Retrofit Diesel Particulate Filters with EHC
Our diesel particulate filters can be retrofitted to diesel engines, in order to remove diesel particulate matter (PM or soot). Based on engine technology and application specifications, different filter technologies may be used to reduce particle emissions depending on the circumstances. Keep reading to learn more.
If you have questions about retrofitting our diesel particulate filters, we would love to hear from you.
Wall-Flow Filters – a type of DPF
In wall flow filters, particulate matter is removed from the exhaust by physical filtration using a honeycomb structure, similar to emission catalyst substrates but with the channels blocked at alternate ends. This forces the exhaust gas to flow through the walls between the channels. The particulate matter is deposited as a “soot cake” on the walls. These filters are made of ceramic honeycomb materials (cordierite, silicon carbide or aluminium titanate).
Ceramic wall-flow filters will almost completely remove the carbon particulates, including fine particulates with a diameter of less than 100 nanometers (nm) with an efficiency of >95% in mass and >99% in number of particles over a wide range of engine operating conditions. Since the continuous flow of soot into the filter would eventually block it, it is necessary to “regenerate” the filtration properties of the filter by burning the collected soot on a regular basis. The burn off from the soot particulates will form mostly water, and small quantities of CO2 (less than 0.05% of the CO2 emitted by the engine).
The most successful methods for achieving regeneration in retrofit applications include:
- Incorporating an oxidation catalyst upstream of the filter that, as well as operating as a conventional oxidation catalyst, also increases the ratio of NO2 to NO in the exhausts. Trapped particulates will then burn off at lower exhaust temperatures, thanks to the powerful oxidative properties of NO2 and oxygen.
- Incorporating a catalytic coating on the filter. This will lower the temperature threshold for the regeneration to match normal exhaust temperatures.
- Adding catalysts such as iron or ceria additive compounds to the fuel tank through an on-board dosing system. When the catalyst is collected on the filter mixed with the particulate, it will help the particulate burn at lower exhaust temperatures (around 300-330°C compared to 650°C) and increase the combustion kinetic (typically 2-3 minutes) while the solid residues of the catalyst are retained on the filter as ashes. To maintain the long-term integrity of the filter, it is critical to take control of the combustion process. Its performances in terms of temperature and kinetics makes FBC technology particularly suitable for urban and stop-and-go driving with low fuel penalty.
- External heating of the filter with electrical heaters, either on or off the vehicle or machinery. This method applies only to industrial applications and is usually only used when the engine is shut off.
- Fuel injector in the exhaust line upstream of the DPF.
Are you interested in retrofitting vehicles with DPFs? Please get in touch with us to find the right filter solution.