KR20150044810A - Method for desulphating an exhaust gas retreatment system of an internal combustion engine - Google Patents

Abstract

The present invention relates to a method for re-desulfurizing the exhaust gas aftertreatment system of an internal combustion engine. The invention includes a step of testing the presence or absence of sulfate by allowing the exhaust gas aftertreatment system to measure one or more of sulfate indicated parameters. The invention includes the step which one or more relevant parameters related to the formation of sulfate in the area of exhaust gas aftertreatment system is detected and which determines whether they are within a range to cause the formation of sulfate. The invention includes the step which adjusts exhaust gas through actions for the inside or outside of an engine to make desulfurization start in the exhaust gas aftertreatment system and/or to make the parameters out of the range of values cause the formation of sulfate when the sulfate is present and/or the parameter within the value range is determined.

Description

TECHNICAL FIELD The present invention relates to a desulfurization method for an exhaust gas aftertreatment system of an internal combustion engine,

The present invention relates to a method for desulfurizing an exhaust gas after-treatment system of an internal combustion engine according to the preamble of claim 1.

The exhaustion regulations that are becoming more stringent are, for example, an oxidation catalytic converter, a particulate filter which is used for the reduction of nitrogen oxide emissions for an internal combustion engine used in this water transport means, And the use of exhaust aftertreatment systems including SCR catalytic converters.

In ships, most of them are used as distillate or residual oil containing high sulfur content. Sulfur can reach the exhaust aftertreatment system through combustion and at least locally deactivate the catalytic converter and / or the particulate filter in this exhaust aftertreatment system.

In the case of SCR catalytic converters used for NOx reduction, common elements are used as reducing agents to liberate ammonia, but ammonia forms ammonium sulfate and ammonium hydrogen sulphate together with the sulfur oxides contained in the exhaust gas, Can be deposited in the catalytic converter channels and thereby significantly increase the flow resistance of the catalytic converter.

In the case of fuels containing a high sulfur content, even the catalytic converter channels can be clogged, and as a result the exhaust gas back pressure in the exhaust gas aftertreatment system rises considerably, and the exhaust operation caused by the internal combustion engine is clearly raised, Not only is the output lost, but there is also the risk of damage to the internal combustion engine.

Even in the case of catalytic converters coated with precious metals, the local contamination of the catalytic converter through the sulfur oxides can occur because the sulfur reacts with the active components of catalytic converters such as platinum, palladium and aluminum, Lt; RTI ID = 0.0 >% < / RTI > conversion.

The higher the sulfur content in the fuel used, the faster the contamination of the catalytic converter or the rise in exhaust gas back pressure.

EP 1 173 693 B1 discloses a method and apparatus for monitoring an exhaust gas after-treatment system of an internal combustion engine. In the case of the known method, the oxidation catalytic converter provided in the exhaust gas aftertreatment system is monitored in relation to its performance capability, and more precisely, upstream of the catalytic converter and downstream thereof in the case of particulate filter regeneration to be initiated Is monitored through evaluation of the temperature behavior.

It is an object of the present invention to provide a method for desulfurizing an exhaust gas aftertreatment system of an internal combustion engine which is provided in an exhaust gas aftertreatment system so that the devices for posttreatment the exhaust gas can be maintained while being regenerated It is on.

The present invention has the features specified in claim 1 for solving the above problems. Preferred configurations of the present invention are described in the appended claims.

The present invention relates to a method for desulfurizing an exhaust gas aftertreatment system of an internal combustion engine,

- the exhaust aftertreatment system is checked for the presence or absence of sulfate through the measurement of one or more indication parameters;

- one or more relevant parameters related to sulfate formation in the region of the exhaust aftertreatment system are detected in such a way that it is added or replaced such that it is determined whether this parameter is within a value range causing sulphate formation,

And / or when the parameters within the value range are determined, the desulfurization is initiated in the exhaust gas aftertreatment system and / or the parameter is out of the range of values causing sulphate formation The step of causing the exhaust gas to be appropriately adjusted through the measures inside or after the engine

Wherein the desulfurization is carried out in the presence of the catalyst.

