DE102006057151A1 - Urea-containing liquid transferring device for nitrogen oxide reduction of exhaust gas of internal combustion engine of motor vehicle, has container accommodating liquid, where container has rib unit that is arranged in sections in channel - Google Patents

Abstract

The The invention relates to a device for transferring a urea-containing liquid in gaseous ammonia-containing mixture for nitrogen oxide reduction of exhaust gas Internal combustion engine for a motor vehicle with at least a first flow channel (2) for exhaust gas a motor vehicle, at least one container (3, 31, 61) for receiving a urea-containing liquid (4), the container (3, 31, 61) at least one rib element (5, 65) for heat transfer between exhaust gas and the urea-containing liquid (4), wherein the at least one rib element (5, 65) at least in sections in the first flow channel (2) is arranged.

Description

The The present invention relates to apparatus, a system and a Method for transferring a urea-containing liquid in gaseous ammonia-containing mixture for nitrogen oxide reduction of exhaust gas Combustion engine.

by virtue of the more stringent exhaust emission regulations regarding the Nitrogen oxides (NO, NO2) for Internal combustion engines of motor vehicles become the exhaust gas of internal combustion engines treated.

Known Selective catalytic reduction (SCR) systems are selective catalytic reduction.

The chemical reaction of the reduction is selective, i. it will not be reduces all exhaust components, but essentially only the Nitrogen oxides NO, NO2.

To the Sequence of the reaction ammonia NH3 is needed, which admixed to the exhaust gas becomes. The products of the reaction are water and nitrogen.

In In automotive engineering, the SCR method is used, in particular to reduce pollutant emissions in diesel trains. The the Ammonia is not used in pure form in the SCR process, but in the form of an aqueous Urea solution, especially a 32.5 percent Urea solution.

Known is the injection of urea solution into the exhaust system by means of Dosing pump or injector. Formed from the aqueous urea solution by the hydrolysis reaction in the exhaust gas ammonia, water and carbon dioxide. The nitrogen oxides in the exhaust gas react with the resulting ammonia.

The Amount of urea solution to be injected is from the motor Nitrogen oxide emission dependent, in particular the engine speed, and the engine torque.

The urea solution is stored in a separate tank in the vehicle.

The Adding the liquid Urea solution can only at an exhaust gas temperature of more than 200 ° C done. As for the addition Urea solution at a lower exhaust gas temperature intermediates arise, the are difficult to degrade and, for example, the openings of a catalyst can clog. About that It can also cause unpleasant odors come through unreacted ammonia. Furthermore, a certain Length of the Exhaust line needed, so that the reaction is complete can.

Further is known, the watery Urea solution, also referred to as AdBlue, not liquid to introduce into the exhaust system, but in a reactor under the action of particular thermal energy to convert into the gas phase and the gaseous Reaction product zuzufürhren the exhaust stream.

Out of he WO 99/67512 For example, an exhaust gas purification system for de-stemming exhaust gases from combustion units is known.

Furthermore, from the WO 2006/087551 A1 a thermo-hydrolysis reactor for producing an ammonia-containing gas is known.

It Object of the present invention, a device of the input To improve the type mentioned and space-saving form. Especially Thermoelectric voltages should be avoided in the device.

The The object is solved by the features of claim 1.

It is a device for transferring a urea-containing liquid in gaseous ammonia-containing mixture for nitrogen oxide reduction of exhaust gas Internal combustion engine for a motor vehicle proposed.

The Device has at least a first flow channel, in particular a Exhaust pipe, for Exhaust gas of a motor vehicle.

Further the device has at least one container for holding a urea-containing liquid, especially from AdBlue, on. The container has at least one ribbed element, in particular a plurality of rib elements, for heat transfer between the exhaust gas and the urea-containing liquid.

The at least one rib element, in particular the rib elements, are at least partially arranged in the first flow channel.

