DE102008045479A1 - Exhaust gas recirculation system for internal combustion engine in vehicle, has condensate water separator for separating and guiding separated condenser water via disposal pipeline into low pressure part of exhaust gas system - Google Patents

Abstract

The system has a condensate water separator (34) for separating condensate water from exhaust gas of a high pressure part (26) of an exhaust gas system. The condensate water separator guides the separated condenser water via a disposal pipeline (36) into a low pressure part (28) of the exhaust gas system. A cleaning unit comprises a filter for filtering water-insoluble or complex water-soluble substances from the condensate water. The cleaning unit comprises aluminum material for reaction with acid contained in the exhaust gas.

Description

The The invention relates to a system for recycling exhaust gas of an internal combustion engine according to claim 1, a heat exchanger according to claim 16 and a method for recirculation of exhaust gas an internal combustion engine according to claim 17th

at low-temperature EGR cooling (EGR = exhaust gas recirculation) directly with air or indirectly with low-temperature coolant is formed in the exhaust gas cooler condensate in larger Amount. This contains sulfuric and nitric acid and is therefore angry. That with the low-temperature exhaust gas cooling accumulating condensate is usually directly in the prior art supplied to the engine. Such a direct feed Condensate in the engine can cause corrosion of the material in the intake area lead the engine and in the cylinder itself.

The revelation US 2001 045 090 A1 concerns a similar problem. In the approach used in the US 2001 045 090 A1 is proposed, the condensate is separated in a low-pressure exhaust gas recirculation and fed back to the exhaust system. However, it should be noted that at the in the US 2001 045 090 A1 disclosed embodiment, no natural driving pressure gradient prevails, so that the condensate would actually have to be pumped into the exhaust pipe. But a pump is not described, causing problems in the execution of the US 2001 045 090 A1 revealed teaching may result.

It is therefore the object of the invention, a system for recycling exhaust gas of an internal combustion engine, a heat exchanger and a method for recirculating exhaust gas an internal combustion engine, which has improved properties to have.

These Task is through a system for repatriation exhaust gas of an internal combustion engine according to claim 1, a heat exchanger according to claim 16 and a method for recirculation of exhaust gas an internal combustion engine according to claim 17 solved. Favorable embodiments The invention are further characterized by the subclaims Are defined.

The The present invention provides a system for recycling exhaust gas of an internal combustion engine, wherein the internal combustion engine an exhaust system having a high pressure and a low pressure part, the system having a separator unit formed is to enter from an exhaust gas of the high pressure part of the exhaust system To separate condensate and the condensate via a disposal line into the low-pressure part of the exhaust system.

Further the present invention provides a heat exchanger for Receiving an exhaust gas from a high pressure part of an exhaust system an internal combustion engine, wherein the heat exchanger is formed to the received from the internal combustion engine To cool exhaust gas, to extract a condensate and the condensate at least partially a low pressure part of the exhaust system supply

• – Entnehmen von Abgas aus dem Hochdruckteil des Abgassystems;
• – Abscheiden eines Kondensats aus dem entnommenen Abgas; und
• – Einleiten zumindest eines Teils des Kondensats in den Niederdruckteil des Abgassystems.

The present invention also provides a method for recirculating exhaust gas of an internal combustion engine, wherein the internal combustion engine has an exhaust system with a high-pressure and a low-pressure part, the method comprising the following steps:

• Removing exhaust gas from the high pressure part of the exhaust system;
• - Separation of a condensate from the exhaust gas removed; and
• - Introducing at least a portion of the condensate in the low pressure part of the exhaust system.

The The present invention is based on the finding that a better Corrosion protection of the engine or parts thereof is then given when the harmful substances condense out of the exhaust gas and the condensate at least partially over the low pressure part the exhaust system is disposed of. Thus, no big comes Amount of harmful components of the exhaust more in the engine block or the cylinder back and leads there to material wear. Also, can the Low-temperature exhaust gas cooling with the inventive concept advantageous operate in areas where a lot of condensate is generated and it also thereby to corrosion phenomena without use the approach of the invention would come. At the same time, the arrangement of the exhaust gas treatment on the High pressure side of the exhaust system a favorable pressure difference in the discharge of the condensate in the low-pressure part exploited the exhaust system, whereby a pump for disposal of the Condensate can be omitted.

