Using urea to reduce Nox emissions

Automotive Industries, Spring, 2008 by Nick Palmen

Selective Catalytic Reduction (SCR) is helping motor companies to go greener by converting the nitric oxides of the exhaust gases into water and atmospheric nitrogen. In order to induce the reaction, which takes place in the SCR converter, an ammonium fluid is injected into the exhaust system. This ammonium fluid--also called urea fluid--is already available on the market.

One of the pioneers of this technology is the Norma Group, which has subsidiaries in Germany, England, France, Spain, the USA, Australia, Poland and Singapore. Automotive Industries asked Thomas Kraus, Automotive Sales Director of the Norma Group, when the new technology would be introduced to the market.

Kraus: Urea-proof exhaust system couplers are already in series production for trucks for the European market. Series production for injector fixation clamps and urea fluid lines for the US market began production in June this year.

AI: Which carmakers have already implemented the technology?

Kraus: Daimler was the first truck manufacturer to implement our urea tight exhaust system couplers, profile clamps and quick connectors into it's trucks. Daimler was also the first manufacturer in the passenger car market to announce the use of SCR technology including urea injection.

[ILLUSTRATION OMITTED]

Currently we are also developing new urea systems with several other car manufacturers. As the cars are not launched to the market, I can not tell you the details.

AI: What results do you expect from the SCR portfolio?

Kraus: Due to our high level of competency in this area, a large number of OEMs and 1st Tier suppliers have selected Norma as their global development partner for SCR technology. The big advantage for our customers is that Norma has a large variety of products, which can be adapted to provide the complete SCR system in any vehicle.

AI: What are the biggest challenges in designing an entire urea-system from conception to serial application?

Kraus: One of the challenges we faced was the fact that the Ad Blue (urea) liquid freezes easily at -11[degrees]C. Norma solved this problem by developing Norma Fluid pipes and Norma Quick connectors with integrated heating wires. By doing this, we created a brand new fluid transport system which unfreezes the urea fluid directly after the engine starts and keeps it liquid while the vehicle is driving.

Norma engineers also developed a new Quick Connector which can be welded directly to the nylon pipe even though the inside diameter of the pipe is only two millimeters.

AI: What are the advantages of NormaFLEXUrea systems to the customer?

[ILLUSTRATION OMITTED]

Kraus: The pipes, with a length of up to six meters, can be thermoformed like a standard fuel pipe. The tight bending radius and the small external diameter provide more available space. Equipped with different clips or retaining elements, the urea conveyer and filler and ventilation pipes can be easily attached to the vehicle. The electrical wiring and connections can also be adapted to the individual requirements of the vehicle.