DE102016218274A1 - Apparatus for recovering water, in particular for a water injection device of an internal combustion engine - Google Patents

Abstract

The present invention relates to a device for recovering water from exhaust gas, in particular for a water injection device of an internal combustion engine. The device (1) comprises a first space (2), in which an exhaust gas flow (50) can be flowed in, and which is connected to the environment in which a first pressure (p1) prevails. The first space (2) is at least partially filled with an extraction medium and arranged such that the exhaust stream (50) in the first space (2) in contact with an extraction medium (51) for selectively receiving water and / or water vapor from the exhaust gas stream (50). 50) can be brought by the extraction medium (51). The device (1) further comprises a second space (3) which is under a second pressure (p2) which is smaller than the first pressure (p1) and connected to the first space (2), so that in the extraction medium (51) absorbed water vapor and / or absorbed water in the second space (3) from the extraction medium (51) is releasable. The second space (3) is further connected to a condenser (9), wherein the condenser (9) is arranged to condense the water vapor (52) released in the second space (3). Furthermore, the invention relates to a method for recovering water from exhaust gas.

Description

State of the art

The present invention relates to a device for recovering water and a water injection device of an internal combustion engine having a device according to the invention and a method for obtaining water, in particular for a water injection device of an internal combustion engine.

In order to reduce a tendency to knock and to reduce high exhaust gas temperatures proposals are made recently to carry out a water injection in internal combustion engines. The water can either be injected directly into a combustion chamber of the internal combustion engine or into an intake tract of the internal combustion engine. In order to install such water injection systems in series in vehicles, it must be ensured that sufficient water in a water tank or the like. Is present. In this case, it would be desirable if a user of the vehicle is not forced to automatically fill water into the water tank of the vehicle, for example via a refill pipe. From the DE 102012207903 A1 a device for obtaining water from an exhaust system of an internal combustion engine is known. In this case, a condenser is provided in order to condense water vapor contained in the exhaust gas of the internal combustion engine. Since the water is obtained directly from the exhaust gas, corrosive components are contained in the recovered water to a large extent, which attack in particular metal parts of the exhaust system and / or a water injection system. Therefore, it is actually essential that a purification of the directly obtained from the exhaust gas water condensate is performed. Only in this way can damage to sensitive components of the water injection system, in particular water injectors, be avoided.

Disclosure of the invention

The device according to the invention for recovering water from exhaust gas, in particular for a water injection device of an internal combustion engine, with the features of claim 1 has the advantage that water can be recovered from exhaust gas, wherein the recovered water condensate has no corrosive constituents. The water-bearing components of the water injection device and the internal combustion engine itself are significantly less burdened with particular attention to a corrosion load. Thereby, it is possible that the water can be used directly in a water injection device of an internal combustion engine, without expensive purification of the condensed water would be necessary. In this case, the device according to the invention is very simple and robust and can be used easily over several years in a vehicle with a water injection device. There are no maintenance or the like. For maintenance of the device according to the invention for water extraction necessary. This is inventively achieved by a selective absorption of water or water vapor from the exhaust gas by means of an extraction medium. In this case, the device for obtaining water comprises a first space and a second space. In the first space an exhaust gas stream can be flowed in, wherein the first space is connected to the environment in which a first pressure prevails. The first space is at least partially filled with an extraction medium and further arranged such that the exhaust gas flow in the first space in contact with the extraction medium for selectively receiving from the exhaust gas flow through the extraction medium of water and / or water vapor can be brought. Furthermore, the second room is connected to the first room. The second space is at a second pressure which is less than the first pressure, so that water vapor and / or absorbed water in the second area of the second space can be released from the extraction medium in the extraction medium. Furthermore, a condenser is provided which is connected to the second space and is arranged to condense the water vapor released in the second space. The extraction medium is preferably liquid. In the apparatus, the water extracted from the exhaust gas stream and / or the extracted water vapor are dissolved in the first space in the extraction medium. Due to the second pressure, which is less than the first pressure, the solubility of water in the extraction medium in the second space decreases and water vapor is released from the extraction medium. Thus, in the invention no direct condensation of water vapor from the exhaust gas, but a two-stage process, wherein water vapor is separated from the exhaust stream first by the extraction medium and taken up in the extraction medium, then released by means of the lower pressure in the second space from the extraction medium, and then condensed in a condenser. In the context of the invention, the extraction medium is also referred to as entraining medium. The extraction medium advantageously has a better affinity for water than for other undesirable components of the exhaust gas, such as corrosive constituents. That is, the solubility of water in the extraction medium is better than the solubility of these undesired components in the extraction medium. The recovery of water by the described device can also be achieved by operation above the dew point of water.

