DE102016113380A1 - Method for operating an internal combustion engine and internal combustion engine - Google Patents

Abstract

Method for operating an internal combustion engine (1) with an exhaust gas charging system (2) and with an exhaust aftertreatment system (3), wherein the exhaust gas charging system (2) comprises an exhaust gas turbocharger (8) with a turbine (10) and a compressor (9), wherein the exhaust aftertreatment system (3) having a catalyst (12), upstream of and downstream of the catalyst (12) positioned shut-off devices (14, 15) and a bypass (13) with a further shut-off device (16) to the catalyst (12), and wherein for conducting an exhaust gas flow via the bypass (13) the upstream and downstream of the catalyst (12) positioned shut-off devices (14, 15) closed and the further shut-off device (16) of the bypass (13) is opened. Then, when the shut-off devices (14, 15) positioned upstream and downstream of the catalyst (12) are closed and the further shut-off device (16) of the bypass (13) is opened, an exhaust gas partial flow is applied to the catalyst (12).

Description

The invention relates to a method for operating an internal combustion engine with an exhaust gas charging system and an exhaust gas aftertreatment system. Furthermore, the invention relates to an internal combustion engine, a system of several internal combustion engines and a method for operating such a system.

In combustion processes in stationary internal combustion engines, which are used for example in power plants, as well as combustion processes in non-stationary internal combustion engines, which are used for example on ships, resulting in nitrogen oxides, these nitrogen oxides typically in the combustion of sulfur-containing fossil fuels, such as coal, hard coal , Brown coal, petroleum, heavy fuel oil or diesel fuels. Therefore, such internal combustion engines are assigned exhaust aftertreatment systems that serve the cleaning, in particular the denitrification, of the exhaust gas leaving the internal combustion engine.

To reduce nitrogen oxides in the exhaust gas, so-called SCR catalysts are used in practice in exhaust gas aftertreatment systems known from practice. In a SCR catalyst, a selective catalytic reduction of nitrogen oxides, wherein for the reduction of nitrogen oxides as a reducing agent ammonia (NH ₃ ) is required. The ammonia (NH ₃ ) or an ammonia precursor substance, such as urea, for this purpose, is introduced into the exhaust gas upstream of the SCR catalyst in liquid form, wherein the ammonia or the ammonia precursor substance upstream of the SCR catalyst with the exhaust gas is mixed. For this purpose, mixing paths between the introduction of the ammonia or of the ammonia precursor substance and the SCR catalyst are provided according to the practice.

Then, when such an internal combustion engine is used with an exhaust gas charging system and an exhaust aftertreatment system, for example, on a ship, the internal combustion engine is operated in areas with different emission legislations and emission limits to be observed differently. If, for example, an internal combustion engine of a ship is operated in regions with low nitrogen oxide emission requirements, such as on the high seas, the nitrogen oxide limit values to be observed can already be met by purely engine measures so that the exhaust gas does not have an SCR catalytic converter to comply with the emission limit values must be led. In this case, the exhaust aftertreatment system, in particular an SCR catalytic converter of the exhaust aftertreatment system, can then be deactivated.

In this case, in order to avoid aging of the catalysts when the catalysts are deactivated, in this case catalysts are shut off from the exhaust gas stream via shut-off devices positioned upstream and downstream of the catalyst, and then bypass the exhaust gas past the catalyst. However, since such shut-off devices do not always close completely, uncontrolled exhaust gas leakage into the catalytic converter can occur. In particular, when heavily sulfur-containing fuels, such as heavy oil or residual oil, are burned in the engine, the same can be damaged by an uncontrolled exhaust gas leakage into the catalyst, in particular by condensing sulfuric acid contained in the exhaust gas and causing corrosion in the catalyst. This is a disadvantage.

From the WO 2015/158948 A1 a system for protecting an SCR catalyst is known, the system comprising a heating system for the SCR catalyst, and wherein the heating system comprises a compressed air supply. Starting from the compressed air supply, the SCR catalytic converter can be supplied with compressed air. About the heating system, the modules of the catalyst can be heated.

Proceeding from this, the present invention has the object, a novel method for operating an internal combustion engine with an exhaust gas charging system and an exhaust aftertreatment system and a method for operating a system of several such internal combustion engines, such an internal combustion engine and to create a system of several such internal combustion engines.

This object is achieved by a method for operating an internal combustion engine according to claim 1. According to the invention, when the shut-off devices positioned upstream and downstream of the catalytic converter are closed and the further shut-off device of the bypass is opened, the exhaust gas partial flow is applied to the catalytic converter.