A advantageous development of the invention is characterized in in that the at least one rib element, in particular the rib elements, flow channel-like are formed. In this way, in the at least one rib element particularly advantageously stores a urea-containing liquid and / or heated or overheated. Furthermore, it may be particularly advantageous a gaseous ammonia-containing mixture be stored or flow in it.

Further has the at least one rib element, in particular, the Rib elements, at least one rib wall. The at least one rib element, In particular, the rib elements are at least in sections as a collection room for the gaseous formed ammonia-containing mixture. This way can be special advantageously a gaseous ammonia-containing mixture are collected.

A advantageous development of the invention is characterized in in that the device comprises a number of rib elements which are arranged substantially parallel to each other. In this way can be a urea-containing liquid be particularly advantageous heated or overheated.

A advantageous development of the invention is characterized in in that at least one second flow channel in each of the rib elements, especially for removal of gaseous ammonia-containing Mixture of the collecting space and / or for feeding into the at least one first flow channel for exhaust is arranged. In this way, gaseous ammonia-containing mixture particularly advantageous fed to the exhaust stream and space particularly advantageous be saved.

A advantageous development of the invention is characterized in that the second flow channel is designed as a tubular element having a tube wall.

A advantageous development of the invention is characterized in in that between the rib wall and the tube wall is a liquid droplet retention element is arranged to prevent passage of liquid droplets of urea-containing liquid in the collection room. The liquid droplet retention element can be formed particularly advantageous wire mesh made of metal be.

A advantageous development of the invention is characterized in in that in the at least one liquid retention element, especially in the liquid retention elements, at least one sensor for temperature measurement, in particular a thermocouple, is arranged to detect a level height exceeding a liquid level the urea-containing liquid in the at least one rib element, in particular in the rib elements. In this way can be particularly advantageous cost Thermocouple for measuring the excess used a liquid level become. The arrangement in the liquid droplet retention element can be particularly advantageous a measuring gain effect be achieved.

A advantageous development of the invention is characterized in in that the at least one second flow channel can be moved without tension with respect to the at least one rib member and / or formed with respect to the at least one container is. That way you can Thermoelectric voltages are particularly advantageous avoided.

A advantageous development of the invention is characterized in that second flow channels into one Lead to collecting channel, wherein the collecting channel in the first flow channel for exhaust gas empties.

A advantageous development of the invention is characterized in that the collecting channel as a condensation-preventing collecting channel is formed, such that the gaseous ammonia-containing mixture to the confluence in the at least one first flow channel for exhaust gas in the gaseous Phase exists.

Under "Condensation-preventing Collecting channel "is in particular a collecting duct to understand the heat and / or another thermal energy is applied or from a medium surrounded that has a temperature that is at least the same or greater than the condensation temperature of the gaseous ammonia-containing mixture is so that the ammonia-containing mixture until the feed in the exhaust duct, in particular the first flow channel, not condensed.

A advantageous development of the invention is characterized in that the at least one rib element at least in sections a curved one Course has to prevent passage of the urea-containing liquid in the collection room. In this way, thermoelectric voltages in the Rib elements particularly advantageous verhin changed. Furthermore, a be particularly advantageous prevents liquid droplets of urea-containing liquid get into the collection room.

A advantageous development of the invention is characterized in in that rib elements have a rib element section surface, wherein the rib element section surface at least in sections in the container protrudes. In this way, by heat transfer from the exhaust gas into the urea-containing liquid, the urea-containing liquid heated particularly advantageous or evaporated.

An advantageous development of the invention is characterized in that the projecting into the container rib element section surface over a container height of the container changes, in particular increases or decreases over the container height. In this way, the urea-containing liquid can be particularly advantageously heated or evaporated, in particular, even at a low level of the liquid level in the container.

The invention is further a system comprising a device according to any one of claims 1 to 13, with an internal combustion engine for a motor vehicle and with at least a first heat exchanger for charge air cooling of charge air for provided the internal combustion engine.