The dependent claims show preferred developments of the invention.

Preferably, a first conveying element is connected to the second space, which generates the second pressure (negative pressure relative to ambient pressure) in the second space. Thus, it is possible to maintain the second pressure in the second space, so that the water vapor can be released from the loaded extraction medium in the second space under all conditions. This is particularly advantageous in a water injection device to ensure that sufficient water is available for water injection. In this case, pressure sensors may preferably be arranged in the first space and in the second space, which are set up to detect the first pressure and the second pressure. By a controller can then be selected according to the operating point of the conveyor element preferably. In particular, the conveying element is designed as a pump.

Preferably, the apparatus further comprises a supply channel connected to the first space for supplying extraction medium into the first space. Thus, the first space can be filled with new extraction medium, which can lead to increased efficiency in the absorption of water vapor and / or water by the extraction medium.

According to a particularly preferred embodiment of the present invention, a first connecting channel and a second connecting channel are provided, which are each arranged in the first space and / or in the second space. In the first connecting channel and / or in the second connecting channel, a second conveying element for feeding extraction medium from the first region of the second space into the first space and returning the extraction medium from the first space to the first area of the second space is arranged. Thereby, the extraction medium is circulated between the first space and the second area of the second space. Particularly preferably, the conveying element is arranged in the first connecting channel, whereby extraction medium can be conveyed from the first region of the second space into the first space.

Preferably, an end region of the supply channel and / or an end region of the first connection channel is formed as a riser tube, in particular with angled sub-tubes. The sub-tubes are advantageously angled such that the extraction medium is supplied via the end region of the feed channel and / or the end region of the first connection channel into the first space in a first flow direction that is substantially equal to a second flow direction of the exhaust gas flow in the first space , This means that a main component of the first flow direction is parallel in the same direction to a main component of the second flow direction. Particularly preferably, the partial tubes are angled downwards. This configuration of the end region of the feed channel and / or of the end region of the first connection channel enhances the process of selective removal of water and / or water vapor from the exhaust gas flow through the extraction medium.

Advantageously, an end region of the supply channel and / or an end region of the first connection channel is arranged centrally in the first space. As a result, a uniform contact between the exhaust gas stream and the extraction medium is achieved, so that a better extraction of water and / or water vapor from the exhaust gas stream is possible.

An end region of the feed channel and / or an end region of the first connection channel are preferably designed such that the extraction medium enters the first space in a first flow direction which is substantially equal to a second flow direction of the exhaust gas flow in the first space. Under the formulation that the first flow direction of the extraction medium in the first space is substantially equal to the second flow direction of the exhaust gas flow in the first space, it is understood that a main component of the second flow direction of the exhaust gas flow and a main component of the first flow direction of the extraction medium in the first space parallel to each other in the same direction, ie not opposed. The consequence of this is that the contact between the exhaust stream and the extraction medium can be enhanced, since in this case the contact time and the contact area between the exhaust gas and the extraction medium are greater compared to the case of opposite flow directions.

Preferably, the feed channel and / or the first connection channel open into a first region of the first space in which there is no extraction medium. The first space preferably has a second area in which the extraction medium, in particular the extraction medium laden with water and / or water vapor, can collect. The first area and the second area of the first space communicate with each other. Further preferably, the second space has a third area that communicates with the second area of the first space and in which extraction medium can collect. The third region communicates with a fourth region of the second space in which no extraction medium is located.

The first space and the second space are preferably each formed as a tank.

Further preferably, a shut-off element is arranged on an exhaust gas inlet of the first space. By means of the shut-off element, the exhaust gas flow, which flows into the first space, can be regulated. The shut-off can be controlled by a controller.

Furthermore, the present invention relates to a water injection device comprising a device described above for recovering water.

Another aspect of the invention relates to an internal combustion engine having such a water injection device.

The advantages explained with reference to the described device for obtaining water are also given in the water injection device and the internal combustion engine.