The invention uses exhaust gas to protect the catalyst. Exhaust gas with correspondingly high temperatures is available anyway. Therefore, no compressed air source and no heater are required. The invention makes it possible to protect catalysts from aging in a particularly advantageous manner with a low outlay in terms of apparatus, namely when they are deactivated and exhaust gas is routed past them via the bypass. The catalysts are then flushed with a partial exhaust stream.

According to an advantageous development, the partial exhaust gas stream conducted over the catalyst is regulated in such a way that the temperature in the catalyst is at least 120 ° C., preferably at least 130 ° C., particularly preferably at least 200 ° C. Hereby, the catalyst can be particularly effectively protected from aging.

The inventive method for operating a system of several internal combustion engines is defined in claim 5. The internal combustion engine according to the invention is in claim 7 and the inventive system of internal combustion engine is defined in claim 12.

Preferred embodiments of the invention will become apparent from the dependent claims and the description below. Embodiments of the invention will be described, without being limited thereto, with reference to the drawings. Showing:

1 a block diagram of a first internal combustion engine according to the invention to illustrate the inventive method for operating the same;

2 a block diagram of a second internal combustion engine according to the invention to illustrate the inventive method for operating the same; and

3 a block diagram of a system according to the invention of several internal combustion engine to illustrate the inventive method for operating the same.

1 schematically shows an internal combustion engine 1 with an exhaust charging system 2 and an exhaust aftertreatment system 3 , The internal combustion engine 1 includes several cylinders 4 , wherein the internal combustion engine 1 on the one hand fuel 5 and on the other hand charge air 6 is fed to the combustion, and wherein during the combustion of the fuel 5 resulting exhaust gas 7 from the internal combustion engine 1 is dissipated.

The exhaust charging system 2 includes an exhaust gas turbocharger 8th , the one compressor 9 and a turbine 10 includes. In the turbine 10 the exhaust gas turbocharger 8th the exhaust charging system 2 becomes the exhaust 7 Relaxed and used this energy used to the charge air 6 in the compressor 9 the exhaust gas turbocharger 8th to condense. In the compressor 9 compressed charge air is before feeding to the engine 1 via a charge air cooler 11 guided.

The exhaust aftertreatment system 3 includes a catalyst 12 , which is in particular an SCR catalyst. Exhaust gas, which is in the turbine 10 the exhaust gas turbocharger 8th has been relaxed, the exhaust aftertreatment over the catalyst 12 led, wherein the exhaust aftertreatment system 3 also via a bypass 13 over which bypasses the catalyst 12 Exhaust gas on the catalyst 12 can be passed.

Upstream of the catalyst 12 is a shut-off device 14 arranged. Further, downstream of the catalyst 12 a shut-off device 15 positioned. Another shut-off device 16 is in the bypass 13 arranged. Then, if exhaust over the bypass 13 bypassing the catalyst 12 should be performed, the shut-off devices 14 . 15 closed and the other shut-off device 16 of the bypass 13 will be opened. Then, on the other hand, if all the exhaust gas of the internal combustion engine 1 over the catalyst 12 the exhaust aftertreatment system 3 should be performed, the shut-off devices 14 . 15 opened and the other shut-off device 16 of the bypass 13 will be closed.

In the internal combustion engine 1 of the 1 it is preferably an internal combustion engine of a ship, is burned as a fuel heavy oil or residual oil. Ships will operate in areas or regions with different emission limits, some of which can already be met by internal combustion engine or internal combustion engine measures, so that then the catalyst 12 the exhaust aftertreatment system 3 , which is preferably an SCR catalyst, can be stopped or deactivated. It then becomes the upstream and downstream of the catalyst 12 positioned shut-off devices 14 . 15 closed to the catalyst 12 to separate from the exhaust flow, whereas then the other shut-off device 16 of the bypass 13 is opened. This is to avoid that exhaust gas in the area of the SCR catalyst 12 sulfuric acid from the exhaust gas in the area of the SCR catalyst 12 condense and so corrosion in the SCR catalyst 12 can cause.

As the upstream and downstream of the catalyst 12 positioned shut-off devices 14 . 15 not 100% close and therefore despite closed shut-off devices 14 . 15 an undefined or uncontrolled exhaust gas leakage into the SCR catalyst 12 can reach, is proposed according to the invention that, if when the internal combustion engine 1 the upstream and downstream of the catalyst 12 positioned shut-off devices 14 . 15 are closed, the catalyst 12 is acted upon with a defined or controlled exhaust partial stream.

