control module 38 may also include a number of other parameters, such as the presence of combustion and the temperature of the exhaust gas within the duct 14 at a location downstream of the regeneration unit 26 Evaluate to determine when the fuel and air to the injector 36 should be terminated. For example, the control module 38 Receive signals from one or more temperature sensors in the regeneration unit 26 , in the side branch section 34 or in the main channel 14 are arranged to operate by the regeneration unit 26 to perform closed-loop control to maintain a desired temperature at a particular location. If combustion unexpectedly goes off, the control module stops 38 the fuel supply. Within the scope of the present invention, other control methods are also contemplated.

3 shows one with the side branch section 34 connected other regeneration unit 26a , The regeneration unit 26a is the regeneration unit 26 substantially similar except that the outlet tube section is of reduced diameter or narrowed mouth of the housing 50 has been removed. Therefore, similar elements are designated by an addition "a". The main body section 54a has a substantially constant diameter at an outlet opening 53a ends.

4 shows a by the reference numeral 26b designated other regeneration unit. The regeneration unit 26b is the regeneration unit 26 is substantially similar except that a length L has been increased to cause a larger portion of the housing 50b inside the exhaust duct 14 is arranged. Similar elements are designated by an addition "b". The position of the ignition device 42b has been changed so that it is farther from one end of the nozzle 66 is removed.

The 5 and 6 show another arrangement with a baffle 140 located upstream of the miniature regeneration unit 26 in the pipe 112 is arranged. The baffle plate 140 has a D-shaped opening extending therethrough 142 on. The baffle plate 140 is arranged at an angle, as in 5 is shown to pass through the channel 14 forcing flowing exhaust gas to the housing 50 to flow around and around the case. The redirected exhaust gas flow transfers heat from the regeneration unit 26 on the through the pipe 112 flowing exhaust gas.

7 shows a part of one by the reference numeral 26c designated other regeneration unit. The regeneration unit 26c is the regeneration unit 26 essentially similar, except that the length of the outlet tube 56c is enlarged and the outlet pipe a plurality of openings extending through the outlet pipe 144 having. The larger outlet tube length and the openings 144 Make sure that the combustion flame during operation of the regeneration unit 26c is maintained properly and remains aligned. If exhaust through the channel 14 flows, a portion of the exhaust gas flows through the openings 144 whereby a mixing effect is produced, which leads to a more favorable temperature distribution, flame stability and flame quality.

8th shows a by the reference numeral 26d designated other regeneration unit. The regeneration unit 26d has the components of the regeneration unit 26 and an additional housing section 145 on top of a secondary combustion chamber 146 Are defined. A second ignition device 148 extends into the secondary combustion chamber 146 , Several openings 149 extend through the second housing 145 to allow exhaust gas into the secondary combustion chamber 146 can occur. By using the regeneration unit 26d Better exhaust gas heating and mixing can be achieved.

The 9 - 13 show other inlet tube configurations that replace the inlet tube 52 can be used. Each of the modified inlet tubes has a plurality of circumferentially spaced openings 150 on, extending through an end wall 152 extend. The openings 150 allow that to be the channel 14 flowing exhaust gas into the primary combustion chamber 68 can occur. By feeding oxygen into the primary combustion chamber 68 over the openings 150 can the pressure of the injector 36 from the compressor 96 supplied secondary air can be reduced. The cost and size of the compressor 96 can also be reduced.

This in 9 illustrated inlet pipe 52e has several at one end to an end wall 152e attached tabs 156e on. The tabs 156e are designed to swirl the openings 150e to cause flowing gas. 10 shows rectangular openings 150f without straps. 11 shows several on a radially inner side of the openings 150g attached tabs 156g , The tabs 156g extend radially outward at an angle to the exhaust stream. 12 shows another inlet tube assembly 52h with several openings 150h and several tabs 156h , The tabs 156h extend radially inward.

13 shows a plurality of circumferentially spaced apart circular openings 150i , The openings are not partially blocked by tabs. Through each of the in the 9 - 13 arrangements shown is a substantially homogeneous flow distribution in the interior of the primary combustion chamber 68 provided.

It is also contemplated that any of the described miniature regeneration unit assemblies having openings 150 an injection device 36j with a staggered secondary air intake 74j for injecting compressed air at a relatively low pressure into an annular volume 62 may have, as in 14 is shown. A fuel inlet 72j is arranged such that atomized fuel into the primary combustion chamber 68j is injected as discussed above. Part of the in the annular volume 62j injected air flows through the openings 150i and the remainder of the secondary air flows along an outer surface of the housing 50j to the miniature regeneration unit 26j to cool.