In another embodiment of the invention, wherein the Exhaust system an exhaust gas treatment unit in the low pressure part of Exhaust system, the disposal line may be formed, around at least part of the condensate at one point in the low pressure part the exhaust system to be introduced in the exhaust flow to the exhaust gas treatment unit located. This can be expensive or sensitive components the exhaust gas treatment unit (for example, from abrasion by non-water-soluble or aggressive components of the condensate) become.

Cheap It is also when the internal combustion engine is a supply air system having a low pressure and a high pressure part that then the separation unit is connected to a mixing unit to a exhaust gas purified by the separation unit or part of the condensate supply the supply air having the high pressure. In this case, the corrosion of parts of the internal combustion engine be prevented, with the favorable properties of Exhaust gas recirculation in the supply air of the internal combustion engine anyway can be used.

The system may also include a cleaning unit as a corrosion protection unit against corrosion of the internal combustion engine by constituents of the exhaust gas, wherein the cleaning unit comprises the separation unit and wherein the cleaning unit is adapted to at least one acid, which originates from at least a part of the exhaust gas of the high-pressure part of the exhaust system, by a reaction with a sacrificial material to obtain a purified exhaust gas and at least partially supply the purified exhaust gas to a supply air having a high pressure. Such an embodiment of the invention offers the advantage that the aggressive substances are neutralized before re-introduction of the exhaust gas into the engine. By cooled in the separator exhaust gases (below the condensation point of the harmful substances) can also be a very deep cooling of the supply air supplied and a low intake pipe temperatures realize, resulting in low NO _x - and good fuel consumption even in engines with one for the low temperature -Abgasrückführkühlung not optimized material concept can be realized. The arrangement of the cleaning unit on the high-pressure side also has favorable effects on the supply (a part) of the condensate or the purified exhaust gas in the high-pressure side supply air, since in this case also no high pressure loss between the feed air and the exhaust gas or condensate is feared or an additional pressure increase of the condensate by means of a pump may not be necessary.

In a favorable embodiment of the invention For example, the cleaning unit may comprise a sacrificial material which is in the Operation of the corrosion protection device is consumed. hereby is ensured in a technically simple and cost-effective manner, that the harmful substances in the exhaust gas before a supply of the Exhaust gas or a condensate on the exhaust gas in the internal combustion engine be neutralized. The sacrificial material can be provided in quantity be that an exchange in the enterprise to take place only very rarely Has.

Also For example, the cleaning unit may be configured to move through the reaction the acid with the sacrificial material a water-insoluble or difficult to form water-soluble corrosion product. This allows a technically very simple and inexpensive to implement the approach to the separation of harmful Substances in the exhaust gas from the (aqueous) condensate.

Especially It is favorable if the cleaning unit aluminum than Sacrificial material for the reaction with that contained in the exhaust Acid includes, as a result of the deposition of harmful Substances in the exhaust gas through a cost-effective available Material becomes possible.

Very The non-water-soluble ones can also simply be used extract water-soluble substances from the condensate, if a filter is used which can be designed to be such filter out non-water-soluble substances from the condensate. This filter provides a condensate with a very high degree of purity which subsequently fed back to the exhaust gas or the supply air can be without corrosion in the internal combustion engine too cause. Furthermore, the filter on a technically easy to implement physical principle such as sedimentation of the sparingly soluble Substances are based in the aqueous concentrate.

In In another embodiment of the invention, the cleaning unit further comprise a downstream in the condensate flow the filter pump, wherein the pump may be configured to supply the filtered condensate cleaned exhaust gas of the high-pressure part of the exhaust system or the supply air, which has a high pressure supply. This offers the advantage that by using the pump as possible low pressure losses in the supply air when feeding the Condensate in the high-pressure part of the supply air system occur wherein such pressure losses of the charge air or supply air adversely on the combustion characteristics of a fuel combustion in the fuel machine.

Also, in another embodiment of the invention, the cleaning unit may include a venturi to supply the purified condensate to the exhaust gas of the high-pressure part of the exhaust system or the high-pressure supply air. This offers the advantage that due to the speed increase of the feed air flow, a further cooling of this air occurs, which has a positive effect on the combustion properties in the cylinders of the internal combustion engine. At the same time, however, the injector principle can be used in the supply of condensate, so that the condensate already by this physical effect in case of failure of a possibly used pump can be safely added to the purified exhaust gas or the feed air.