• – Erwärmung einer harnstoffhaltigen Flüssigkeit bis zum Sieden, so dass sich ein gasförmiges ammoniakhaltiges Gemisch bildet
• – Sammeln des gasförmigen ammoniakhaltigen Gemischs in einem Sammelraum
• – regelbare Einleitung des gasförmigen ammoniakhaltigen Gemischs in einen ersten Strömungskanal für Abgas eines Verbrennungsmotors eines Kraftfahrzeugs

In addition, an inventive method for nitrogen oxide reduction of exhaust gas of an internal combustion engine is provided for a motor vehicle. The process according to the invention comprises the following process steps:

• - Heating a urea-containing liquid to boiling, so that forms a gaseous ammonia-containing mixture
• - collecting the gaseous mixture containing ammonia in a collecting space
• - Controllable introduction of the gaseous ammonia-containing mixture in a first flow channel for exhaust gas of an internal combustion engine of a motor vehicle

Further advantageous embodiments of the invention will become apparent from the dependent claims and from the drawing. The backrest of the dependent claims relate on the device according to the invention, on the system according to the invention as well as to the inventive method.

embodiments The invention are illustrated in the drawing and are explained in more detail below, wherein a restriction the invention should not take place thereby. Show it

1 a device for heating or evaporating a urea-containing liquid, so that a gaseous ammonia-containing mixture is formed for nitrogen oxide reduction of exhaust gas of an internal combustion engine;

2 a detail A of a rib of the device according to the invention;

3a / 3b : the operation of the sensor for detecting a level overshoot (PHÜ);

4 : a further illustration of the device according to the invention;

5 a second embodiment of the device according to the invention;

6a a third embodiment of the device according to the invention;

6b an isometric view of the third embodiment;

7a : an isometric view of the rib block of the third embodiment;

7b a bottom view of the rib block of the third embodiment;

1 shows a device 1 for heating or evaporating a urea-containing liquid 4 so that a gaseous ammonia-containing mixture is formed for nitrogen oxide reduction of exhaust gas of an internal combustion engine.

The device 1 has a container 3 for receiving a urea-containing liquid, which is hereinafter referred to as urea solution. The urea solution is the container via an opening, not shown 3 fed. The container three has a rectangular cross section with rounded corners. In another embodiment, not shown, the container 3 a round, oval or square cross-sectional area. The container is made of a metal such as steel, in particular stainless steel, or made of ceramic or of a fiber composite material.

Out of the container 3 are three ribs 5 educated. In another embodiment, one to three or more than three ribs are out of the container 3 educated. Ribs 5 are arranged substantially parallel to each other. They have a round, angular or elliptical cross section or a cross section of the combination of the aforementioned forms. Ribs 5 are hollow inside. Ribs 5 have a rib wall 6 on. Ribs 5 are made of a thermally conductive and / or corrosion resistant material, such as steel or stainless steel or other metal.

In each case a rib 5 is at least a second flow channel 8th arranged below as a gas pipe 8th referred to as. The gas pipe 8th is essentially concentric in the rib 5 but in another embodiment may be eccentric in the rib 5 be arranged.

The gas pipe 8th open in the container 3 into a collection channel 13 , The collection channel 13 leads the gaseous ammonia-containing mixture in the exhaust stream of the engine.

2 shows a detail A of a rib of the device according to the invention. Identical features are provided with the same reference numerals as in FIG 1 ,

The urea solution 4 has in the rib 5 a liquid level height FB. The liquid droplet retention element 10 is a wire mesh as a metal wire. The liquid droplet retention element 10 is thermally conductive and in particular thermally conductive with the rib wall 6 Connected. The gas pipe 8th has a pipe wall 9 on. In particular, liquid droplet retention element 10 between the pipe wall 9 and the rib wall 10 arranged. The liquid droplet retention element 10 Prevents liquid droplets of urea solution in the plenum gaseous ammonia-containing mixture.