In the embodiment of 1 , in which the exhaust gas first through the turbine 10 and only afterwards in the direction of the exhaust aftertreatment system 3 is performed, when the upstream and downstream of the catalyst 12 the exhaust aftertreatment system 3 positioned shut-off devices 14 . 15 are closed and the other shut-off device 16 of the bypass 13 open, over the catalyst 12 leading exhaust partial stream upstream of the turbine 10 the exhaust gas turbocharger 8th branched off, namely via a line 17 who is a thrush 18 assigned. This line 17 therefore branches upstream of the turbine 10 the exhaust gas turbocharger 8th from one the exhaust 7 from the cylinders 4 the internal combustion engine 1 in the direction of the turbocharger 8th leading exhaust pipe and leads the exhaust partial flow in the direction of the catalyst 12 ,

1 also shows a temperature sensor 24 which is an actual temperature in the catalyst 12 measures. Depending on this actual temperature, using the temperature sensor 24 is detected, the throttle can 18 be directed to the over the line 17 guided exhaust partial stream to regulate such that sets a desired target temperature in the catalyst, preferably a target temperature of at least 120 ° C, preferably a target temperature of at least 130 ° C, more preferably a target temperature of at least 200 ° C. ,

In the above with reference to 1 described embodiment is the catalyst 12 the exhaust aftertreatment device 3 seen in the exhaust gas flow direction downstream of the turbine 10 the exhaust gas turbocharger 8th positioned so that the exhaust 7 the internal combustion engine 1 first over the turbine 10 the exhaust gas turbocharger 8th and then via the catalyst 12 the exhaust aftertreatment system 3 can be performed, namely, when the shut-off devices 14 . 15 are open.

In contrast, shows 2 an embodiment in which the catalyst 12 the exhaust aftertreatment system 3 seen in the exhaust gas flow direction upstream of the turbine 10 the exhaust gas turbocharger 8th is arranged so that with open shut-off devices 14 . 15 the exhaust 7 the internal combustion engine 1 first over the catalyst 12 and only afterwards via the turbine 10 the exhaust gas turbocharger 8th to be led.

Then, if in the embodiment of 2 the shut-off devices 14 . 15 closed are the other shut-off device 16 of the bypass 13 is open, so if the exhaust itself to the catalyst 12 is to be passed, the catalyst 12 subjected to a partial exhaust gas flow, which is via the line 19 is guided, wherein in this line 19 preferably upstream of the catalyst 12 a shut-off device 20 and preferably downstream of the catalyst 12 a controllable throttle 21 is integrated.

Are the two shut-off devices 14 . 15 closed and is the other shut-off device 16 opened, so is shut-off device 20 opened to a defined or controlled exhaust partial flow not through the bypass 13 to lead, but over the catalyst 12 , This over the catalyst 12 guided partial exhaust gas flow is downstream of the turbine 10 the exhaust gas turbocharger 8th combined with the exhaust stream, which passes through the bypass 13 and the turbine 10 the exhaust gas turbocharger 8th to be led.

Also in the embodiment of 2 is using a temperature sensor 24 an actual temperature in the catalyst 12 detected and depending on the throttle 21 regulated, preferably such that in the catalyst 12 a desired target temperature of in particular at least 120 ° C, preferably of at least 130 ° C, more preferably of at least 200 ° C sets.

Further, depending on the with the help of the temperature sensor 24 detected actual temperature the shut-off device 20 controlled, namely closed or open, depending on either the partial exhaust gas flow over the catalyst 12 to release or block.

In the embodiments of the 1 and 2 is therefore when the catalyst 12 the exhaust aftertreatment system 3 should be shut down, so if the shut-off devices 14 . 15 are closed and the other shut-off device 16 of the bypass 13 is open, a partial exhaust gas flow over the catalytic converter 12 guided to keep it at a defined temperature. This can be avoided in particular that in the catalyst 12 Sulfuric acid condenses and so in the catalyst 12 causes corrosion-related aging. The partial exhaust gas flow over the catalyst 12 is guided, is about a throttle 18 respectively. 21 adjustable, in particular depending on the actual temperature of the catalyst 12 ,

3 shows a system of two internal combustion engines 1a . 1b , each with a Abgasaufladungssystem 2a . 2 B and an exhaust aftertreatment system, respectively 3a . 3b , The two internal combustion engines 1a . 1b of the 3 correspond in terms of their basic structure of the internal combustion engine 1 of the 1 Therefore, to avoid unnecessary repetition for the same components same reference numerals are used and to the comments on the embodiment of 1 is referenced.

