KR102083689B1 - Method for the exhaust gas retreatment on an internal combustion engine and internal combustion engine - Google Patents

Abstract

Exhaust from the internal combustion engine 10, in particular from an internal combustion engine operated with heavy oil, comprising at least one exhaust gas turbocharge through at least one exhaust gas turbocharger 13 and exhaust gas purification through the SCR catalytic converter 14. In the gas reprocessing method, an SCR catalytic converter 14 is disposed upstream of the or each exhaust gas turbocharger 13 in the flow direction of the exhaust gas, and the SCR catalytic converter 14 in the flow direction of the exhaust gas. ) Sulfur dioxide is oxidized downstream and upstream of the or each exhaust gas turbocharger 13 to form sulfur trioxide, and sulfur trioxide downstream of the or each exhaust gas turbocharger 13 in the flow direction of the exhaust gas. Condensation forms sulfuric acid and is removed from the exhaust gas as sulfuric acid.

Description

Reprocessing method of exhaust gas in internal combustion engine and internal combustion engine {METHOD FOR THE EXHAUST GAS RETREATMENT ON AN INTERNAL COMBUSTION ENGINE AND INTERNAL COMBUSTION ENGINE}

The present invention relates to an exhaust gas reprocessing method in an internal combustion engine according to the preamble of claim 1. The invention also relates to an internal combustion engine according to the preamble of claim 11.

DE 10 2004 027 593 A1 discloses an internal combustion engine in which one or two stages of exhaust gas charging and exhaust gas purification by an SCR catalytic converter are performed. In the case of a single exhaust gas charging, the SCR catalytic converter according to the prior art is arranged downstream of the turbine of the exhaust gas turbocharger or upstream of the turbine of the exhaust gas turbocharger. In the case of two stage exhaust gas charging with two exhaust gas turbochargers, the SCR catalytic converter according to the prior art is connected between two turbines of two exhaust gas turbochargers. In addition, the prior art already discloses bypassing the SCR catalytic converter via a bypass line to direct the exhaust gas through the SCR catalytic converter in the direction of the turbine of the exhaust gas turbocharger disposed downstream of the SCR catalytic converter. The exhaust gas flow through the bypass line can be regulated by the regulating device.

Although it is already possible to reduce nitrogen oxides, in particular nitrogen monoxide and nitrogen dioxide, in the exhaust gas by the SCR catalytic converter in a defined manner, there is an additional need to reduce SO ₂ emissions, especially in internal combustion engines operated with heavy oil.

Starting from this, the object of the present invention is to focus on a new type of method and a new type of internal combustion engine for exhaust gas reprocessing in an internal combustion engine.

The problem is solved by the method according to claim 1. According to the invention, a catalytic converter for oxidizing sulfur dioxide is installed in the exhaust gas of an exhaust gas turbocharged internal combustion engine upstream of the exhaust gas turbocharger, and the or each exhaust gas turbocharger as viewed in the flow direction of the exhaust gas. Downstream of the condensation, sulfur trioxide is condensed to form sulfuric acid and removed from the exhaust gas as sulfuric acid and / or sulfate.

In order to reduce SO ₂ emissions, in particular in internal combustion engines operating with heavy oils, according to the invention two measures, on the one hand, the oxidation of sulfur oxides upstream of the exhaust gas charging to form sulfur trioxide, and on the other hand Downstream of the supercharge, a condensation of sulfur trioxide to form sulfuric acid is used in combination. The oxidation of sulfur dioxide to sulfur trioxide is by means of an SO ₂ oxidation catalytic converter, in which case the exhaust gas at high temperature and high pressure when oxidizing sulfur dioxide to sulfur trioxide because the oxidation takes place in the oxidation catalytic converter upstream of the exhaust gas charge. SO ₂ oxidation is thus accelerated and proceeded under optimum operating conditions, in particular without the need to preheat the exhaust gas by means of a suitable preheating device. Further, downstream of the exhaust gas charging, sulfur trioxide is condensed to form sulfuric acid. In this case, condensation from sulfur trioxide to sulfuric acid occurs at a temperature much lower than oxidation from nitrogen oxides to nitrogen dioxide due to the enthalpy slope through the above or each turbine of the exhaust gas charging, so that sulfur dioxide from sulfur trioxide to sulfur dioxide downstream of the exhaust gas charging Condensation can also be effected optimally and accordingly.