Around to be able to continue to use a heat contained in the exhaust gas, The separating unit or the cleaning unit can also be designed as a heat exchanger be to at least a portion of the exhaust gas of the internal combustion engine cool. The exchanged heat can then for Further purposes such as a heating of a passenger compartment of a used by the internal combustion engine driven vehicle become. Also, in this case, a combination of cooling the exhaust gas (or at least part of it) and a purge of the exhaust gas (for example, by providing the sacrificial material in the cleaning unit designed as a cooling element) be achieved in a combined element, which reduces costs affects the overall system to be manufactured.

If in the high pressure part of the exhaust system, at least one cooling unit contained, it may also be advantageous that the separation unit or downstream of the cleaning unit in the exhaust flow of the cooling unit is or at least partially disposed in the cooling unit is. In this case, (for example, by the cleaning) a additional cooling of the exhaust gas can be achieved which is to be supplied to the supply air, so that thereby a further improvement of the combustion characteristics in the cylinders the internal combustion engine can be achieved.

In another embodiment of the invention, wherein the Cooling unit in the high-pressure part of the exhaust system, a high-temperature and a low-temperature cooling unit, the Separator unit or cleaning unit in the low-temperature refrigeration unit be arranged or the low-temperature cooling unit in Be arranged exhaust downstream flow. This ensures that Conveniently, the cleaning of the exhaust gas with the lowest available exhaust gas temperature takes place, so on the one hand the acid is not too reactive and the sacrificial material too quickly consumed and on the other hand, the supply air of the internal combustion engine with a cold condensate or one possible cold purified exhaust gas can be fed, resulting in a optimal combustion behavior in the cylinders of the internal combustion engine results.

Also can in another embodiment of the invention, the Separator unit or the cleaning unit one of the cooling unit comprise downstream separate neutralization unit in the exhaust gas flow, which is designed to remove the acid from the exhaust gas of the high-pressure part the exhaust system by a reaction with a sacrificial material tie. As a result, the separate neutralization unit optionally be replaced, for example, when consumes the sacrificial material is. Replacement of a separate neutralization unit a more complex separator / neutralizer / filter unit In particular financial advantages, as only one smaller and less complex (and therefore usually cheaper) Unit is to exchange.

In According to a further embodiment of the invention, the separation unit or the cleaning unit is designed to at least the condensate partially only in at least one combustion cylinder of the internal combustion engine, in particular in each combustion cylinder of the internal combustion engine supply the supply air having the high pressure. This offers the advantage that the combustion properties in the individual cylinders by a separate supply of supply air and cleaned condensate can be adjusted individually.

The The invention will be described below with reference to the accompanying drawings exemplified in more detail. It shows:

1 a schematic representation of components of an internal combustion engine wherein an embodiment of the present invention is used together with the internal combustion engine;

2 a schematic representation of another embodiment of the present invention and its arrangement to a component of the internal combustion engine;

3 a schematic representation of a third embodiment of the present invention and its arrangement to a component of the internal combustion engine;

4 a schematic representation of a fourth embodiment of the present invention and its arrangement to a component of the internal combustion engine; and

5 a flowchart of an embodiment of the present invention as a method.

The same or similar elements are provided in the following figures of the drawings with the same or similar reference numerals, wherein a repeated description of these elements is omitted. Furthermore, the figures of the drawings, the description and the claims contain numerous features in combination. It is clear to a person skilled in the art that these features also can be considered individually or they can be combined to other, not explicitly described combinations here.

According to the Embodiments of the present invention, as they Be described in more detail below, the resulting Condensate is deposited directly after the exhaust gas cooler and kept away from the engine. This can be done at the high-pressure EGR the natural pressure gradient between exhaust gas cooler and exhaust system can be used. Furthermore, in the condensate neutralize existing acids; either directly in the cooler or subsequently. The remaining water could be in a filter of (corrosion) particles is and will be cleaned subsequently returned to the exhaust gas. Stay like that get the positive properties of the condensate (i.e. Cleaning the EGR cooler or lowering the intake manifold and / or Cylinder temperature).