Then, if both internal combustion engines 1a . 1b the plant of 3 can run, both internal combustion engines, as above in connection with the internal combustion engine of the 1 described, operated.

Then, if one of the internal combustion engines 1a . 1b the plant of 3 is stationary, so if no exhaust gas is produced in the same, the catalyst 12a . 12b the stationary internal combustion engine 1a . 1b with a partial exhaust gas flow of the current internal combustion engine 1b . 1a be charged. So shows 3 a line 22 with a shut-off device 23 , being over the line 22 Exhaust gas of the internal combustion engine 1a the catalyst 12b the exhaust aftertreatment system 3b the internal combustion engine 1b can be supplied, namely, when the shut-off device 23 is open.

Then, if so the internal combustion engine 1b of the 3 is stationary and in the same no exhaust gas, a partial exhaust gas flow over the line 22 starting from the internal combustion engine 1a towards the catalyst 12b the internal combustion engine 1b be guided to the catalyst 12b the exhaust aftertreatment system 3b the internal combustion engine 1b to keep at a defined temperature or to heat to a defined temperature. As a result, when the previously stationary internal combustion engine 1b should be put back into operation, immediately after commissioning a good exhaust aftertreatment quality in the SCR catalyst 12b be ensured because the same is then already heated to operating temperature or to a temperature near the operating temperature.

In 3 branches the line 22 , about which exhaust gas of the internal combustion engine 1a in the direction of the catalytic converter 12b the internal combustion engine 1b can be led by the line 17a off, over which, then, when running internal combustion engine 1a the catalyst 12a the same is stopped, a partial exhaust gas flow towards the catalyst 12a can be performed.

The regulation of over lines 17 . 19 Guided partial exhaust gas flow may be such that either a defined partial exhaust gas flow over the respective catalyst 12 is guided, or by periodically opening and closing the lines 17 . 19 a non-permanent exhaust partial flow is passed over the respective catalyst. This is done, as already stated, preferably such that an actual temperature in the catalyst 12 of at least 120 ° C, preferably of at least 140 ° C, more preferably of at least 200 ° C adjusts.

With reference to 3 described method in which, when an internal combustion engine 1b resting, the catalyst 12b the stationary internal combustion engine 1b with a partial exhaust gas flow of a running internal combustion engine 1a is applied, is used in particular when the sulfur content of the current internal combustion engine 1a burned fuel is less than 1200 ppm.

The invention is used in particular in internal combustion engines operated with excess air, preferably in marine diesel engines operated with heavy oil or residual oil.

Although the invention has been described in the context of SCR catalysts, the exhaust aftertreatment systems 3 . 3a . 3b also have other catalysts, such as catalysts, which are used for the decomposition of methane and / or formaldehyde and / or carbon monoxide and / or hydrocarbons. Also in this case, the invention can be used. However, particularly preferred is the use of the invention in exhaust aftertreatment systems whose catalysts are designed as SCR catalysts.

LIST OF REFERENCE NUMBERS

1, 1a, 1b

Internal combustion engine

2, 2a, 2b

Turbocharging System

3, 3a, 3b

aftertreatment system

4, 4a, 4b

cylinder

5, 5a, 5b

fuel

6, 6a, 6b

charge air

7, 7a, 7b

exhaust

8, 8a, 8b

turbocharger

9, 9a, 9b

compressor

10, 10a, 10b

turbine

11, 11a, 11b

Intercooler

12, 12a, 12b

catalyst

13, 13a, 13b

bypass

14, 14a, 14b

shut-off

15, 15a, 15b

shut-off

16, 16a, 16b

shut-off

17, 17a, 17b

management

18, 18a, 18b

pressure sensor

19

management

20

shut-off

21

throttle

22

management

23

shut-off

24, 24a, 24b

temperature sensor

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2015/158948 A1 [0006]

Claims (12)