15 shows a portion of one by the reference numeral 200 designated other exhaust aftertreatment system. The system 200 is in the 1 illustrated system 10 similar. Therefore, similar elements retain their previously introduced reference numerals. The exhaust aftertreatment system 200 has one immediately downstream of the DPF 32 arranged reducing agent injector 202 on. The reductant injector may act as an aerosol generator 202 be configured. The reducing agent injector 202 becomes a hydrocarbon, such as in the fuel tank 78 stored diesel fuel fed. In the in 15 As illustrated, the reductant injector becomes fuel from the fuel tank 78 over a fuel line 204 fed. Other engine fuels, such as ethanol-based fuels, such as E85, E93 or E95, may be the reductant of choice and stored in a separate on-board vessel.

The aerosol generator 202 has an electrically operated heating element. The over the fuel line 204 supplied reducing agent is heated by the heating element. It should be noted that the reducing agent may or may not come into direct contact with a surface of the heating element. Regardless of the configuration, energy is transferred from the heating element to the reducing agent to increase the temperature and energy content of the reducing agent. The heated reductant becomes downstream of the DPF 32 injected into the exhaust stream. Based on the nozzle design, reductant pressure, and reductant temperature, very small reductant droplets less than one micron in size are introduced into the exhaust passage 14 injected.

A lean _NOx catalyst (LNC) 208 and a selective catalytic reduction device (SCR) 210 are in a common housing 214 assembled. The LNC 208 is upstream of the SCR 210 positioned to reduce NO _x in an oxygen-rich environment. The LNC 208 is a hydrocarbon-lean _NOx catalyst, which is configured to reduce _NOx using a hydrocarbon as the reducing agent. The aerosol generator 202 offers many design advantages for the exhaust aftertreatment system 200 , The one from the aerosol generator 202 exiting heated aerosol mist of the reducing agent is in the from the DPF 32 Exiting exhaust quickly distributed. Only a minimum exhaust conduit length is required to provide a mixing zone for the exhaust gas and reductant before entering the LNC 208 provide. The small Reductant droplets interact with the porous surface of the LNC 208 more efficient than larger reductant droplets. The use of the aerosol generator 202 results in improved catalyst response of the LNC 208 , The smaller droplets also minimize the likelihood of damage to the LNC 208 by fluid action on the catalyst.

The SCR 210 is downstream of LNC 208 arranged to further reduce NO _x and remove ammonia from the exhaust stream. As in 15 is shown, the LNC can 208 and the SCR 210 adjacent to each other in a common housing 214 be arranged.

The reducing agent injector 202 Alternatively, it may also be configured as a nozzle for supplying unheated and pressurized reductant. The injector 202 may deliver an alcohol-based combustion engine fuel. Depending on the volatility of these fuels, an aerosol generator or atomizer may not be required to rapidly disperse the reductant in the exhaust gas.

16 shows a portion of one by the reference numeral 300 designated further exhaust aftertreatment system. The system 300 is the system 200 essentially similar. Therefore, similar elements retain their previously introduced reference numerals. In the in 16 As shown, the diesel particulate filter has been downstream offset and combined with the SCR device. Therefore, a reference numeral designates 302 a DPF with an SCR coating. Moving the DPF farther downstream makes the LNC 208 closer to the combustion engine 12 and at the miniature regeneration unit 26 arranged. Therefore, the temperature should be in the LNC 208 entering exhaust gas be greater than in a similar configuration in which the LNC 208 further away from the sources of energy.

The exhaust aftertreatment system 10 uses the relative positions of the miniature regeneration unit 26 , the diesel oxidation catalyst 30 and the aerosol generator 202 advantageous to the conversion efficiency of the LNC 208 to maximize. The through the LNC 208 The achieved NO _x reduction efficiency increases with increasing exhaust gas temperature. In addition, it should be noted that the DPF coated with an SCR material 302 in sufficient proximity to the miniature regeneration unit 26 and the diesel oxidation catalyst 30 is arranged to the SCR / DPF 302 to selectively regenerate as required. By using the aerosol generator 202 for supplying the reducing agent takes place before the entry of the exhaust gas into the LNC 208 an improved distribution and mixing of the reducing agent with the exhaust gas instead. There is an efficient NO _x reduction. The aerosol generator 202 improves the operating characteristics of the LNC 208 by injecting heated reducing agent. An undesirable reduction of the exhaust gas temperature is avoided.

17 shows a portion of another exhaust aftertreatment system 400 , In the aftertreatment system 400 is the LNC 208 further upstream and thus closer to the internal combustion engine 12 and to the miniature regeneration unit 26 added. This configuration increases NO _x conversion efficiency over a wider range of engine operating conditions, including cold starts. The miniature regeneration unit 26 heats the exhaust gas while the aerosol generator 202 the upstream of the LNC 208 injected reducing agent adds energy. The regeneration unit 26 may be located upstream from the lean _NOx catalyst 208 be arranged so that carbon deposits can be burned periodically or continuously from active sites of the catalyst. The regeneration of the lean _NOx catalyst 208 increases the NO _x conversion efficiency of the aftertreatment system 400 , It comes into consideration that the LNC 208 has a silver-based catalyst for use with alcohol-based reducing agents such as ethanol, E85, E93, E95 and the like. Acetaldehyde is produced in NO _x reduction at temperatures of 300 ° C or more as an active compound. By using the aerosol generator 202 Also known as an evaporator, the alcohol-based reductants may be broken down prior to contact with the silver-based catalyst to cause NO _x conversion to occur at temperatures less than 300 ° C. The use of the aerosol generator 202 also increases overall conversion efficiency at higher catalyst temperatures.