1 shows a schematic representation of components of an internal combustion engine and an embodiment of the present invention. The internal combustion engine 10 includes a supply air inlet 12 , via the feed air to a turbocharger 14 is supplied. The turbocharger 14 compresses the sucked feed air and thus provides a separator between a low pressure part 13 and a high pressure part 15 a supply air system of the internal combustion engine 10 dar. The compressed charge or supply air is in the high pressure part 15 following a high pressure cooler unit 16 (HP-CAC = high pressure charge air cooler = high-pressure intercooler) supplied, which cools the compressed charge air (= supply air) in order to obtain the best possible combustion characteristics by a cold charge air when burning fuel in an engine block 18 to reach. The through the high pressure cooler unit 16 cooled feed air is then (at least partially) with a purified condensate (especially water from the condensate) of the exhaust gas of the engine block 18 (or with the purified gas itself) through a mixing unit 20 mixed and the cooled and mixed with condensate or exhaust feed air into the engine block 18 passed in whose cylinders 22 the combustion of fuel is carried out with the (enriched) supply air. Due to the cooled supply or charge air and the further cooling by the supplied water or the condensate can thus reduce the combustion temperature in the cylinders 22 of the engine block 18 achieved, for example, in a low NOx concentration in the exhaust gas from the cylinders 22 of the engine block 18 results.

After the combustion of the fuel in the cylinders 22 of the engine block 18 becomes at least a part of the exhaust gas produced by the combustion of a drive turbine of the turbocharger 14 supplied and relaxed around the turbocharger 14 drive. After flowing through the turbocharger 14 becomes the exhaust gas of an exhaust aftertreatment unit 24 (For example, a catalyst or a soot filter) and then released into the environment. The turbocharger 14 thus acts as a separator between a high pressure part 26 and a low pressure part 28 an exhaust system of the internal combustion engine 10 ,

Another part of the exhaust gas from the cylinders 22 of the engine block 18 is via an adjustable exhaust gas recirculation valve or bypass valve 29 High pressure side taken from the exhaust system and a high-temperature exhaust gas recirculation cooling unit 30 (HT-EGRC = high temperature exhaust gas recirculation cooler = high-temperature exhaust gas circulation chiller unit) which is adapted to the very hot exhaust gases from the cylinders 22 of the engine block 18 to cool. The cooled exhaust gas subsequently becomes a low-temperature exhaust gas recirculation cooling unit 32 (LT-EGRC = low-temperature exhaust gas recirculation cooler = low-temperature exhaust gas circulation chiller unit) fed, which further cooling the exhaust gas from the cylinders 22 of the engine block 18 ensures to ensure the lowest possible temperature of the feed air after the admixture of the exhaust gas or a condensate from the exhaust gas into the feed air. The separation between high-temperature cooler unit 30 and low temperature radiator unit 32 has a better cooling effect, as a single cooling unit, as by separate components heat conduction in the radiator unit can be prevented and thus a colder subsequent (low-temperature) radiator unit for further cooling of the exhaust gases can be provided. Also, the high-temperature exhaust gas recirculation cooling unit 30 and / or the low-temperature exhaust gas recirculation cooling unit 32 be implemented as a heat exchanger in order to use the heat of the exhaust gas for other purposes such as a heating function can.

In the in 1 illustrated embodiment is further in the exhaust gas flow after the low-temperature exhaust gas recirculation cooling unit 32 a separator 34 arranged, which is adapted to separate a condensate from the exhaust gas. The condensate, which contains the harmful and corrosive components such as acid particles, can through the disposal line 36 directly after the exhaust aftertreatment unit 24 in the low pressure part 28 introduced the exhaust system and thereby be disposed of (for example via an exhaust). By introducing the condensate, which in the high pressure part 26 of the exhaust system is deposited in the low-pressure part 28 the exhaust system can be further by the pressure drop of the use of a pump to promote the condensate in the leaching Avoid contact point.