It is also a method for recovering water from exhaust gas, in particular for a water injection device of an internal combustion engine, proposed. According to the method, an exhaust gas stream is fed into a first space, which is connected to the environment in which a first pressure prevails. The exhaust stream comes into contact with an extraction medium in the first space for selectively receiving water and / or water vapor from the exhaust stream through the extraction medium. The extraction medium laden with water and / or steam is fed into a second space which is at a second pressure which is less than the first pressure. Thus, water vapor taken up in the extraction medium and / or absorbed water in the second space is liberated from the extraction medium. The released water vapor is then condensed. Thus, the water vapor fraction can be separated off from the exhaust gas, which can be detected as a substance mixture, before the condensation process. This leads to pure water without corrosive components that could damage, for example, the water-bearing components of a water injection device. The corrosive constituents comprise, in particular, inorganic acid which arises from the combustion of sulfur-containing components and results from the formation of nitrogen oxides during combustion and subsequent reaction with the water vapor which is always present in the exhaust gas.

Preferably, the extraction medium enters the first space in a first flow direction that is substantially equal to a second flow direction of an exhaust gas flow in the first space. This means that a main component of the exhaust gas flow in the first space in the same direction is parallel to a main component of the flow of the extraction medium in the first space.

Particularly preferably, the extraction medium is supplied into the first space at an angle to the second flow direction of the exhaust gas stream. By this is meant that the exhaust gas stream contacts the extraction medium at an angle to each other. For this purpose, one end of a supply channel and / or one end of the first connection channel in the first space are inclined relative to the second flow direction of the exhaust gas flow in the first space. The end of the supply channel or the end of the connection channel preferably corresponds to one end of an end region of the supply channel or one end of an end region of the first connection channel in the first space.

The extraction medium preferably circulates between the first space and the second space. Thus, the extraction medium can be used several times. As a result, on the one hand, a compact design is possible, since it dispenses with an additional tank for storing the extraction medium. On the other hand, the effort and costs for refilling new extraction medium are reduced or eliminated.

Particularly preferably, the extraction medium comprises a polyhydric alcohol, in particular glycerol. A polyhydric alcohol means that the molecule has more than one R-OH group. Alternatively or additionally, ionic liquids and / or specific oils may be used as the extraction medium.

Short description of the drawing

Hereinafter, a preferred embodiment of the invention will be described in detail with reference to the accompanying drawings. In the drawing is:

1 a schematic, simplified view of a preferred embodiment of the present invention.

Preferred embodiment of the invention

The following is with reference to the 1 a device 1 for recovering water from exhaust gas described in detail. In particular, the device 1 in conjunction with a water injection device 18 an internal combustion engine 19 used.

Like from the 1 can be seen, the device comprises 1 a first room 2 and one second room 3 , The rooms 2 and 3 are each designed in particular as a tank.

In the first room 2 is an exhaust gas flow 50 via an exhaust inlet 4 einströmbar. Further, an exhaust outlet 5 provided by the exhaust gas from the first room 2 can be dissipated. The release or the shut-off of the exhaust gas inlet 4 via a shut-off element 6 , The shut-off element 6 is preferably by a control unit 8th controlled, allowing the opening and closing of the shut-off element 6 to the particular requirements of the water injection device 18 is adjusted.

The first room 2 is connected to the environment in which a first pressure p1 prevails. Thus prevails in the first room 2 the first pressure p1. Further, the first room 2 set up so that the exhaust gas flow 50 in the first room 2 in contact with a liquid extraction medium 51 for selectively receiving water and / or water vapor from the exhaust stream 50 through the extraction medium 51 can be brought.

Furthermore, the first room 2 with the second room 3 connected. In the second room 3 There is a second pressure p2, which is smaller than the first pressure p1 of the first room, so that in the first room 2 absorbed by the extraction medium water vapor and / or the absorbed water in the second space 3 can be released again from the extraction medium.

At the second room 3 is preferably a capacitor 9 connected. The capacitor 9 is also set up in the second room 3 to condense released water vapor. For this purpose, a cooler is preferred 90 used.

The second pressure p2 is through a first conveying element 10 allows that at the second room 3 connected. Thus, the released water vapor from the second room 3 to the condenser 9 be guided faster. The first conveying element 10 , which is formed in this embodiment as a pump or compressor, is advantageously by the control unit 8th operated. This makes it possible to have the second pressure p2 in the second space 3 maintain.

Between the first room 2 and the second room 3 are a first connection channel 11 and a second connection channel 12 intended. The two connection channels 11 . 12 form together with a second conveying element 14 a circuit between the first room 2 and the second room 3 , The second conveyor element 14 , which is preferably designed as a pump, is at the first connection channel 11 arranged. By this arrangement, extraction medium 51 from the second room 3 in the first room 2 arrive, and to the second room 3 to be led back.