According to the invention, the process can be combined with an SCR catalytic converter in such a way that the SCR catalytic converter is installed upstream of the SO ₂ oxidation catalytic converter.

Preferably, ammonia and / or ammonia precursor material which is converted into ammonia in the exhaust gas is introduced into the exhaust gas upstream of the SCR catalytic converter. Introducing ammonia and / or ammonia precursor material into the exhaust gas upstream of the SCR catalytic converter allows for efficient conversion of nitrogen oxides within the SCR catalytic converter.

According to a first preferred refinement of the invention, the ammonia and / or ammonia precursor material has a feed ratio of NH ₃ / NO _x > 1 and thus downstream of the SCR catalytic converter, ammonia is introduced into the exhaust gas so that it is used in the neutralization of sulfuric acid. According to a second preferred refinement of the invention, upstream of the SCR catalytic converter and downstream of the position where the ammonia and / or ammonia precursor material is introduced into the exhaust gas, the exhaust gas partial flow branches and the exhaust gas partial flow is diverted. Ammonia can be fed to sulfuric acid downstream of sulfuric acid condensation or to the exhaust gas upstream of sulfuric acid condensation, which is used for neutralization of sulfuric acid. With two preferred refinements, it is possible to neutralize the sulfuric acid produced during condensation, especially with the ammonia required in the SCR catalytic converter. In order to neutralize the sulfuric acid produced during condensation, a separate basic component is not necessary.

Preferably the exhaust gas of the exhaust gas partial stream is guided through an additional SCR catalytic converter and / or through a hydrolysis catalytic converter. On the one hand this ensures quantitative decomposition of the NH ₃ precursor material in the hydrolysis catalytic converter and on the other hand the nitrogen oxides are released through the exhaust gas passage which contains NH ₃ which is necessary for the neutralization of sulfuric acid.

An internal combustion engine according to the invention is defined in claim 12.

Preferred refinements of the invention are set forth in the dependent claims and the following description. Embodiments of the present invention are described with reference to the drawings, but are not limited thereto.

1 is a schematic diagram of a turbocharged internal combustion engine according to a first embodiment of the present invention;
2 is a schematic diagram of a turbocharged internal combustion engine according to a second embodiment of the present invention;
3 is a schematic diagram of a turbocharged internal combustion engine according to a third embodiment of the invention;
4 is a schematic diagram of a turbocharged internal combustion engine according to a fourth embodiment of the invention;

The present invention relates to an internal combustion engine, in particular a marine diesel engine operated with heavy oil. The invention also relates to an exhaust gas reprocessing method in the internal combustion engine.

The specialty of an internal combustion engine operated with heavy oil is that the fuel used by the internal combustion engine, ie heavy oil, has a high sulfur content. As exhaust gas regulations become increasingly stringent, there is a need to further reduce sulfur oxide emissions. The present invention proposes measures or features that can effectively reduce SO ₂ emissions in heavy oil operated internal combustion engines.

1 shows a first embodiment according to the invention comprising an engine 11 with a plurality of cylinders 12, exhaust gas charging via an exhaust gas turbocharger 13 and exhaust gas purification via an SCR catalytic converter 14. The internal combustion engine 10 is shown.

In the combustion of fuel, in particular heavy oil, the exhaust gases generated in the cylinder 12 of the engine 11 are first passed through the SCR catalytic converter 14 for exhaust gas purification and subsequently for exhaust gas turbocharger 13 for energy recovery. Energy obtained at the time of expansion of the exhaust gas in the turbine 15 of the exhaust gas turbocharger 13 is supplied to the exhaust gas turbo for the combustion of fuel in the cylinder 2 It is used to compress in the region of the compressor 16 of the supercharger 13.

Ammonia and / or ammonia precursor material is introduced into the exhaust gas upstream of the SCR catalytic converter 14, which may be, for example, an aqueous urea solution. This ammonia precursor material is converted in the exhaust gas to form ammonia, and the SCR catalytic converter 14 requires ammonia as the reducing agent in the conversion of nitrogen oxides.

1 shows an ammonia generator 17, in which ammonia is formed. In FIG. 1 upstream of the SCR catalytic converter 14, ammonia is introduced into the exhaust gas leaving the cylinder 12 of the engine 11.

