BlueTec

SCRT (Selective Catalytic Reduction Technology ) is a technology for minimizing nitrogen oxides (NOx), particulate matter (PM ), hydrocarbons ( HC) and carbon monoxide (CO) in the exhaust gases of diesel engines. The SCRT system is a combination of a diesel particulate filter ( wall-flow filter) or a by-pass filter (low flow deep-bed filters ) (eg, a PM- Kat ) and a SCR unit (Selective Catalytic Reduction) technology for diesel engines. The SCRT system reduces particulate matter and nitrogen oxide emissions by up to 90 percent. Specifically, the fine particle mass is at least 30% (typically 50 %), reduced the number of fine particles more than 80% and NOx by 90 %. SCRT is now a registered trademark of HJS in Menden.

The company Emitec calls this combination of diesel particulate filters and SCR unit (Selective Catalytic Reduction) SCR i - system, the " i" stands for integrated.

Operation

The SCRT system uses the first step, the CRT effect (continuously regenerating trap) - registered trademark of Johnson Matthey Emission Control Technologies - to reduce the accumulated soot in the diesel particulate filter. This converts an upstream oxidation catalyst or the catalytically active coating, the filter in the exhaust gases existing nitrogen monoxide (NO ) into nitrogen dioxide (NO2) to. This nitrogen dioxide enables a temperature range of 350 to 500 degrees Celsius and then a continuous combustion of the soot accumulated in the particulate filter ( soot oxidation ).

In the second step reduces the SCR ( Selective Catalytic Reduction), nitrogen oxides (NOx). The exhaust gases continuously, an aqueous urea solution ( AdBlue brand name ) is behind the diesel particulate filter to mixed, from which arise by hydrolysis of water and ammonia. The resulting ammonia reduces nitrogen oxides in the exhaust gas to normal nitrogen (N2).

SCRi the system, the urea solution (e.g. AdBlue) already sprayed on the rear end of the oxidation catalyst, the so-called Hydrolyseteil. The nozzle is installed nearly flush with the catalyst coat. The urea is injected ie before the bypass filter (low flow deep-bed filters). Due to the turbulence generating metal sheet profiles (keyword: Mixer film ) of the particulate filter, the urea solution is thoroughly mixed with the exhaust gas. In addition, the particulate filter has a so-called hydrolysis coating, which supports the generation of ammonia. Since ammonia production requires a short period of time, the actual reduction of NOx does not start until after a delay of the particulate filter.

Scope

SCRT systems are both in cars, trucks and commercial vehicles, but also in non-road diesel engines used, such as in construction equipment, agricultural and forestry machinery, ships and trains. The SCRT technology is suitable for use as original equipment and for retrofitting.

Background

In Germany, Europe and internationally various measures to reduce emissions of pollutants at the source ( emissions) and to regulate the concentrations in ambient air are introduced. For example, does the emission legislation in the EU and the USA for passenger cars, commercial vehicles and mobile machines in the future the use of exhaust aftertreatment systems before. These are intended to reduce pollutants such as particulates and nitrogen oxides. The Air Quality Directive applicable throughout Europe, provides for a reduction of the pollutant concentration in the ambient air ( ambient air ). It defines, among other limits to reducing air pollution and it looks from 1 January 2010 a significant reduction of nitrogen oxide emissions (NOx ) ago. Nitrogen oxides are emitted primarily by the burning of fossil fuels and fuels as well as waste. The main sources are the transport ( road and air transport, maritime transport ), the so- called non -road sector (construction machinery, agricultural and forestry machinery ) as well as the trade and industry. Especially in the big cities and along busy streets applicable immission limit values ​​for nitrogen dioxide ( NO2) are regularly exceeded. This is due to, among other things, the growing number of diesel-powered vehicles. From 2010, the EU Air Quality Directive therefore provides more stringent limits for NO2 ago: From then annual average of 40 micrograms applies / m³, the 1 -hour maximum value is 200 ug / m³ not to be exceeded in more than 18 times.