In this case, the first connection channel is used 11 as a supply channel and the second connection channel 12 as a return channel for the extraction medium. Furthermore serve the first room 2 and the second room 3 as a kind of communicating vessels.

Alternatively or additionally, for feeding extraction medium into the first room 2 preferably an additional supply channel 13 be provided (in 1 dashed lines drawn).

From the 1 is also evident that an end 110 of the first connection channel 11 in the middle of the first room 2 is arranged. The end area 110 is preferably designed as a riser. Further preferred is the end region 110 with downwardly angled sub-tubes 111 provided so that extraction medium in the first room 2 in a first flow direction F1, which is substantially equal to a second flow direction F2 of the exhaust gas flow 50 in the first room 2 is. "Substantially" means that a main component of the first flow direction F1 and a main component of the second flow direction F2 are parallel to each other in the same direction. For example, the exhaust gas and the extraction medium in this embodiment flow substantially from top to bottom. The partial tubes 111 belong to one end of the first connection channel 11 ,

The capacitor 9 preferably communicates with a water tank 15 , The water tank 15 is preferably directly or by means of a conduit with a third conveying element 16 connected. The third conveying element 16 is set up, water from the water tank 15 to a water injector 17 the water injection device 18 the internal combustion engine 19 to lead. The third conveying element 16 is preferably designed as a pump.

The second conveyor element 14 , the third conveying element 16 as well as the water injector 17 are advantageously by the control unit 8th controlled.

The function of the device according to the invention 1 for the recovery of water or the process for obtaining water is as follows. The 1 shows the device 1 in a normal mode.

First, the exhaust gas flow 50 the first room 2 fed. In the first room 2 becomes the exhaust gas of the exhaust gas flow 50 with extraction medium 51 brought into direct contact with the extraction medium 51 the first room 2 through the first connection channel 11 by means of the second conveying element 14 is supplied. The first connection channel 11 serves as a feed channel for the extraction medium 51 ,

So in the first room 2 Water vapor and / or water contained in the exhaust gas from the extraction medium 51 selectively absorbed. The corrosive components of the exhaust gas thus remain in the exhaust gas, which then from the first room 2 through the exhaust outlet 5 Will get removed.

In particular, the extraction medium 51 a first area 21 of the first room 2 fed, in which the loading of the extraction medium with water vapor and / or water from the exhaust stream 50 he follows. The first area 21 goes into a second area 22 of the first room 2 over, in which the extraction medium 51 can collect.

Preferably, the extraction medium flows 51 in the first room 2 in the first flow direction F1, which is substantially equal to the second flow direction F2 of the exhaust gas flow 50 in the first room 2 is. Further preferably, the extraction medium passes 51 in the first room 2 at an angle α to the second flow direction F2 of the exhaust gas flow 50 , Thereby, the selective absorption of water vapor and / or water from the exhaust gas due to a longer contact of the exhaust gas flow 50 with the extraction medium 51 supported.

The extraction medium loaded with water and / or steam 51 is then via the second connection channel 12 in a third area 31 of the second room 3 recycled.

By the second pressure p2 of the second room 3 , which is smaller than the first pressure p1, the solubility of the water in the extraction medium decreases 51 , Thus becomes water vapor 52 from the extraction medium 51 that is in the first area 31 of the second room 3 located in a fourth area 32 of the second room 3 Approved.

The second pressure p2 is through the first conveying element 10 generated, wherein the first conveying element 10 at the fourth area 32 is appropriate. The fourth area 32 thus corresponds to a suction for the first conveyor element 10 ,

The extraction medium 51 is through the second conveyor element 14 back to the first room 2 promoted. Thus, the extraction medium circulates 51 between the first room 2 and the second room 3 ,

The extraction medium used is preferably a polyhydric alcohol, in particular glycerol. Other substances, such as ionic liquids or special oils, are also possible as extraction media.

The released water vapor 52 is about the first conveying element 10 the capacitor 9 fed. In the condenser 9 becomes the water vapor 52 by means of the cooler to the water condensate 53 ,

From the condenser 9 gets the water condensate 53 in the water tank 15 , When a water injection is requested, the water injector becomes 17 the water injection device 18 using the third conveyor element 16 with water from the water tank 15 provided.