Due to the arrangement of the device 1 in a first flow channel, not shown in this figure 2 for exhaust gas of an internal combustion engine, hereinafter referred to as exhaust duct 2 is called, the urea solution 4 in the container 3 and / or in the ribs 5 heated and / or vaporized or overheated. The result is a gaseous ammonia-containing mixture that has CO2 and water vapor. The mixture passes through the liquid droplet retention element 10 and enters the collection room 7 , Due to the high pressure, it continues to flow into the gas pipe via an unspecified opening 8th , in particular the gas pipes, and further through the collecting duct 13 in the exhaust pipe 2 ,

3a and 3b show the operation of the sensor 12 for detecting a level overshoot (PHÜ). Identical features are provided with the same reference numerals as in the previous figures.

In 3a and 3b the temperature profiles in the areas of the cross section are a rib element 5 shown. The temperature of the exhaust gas of the internal combustion engine in the exhaust pipe, not shown 2 is denoted by TA. The temperature of the liquid urea solution 4 in the region of the liquid level FP is denoted by TF. The temperature that the sensor 12 mist is denoted by TS. For the temperature TS: TF ≤ TS ≤ TW ≤ TA The sensor 12 is in the liquid droplet retention element 10 arranged. The metal wire of the liquid droplet retention element 10 points mainly due to the heat conduction between the rib wall 6 and the metal wire, the temperature TW of the rib wall 6 on. Rises the urea solution 4 to the liquid droplet retention element 10 the metal wire is cooled and essentially assumes the temperature TF. In this way, a kind of reinforcing effect for measuring the temperature is achieved. The exceeding of a level height PHU can be unambiguous with the sensor 12 , In particular, a thermocouple can be found. In this way you can use a cheap sensor. With this sensor 12 For example, a pump for pumping the urea solution or another heater, not shown, can be controlled.

4 shows a further illustration of the device according to the invention 1 , wherein the same features are provided with the same reference numerals as in the previous figures. 4 shows a valve device 40 for inflow control of urea solution 4 in the container 3 ,

5 shows a second embodiment of the device according to the invention 30 , Identical features are provided with the same reference numerals as in the previous figures.

The device 30 has a container 31 basically, like the container 3 is trained. Ribs 5 are bent at least in sections. In particular, the rib elements 5 than like sections of a circle. In another embodiment, not shown, the rib elements 5 partially or completely wavy and / or zigzag-shaped. This will prevent liquid droplets from entering the sump 7 reach. Furthermore, a liquid droplet retention element may also be used 10 , which may be designed as a sieve-like in the plenum 7 be arranged.

In the 6a and 6b . 7a and 7b is a third embodiment of the device according to the invention 60 shown. Identical features are provided with the same reference numerals as provided in the previous figures.

The device 60 has a container 61 which is essentially like the container 3 is trained. The rib elements 65 of the rib block 66 at least partially protrude into the exhaust duct 2 , About the feeders 68 gaseous ammonia-containing mixture is in the exhaust passage 2 guided. The in the case 3 arranged rib elements 65 are plate-shaped. They are arranged in a star shape with respect to a rib block axis RBA. The rib elements 65 have rib section area 63 which is wetted by urea solution. About the container height 62 changes the rib density, so that even at a low liquid level height of the urea solution 4 sufficient gaseous ammonia-containing mixture is produced.

The rib areas of the ribbed element 65 in the exhaust duct 2 are substantially arranged parallel to each other, but can also be arranged at an angle of 0 ° to 90 ° to each other.

The Features of the various embodiments can be combined with each other. The invention is also for others can be used as the areas shown.