In other words, the present invention is one or more indicating parameters for the presence of sulfate in the exhaust aftertreatment system, i. E. Exhaust gas indicating the presence of sulfate in the exhaust aftertreatment system and formed by, for example, Wherein the at least one indication parameter, which may be back pressure, is monitored. The exhaust backpressure can be detected by measurement techniques in the entire flow region of the exhaust aftertreatment system because the stagnation pressure against the internal combustion engine increases as the desulfurization progresses in the region of the catalytic converter of the exhaust aftertreatment system Because it increases with increasing deposition of sulfate. In other words, the pressure measurement can be initiated, for example, in the region of the inlet of the catalytic converter.

In accordance with the method according to the present invention, parameters related to the formation of sulfates in the region of the exhaust aftertreatment system are detected in such a way that they are added to or replaced in the detection of parameters indicative of the presence of deposits in the exhaust aftertreatment system, It is determined whether this parameter is within a value range causing sulphate formation. The parameter may be, for example, the temperature on the working surface of the catalytic converter provided in the region of the exhaust aftertreatment system, the catalytic converter may be an SCR catalytic converter, or may have an operating surface doped, for example, Can be another catalytic converter used for reduction.

If the measurement of the indicator parameter indicates the presence of sulfate in the exhaust aftertreatment system and / or if the associated parameter is within a value range causing sulfate formation, desulfurization in the exhaust aftertreatment system is initiated, and / The exhaust gas of the internal combustion engine is appropriately adjusted through internal or after-engine measures so that the value falls outside the value range causing the sulfate formation.

For example, for the decomposition of ammonium sulphate and / or ammonium sulphate or sulphate with the active components of the catalytic converter, with the temperature range required for regeneration desulfurization in the exhaust aftertreatment system, The necessary temperature range can be achieved.

It is also possible, through the measures described above, to ensure that the operation of the internal combustion engine is ensured while observing the exhaust gas regulations, that is, for example, measures within the engine are intended to raise the temperature of the exhaust gas, And / or the pressure range is achieved.

This may be a temporary measure aimed at restoring the reactivity of the catalytic converter by preventing the sulphate deposited in the catalytic converter from decomposing but not reaching a temperature range exceeding the temperature stability of the catalytic converter in the catalytic converter .

The achievement of the activation temperature required for the regeneration of the catalytic converter can be measured, for example, via a temperature sensor at the catalytic converter inlet, but may, however, be determined by a calculation model under evaluation of the operating data required for operation of the internal combustion engine.

In order to bring about the required activation temperature, for example in the region upstream of the catalytic converter, fuel can be injected which provides the reducing agent required in the form of hydrocarbons in the catalytic converter. Such measures are actions initiated after the engine, that is, downstream of the internal combustion engine with respect to the exhaust gas.

It is also provided in accordance with the present invention, in a complementary or alternative manner, to achieve measures within the engine for achieving an activation temperature that causes desulfurization in the region of the exhaust gas catalytic converter. For this purpose, basically, even if the internal combustion engine is operating in the normal low load range, all measures within the engine that achieve the activation temperature at the correspondingly low exhaust gas temperature are suitable.

This may be, for example, an advancing of the starting point of the fuel injection into one or more operating cylinders of the internal combustion engine, that is to say that the fuel injection is displaced in the advancing direction, do. If the injection of fuel starts with a relatively more advanced start and the injection period is extended significantly, the total amount of fuel injected increases and the hydrocarbons in the exhaust gas become enriched, and therefore the activation temperature required for regeneration in the catalytic converter connected downstream Can be achieved. In addition, an oxidation catalytic converter can be connected upstream of the exhaust gas catalytic converter in terms of flow technology, and this oxidation catalytic converter provides heat necessary for regeneration of the catalytic converter by exothermic conversion of additional hydrocarbons.

It is also possible to perform one or more post-fuel injections in one or more operating cylinders of the internal combustion engine, in a manner replenished or supplemented therewith. The two measures described above cause a temperature rise of the exhaust gas of the internal combustion engine, whereby a regeneration activation temperature for desulfurizing the exhaust gas catalytic converter can be achieved.

In order to provide the hydrocarbon as a reducing agent for the regeneration of the catalytic converter, at least one or more measures may be taken to lower the combustion efficiency in the at least one operating cylinder of the internal combustion engine, It is possible to intentionally lower the fuel combustion so as to enrich the exhaust gas of the internal combustion engine. This can be done intermittently during the regeneration process of the catalytic converter, since it is a temporary measure, for example, the temperature monitoring of the catalytic converter is possible, and the action is to ensure that the measured temperature in the catalytic converter is close to the lower limit of the activation temperature When it starts.