This in 1 illustrated embodiment can thus be summarized as follows: The condensate is after the low-temperature exhaust gas cooler 32 via a condensate separator 34 taken. From there it will be over a line 36 passed into the hot exhaust line and there with the exhaust stream of the engine 18 mixed. The supply line is expediently after the turbine 14 ie at the lowest possible pressure level. To corrosion in the expensive components of exhaust aftertreatment 24 to avoid, may be an introduction to the exhaust aftertreatment system 24 meaningful. The pressure difference between the EGR line in the high pressure part 26 the exhaust system (up to 7 bar) and the low-pressure part 28 the exhaust system in which the exhaust system 24 is arranged (about 1 bar), usually enough to dispose of the separated condensate quantities without a pump is needed.

In the other 2 to 4 Embodiments of the invention are shown, which additionally or alternatively to the in 1 pictured separation unit 34 can be used in an analogous place. The in the 2 to 4 Shown Abscheideeinheiten correspond respectively to in 1 illustrated separation unit 34 , The in the 2 to 4 shown arrangement of components can also be designed in each case as a compact heat exchanger in a unit whose components are possibly directly interchangeable.

In 2 is a schematic representation of another embodiment of the present invention and its arrangement reproduced to a component of the internal combustion engine. According to the in 2 illustrated embodiment is the Niedertemperaturabgaskühler 32 Made of aluminum, so it due to the low-temperature exhaust gas cooler 32 precipitating condensate to a corrosive attack on the aluminum of the low-temperature exhaust gas cooler 32 comes. As a result, the acids contained in the exhaust gas are neutralized. The resulting condensate now consists essentially of water, but also contains corrosion products (eg aluminum sulfate). The condensate can thus be supplied to the engine without causing corrosion there. If necessary, the corrosion products can be removed from the condensate by the condensate after Niedertemperaturabgaskühlers 32 in a condensate separator 34 is separated, then through a filter 38 passed (and thus cleaned) and then the recirculated exhaust gas or the supply air (which has a high pressure) again via a mixing unit 20 or a Venturi nozzle 42 is added. The transport through the filter can be either with a pump 40 and / or by means of a at the mixing point of the condensate to the gas flow (from feed air and / or exhaust) arranged Venturi system 42 (or one in 2 not shown mixing unit 20 ) respectively.

Furthermore, the low temperature exhaust gas cooler 32 be made of stainless steel, so that the neutralization of the condensate can take place only after the cooler. There are two possibilities here, with a first possibility in the exemplary embodiment 3 is shown as a schematic representation. In this case, a "victim" component becomes a neutralizer 44 used and directly after the low-temperature exhaust gas cooler 32 installed. Then proceed with the condensate as already described above. The sacrificial component or the neutralizer 44 can either in the exhaust gas cooler outlet or after low temperature exhaust gas cooler 32 to be ordered.

Further, in the second possible embodiment, using a stainless steel cooler 32 (as in 4 is shown) the condensate in a separator 34 deposited and in a separate component 44 be neutralized; then it is again added to the flow of the recirculated exhaust gas (or the supply air). Again, it may be useful, as described above, to filter the condensate after neutralization in order to remove any harmful corrosion products. It is advantageous if the substance used for neutralization produces water-insoluble or sparingly soluble corrosion products, since these can be deposited better in a filter.

In an alternative or further embodiment The invention may be an admixture of the reintroduced condensate in the charge air or in the intake manifold (after mixture of charge air and exhaust gas) instead of recirculated exhaust gas or cylinder-selective, d. H. take place a mixing point per cylinder, so that a good uniform distribution of the mixed feed air-exhaust mixture results.

By The approach described above can be the treatment the condensate also for a low-temperature exhaust gas cooling operate in areas where a lot of condensate is generated and it may possibly lead to corrosion. By the thus possible very deep cooling arise low intake pipe temperatures. As a result, can be low NOx and good fuel consumption also on engines with a for realize the non-optimized NT-EGR cooling material concept.

In 5 Fig. 3 is a flow chart of an embodiment of the present invention as a method. The flowchart be meets a procedure 50 to protect an internal combustion engine 10 against corrosion, the internal combustion engine 10 a supply air system with a low pressure 13 and a high pressure part 15 and an exhaust system with a high-pressure 26 and a low pressure part 28 having. The procedure 50 includes a step of removal 52 of exhaust from the high pressure part 26 the exhaust system and a step of depositing 54 a condensate from the exhaust gas removed. Furthermore, the method comprises 50 a step of initiating 56 at least part of the condensate in the low-pressure part 28 the exhaust system. In a parallel or additional processing path, the method 50 a step of binding 58 of at least one acid from the exhaust gas of the high pressure part 26 of the exhaust system by reacting with a sacrificial material to obtain a purified exhaust gas. This is followed by the procedure 50 a step of at least partially feeding 60 of the purified exhaust gas to a supply air having a high pressure.