According to the invention the exhaust gas turbocharger 13 oxidizes sulfur dioxide of the exhaust gas to nitrogen dioxide downstream of the SCR catalytic converter 14 and upstream of the turbine 15 in the flow direction of the exhaust gas. That is, it is oxidized by the SO ₂ oxidation catalytic converter 18 arranged downstream of the SCR catalytic converter 14 and upstream of the turbine 15 of the exhaust gas turbocharger 13 in the flow direction of the exhaust gas according to FIG. 1. Let's do it. Due to this positioning of the SO ₂ oxidation catalytic converter, SO ₂ oxidation can be effected accordingly at high temperatures and high pressures, and preheating of the exhaust gas upstream of the SO ₂ oxidation catalytic converter 18 is not necessary.

Furthermore, according to the invention sulfur trioxide is condensed with sulfuric acid downstream of the exhaust gas turbocharger 13 in the flow direction of the exhaust gas, ie downstream of the turbine 15 of the exhaust gas turbocharger 13. To this end, an H ₂ SO ₄ condenser 19 is arranged downstream of the exhaust gas turbocharger 13, ie downstream of the turbine 15 of the exhaust gas turbocharger 13 according to FIG. 1. The exhaust gas leaving the turbine 15 of the exhaust turbocharger 13 is fed to the H ₂ SO ₄ condenser 19, in which case the H ₂ SO ₄ condenser is on the one hand the exhaust gas and on the other hand sulfuric acid. To this end, sulfuric acid resulting from the condensation of sulfur trioxide in the H ₂ SO ₄ condenser 19 collects in the vessel 20.

Due to the enthalpy slope through the turbine 15, condensation occurs in the H ₂ SO ₄ condenser 19 at a much lower temperature than oxidation in the SO ₂ oxidation catalytic converter. Oxidation in the SO ₂ oxidation catalytic converter 18 and condensation in the H ₂ SO ₄ condenser 19 take place at optimal process conditions.

Here, in the region of the SO ₂ oxidation catalytic converter 18, vanadium V and / or potassium K and / or sodium Na and / or cesium Cs and / or iron Fe and / or cerium Ce and optionally these elements It is pointed out that oxides can be used.

The amount of vanadium in the active ingredient is greater than 5%, preferably greater than 7%, more preferably greater than 9%,

According to a preferred refinement of the invention, the sulfuric acid produced during condensation is neutralized, in which case salts of sulfuric acid are formed.

To this end, in the embodiment of FIG. 1, the ammonia and / or ammonia precursor material has a feed ratio NH ₃ / NO _x > 1, whereby ammonia is given in the exhaust gas downstream of the SCR catalytic converter 14 and the ammonia is H It can be introduced into the exhaust gas so that it can be used for the neutralization of sulfuric acid produced in the region of the ₂ SO ₄ condenser 19.

Alternatively, the exhaust gas partial flow diverges through the bypass 21 upstream of the SCR catalytic converter 14 and downstream of the position where the ammonia generated in the ammonia generator 17 is introduced into the exhaust gas according to FIG. 2. And guided past the turbine 15 of the SCR catalytic converter 14, the SO ₂ oxidation catalytic converter 18 and the exhaust gas turbocharger 13, so that the exhaust gas partial flow is upstream of the H ₂ SO ₄ condenser 19. The sulfuric acid may be neutralized in such a way that it is mixed with the exhaust gas at. In this case, ammonia is given in the exhaust gas partial stream which can in turn be used for the neutralization of sulfuric acid. In this regard, the exhaust gas of the exhaust gas partial flow guided through the bypass 21 may be guided through an additional SCR catalytic converter 22.

3 shows an exhaust gas partial flow branched from the exhaust gas stream upstream of the SCR catalytic converter 14 via bypass 21 and downstream of the position where ammonia generated in the ammonia generator 17 is introduced into the exhaust gas. The exhaust gas of is also shown a modification of the present invention, which is used for neutralization of sulfuric acid generated in the region of the H ₂ SO ₄ condenser 19. However, in FIG. 3, unlike FIG. 2, the exhaust gas partial stream is supplied to the sulfuric acid or sulfuric acid circuit and does not mix with the exhaust gas flow off the turbine 15 upstream of the H ₂ SO ₄ condenser 19. In the variant of FIG. 3, a separate SCR catalytic converter 22 may optionally be assigned to the bypass 21 to direct the exhaust gas of the exhaust gas partial flow through the SCR catalytic converter.