Thus, the combustion is reduced only until the activation temperature for the desulfurization is achieved, then back to normal, and again the temperature in the catalytic converter approaches the lower limit of the activation temperature for desulfurization, The decrease in combustion is resumed only when it is reduced.

In accordance with the present invention there is provided a method for reducing the exhaust gas volume flow in a manner that replaces or replaces the intake air flow supplied to at least one operating cylinder of the internal combustion engine, . As a result, an exhaust gas containing more non-combusted hydrocarbon components is provided, which can be supplied, for example, to an oxidation catalytic converter connected upstream of the exhaust gas catalytic converter, whereby the desulfurization of the exhaust gas after- A temperature rise of the exhaust gas sufficient to achieve the activation temperature for the exhaust gas is achieved.

In this way, when an SCR catalytic converter is included in the exhaust aftertreatment system, ammonium sulfate and ammonium hydrogen sulfate can be decomposed, and the catalytic converter can be operated in such a way that the exhaust gas temperature is controlled by the above- And is then raised to an activation temperature of about 350 degrees, thereby achieving its original performance capability again.

In this way, the particulate filter provided in the exhaust aftertreatment system can be regenerated by the oxidation catalytic converter connected upstream of the particulate filter. The oxidation catalytic converter can also be used, for example, to achieve an exhaust gas temperature of 450 to 550 degrees Celsius required for regeneration of noble metal catalytic converters.

By means of the measures in the engine described above, an exhaust gas to be expressed as a richer exhaust gas is attained and is sufficient for desulfurization in the catalytic converter of the exhaust gas aftertreatment system by this exhaust gas, Lt; RTI ID = 0.0 > temperature < / RTI >

The process according to the invention can therefore operate the internal combustion engine used for driving the water-conveying means while operating the distillation oil or residual flow, which usually contains a high sulfur content, so as to comply with the respective exhaust gas regulations.

Claims (7)

A method for desulfurizing an exhaust gas aftertreatment system of an internal combustion engine,
- the exhaust aftertreatment system being tested for the presence or absence of sulfate through the measurement of one or more indication parameters;
- one or more relevant parameters related to sulfate formation in the region of the exhaust aftertreatment system are detected in such a way that it is added or replaced such that it is determined whether the parameter is within a value range causing sulphate formation ,
- desulfurization is initiated in the exhaust gas aftertreatment system and / or when the parameters are within the value range, and / or the parameter is out of the range of values causing the sulfate formation , Causing the exhaust gas of the internal combustion engine to be appropriately adjusted through measures internal to the engine or after the engine
Wherein the desulfurization of the exhaust gas aftertreatment system is performed. 2. A method according to claim 1, characterized in that, for the measurement of the indication parameter, the exhaust gas back pressure produced by the exhaust gas after-treatment system is detected and the measures are carried out if the exhaust gas back- A method of desulfurization of a system. 3. The method according to claim 1 or 2, wherein, for the measurement of the relevant parameter, if the temperature of the exhaust gas in the region of the exhaust aftertube system is detected and the temperature is within a value range causing sulphate formation, Is carried out in the exhaust gas after-treatment system. 3. The desulfurization method according to claim 1 or 2, wherein the related parameter can be determined by a calculation model based on operating parameters of the internal combustion engine. 5. The method according to any one of claims 1 to 4, wherein the activation temperature causing desulfurization in the region of the exhaust gas catalytic converter of the exhaust aftertreatment system comprises the following steps:
An action to advance the starting point of fuel injection in one or more operating cylinders of the internal combustion engine,
- performing at least one post-fuel injection in one or more operating cylinders of the internal combustion engine,
- an action of introducing fuel upstream of said exhaust gas catalytic converter,
- implementing one or more measures to temporarily reduce combustion efficiency in one or more operating cylinders of the internal combustion engine, and
Among the measures to reduce the intake air flow supplied to one or more operating cylinders of the internal combustion engine to reduce the exhaust gas volume flow in the condition that the fuel is supplied substantially constantly to the operating cylinder
≪ / RTI > is accomplished by one or more actions. 6. The desulfurization method of an exhaust aftertreatment system according to any one of claims 1 to 5, wherein the exhaust aftertreatment system comprises at least one SCR catalytic converter and / or a particulate filter. 7. The desulfurization method of an exhaust aftertreatment system according to any one of claims 1 to 6, characterized in that the internal combustion engine operates in accordance with the diesel principle and is provided as a drive engine for water transport means.