HJS have been eliminating soot from diesel exhaust emissions since the early 1990’s and have developed a diesel particle filter manufactured from Sintered Metal (Sintered Metal Filter or SMF®) for exactly this purpose. For its innovative and enterprising approach toward environmental protection, HJS have been proudly awarded the German environmental prize for the SMF product.
Further to this, and to address the issue of gaseous pollutants, HJS teamed up with Daimler and Johnson Matthey to combine a Diesel Particulate Filter (DPF) system with a NOx reduction system. Known and patented as Selective Catalytic Reduction Technology (SCRT®) this modular system can almost completely remove Nitrogen Dioxides from the diesel exhaust and be applied to a wide range of diesel powered applications.
For the decomposition and regeneration of the soot collected within the filter unit, passive filter regeneration is used. With passive filter regeneration, a catalyst is installed upstream of the DPF which converts the Nitric Oxide (NO) in the exhaust gas into Nitrogen Dioxide (NO2). The particulate filter then utilises the NO2 for the combustion or oxidisation of the soot.
The next section of an SCRT® system typically features an SCR catalyst and an Ammonia injection system for the reduction of Nitrogen Dioxides. Also known as Adblue, the Ammonia is injected into the exhaust stream after the DPF and before the SCR catalyst. In the heat of the exhaust gases the Adblue is thermally converted into Ammonia (NH3) and this Ammonia then acts by reducing the Nitrogen Oxides into Nitrogen (N2) and water (H2O) as it passes over the SCR catalyst.
The SCRT® system therefore reduces environmental pollution and the health endangering Nitrogen Dioxide emissions of a diesel engine by up to 99 percent. In combination with a DPF, the SCRT® system can reduce almost all pollutants in diesel exhaust gases.
Area of application
SCRT® systems are used both in the private car and commercial vehicle sectors and the technology is widely used to reach Euro VI or EPA 2010 emissions standards. Many Non Road diesel engines also use this type of technology to reach Stage V which will be introduced in 2019 and affects the construction, marine, agricultural and forestry industries. Further plans are also underway which will mean that the rail industry will also be required to comply with stringent emission levels. The HJS SCRT® system is available for a wide range of applications for both the Original Equipment and retrofit markets.