Optionally, an optional SCR device (not shown) may be located immediately downstream of the LNC 208 be arranged to perform an additional NO _x conversion and an ammonia reduction. The system 400 has a downstream of the LNC 208 and upstream of the DOC 30 and from the DPF 32 arranged hydrocarbon injector 28 on. The DOC 30 and the DPF 32 are in a common housing 402 arranged shown. To the DPF 32 to regenerate, causes the control unit 38 selective injection of a reductant, such as diesel fuel, through the hydrocarbon injector 28 downstream from the LNC 208 and upstream of the DOC 30 injected into the exhaust stream.

18 shows another exhaust aftertreatment system 500 , The aftertreatment system 500 is the aftertreatment system 300 essentially similar. Therefore, similar elements retain their previously introduced reference numerals. In particular, the system is different 500 from the system 300 in that the system 500 having a diesel particulate filter with a Lean-NO _x -Katalysatorbeschichtung instead of a coated with an SCR-DPF material. Installation space and cost can be reduced by implementing solutions such as those found in the aftertreatment system 300 and in the aftertreatment system 500 are shown.

During operation of the LNC / DPF 502 An exothermic chemical reaction takes place. The release of energy contributes to the regeneration of soot that is absorbed by the diesel particulate filter. In addition, regeneration of the DPF may occur concurrently with desulfation of the hydrocarbon LNC. The SCR facility 210 is downstream of the LNC / DPF 502 arranged to remove ammonia and further reduce NO _x .

19 shows another exhaust aftertreatment system 600 , The exhaust aftertreatment system 600 is the aftertreatment system 500 essentially similar. These systems are essentially the same, except that the aerosol generator 202 by a second reducing agent injector 602 is replaced. The second reductant injector 602 communicates with an additional reservoir 604 , A second reducing agent, such as an alcohol-based fuel, is in the container 604 stored and is the second reducing agent injector 602 selectively supplied. Alcohol-based fuels such as E85, E93 and E95 provide improved NO _x reduction efficiency as compared to using diesel fuel as a reducing agent. Instead of an aerosol generator, due to the low vapor pressure of the second reductant, an injector may be used to inject the alcohol-based fuel. Optionally, a refill container 604 with an easily available alcohol-based fuel rather than storing and distributing an ammonia source such as urea.

20 shows another exhaust aftertreatment system 700 with a LNC 208 and a SCR / DPF 302 in a common housing 702 are housed. The aerosol generator 202 communicates with the exhaust duct 14 upstream of the burner 704 , The burner 704 is configured so that all the exhaust gas that is the exhaust duct 14 flows through, even the burner 704 flows through and an inlet 706 of the housing 702 is supplied. The system 700 works that way through the aerosol generator 202 provided atomized reducing agent through the burner 704 Although warmed, but not by the burner 704 generated flame is burned. Therefore, the inlet 706 supplied with the reducing agent and heated exhaust gas to an improved operating range and a better cold start behavior of the LNC 208 to achieve. The burner 704 is with a coat 708 configured to perform this function. The burner generates a combustion flame in the jacket 708 , The reductant-off-gas mixture flows along an outer surface of the shell 708 to allow heat transfer to the exhaust gas without burning the reducing agent.

21 shows a by reference numerals 800 designated further exhaust aftertreatment system. The system 800 is the system 700 essentially similar, except that the aerosol generator 202 by a secondary reductant injector 802 is replaced. The secondary reductant injector 802 a secondary reductant is added, such as one in a supplemental reductant tank 804 stored alcohol-based fuel. The injected secondary reductant mixes with the exhaust passage 14 flowing through the exhaust gas and is passed through the burner 704 heated. The heated reducing agent and exhaust gas becomes the LNC 208 and the SCR / DPF 302 supplied to reduce unwanted NO _x emissions.

The above description of the embodiments is illustrative and illustrative. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are not generally limited to this particular embodiment, but are interchangeable where possible, and may be used in a selected embodiment, although not specifically illustrated or described. In addition, further exhaust aftertreatment systems are possible within the scope of the invention. For example, the foregoing configurations described as being equipped with an aerosol generator may also be configured to include a more common reductant injector for introducing a reductant into the exhaust gas at its ambient temperature. The embodiments may also be modified in various ways. Therefore, all such modifications are to be considered included within the scope of the present invention.