Claims (15)

Device for transferring a urea-containing liquid into gaseous ammonia-containing mixture for nitrogen oxide reduction of exhaust gas of an internal combustion engine for a motor vehicle, having at least one first flow channel ( 2 ) for exhaust gas of a motor vehicle, • at least one container ( 3 . 31 . 61 ) for receiving a urea-containing liquid ( 4 ), the container ( 3 . 31 . 61 ) at least one rib element ( 5 . 65 ) for heat transfer between the exhaust gas and the urea-containing liquid ( 4 ) characterized in that • the at least one rib element ( 5 . 65 ) at least in sections in the first flow channel ( 2 ) is arranged. Device according to claim 1, characterized in that the at least one rib element ( 5 ) is formed flow channel-like and / or a rib wall ( 6 ) and / or at least in sections as a collecting space ( 7 ) is formed for the gaseous ammonia-containing mixture. Device according to one of the preceding claims, characterized in that the device ( 1 . 30 . 60 ) a number of rib elements ( 5 . 65 ), which are arranged substantially parallel to each other. Device according to claim 3, characterized in that in the rib elements ( 5 ) in each case at least one second flow channel ( 8th ) for discharging the gaseous ammonia-containing mixture from the collecting space ( 8th ) and / or for feeding into the at least one first flow channel ( 2 ) is arranged for exhaust gas. Apparatus according to claim 4, characterized in that the second flow channel ( 8th ) as a tubular element ( 8th ) is formed, which a pipe wall ( 9 ) having. Device according to claim 5, characterized in that between the rib wall ( 6 ) and the pipe wall ( 9 ) a liquid droplet retention element ( 10 ) is arranged to prevent passage of liquid droplets ( 11 ) of the urea-containing liquid ( 4 ) into the collection room ( 7 ). Device according to one of the preceding claims, characterized in that in the at least one liquid droplet retention element ( 10 ) at least one sensor ( 12 ) for measuring the temperature, in particular a thermocouple, is arranged for detecting a level exceeding (PHÜ) of a liquid level (FP) of the urea-containing liquid ( 4 ) in the at least one rib element ( 5 ). Apparatus according to claim 4 to 7, characterized in that the at least one second flow channel ( 8th ) free of tension relative to the at least one rib element ( 5 ) and / or with respect to the at least one container ( 3 . 31 . 61 ) is trained. Device according to one of claims 4 to 8, characterized in that second flow channels ( 8th ) in a collecting channel ( 13 ), the collecting duct ( 13 ) in the first flow channel ( 2 ) for exhaust gas flows. Apparatus according to claim 9, characterized in that the collecting channel ( 13 ) as a condensation-preventing collecting channel ( 13 ) is formed, such that the gaseous ammonia-containing mixture to the confluence in the at least one first flow channel ( 2 ) is present for exhaust gas in the gaseous phase. Device according to one of the preceding claims, characterized in that the at least one rib element ( 5 ) at least in sections has a curved course to prevent passage of liquid droplets ( 11 ) of the urea-containing liquid ( 4 ) into the collection room ( 7 ). Device according to one of the preceding claims, characterized in that rib elements ( 65 ) a rib element portion surface ( 63 ), wherein the rib element portion surface ( 63 ) at least in sections into the container ( 61 protrudes. Apparatus according to claim 12, characterized in that in the container ( 61 ) protruding rib element portion surface ( 63 ) over a container height ( 62 ) of the container ( 61 ), in particular about the container height ( 62 ) increases or decreases. System comprising a device (according to one of previous claims, an internal combustion engine for a motor vehicle and at least a first heat exchanger for intercooling of Charge air for the internal combustion engine. Method for reducing the nitrogen oxide of exhaust gas of an internal combustion engine for a motor vehicle comprising the following process steps: heating a urea-containing liquid ( 4 ) until boiling, forming a gaseous mixture containing ammonia. • Collecting the gaseous ammonia-containing mixture in a collecting space ( 7 ) • controllable introduction of the gaseous ammonia-containing mixture into a first flow channel ( 2 ) for exhaust gas of an internal combustion engine of a motor vehicle