FIG. 4 shows a variant of the invention in which an ammonia precursor material, not ammonia, is introduced into the exhaust gas downstream of the engine 11 and the ammonia precursor material is converted in the exhaust gas to form ammonia. The ammonia precursor material may be, for example, an aqueous urea solution, which is converted in the exhaust gas to form ammonia, carbon dioxide and water vapor.

In the variant of FIG. 4, as in the variant of FIG. 3, upstream of the SCR catalytic converter 14 and downstream of the location where the ammonia precursor material is introduced into the exhaust gas, the exhaust gas portion through the bypass 21. The flow is branched and the exhaust gas partial flow is guided through the hydrolysis catalytic converter 23 in FIG. 4 to accelerate or improve the conversion of the ammonia precursor material to ammonia.

By means of a controllable or adjustable choke 24, the exhaust gas partial flow guided through the bypass 21 can be regulated. Guided through the hydrolysis catalytic converter 23, via the control 21 or by the controllable chokes 25 and 26, the SCR catalytic converter 14, the SO ₂ oxidation catalytic converter 18 and The amount of partial flow fed through the exhaust gas turbocharger 13 and returned to the main stream upstream of the SCR catalytic converter 14 may be adjusted.

Common to all the illustrated embodiments is a SO ₂ oxidation catalytic converter downstream of the SCR catalytic converter 14 and upstream of the turbine 15 of the exhaust gas turbocharger 13 in a heavy oil operated turbocharged internal combustion engine 10. that will 18 is provided, wherein the SO ₂ oxidation is accelerated at high temperature and high pressure by the SO ₂ oxidation catalytic converter can be carried out.

Further, in all embodiments, the H ₂ SO ₄ condenser is installed downstream of the turbine 15 of the exhaust gas turbocharger 13 so that sulfur trioxide is condensed to form sulfuric acid and discharged in the form of sulfuric acid.

Preferably, the generated sulfuric acid is neutralized by the ammonia required as reducing agent in the region of the SCR catalytic converter 14.

As mentioned above, the ammonia used for neutralization of sulfuric acid may be mixed with the exhaust gas upstream of the H ₂ SO ₄ condenser 19 and downstream of the turbine 15 or the H ₂ SO ₄ condenser 19 Downstream), and may be mixed with sulfuric acid.

Since ammonia can be provided at a feed ratio> 1, an amount sufficient to neutralize sulfuric acid in the exhaust gas downstream of the SCR catalytic converter 14 and upstream of the H ₂ SO ₄ condenser 19 without the need for a bypass line. Of ammonia is provided.

On the other hand, the exhaust gas partial flow can be diverted from the exhaust gas main stream by the bypass line 21 upstream of the SCR catalytic converter 14, and ammonia and / or ammonia precursor material is included in the exhaust gas partial flow. This provides ammonia used for the neutralization of sulfuric acid.

In a particularly preferred embodiment (see FIGS. 2-4), the exhaust gas partial flow guided through the bypass line 21 past the SCR catalytic converter 14, the SO ₂ oxidation catalytic converter 18 and the turbine 15. Guided by SCR catalytic converter 22 and / or hydrolysis catalytic converter 23 in the region of this bypass line 21. Through the hydrolysis catalytic converter 23, the production of ammonia in the exhaust gas can be supported. Nitrogen oxides in the exhaust gas partial stream may be reduced through a separate SCR catalytic converter 22 of the bypass 21.

When the SCR catalytic converter 22 is installed in the bypass line 21, neutralization of sulfuric acid H ₂ SO ₄ in ammonium sulfate (NH ₄ ) ₂ SO ₄ downstream of the SCR catalytic converter 22 also for the exhaust gas partial flow. A feed ratio of> 1 in the exhaust gas partial stream is applied to provide sufficient ammonia NH ₃ for.

