Durch den Einsatz der SCR-Abgasnachbehandlungstechnologie für Dieselmotoren können die zukünftigen Europäischen Emissionsgrenzwerte eingehalten werden. Der Einsatz der SCR-Technologie zur Reduzierung der NO(x)-Emissionen bietet die Möglichkeit, den Motor auf einen sehr günstigen Wirkungsgrad zu optimieren, welches einen geringen Kraftstoffverbrauch und niedrige Partikelemissionen zur Folge hat. war es wichtig, sich gemeinsam für ein Produkt für Europa zu entscheiden. Im September 2001 entschieden die Vorstände der Europäischen Nutzfahrzeughersteller, eine wässrige Harnstofflösung für die SCR-Technologie in Europa einzusetzen. Der Europäische Handelsname der wässrigen Harnstofflösung für den Automobileinsatz ist 'AdBlue'. Eine modulare Bauweise des hier vorgestellten druckluftunterstützten DeNOxierungssystems ermöglicht eine Optimierung der Einzelkomponenten hinsichtlich ihrer günstigsten individuellen Position am Rahmen oder Motor unter gleichzeitiger Berücksichtigung eines hohen Maßes an Gleichteilen. Der erforderlichen Wirtschaftlichkeit der Produktionsbedingungen sowie der Integration des Abgasreinigungssystems in das Fahrzeug wird dadurch Rechnung getragen. Es besteht aus den Komponenten Einspritzdüse, Dosiereinheit, Druckluftsteuerung, AdBlue-Versorgungseinheit. Der Aufbau der Infrastruktur von AdBlue ist derzeit in Europa durch Mineralölfirmen, Chemiedistributionsunternehmen und Harnstoffproduzenten in vollem Gange.
The industrial nations have all introduced laws and guidelines to ensure the modification of exhaust emissions caused by vehicles. The emission directives Euro 4 and Euro 5 passed by the European Parliament in 1999 have succeeded, with Euro 4, in bringing about a new milestone in the development of utility vehicles: exhaust gas treatment. The SCR system, the individual components of which are described here in closer detail, was launched in February 2005, achieving advance compliance with Euro 4 and Euro 5. The diesel engine is adjusted to maximum efficiency and the particle emissions conform to limit values. Implementing SCR technology achieves the limit value classes for nitrogen oxide emissions prescribed in Euro 4 and Euro 5. This method of nitrogen oxide control calls for a reducing agent. In this case, AdBlueTM, an aqueous urea solution, is injected into the exhaust gas flow and the reducing agent, ammonia, for the SCR reactions is released at the catalytic converter. Thanks to the modular structure of the compressed air-based deNO(x) system presented here it is possible to optimise the individual components as far as the most practical specific position on the frame or motor is concerned. At the same time, uniform parts can be implemented to a great extent. The necessary economic efficiency of manufacturing as well as the integration of the exhaust gas cleaning system in the vehicle are consequently taken into account. Due to its specific properties, the reducing agent AdBlueTM places extremely high demands on the development of the deNO(x) systems in respect of frost-resistance, clogging at high temperatures as a result of crystallisation, and the material compatibility of the medium-conducting components. Great precision when dosing the reducing agent is of prime importance to the reduction potential of nitrogen oxides, and also to the prevention of inadmissible secondary emissions. Intensive, far-reaching component tests and driving performance trials are necessary in order to reliably present the entire exhaust gas cleaning system for everyday use in utility vehicles that run up annual mileages of 250000 km and more. These include component testing under extreme climatic conditions and combined mechanical and thermal continuous stressing in accelerated tests, as well as vehicle trials under extreme real and permanent conditions. The implementation of SCR technology in series production represents a milestone because it has also created the basis for future exhaust gas cleaning technology. In combination with other technologies such as catalytic oxidation and particle filtration, this means that even more stringent emission requirements can be fulfilled.
Selektive Katalytische Reduktion (SCR) im Serieneinsatz für Nutzfahrzeuge: Ein Meilenstein in der Abgasreinigungstechnologie
Selective Catalytic Reduction (SCR) as original equipment on commercial vehicles: A milestone in exhaust aftertreatment technology
2005
13 Seiten, 9 Bilder
Conference paper
German
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