10

Internal combustion engine

12

Supply air intake

13

Low-pressure part of the intake air system

14

turbocharger

15

High-pressure part of the intake air system

16

High-pressure charge air cooler

18

block

20

mixing unit

22

cylinder

24

exhaust gas treatment unit

26

High-pressure part the exhaust system

28

Low-pressure part the exhaust system

29

Exhaust gas recirculation valve, Bypass valve

30

High-temperature exhaust gas recirculation cooling unit heat exchangers

32

Low-temperature exhaust gas recirculation cooling unit heat exchangers

34

(Condensate) separator, separation unit

36

disposal line

38

filter

40

pump

42

venturi system

44

neutralizer

50

method for the return of exhaust gas of an internal combustion engine

52

step the removal of exhaust gas from the high pressure part of the exhaust system

54

step the removal of a condensate from the exhaust gas removed

56

step introducing at least part of the condensate into the low-pressure part the exhaust system

58

step the binding of at least one acid from the exhaust gas the high-pressure part of the exhaust system is due to a reaction with a sacrificial material to obtain a purified exhaust gas

60

step at least partially supplying the purified exhaust gas to a supply air of the supply air system, which has a high pressure

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - US 2001045090 A1 [0003, 0003, 0003, 0003]

Claims (18)

System ( 34 . 36 . 38 . 40 . 42 . 44 ) for the return of exhaust gas of an internal combustion engine ( 10 ), wherein the internal combustion engine ( 10 ) an exhaust system with a high pressure ( 26 ) and a low pressure part ( 28 ), the system ( 34 . 36 . 38 . 40 . 42 . 44 ) a separation unit ( 34 ), which is adapted to from an exhaust gas of the high-pressure part ( 26 ) of the exhaust system to separate a condensate and the condensate via a disposal line ( 36 ) in the low pressure part ( 28 ) of the exhaust system. The system of claim 1, wherein the exhaust system comprises an exhaust treatment unit (10). 24 ) in the low-pressure part ( 28 ) of the exhaust system, characterized in that the disposal line ( 36 ) is formed to at least a portion of the condensate at a location in the low-pressure part ( 28 ) of the exhaust system which is located in the exhaust gas flow after the exhaust gas treatment unit ( 24 ) is located. System according to one of claims 1 or 2, wherein the internal combustion engine ( 10 ) a supply air system with a low pressure ( 13 ) and a high pressure part ( 15 ), characterized in that the separation unit ( 34 ) with a mixing unit ( 20 ) to pass through the separation unit ( 34 ) to supply purified exhaust gas or a part of the condensate to the supply air having the high pressure. System according to claim 3, characterized in that the system comprises a cleaning unit ( 34 . 38 . 40 . 42 . 44 ) as a corrosion protection unit against corrosion of the internal combustion engine ( 10 ) by constituents of the exhaust gas, wherein the purification unit ( 34 . 38 . 40 . 42 . 44 ) the separation unit ( 34 ) and wherein the cleaning unit ( 34 . 38 . 40 . 42 . 44 ) is formed to at least one acid from at least a portion of the exhaust gas of the high-pressure part ( 26 ) of the exhaust system is to bind by a reaction with a sacrificial material to obtain a purified exhaust gas and at least partially supply the purified exhaust gas to a supply air having a high pressure. System according to claim 4, characterized in that the cleaning unit ( 32 . 38 . 40 . 42 . 44 ) comprises a sacrificial material, which in operation of the system corrosion protection device ( 34 . 36 . 38 . 40 . 42 . 44 ) is consumed. System according to claim 4 or 5, characterized in that the cleaning unit ( 34 . 38 . 40 . 42 . 44 ) is formed to form a water-insoluble or poorly water-soluble corrosion product by the reaction of the acid with the sacrificial material. System according to one of claims 4 to 6, characterized in that the cleaning unit ( 34 . 38 . 40 . 42 . 44 ) Aluminum as a sacrificial material for the reaction with the acid contained in the exhaust gas. System according to claim 7, characterized in that the cleaning unit ( 34 . 