Method for operating an internal combustion engine ( 1 ) with an exhaust gas charging system ( 2 ) and with an exhaust aftertreatment system ( 3 ), wherein the exhaust gas charging system ( 2 ) an exhaust gas turbocharger ( 8th ) with a turbine ( 10 ) and a compressor ( 9 ), wherein the exhaust aftertreatment system ( 3 ) a catalyst ( 12 ), upstream and downstream of the catalyst ( 12 ) positioned shut-off devices ( 14 . 15 ) and a bypass ( 13 ) with a further shut-off device ( 16 ) to the catalyst ( 12 ), and wherein to the head of an exhaust gas flow through the bypass ( 13 ) upstream and downstream of the catalyst ( 12 ) positioned shut-off devices ( 14 . 15 ) and the further shut-off device ( 16 ) of the bypass ( 13 ), characterized in that when the upstream and downstream of the catalyst ( 12 ) positioned shut-off devices ( 14 . 15 ) are closed and the further shut-off device ( 16 ) of the bypass ( 13 ), the catalyst ( 12 ) is acted upon by a partial exhaust gas stream. A method according to claim 1, characterized in that the exhaust gas first via a turbine ( 10 ) of the exhaust gas turbocharger ( 8th ) and then via the catalyst ( 12 ), wherein the closed shut-off devices ( 14 . 15 ) over the catalyst ( 12 ) guided exhaust partial stream upstream of the turbine ( 10 ) of the exhaust gas turbocharger ( 8th ) is diverted. A method according to claim 1, characterized in that the exhaust gas first via the catalyst ( 12 ) and then via a turbine ( 10 ) of the exhaust gas turbocharger ( 8th ), wherein the closed shut-off devices ( 14 . 15 ) over the catalyst ( 12 ) guided exhaust partial stream downstream of the turbine ( 10 ) of the exhaust gas turbocharger ( 8th ) in the over the turbine ( 10 ) led exhaust gas flow. Method according to one of claims 1 to 3, characterized in that the over the catalyst ( 12 ) is controlled so that the temperature in the catalyst is at least 120 ° C, preferably at least 130 ° C, more preferably at least 200 ° C. Method for operating a system with several internal combustion engines ( 1a . 1b ), characterized in that when an internal combustion engine ( 1a . 1b ) runs, the respective internal combustion engine ( 1a . 1b ) is operated according to one of claims 1 to 4. Method according to claim 5, characterized in that when an internal combustion engine ( 1a . 1b ), the catalyst ( 12a . 12b ) of the stationary internal combustion engine ( 1a . 1b ) with a partial exhaust gas flow of a running internal combustion engine ( 1a . 1b ) is applied. Internal combustion engine ( 1 ) with an exhaust gas charging system ( 2 ) and with an exhaust aftertreatment system ( 3 ), wherein the exhaust gas charging system ( 2 ) an exhaust gas turbocharger ( 8th ) with a turbine ( 10 ) and a compressor ( 9 ), wherein the exhaust aftertreatment system ( 3 ) a catalyst ( 12 ), upstream and downstream of the catalyst ( 12 ) positioned shut-off devices ( 14 . 15 ) and a bypass ( 13 ) with a further shut-off device ( 16 ) to the catalyst ( 12 ), characterized by a line ( 17 . 19 ) over which, if the upstream and downstream of the catalyst ( 12 ) positioned shut-off devices ( 14 . 15 ) are closed and the further shut-off device ( 16 ) of the bypass ( 13 ), the catalyst ( 12 ) can be acted upon with a partial exhaust gas stream. Internal combustion engine according to claim 7, characterized in that the exhaust gas first via a turbine ( 10 ) of the exhaust gas turbocharger ( 8th ) and then via the catalyst ( 12 ) is conductive, wherein the line ( 17 ) for closed shut-off devices ( 14 . 15 ) over the catalyst ( 12 ) guided exhaust partial stream upstream of the turbine ( 10 ) branches off. Internal combustion engine according to claim 7, characterized in that the exhaust gas first through the catalyst ( 12 ) and then via a turbine ( 10 ) of the exhaust gas turbocharger ( 8th ) is conductive, wherein the line ( 19 ) for closed shut-off devices ( 14 . 15 ) over the catalyst ( 12 ) partial exhaust gas flow downstream of the turbine ( 10 ) in an exhaust gas outlet of the turbine ( 10 ) opens. Internal combustion engine according to one of claims 7 to 9, characterized in that in the line ( 17 . 19 ) for closed shut-off devices ( 14 . 15 ) over the catalyst ( 12 ) guided exhaust partial flow an adjustable throttle ( 18 . 21 ) is integrated.  Internal combustion engine according to one of Claims 7 to 10, characterized by a control device for carrying out the method according to one of Claims 1 to 6. Plant of several internal combustion engines ( 1a . 1b ) according to one of claims 7 to 11, wherein via a line ( 22 ), of the the partial exhaust gas flow of a first internal combustion engine ( 1a ) leading line ( 17a ), the catalyst ( 12b ) a second internal combustion engine ( 1b ) with exhaust gas of the first internal combustion engine ( 1a ) can be acted upon.

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