Übersetzung für "Ammoniakschlupf" in Englisch

This would lead to ammonia leakage, which must absolutely be avoided when a CDC is involved.

The extent of nitrogen oxide removal can therefore be clearly improved and the escape of ammonia even further reduced.

In particular, ammonia slip downstream of the catalytic converter is therefore preferably measured as the measurement signal.

Provided at the outlet side of each catalytic converter part is a sensor provided which measures the ammonia slip of the respective catalytic converter part.

In addition, slip-regulated reducing agent metering proves to be difficult if the ammonia slip is to be completely avoided.

If a predefined ammonia slip is exceeded downstream from the first upstream SCR catalytic converter, the reducing agent feed is discontinued.

Measurements confirm that the official emission limit values for nitrogen oxide and for the ammonia slip are clearly under-run.

In a highly efficient SCR system there is a risk of ammonia slip behind the SCR catalyst.

The emission limit set for NH3 in Regulation (EC) No 595/2009 of the European Parliament and of the Council5 is a requirement designed to limit the slip of ammonia from NOx after treatment technologies which use a urea reagent for the reduction of NOx.

In both cases, ammonia that is not used during the reduction reaction of the nitrogen monoxide can be carried off in the exhaust gases as a so-called ammonia blow-by or slip.

Thus, for the metered addition of the reducing agent in the CDC system, there is thus far no suitable control capability, and as a result if there are defects in the catalyst or at the metering valve, annoyance can be created by excessive leakage of ammonia.

An on-board diagnosis system in a vehicle can call up these performance graph data and from them derive a metering of the ammonia, for instance in the form of an aqueous urea solution, so that high degrees of settling for the nitrogen oxides contained in the exhaust gas 36 are attainable, with comparatively negligible ammonia leakage.

However, it has been definitively found that in the metered addition of the reducing agent in an SCR or CDC system, there is thus far no suitable control capability, and as a result if there is a defect, for instance in the catalytic converter or at the metering valve, annoyance can be created by excessive leakage of ammonia.

The operating state represented by course b is accordingly distinguished by a maximum possible degree of conversion for nitrogen oxides, with negligible ammonia leakage, and is therefore either established or sought by means of the control unit 38 when the Diesel engine 4 is in operation.

As a result of the downstream location of the oxidation catalyst, a further advantage of the invention resides in the fact that an ammonia leak can be completely avoided in the overall installation, since the small quantity of unused ammonia from the denitrification step is completely oxidized at the oxidation catalyst.

In the case of each denitrification installation operated with ammonia moreover, the problem occurs, that this reduction agent is not completely converted and a small quantity of it, designated as "ammonia leakage", is present in the flue gas after it passes through the denitrification installation.

These are primarily variables relating to the nitrogen oxide content of the exhaust gas flowing out of the catalytic converter, the ammonia slip S NH3 and the exhaust gas temperature which has if appropriate varied as a result of the reaction heat or as a result of heat losses.

It is provided that the calculations are carried out separately for the catalytic converter parts 3, 4, with the desorption rate or the ammonia slip S NH3 of the first catalytic converter part constituting the ammonia supply rate Z of the second catalytic converter part 4 .

The values for the conversion with nitrogen oxides, the direct conversion with oxygen and the desorption rate given by the ammonia slip S NH3 are passed together with the ammonia supply rate Z to a summing junction 63 which sums the relevant variables according to their signs.

With a normal operation of the diesel engine, 1, the SCR catalyst is supplied with ammonia or urea solution with recourse to a model-based control or regulation in such a manner that a maximum conversion with a simultaneous maintaining of a presettable limit value for an ammonia slip results.

The second SCR stage serves to complete the conversion of the nitrogen oxides. The second stage is operated with a sub-stoichiometric amount of ammonia in relation to the nitrogen oxide concentration in the exhaust gas in order to prevent the risk of ammonia slipping through the entire exhaust system.

In general, however, it is desirable to keep the emissions of pollutants in the exhaust gas of internal combustion engines, and thus also ammonia slip, as low as possible.

It is therefore a feature of the present invention to provide a process and a plant suitable therefor which ensures, by means of a combination of a secondary catalyst in the process gas stream with a deNO x stage containing an iron-loaded zeolite catalyst in the tailgas stream, both a high degree of removal of NO x and also of N 2 O without ammonia breakthrough in the resulting offgas stream occurring.

Such an arrangement allows the reducing agent feed to be optimally adjusted over the entire available SCR catalytically active zone; the maximum allowable ammonia slip over the SCR catalytically active zones is to be adapted to the efficiency of the ammonia oxidation catalytic converter.

If the setpoint value of the controller were set equal to zero, this would be equivalent to the ammonia slip between the first and second SCR unit.