38 . 40 . 42 . 44 ) a filter ( 38 ), which is designed to filter out water-insoluble or poorly water-soluble substances from the condensate. System according to claim 8, characterized in that the cleaning unit ( 38 . 40 . 42 . 44 ) also in the condensate flow to the filter ( 38 ) downstream pump ( 40 ), wherein the pump ( 40 ) is formed to the filtered condensate the purified exhaust gas of the high pressure part ( 26 ) of the exhaust system or the supply air having a high pressure. System according to one of claims 4 to 9, characterized in that the cleaning unit ( 34 . 38 . 40 . 42 . 44 ) a Venturi nozzle ( 42 ) to the purified condensate the exhaust gas of the high-pressure part ( 26 ) of the exhaust system or the supply air having a high pressure. System according to one of claims 1 to 10, characterized in that the separation unit ( 34 ) or the cleaning unit ( 34 . 38 . 40 . 42 . 44 ) is designed as a heat exchanger to at least a part of the exhaust gas of the internal combustion engine ( 10 ) to cool. System according to one of claims 1 to 11, wherein in the high-pressure part ( 26 ) of the exhaust system at least one cooling unit ( 30 . 32 ), characterized in that the separation unit ( 34 ) or the cleaning unit ( 34 . 38 . 40 . 42 . 44 ) in the exhaust flow of the cooling unit ( 30 . 32 ) or at least partially in the cooling unit ( 32 ) is arranged. A system according to claim 12, wherein the cooling unit ( 30 . 32 ) in the high pressure part ( 26 ) of the exhaust system, a high-temperature ( 30 ) and a low-temperature cooling unit ( 32 ), characterized in that the separation unit ( 34 ) or the cleaning unit ( 34 . 38 . 40 . 42 . 44 ) in the low-temperature refrigeration unit ( 32 ) or the low-temperature cooling unit ( 32 ) is arranged downstream in the exhaust gas flow. System according to claim 12 or 13, characterized in that the separation unit ( 34 ) or the cleaning unit ( 34 . 38 . 40 . 42 . 44 ) one of the cooling unit ( 32 ) downstream in the exhaust flow separate neutralization unit ( 44 ) configured to remove the acid from at least part of the exhaust gas of the high-pressure part ( 26 ) of the exhaust system by reacting with a sacrificial material. System according to one of claims 4 to 14, characterized in that the separation unit ( 34 ) or the cleaning unit ( 34 . 38 . 40 . 42 . 44 ) is formed in order to at least partially remove the condensate only in at least one combustion cylinder ( 22 ) of the internal combustion engine ( 10 ), in particular in each combustion cylinder ( 22 ) of the internal combustion engine ( 10 ) supply the supply air having the high pressure. Heat exchanger ( 30 . 32 . 34 . 36 ) for receiving an exhaust gas from a high-pressure part ( 26 ) of an exhaust system of an internal combustion engine ( 10 ), wherein the heat exchanger ( 30 . 32 . 34 ) is configured to cool the exhaust gas taken from the internal combustion engine, to extract a condensate therefrom, and to at least partially remove the condensate from a low-pressure part ( 26 ) supply the exhaust system. Procedure ( 50 ) for the return of exhaust gas of an internal combustion engine ( 10 ), wherein the internal combustion engine ( 10 ) an exhaust system with a high pressure ( 26 ) and a low pressure part ( 28 ), the method ( 50 ) comprises the following steps: 52 ) of exhaust gas from the high-pressure part ( 26 ) of the exhaust system; - deposition ( 54 ) a condensate from the exhaust gas withdrawn; and - initiate ( 56 ) At least a portion of the condensate in the low pressure part of the exhaust system. A method according to claim 17, wherein the internal combustion engine ( 10 ) a supply air system with a low pressure ( 13 ) and a high pressure part ( 15 ) and wherein the method further comprises the further steps of: - binding ( 58 ) of at least one acid from the extracted exhaust gas of the high-pressure part ( 26 ) of the exhaust system by a reaction with a sacrificial material to obtain a purified exhaust gas; and - at least partially feeding ( 60 ) of the purified exhaust gas to a supply air having a high pressure.