The process described above can be repeated several times to ensure a continuous and efficient recovery of water. In the device 1 and by the method of recovering water from exhaust gas, upstream separation of water from the exhaust gas is enabled, resulting in the recovery of very pure water. Furthermore, the amount of heat that has to be removed in order to obtain liquid water is also reduced because only a partial flow and not the entire exhaust gas flow is cooled below the dew point. Thus, even with limited cooling power still water from the exhaust gas can be condensed, resulting in a space-saving design of the device 1 leads.

It should be noted that other configurations are also possible, for example with regard to the control of the shut-off element, the conveying elements, etc.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 102012207903 A1 [0002]

Claims (13)

Device for recovering water from exhaust gas, in particular for a water injection device of an internal combustion engine, comprising: - a first space ( 2 ), in which an exhaust gas flow ( 50 ) and which is connected to the environment in which a first pressure (p1) prevails, - wherein the first space ( 2 ) at least partially with an extraction medium ( 51 ) and the first room ( 2 ) is set up such that the exhaust gas flow ( 50 ) in the first room ( 2 ) in contact with the extraction medium ( 51 ) for selectively receiving water and / or water vapor from the exhaust stream ( 50 ) through the extraction medium ( 51 ), - a second room ( 3 ), which is under a second pressure (p2), which is smaller than the first pressure (p1), and is connected to the first space, so that in the extraction medium ( 51 ) received water vapor and / or absorbed water in the second space ( 3 ) from the extraction medium ( 51 ) is releasable, and - a capacitor ( 9 ), with the second room ( 3 ) and is set up in the second room ( 3 ) released water vapor ( 52 ) to condense. Apparatus according to claim 1, characterized in that a first conveying element ( 10 ) at the second room ( 3 ) connected to the second pressure (p2) in the second space ( 3 ) generated. Device according to one of the preceding claims, characterized by a supply channel ( 15 ), with the first room ( 2 ) to extraction medium ( 51 ) in the first room ( 2 ). Device according to one of the preceding claims, characterized by: - a first connection channel ( 11 ) and a second connection channel ( 12 ) between the first room ( 2 ) and the second room ( 3 ), and - a second conveying element ( 14 ) in the first connection channel ( 11 ) and / or in the second connection channel ( 12 ) for circulating extraction medium ( 51 ) between the first room ( 2 ) and the second room ( 3 ). Apparatus according to claim 3 or 4, characterized in that an end region of the feed channel ( 15 ) or an end region of the first connection channel ( 11 ) is formed as a riser, in particular with angled sub-tubes. Device according to one of claims 3 to 5, characterized in that an end region of the feed channel and / or an end region ( 110 ) of the first connection channel ( 11 ) is designed such that the extraction medium ( 51 ) in the first room ( 2 ) passes in a first flow direction (F1), which is substantially equal to a second flow direction (F2) of the exhaust gas stream ( 50 ) in the first room ( 2 ). Water injection device comprising a device ( 1 ) for the recovery of water according to any one of the preceding claims. Internal combustion engine, comprising a water injection device ( 18 ) according to claim 7. Process for obtaining water from exhaust gas, in particular for a water injection device of an internal combustion engine, comprising the steps of: - supplying an exhaust gas flow ( 50 ) in a first room ( 2 ), which is connected to the environment in which a first pressure (p1) prevails, - contacting the exhaust gas flow ( 50 ) with an extraction medium ( 51 ) in the first room ( 2 ) for selectively receiving water and / or water vapor from the exhaust stream ( 50 ) through the extraction medium ( 51 ), - feeding the extraction medium loaded with water and / or water vapor ( 51 ) into a second room ( 3 ), which is below a second pressure (p2), which is smaller than the first pressure (p1), so that in the extraction medium ( 51 ) received water vapor and / or absorbed water in the second space ( 3 ) from the extraction medium ( 51 ), and - condensing the water vapor released ( 52 ). Process according to claim 9, characterized in that the extraction medium ( 51 ) in the first room ( 2 ) in a first flow direction (F1) which is substantially equal to a second flow direction (F2) of an exhaust gas flow ( 50 ) in the first room ( 2 ). Process according to claim 10, characterized in that the extraction medium ( 51 ) in the first room ( 2 ) at an angle (α) to the second flow direction (F2) of the exhaust gas flow ( 50 ) is supplied. Method according to one of claims 9 to 11, characterized in that the extraction medium ( 51 ) between the first room ( 2 ) and the second room ( 3 ) circulates. Method according to one of claims 9 to 12, characterized in that the extraction medium ( 51 ) comprises a polyhydric alcohol, in particular glycerol.

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