Claims (25)

A system for treating an exhaust stream from an internal combustion engine, the system comprising: a main exhaust passage, which is adapted to receive the exhaust gas flow from the internal combustion engine; a side branch communicating with the main exhaust duct; a side-branched regeneration unit for burning a fuel and heating the exhaust gas flowing through the main exhaust passage; a downstream of the regeneration unit in the main exhaust passage lean NO _x catalyst; means disposed downstream of the regeneration unit and upstream of the lean _NOx catalyst reducing agent injection means for injecting reducing agent particles in the exhaust gas stream; and a control unit for controlling the regeneration unit to increase the exhaust gas temperature and control the reducing agent injector to reduce NO _x in the lean NO _x catalyst. The system of claim 1, further comprising an oxidation catalyst and a particulate filter disposed downstream of the regeneration unit and upstream of the reductant injector in the main exhaust passage. System according to claim 2, further comprising a downstream from the lean _NOx catalyst selective catalytic reduction device. System _x catalyst and the selective catalytic reduction device are arranged in a spaced apart from the first housing the second housing according to claim 3, wherein the oxidation catalyst and the particulate filter are arranged in a first housing and the lean NO. The system of claim 1, wherein the Lean NO _x Catalyst comprising a support coated with a catalyst material particulate filter. The system of claim 5, wherein the reducing agent injection means is located downstream of the oxidation catalyst, and further comprising downstream from the lean _NOx catalyst selective catalytic reduction device. The system of claim 1, wherein the reductant injector includes an aerosol generator for heating and injecting a reductant. The system of claim 7, wherein the aerosol generator supplies reductant particles of less than one micron in diameter. System is arranged according to claim 1, further comprising an oxidation catalyst and a particulate filter downstream from the lean-NO _x catalyst within the main exhaust passage. The system of claim 1, further comprising a hydrocarbon injector downstream of the regeneration unit and upstream of an oxidation catalyst for injecting a hydrocarbon into the exhaust stream. The system of claim 1, further comprising a particle filter with a coating of a selective catalytic reduction material, wherein the coated fillets is disposed downstream from the lean _NOx catalyst. The system of claim 1, wherein the reductant injector injects an internal combustion engine fuel. The system of claim 12, wherein the regeneration unit is arranged directly upstream of the lean _NOx catalyst to provide exhaust gas having a temperature which is sufficiently high to burn off carbon deposits of active sites within the lean _NOx catalyst. A system for treating an exhaust stream from an internal combustion engine, the system comprising: an exhaust passage adapted to receive the exhaust stream from the internal combustion engine; a burner for burning a fuel and heating the exhaust gas flowing through the exhaust passage; a downstream from the burner in the exhaust passage lean NO _x catalyst; a upstream from the burner and upstream of the lean _NOx catalyst reducing agent injection means for injecting reducing agent particles in the exhaust gas stream; and a control unit for controlling the burner to raise the exhaust gas temperature and control the injector to reduce NO _x in the lean NO _x catalyst. The system of claim 14, further comprising a particle filter with a coating of a selective catalytic reduction material, the coated filter is located downstream from the lean _NOx catalyst. The system of claim 14, wherein the reductant injector includes an aerosol generator for heating and injecting a hydrocarbon reductant. The system of claim 16, wherein the aerosol generator comprises reducing agent particles having a Size of less than a micrometer in diameter. The system of claim 14, wherein the reducing agent comprises an alcohol-based fuel. The system of claim 14, wherein the burner has a jacket around which flows an exhaust gas reductant mixture, the burner producing a flame disposed within the shell. A system for treating an exhaust stream from an internal combustion engine, the system comprising: an exhaust passage adapted to receive the exhaust stream from the internal combustion engine; a burner for burning a fuel and heating the exhaust gas flowing through the exhaust passage; a disposed within the exhaust passage lean-NO _x catalyst to which the exhaust gas warmed by the burner receives directly before it flows through a different catalyst; a downstream from the burner and upstream of the lean _NOx catalyst hydrocarbon injection means for injecting a hydrocarbon into the exhaust stream; and a control unit for controlling the burner for increasing the exhaust gas temperature is arranged to a predetermined value for burning of active sites of the lean _NOx catalyst, carbon deposits. The system of claim 20, wherein the hydrocarbon comprises an alcohol-based fuel. The system of claim 20, wherein the hydrocarbon comprises a diesel fuel. The system of claim 20, further comprising an oxidation catalyst and a particulate filter disposed downstream of the regeneration unit in the main exhaust passage. The system of claim 20, wherein the reductant injector includes an aerosol generator for heating and injecting the hydrocarbon. The system of claim 24, wherein the aerosol generator supplies reductant particles of less than one micron in diameter.

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