10 internal combustion engine
11 engine
12 cylinder
13 exhaust gas turbocharger
14 SCR catalytic converter
15 turbines
16 compressor
17 Ammonia Generator
18 SO ₂ Oxidation Catalytic Converter
19 H ₂ SO ₄ condenser
20 containers
21 bypass
22 SCR catalytic converter
23 hydrolysis catalytic converter
24, 25, 26 chokes

Claims (17)

A method of reprocessing an exhaust gas in an internal combustion engine comprising at least one exhaust gas turbocharge and at least one exhaust gas turbocharger through at least one exhaust gas turbocharger,
The exhaust gas generated in the cylinder of the internal combustion engine is guided to an SO ₂ oxidation catalytic converter installed upstream of the exhaust gas turbocharger, and oxidation of sulfur dioxide occurs in the SO ₂ oxidation catalytic converter,
The exhaust gas is then guided to an H ₂ SO ₄ condenser disposed downstream of the exhaust gas turbocharger or each exhaust gas turbocharger in the flow direction of the exhaust gas, wherein sulfur trioxide condenses in the H ₂ SO ₄ condenser. To form sulfuric acid, which is removed from the exhaust gas as sulfuric acid, sulfate, or sulfuric acid and sulfate,
An SCR catalytic converter for Selective Catalytic Reduction (SCR) is installed upstream of the SO ₂ oxidation catalytic converter for the oxidation of sulfur dioxide,
Upstream of the SCR catalytic converter, ammonia, an ammonia precursor material which is converted into ammonia in the exhaust gas, or ammonia and ammonia precursor material is introduced into the exhaust gas,
An exhaust gas partial flow is branched upstream of the SCR catalytic converter, and via the exhaust gas partial flow, ammonia can be supplied to the sulfuric acid downstream of sulfuric acid condensation, the ammonia being used for neutralization of the sulfuric acid. Exhaust gas reprocessing method. delete delete The ammonia, the ammonia precursor material, or the ammonia and the ammonia precursor material have a feed ratio of NH ₃ / NO _x > 1, so that ammonia is introduced into the exhaust gas downstream of the SCR catalytic converter. And into the exhaust gas in such a way that it is given to be used for neutralization of the sulfuric acid. delete The exhaust gas partial flow is branched upstream of the SCR catalytic converter, the ammonia may be supplied to the exhaust gas upstream of sulfuric acid condensation via the exhaust gas partial flow, wherein the ammonia is Exhaust gas reprocessing method, characterized in that it is used for neutralization. 7. The method of claim 1 or 6, wherein the exhaust gas of the exhaust gas partial flow is guided through an additional SCR catalytic converter. 7. The method of claim 1 or 6, wherein the exhaust gas of the exhaust gas partial stream is guided through a hydrolysis catalytic converter for hydrolysis of the ammonia precursor material. 7. At least one element according to any one of claims 1, 4 and 6, selected from the group of vanadium, sodium, potassium, cerium, iron, cesium or oxides thereof as active ingredient for SO ₂ oxidation catalytic converter. Exhaust gas reprocessing method characterized in that it is used. 10. The method of claim 9, wherein the amount of vanadium in the active ingredient is greater than 5%. An internal combustion engine comprising at least one exhaust gas turbocharger and at least one sulfur removal device of the exhaust gas through at least one exhaust gas turbocharger 13,
An SO ₂ oxidation catalytic converter 18 for the oxidation of sulfur dioxide is provided upstream of the exhaust gas turbocharger 13, and downstream of the exhaust gas turbocharger or each exhaust gas turbocharger in the flow direction of the exhaust gas. By placing the H ₂ SO ₄ condenser 19, sulfur trioxide is condensed in the form of sulfuric acid and removed from the exhaust gas,
SCR catalytic converter 14 for selective catalytic reduction is installed upstream of the SO ₂ oxidation catalytic converter for oxidation of sulfur dioxide,
Upstream of the SCR catalytic converter 14, ammonia or ammonia precursor material that can be converted into ammonia in the exhaust gas can be introduced into the exhaust gas,
A bypass line 21 is provided which branches in front of the SCR catalytic converter 14, the bypass line 21 being downstream of the exhaust gas turbocharger 13 or each exhaust gas turbocharger 13. And into the stream of exhaust gas upstream of the H ₂ SO ₄ condenser (19). delete delete delete 12. The bypass line (21) according to claim 11 is provided with a bypass line (21) branching in front of said SCR catalytic converter (14), said bypass line (21) being sulfuric acid downstream of said H ₂ SO ₄ condenser (19). An internal combustion engine characterized by leading through. 12. An internal combustion engine according to claim 11, wherein an additional SCR catalytic converter (22) is arranged in the bypass line (21). 12. An internal combustion engine according to claim 11, characterized in that a hydrolysis catalytic converter (23) is arranged in the bypass line (21).

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