Übersetzung für "Lean combustion" in Deutsch

Nitrogen oxides catalysts were developed specifically for the exhaust gas treatment of lean-burn internal combustion engines.

Nitrogen oxide storage catalysts were developed specifically for the treatment of exhaust gases from lean operated internal combustion engines.

Diesel engines and lean burn gasoline engines belong to the group of lean operated internal combustion engines.

This makes possible the maximum thermal efficiency of an unthrottled, lean gasoline combustion process and also minimized exhaust-gas emissions.

The lean combustion precludes the generation of nitrogen oxide by merely engine-related measures directly on combustion.

The lean combustion concurrently causes the combustion reaction to approach its lean extinguishing limit.

This may be considerable in the case of lean-operated internal combustion engines, particularly diesel engines.

The hydrocarbons in the lean combustion chamber regions are discharged through the opening exhaust valve.

The lean combustion is often unstable, however, and increasingly tends to form combustion oscillations.

However, this lean combustion also necessitates a low flame temperature and makes it difficult to stabilize the flame.

However, lean premix combustion is very susceptible to combustion instabilities, especially to thermoacoustic pulsations.

The lean combustion method has the following process steps after an expansion phase (zero point of the X-axis):

The present invention relates to a method for the treatment of exhaust gas of lean-burn combustion engines.

By admixture of air, the mixture is transferred into a lean combustion state, characterised by an excess of air.

On the other hand, the "lean premix combustion" leads to poor combustion efficiency in the lower load range of a combustion chamber and to correspondingly high NOx, CO and UHC emissions.

The "lean premix combustion" leads to a poor combustion efficiency in the low load range of a combustion chamber and to correspondingly high NOx, CO and HC emissions.

This filling should take place without starting the internal combustion engine in order to prevent catalyst damage due to lean combustion at the beginning of operation of the internal combustion engine.

Lean premixed combustion is a common method of achieving low pollutant emissions, in particular nitric-oxide emissions, in the combustion of fuels having a low content of nitric-oxide compounds.

With the long spark duration resulting from the use of alternating voltage, however, the time interval t 2 can be extended, since even after the value has gone above the upper, lean ignition limit, combustion chamber flow briefly forces ignitable mixture components between the electrodes, and these can be encountered by the long-duration sparks.

Compared thereto, even greater reductions can be achieved with the pre-mixed lean combustion applied in stationary gas turbines.

In a known combustion chamber arrangement according to German Letters Patent 43 18 405, a reduction of the nitrogen oxide formation is enabled with pre-mixed lean combustion without risk of self-ignition in a pre-mixing path in that the fuel is injected into a pre-mixing chamber fashioned essentially straight that tangentially discharges into an essentially rotationally-symmetrically fashioned combustion chamber, as a result whereof a creation of twist is achieved when the mixture flows in.

Whereas the purification of exhaust gases from stoichiometrically operated internal combustion engines has achieved a very high level, there are still considerable problems with conversion of nitrogen oxides emissions from lean operated internal combustion engines.

Due to lean combustion, low NOx emissions can be expected, so that the admixing of the steam quantity used beforehand for cooling purposes is, on the one hand, to be effected separately from this combustion and, on the other hand, is to be effected after complete burn-out has been effected, so that the CO emissions and UHC emissions can thus also be minimized.

A process for lowering levels of nitrogen oxides in the exhaust gas stream of lean burn combustion engines comprising catalytically reducing said nitrogen oxides in the presence of a reduction catalyst which reduces nitrogen oxides to nitrogen, using the hydrocarbons and carbon monoxide also present in the exhaust gas as reducing agents, measuring exhaust gas temperature at a point in said stream upstream from said catalyst, and upstream from said point injecting fresh air into the exhaust gas stream to control the temperature of the exhaust gas upstream from the reduction catalyst to a value at which the conversion rate for the nitrogen oxides into nitrogen as the exhaust gas passes in contact with said reduction catalyst is at its maximum to thereby yield nitrogen, water and carbon dioxide in the exhaust gas.

Accordingly, one object of the invention is, in the case of a method for operating a gas turbine group of the type mentioned at the start, is to provide a novel way of ensuring lean combustion with low emissions and to make it possible to have a stable flame at all times.